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Sample records for 13co c18o hcn

  1. Influence of Interstellar FUV Radiation on the Abundance Ratio of 13CO to C18O in L 1551

    NASA Astrophysics Data System (ADS)

    Lin, Sheng-Jun; Shimajiri, Yoshito; Hara, Chihomi; Lai, Shih-Ping; Nakamura, Fumitaka; Sugitani, Koji; Kawabe, Ryohei; Kitamura, Yoshimi; Yoshida, Atsushi; Tatei, Hidefumi; Akashi, Toshiya; Tsukagushi, Takashi

    2015-08-01

    To investigate the relationship between the far-ultraviolet (FUV) radiation and the abundance ratios between 13CO and C18O, we observed L 1551 in 12CO (J=1-0), 13CO (J=1-0) and C18O (J=1-0) using the Nobeyama Radio Observatory 45 m telescope with an angular resolution of ~22" (corresponding to 0.017 pc at a distance of 160 pc). L 1551 is chosen because it is relatively isolated in Taurus-Auriga complex, providing an ideal environment for studying the variation of abundance ratio due to the penetration of the FUV photons. L 1551 is a young star-forming region containing at least 6 young protostars between Class I and Class III stages and a quiescent elongated starless core. The distribution of 12CO emission shows the outflows coming from 2 youngest protostars IRS5 and NE. The 13CO and C18O are detected throughout the whole region with enhancement around the outflows and depletion in the outflow cavities. To avoid the influence of outflows, we exclude the outflow regions for X(13CO)/X(C18O) abundance ratio calculation. X(13CO)/X(C18O) is found in the range of 3.2 -- 36.2 with a mean value of 7.6. Comparing to the extinction map derived from Herschel observations, we found that the abundance ratio reaches its maximum at low AV and decreases to typical solar system value of 5.5 within the starless core. The high X(13CO)/X(C18O) value at the low AV value in L 1551 is most likely due to the selective FUV photodissociation of C18O. This is in contrast with Orion-A region where its internal OB stars keep the abundance ratio at a high level greater than ~10.

  2. 12CO, 13CO and C18O observations along the major axes of nearby bright infrared galaxies

    NASA Astrophysics Data System (ADS)

    Tan, Qing-Hua; Gao, Yu; Zhang, Zhi-Yu; Xia, Xiao-Yang

    2011-07-01

    We present simultaneous observations of 12CO, 13CO and C18O J = 1-0 emission in 11 nearby (cz < 1000km s-1) bright infrared galaxies. Both 12CO and 13CO are detected in the centers of all the galaxies, except for 13CO in NGC 3031. We have also detected C18O, CS J = 2-1 and HCO+ J = 1-0 emission in the nuclear regions of M82 and M51. These are the first systematical extragalactic detections of 12CO and its isotopes from the PMO 14m telescope. We have conducted half-beam-spaced mapping of M82 over an area of 4' × 2.5' and major axis mapping of NGC 3627, NGC 3628, NGC 4631 and M51. The radial distributions of 12CO and 13 CO in NGC 3627, NGC 3628 and M51 can be well fitted by an exponential profile. The 12CO/13CO intensity ratio, Script R, decreases monotonically with the galactocentric radius in all mapped sources. The average Script R in the center and disk of the galaxies are 9.9±3.0 and 5.6±1.9, respectively, much lower than the peculiar Script R(~24) found in the center of M82. The intensity ratios of 13CO/C18O, 13CO/HCO+ and 13CO/CS (either our or literature data) show little variation with galactocentric radius, in sharp contrast with the greatly varied Script R. This supports the notion that the observed gradient in Script R could be the result of the variations of the physical conditions across the disks. The H2 column density derived from C18O shows that the Galactic standard conversion factor (X-factor) overestimates the amount of the molecular gas in M82 by a factor of ~2.5. These observations suggest that the X-factor in active star-forming regions (i.e., nuclear regions) should be lower than that in normal star-forming disks and the gradient in Script R can be used to trace the variations of the X-factor.

  3. Dense Cores of Dark Clouds. XII. 13CO and C18O in Lupus, Corona Australis, Vela, and Scorpius

    NASA Astrophysics Data System (ADS)

    Vilas-Boas, J. W. S.; Myers, P. C.; Fuller, G. A.

    2000-04-01

    More than 110 dense condensations of the dark clouds in Lupus, Corona Australis, Norma, Vela, and Scorpius were observed in the 13CO and C18O (J=1-0) transitions. The condensations of dark clouds with high star formation activity like the Ophiuchus, Taurus, and Cepheus have average C18O and H2 column densities of 1.8x1015 and 1.1x1022 cm-2. If we take the average size of the condensations to be 0.2 pc, a condensation must have average H2 volumetric densities >=2x104 cm-3 in order to be a good candidate to form stars. The four Lupus filaments have similar radial velocities and velocity dispersions, suggesting that they originated from the same parental cloud. Among these filaments, Lupus 1 is unique in having recent star formation activity, despite the high number of T Tauri stars observed toward the others. Lupus 1 also shows a complex velocity gradient along its main axis. The distribution of radial velocities of the condensations observed toward Scorpius are in good agreement with the hypothesis that they are in a region with expansion velocity smaller than or equal to 18 km s-1. The Corona Australis cloud has velocity gradients ranging from -0.5 km s-1 pc-1 at one extreme to 0.1 km s-1 pc-1 at the other.

  4. CHIMPS: the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey

    NASA Astrophysics Data System (ADS)

    Rigby, A. J.; Moore, T. J. T.; Plume, R.; Eden, D. J.; Urquhart, J. S.; Thompson, M. A.; Mottram, J. C.; Brunt, C. M.; Butner, H. M.; Dempsey, J. T.; Gibson, S. J.; Hatchell, J.; Jenness, T.; Kuno, N.; Longmore, S. N.; Morgan, L. K.; Polychroni, D.; Thomas, H.; White, G. J.; Zhu, M.

    2016-03-01

    We present the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| ≤ 0.5° and 28° ≲ l ≲ 46°, with an angular resolution of 15 arcsec in 0.5 km s-1 velocity channels. The spectra have a median rms of ˜0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of NH2 ˜ 3 × 1020 cm-2 and NH2 ˜ 4 × 1021 cm-2 for 13CO and C18O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J = 3 → 2 transition of CO is ≳104 cm-3 at temperatures of ≤20 K, and so the higher density gas associated with star formation is well traced. These data complement other existing Galactic plane surveys, especially the JCMT Galactic Plane Survey which has similar spatial resolution and column density sensitivity, and the Herschel infrared Galactic Plane Survey. In this paper, we discuss the observations, data reduction and characteristics of the survey, presenting integrated-emission maps for the region covered. Position-velocity diagrams allow comparison with Galactic structure models of the Milky Way, and while we find good agreement with a particular four-arm model, there are some significant deviations.

  5. The JCMT Legacy Survey of the Gould Belt: mapping 13CO and C18O in Orion A

    NASA Astrophysics Data System (ADS)

    Buckle, J. V.; Davis, C. J.; Francesco, J. Di; Graves, S. F.; Nutter, D.; Richer, J. S.; Roberts, J. F.; Ward-Thompson, D.; White, G. J.; Brunt, C.; Butner, H. M.; Cavanagh, B.; Chrysostomou, A.; Curtis, E. I.; Duarte-Cabral, A.; Etxaluze, M.; Fich, M.; Friberg, P.; Friesen, R.; Fuller, G. A.; Greaves, J. S.; Hatchell, J.; Hogerheijde, M. R.; Johnstone, D.; Matthews, B.; Matthews, H.; Rawlings, J. M. C.; Sadavoy, S.; Simpson, R. J.; Tothill, N. F. H.; Tsamis, Y. G.; Viti, S.; Wouterloot, J. G. A.; Yates, J.

    2012-05-01

    The Gould Belt Legacy Survey will map star-forming regions within 500 pc, using Heterodyne Array Receiver Programme (HARP), Submillimetre Common-User Bolometer Array 2 (SCUBA-2) and Polarimeter 2 (POL-2) on the James Clerk Maxwell Telescope (JCMT). This paper describes HARP observations of the J= 3 → 2 transitions of 13CO and C18O towards Orion A. The 15 arcsec resolution observations cover 5 pc of the Orion filament, including OMC 1 (including BN-KL and Orion bar), OMC 2/3 and OMC 4, and allow a comparative study of the molecular gas properties throughout the star-forming cloud. The filament shows a velocity gradient of ˜1 km s-1 pc-1 between OMC 1, 2 and 3, and high-velocity emission is detected in both isotopologues. The Orion Nebula and Bar have the largest masses and linewidths, and dominate the mass and energetics of the high-velocity material. Compact, spatially resolved emission from CH3CN, 13CH3OH, SO, HCOOCH3, CH3CHO and CH3OCHO is detected towards the Orion Hot Core. The cloud is warm, with a median excitation temperature of ˜24 K; the Orion Bar has the highest excitation temperature gas, at >80 K. The C18O excitation temperature correlates well with the dust temperature (to within 40 per cent). The C18O emission is optically thin, and the 13CO emission is marginally optically thick; despite its high mass, OMC 1 shows the lowest opacities. A virial analysis indicates that Orion A is too massive for thermal or turbulent support, but is consistent with a model of a filamentary cloud that is threaded by helical magnetic fields. The variation of physical conditions across the cloud is reflected in the physical characteristics of the dust cores. We find similar core properties between starless and protostellar cores, but variations in core properties with position in the filament. The OMC 1 cores have the highest velocity dispersions and masses, followed by OMC 2/3 and OMC 4. The differing fragmentation of these cores may explain why OMC 1 has formed

  6. Dense cores in dark clouds. 9: Observations of (13)CO and C(18)O in Vela, Chamaeleon, Musca, and the Coalsack

    NASA Astrophysics Data System (ADS)

    Vilas-Boas, J. W. S.; Myers, P. C.; Fuller, G. A.

    1994-09-01

    One hundred one condensations with average optical size less than 7 min and visual extinction greater than 2.5 mag have been selected from European Southern Observatory (ESO) J plates, extinction maps, and catalogs of southern hemisphere dark clouds for observation in the (13)CO and C(18)O J = 1 goes to 0 transitions. These regions are condensations in the dark molecular clouds Musca, Coalsack, Chamaeleon II, Chamaeleon III, and cometary globules in Vela and Gum nebula. A search for IRAS point sorces having colors of young stellar objects shows that these condensations have at most seven associated young stellar objects-far fewer than in Taurus and Ophiuchus. These 101 condensations generally have lower (13)CO and C(18)O line intensity, C(18)O optical depth, and (13)CO line width than do 90 condensations in Taurus, Ophiuchus, and Cepheus. Similarly, 47 of these southern condensations having star-count estimates of visual extinction generally have less extinction than do the 19 condensations in Taurus having extinction estimated by the same method. The C(18)O to (13)CO line-width ratio for the cometary globules in the Vela ragion is greater than for the other clouds, indicating that the (13)CO line width observed toward dark cloud condensations is related to the more extended and less dense intercondensation gas. Radial velocities suggest that the system of Vela globules has velocity dispersion 4.7 km/s, which is at least 2 times greater than the dispersion determined from formalhyde observations. The Musca filament has velocities which are slightly higher-by approximately 0.5 km/s-in the center than at the ends of the filament. Chamaeleon III has a 0.2 km/s velocity gradient and Chamaeleon II has no indication of velocity gradients. The Chamaeleon clouds and the Musca filament appear close to virial equilibrium.

  7. Analysis Of The California Molecular Cloud Through CS J(2-1), HCN J(1-0), And C18O J(2-1)molecular Tracers

    NASA Astrophysics Data System (ADS)

    Jasso, Steven; Shirley, Y.; Bieging, J.; Rudolph, A.; Lada, C.; Forbrich, J.; Roman, C.

    2012-01-01

    The California Molecular Cloud (CMC) is a nearby (D 450 pc) complex cloud with a total mass similar to the Orion Molecular Cloud but with only one-tenth the star formation rate. Studies of the CMC therefore provide a unique opportunity to probe the conditions of dense molecular gas in a quiescent star forming environment. We provide CS J(2-1) and HCN J(1-0) spectra taken with the Arizona Radio Observatory 12m telescope at Kitt Peak, as well as C18O J(2-1) spectra from the Heinrich Hertz Submillimeter Telescope on Mt. Graham, AZ, for 37 high opacity cores chosen from a near-infrared extinction map of the CMC. Analysis of the line properties were made through Gaussian fits to the line profiles. We present a statistical comparison of the line properties for sources in the CMC with a sample of 36 cores in Orion A from Tatematsu et al. and a larger sample of 150 intermediate and high-mass cores from Plume et al. We acknowledge the NSF for funding under Award No. AST-0847170, a PAARE Grant for the Calfornia-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE).

  8. A 1.85-m mm-submm Telescope for Large-Scale Molecular Gas Surveys in 12CO, 13CO, and C18O (J = 2-1)

    NASA Astrophysics Data System (ADS)

    Onishi, Toshikazu; Nishimura, Atsushi; Ota, Yuya; Hashizume, Akio; Kojima, Yoshiharu; Minami, Akihito; Tokuda, Kazuki; Touga, Shiori; Abe, Yasuhiro; Kaiden, Masahiro; Kimura, Kimihiro; Muraoka, Kazuyuki; Maezawa, Hiroyuki; Ogawa, Hideo; Dobashi, Kazuhito; Shimoikura, Tomomi; Yonekura, Yoshinori; Asayama, Shin'ichiro; Handa, Toshihiro; Nakajima, Taku; Noguchi, Takashi; Kuno, Nario

    2013-08-01

    We have developed a new mm-submm telescope with a diameter of 1.85-m installed at the Nobeyama Radio Observatory. The scientific goal is to precisely reveal the physical properties of molecular clouds in the Milky Way Galaxy by obtaining a large-scale distribution of molecular gas, which can also be compared with large-scale observations at various wavelengths. The target frequency is ˜ 230 GHz; simultaneous observations at the molecular rotational lines of J = 2-1 of three carbon monoxide isotopes (12CO, 13CO, C18 O) are achieved with a beam size (HPBW) of 2.7'. In order to accomplish the simultaneous observations, we have developed waveguide-type sideband-separating SIS mixers to obtain spectra separately in the upper and lower side bands. A Fourier digital spectrometer with a 1 GHz bandwidth having 16384 channels is installed, and the bandwidth of the spectrometer is divided into three parts, corresponding to each of the three spectra; the IF system has been designed so as to inject these three lines into the spectrometer. A flexible observation system was created mainly in Python on Linux PCs, enabling effective OTF (On-The-Fly) scans for large-area mapping. The telescope is enclosed in a radome with a membrane covered to prevent any harmful effects of sunlight, strong wind, and precipitation in order to minimize errors in the telescope pointing, and to stabilize the receiver and the IF devices. From 2011 November, we started science operation, resulting in a large-scale survey of the Orion A/B clouds, Cygnus OB7, Galactic Plane, Taurus, and so on. We also updated the receiver system for dual-polarization observations.

  9. Physical properties of the OMC-2 and OMC-3 cores from CS and C(18)O observations

    NASA Technical Reports Server (NTRS)

    Castets, A.; Langer, W. D.

    1995-01-01

    We have investigated the properties of the OMC-2 and OMC-3 cores in the Orion giant molecular cloud using high spatial spectral resolution observations of several transitions of the (13)CO, C(18)O, C(S-32) and C(S-34) molecules taken with the SEST telescope. The OMC-2 core consists of one clump (22 solar mass) with a radius of 0.11 pc surrounded by a cluster of 11 discrete infrared sources. The H2 column density and volume density in the center of this clump are 2 x 10(exp 22)/sq cm and 9 x 10(exp 5)/cu cm respectively. From a comparison between physical parameters derived from C(18)O and C(S-32) observations we conclude that the molecular envelope around the core has been completely removed by these sources and that only the very dense gas is left. OMC-3 shows a more complex elongated structure in C(18)O and CS than OMC-2. The C(S-32) and C(S-34) maps show that the denser region can be separated into at least sub-cores of roughly equal sizes (radius approximately equals 0.13 pc), with n(H2) = 6 x 10(exp 5)/cu cm, and a mass of 10 solar mass (from C(S-32)). The very different masses obtained for the central core from C(18)O and C(S-32) (55 and 12 solar mass respectively) indicate that a massive envelope is still present around the very dense sub-cores. We report the first detection of several molecular outflows in OMC-3. The presence of an IRAS source and the first detection of these outflows confirm that star formation is going on in OMC-3. Based on the different physical properties of these regions compared with OMC-1, OMC-2 appears to be in an intermediate evolutionary stage between OMC-1 and OMC-3.

  10. VizieR Online Data Catalog: HCO+ and HCN obs. toward Planck Galactic Cold Clumps (Yuan+, 2016)

    NASA Astrophysics Data System (ADS)

    Yuan, J.; Wu, Y.; Liu, T.; Zhang, T.; Li, J. Z.; Liu, H.-L.; Meng, F.; Chen, P.; Hu, R.; Wang, K.

    2016-05-01

    More than 600 Planck cold clumps have been mapped in the J=1-0 transitions of 12CO, 13CO, and C18O. A 22'x22' region for each clump was mapped with a spatial resolution of about 52". Details about the mapping observations are provided by Liu et al. (2012, J/ApJS/202/4) and Meng et al. (2013, J/ApJS/209/37). Single-pointing observations of the CO-selected cores in HCO+ J=1-0 (89.189GHz) and HCN J=1-0 (88.632GHz) were carried out using the 13.7m telescope of the Purple Mountain Observatory (PMO) with the position-switch mode from 2013 June to July and from 2014 May to June. (2 data files).

  11. Large and unexpected enrichment in stratospheric 16O13C18O and its meridional variation

    PubMed Central

    Yeung, Laurence Y.; Affek, Hagit P.; Hoag, Katherine J.; Guo, Weifu; Wiegel, Aaron A.; Atlas, Elliot L.; Schauffler, Sue M.; Okumura, Mitchio; Boering, Kristie A.; Eiler, John M.

    2009-01-01

    The stratospheric CO2 oxygen isotope budget is thought to be governed primarily by the O(1D)+CO2 isotope exchange reaction. However, there is increasing evidence that other important physical processes may be occurring that standard isotopic tools have been unable to identify. Measuring the distribution of the exceedingly rare CO2 isotopologue 16O13C18O, in concert with 18O and 17O abundances, provides sensitivities to these additional processes and, thus, is a valuable test of current models. We identify a large and unexpected meridional variation in stratospheric 16O13C18O, observed as proportions in the polar vortex that are higher than in any naturally derived CO2 sample to date. We show, through photochemical experiments, that lower 16O13C18O proportions observed in the midlatitudes are determined primarily by the O(1D)+CO2 isotope exchange reaction, which promotes a stochastic isotopologue distribution. In contrast, higher 16O13C18O proportions in the polar vortex show correlations with long-lived stratospheric tracer and bulk isotope abundances opposite to those observed at midlatitudes and, thus, opposite to those easily explained by O(1D)+CO2. We believe the most plausible explanation for this meridional variation is either an unrecognized isotopic fractionation associated with the mesospheric photochemistry of CO2 or temperature-dependent isotopic exchange on polar stratospheric clouds. Unraveling the ultimate source of stratospheric 16O13C18O enrichments may impose additional isotopic constraints on biosphere–atmosphere carbon exchange, biosphere productivity, and their respective responses to climate change. PMID:19564595

  12. - and Air-Broadening of 12C16O, 13C16O and 12C18O at 2.3 μm

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Smith, Mary Ann H.; Mantz, Arlan W.; Sung, Keeyoon; Brown, Linda R.

    2011-06-01

    High resolution (0.005 Cm-1) absorption spectra of CO and two of its isotopologues (13CO and C18O) were recorded between 3550 and 5250 Cm-1 using the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Jet Propulsion Laboratory (JPL) and a specially designed and built coolable 20.38 cm long absorption cell placed within the sample compartment of the FTS. More than 50 spectra of both pure and air-broadened samples of CO, 13CO and C18O were recorded at various temperatures from 150 K to 298 K, with maximum total pressures up to ˜700 Torr. A multispectrum nonlinear least squares spectrum fitting technique was used to determine the spectral line shape parameters including speed dependence, Lorentz halfwidth coefficients, pressure-induced shift coefficients, and off-diagonal relaxation matrix element coefficients for line mixing. These line shape parameters were obtained for both self- and air-broadening, and temperature dependences of these parameters were determined where possible. As previously done in studies of CO_2, rather than retrieving individual line positions and intensities, we constrained them to their theoretical relationships, including Herman-Wallis terms, determining only the band intensities and rovibrational constants. The results are discussed and compared with values reported in the literature. K. Sung, A. W. Mantz, M. A. H. Smith, L. R. Brown, T. J. Crawford, V. Malathy Devi and D. C. Benner, JMS 262 (2010) 122-134. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith and D. A. Atkins, JQSRT 53 (1995) 705-721. V. Malathy Devi, D. C. Benner, L. R. Brown, C. E. Miller and R. A. Toth, JMS 242 (2007) 90-117. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  13. 13C-18O bonding (Δ47) in deep-sea corals: a calibration study

    NASA Astrophysics Data System (ADS)

    Kimball, J. B.; Tripati, A.; Dunbar, R. B.; Eagle, R.

    2013-12-01

    Deep-sea corals are a potentially valuable archive of temperature in intermediate and deep waters, regions for which a paucity of temperature data exists. These archives could give valuable insight into the natural variability of areas of the ocean that play an active role in large-scale climate dynamics. Due to significant 'vital effects' (i.e., non-equilibrium mineral compositions) in δ18O, however, deep-sea coral have been challenging to develop as a paleotemperature proxy. Clumped-isotope paleothermometry is a new method that may circumvent some of the known complications with δ18O paleotemperature analysis in deep-sea coral. This geothermometer is based on the ordering of heavy 13C-18O ';clumps' in carbonate minerals. Initial calibration studies have shown that the method is independent from the solution chemistry of the precipitating fluids as well as 'vital effects' in deep-sea corals and other types of carbonates. Some kinetic effects have been observed in tropical corals and speleothems. Here we report new data in order to further develop clumped isotopes as a paleothermometer in deep-sea corals as well as to investigate taxon-specific effects. 13C-18O bond ordering was analyzed in live-collected scleractinian (Enallopsammia sp.) and gorgonian (Isididae and Coralliidae) deep-sea corals. We determined mass 47 anomalies in samples (Δ47), which refers to the parts per thousand excess of 13C-18O-16O in CO2 produced on acid digestion of a sample, relative to the amount predicted to be present if isotopes were randomly distributed amongst all CO2 isotopologues. Measured Δ47 values were compared to in situ temperatures and the relationship between Δ47 and temperature was determined for each group to investigate taxon-specific effects.

  14. Air-Broadened Line Parameters for the 2←0 Bands of 13C16O and 12C18O at 2.3 μm

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Smith, M. A. H.; Mantz, A. W.; Sung, K.; Brown, L. R.

    2012-06-01

    Air-broadened line shape parameters were determined for the first time in the 2←0 bands of 13C16O near 4166.8 cm-1 and 12C18O near 4159.0 cm-1. Spectra were recorded at 0.005 cm-1 resolution using a coolable absorption cell in the sample compartment of the Bruker IFS 125HR Fourier transform spectrometer at Jet Propulsion Laboratory. Gas temperatures and pressures ranged from 150 to 298 K and 20 to 700 Torr, respectively. Line parameters were determined by broad-band multispectrum least-squares fitting of the 4000-4360 cm-1 region in 16 spectra simultaneously; each set included 4 isotope-enriched pure sample scans and 12 air+CO samples (13CO or C18O, as appropriate). The air-broadened parameters measured were Lorentz half-width coefficients, their temperature dependence exponents; pressure-induced shift coefficients, their temperature dependences; and off-diagonal relaxation matrix elements. Speed dependence parameters were included to minimize the fit residuals. For both isotopologues the individual line positions and intensities were constrained to their theoretical relationships in order to obtain the rovibrational (G, B, D, and H) and band intensity parameters, including Herman-Wallis coefficients. The results for 13C16O and 12C18O are compared with those for the 12C16O 2←0 band and discussed. K. Sung, A. W. Mantz, M. A. H. Smith, et al., JMS 262 (2010) 122-134. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith and D. A. Atkins, JQSRT 53 (1995) 705-721. V. Malathy Devi, D. C. Benner, L. R. Brown, C. E. Miller and R. A. Toth, JMS 242 (2007) 90-117. V. Malathy Devi, D. C. Benner, M. A. H. Smith, et al., JQSRT (2012) in press. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  15. Theoretical Calibration on the 13C-18O Clumped Isotope Thermometer

    NASA Astrophysics Data System (ADS)

    Tang, M.; Zhang, S. T.; LIU, Q.; Liu, Y.

    2014-12-01

    The kinetic isotope effect (KIE) arisen from phosphoric acid digestion of carbonates has been noticed since the beginning of stable isotope geochemistry. However, the molecular level details of this reaction have not been fully understood yet. Equilibrium 13C-18O clumped isotope distribution in carbonates has been suggested as a new thermometer for surface temperature systems; nevertheless, existing Δ47-T relationships calibrated by several different groups are incompatible, generating substantial confusions and debates about those variations. Here we propose a new molecular-level mechanism with three parallel pathways for the phosphoric acid digestion of carbonates. We show that the KIE of such reaction can be different if the relative contributions of the three parallel pathways are changed. This new mechanism abandons completely a previously proposed molecular mechanism (i.e., Guo et al., 2009) and can explain (at least partly) why the Δ47-T relationships provided by different groups are different. Together with a re-calculated equilibrium clumped isotope fractionation factors of carbonate minerals using a new volume-variable-cluster-model method with higher theoretical-level treatments and higher-order anharmonic corrections, we present a theoretical (equilibrium + KIE) Δ47-T relationship for carbonates. Our theoretical calibration line is with large variations due to considering possible changes of relative contributions of the three parallel pathways and different carbonate mineral used. For minimizing the variation, we suggest using the same amount of sample, the same mineral and the same temperature of phosphoric acid digestion for this experiment.

  16. LED-based Fourier transform spectroscopy of 16O12C18O and 12C18O2 in the 11,260-11,430 cm-1 range

    NASA Astrophysics Data System (ADS)

    Serdyukov, V. I.; Sinitsa, L. N.; Lugovskoi, A. A.; Borkov, Yu. G.; Tashkun, S. A.; Perevalov, V. I.

    2016-07-01

    The absorption spectrum of the 16O12C18O and 12C18O2 carbon dioxide isotopologues has been recorded in the 11,260- 11,430 cm-1 spectral range using Bruker IFS 125 HR Fourier transform spectrometer with resolution 0.05 cm-1 at temperature 297 K and path length 24 m. The 18O enriched sample of carbon dioxide at total pressure 96.5 mbar was used for these purposes. The spectrometer used LED emitter as a light source. This gave possibility to reach the minimal detectable absorption coefficient αmin~1.4×10-7 cm-1 using 23,328 scans. In the recorded spectrum we have assigned the 00051-00001 band for both 16O12C18O and 12C18O2 isotopologues using the predictions performed within the framework of the method of effective operators. The line positions and intensities of the observed bands are found. The comparison of the observed and predicted line positions and intensities is performed confirming good accuracy of the predictions. The spectroscopic parameters for the observed bands are determined.

  17. Preferential formation of 13C- 18O bonds in carbonate minerals, estimated using first-principles lattice dynamics

    NASA Astrophysics Data System (ADS)

    Schauble, Edwin A.; Ghosh, Prosenjit; Eiler, John M.

    2006-05-01

    Equilibrium constants for internal isotopic exchange reactions of the type: Ca12C18O16O2+Ca13C16O3↔Ca13C18O16O2+Ca12C16O3 for individual CO 32- groups in the carbonate minerals calcite (CaCO 3), aragonite (CaCO 3), dolomite (CaMg(CO 3) 2), magnesite (MgCO 3), witherite (BaCO 3), and nahcolite (NaHCO 3) are calculated using first-principles lattice dynamics. Calculations rely on density functional perturbation theory (DFPT) with norm-conserving planewave pseudopotentials to determine the vibrational frequencies of isotopically substituted crystals. Our results predict an ˜0.4‰ excess of 13C18O16O22- groups in all studied carbonate minerals at room-temperature equilibrium, relative to what would be expected in a stochastic mixture of carbonate isotopologues with the same bulk 13C/ 12C, 18O/ 16O, and 17O/ 16O ratios. The amount of excess 13C18O16O22- decreases with increasing temperature of equilibration, from 0.5‰ at 0 °C to <0.1‰ at 300 °C, suggesting that measurements of multiply substituted isotopologues of carbonate could be used to infer temperatures of ancient carbonate mineral precipitation and alteration events, even where the δ 18O of coexisting fluids is uncertain. The predicted temperature sensitivity of the equilibrium constant is ˜0.003‰/°C at 25 °C. Estimated equilibrium constants for the formation of 13C18O16O22- are remarkably uniform for the variety of minerals studied, suggesting that temperature calibrations will also be applicable to carbonate minerals not studied here without greatly compromising accuracy. A related equilibrium constant for the reaction: Ca12C18O16O2+Ca12C17O16O2↔Ca12C18O17O16O+Ca12C16O3 in calcite indicates formation of 0.1‰ excess 12C 18O 17O 16O 2- at 25 °C. In a conventional phosphoric acid reaction of carbonate to form CO 2 for mass-spectrometric analysis, molecules derived from 13C18O16O22- dominate (˜96%) the mass 47 signal, and 12C 18O 17O 16O 2- contributes most of the remainder (3%). This suggests

  18. Efficient Total Chemical Synthesis of (13) C=(18) O Isotopomers of Human Insulin for Isotope-Edited FTIR.

    PubMed

    Dhayalan, Balamurugan; Fitzpatrick, Ann; Mandal, Kalyaneswar; Whittaker, Jonathan; Weiss, Michael A; Tokmakoff, Andrei; Kent, Stephen B H

    2016-03-01

    Isotope-edited two-dimensional Fourier transform infrared spectroscopy (2 D FTIR) can potentially provide a unique probe of protein structure and dynamics. However, general methods for the site-specific incorporation of stable (13) C=(18) O labels into the polypeptide backbone of the protein molecule have not yet been established. Here we describe, as a prototype for the incorporation of specific arrays of isotope labels, the total chemical synthesis-via a key ester insulin intermediate-of 97 % enriched [(1-(13) C=(18) O)Phe(B24) ] human insulin: stable-isotope labeled at a single backbone amide carbonyl. The amino acid sequence as well as the positions of the disulfide bonds and the correctly folded structure were unambiguously confirmed by the X-ray crystal structure of the synthetic protein molecule. In vitro assays of the isotope labeled [(1-(13) C=(18) O)Phe(B24) ] human insulin showed that it had full insulin receptor binding activity. Linear and 2 D IR spectra revealed a distinct red-shifted amide I carbonyl band peak at 1595 cm(-1) resulting from the (1-(13) C=(18) O)Phe(B24) backbone label. This work illustrates the utility of chemical synthesis to enable the application of advanced physical methods for the elucidation of the molecular basis of protein function. PMID:26715336

  19. Body temperatures of modern and extinct vertebrates from 13C-18O bond abundances in bioapatite

    PubMed Central

    Eagle, Robert A.; Schauble, Edwin A.; Tripati, Aradhna K.; Tütken, Thomas; Hulbert, Richard C.; Eiler, John M.

    2010-01-01

    The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms and to reconstruct past climate. Here we report the application of a new type of geochemical measurement to bioapatite, a “clumped-isotope” paleothermometer, based on the thermodynamically driven preference for 13C and 18O to bond with each other within carbonate ions in the bioapatite crystal lattice. This effect is dependent on temperature but, unlike conventional stable isotope paleothermometers, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of 13C-18O bonds in the carbonate component of tooth bioapatite from modern specimens decreases with increasing body temperature of the animal, following a relationship between isotope “clumping” and temperature that is statistically indistinguishable from inorganic calcite. This result is in agreement with a theoretical model of isotopic ordering in carbonate ion groups in apatite and calcite. This thermometer constrains body temperatures of bioapatite-producing organisms with an accuracy of 1–2 °C. Analyses of fossilized tooth enamel of both Pleistocene and Miocene age yielded temperatures within error of those derived from similar modern taxa. Clumped-isotope analysis of bioapatite represents a new approach in the study of the thermophysiology of extinct species, allowing the first direct measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurement of clumped isotopes in phosphorites and fossils has the potential to reconstruct environmental temperatures. PMID:20498092

  20. VizieR Online Data Catalog: G53.541-0.011 12CO and 13CO data cu

    NASA Astrophysics Data System (ADS)

    Xu, J. L.; Lu, B. G.

    2014-07-01

    The mapping observations of HII region G53.54-0.01 and its adjacent region were performed in the 12CO J=1-0, 13CO J=1-0, and C18O J=1-0 lines using the Purple Mountain Observation (PMO) 13.7m radio telescope at De Ling Ha in the west of China at an altitude of 3200 meters, in May 2013. (2 data files).

  1. Air-broadened line parameters with temperature dependence for 12C16O, 13C16O, and 12C18O at 2.3 μm

    NASA Astrophysics Data System (ADS)

    Smith, M. H.; Malathy Devi, V.; Benner, D.; Mantz, A. W.; Sung, K.; Brown, L. R.

    2012-12-01

    To improve the spectroscopic database for remote sensing of tropospheric CO, we have recorded more than 50 high resolution (0.005 cm-1) spectra of CO and two of its isotopologues (13CO and C18O) at temperatures between 150 and 298 K using a coolable absorption cell in the sample compartment of the Bruker IFS 125HR Fourier transform spectrometer at Jet Propulsion Laboratory. Air-broadened spectra at total pressures up to 700 Torr were recorded for all three isotopologues, and self-broadened CO spectra were also recorded. Line parameters were determined by broad-band constrained multispectrum least-squares fitting of 16 or more spectra simultaneously. Parameters determined in the fits included Lorentz half-width coefficients, their temperature dependence exponents; pressure-induced line shift coefficients, their temperature dependences; and the off-diagonal relaxation matrix elements that characterize line mixing. Speed dependence parameters were also included to minimize the fit residuals. The individual line positions and intensities were constrained to their theoretical relationships in order to obtain the rovibrational (G, B, D, and H) and band intensity parameters, including Herman-Wallis coefficients, as has been done for CO2 previously. The air-broadening results for the 13C16O and 12C18O 2-0 bands are compared with each other and with those for the corresponding 12C16O band.

  2. Protostellar accretion traced with chemistry. Comparing synthetic C18O maps of embedded protostars to real observations

    NASA Astrophysics Data System (ADS)

    Frimann, S.; Jørgensen, J. K.; Padoan, P.; Haugbølle, T.

    2016-02-01

    Context. Understanding how protostars accrete their mass is a central question of star formation. One aspect of this is trying to understand whether the time evolution of accretion rates in deeply embedded objects is best characterised by a smooth decline from early to late stages or by intermittent bursts of high accretion. Aims: We create synthetic observations of deeply embedded protostars in a large numerical simulation of a molecular cloud, which are compared directly to real observations. The goal is to compare episodic accretion events in the simulation to observations and to test the methodology used for analysing the observations. Methods: Simple freeze-out and sublimation chemistry is added to the simulation, and synthetic C18O line cubes are created for a large number of simulated protostars. The spatial extent of C18O is measured for the simulated protostars and compared directly to a sample of 16 deeply embedded protostars observed with the Submillimeter Array. If CO is distributed over a larger area than predicted based on the protostellar luminosity, it may indicate that the luminosity has been higher in the past and that CO is still in the process of refreezing. Results: Approximately 1% of the protostars in the simulation show extended C18O emission, as opposed to approximately 50% in the observations, indicating that the magnitude and frequency of episodic accretion events in the simulation is too low relative to observations. The protostellar accretion rates in the simulation are primarily modulated by infall from the larger scales of the molecular cloud, and do not include any disk physics. The discrepancy between simulation and observations is taken as support for the necessity of disks, even in deeply embedded objects, to produce episodic accretion events of sufficient frequency and amplitude.

  3. VizieR Online Data Catalog: C18O/C17O ratios in the Galactic center

    NASA Astrophysics Data System (ADS)

    Zhang, J. S.; Sun, L. L.; Riquelme, D.; Henkel, C.; Lu, D. R.; Zhang, Y.; Wang, J. Z.; Wang, M.; Li, J.

    2015-09-01

    Our mapping observations of the J=1-0 lines of 12CO, 13 and C17O were carried out with the DLH 13.7m telescope of the Purple Mountain Observatory (PMO) at Delingha in 2011 January and 2012 May and November. The C18O and C17O lines were also observed in single-point mode toward Sgr B2 with the IRAM 30m telescope in 2011 September, and toward Sgr C and Sgr D with the Mopra 22m in 2014 June. (2 data files).

  4. Biomolecules from HCN

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Wos, J. D.; Ryan, T. J.; Lobo, A. P.; Donner, D. B.

    1974-01-01

    It has been suggested by Sanchez et al. (1967) that HCN might have been one of the more important precursors of biological molecules on the primitive earth. Studies were conducted to determine the mechanisms involved in HCN oligomerizations in dilute aqueous solutions and to identify the compounds which are produced in these oligomerization mixtures. Indirect evidence for the formation of cyanate was obtained along with direct evidence for the formation of citrulline, aspartic acid, and orotic acid.

  5. Oscillator Strengths and Predissociation Rates for W-X Bands and the 4P5P Complex in 13C18O

    NASA Astrophysics Data System (ADS)

    Eidelsberg, Michele; Lemaire, Jean Louis; Federman, Steven; Stark, Glenn; Heays, Alan; Gavilan, Lisseth; Lyons, James R.; Smith, Peter L.; de Oliveira, Nelson; Joyeux, Denis

    2015-06-01

    In our ongoing experiments on the DESIRS beam-line at the SOLEIL Synchrotron, we are acquiring the necessary data on oscillator strengths and predissociation rates for modeling CO photochemistry in astronomical environments. A VUV Fourier Transform Spectrometer with a resolving power of about 350,000 allows us to discern individual lines in electronic transitions. Here we focus on results obtained from absorption spectra of 13C18O, for the W ^1Π - X ^1σ^+ bands with v'=0, 2, {and} 3 and v''=0 and three resolved bands involving transitions to the upper levels 4pπ(2), 5pπ(0), and 5pσ(0) of the 4p(2) and 5p(0) complexes. We compare our results with earlier determinations for this isotopologue of CO, as well as with our SOLEIL measurements on 12C16O, 13C16O, and 12C18O.

  6. Three Millimeter Molecular Line Observations of Sagittarius B2. II. High-Resolution Studies of C 18O, HNCO, NH 2CHO, and HCOOCH 3

    NASA Astrophysics Data System (ADS)

    Kuan, Yi-Jehng; Snyder, Lewis E.

    1996-10-01

    High-resolution imaging of C18O, HNCO, NR2CHO, and RCOOCH3 in Sgr B2 are presented in this study. The C18O emission comes mainly from the Sgr B2(M) and Sgr B2(N) dense cores and the western gas clump RNO(M). Toward Sgr B2(M), the C18O column density is 2 times higher and the fractional abundance is 80 times higher than toward Sgr B2(N). In HNO(M), the narrow line width implies that the C18O emission arises from the diffuse gas. The complex molecules NR2CHO and HCOOCR3 were detected only toward the Sgr B2(N) core. The HNCO K-1 = 2 emission is detected only in Sgr B2(N) and is attributed to efficient radiative pumping, which indicates the significant presence of far-infrared field and warm dust grains. Only 4% of the HNCO was found in the K-1 = 0 ladders in Sgr B2(N). The nondetection of the K-1 = 2 emission toward Sgr B2(M) is caused by excitation and low abundance. In contrast, the HNCO K-1 = 0 emission comes mainly from the extended gas component: the far northern region and HNCO(SW). For the K-1 = 0 transitions, Trot = ˜7 K. The low Trot and the apparent ubiquity of RNCO suggest that abundant HNCO exists in the Sgr B2 envelope. The HNCO K-1 = 0 emission unveiled two spatially extended velocity components; the velocity gap between them covers the same LSR velocities of the Sgr B2 dense cores. If HNCO is formed via surface reactions, the pervasive detection of HNCO in the outer edges of Sgr B2 cloud core leads to the cloud-cloud collision postulate. A north-south C18O bipolar structure was seen in Sgr B2(M) centered at the compact H II region F. The bipolar structure appears asymmetric and thus favors the outflow interpretation. The sharp outer edges of the C18O line profiles of the two lobes further support the outflow picture. The estimated outflow age is ˜2±1 x 104 yr, and the total mass is ˜1700 Msun. The outflow masses for the blue and red lobes are <360 Msun and <410 Msun, respectively. The mass-loss rate is thus <0.037 Msun yr-1. The detection of

  7. 1300 micron continuum and C18O line mapping of giant molecular cloud cores. II. W3, NGC 2264, NGC 6334I, RHO Ophiuchi and S140.

    PubMed

    Schwartz, P R; Snell, R L; Schloerb, F P

    1989-01-01

    In this paper we present nearly simultaneous 1300 microns continuum and J = 2-1 C18O maps of the cores of five molecular clouds, W3, NGC 2264, NGC 6334I, rho Oph, and S140. The purpose of this experiment was to compare these two column density tracers. We find that dust continuum and C18O emission are equally effective tracers of column density in molecular cloud cores and give a good indication of cloud structure. When the maps are analyzed in terms of the quantity q = Q/[a rho RX(C18O)], we find that q does not vary by much more than an order of magnitude either within objects or from object to object, implying that nominal dust parameters of absorption efficiency, radius, and gas-to-dust ratio and CO abundance are on average correct in a variety of sources. We did detect source-to-source variations in q. This variation could be either in the dust-to-CO number density ratio or in grain parameters. These variations are not well correlated with total source luminosity, average or typical temperature, or total column density. The best example of this variation appears to be rho Oph where q is about a factor of 7 lower than is typically found. Our approach is analogous to the study of the A nu to CO ratio and is probably equivalent to extending this study to large A nu if the same grains are responsible for both optical opacity and far-infrared to millimeter-wave emission. There is no fundamental reason to expect A nu/NCO or q to be constant and, in fact, we have found that it is not constant in even a small source sample. PMID:11538349

  8. Predicting Effects of Cations (Mg, Ca, Na, and K) on 13C-18O Clumping in Dissolved Inorganic Carbon Species and Implications for Carbonate Geothermometry

    NASA Astrophysics Data System (ADS)

    Hill, P. S.; Tripati, A.; Schauble, E. A.

    2014-12-01

    13C-18O bond abundance in carbonates is becoming more widely used as a geothermometer; this proxy is affected by various environmental factors. Here we report the influence of cations (Mg2+, Ca2+, Na+, and K+) at high concentrations (~2 mol/liter) on the isotopologue composition of the DIC pool. Clumped isotope fractionation in CO32- groups of dissolved species and carbonate minerals is reported using the notation Δ63 corresponding mainly to the enrichment in per mil of Hx13C18O16O2x-2 (plus Hx12C18O17O 16Ox-2, Hx12C17O17O 17Ox-2, and Hx13C17O17O 16Ox-2) above the amount expected for a random distribution of isotopes among all CO32-, HCO3- and H2CO3 isotopologues. The Δ63 of a solution of dissolved inorganic carbon (DIC) depends upon the relative abundances of each DIC species (CO2(aq) or H2CO3, HCO3-, and CO32-) since each DIC species has a distinct equilibrium clumped isotope signature. These abundances depend primarily upon solution pH and secondarily upon temperature and salinity (fresh water vs. sea water vs. brine). Solvated DIC species with additional ions and the composite DIC solutions were modeled as a series of supermolecular clusters, each with a single DIC molecule, an added cation, and 21 to 32 surrounding H2O molecules. As in our previous work (Hill et al., 2014, GCA 125, 610-652), we developed electronic structure models at different levels of theory to ensure the best possible reliability at reasonable computational efficiency. Overall, the models predict that common aqueous cations will slightly increase the 13C-18O clumping signature of both individual DIC species and the total DIC pool at a given pH, salinity, and temperature. Predicted Δ63values are also dependent upon cation concentration. The perturbing effect of Mg2+ > Ca2+ > K+ > Na+. Dissolved cations increase the clumped crossover pH (pH at which the composite Δ63 of the DIC pool equals the Δ63 of calcite at equilibrium). Our models predict that a DIC solution of low to moderate p

  9. A paleothermometer based on abundances of 13C-18O bonds in bioapatite: Calibration and reconstruction of the body temperatures of extinct Cenozoic mammals and Mesozoic dinosaurs

    NASA Astrophysics Data System (ADS)

    Eagle, R.; Schauble, E. A.; Tripati, A. K.; Fricke, H. C.; Tuetken, T.; Eiler, J. M.

    2009-12-01

    The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms, and to reconstruct past climate in terrestrial and marine settings. Here we report the application of a new type of geochemical measurement to bioapatite, a ‘clumped isotope’ thermometer based on the thermodynamically driven preference for 13C and 18O to bond with each other within carbonate ions in the crystal lattice of apatite. This effect is dependent on temperature but unlike conventional stable isotope paleotemperature proxies, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of 13C-18O bonds in the carbonate component of apatite from modern teeth is proportional to the body temperature of the organism, with an accuracy of 1-2oC, and that the empirical calibration is supported by a theoretical model of isotopic ordering. We also report initial paleothermometry results from analyses of Cenozoic fossil mammal teeth and Mesozoic dinosaur teeth. Therefore, clumped isotope analysis of bioapatite represents a new approach in the study of the physiology of extinct species by allowing the first relatively assumption-free measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurements of clumped isotopes in apatite from fossils, such as conodonts and brachiopods, as well as phosphorites, have the potential to record environmental temperatures.

  10. Oscillator strengths for transitions to Rydberg levels in 12C 16O, 13C 16O and 13C 18O between 967 and 972 Å

    NASA Astrophysics Data System (ADS)

    Eidelsberg, M.; Lemaire, J. L.; Fillion, J. H.; Rostas, F.; Federman, S. R.; Sheffer, Y.

    2004-09-01

    Absorption oscillator strengths have been determined from high-resolution spectra in the 967-972 Å region of three CO isotopomers for transitions to the Rydberg levels 4pπ(0), 3dπ(1)b and 4pσ(0), as well as to the mixed E(6) level recently characterized by Eidelsberg et al. (\\cite{Eid04}). Synchrotron radiation from the Super-ACO electron storage ring at Orsay (LURE) was used as a light source. Oscillator strengths were extracted from the recorded spectra by least-squares fitting of the experimental profiles with synthetic spectra taking into account the homogeneous and heterogeneous interactions of the four levels. Column densities were derived from fits to the 3pπ(0) absorption band whose oscillator strength is well established. These are the first reported measurements for 13C18O. For 12C16Op, our results are consistent with the larger values obtained in the most recent laboratory and astronomical studies. Based on experiments done at the Super-ACO electron storage ring at Orsay (LURE), France.

  11. Dysfunctional HCN ion channels in neurological diseases

    PubMed Central

    DiFrancesco, Jacopo C.; DiFrancesco, Dario

    2015-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current) in heart and Ih in neurons. HCN channels contribute in several ways to neuronal activity and are responsible for many important cellular functions, including cellular excitability, generation, and modulation of rhythmic activity, dendritic integration, transmission of synaptic potentials, and plasticity phenomena. Because of their role, defective HCN channels are natural candidates in the search for potential causes of neurological disorders in humans. Several data, including growing evidence that some forms of epilepsy are associated with HCN mutations, support the notion of an involvement of dysfunctional HCN channels in different experimental models of the disease. Additionally, some anti-epileptic drugs are known to modify the activity of the Ih current. HCN channels are widely expressed in the peripheral nervous system and recent evidence has highlighted the importance of the HCN2 isoform in the transmission of pain. HCN channels are also present in the midbrain system, where they finely regulate the activity of dopaminergic neurons, and a potential role of these channels in the pathogenesis of Parkinson’s disease has recently emerged. The function of HCN channels is regulated by specific accessory proteins, which control the correct expression and modulation of the neuronal Ih current. Alteration of these proteins can severely interfere with the physiological channel function, potentially predisposing to pathological conditions. In this review we address the present knowledge of the association between HCN dysfunctions and neurological diseases, including clinical, genetic, and physiopathological

  12. Morphology and kinematics of the gas envelope of protostar L1527 as obtained from ALMA observations of the C18O(2-1) line emission

    NASA Astrophysics Data System (ADS)

    Tuan-Anh, P.; Nhung, P. T.; Hoai, D. T.; Diep, P. N.; Phuong, N. T.; Thao, N. T.; Darriulat, P.

    2016-09-01

    Using ALMA observations of the C18O(2-1) line emission of the gas envelope of protostar L1527, we have reconstructed its morphology and kinematics under the assumption of axisymmetry about the west-east axis. The main original contribution to our understanding of the formation process of L1527 is the presentation of a simple 3D parameterisation based solely on regions that are not dominated by absorption. In the explored range (˜0.7 to 5 arcsec from the star) the model reproduces observations better than earlier attempts. The main results include: a measurement of the rotation velocity that confirms its evolution to Keplerian toward short distances; a measurement of the mean in-fall velocity, 0.43±0.10 km s-1, lower than free fall velocity, with no evidence for the significant r-dependence suggested by an earlier analysis; a measurement of the central mass, 0.23±0.06 M⊙ within a distance of 1.5 arcsec from the star, in agreement with earlier estimates obtained from a different range of distances; evidence for a strong disc plane depression of the in-falling flux resulting in an X shaped flow possibly caused by the freeze-out of CO molecules on dust grains; a measurement of the accretion rate, 3.5±1.0 10-7M⊙ yr-1at a distance of 1 arcsec (140 au) from the star; evidence for a 10° tilt of the symmetry plane of the envelope about the line of sight, cancelling below ˜3 arcsec from the star, but matching infrared observations and being also apparent on the sky map of the mean Doppler velocity.

  13. Discrimination against C18O16O during photosynthesis and the oxygen isotope ratio of respired CO2 in boreal forest ecosystems

    NASA Astrophysics Data System (ADS)

    Flanagan, Lawrence B.; Brooks, J. Renee; Varney, Gregory T.; Ehleringer, James R.

    1997-03-01

    Our objective was to analyze factors that influence changes in the oxygen isotope ratio (δ18O) of atmospheric CO2 within boreal forest ecosystems. We made measurements in the three major forest types (black spruce, jack pine, and aspen) at the southern and northern ends of the boreal forest in central Canada. This research was part of a larger study, the Boreal Ecosystem-Atmosphere Study (BOREAS). In terrestrial ecosystems the δ18O value of atmospheric CO2 is strongly influenced by isotope effects that occur during photosynthesis and respiration. Of primary importance is an equilibrium isotope effect that occurs between oxygen in CO2 and oxygen in soil water and plant chloroplast water. During the equilibrium reaction the oxygen isotope ratio of CO2 becomes enriched in 18O relative to that of water. We measured seasonal changes in the oxygen isotope ratio of (1) water input to the ecosystems (precipitation), (2) water taken up by the major plant species from the soil (plant stem water), and (3) water in plant leaves. We used this information in calculations of isotope discrimination during photosynthesis and soil respiration. Discrimination against C18O16O during photosynthetic gas exchange (ΔA) (influenced by equilibration with chloroplast water) averaged approximately 21‰ at midday and was similar for all forest types. In contrast, CO2 released during plant and soil respiration had an average δ18O value of -14.4‰ but was less depleted in 18O than would be expected for respired CO2 in isotopic equilibrium with soil water. This effect was most pronounced in black spruce sites because of the extensive coverage of moss on the ground surface and the observation that water in the upper moss layers can have an oxygen isotope ratio substantially different from water in deeper soil layers.

  14. FT-IR spectra of 18O-, and 13C-enriched CO2 in the ν3 region: High accuracy frequency calibration and spectroscopic constants for 16O12C18O, 18O12C18O, and 16O13C16O

    NASA Astrophysics Data System (ADS)

    Elliott, Ben M.; Sung, Keeyoon; Miller, Charles E.

    2015-06-01

    In this report, we extend our Fourier transform infrared (FT-IR) spectroscopy measurements of CO2 in the ν3 region (2200-2450 cm-1, 65-75 THz) to the 18O-, and 13C-substituted isotopologues, using the JPL Bruker IFS-125HR Fourier Transform Spectrometer (JPL-FTS). High quality (S/N ∼ 2000) spectra were obtained separately for each of the 18O-, and 13C-isotopically enriched samples. The absolute wavenumber accuracies were better than 3 × 10-6 cm-1 (∼100 kHz) for strong, isolated transitions, calibrated against the highest accuracy reported CO and 16O12C16O (626) frequency measurements. The JPL-FTS performance and calibration procedure is shown to be reliable and consistent, achievable through vigorous maintenance of the optical alignment and regular monitoring of its instrumental line shape function. Effective spectroscopic constant fits of the 00011 ← 00001 fundamental bands for 16O12C18O (628), 18O12C18O (828), and 16O13C16O (636) were obtained with RMS residuals of 2.9 × 10-6 cm-1, 2.8 × 10-6 cm-1, and 2.9 × 10-6 cm-1, respectively. The observed bands encompassed 79 lines over the Jmax range of P67/R67, 47 lines over P70/R62, and 60 lines over P70/R70 for 628, 828, and 636, respectively. These results complement our recent work on the 17O-enriched isotopologues (Elliott et al., 2014), providing additional high-quality frequency measurements for atmospheric remote sensing applications.

  15. Flavonoid Regulation of HCN2 Channels*

    PubMed Central

    Carlson, Anne E.; Rosenbaum, Joel C.; Brelidze, Tinatin I.; Klevit, Rachel E.; Zagotta, William N.

    2013-01-01

    The hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are pacemaker channels whose currents contribute to rhythmic activity in the heart and brain. HCN channels open in response to hyperpolarizing voltages, and the binding of cAMP to their cyclic nucleotide-binding domain (CNBD) facilitates channel opening. Here, we report that, like cAMP, the flavonoid fisetin potentiates HCN2 channel gating. Fisetin sped HCN2 activation and shifted the conductance-voltage relationship to more depolarizing potentials with a half-maximal effective concentration (EC50) of 1.8 μm. When applied together, fisetin and cAMP regulated HCN2 gating in a nonadditive fashion. Fisetin did not potentiate HCN2 channels lacking their CNBD, and two independent fluorescence-based binding assays reported that fisetin bound to the purified CNBD. These data suggest that the CNBD mediates the fisetin potentiation of HCN2 channels. Moreover, binding assays suggest that fisetin and cAMP partially compete for binding to the CNBD. NMR experiments demonstrated that fisetin binds within the cAMP-binding pocket, interacting with some of the same residues as cAMP. Together, these data indicate that fisetin is a partial agonist for HCN2 channels. PMID:24085296

  16. Detection of HCN in Pluto's atmosphere

    NASA Astrophysics Data System (ADS)

    Lellouch, Emmanuel; Gurwell, Mark; Butler, Bryan; Moullet, Arielle; Moreno, Raphael; Bockelée-Morvan, Dominique; Biver, Nicolas; Fouchet, Thierry; Lis, Darek; Stern, Alan; Young, Leslie; Young, Eliot; Weaver, Hal; Boissier, Jeremie; Stansberry, John

    2015-11-01

    We report on the first detection of hydrogen cyanide in Pluto's atmosphere, obtained with the ALMA interferometer. ALMA observations of the HCN(4-3) line at 354.505 GHz were conducted on June 12.2 and June 13.15, 2015 at ~0.3" spatial resolution, separating Pluto from Charon, with a 234 kHz spectral sampling. The HCN line was detected on both dates, with a ~100 mJy contrast and a ~0.75 MHz FWHM linewidth. The narrow linewidth and the absence of Lorentzian wings indicate that most of the HCN resides in Pluto's upper atmosphere. As on Titan, HCN is an expected photochemical product in a N2-CH4 atmosphere. Data interpretation in terms of the HCN abundance/vertical distribution and comparison with photochemical models will be presented.

  17. Glacial- interglacial temperature change based on 13C18O carbonate bond with in fish bone otoliths from Red Sea sediments

    NASA Astrophysics Data System (ADS)

    Ghosh, P.; Eiler, J.; Feeney, R.

    2006-12-01

    Determining the past record of temperature and salinity of ocean surface waters is essential for understanding past changes in climate, such as those which occur across glacial-interglacial transitions. As a useful proxy, the clumped isotope of CO2 in carbonate (13C18O16O or ?47) from inorganic precipitation experiment has been shown to reflect surface temperature with high degree of confidence (Ghosh et al., 2006). The last glacial cycle was characterized by climate fluctuations, but the extent of any associated changes in global sea level (or, equivalently, ice volume) remains elusive. High stands of sea level can be reconstructed from dated fossil and isotopic analyses of foraminifera and terapods, and these data are complemented by a compilation of global sea-level estimates based on deep-sea oxygen isotope ratios. Salinity derived from the records of oxygen isotopes ratios, however, contains uncertainties due to lack of information about the sea surface temperature change. Here we used combination of clumped isotopes technique and oxygen isotope measurement from fish otoliths (Myctophiformes; lanternfishes) extracted from two piston cores (Ku et al., 1969) (CH-154 and CH-153) to understand the temperature evolution and salinity variation of Red Sea water (300-800m) during the last 70 k.y. We analyzed well preserved unaltered otoliths from 7 different stratigraphic horizons from sediment core CH-154. Our preliminary observation suggests ~20 degree Celsius differences in sea water temperatures between glacial and interglacial time. We showed that the region has experienced fluctuation in climatic and tectonic processes during glacial interglacial time and the otoliths developed within the fishes captured the information about temperature change and salinity variation. Our results indicate a drop in temperature and restricted exchange of water with the open ocean during glaciations. The Red Sea environment was also highly saline even during the interglacial event

  18. The excitation of HCN and HCO{sup +} in the galactic center circumnuclear disk

    SciTech Connect

    Mills, E. A. C.; Güsten, R.; Requena-Torres, M. A.; Morris, M. R.

    2013-12-10

    We present new observations of HCN and HCO{sup +} in the circumnuclear disk (CND) of the Galaxy, which we obtained with the Atacama Pathfinder Experiment telescope. We mapped emission in rotational lines of HCN J = 3-2, 4-3, and 8-7, as well as of HCO{sup +} J = 3-2, 4-3, and 9-8. We also present spectra of H{sup 13}CN J = 3-2 and 4-3 as well as H{sup 13}CO{sup +} J = 3-2 and 4-3 toward four positions in the CND. Using the intensities of all of these lines, we present an excitation analysis for each molecule using the non-LTE radiative transfer code RADEX. The HCN line intensities toward the northern emission peak of the CND yield log densities (cm{sup –3}) of 5.6{sub −0.6}{sup +0.6}, consistent with those measured with HCO{sup +} as well as with densities recently reported for this region from an excitation analysis of highly excited lines of CO. These densities are too low for the gas to be tidally stable. The HCN line intensities toward the CND's southern emission peak yield log densities of 6.5{sub −0.7}{sup +0.5}, higher than densities determined for this part of the CND with CO (although the densities measured with HCO{sup +}, log [n] = 5.6{sub −0.2}{sup +0.2}, are more consistent with the CO-derived densities). We investigate whether the higher densities we infer from HCN are affected by midinfrared radiative excitation of this molecule through its 14 μm rovibrational transitions. We find that radiative excitation is important for at least one clump in the CND, where we additionally detect the J = 4-3, v {sub 2} = 1 vibrationally excited transition of HCN, which is excited by dust temperatures of ≳125-150 K. If this hot dust is present elsewhere in the CND, it could lower our inferred densities, potentially bringing the HCN-derived densities for the southern part of the CND into agreement with those measured using HCO{sup +} and CO. Additional sensitive, high-resolution submillimeter observations, as well as midinfrared observations, would be

  19. 13. CO'S STATEROOM (CABIN'S QUARTERS), PORT EXTERIOR. NOTE PORTHOLE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. CO'S STATEROOM (CABIN'S QUARTERS), PORT EXTERIOR. NOTE PORTHOLE AND WOODEN FRAME WINDOWS. - U.S. Coast Guard Cutter WHITE LUPINE, U.S. Coast Guard Station Rockland, east end of Tillson Avenue, Rockland, Knox County, ME

  20. Health Code Number (HCN) Development Procedure

    SciTech Connect

    Petrocchi, Rocky; Craig, Douglas K.; Bond, Jayne-Anne; Trott, Donna M.; Yu, Xiao-Ying

    2013-09-01

    This report provides the detailed description of health code numbers (HCNs) and the procedure of how each HCN is assigned. It contains many guidelines and rationales of HCNs. HCNs are used in the chemical mixture methodology (CMM), a method recommended by the department of energy (DOE) for assessing health effects as a result of exposures to airborne aerosols in an emergency. The procedure is a useful tool for proficient HCN code developers. Intense training and quality assurance with qualified HCN developers are required before an individual comprehends the procedure to develop HCNs for DOE.

  1. 13CO Molecular Clouds and Clumps in the Galactic Plane

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Stark, A. A.

    2004-12-01

    Using the 13CO Bell Laboratories Survey for one third of galactic plane, (l, b) = (-5° to 117°, -1° to +1°), and our revised cloud identification code, 13CO clouds have been identified and cataloged as a function of threshold temperature; 1,400 of molecular clouds with 1 K threshold temperature and with a 4-threshold number of pixels, 629 clouds with 2 K threshold temperature, and 263 clouds with 3 K. Clouds with the brightest cores (TR*(13CO) > 3 K) are confined to the 5 Kpc Molecular Ring (l<40°) and l=80° region. In addition to cloud identification, dense clump regions can be located using this 13CO survey and then combined with existing UMass-Stony Brook 12CO data for the first quadrant of the Galactic Plane. Numbers of identified clumps are 3,156 with 0.4 threshold 13CO optical depth, 2,134 with 0.6, 1,190 with 0.8, and 662 with 1.0. It is found that the hot clumps are heavily crowded between l = 10° to 20°. Good correlation is found between 13CO integrated intensity and column density. We discuss some statistical characteristics of clouds, cores, and the column density distribution.

  2. HNC, HCN and CN in Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Pérez-Beaupuits, J. P.; Aalto, S.; Gerebro, H.

    2007-12-01

    Aims:Bright HNC 1-0 emission, rivalling that of HCN 1-0, has been found towards several Seyfert galaxies. This is unexpected since traditionally HNC is a tracer of cold (10 K) gas, and the molecular gas of luminous galaxies like Seyferts is thought to have bulk kinetic temperatures surpassing 50 K. There are four possible explanations for the bright HNC: (a) large masses of hidden cold gas; (b) chemistry dominated by ion-neutral reactions; (c) chemistry dominated by X-ray radiation; and (d) HNC enhanced through mid-IR pumping. In this work, we distinguish the cause of the bright HNC and to model the physical conditions of the HNC and HCN emitting gas. Methods: We have used SEST, JCMT and IRAM 30 m telescopes to observe HNC 3-2 and HCN 3-2 line emission in a selection of 5 HNC-luminous Seyfert galaxies. We estimate and discuss the excitation conditions of HCN and HNC in NGC 1068, NGC 3079, NGC 2623 and NGC 7469, based on the observed 3-2/1-0 line intensity ratios. We also observed CN 1-0 and 2-1 emission and discuss its role in photon and X-ray dominated regions. Results: HNC 3-2 was detected in 3 galaxies (NGC 3079, NGC 1068 and NGC 2623). Not detected in NGC 7469. HCN 3-2 was detected in NGC 3079, NGC 1068 and NGC 1365, it was not detected in NGC 2623. The HCN 3-2/1-0 ratio is lower than 0.3 only in NGC 3079, whereas the HNC 3-2/1-0 ratio is larger than 0.3 only in NGC 2623. The HCN/HNC 1-0 and 3-2 line ratios are larger than unity in all the galaxies. The HCN/HNC 3-2 line ratio is lower than unity only in NGC 2623, which makes it comparable to galaxies like Arp 220, Mrk 231 and NGC 4418. Conclusions: We conclude that in three of the galaxies the HNC emissions emerge from gas of densities n ⪉ 105 cm-3, where the chemistry is dominated by ion-neutral reactions. The line shapes observed in NGC 1365 and NGC 3079 show that these galaxies have no circumnuclear disk. In NGC 1068 the emission of HNC emerges from lower (<105 cm-3) density gas than HCN (>105 cm-3

  3. 13CO Bell Laboratories Survey: 13CO Column Density Distribution of the First Quadrant of the Galactic Plane

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Kim, H. G.; Stark, A. A.

    2000-05-01

    We present the distribution of 13CO column density of the first quadrant (l = 8 - 90) of the Galactic Plane using the 13CO Bell Laboratories Survey and UMass-Stony Brook 12CO Survey. We estimate the column density channel by channel (with a velocity step of 1 km/sec) with LTE assumption, generating the coumn density cube data for the first quadrant. Spatial resoultion is smoothed into 6 arcminute for whole direction. The highest column density is estimated to be 9.3x1016 cm-2 per channel, which is one of the densest part of the Galactic Ring region. Good correaltionship is found between 13CO integrated instensity and column density. We discuss some charateristics of the column density distribution. This work is supported by Creative Initiative Research Fund 99-NZ-01-01-A-31 of the Ministry of Science and Techonology, Republic of Korea.

  4. Comet outbursts and polymers of HCN

    NASA Technical Reports Server (NTRS)

    Rettig, Terrence W.; Tegler, Stephen C.; Pasto, Daniel J.; Mumma, Michael J.

    1992-01-01

    Dramatic cometary outbursts have been noted by observers for many years. These outbursts can sometimes increase the apparent brightness of a comet up to 9 mag and release energy on the order of 10 exp 19 ergs. A number of mechanisms have been suggested for outburst activity; however, none has been generally accepted. HCN is a known constituent of both interstellar icy grain mantles and cometary nuclei, and HCN polymers have been postulated to exist on the dark surface of comets such as P/Halley. Since polymerization is a strongly exothermic process, we investigate the possibility that HCN polymerization can provide the energy needed for outbursts. Polymerization may be continuing in the inhomogeneous interior of comets. In addition, the reactive CN groups in these oligomers can be hydrolyzed and may contribute to CO2 and CO pressure buildup in the interior of comets.

  5. The HNC/HCN ratio in comets.

    PubMed

    Irvine, W M; Dickens, J E; Lovell, A J; Schloerb, F P; Senay, M; Bergin, E A; Jewitt, D; Matthews, H E

    1997-01-01

    The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4-3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced in significant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus. PMID:11543322

  6. The HNC/HCN ratio in comets

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Dickens, J. E.; Lovell, A. J.; Schloerb, F. P.; Senay, M.; Bergin, E. A.; Jewitt, D.; Matthews, H. E.; Ferris, J. P. (Principal Investigator)

    1997-01-01

    The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4-3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced in significant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus.

  7. Chemical Recycling of HCN in Cometary Comae

    NASA Astrophysics Data System (ADS)

    Boice, Daniel C.; Kawakita, Hideyo; Shinnaka, Yoshiharu; Mumma, Michael J.; Kobayashi, Hitomi; Ogawa, Sayuri

    2014-11-01

    Modeling is essential to understand the important physical and chemical processes that occur in cometary comae, especially the relationship between putative parent and daughter molecules, such as, HCN and CN. Photochemistry is a major source of ions and electrons that further initiate key gas-phase reactions, contributing to the plethora of molecules and atoms observed in comets. The effects of photoelectrons that interact via impacts are important to the overall excitation and dissociation processes in the inner coma. We consider the relevant processes in the collision-dominated, inner coma of a comet within a global modeling framework to understand observations of HCN and CN. The CN source(s) must be able to produce highly collimated jets, be consistent with the observed CN parent scale length, and have a production rate consistent with the observed CN production. HCN fulfills these conditions in some comets (e.g., 1P/Halley, Hale-Bopp) while it does not in others (e.g., 8P/Tuttle, 6P/d’Arrest, 73P/S-W3, 2P/Encke, 9P/Temple 1 and C/2007 W1).We investigate the chemistry of HCN with our chemical kinetics coma model including a network with other possible CN parents, as well as a dust component that may be a potential source of CN. It is seen that the major destruction pathways of HCN are via photo dissociation (into H and CN) and protonation with water group ions - primarily H3O+. We point out the intriguing “recycling” of HCN via protonation reactions with H3O+, H2O+, OH+, and subsequent dissociative recombination. It seems that HCN molecules observed in the coma can consist of those initially released from the nucleus and those that are freshly formed at different locations in the coma via these protonation/dissociation reactions. We will investigate implications for reconciling discrepancies between observations of HCN and CN in cometary comae.Acknowledgements: We appreciate support from the NSF Planetary Astronomy Program. This program is partially

  8. Rotational spectra and structures of the C6H6-HCN dimer and Ar3-HCN tetramer

    NASA Astrophysics Data System (ADS)

    Gutowsky, H. S.; Arunan, E.; Emilsson, T.; Tschopp, S. L.; Dykstra, C. E.

    1995-09-01

    A comparative study has been made of the rotational properties of C6H6-HCN and Ar3-HCN, observed with the Balle/Flygare pulsed beam, Fourier transform microwave spectrometer. C6H6-HCN is found to be a prolate symmetric top and Ar3-HCN an oblate one, both with the H in the middle. The rotational constants B0, DJ, and DJK of the parent species are 1219.9108(4) MHz, 1.12(3) kHz, and 18.32(8) kHz for C6H6-HCN, and 886.4878(1) MHz, 10.374(2) kHz, and 173.16(1) kHz for Ar3-HCN. Rotational constants are reported for the isotopic species C6H6-H13CN, -HC15N, and 13CC5H6-HC15N, and for Ar3-HC15N and -DCN. Analysis of the 14N hyperfine interaction χ finds its projection on the figure axis to be -4.223(4) MHz in C6H6-HCN and -1.143(2) in Ar3-HCN. They correspond to average projection angles θ between the HCN and figure axes of 15.2° and 45.3°, respectively. A pseudodiatomic analysis of the rotational constants gives the c.m. to c.m. distance to be 3.96 Å in C6H6-HCN and 3.47 Å in Ar3-HCN. While the rotational properties of C6H6-HCN are ``normal,'' those of Ar3-HCN display a long list of ``abnormalities.'' They include a J-dependent χ(14N) similar to that of Ar-HCN; a very large projection angle θ; large centrifugal distortion including higher-order terms in HJ and HJK; splitting of the K=3 transitions into J-dependent doublets; and the ready observation of an excited vibrational state. These behavioral differences are related qualitatively to the interaction surfaces for the two clusters, calculated with the molecular mechanics for clusters (MMC) model, and discussed. The potential minimum for C6H6-HCN is smooth, circular, steep except for a flat bottom, and deep (1762 cm-1). That for Ar3-HCN is tricuspid, with large gullies, and shallow (507 cm-1). In addition to the dispersion forces, the dominant interaction forming C6H6-HCN is between the benzene quadrupole moment and the HCN dipole moment, a strong 4-2 potential. That in Ar3-HCN is polarization of the spherical Ar

  9. THE NITROGEN ISOTOPIC COMPOSITION OF METEORITIC HCN

    SciTech Connect

    Pizzarello, Sandra

    2014-12-01

    HCN is ubiquitous in extraterrestrial environments and is central to current theories on the origin of early solar system organic compounds such as amino acids. These compounds, observed in carbonaceous meteorites, were likely important in the origin and/or evolution of early life. As part of our attempts to understand the origin(s) of meteoritic CN{sup –}, we have analyzed the {sup 15}N/{sup 14}N isotopic composition of HCN gas released from water extracts of the Murchison meteorite and found its value to be near those of the terrestrial atmosphere. The findings, when evaluated viz-a-viz molecular abundances and isotopic data of meteoritic organic compounds, suggest that HCN formation could have occurred during the protracted water alteration processes known to have affected the mineralogy of many asteroidal bodies during their solar residence. This was an active synthetic stage, which likely involved simple gasses, organic molecules, their presolar precursors, as well as mineral catalysts and would have lead to the formation of molecules of differing isotopic composition, including some with solar values.

  10. Colocalization of HCN Channel Subunits in Rat Retinal Ganglion Cells

    PubMed Central

    Stradleigh, Tyler W.; Ogata, Genki; Partida, Gloria J.; Oi, Hanako; Greenberg, Kenneth P.; Krempely, Kalen S.; Ishida, Andrew T.

    2011-01-01

    The current-passing pore of mammalian hyperpolarization-activated, cyclic nucleotide-gated ("HCN") channels is formed by subunit isoforms denoted HCN1-4. In various brain areas, antibodies directed against multiple isoforms bind to single neurons and the current ("Ih") passed during hyperpolarizations differs from that of heterologously expressed homomeric channels. By contrast, retinal rod, cone, and bipolar cells appear to use homomeric HCN channels. Here, we assess the generality of this pattern by examining HCN1 and HCN4 immunoreactivity in rat retinal ganglion cells, measuring Ih in dissociated cells, and testing whether HCN1 and HCN4 protein coimmunoprecipitate. Nearly half of the ganglion cells in whole-mounted retinae bound antibodies against both isoforms. Consistent with colocalization and physical association, 8-bromo-cAMP shifted the voltage-sensitivity of Ih less than that of HCN4 channels and more than that of HCN1 channels, and HCN1 coimmunoprecipitated with HCN4 from membrane fraction proteins. Lastly, the immunopositive somata ranged in diameter from the smallest to the largest in rat retina, the dendrites of immunopositive cells arborized at various levels of the inner plexiform layer and over fields of different diameters, and Ih activated with similar kinetics and proportions of fast and slow components in small, medium, and large somata. These results show that different HCN subunits colocalize in single retinal ganglion cells, identify a subunit that can reconcile native Ih properties with the previously reported presence of HCN4 in these cells, and indicate that Ih is biophysically similar in morphologically diverse retinal ganglion cells and differs from Ih in rods, cones, and bipolar cells. PMID:21456027

  11. Field Measurements of Respiratory Del13CO2 and Photodegradation

    NASA Astrophysics Data System (ADS)

    van Asperen, H.; Sabbatini, S.; Nicolini, G.; Warneke, T.; Papale, D.; Notholt, J.

    2014-12-01

    Carbon decomposition dynamics have been studied in a variety of ecosystems and its variation can mostly be explained in terms of environmental variables (e.g. temperature and precipitation). However, carbon dynamics in arid, water limited regions have shown to be very different and are still largely unknown. Several studies have indicated the importance of photodegradation, the direct breakdown of organic matter by sunlight, in these arid regions. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure concentrations of CO2, CH4, N2O, CO as well as del13C in CO2. The FTIR was connected to 2 different flux measurement systems: a Flux Gradient system and 2 flux chambers, providing a continuous data set of gas concentrations and biosphere-atmosphere gas fluxes at different heights and scales. Field measurements showed photodegradation induced carbon fluxes. Also, respiratory del13CO2 was determined by use of Keeling plots, and was determined to vary between -25‰ and -21‰. A clear diurnal pattern in respiratory del13CO2 was found, suggesting either different (dominant) respiratory processes between day and night or the effect of diffusive fractionation.

  12. Structural studies on HCN oligomers. [catalysts for prebiotic processes

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Edelson, E. H.; Auyeung, J. M.; Joshi, P. C.

    1981-01-01

    NMR spectral studies on the HCN oligomers suggest the presence of carboxamide and urea groupings. The release of CO2, H2O, HCN, CH3CN, HCONH2 and pyridine on pyrolysis is consistent with the presence of these groupings as well as carboxylic acid groups. No basic primary amine groupings could be detected with fluorescamine. Hydrazinolysis of the HCN oligomers releases 10% of the amino acids normally released by acid hydrolysis. The oligomers give a positive biuret test but this is not due to the presence of peptide bonds. There is no conclusive evidence for the presence of peptide bonds in the HCN oligomers. No diglycine was detected on partial hydrolysis of the HCN oligomers at pH 8.5 suggesting that HCN oligomers were not a source of prebiotic peptides.

  13. Isoform dependent regulation of human HCN channels by cholesterol

    PubMed Central

    Fürst, Oliver; D’Avanzo, Nazzareno

    2015-01-01

    Cholesterol has been shown to regulate numerous ion channels. HCN channels represent the molecular correlate of If or Ih in sinoatrial node (SAN) and neuronal cells. Previous studies have implicated a role for cholesterol in the regulation of rabbit HCN4 channels with effects on pacing in the rabbit SAN. Using electrophysiological and biochemical approaches, we examined the effect of cholesterol modulation on human HCN1, HCN2 and HCN4 isoforms. Patch-clamp experiments uncovered isoform specific differences in the effect of cholesterol on gating kinetics upon depletion by MβCD or mevastatin or enrichment using MβCD/cholesterol. Most dramatically cholesterol had isoform specific effects on mode-shifting, which has been suggested to play a key role in stabilizing firing rate and preventing arrhythmic firing in SAN cells and neurons. Mode-shifting in HCN1 channels was insensitive to cholesterol manipulation, while HCN2 and HCN4 were strongly affected. Trafficking of each isoform to the plasma membrane was also affected by cholesterol modulation differentially between isoforms, however, each isoform remained localized in lipid raft domains after cholesterol depletion. These effects may contribute to the side effects of cholesterol reducing therapies including disrupted heart rhythm and neuropathic pain, as well as the susceptibility of sinus dysfunction in patients with elevated cholesterol. PMID:26404789

  14. Constraints on the factors controlling 13C-18O bond abundances in biologically precipitated carbonates from measurements of marine calcifiers cultured at variable temperature, pH, and salinity

    NASA Astrophysics Data System (ADS)

    Conchas, T. E.; Eagle, R.; Eiler, J. M.; Ries, J. B.; Freitas, P. S.; Hiebenthal, C.; Wanamaker, A. D.; Tripati, A. K.

    2012-12-01

    Marine mollusks and corals are widely used as archives of past climate change; oxygen isotopic composition (δ18O value) of their carbonate minerals is perhaps the most commonly used proxy to reconstruct paleoclimate from these marine calcifiers. However, oxygen isotope paleothermometry of mollusks and corals is complicated by non-equilibrium "vital effects" and variations in seawater pH changes, both of which influence the net fractionation of oxygen isotopes between carbonate and water. Carbonate "clumped isotope" thermometry is an emerging approach that potentially addresses these ambiguities. Here we report measurements of abundance of 13C-18O bonds (described by the measured parameter Δ47) in a variety of marine calcifiers cultured under controlled conditions. Previous studies on biologically precipitated samples such as foraminifera, coccoliths, and corals have shown that Δ47 values are related to calcification temperature with a relationship that is generally similar to inorganic carbonate. However, the influence of effects other than temperature has not been extensively studied and little work has been done to explore the potential for small non-equilibrium effects in cultured specimens that were grown under controlled conditions. In this study, we report δ18O and Δ47 measurements of mollusk specimens that were cultured at several temperatures ranging from 5 to 25°C, as well as different pH and salinity values. We also report data for other marine calcifiers including the temperate coral species Oculina arbuscula and the coralline red algae Neogoniolithon sp., that were cultured at a single temperature but variable pH.

  15. Oscillator Strengths and Predissociation Rates for Rydberg Transitions in 12C16O, 13C16O, and 13C18O Involving the E 1Π, B 1Σ+, and W 1Π States

    NASA Astrophysics Data System (ADS)

    Eidelsberg, M.; Sheffer, Y.; Federman, S. R.; Lemaire, J. L.; Fillion, J. H.; Rostas, F.; Ruiz, J.

    2006-08-01

    One of the processes controlling the interstellar CO abundance and the ratio of its isotopologues is photodissociation. Accurate oscillator strengths and predissociation rates for Rydberg transitions are needed for modeling this process. We present results on absorption from the E 1Π-X 1Σ+ (1-0) and B 1Σ+-X 1Σ+ (6-0) bands at 1051 and 1002 Å, respectively, and the vibrational progression W 1Π-X 1Σ+ (v'-0) bands with v'=0-3 at 972, 956, 941, and 925 Å, respectively. The corresponding spectra were acquired at the high resolution (R~30,000) SU5 beam line at the Super ACO Synchrotron in Orsay, France. Spectra were obtained for the 12C16O, 13C 16O, and 13C18O isotopologues. These represent the most complete set of measurements available. Comparison is made with earlier results, both empirical and theoretical. While earlier determinations of oscillator strengths based on absorption from synchrotron radiation tend to be somewhat smaller than ours, the suite of measurements from a variety of techniques agree for the most part, considering the mutual uncertainties. For the bands studied here, their relative weakness, or their significant line widths arising from predissociation, minimizes potential problems from large optical depths at line center in absorption measurements. Predissociating line widths could generally be extracted from the spectra thanks to the profile simulations used in the analysis. In many cases, these simulations allowed us to consider e and f parity levels separately and to determine the dependence of the width on rotational quantum number, J. Our results are consistent with earlier determinations, especially the widths inferred from laser experiments.

  16. 13CO filaments in the Taurus molecular cloud

    NASA Astrophysics Data System (ADS)

    Panopoulou, G. V.; Tassis, K.; Goldsmith, P. F.; Heyer, M. H.

    2014-11-01

    We have carried out a search for filamentary structures in the Taurus molecular cloud using 13CO line emission data from the Five Colleges Radio Astronomy Observatory survey of ˜100 deg2. We have used the topological analysis tool, Discrete Persistent Structures Extractor (DISPERSE), and post-processed its results to include a more strict definition of filaments that requires an aspect ratio of at least 3:1 and cross-section intensity profiles peaked on the spine of the filament. In the velocity-integrated intensity map only 10 of the hundreds of filamentary structures identified by DISPERSE comply with our criteria. Unlike Herschel analyses, which find a characteristic width for filaments of ˜0.1 pc, we find a much broader distribution of profile widths in our structures, with a peak at 0.4 pc. Furthermore, even if the identified filaments are cylindrical objects, their complicated velocity structure and velocity dispersions imply that they are probably gravitationally unbound. Analysis of velocity channel maps reveals the existence of hundreds of `velocity-coherent' filaments. The distribution of their widths is peaked at lower values (0.2 pc) while the fluctuation of their peak intensities is indicative of stochastic origin. These filaments are suppressed in the integrated intensity map due to the blending of diffuse emission from different velocities. Conversely, integration over velocities can cause filamentary structures to appear. Such apparent filaments can also be traced, using the same methodology, in simple simulated maps consisting of randomly placed cores. They have profile shapes similar to observed filaments and contain most of the simulated cores.

  17. The HNC/HCN ratio in star-forming regions

    SciTech Connect

    Graninger, Dawn M.; Öberg, Karin I.; Herbst, Eric; Vasyunin, Anton I.

    2014-05-20

    HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous observations of the HNC/HCN abundance ratio show that the ratio decreases with increasing temperature, something that standard astrochemical models cannot reproduce. We have undertaken a detailed parameter study on which environmental characteristics and chemical reactions affect the HNC/HCN ratio and can thus contribute to the observed dependence. Using existing gas and gas-grain models updated with new reactions and reaction barriers, we find that in static models the H + HNC gas-phase reaction regulates the HNC/HCN ratio under all conditions, except for very early times. We quantitatively constrain the combinations of H abundance and H + HNC reaction barrier that can explain the observed HNC/HCN temperature dependence and discuss the implications in light of new quantum chemical calculations. In warm-up models, gas-grain chemistry contributes significantly to the predicted HNC/HCN ratio and understanding the dynamics of star formation is therefore key to model the HNC/HCN system.

  18. Simple Organics and Biomonomers Identified in HCN Polymers: An Overview

    PubMed Central

    Ruiz-Bermejo, Marta; Zorzano, María-Paz; Osuna-Esteban, Susana

    2013-01-01

    Hydrogen cyanide (HCN) is a ubiquitous molecule in the Universe. It is a compound that is easily produced in significant yields in prebiotic simulation experiments using a reducing atmosphere. HCN can spontaneously polymerise under a wide set of experimental conditions. It has even been proposed that HCN polymers could be present in objects such as asteroids, moons, planets and, in particular, comets. Moreover, it has been suggested that these polymers could play an important role in the origin of life. In this review, the simple organics and biomonomers that have been detected in HCN polymers, the analytical techniques and procedures that have been used to detect and characterise these molecules and an exhaustive classification of the experimental/environmental conditions that favour the formation of HCN polymers are summarised. Nucleobases, amino acids, carboxylic acids, cofactor derivatives and other compounds have been identified in HCN polymers. The great molecular diversity found in HCN polymers encourages their placement at the central core of a plausible protobiological system. PMID:25369814

  19. Neurophysiology of HCN channels: from cellular functions to multiple regulations.

    PubMed

    He, Chao; Chen, Fang; Li, Bo; Hu, Zhian

    2014-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels are encoded by HCN1-4 gene family and have four subtypes. These channels are activated upon hyperpolarization of membrane potential and conduct an inward, excitatory current Ih in the nervous system. Ih acts as pacemaker current to initiate rhythmic firing, dampen dendritic excitability and regulate presynaptic neurotransmitter release. This review summarizes recent insights into the cellular functions of Ih and associated behavior such as learning and memory, sleep and arousal. HCN channels are excellent targets of various cellular signals to finely regulate neuronal responses to external stimuli. Numerous mechanisms, including transcriptional control, trafficking, as well as channel assembly and modification, underlie HCN channel regulation. In the next section, we discuss how the intracellular signals, especially recent findings concerning protein kinases and interacting proteins such as cGKII, Ca(2+)/CaMKII and TRIP8b, regulate function and expression of HCN channels, and subsequently provide an overview of the effects of neurotransmitters on HCN channels and their corresponding intracellular mechanisms. We also discuss the dysregulation of HCN channels in pathological conditions. Finally, insight into future directions in this exciting area of ion channel research is provided. PMID:24184323

  20. Simple Organics and Biomonomers Identified in HCN Polymers: An Overview.

    PubMed

    Ruiz-Bermejo, Marta; Zorzano, María-Paz; Osuna-Esteban, Susana

    2013-01-01

    Hydrogen cyanide (HCN) is a ubiquitous molecule in the Universe. It is a compound that is easily produced in significant yields in prebiotic simulation experiments using a reducing atmosphere. HCN can spontaneously polymerise under a wide set of experimental conditions. It has even been proposed that HCN polymers could be present in objects such as asteroids, moons, planets and, in particular, comets. Moreover, it has been suggested that these polymers could play an important role in the origin of life. In this review, the simple organics and biomonomers that have been detected in HCN polymers, the analytical techniques and procedures that have been used to detect and characterise these molecules and an exhaustive classification of the experimental/environmental conditions that favour the formation of HCN polymers are summarised. Nucleobases, amino acids, carboxylic acids, cofactor derivatives and other compounds have been identified in HCN polymers. The great molecular diversity found in HCN polymers encourages their placement at the central core of a plausible protobiological system. PMID:25369814

  1. In vitro characterization of HCN channel kinetics and frequency dependence in myocytes predicts biological pacemaker functionality.

    PubMed

    Zhao, Xin; Bucchi, Annalisa; Oren, Ronit V; Kryukova, Yelena; Dun, Wen; Clancy, Colleen E; Robinson, Richard B

    2009-04-01

    The pacemaker current, mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, contributes to the initiation and regulation of cardiac rhythm. Previous experiments creating HCN-based biological pacemakers in vivo found that an engineered HCN2/HCN1 chimeric channel (HCN212) resulted in significantly faster rates than HCN2, interrupted by 1-5 s pauses. To elucidate the mechanisms underlying the differences in HCN212 and HCN2 in vivo functionality as biological pacemakers, we studied newborn rat ventricular myocytes over-expressing either HCN2 or HCN212 channels. The HCN2- and HCN212-over-expressing myocytes manifest similar voltage dependence, current density and sensitivity to saturating cAMP concentrations, but HCN212 has faster activation/deactivation kinetics. Compared with HCN2, myocytes expressing HCN212 exhibit a faster spontaneous rate and greater incidence of irregular rhythms (i.e. periods of rapid spontaneous rate followed by pauses). To explore these rhythm differences further, we imposed consecutive pacing and found that activation kinetics of the two channels are slower at faster pacing frequencies. As a result, time-dependent HCN current flowing during diastole decreases for both constructs during a train of stimuli at a rapid frequency, with the effect more pronounced for HCN2. In addition, the slower deactivation kinetics of HCN2 contributes to more pronounced instantaneous current at a slower frequency. As a result of the frequency dependence of both instantaneous and time-dependent current, HCN2 exhibits more robust negative feedback than HCN212, contributing to the maintenance of a stable pacing rhythm. These results illustrate the benefit of screening HCN constructs in spontaneously active myocyte cultures and may provide the basis for future optimization of HCN-based biological pacemakers. PMID:19171659

  2. Electric discharge synthesis of HCN in simulated Jovian atmospheres

    NASA Astrophysics Data System (ADS)

    Stribling, R.; Miller, S. L.

    1987-10-01

    HCN energy yields (moles J-1) were measured using corona discharge for gas mixtures containing H2, CH4, NH3, with H2/CH4 ratios from 4.4 to 1585. The yields are approximately proportional to the mole fraction of methane in the gas mixture. Assuming that the 3/1 ratio of corona discharge to lightning energy on the Earth applies to Jupiter, HCN column densities from corona discharge could account for approximately 10% of the observed HCN. These estimates are very dependent on the values used for the energy available as lightning on Jupiter and the eddy diffusion coefficients in the region of synthesis.

  3. Optical properties of poly-HCN and their astronomical applications

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Meisse, C.; Tuminello, P. S.

    1994-01-01

    Matthews (1992) has proposed that HCN "polymer" is ubiquitous in the solar system. We apply vacuum deposition and spectroscopic techniques previously used on synthetic organic heteropolymers (tholins), kerogens, and meteoritic organic residues to the measurement of the optical constants of poly-HCN in the wavelength range 0.05-40 micrometers. These measurements allow quantitative comparison with spectrophotometry of organic-rich bodies in the outer solar system. In a specific test of Matthews' hypothesis, poly-HCN fails to match the optical constants of the haze of the Saturnian moon, Titan, in the visible and near-infrared derived from astronomical observations and standard models of the Titan atmosphere. In contrast, a tholin produced from a simulated Titan atmosphere matches within the probable errors. Poly-HCN is much more N-rich than Titan tholin.

  4. DEVELOPMENT OF A MONITOR FOR HCN IN MOBILE SOURCE EMISSIONS

    EPA Science Inventory

    Three real-time monitors for measurement of HCN concentrations in mobile source emissions have been designed, built, tested, and delivered to the Environmental Protection Agency (EPA). The important design parameters for these identical instruments were determined during the firs...

  5. New insights into the characterization of 'insoluble black HCN polymers'.

    PubMed

    Ruiz-Bermejo, Marta; de la Fuente, José L; Rogero, Celia; Menor-Salván, César; Osuna-Esteban, Susana; Martín-Gago, José A

    2012-01-01

    The data presented here provide a novel contribution to the understanding of the structural features of HCN polymers and could be useful in further development of models for prebiotic chemistry. The interpretation of spectroscopic and analytical data, along with previous results reported by other authors, allowed us to propose a mechanism for the aqueous polymerization of HCN from its primary and simplest isolated oligomer, the diaminomaleonitrile (DAMN) tetramer. We suggest that 'insoluble black HCN polymers' are formed by an unsaturated complex matrix, which retains a significant amount of H(2) O and important bioorganic compounds or their precursors. This polymeric matrix can be formed by various motifs of imidazoles and cyclic amides, among others. The robust formation of HCN polymers assayed under several conditions seems to explain the plausible ubiquity of these complex substances in space. PMID:22253100

  6. Theoretical study on the excited states of HCN

    SciTech Connect

    Nayak, Malaya K.; Chaudhuri, Rajat K.; Krishnamachari, S.N.L.G.

    2005-05-08

    In the flash-photolysis of oxazole, iso-oxazole, and thiozole a transient band system was observed in the region 2500-3050 A. This band system was attributed to a meta-stable form of HCN, i.e., either HNC or triplet HCN. Theoretical investigations have been carried out on the ground and excited states of HCN to characterize this and other experimentally observed transitions. The predicted geometries are compared with the experiment and earlier theoretical calculations. The present calculations show that the band system in the region 2500-3050 A corresponds to the transition 4 {sup 3}-A{sup '}<{sup -}1 {sup 3}-A{sup '} of HCN.

  7. Vibrationally Hot HCN in the Laboratory and IRC+10216

    NASA Astrophysics Data System (ADS)

    Pearson, John C.; Yu, Shanshan; Gupta, Harshal; Drouin, Brian J.

    2011-06-01

    HCN has historically been used as a tracer of the dense gas in the in interstellar medium. The envelopes of carbon rich asymptotic giant branch stars are generally rich in HCN; however, the large and generally variable infrared flux emitted by the star enormously complicates the interpretation. HCN in IRC+10216 shows an enormous number of masers and lasers pumped by the central star and often enhanced by line overlaps with other abundant molecules such as acetylene in the infrared. A total of seven laser transitions including two previously unreported transitions associated with the 040-011 interacting bands have been observed. To understand the astronomical observations a study of the radio frequency discharge plasma of CH_4 and N_2 was performed. Rotational transitions of HCN in vibrational states up to 15,000 Cm-1 have been observed including inverted levels and a number of previously undetected states. The spectra from IRC+10216 and the laboratory are presented.

  8. Near Infrared Spectra of H2O/HCN Mixtures

    NASA Technical Reports Server (NTRS)

    Mastrapa, R. M.; Bernstein, M. P.; Sanford, S. A.

    2006-01-01

    Cassini's VIMS has already returned exciting results interpreting spectra of Saturn's icy satellites. The discovery of unidentified features possibly due to CN compounds inspired the work reported here. We wanted to test HCN as a possibility for explaining these features, and also explore how the features of HCN change when mixed with H2O. We have previously noted that mixing H20 and CO2 produces new spectral features and that those features change with temperature and mixing ratio.

  9. On the abundance of non-cometary HCN on Jupiter.

    PubMed

    Moses, Julianne I; Visscher, Channon; Keane, Thomas C; Sperier, Aubrey

    2010-01-01

    Using one-dimensional thermochemical/photochemical kinetics and transport models, we examine the chemistry of nitrogen-bearing species in the Jovian troposphere in an attempt to explain the low observational upper limit for HCN. We track the dominant mechanisms for interconversion of N2-NH3 and HCN-NH3 in the deep, high-temperature troposphere and predict the rate-limiting step for the quenching of HCN at cooler tropospheric altitudes. Consistent with some other investigations that were based solely on time-scale arguments, our models suggest that transport-induced quenching of thermochemically derived HCN leads to very small predicted mole fractions of hydrogen cyanide in Jupiter's upper troposphere. By the same token, photochemical production of HCN is ineffective in Jupiter's troposphere: CH4-NH3 coupling is inhibited by the physical separation of the CH4 photolysis region in the upper stratosphere from the NH3 photolysis and condensation region in the troposphere, and C2H2-NH3 coupling is inhibited by the low tropospheric abundance of C2H2. The upper limits from infrared and submillimetre observations can be used to place constraints on the production of HCN and other species from lightning and thundershock sources. PMID:21302544

  10. Structural Basis for the cAMP-dependent Gating in the Human HCN4 Channel

    SciTech Connect

    X Xu; Z Vysotskaya; Q Liu; L Zhou

    2011-12-31

    Hyperpolarization-activated cAMP-regulated (HCN) channels play important physiological roles in both cardiovascular and central nervous systems. Among the four HCN isoforms, HCN2 and HCN4 show high expression levels in the human heart, with HCN4 being the major cardiac isoform. The previously published crystal structure of the mouse HCN2 (mHCN2) C-terminal fragment, including the C-linker and the cyclic-nucleotide binding domain (CNBD), has provided many insights into cAMP-dependent gating in HCN channels. However, structures of other mammalian HCN channel isoforms have been lacking. Here we used a combination of approaches including structural biology, biochemistry, and electrophysiology to study cAMP-dependent gating in HCN4 channel. First we solved the crystal structure of the C-terminal fragment of human HCN4 (hHCN4) channel at 2.4 {angstrom}. Overall we observed a high similarity between mHCN2 and hHCN4 crystal structures. Functional comparison between two isoforms revealed that compared with mHCN2, the hHCN4 protein exhibited marked different contributions to channel function, such as a {approx}3-fold reduction in the response to cAMP. Guided by structural differences in the loop region between {beta}4 and {beta}5 strands, we identified residues that could partially account for the differences in response to cAMP between mHCN2 and hHCN4 proteins. Moreover, upon cAMP binding, the hHCN4 C-terminal protein exerts a much prolonged effect in channel deactivation that could have significant physiological contributions.

  11. A 13CO Survey of Intermediate-mass Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Lundquist, Michael J.; Kobulnicky, Henry A.; Kerton, Charles R.; Arvidsson, Kim

    2015-06-01

    We have conducted a 13CO survey of a sample of 128 infrared color-selected intermediate-mass star-forming region (IM SFR) candidates. We utilized the Onsala 20 m telescope to observe 13CO (1-0) toward 67 northern IM SFRs, used the 12 m Atacama Pathfinder Experiment telescope to observe 13CO (2-1) toward 22 southern IM SFRs, and incorporated an additional 39 sources from the Boston University Five College Radio Astronomy Observatory Galactic Ring Survey which observed 13CO (1-0). We detect 13CO (1-0) in 58 of the 67 northern sources and 13CO (2-1) in 20 of the 22 southern sources. The mean molecular column densities and 13CO linewidths in the inner Galaxy are higher by factors of 3.4 and 1.5, respectively, than the outer Galaxy. We attribute this difference to molecular clouds in the inner Galaxy being more massive and hosting star forming regions with higher luminosities on average than the outer Galaxy. IM SFRs have mean a molecular column density of 7.89 × 1021 cm-2, a factor of 3.1 lower than that for a sample of high-mass regions, and have a mean 13CO linewidth of 1.84 km s-1, a factor of 1.5 lower than that for high-mass regions. We demonstrate a correlation between 13CO linewidth and infrared luminosity as well as between molecular column density and infrared luminosity for the entire sample of intermediate-mass and high-mass regions. IM SFRs appear to form in distinctly lower-density environments with mean linewidths and beam-averaged column densities a factor of several lower than high-mass star-forming regions.

  12. Impact of oceanic circulation changes on atmospheric δ13CO2

    NASA Astrophysics Data System (ADS)

    Menviel, L.; Mouchet, A.; Meissner, K. J.; Joos, F.; England, M. H.

    2015-11-01

    δ13CO2 measured in Antarctic ice cores provides constraints on oceanic and terrestrial carbon cycle processes linked with millennial-scale changes in atmospheric CO2. However, the interpretation of δ13CO2 is not straightforward. Using carbon isotope-enabled versions of the LOVECLIM and Bern3D models, we perform a set of sensitivity experiments in which the formation rates of North Atlantic Deep Water (NADW), North Pacific Deep Water (NPDW), Antarctic Bottom Water (AABW), and Antarctic Intermediate Water (AAIW) are varied. We study the impact of these circulation changes on atmospheric δ13CO2 as well as on the oceanic δ13C distribution. In general, we find that the formation rates of AABW, NADW, NPDW, and AAIW are negatively correlated with changes in δ13CO2: namely, strong oceanic ventilation decreases atmospheric δ13CO2. However, since large-scale oceanic circulation reorganizations also impact nutrient utilization and the Earth's climate, the relationship between atmospheric δ13CO2 levels and ocean ventilation rate is not unequivocal. In both models atmospheric δ13CO2 is very sensitive to changes in AABW formation rates: increased AABW formation enhances the transport of low δ13C waters to the surface and decreases atmospheric δ13CO2. By contrast, the impact of NADW changes on atmospheric δ13CO2 is less robust and might be model dependent. This results from complex interplay between global climate, carbon cycle, and the formation rate of NADW, a water body characterized by relatively high δ13C.

  13. Radiative transfer of HCN: interpreting observations of hyperfine anomalies

    NASA Astrophysics Data System (ADS)

    Mullins, A. M.; Loughnane, R. M.; Redman, M. P.; Wiles, B.; Guegan, N.; Barrett, J.; Keto, E. R.

    2016-07-01

    Molecules with hyperfine splitting of their rotational line spectra are useful probes of optical depth, via the relative line strengths of their hyperfine components. The hyperfine splitting is particularly advantageous in interpreting the physical conditions of the emitting gas because with a second rotational transition, both gas density and temperature can be derived. For HCN however, the relative strengths of the hyperfine lines are anomalous. They appear in ratios which can vary significantly from source to source, and are inconsistent with local thermodynamic equilibrium (LTE). This is the HCN hyperfine anomaly, and it prevents the use of simple LTE models of HCN emission to derive reliable optical depths. In this paper, we demonstrate how to model HCN hyperfine line emission, and derive accurate line ratios, spectral line shapes and optical depths. We show that by carrying out radiative transfer calculations over each hyperfine level individually, as opposed to summing them over each rotational level, the anomalous hyperfine emission emerges naturally. To do this requires not only accurate radiative rates between hyperfine states, but also accurate collisional rates. We investigate the effects of different sets of hyperfine collisional rates, derived via the proportional method and through direct recoupling calculations. Through an extensive parameter sweep over typical low-mass star-forming conditions, we show the HCN line ratios to be highly variable to optical depth. We also reproduce an observed effect whereby the red-blue asymmetry of the hyperfine lines (an infall signature) switches sense within a single rotational transition.

  14. ALMA Observations of HCN and Its Isotopologues on Titan

    NASA Astrophysics Data System (ADS)

    Molter, Edward M.; Nixon, C. A.; Cordiner, M. A.; Serigano, J.; Irwin, P. G. J.; Teanby, N. A.; Charnley, S. B.; Lindberg, J. E.

    2016-08-01

    We present sub-millimeter spectra of HCN isotopologues on Titan, derived from publicly available ALMA flux calibration observations of Titan taken in early 2014. We report the detection of a new HCN isotopologue on Titan, H13C15N, and confirm an earlier report of detection of DCN. We model high signal-to-noise observations of HCN, H13CN, HC15N, DCN, and H13C15N to derive abundances and infer the following isotopic ratios: 12C/13C = 89.8 ± 2.8, 14N/15N = 72.3 ± 2.2, D/H = (2.5 ± 0.2) × 10‑4, and HCN/H13C15N = 5800 ± 270 (1σ errors). The carbon and nitrogen ratios are consistent with and improve on the precision of previous results, confirming a factor of ∼2.3 elevation in 14N/15N in HCN compared to N2 and a lack of fractionation in 12C/13C from the protosolar value. This is the first published measurement of D/H in a nitrile species on Titan, and we find evidence for a factor of ∼2 deuterium enrichment in hydrogen cyanide compared to methane. The isotopic ratios we derive may be used as constraints for future models to better understand the fractionation processes occurring in Titan’s atmosphere.

  15. ALMA Observations of HCN and Its Isotopologues on Titan

    NASA Astrophysics Data System (ADS)

    Molter, Edward M.; Nixon, C. A.; Cordiner, M. A.; Serigano, J.; Irwin, P. G. J.; Teanby, N. A.; Charnley, S. B.; Lindberg, J. E.

    2016-08-01

    We present sub-millimeter spectra of HCN isotopologues on Titan, derived from publicly available ALMA flux calibration observations of Titan taken in early 2014. We report the detection of a new HCN isotopologue on Titan, H13C15N, and confirm an earlier report of detection of DCN. We model high signal-to-noise observations of HCN, H13CN, HC15N, DCN, and H13C15N to derive abundances and infer the following isotopic ratios: 12C/13C = 89.8 ± 2.8, 14N/15N = 72.3 ± 2.2, D/H = (2.5 ± 0.2) × 10‑4, and HCN/H13C15N = 5800 ± 270 (1σ errors). The carbon and nitrogen ratios are consistent with and improve on the precision of previous results, confirming a factor of ˜2.3 elevation in 14N/15N in HCN compared to N2 and a lack of fractionation in 12C/13C from the protosolar value. This is the first published measurement of D/H in a nitrile species on Titan, and we find evidence for a factor of ˜2 deuterium enrichment in hydrogen cyanide compared to methane. The isotopic ratios we derive may be used as constraints for future models to better understand the fractionation processes occurring in Titan’s atmosphere.

  16. Evidence of boosted 13CO/12CO ratio in early-type galaxies in dense environments

    NASA Astrophysics Data System (ADS)

    Alatalo, Katherine; Crocker, Alison F.; Aalto, Susanne; Davis, Timothy A.; Nyland, Kristina; Bureau, Martin; Duc, Pierre-Alain; Krajnović, Davor; Young, Lisa M.

    2015-07-01

    We present observations of 13CO(1-0) in 17 Combined Array for Research in Millimeter Astronomy ATLAS3D early-type galaxies (ETGs), obtained simultaneously with 12CO(1-0) observations. The 13CO in six ETGs is sufficiently bright to create images. In these six sources, we do not detect any significant radial gradient in the 13CO/12CO ratio between the nucleus and the outlying molecular gas. Using the 12CO channel maps as 3D masks to stack the 13CO emission, we are able to detect 15/17 galaxies to >3σ (and 12/17 to at least 5σ) significance in a spatially integrated manner. Overall, ETGs show a wide distribution of 13CO/12CO ratios, but Virgo cluster and group galaxies preferentially show a 13CO/12CO ratio about two times larger than field galaxies, although this could also be due to a mass dependence, or the CO spatial extent (RCO/Re). ETGs whose gas has a morphologically settled appearance also show boosted 13CO/12CO ratios. We hypothesize that this variation could be caused by (i) the extra enrichment of gas from molecular reprocessing occurring in low-mass stars (boosting the abundance of 13C to 12C in the absence of external gas accretion), (ii) much higher pressure being exerted on the mid-plane gas (by the intracluster medium) in the cluster environment than in isolated galaxies, or (iii) all but the densest molecular gas clumps being stripped as the galaxies fall into the cluster. Further observations of 13CO in dense environments, particularly of spirals, as well as studies of other isotopologues, should be able to distinguish between these hypotheses.

  17. 13CO2 recovery fraction in expired air of septic patients under mechanical ventilation.

    PubMed

    Auxiliadora-Martins, M; Martins, M A; Coletto, F A; Martins-Filho, O A; Marchini, J S; Basile-Filho, A

    2008-07-01

    The continuous intravenous administration of isotopic bicarbonate (NaH13CO2) has been used for the determination of the retention of the 13CO2 fraction or the 13CO2 recovered in expired air. This determination is important for the calculation of substrate oxidation. The aim of the present study was to evaluate, in critically ill patients with sepsis under mechanical ventilation, the 13CO2 recovery fraction in expired air after continuous intravenous infusion of NaH13CO2 (3.8 micromol/kg diluted in 0.9% saline in ddH2O). A prospective study was conducted on 10 patients with septic shock between the second and fifth day of sepsis evolution (APACHE II, 25.9 +/- 7.4). Initially, baseline CO2 was collected and indirect calorimetry was also performed. A primer of 5 mL NaH13CO2 was administered followed by continuous infusion of 5 mL/h for 6 h. Six CO2 production (VCO2) measurements (30 min each) were made with a portable metabolic cart connected to a respirator and hourly samples of expired air were obtained using a 750-mL gas collecting bag attached to the outlet of the respirator. 13CO2 enrichment in expired air was determined with a mass spectrometer. The patients presented a mean value of VCO2 of 182 +/- 52 mL/min during the steady-state phase. The mean recovery fraction was 0.68 +/- 0.06%, which is less than that reported in the literature (0.82 +/- 0.03%). This suggests that the 13CO2 recovery fraction in septic patients following enteral feeding is incomplete, indicating retention of 13CO2 in the organism. The severity of septic shock in terms of the prognostic index APACHE II and the sepsis score was not associated with the 13CO2 recovery fraction in expired air. PMID:18719737

  18. Optimization of the HCN interferometer on J-TEXT tokamak

    NASA Astrophysics Data System (ADS)

    Shi, P.; Gao, L.; Xiong, C. Y.; Liu, Y.; Chen, J.; Zhuang, G.

    2015-12-01

    Recently, the HCN interferometer on J-TEXT has been optimized in many aspects. Firstly, the output power of laser source is more stable after using a new designed movable mirror frame and upgrading the oil thermostatic system. Secondly, the electromagnetic interferences have been eliminated by designing a shielding system. Additionally, the signal-to-noise ratio of intermediate frequency (IF) signal has been increased more than five times by improving the detector circuit. The density resolution has been increased from 1×1018 m-3 to 2×1017 m-3 and the sawtooth oscillation has also been measured by the HCN interferometer on J- TEXT after optimizations.

  19. Cannabinoid Control of Learning and Memory through HCN Channels.

    PubMed

    Maroso, Mattia; Szabo, Gergely G; Kim, Hannah K; Alexander, Allyson; Bui, Anh D; Lee, Sang-Hun; Lutz, Beat; Soltesz, Ivan

    2016-03-01

    The mechanisms underlying the effects of cannabinoids on cognitive processes are not understood. Here we show that cannabinoid type-1 receptors (CB1Rs) control hippocampal synaptic plasticity and spatial memory through the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that underlie the h-current (Ih), a key regulator of dendritic excitability. The CB1R-HCN pathway, involving c-Jun-N-terminal kinases (JNKs), nitric oxide synthase, and intracellular cGMP, exerts a tonic enhancement of Ih selectively in pyramidal cells located in the superficial portion of the CA1 pyramidal cell layer, whereas it is absent from deep-layer cells. Activation of the CB1R-HCN pathway impairs dendritic integration of excitatory inputs, long-term potentiation (LTP), and spatial memory formation. Strikingly, pharmacological inhibition of Ih or genetic deletion of HCN1 abolishes CB1R-induced deficits in LTP and memory. These results demonstrate that the CB1R-Ih pathway in the hippocampus is obligatory for the action of cannabinoids on LTP and spatial memory formation. PMID:26898775

  20. VIBRATIONALLY EXCITED HCN IN THE LUMINOUS INFRARED GALAXY NGC 4418

    SciTech Connect

    Sakamoto, Kazushi; Aalto, Susanne; Evans, Aaron S.; Wiedner, Martina C.; Wilner, David J.

    2010-12-20

    Infrared pumping and its effect on the excitation of HCN molecules can be important when using rotational lines of HCN to probe dense molecular gas in galaxy nuclei. We report the first extragalactic detection of (sub)millimeter rotational lines of vibrationally excited HCN, in the dust-enshrouded nucleus of the luminous infrared galaxy NGC 4418. We estimate the excitation temperature of T{sub vib} {approx} 230 K between the vibrational ground and excited (v{sub 2} = 1) states. This excitation is most likely due to infrared radiation. At this high vibrational temperature the path through the v{sub 2} = 1 state must have a strong impact on the rotational excitation in the vibrational ground level, although it may not be dominant for all rotational levels. Our observations also revealed nearly confusion-limited lines of CO, HCN, HCO{sup +}, H{sup 13}CN, HC{sup 15}N, CS, N{sub 2}H{sup +}, and HC{sub 3}N at {lambda} {approx} 1 mm. Their relative intensities may also be affected by the infrared pumping.

  1. HCN Polymers: Toward Structure Comprehension Using High Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bonnet, Jean-Yves; Thissen, Roland; Frisari, Ma; Vuitton, Veronique; Quirico, Eric; Le Roy, Léna; Fray, Nicolas; Cottin, Hervé; Horst, Sarah; Yelle, Roger

    A lot of solar system materials, including cometary ices and Titan aerosols, contain dark matter that can be interpreted as complex nitrogen bearing organic matter [1]. In laboratory experi-ments, HCN polymers are thus analogs of great interest. In fact they may be present in Titan atmosphere and in comet nuclei and then reprocessed as a CN distributed source [2], when ices began to sublimate and ejects from the nucleus organic matter grains [3]. The presence of HCN polymers is suggested because HCN molecule has been directly observed in 1P/Halley comet [4] and others. HCN polymers are also of prebiotic interest [5] as it can form amino acid under hydrolysis conditions. Even if they have been studied during the last decades, their chemical composition and structure are still poorly understood, and a great analytical effort has to be continued. In this way we present a high resolution mass spectrometry (HRMS) and a high resolution tandem mass spectrometry (MS/HRMS) analysis of HCN polymers. It was shown [6] that this is a suitable technique to elucidate composition and structure of the soluble part of tholins analogs of Titan's atmosphere aerosols. HCN polymers have never been studied by HRMS, thus we used a LTQ-Orbitrap XL high resolution mass spectrometer to analyse the HCN polymers. These are produced at LISA by direct polymerisation of pure liquid HCN, catalyzed by ammonia. HCN polymers have been completely dissolved in methanol and then injected in the mass spectrometer by ElectroSpray Ionization (ESI). This atmospheric pressure ionization process produces protonated or deprotonated ions, but it does not fragment molecules. Thus HRMS, allows a direct access to the stoechiometry of all the ionizable molecules present in the samples. Fragmentation analyses (MS/MS) of selected ions have also been performed. Thess analysis provide information about the different chemical fonctionnalities present in HCN poly-mers and also about their structure. Thus we are able to

  2. 13CO Survey of Northern Intermediate-Mass Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Lundquist, Michael J.; Kobulnicky, H. A.; Kerton, C. R.

    2014-01-01

    We conducted a survey of 13CO with the OSO 20-m telescope toward 68 intermediate-mass star-forming regions (IM SFRs) visible in the northern hemisphere. These regions have mostly been excluded from previous CO surveys and were selected from IRAS colors that specify cool dust and large PAH contribution. These regions are known to host stars up to, but not exceeding, about 8 solar masses. We detect 13CO in 57 of the 68 IM SFRs down to a typical RMS of ~50 mK. We present kinematic distances, minimum column densities, and minimum masses for these IM SFRs.

  3. Search for H2COH+ and H2(13)CO in dense interstellar molecular clouds

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Irvine, W. M.; McGonagle, D.

    1993-01-01

    We have searched for the 2 mm transitions of H2COH+ (2(02) - 1(01)) and H2(13)CO (2(02) - 1(01), 2(12) - 1(11), and 2(11) - 1(10)) toward the dense interstellar molecular clouds Orion A, TMC-1 and L134N using the FCRAO 14m telescope. None of the transitions have been detected except the H2(13)CO transitions toward Orion-KL. We set upper limits for the abundances of the protonated formaldehyde ion (H2COH+), which are close to the abundances expected from ion-molecule chemistry.

  4. Functional Characterization of Cnidarian HCN Channels Points to an Early Evolution of Ih

    PubMed Central

    Baker, Emma C.; Layden, Michael J.; van Rossum, Damian B.; Kamel, Bishoy; Medina, Monica; Simpson, Eboni; Jegla, Timothy

    2015-01-01

    HCN channels play a unique role in bilaterian physiology as the only hyperpolarization-gated cation channels. Their voltage-gating is regulated by cyclic nucleotides and phosphatidylinositol 4,5-bisphosphate (PIP2). Activation of HCN channels provides the depolarizing current in response to hyperpolarization that is critical for intrinsic rhythmicity in neurons and the sinoatrial node. Additionally, HCN channels regulate dendritic excitability in a wide variety of neurons. Little is known about the early functional evolution of HCN channels, but the presence of HCN sequences in basal metazoan phyla and choanoflagellates, a protozoan sister group to the metazoans, indicate that the gene family predates metazoan emergence. We functionally characterized two HCN channel orthologs from Nematostella vectensis (Cnidaria, Anthozoa) to determine which properties of HCN channels were established prior to the emergence of bilaterians. We find Nematostella HCN channels share all the major functional features of bilaterian HCNs, including reversed voltage-dependence, activation by cAMP and PIP2, and block by extracellular Cs+. Thus bilaterian-like HCN channels were already present in the common parahoxozoan ancestor of bilaterians and cnidarians, at a time when the functional diversity of voltage-gated K+ channels was rapidly expanding. NvHCN1 and NvHCN2 are expressed broadly in planulae and in both the endoderm and ectoderm of juvenile polyps. PMID:26555239

  5. Functional Characterization of Cnidarian HCN Channels Points to an Early Evolution of Ih.

    PubMed

    Baker, Emma C; Layden, Michael J; van Rossum, Damian B; Kamel, Bishoy; Medina, Monica; Simpson, Eboni; Jegla, Timothy

    2015-01-01

    HCN channels play a unique role in bilaterian physiology as the only hyperpolarization-gated cation channels. Their voltage-gating is regulated by cyclic nucleotides and phosphatidylinositol 4,5-bisphosphate (PIP2). Activation of HCN channels provides the depolarizing current in response to hyperpolarization that is critical for intrinsic rhythmicity in neurons and the sinoatrial node. Additionally, HCN channels regulate dendritic excitability in a wide variety of neurons. Little is known about the early functional evolution of HCN channels, but the presence of HCN sequences in basal metazoan phyla and choanoflagellates, a protozoan sister group to the metazoans, indicate that the gene family predates metazoan emergence. We functionally characterized two HCN channel orthologs from Nematostella vectensis (Cnidaria, Anthozoa) to determine which properties of HCN channels were established prior to the emergence of bilaterians. We find Nematostella HCN channels share all the major functional features of bilaterian HCNs, including reversed voltage-dependence, activation by cAMP and PIP2, and block by extracellular Cs+. Thus bilaterian-like HCN channels were already present in the common parahoxozoan ancestor of bilaterians and cnidarians, at a time when the functional diversity of voltage-gated K+ channels was rapidly expanding. NvHCN1 and NvHCN2 are expressed broadly in planulae and in both the endoderm and ectoderm of juvenile polyps. PMID:26555239

  6. Characteristics of HCN removal using CaO at high temperatures

    SciTech Connect

    Houzhang Tan; Xuebin Wang; Congling Wang; Tongmo Xu

    2009-03-15

    Experimental investigation on the removal of hydrogen cyanide (HCN) using calcium oxide (CaO) was carried out in a fixed bed reactor at temperature ranging from 300 to 1173 K, and the original HCN was produced during the pyrolysis of pyridine. Effects of temperature, volume space velocity, and initial HCN concentration on HCN removal were discussed. The results of temperature-programmed experiments show that temperature is the main factor affecting HCN removal. With the formation of CO, HCN starts to decrease from 473 K, and remains unchanged from 673 to 873 K. At 873 K, there is a further decrease in HCN without CO formation, and when temperature is higher than 1023 K, HCN is removed completely. In the isothermal experiments, CaCN{sub 2} was detected at 723 K, but at higher temperatures of 923 and 1123 K, there was no CaCN{sub 2} in the solid residues, and the nitrogen in the removed HCN was equal to that in the formed N{sub 2}. This indicates that at a lower temperature CaO is consumed to remove HCN, CaO + 2HCN {yields} CaCN{sub 2} + CO + H{sub 2}; but at a higher temperature, CaO acts as a catalyst for HCN removal, 2C{sub i}H{sub j} + 2HCN {yields} N{sub 2} + (j + 1 - k)H{sub 2} + 2C{sub I} + 1H{sub k}. The investigation on the removal efficiency shows that there is a critical temperature and a critical volume space velocity at which the HCN removal efficiency is able to reach up to 100%. 41 refs., 9 figs., 2 tabs.

  7. Distinct Populations of HCN Pacemaker Channels Produce Voltage-dependent and Voltage-independent Currents

    PubMed Central

    Proenza, Catherine; Yellen, Gary

    2006-01-01

    Hyperpolarization-activated HCN pacemaker channels are critical for the generation of spontaneous activity and the regulation of excitability in the heart and in many types of neurons. These channels produce both a voltage-dependent current (Ih) and a voltage-independent current (Iinst or VIC). In this study, we explored the molecular basis of the voltage-independent current. We found that for the spHCN isoform, VIC averaged ∼4% of the maximum HCN conductance that could be activated by hyperpolarization. Cyclic AMP increased the voltage-independent current in spHCN to ∼8% of maximum. In HCN2, VIC was ∼2% of the maximal current, and was little affected by cAMP. VIC in both spHCN and HCN2 was blocked rapidly both by ZD7288 (an HCN channel blocker that is thought to bind in the conduction pore) and by application of Cd2+ to channels containing an introduced cysteine in the pore (spHCN-464C or HCN2-436C). These results suggest that VIC flows through the main conduction pathway, down the central axis of the protein. We suspected that VIC simply represented a nonzero limiting open probability for HCN channels at positive voltages. Surprisingly, we found instead that the spHCN channels carrying VIC were not in rapid equilibrium with the channels carrying the voltage-dependent current, because they could be blocked independently; a single application of blocker at a depolarized potential essentially eliminated VIC with little change in Ih. Thus, VIC appears to be produced by a distinct population of HCN channels. This voltage-independent current could contribute significantly to the role of HCN channels in neurons and myocytes; VIC flowing through the channels at physiological potentials would tend to promote excitability by accelerating both depolarization and repolarization. PMID:16446506

  8. New ice core records on the glacial/interglacial change in atmospheric δ13CO2

    NASA Astrophysics Data System (ADS)

    Fischer, H.; Schmitt, J.; Schneider, R.; Elsig, J.; Lourantou, A.; Leuenberger, M.; Stocker, T. F.; Koehler, P.; Lavric, J.; Raynaud, D. P.; Chappellaz, J. A.

    2010-12-01

    The reconstruction of δ13CO2 using Antarctic ice cores promises a deeper understanding on the causes of past atmospheric CO2 changes. Previous measurements on the Taylor Dome ice core over the last 30,000 years (Smith et al., 1999) indicated marine processes to be dominating the significant δ13CO2 changes over the transition, whereas glacial δ13CO2 was only slightly depleted relative to the Holocene (Leuenberger et al., 1992; Smith et al., 1999). However, significant uncertainty and the low temporal resolution of the Taylor Dome δ13CO2 data prevented a more detailed interpretation. Recently, substantial improvements have been made in the analysis and the resolution of ice core δ13CO2 records (Elsig et al., 2009; Lourantou et al., 2010). With these and new measurements presented here, three independent δ13CO2 data sets over the last glacial/interglacial transition have now been derived from the two EPICA and the Talos Dome ice cores. Two of the methods use traditional dry extraction techniques with a reproducibility of 0.07-0.1‰. The third method uses a novel sublimation technique with a reproducibility of 0.05‰. Here we compare the data sets, their analytical setups and discuss their joint information as well as their differences. The three records provide a more detailed picture on the temporal evolution of δ13CO2 and confirm two pronounced isotope minima between 18-12,000 years BP in parallel to the two major phases of CO2 increase (Lourantou et al., 2010; Smith et al., 1999) as also reflected in marine sediments (Marchitto et al., 2007; Skinner et al., 2010). Accordingly, a release of old carbon from the deep ocean is most likely responsible for a large part of the long-term increase in atmospheric CO2 in this time interval. However, the fast CO2 jumps at a round 12,000 and 14,000 years BP may be partly of terrestrial origin (Elsig, 2009; Köhler et al., 2010b). The new sublimation data set provides also unambiguous δ13CO2 data for clathrate ice in

  9. Isotope effect in dissociative electron attachment to HCN

    SciTech Connect

    Chourou, S. T.; Orel, A. E.

    2011-03-15

    We performed nuclear dynamics calculations on HCN and DCN to study the isotope effect in dissociative electron attachment. Our previous calculations at 333 K led to a ratio {sigma}{sup (CN-/HCN)}/{sigma}{sup (CN-/DCN)} of about 13, which is significantly higher than recent experimental findings. This discrepancy is attributed to the neglect of correlation and polarization effects in the scattering calculation performed. We carried out a relaxed-self-consistent field calculation to determine the variation of the resonance parameters under these effects. We observe a shift in the positions of the shape resonance as well as a narrowing of the autoionization widths resulting in an isotope ratio of 3.2 at T=333 K; in closer agreement with the measured value.

  10. Controlled subnanosecond isomerization of HCN to CNH in solution

    SciTech Connect

    Gong Jiangbin; Ma Ao; Rice, Stuart A.

    2005-05-22

    We report a study of control of the HCN{yields}CNH isomerization in a liquid Ar solution. We show, using molecular dynamics simulations, nearly complete conversion from HCN to CNH can be achieved in solution on the subnanosecond time scale without requiring laser pulse shaping or molecular alignment. The mechanism of the isomerization reaction involves multiphoton rovibrational excitation on the ground electronic state potential energy surface coupled with rapid rovibrational relaxation in solution. The results demonstrate the important role of rotation-vibration coupling in multiphoton excitation of small molecules and constitute the first realistic computational demonstration of fast, robust, and high-yield laser field manipulation of solution-phase molecular processes.

  11. Dynamics of radiation induced isomerization for HCN-CNH

    SciTech Connect

    Na, Kyungsun; Jung, Christof; Reichl, L. E.

    2006-07-21

    We have analyzed the dynamics underlying the use of sequential radiation pulses to control the isomerization between the HCN and the CNH molecules. The appearance of avoided crossings among Floquet eigenphases as the molecule interacts with the radiation pulses is the key to understanding the isomerization dynamics, both in the adiabatic and nonadiabatic regimes. We find that small detunings of the incident pulses can have a significant effect on the outcome of the isomerization process for the model we consider.

  12. Observations of HCN associated with TX Cam and IK Tau

    NASA Astrophysics Data System (ADS)

    Marvel, K. B.

    1999-12-01

    I present observations of HCN associated with the oxygen-rich stars TX Cam and IK Tau. These observations were obtained with the Owens Valley Radio Observatory millimeter array telescope, funded in part by the National Science Foundation. The distribution of HCN near these evolved stars is generally spherical in nature although mildly asymmetric. The emission is optically thick and therefore quantitative interpretation is difficult. It is clear from the images that the HCN is centrally peaked in every channel and clearly does not exist in a shell-like distribution. The overall diameter of the emission is about 750 AU for IK Tau and 940 AU for TX Cam, assuming distances of 260 pc (Loup et al. 1993) and 280 pc (Knapp et al. 1998) respectively. How oxygen-rich stars can exhibit emission from carbon-based molecules has long challenged chemical models for these sources. Charnley et al. (1995) proposed a chemical model, which also predicted the presence of C2H and CH3OH in detectable quantities. Charnley et al. (1997) subsequently used the NRAO 12-m to show that these molecules do not exist in detectable quantities near these stars. I confirm this result using interferometric observations, which are more sensitive to compact distributions of gas.

  13. Observations of HCN and its Isotopologues on Titan using ALMA

    NASA Astrophysics Data System (ADS)

    Molter, Edward; Nixon, Conor A.; Cordiner, Martin; Charnley, Steven B.; Irwin, Patrick GJ; Serigano, Joseph; Teanby, Nicholas

    2016-01-01

    Titan's atmosphere is primarily composed of molecular nitrogen (N2, 98%) and methane (CH4, ≈2%), but also hosts a myriad of trace organic species; the simplest and most abundant of these is hydrogen cyanide (HCN). The advent of ALMA provides the opportunity to observe rotational transitions in this molecule and many of its isotopologues with unprecendented sensitivity and spatial resolution. In this study we make use of publicly available ALMA calibration observations of Titan taken between April and July 2014, each lasting around 160 seconds. We report the detection of a new HCN isotopologue on Titan, H13C15N, and determine the isotopic ratios 14N/15N, 12C/13C, and D/H using high signal-to-noise observations of HCN, H13CN, HC15N, and DCN. Isotopic ratios are known to diverge throughout the solar system in planetary atmospheres due to a variety of processes, including mass-dependent escape, photochemistry, and condensation. Therefore, accurate knowledge of isotopic ratios can provide important constraints on models of the origin and evolution of planetary atmospheres.

  14. Functional contributions of HCN channels in the primary auditory neurons of the mouse inner ear.

    PubMed

    Kim, Ye-Hyun; Holt, Jeffrey R

    2013-09-01

    The hyperpolarization-activated current, Ih, is carried by members of the Hcn channel family and contributes to resting potential and firing properties in excitable cells of various systems, including the auditory system. Ih has been identified in spiral ganglion neurons (SGNs); however, its molecular correlates and their functional contributions have not been well characterized. To investigate the molecular composition of the channels that carry Ih in SGNs, we examined Hcn mRNA harvested from spiral ganglia of neonatal and adult mice using quantitative RT-PCR. The data indicate expression of Hcn1, Hcn2, and Hcn4 subunits in SGNs, with Hcn1 being the most highly expressed at both stages. To investigate the functional contributions of HCN subunits, we used the whole-cell, tight-seal technique to record from wild-type SGNs and those deficient in Hcn1, Hcn2, or both. We found that HCN1 is the most prominent subunit contributing to Ih in SGNs. Deletion of Hcn1 resulted in reduced conductance (Gh), slower activation kinetics (τfast), and hyperpolarized half-activation (V1/2) potentials. We demonstrate that Ih contributes to SGN function with depolarized resting potentials, depolarized sag and rebound potentials, accelerated rebound spikes after hyperpolarization, and minimized jitter in spike latency for small depolarizing stimuli. Auditory brainstem responses of Hcn1-deficient mice showed longer latencies, suggesting that HCN1-mediated Ih is critical for synchronized spike timing in SGNs. Together, our data indicate that Ih contributes to SGN membrane properties and plays a role in temporal aspects of signal transmission between the cochlea and the brain, which are critical for normal auditory function. PMID:23980193

  15. HCN1 Channels Contribute to the Effects of Amnesia and Hypnosis But Not Immobility of Volatile Anesthetics

    PubMed Central

    Liu, Jin; Ke, Bowen; Wang, Xiaojia; Li, Fengshan; Li, Tao; Bayliss, Douglas A.; Chen, Xiangdong

    2015-01-01

    Background HCN1 channels have been identified as targets of ketamine to produce hypnosis. Volatile anesthetics also inhibit HCN1 channels. However, the effects of HCN1 channels on volatile anesthetics in vivo is still elusive. This study uses global and conditional HCN1 knockout mice to evaluate how HCN1 channels affect the actions of volatile anesthetics. Methods Minimum alveolar concentrations (MAC) of isoflurane and sevoflurane that induced immobility (MAC of immobility) and/or hypnosis (MAC of hypnosis) were determined in wild-type (WT) mice, global HCN1 channel knockout mice (HCN1−/−), floxed HCN1 channel gene (HCN1f/f) mice and forebrain-selective HCN1 channel knockout (HCN1f/f: cre) mice. Immobility of mice was defined as no purposeful reactions to tail-clamping stimulus and hypnosis was defined as loss of righting reflex (LORR). The amnestic effects of isoflurane and sevoflurane were evaluated by fear-potentiated startle in these four strains of mice. Results All MAC values were expressed as mean ± SEM. For MAC of immobility of isoflurane, no significant difference was found among wild-type, HCN1−/−, HCN1f/f and HCN1f/f: cre mice (all ~1.24-1.29% isoflurane). For both HCN1−/− and HCN1f/f: cre mice, the MAC of hypnosis for isoflurane (each ~1.05% isoflurane) were significantly increased over their nonknockout controls: HCN1−/− vs. wild-type (0.86±0.03%, P<0.001) and HCN1f/f: cre vs. HCN1f/f mice (0.84±0.03%, P<0.001); no significant difference was found between HCN1−/− and HCN1f/f: cre mice. For MAC of immobility of sevoflurane, no significant difference was found among wild-type, HCN1−/−, HCN1f/f and HCN1f/f: cre mice (all ~2.6-2.7% sevoflurane). For both HCN1−/− and HCN1f/f: cre mice, the MAC of hypnosis for sevoflurane (each ~1.90% sevoflurane) was significantly increased over their nonknockout controls: HCN1−/− vs. wild-type (1.58±0.05%, P<0.001) and HCN1f/f: cre vs. HCN1f/f mice (1.56±0.05%, P<0.001). No significant

  16. Structural mechanism for the regulation of HCN ion channels by the accessory protein TRIP8b

    PubMed Central

    DeBerg, Hannah A.; Bankston, John R.; Rosenbaum, Joel C.; Brzovic, Peter S.; Zagotta, William N.; Stoll, Stefan

    2015-01-01

    Summary Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels underlie the cationic Ih current present in many neurons. The direct binding of cAMP to HCN channels increases the rate and extent of channel opening and results in a depolarizing shift in the voltage dependence of activation. TRIP8b is an accessory protein that regulates the cell surface expression and dendritic localization of HCN channels and reduces the cyclic nucleotide dependence of these channels. Here we use electron paramagnetic resonance (EPR) to show that TRIP8b binds to the apo state of the cyclic nucleotide-binding domain (CNBD) of HCN2 channels without changing the overall domain structure. With EPR and nuclear magnetic resonance (NMR), we locate TRIP8b relative to the HCN channel and identify the binding interface on the CNBD. These data provide a structural framework for understanding how TRIP8b regulates the cyclic nucleotide dependence of HCN channels. PMID:25800552

  17. HCN Producing Bacteria Enable Sensing Of Non-Bioavailable Hg Species by the Whole Cell Biosensor

    NASA Astrophysics Data System (ADS)

    Horvat, M.; Rijavec, T.; Koron, N.; Lapanje, A.

    2015-12-01

    Bacteria play an important role in Hg transformation reactions. The production of cyanide (HCN) and other secondary metabolites seems to be key elements involved in these transformations. Current hypotheses link the role of HCN production to growth inhibition of nonHCN producing competitor organisms (role of an antimicrobial agent). Our past investigations showed that HCN production did not correlate with antimicrobial activity and since pK value of HCN is very high (pK = 9,21), it can be expected that most of the produced HCN is removed from the microenvironment. This way, the expected inhibitory concentrations can hardly be reached. Accordingly, we proposed a new concept, where the ability of complexation of transient metals by HCN served as a regulation process for the accessibility of micro-elements. In our study, we focused on the presence of HCN producing bacteria and carried it out in the Hg contaminated environment connected to the Idrija Mercury Mine, Slovenia. We characterised the isolates according to the presence of Hg resistance (HgR), level of HCN production and genetic similarities. In laboratory setups, using our merR whole cell based biosensor, we determined the transformation of low bioavailable Hg0 and HgS forms into bioavailable Hg by these HCN producing bacteria. We observed that HgR strains producing HCN had the highest impact on increased Hg bioavailability. In the proposed ecological strategy HgR HCN producing bacteria increase their competitive edge over non-HgR competitors through the increase of Hg toxicity. Due to their activity, Hg is made available to other organisms as well and thus enters into the ecosystem. Finally, using some of the characteristics of bacteria (e.g. Hg resistance genetic elements), we developed a fully automated sensing approach, combining biosensorics and mechatronics, to measure the bioavailability of Hg in situ.

  18. Association reactions at low pressure. 5: The CH3(+)/HCN system. A final word?

    NASA Technical Reports Server (NTRS)

    Anicich, Vincent G.; Sen, Atish D.; Huntress, Wesley, Jr.; McEwan, Murray J.

    1995-01-01

    The reaction of the methyl cation with hydrogen cyanide is revisited. We have confidence that we have resolved a long standing apparent contradiction of experimental results. A literature history is presented along with one new experiment and a re-examination of an old experiment. In this present work it is shown that all of the previous studies had made consistent observations. Yet, each of the previous studies failed to observe all of the information present. The methyl cation does react with HCN by radiative association, a fact which had been in doubt. The product ions formed in the two-body and three-body processes react differently with HCN. The collisionally stabilized association product formed by a three-body mechanism, does not react with HCN and is readily detected in the experiments. The radiatively stabilized association product, formed by a slow two-body reaction, is not detected because it reacts with HCN by a fast proton transfer reaction forming the protonated HCN ion. Previous studies either 'lost' this product in the extremely large protonated HCN signal that is always present when HCN is used, or discounted it for various reasons. We have been able to show by ion cyclotron resonance (ICR) techniques (both FT-ICR and tandem ICR-dempster-ICR) that the radiative association product does react with the HCN to form the protonated HCN ion.

  19. On The Effect of Electron Collisions in the Excitation of Cometary HCN

    NASA Technical Reports Server (NTRS)

    Lovell, Amy J.; Kallivayalil, Nitya; Schloerb, F. Peter; Combi, Michael R.; Hansen, Kenneth C.; Gombosi, T. I.

    2004-01-01

    The electron-HCN collision rate for the excitation of rotational transitions of the HCN molecule is evaluated in comets C/1995 01 (Hale-Bopp) and C/1996 B2 (Hyakutake). Based on theoretical models of the cometary atmosphere, we show that collisions with electrons can provide a significant excitation mechanism for rotational transitions in the HCN molecule. Computed values of the cross section sigma(sub e-HCN) can be as high as 1.3 x cm2, more than 2 orders of magnitude greater than the commonly assumed HCN-H2O cross section. For the ground rotational transitions of HCN, the electron-HCN collision rate is found to exceed the HCN-H2O collision rate at distances greater than 3000 km from the cometary nucleus of Hale-Bopp and 1000 km from that of Hyakutake. Collisional excitation processes dominate over radiative excitation processes up to a distance of 160,000 km from the cometary nucleus of Hale-Bopp and 50,000 km from that of Hyakutake. Excitation models that neglect electron collisions can underestimate the HCN gas production rates by as much as a factor of 2.

  20. Photochemistry of methane and the formation of hydrocyanic acid (HCN) in the earth's early atmosphere

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.

    1986-01-01

    A one-dimensional photochemical model is used to analyze the photochemistries of CH4 and HCN in the primitive terrestrial atmosphere. CH4, N2, and HCN photolysis are examined. The background atmosphere and boundary conditions applied in the analysis are described. The formation of HCN as a by-product of N2 and CH4 photolysis is investigated; the effects of photodissociation and rainfall on HCN is discussed. The low and high CH4 mixing ratios and radical densities are studied.

  1. Lidocaine Inhibits HCN Currents in Rat Spinal Substantia Gelatinosa Neurons

    PubMed Central

    Hu, Tao; Liu, Nana; Lv, Minhua; Ma, Longxian; Peng, Huizhen; Peng, Sicong

    2016-01-01

    BACKGROUND: Lidocaine, which blocks voltage-gated sodium channels, is widely used in surgical anesthesia and pain management. Recently, it has been proposed that the hyperpolarization-activated cyclic nucleotide (HCN) channel is one of the other novel targets of lidocaine. Substantia gelatinosa in the spinal dorsal horn, which plays key roles in modulating nociceptive information from primary afferents, comprises heterogeneous interneurons that can be electrophysiologically categorized by firing pattern. Our previous study demonstrated that a substantial proportion of substantia gelatinosa neurons reveal the presence of HCN current (Ih); however, the roles of lidocaine and HCN channel expression in different types of substantia gelatinosa neurons remain unclear. METHODS: By using the whole-cell patch-clamp technique, we investigated the effect of lidocaine on Ih in rat substantia gelatinosa neurons of acute dissociated spinal cord slices. RESULTS: We found that lidocaine rapidly decreased the peak Ih amplitude with an IC50 of 80 μM. The inhibition rate on Ih was not significantly different with a second application of lidocaine in the same neuron. Tetrodotoxin, a sodium channel blocker, did not affect lidocaine’s effect on Ih. In addition, lidocaine shifted the half-activation potential of Ih from −109.7 to −114.9 mV and slowed activation. Moreover, the reversal potential of Ih was shifted by −7.5 mV by lidocaine. In the current clamp, lidocaine decreased the resting membrane potential, increased membrane resistance, delayed rebound depolarization latency, and reduced the rebound spike frequency. We further found that approximately 58% of substantia gelatinosa neurons examined expressed Ih, in which most of them were tonically firing. CONCLUSIONS: Our studies demonstrate that lidocaine strongly inhibits Ih in a reversible and concentration-dependent manner in substantia gelatinosa neurons, independent of tetrodotoxin-sensitive sodium channels. Thus, our

  2. Cotton-Mouton polarimeter with HCN laser on CHS

    SciTech Connect

    Akiyama, T.; Kawahata, K.; Ito, Y.; Okajima, S.; Nakayama, K.; Okamura, S.; Matsuoka, K.; Isobe, M.; Nishimura, S.; Suzuki, C.; Yoshimura, Y.; Nagaoka, K.; Takahashi, C.

    2006-10-15

    Polarimeters based on the Cotton-Mouton effect hold promise for electron density measurements. We have designed and installed a Cotton-Mouton polarimeter on the Compact Helical System. The Cotton-Mouton effect is measured as the phase difference between probe and reference beams. In this system, an interferometric measurement can be performed simultaneously with the same probe chord. The light source is a HCN laser (wavelength of 337 {mu}m). Digital complex demodulation is adopted for small phase analysis. The line averaged density evaluated from the polarimeter along a plasma center chord is almost consistent with that from the interferometer.

  3. Laser stark spectroscopy of SO2 with the HCN laser

    NASA Technical Reports Server (NTRS)

    Sarker, J. C.; Johnston, L. H.; Bhattacharjee, R. L.; Sudhakaran, G. R.

    1991-01-01

    The far infrared laser Stark spectrum of SO2 was investigated using the 337-micron line of the HCN laser. Two distinct families, one originating at low field and the other at high field, were observed. The high field transition is identified. A significant fourth-order Stark shift was observed for this transition in the presence of a large second-order Stark shift. The zero-field frequency of the assigned transition was obtained by accounting for the fourth-order contribution.

  4. The presence of pacemaker HCN channels identifies theta rhythmic GABAergic neurons in the medial septum

    PubMed Central

    Varga, Viktor; Hangya, Balázs; Kránitz, Kinga; Ludányi, Anikó; Zemankovics, Rita; Katona, István; Shigemoto, Ryuichi; Freund, Tamás F; Borhegyi, Zsolt

    2008-01-01

    The medial septum (MS) is an indispensable component of the subcortical network which synchronizes the hippocampus at theta frequency during specific stages of information processing. GABAergic neurons exhibiting highly regular firing coupled to the hippocampal theta rhythm are thought to form the core of the MS rhythm-generating network. In recent studies the hyperpolarization-activated, cyclic nucleotide-gated non-selective cation (HCN) channel was shown to participate in theta synchronization of the medial septum. Here, we tested the hypothesis that HCN channel expression correlates with theta modulated firing behaviour of MS neurons by a combined anatomical and electrophysiological approach. HCN-expressing neurons represented a subpopulation of GABAergic cells in the MS partly overlapping with parvalbumin (PV)-containing neurons. Rhythmic firing in the theta frequency range was characteristic of all HCN-expressing neurons. In contrast, only a minority of HCN-negative cells displayed theta related activity. All HCN cells had tight phase coupling to hippocampal theta waves. As a group, PV-expressing HCN neurons had a marked bimodal phase distribution, whereas PV-immunonegative HCN neurons did not show group-level phase preference despite significant individual phase coupling. Microiontophoretic blockade of HCN channels resulted in the reduction of discharge frequency, but theta rhythmic firing was perturbed only in a few cases. Our data imply that HCN-expressing GABAergic neurons provide rhythmic drive in all phases of the hippocampal theta activity. In most MS theta cells rhythm genesis is apparently determined by interactions at the level of the network rather than by the pacemaking property of HCN channels alone. PMID:18565991

  5. Characterization of the role of HCN channels in β3-adrenoceptor mediated rat bladder relaxation

    PubMed Central

    Kashyap, Mahendra; Yoshimura, Naoki; Smith, Phillip P.; Chancellor, Michael; Tyagi, Pradeep

    2015-01-01

    Objective The second messenger cAMP is involved in both β3 adrenoceptor (β3-AR) mediated detrusor relaxation and the kinetics of Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Here we characterized the effect HCN channel activation and possible interaction with β3-AR in bladder. Materials and Methods Bladder tissues from Sprague-Dawley rats and Human organ donors were obtained for studying species-specific expression of HCN channels by real-time qPCR and Western Blot. Effect of β3-agonist on rat bladder strips (0.5 × 0.5 × 7 mm in size) was studied during activation and blockade of HCN channels by Lamotrigine and ZD7288, respectively. Results Expression of all four genes encoding for HCN channels (HCN1-4) was detected separately in bladder mucosa and detrusor from human and rat bladders. Species based differences were evident from relatively higher expression of HCN4 isoform in human bladder and that of HCN1 in rat bladder. Western blot confirmed the findings at mRNA level. Cumulative application β3-AR agonist CL316,243 produced a concentration dependent decrease in resting tension of rat bladder strips expressed as integral of mechanical activity. Pre-incubation of HCN channel blocker ZD 7288 opposed the relaxant effect of CL316,243, whereas co-administration of lamotrigine with CL316,243 at equal molar concentrations caused an additive decrease in resting tension. Cumulative addition of ZD7288 and lamotrigine in absence of CL316,243 showed opposing effects on detrusor contractility. Conclusions Species-specific differences were noted in expression of HCN channels in bladder. Opposing effects ZD7288 and Lamotrigine in the action of β3-AR agonist demonstrate possible functional interaction of HCN channels and β3-AR in detrusor contractility. PMID:26709376

  6. Haze Formation is an Important Sink for HCN on Titan

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Cuzzi, Jeffrey N. (Technical Monitor)

    1996-01-01

    Titan's organic haze is potentially an important sink of photochemically produced carbon and nitrogen compounds. An assortment of microphysical haze models all suggest that the haze production rate is 10(exp -14) gm per square centimeter per second, within a factor of two. Spectral analysis of laboratory tholins compared to Titan's geometric albedo spectrum suggest that the laboratory material is a good analog to Titan's haze. The laboratory material has an elemental composition given approximately by C4H4N, with an uncertainty in the C/N ratio of a factor of two. Thus, the haze represents a sink for C of 4 x 10(exp 8) per square centimeter per second, and a sink for N of 1 x 10(exp 8) per square centimeter per second. The C sink is small compared to condensation of hydrocarbons but the sink for N is comparable to the total production rate of HCN. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere.

  7. NMR determination of photorespiration in intact leaves using in vivo 13CO 2 labeling

    NASA Astrophysics Data System (ADS)

    Cegelski, Lynette; Schaefer, Jacob

    2006-01-01

    Solid-state 13C NMR measurements of intact soybean leaves labeled by 13CO 2 lead to the conclusion that photorespiration is 17% of photosynthesis for a well-watered and fertilized plant. This is the first direct assessment of the level of photorespiration in a functioning plant. A 13C{ 31P} rotational-echo double-resonance (REDOR) measurement tracked the incorporation of 13C label into intermediates in the Calvin cycle as a function of time. For labeling times of 5 min or less, the isotopic enrichment of the Calvin cycle depends on the flux of labeled carbon from 13CO 2, relative to the flux of unlabeled carbon from glycerate returned from the photorespiratory cycle. Comparisons of these two rates for a fixed value of the 13CO 2 concentration indicate that the ratio of the rate of photosynthesis to the rate of photorespiration of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in soybean leaves is 5.7. This translates into a photorespiratory CO 2 loss that is 21% of net CO 2 assimilation, about 80% of the value estimated from Rubisco kinetics parameters. The ratio of rates is reduced at low external CO 2 concentrations, as measured by net carbon assimilation rates. The carbon assimilation was determined from 13C-label spin counts converted into total carbon by the REDOR-determined isotopic enrichments of the Calvin cycle. The net carbon assimilation rates indicate that the rate of decarboxylation of glycine is not directly proportional to the oxygenase activity of Rubisco as is commonly assumed.

  8. Interaction of Caveolin-3 and HCN is involved in the pathogenesis of diabetic cystopathy

    PubMed Central

    Dong, Xingyou; Song, Qixiang; Zhu, Jingzhen; Zhao, Jiang; Liu, Qian; Zhang, Teng; Long, Zhou; Li, Jia; Wu, Chao; Wang, Qingqing; Hu, Xiaoyan; Damaser, Margot; Li, Longkun

    2016-01-01

    A growing body of research suggests that impaired bladder Cajal-like interstitial cells (ICCs) are a important component in the pathogenesis of diabetes-induced bladder dysfunction, although the molecular mechanisms have not been illustrated completely. The purpose of this study was to examine whether the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in ICCs-DM were responsible for the detrusor weak contractility of Diabetic cystopathy (DCP) and to study the possible mechanism of regulating the expression and function of HCN channels. HCN channels expression were decreased at the mRNA and protein levels. Forskolin (FSK), which can elevate intracellular cAMP levels, increased the density of the hyperpolarization-activated current and intracellular calcium concentration in both normal control (NC) rats and DCP rats, but the sensitivity of FSK on HCN channels was clearly down-regulated in DCP rats. The loss of caveolae and caveolin was in accordance with the decrease in HCN channels. Caveolin-3 co-localizes with and affects the expression and function of HCN. Taken together, these results indicate that the loss of caveolae and HCN channels in ICCs-DM is important in the pathogenesis of DCP. Increasing the number of caveolae to enhance the function of HCN channels may represent a viable target for the pharmacological treatment of DCP. PMID:27122250

  9. Chemical evolution. XXII - The hydantoins released on hydrolysis of HCN oligomers

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Wos, J. D.; Lobo, A. P.

    1974-01-01

    The isolation of three hydantoins from HCN oligomers is described. One of these hydantoins, 5-carboxymethylidine hydantoin (5-CMH), rearranges to pyrimidine orotic acid in basic solution. The isolation of 5-CMH suggests the possibility that pyrimidines were formed directly from HCN on the primitive earth.

  10. HCN1 Channels Enhance Rod System Responsivity in the Retina under Conditions of Light Exposure

    PubMed Central

    Sothilingam, Vithiyanjali; Michalakis, Stylianos; Garcia Garrido, Marina; Biel, Martin

    2016-01-01

    Purpose Vision originates in rods and cones at the outer retina. Already at these early stages, diverse processing schemes shape and enhance image information to permit perception over a wide range of lighting conditions. In this work, we address the role of hyperpolarization-activated and cyclic nucleotide-gated channels 1 (HCN1) in rod photoreceptors for the enhancement of rod system responsivity under conditions of light exposure. Methods To isolate HCN1 channel actions in rod system responses, we generated double mutant mice by crossbreeding Hcn1-/- mice with Cnga3-/- mice in which cones are non-functional. Retinal function in the resulting Hcn1-/- Cnga3-/- animals was followed by means of electroretinography (ERG) up to the age of four month. Retinal imaging via scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) was also performed to exclude potential morphological alterations. Results This study on Hcn1-/- Cnga3-/- mutant mice complements our previous work on HCN1 channel function in the retina. We show here in a functional rod-only setting that rod responses following bright light exposure terminate without the counteraction of HCN channels much later than normal. The resulting sustained signal elevation does saturate the retinal network due to an intensity-dependent reduction in the dynamic range. In addition, the lack of rapid adaptational feedback modulation of rod photoreceptor output via HCN1 in this double mutant limits the ability to follow repetitive (flicker) stimuli, particularly under mesopic conditions. Conclusions This work corroborates the hypothesis that, in the absence of HCN1-mediated feedback, the amplitude of rod signals remains at high levels for a prolonged period of time, leading to saturation of the retinal pathways. Our results demonstrate the importance of HCN1 channels for regular vision. PMID:26807953

  11. The RMS survey. 13CO observations of candidate massive YSOs in the northern Galactic plane

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Busfield, A. L.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Gibb, A. G.; Purcell, C. R.; Burton, M. G.; Maréchal, L. J. L.; Jiang, Z.; Wang, M.

    2008-08-01

    Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, high-resolution mid-infrared colour-selected sample of massive young stellar objects (MYSOs). We have identified 2000 MYSO candidates located within our Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of our follow-up observations is to identify other objects with similar colours such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will be used in combination with far-IR and (sub)millimetre fluxes to determine bolometric luminosities which will allow us to identify and remove nearby low-mass YSOs. In addition these molecular line observations will help in identifying evolved stars which are weak CO emitters. Methods: We have used the 15 m James Clerk Maxwell Telescope (JCMT), the 13.7 m telescope of the Purple Mountain Observatory (PMO), the 20 m Onsala telescope and the 22 m Mopra telescope to conduct molecular line observations towards 508 MYSOs candidates located in the 1st and 2nd Quadrants. These observations have been made at the J=1-0 (Mopra, Onsala and PMO) and J=2-1 (JCMT) rotational transition frequency of 13CO molecules and have a spatial resolution of 20´´-55´´, a sensitivity of T{A}* ≃ 0.1 K and a velocity resolution of 0.2 km s-1. We complement these targeted observations with 13CO spectra extracted from the Galactic Ring Survey (GRS), which have a velocity resolution of 0.21 km s-1 and sensitivity T{A}* ≃ 0.13-0.2 K, towards a further 403 RMS sources. Results: In this paper we present the results and analysis of the 13CO spectra obtained towards 911 MYSO candidates. We detect 13CO emission towards 780

  12. A TENTATIVE IDENTIFICATION OF HCN ICE ON TRITON

    SciTech Connect

    Burgdorf, M.; Cruikshank, D. P.; Dalle Ore, C. M.; Sekiguchi, T.; Nakamura, R.; Orton, G.; Quirico, E.; Schmitt, B.

    2010-08-01

    Spectra of Triton between 1.8 and 5.5 {mu}m, obtained in 2007 May and 2009 November, have been analyzed to determine the global surface composition. The spectra were acquired with the grism and the prism of the Infrared Camera on board AKARI with spectral resolutions of 135 and 22, respectively. The data from 4 to 5 {mu}m are shown in this Letter and compared to the spectra of N{sub 2}, CO, and CO{sub 2}, i.e., all the known ices on this moon that have distinct bands in this previously unexplored wavelength range. We report the detection of a 4{sigma} absorption band at 4.76 {mu}m (2101 cm{sup -1}), which we attribute tentatively to the presence of solid HCN. This is the sixth ice to be identified on Triton and an expected component of its surface because it is a precipitating photochemical product of Triton's thin N{sub 2} and CH{sub 4} atmosphere. It is also formed directly by irradiation of mixtures of N{sub 2} and CH{sub 4} ices. Here we consider only pure HCN, although it might be dissolved in N{sub 2} on the surface of Triton because of the evaporation and recondensation of N{sub 2} over its seasonal cycle. The AKARI spectrum of Triton also covers the wavelengths of the fundamental (1-0) band of {beta}-phase N{sub 2} ice (4.296 {mu}m, 2328 cm{sup -1}), which has never been detected in an astronomical body before, and whose presence is consistent with the overtone (2-0) band previously reported. Fundamental bands of CO and CO{sub 2} ices are also present.

  13. Prefrontal Cortex HCN1 Channels Enable Intrinsic Persistent Neural Firing and Executive Memory Function

    PubMed Central

    Thuault, Sébastien J.; Malleret, Gaël; Constantinople, Christine M.; Nicholls, Russell; Chen, Irene; Zhu, Judy; Panteleyev, Andrey; Vronskaya, Svetlana; Nolan, Matthew F.; Bruno, Randy

    2013-01-01

    In many cortical neurons, HCN1 channels are the major contributors to Ih, the hyperpolarization-activated current, which regulates the intrinsic properties of neurons and shapes their integration of synaptic inputs, paces rhythmic activity, and regulates synaptic plasticity. Here, we examine the physiological role of Ih in deep layer pyramidal neurons in mouse prefrontal cortex (PFC), focusing on persistent activity, a form of sustained firing thought to be important for the behavioral function of the PFC during working memory tasks. We find that HCN1 contributes to the intrinsic persistent firing that is induced by a brief depolarizing current stimulus in the presence of muscarinic agonists. Deletion of HCN1 or acute pharmacological blockade of Ih decreases the fraction of neurons capable of generating persistent firing. The reduction in persistent firing is caused by the membrane hyperpolarization that results from the deletion of HCN1 or Ih blockade, rather than a specific role of the hyperpolarization-activated current in generating persistent activity. In vivo recordings show that deletion of HCN1 has no effect on up states, periods of enhanced synaptic network activity. Parallel behavioral studies demonstrate that HCN1 contributes to the PFC-dependent resolution of proactive interference during working memory. These results thus provide genetic evidence demonstrating the importance of HCN1 to intrinsic persistent firing and the behavioral output of the PFC. The causal role of intrinsic persistent firing in PFC-mediated behavior remains an open question. PMID:23966682

  14. Verticillium dahliae alters Pseudomonas spp. populations and HCN gene expression in the rhizosphere of strawberry.

    PubMed

    DeCoste, Nadine J; Gadkar, Vijay J; Filion, Martin

    2010-11-01

    The production of hydrogen cyanide (HCN) by beneficial root-associated bacteria is an important mechanism for the biological control of plant pathogens. However, little is known about the biotic factors affecting HCN gene expression in the rhizosphere of plants. In this study, real-time reverse transcription PCR (qRT-PCR) assays were developed to investigate the effect of the plant pathogen Verticillium dahliae on hcnC (encoding for HCN biosynthesis) gene expression in Pseudomonas sp. LBUM300. Strawberry plants were inoculated with Pseudomonas sp. LBUM300 and (or) V. dahliae and grown in pots filled with nonsterilized field soil. RNA was extracted from rhizosphere soil sampled at 0, 15, 30, and 45 days following inoculation with V. dahliae and used for qRT-PCR analyses. Populations of V. dahliae and Pseudomonas sp. LBUM300 were also monitored using a culture-independent qPCR approach. hcnC expression was detected at all sampling dates. The presence of V. dahliae had a significant stimulation effect on hcnC gene expression and also increased the population of Pseudomonas sp. LBUM300. However, the V. dahliae population was not altered by the presence of Pseudomonas sp. LBUM300. To our knowledge, this study is the first to evaluate the effect of a plant pathogen on HCN gene expression in the rhizosphere soil. PMID:21076481

  15. Rotational non-LTE in HCN in the thermosphere of Titan: Implications for the radiative cooling

    NASA Astrophysics Data System (ADS)

    Rezac, L.; Kutepov, A. A.; Faure, A.; Hartogh, P.; Feofilov, A. G.

    2013-07-01

    Context. The thermal structure of Titan's thermosphere is determined by the balance between several heating and cooling processes. These processes must be accurately modeled to correctly interpret the available measurements and enhance our understanding of the formation and evolution of this atmosphere. One of the most important thermospheric cooling process for Titan is emission in the HCN rotational band. Aims: We aim to determine the validity of local thermodynamic equilibrium (LTE) for the HCN rotational distribution in the thermosphere of Titan and the impact of its breakdown on the HCN radiative cooling rate in the thermosphere. Methods: A general non-LTE radiative transfer code for rotational lines based on the accelerated lambda iteration (ALI) was used to calculate the excitation of HCN rotational levels in Titan's atmosphere. These level populations were then used to calculate the associated cooling rate. Results: We show that the common assumption in the models of Titan's thermospheric energy balance, namely the LTE distribution of rotational lines of HCN, is generally not valid above about 1100 km, or ~0.025 nbar, which will affect the derived thermospheric cooling rates. The effect of non-LTE is to reduce the cooling rate to 15% of the LTE value at around the exobase altitudes depending on the given density of HCN and collisional partners (N2, CH4, H2, and electrons). Since collision state-to-state quenching rates of HCN rotational levels are poorly known, a sensitivity analysis of our results to these rates is also presented.

  16. A Novel Trafficking-defective HCN4 Mutation is Associated with Early-Onset Atrial Fibrillation

    PubMed Central

    Zhang, Michael L.; Sinner, Moritz F.; Dolmatova, Elena V.; Tucker, Nathan R.; McLellan, Micheal; Shea, Marisa A.; Milan, David J.; Lunetta, Kathryn L.; Benjamin, Emelia J.; Ellinor, Patrick T.

    2014-01-01

    Background Atrial fibrillation (AF) is the most common arrhythmia, and a recent genome-wide association study identified HCN4 as a novel AF susceptibility locus. HCN4 encodes for the cardiac pacemaker channel and HCN4 mutations are associated with familial sinus bradycardia and AF. Objective To determine whether novel variants in the coding region of HCN4 contribute to the susceptibility for AF. Methods We sequenced the coding region of HCN4 for novel variants from 527 cases with early-onset AF from the Massachusetts General Hospital AF Study and 443 referents from the Framingham Heart Study. We used site-directed mutagenesis, cellular electrophysiology, immunocytochemistry and confocal microscopy to functionally characterize novel variants. Results We found the frequency of novel coding HCN4 variants was 2-fold greater for individuals with AF (seven variants) compared to the referents (three variants). We determined that one, (p.Pro257Ser, located in the amino-terminus adjacent to the first transmembrane spanning domain) of the seven novel HCN4 variants in our AF cases did not traffick to cell membrane while the remaining six were not functionally different from wild type. Also, the three novel variants in our referents did not alter function compared to wild type. Co-expression studies showed that the p.Pro257Ser mutant channel failed to co-localize with the wild type HCN4 channel on the cell membrane. Conclusion Our findings are consistent with HCN4 haploinsufficiency as the likely mechanism for early-onset AF in the p.Pro257Ser carrier. PMID:24607718

  17. Low-conductance HCN1 ion channels augment the frequency response of rod and cone photoreceptors.

    PubMed

    Barrow, Andrew J; Wu, Samuel M

    2009-05-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels are expressed in several tissues throughout the body, including the heart, the CNS, and the retina. HCN channels are found in many neurons in the retina, but their most established role is in generating the hyperpolarization-activated current, I(h), in photoreceptors. This current makes the light response of rod and cone photoreceptors more transient, an effect similar to that of a high-pass filter. A unique property of HCN channels is their small single-channel current, which is below the thermal noise threshold of measuring electronics. We use nonstationary fluctuation analysis (NSFA) in the intact retina to estimate the conductance of single HCN channels, revealing a conductance of approximately 650 fS in both rod and cone photoreceptors. We also analyze the properties of HCN channels in salamander rods and cones, from the biophysical to the functional level, showing that HCN1 is the predominant isoform in both cells, and demonstrate how HCN1 channels speed up the light response of both rods and cones under distinct adaptational conditions. We show that in rods and cones, HCN channels increase the natural frequency response of single cells by modifying the photocurrent input, which is limited in its frequency response by the speed of a molecular signaling cascade. In doing so, HCN channels form the first of several systems in the retina that augment the speed of the visual response, allowing an animal to perceive visual stimuli that change more quickly than the underlying photocurrent. PMID:19420251

  18. 13CO2 breath tests in non-invasive hepatological diagnosis

    PubMed Central

    Musialik, Joanna; Kasicka-Jonderko, Anna; Buschhaus, Magdalena

    2015-01-01

    In liver diagnostics, a simple, non-invasive test with high sensitivity and specificity is permanently being sought in order to assess the degree of liver damage. In addition to liver biopsy, algorithms using blood parameters or elastometry are used in clinical practice. However, these methods do not provide information about the true liver reserve, so the liver breath test seem to be a promising diagnostic tool. The basis of this test depends on the ability of particular hepatocyte enzyme systems to metabolise a tested substance labelled with a stable carbon isotope. The kinetics of 13CO2 elimination with expiratory air then permits quantitative assessment of the functional liver reserve and the degree of organ damage. In this paper the most commonly used tests, grouped according to the main metabolic pathways, are described. The usefulness of liver breath tests in specific clinical situations, both as a diagnostic and prognostic tool, is presented. PMID:25960807

  19. Ecological and Molecular Study of Soil Chemoautotrophic Microorganisms via the Sequestration of Atmospheric 13CO2

    NASA Astrophysics Data System (ADS)

    Hart, K. M.; Kelleher, B.; Allen, C.; Simpson, A.

    2009-05-01

    Soil Organic Matter (SOM) is the most complicated biomaterial on Earth and stores significantly more carbon than is currently present in the atmosphere [1]. It has been recently reported that humic material in SOM is a highly complex mixture of microbial and plant biopolymers and not a distinct chemical fraction as previously thought [2]. Furthermore, it has been reported that the microbial biomass contribution to SOM is not comprised of mainly humic materials and that in fact the contribution to SOM by soil microorganisms has been seriously underestimated [3]. Therefore, the question arises if we underestimate microbial biomass in soil do we also underestimate carbon sequestration by soil microbes? Soil microorganisms consist of a large range of diverse species with soil bacteria contributing a large proportion of the biomass content. Autotrophs are organisms that can produce organic compounds from CO2 as the sole carbon source, using either light (photoautotroph) or inorganic reactions (chemoautotroph) as the energy source. The aim of this project is to enrich chemoautotrophic soil microbes with carbon-13 (13C) sequestered as 13CO2. Once labeled, these target microbes can be differentiated from other microbes using techniques such as Stable Isotope Probing (SIP) and carbon NMR. This enrichment is facilitated via incubation in a custom built environmental chamber and the controlled introduction of 13CO2. Before introduction of 13CO2 the chambers capabilities had to be fully characterized to ensure that it was fit for purpose. Mixed cultures of soil chemoautotrophic microorganisms were propagated from different soils and data collected using the environmental chamber demonstrated that CO2 fluctuations mimicked the natural activity of actively growing chemoautotrophic cultures. Therefore using this soil slurry approach, a mixed culture of soil autotrophs will be exposed to 13CO2 prior to the harvesting of the microbial biomass. Ion chromatographic analysis of the

  20. Selective dissociation of the stronger bond in HCN using an optical centrifuge

    NASA Astrophysics Data System (ADS)

    Hasbani, R.; Ostojic, B.; Bunker, P. R.; Ivanov, M. Yu.

    2002-06-01

    Using the example of the HCN molecule, we study theoretically the possibility of selectively breaking the stronger bond in a triatomic molecule by rotationally accelerating it in an optical centrifuge using a combination of two oppositely chirped and counter-rotating strong laser fields. In our simulation the resultant field forces rotational acceleration of the HCN molecule to a point where the centrifugal force between the two heavy atoms (C and N) exceeds the strength of their (triple) bond. The effects of bending, rovibrational coupling, and the Coriolis force, which conspire to prevent the molecule from rotational dissociation into HC+N, can be efficiently counteracted by simple optimization of the frequency chirp.

  1. The puzzle of HCN in comets: Is it both a product and a primary species?

    NASA Astrophysics Data System (ADS)

    Mumma, M.; Bonev, B.; Charnley, S.; Cordiner, M.; DiSanti, M.; Gibb, E.; Magee-Sauer, K.; Paganini, L.; Villanueva, G.

    2014-07-01

    Hydrogen cyanide has long been regarded as a primary volatile in comets, stemming from its presence in dense molecular-cloud cores and its supposed storage in the cometary nucleus. Here, we examine the observational evidence for and against that hypothesis, and argue that HCN may also result from near-nucleus chemical reactions in the coma. The distinction (product vs. primary species) is important for multiple reasons: - HCN is often used as a proxy for water when the dominant species (H_2O) is not available for simultaneous measurement, as at radio wavelengths. If much HCN is sometimes produced in the coma, its adoption as a water proxy could introduce unwanted bias to taxonomies based on composition. - HCN is one of the few volatile carriers of nitrogen accessible to remote sensing, with NH_3 being the dominant nitrile. If HCN is mainly a product species, its precursor becomes the more important metric for compiling a taxonomic classification based on nitrogen chemistry. - The stereoisomer HNC is regarded as a product species, thought to result from coma chemistry involving HCN. But, could another reaction of a primary precursor (X-CN) with a hydrocarbon co-produce both HNC and HCN? - The production rate for CN greatly exceeds the possible production from HCN in some comets, demonstrating the presence of another (more important) precursor of CN radicals in them. - The production rates of HCN measured through rotational (radio) and vibrational (infrared) spectroscopy agree in some comets, but in others the infrared rate exceeds the radio rate substantially. Is prompt emission from vibrationally excited HCN responsible? - With its strong dipole moment and H-bonding character, HCN should be linked more strongly in the nuclear ice to other molecules with similar properties (H_2O, CH_3OH), but instead its spatial release in some comets seems strongly coupled to volatiles that lack a dipole moment and thus do not form H-bonds (methane, ethane). We will present the

  2. The Puzzle of HCN in Comets: Is it both a Product and a Primary Species?

    NASA Astrophysics Data System (ADS)

    Mumma, Michael J.; Bonev, Boncho P.; Charnley, Steven B.; Cordiner, Martin A.; DiSanti, Michael A.; Gibb, Erika L.; Magee-Sauer, Karen; Paganini, Lucas; Villanueva, Geronimo L.

    2014-11-01

    Hydrogen cyanide has long been regarded as a primary volatile in comets, stemming from its presence in dense molecular cloud cores and its supposed storage in the cometary nucleus. Here, we examine the observational evidence for and against that hypothesis, and argue that HCN may also result from near-nucleus chemical reactions in the coma. The distinction (product vs. primary species) is important for multiple reasons: 1. HCN is often used as a proxy for water when the dominant species (H2O) is not available for simultaneous measurement, as at radio wavelengths. 2. HCN is one of the few volatile carriers of nitrogen accessible to remote sensing. If HCN is mainly a product species, its precursor becomes the more important metric for compiling a taxonomic classification based on nitrogen chemistry. 3. The stereoisomer HNC is now confirmed as a product species. Could reaction of a primary precursor (X-CN) with a hydrocarbon co-produce both HNC and HCN? 4. The production rate for CN greatly exceeds that of HCN in some comets, demonstrating the presence of another (more important) precursor of CN. Several puzzling lines of evidence raise issues about the origin of HCN: a. The production rates of HCN measured through rotational (radio) and vibrational (infrared) spectroscopy agree in some comets - in others the infrared rate exceeds the radio rate substantially. b. With its strong dipole moment and H-bonding character, HCN should be linked more strongly in the nuclear ice to other molecules with similar properties (H2O, CH3OH), but instead its spatial release in some comets seems strongly coupled to volatiles that lack a dipole moment and thus do not form H-bonds (methane, ethane). c. The nucleus-centered rotational temperatures measured for H2O and other species (C2H6, CH3OH) usually agree within error, but those for HCN are often slightly smaller. d. In comet ISON, ALMA maps of HCN and the dust continuum show a slight displacement 80 km) in the centroids. We will

  3. Clay-mediated reactions of HCN oligomers - The effect of the oxidation state of the clay

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Alwis, K. W.; Edelson, E. H.; Mount, N.; Hagan, W. J., Jr.

    1981-01-01

    Montmorillonite clays which contain Fe(III) inhibit the oligomerization of aqueous solutions of HCN. The inhibitory effect is due to the rapid oxidation of diaminomaleonitrile, a key intermediate in HCN oligomerization, by the Fe(III) incorporated into the aluminosilicate lattice of the clay. The Fe(III) oxidizes diaminomaleonitrile to diiminosuccinonitrile, a compound which is rapidly hydrolyzed to HCN and oxalic acid derivatives. Diaminomaleonitrile is not oxidized when Fe(III) in the montmorillonite is reduced with hydrazine. The oxidation state of the clay is an important variable in experiments designed to simulate clay catalysis on the primitive earth.

  4. HCN - A plausible source of purines, pyrimidines and amino acids on the primitive earth

    NASA Technical Reports Server (NTRS)

    Ferris, J.-P.; Joshi, P. C.; Edelson, E. H.; Lawless, J. G.

    1978-01-01

    Dilute (0.1 M) solutions of HCN condense to oligomers at pH 9.2, and hydrolysis of these oligomers yields 4,5-dihydroxypyrimidine, orotic acid, 5-hydroxyuracil, adenine, 4-aminoimidazole-5-carboxamide, and amino acids. It is suggested that the three main classes of nitrogen-containing biomolecules - purines, pyrimidines, and amino acids may have originated from HCN on the primitive earth. It is also suggested that the presence of orotic acid and 4-aminoimidazole-5-carboxamide might indicate that contemporary biosynthetic pathways for nucleotides evolved from the compounds released on hydrolysis of HCN oligomers.

  5. A mapping study of massive cores with 13CO J = 1 0 line

    NASA Astrophysics Data System (ADS)

    Esimbek, Jarken; Wu, Yuefang; Wang, Yang

    2008-04-01

    Using 13.7 m telescope of Qinghai station of Purple Mountain Observatory (PMO) at Delingha, 27 sources were observed with 12CO J = 1-0 and mapped with 13CO J = 1-0 lines. Midcourse Space Experiment (MSX) images and IRAS point source catalogue (PSC) were used to identify stellar objects embedded in the detected cores. Forty-one 13CO cores were obtained. The sizes of these cores is from 0.4 pc to 7 pc. Their average excitation temperatures and masses are 23.4 K and 3.1 × 10 4M⊙, which shows that these cores are massive and relatively cold. The line widths are much wider than those of low-mass cores. The correlation between line widths and core sizes is weak. According to the radio, IRAS and MSX data, there are three kinds of cores in the entire sample: group A has 21 cores whose Tex and Δ V are 15.5 K and 3.2 km/s on the average. The cores in group A are not associated with infrared sources. Group B contains 17 cores, of which five are associated with IRAS sources, the remaining 12 are associated with MSX sources. All the 17 cores are not associated with UC HII regions. Group C contains three cores which are associated with UC HII regions. All these physical parameters indicate that there could be an evolutionary development from group A to group C. The bolometric luminosities of groups B and C are also investigated. The reason for the displacement of the cores and the infrared sources in group A was discussed.

  6. Kinetics of some reactions of HCN at high temperatures. Progress report, October 1, 1982-September 30, 1983

    SciTech Connect

    Hanson, R.K.; Bowman, C.T.

    1983-01-01

    The work was divided into two phases: Phase I, now completed, involved studies in shock-heated HCN/Ar and C/sub 2/N/sub 2//H/sub 2//Ar mixtures to determine rate coefficients for the thermal decompostion reactions HCN + M ..-->.. H + CN + M, H/sub 2/ + CN ..-->.. H + HCN, CN + HCN ..-->.. H + C/sub 2/N/sub 2/, and C/sub 2/N/sub 2/ + M ..-->.. 2CN + M. Phase II entails shock tube studies in various HCN/N/sub 2/O/Ar and C/sub 2/N/sub 2//H/sub 2/O/Ar mixtures to determine rate coefficients for major oxidation reactions including O + HCN ..-->.. NCO + H, (6) O + HCN ..-->.. CN + OH, (7) O + HCN ..-->.. NH + CO, OH + HCN ..-->.. Products, and OH + HCN ..-->.. CN + H/sub 2/O, with the last reaction to be studied in both the forward and reverse directions. Preliminary results show that reaction (7) plays a substantially greater role, and reaction (6) a lesser role, than previously believed in the O-atom oxidation of HCN.

  7. HCN4 mutation as a molecular explanation on patients with bradycardia and non-compaction cardiomyopathy.

    PubMed

    Millat, Gilles; Janin, Alexandre; de Tauriac, Olivier; Roux, Antoine; Dauphin, Claire

    2015-09-01

    A very recent study suggested that HCN4 mutations could be associated with sinusal bradycardia and myocardial non compaction. A French family with 3 affected sisters presenting the same clinical phenotype (sinus bradycardia in combination with non compaction cardiomyopathy (NCCM)) have benefited both from a systematic cardiovascular exploration and molecular investigations. The molecular analysis, performed by NGS sequencing, led to identify only one likely-disease causing variation: p.Gly482Arg on HCN4 gene. Our results confirm the genetic evidence for the involvement of the HCN4 mutations in the combined bradycardia-NCCM phenotype and illustrates that, in front of this combined clinical phenotype, HCN4 mutations has to be suspected. PMID:26206080

  8. Discovery and Observations of the Unusually Luminous Type-Defying II-P/II-L Supernova ASASSN-13co

    NASA Astrophysics Data System (ADS)

    Holoien, T. W.-S.; Prieto, J. L.; Pejcha, O.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Grupe, D.; Morrell, N.; Thorstensen, J. R.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Davis, A. B.; Pojmański, G.; Skowron, D. M.

    2016-06-01

    We present photometric and spectroscopic observations of ASASSN-13co, an unusually luminous Type II supernova and the first core-collapse supernova discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). First detection of the supernova was on UT 2013 August 29 and the data presented span roughly 3.5 months after discovery. We use the recently developed model by Pejcha and Prieto to model the multi-band light curves of ASASSN-13co and derive the bolometric luminosity curve. We compare ASASSN-13co to other Type II supernovae to show that it was unusually luminous for a Type II supernova and that it exhibited an atypical light curve shape that does not cleanly match that of either a standard Type II-L or Type II-P supernova.

  9. Chemistry of HCN removal from coke-oven gas using ethylenethiourea

    SciTech Connect

    Markhovskii, L.F.; Brodovich, A.I.; Proicheva, A.G.; Shmyreva, N.N.

    1983-01-01

    An ethylenediamine (EDA) process developed for the purification of coke-oven gas of acid components is a cyclic process. The process can recover H/sub 2/S and HCN simultaneously. Laboratory and pilot plant data on the removal of HCN from coke-oven gas using this process and on the processing of the spent scrubber liquor are presented. Ethylenethiourea is recoverable from the spent liquor.

  10. Control of heart rate by cAMP sensitivity of HCN channels

    PubMed Central

    Alig, Jacqueline; Marger, Laurine; Mesirca, Pietro; Ehmke, Heimo; Mangoni, Matteo E.; Isbrandt, Dirk

    2009-01-01

    “Pacemaker” f-channels mediating the hyperpolarization-activated nonselective cation current If are directly regulated by cAMP. Accordingly, the activity of f-channels increases when cellular cAMP levels are elevated (e.g., during sympathetic stimulation) and decreases when they are reduced (e.g., during vagal stimulation). Although these biophysical properties seem to make f-channels ideal molecular targets for heart rate regulation by the autonomic nervous system, the exact contribution of the major If-mediating cardiac isoforms HCN2 and HCN4 to sinoatrial node (SAN) function remains highly controversial. To directly investigate the role of cAMP-dependent regulation of hyperpolarization activated cyclic nucleotide activated (HCN) channels in SAN activity, we generated mice with heart-specific and inducible expression of a human HCN4 mutation (573X) that abolishes the cAMP-dependent regulation of HCN channels. We found that hHCN4–573X expression causes elimination of the cAMP sensitivity of If and decreases the maximum firing rates of SAN pacemaker cells. In conscious mice, hHCN4–573X expression leads to a marked reduction in heart rate at rest and during exercise. Despite the complete loss of cAMP sensitivity of If, the relative extent of SAN cell frequency and heart rate regulation are preserved. Our data demonstrate that cAMP-mediated regulation of If determines basal and maximal heart rates but does not play an indispensable role in heart rate adaptation during physical activity. Our data also reveal the pathophysiologic mechanism of hHCN4–573X–linked SAN dysfunction in humans. PMID:19570998

  11. VizieR Online Data Catalog: Arp 220 HCN and HCO+ data cubes (Martin+,

    NASA Astrophysics Data System (ADS)

    Martin, S.; Aalto, S.; Sakamoto, K.; Gonzalez-Alfonso, E.; Muller, S.; Henkel, C.; Garcia-Burillo, S.; Aladro, R.; Costagliola, F.; Harada, N.; Krips, M.; Martin-Pintado, J.; Muhle, S.; van der Werf, P.; Viti, S.

    2016-03-01

    The observations were carried out with ALMA in its Cycle 1 as part of a spectral line survey of Arp 220 (Martin et al., in preparation). In this paper we report the measurements covering HCN and HCO+ in their J=3-2 (261.152GHz and 262.794GHz) and J=4-3 (348.194GHz and 350.383GHz) transitions, as well as the corresponding v2=1 transitions of HCN. (2 data files).

  12. Hyperfine anomalies of HCN in cold dark clouds

    SciTech Connect

    Walmsley, C.M.; Churchwell, E.; Nash, A.; Fitzpatrick, E.

    1982-07-15

    We report observations of the J = 1..-->..0 line of HCN measured toward six positions in nearby low-temperature dark clouds. The measured relative intensities of the hyperfine components of the J = 1..-->..0 line are anomalous in that the F = 0..-->..1 transition is stronger than would be expected if all three components (F = 2..-->..1, F = 1..-->..1, F = 0..-->..1) had equal excitation temperatures. Differences of approximately 20% in the populations per sublevel of J = 1 could account for the observations. The results are in contrast to the situation observed in warmer molecular clouds associated with H II regions where the F = 1..-->..1 line is anomalously weak. The apparent overpopulation of J = 1, F = 0 in dark clouds may be related to the phenomenon observed in the J = 1..-->..0 transitions of HCO/sup +/ and HNC in the same objects where /sup 13/C substituted version of these species is found to be stronger than the /sup 12/C species.

  13. The RMS survey. 13CO observations of candidate massive YSOs in the southern Galactic plane

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Busfield, A. L.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Gibb, A. G.; Purcell, C. R.; Burton, M. G.; Marechal, L. J. L.

    2007-11-01

    Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, well-selected sample of massive young stellar objects (MYSOs). We have identified 2000 MYSOs candidates located within our Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of our follow-up observations is to identify other contaminating objects such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will be used in combination with far-IR and (sub)millimetre fluxes to determine bolometric luminosities which will allow us to identify and remove nearby low-mass YSOs. In addition these molecular line observations will help in identifying evolved stars which are weak CO emitters. Methods: We have used the 22 m Mopra telescope, the 15 m JCMT and the 20 m Onsala telescope to conduct molecular line observations towards 854 MYSOs candidates located in the 3rd and 4th quadrants. These observations have been made at the J = 1-0 (Mopra and Onsala) and J = 2-1 (JCMT) rotational transition frequency of 13CO molecules and have a spatial resolution of 20´´-40´´, a sensitivity of T{A}* ≃ 0.1 K and a velocity resolution of 0.2 km s-1. Results: We detect 13CO emission towards a total of 752 of the 854 RMS sources observed ( 88%). In total 2132 emission components are detected above 3σ level (typically T^*{A} ≥ 0.3 K). Multiple emission profiles are observed towards the majority of these sources - 461 sources ( 60%) - with an average of 4 molecular clouds detected along the line of sight. These multiple emission features make it difficult to assign a kinematic velocity to many of our sample. We have used archival CS (J = 2-1) and maser

  14. De novo mutations in HCN1 cause early infantile epileptic encephalopathy.

    PubMed

    Nava, Caroline; Dalle, Carine; Rastetter, Agnès; Striano, Pasquale; de Kovel, Carolien G F; Nabbout, Rima; Cancès, Claude; Ville, Dorothée; Brilstra, Eva H; Gobbi, Giuseppe; Raffo, Emmanuel; Bouteiller, Delphine; Marie, Yannick; Trouillard, Oriane; Robbiano, Angela; Keren, Boris; Agher, Dahbia; Roze, Emmanuel; Lesage, Suzanne; Nicolas, Aude; Brice, Alexis; Baulac, Michel; Vogt, Cornelia; El Hajj, Nady; Schneider, Eberhard; Suls, Arvid; Weckhuysen, Sarah; Gormley, Padhraig; Lehesjoki, Anna-Elina; De Jonghe, Peter; Helbig, Ingo; Baulac, Stéphanie; Zara, Federico; Koeleman, Bobby P C; Haaf, Thomas; LeGuern, Eric; Depienne, Christel

    2014-06-01

    Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels contribute to cationic Ih current in neurons and regulate the excitability of neuronal networks. Studies in rat models have shown that the Hcn1 gene has a key role in epilepsy, but clinical evidence implicating HCN1 mutations in human epilepsy is lacking. We carried out exome sequencing for parent-offspring trios with fever-sensitive, intractable epileptic encephalopathy, leading to the discovery of two de novo missense HCN1 mutations. Screening of follow-up cohorts comprising 157 cases in total identified 4 additional amino acid substitutions. Patch-clamp recordings of Ih currents in cells expressing wild-type or mutant human HCN1 channels showed that the mutations had striking but divergent effects on homomeric channels. Individuals with mutations had clinical features resembling those of Dravet syndrome with progression toward atypical absences, intellectual disability and autistic traits. These findings provide clear evidence that de novo HCN1 point mutations cause a recognizable early-onset epileptic encephalopathy in humans. PMID:24747641

  15. Hydrogenation of solid hydrogen cyanide HCN and methanimine CH2NH at low temperature

    NASA Astrophysics Data System (ADS)

    Theule, P.; Borget, F.; Mispelaer, F.; Danger, G.; Duvernay, F.; Guillemin, J. C.; Chiavassa, T.

    2011-10-01

    Context. Hydrogenation reactions dominate grain surface chemistry in dense molecular clouds and lead to the formation of complex saturated molecules in the interstellar medium. Aims: We investigate in the laboratory the hydrogenation reaction network of hydrogen cyanide HCN. Methods: Pure hydrogen cyanide HCN and methanimine CH2NH ices are bombarded at room temperature by H-atoms in an ultra-high vacuum experiment. Warm H-atoms are generated in an H2 plasma source. The ices are monitored with Fourier-transform infrared spectroscopy in reflection absorption mode. The hydrogenation products are detected in the gas phase by mass spectroscopy during temperature-programmed desorption experiments. Results: HCN hydrogenation leads to the formation of methylamine CH3NH2, and CH2NH hydrogenation leads to the formation of methylamine CH3NH2, suggesting that CH2NH can be a hydrogenation-intermediate species between HCN and CH3NH2. Conclusions: In cold environments the HCN hydrogenation reaction can produce CH3NH2, which is known to be a glycine precursor, and to destroy solid-state HCN, preventing its observation in molecular clouds ices.

  16. HCN observations of comets C/2013 R1 (Lovejoy) and C/2014 Q2 (Lovejoy)

    NASA Astrophysics Data System (ADS)

    Wirström, E. S.; Lerner, M. S.; Källström, P.; Levinsson, A.; Olivefors, A.; Tegehall, E.

    2016-04-01

    HCN J = 1-0 emission from the long-period comet C/2013 R1 (Lovejoy) was observed from the Onsala Space Observatory on multiple occasions during the month before its perihelion passage on December 22, 2013. We report detections for seven different dates, spanning heliocentric distances (Rh) decreasing from 0.94 to 0.82 au. Estimated HCN production rates are generally higher than previously reported for the same time period, but the implied increase in production rate with heliocentric distance, QHCN ∝ Rh-3.2, represent well the overall documented increase since it was first observed at Rh = 1.35. The implied mean HCN abundance relative to water in R1 Lovejoy is 0.2%. We also report on a detection of HCN with the new 3 mm receiver system at Onsala Space Observatory in comet C/2014 Q2 (Lovejoy) on January 14, 2015, when its heliocentric distance was 1.3 au. Relative to comet C/2013 R1 (Lovejoy), the HCN production rate of C/2014 Q2 (Lovejoy) was more than 5 times higher at similar heliocentric distances, and the implied HCN abundance relative to water 0.09%.

  17. Ectopic automaticity induced in ventricular myocytes by transgenic overexpression of HCN2.

    PubMed

    Oshita, Kensuke; Itoh, Masayuki; Hirashima, Shingo; Kuwabara, Yoshihiro; Ishihara, Keiko; Kuwahara, Koichiro; Nakao, Kazuwa; Kimura, Takeshi; Nakamura, Kei-Ichiro; Ushijima, Kazuo; Takano, Makoto

    2015-03-01

    Hyperpolarization-activated cyclic nucleotide-gated channels (HCNs) are expressed in the ventricles of fetal hearts but are normally down-regulated as development progresses. In the hypertrophied heart, however, these channels are re-expressed and generate a hyperpolarization-activated, nonselective cation current (Ih), which evidence suggests may increase susceptibility to arrhythmia. To test this hypothesis, we generated and analyzed transgenic mice overexpressing HCN2 specifically in their hearts (HCN2-Tg). Under physiological conditions, HCN2-Tg mice exhibited no discernible abnormalities. After the application of isoproterenol (ISO), however, ECG recordings from HCN2-Tg mice showed intermittent atrioventricular dissociation followed by idioventricular rhythm. Consistent with this observation, 0.3 μmol/L ISO-induced spontaneous action potentials (SAPs) in 76% of HCN2-Tg ventricular myocytes. In the remaining 24%, ISO significantly depolarized the resting membrane potential (RMP), and the late repolarization phase of evoked action potentials (APs) was significantly longer than in WT myocytes. Analysis of membrane currents revealed that these differences are attributable to the Ih tail current. These findings suggest HCN2 channel activity reduces the repolarization reserve of the ventricular action potential and increases ectopic automaticity under pathological conditions such as excessive β-adrenergic stimulation. PMID:25562801

  18. Warm HCN in the Planet Formation Zone of GV Tau N

    NASA Astrophysics Data System (ADS)

    Fuente, Asunción; Cernicharo, José; Agúndez, Marcelino

    2012-07-01

    The Plateau de Bure Interferometer has been used to map the continuum emission at 3.4 mm and 1.1 mm together with the J = 1→0 and J = 3→2 lines of HCN and HCO+ toward the binary star GV Tau. The 3.4 mm observations did not resolve the binary components, and the HCN J = 1→0 and HCO+ J = 1→0 line emissions trace the circumbinary disk and the flattened envelope. However, the 1.1 mm observations resolved the individual disks of GV Tau N and GV Tau S and allowed us to study their chemistry. We detected the HCN 3→2 line only toward the individual disk of GV Tau N, and the emission of the HCO+ 3→2 line toward GV Tau S. Simple calculations indicate that the 3→2 line of HCN is formed in the inner R < 12 AU of the disk around GV Tau N where the HCN/HCO+ abundance ratio is >300. On the contrary, this ratio is <1.6 in the disk around GV Tau S. The high HCN abundance measured in GV Tau N is well explained by photochemical processes in the warm (>400 K) and dense (n > 107 cm-3) disk surface. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

  19. Effects of Yiqi Tongyang on HCN4 Protein Phosphorylation in Damaged Rabbit Sinoatrial Node Cells

    PubMed Central

    Liu, Jinfeng; Liu, Ruxiu; Peng, Jie; Wang, Yanli

    2016-01-01

    The hyperpolarization-activated cyclic nucleotide-gated cation channel (If) is closely associated with sinoatrial node pacing function. The present study aimed to investigate the molecular mechanisms involved in pacing function improvements of damaged sinoatrial node cells and the consequent treatment effects on sick sinus syndrome (SSS) after the use of Yiqi Tongyang. HCN4 channel protein expression and phosphorylation were measured by immunoblotting and fluorescent quantitation. After ischemia-reperfusion injury (model group), the HCN4 protein and the optical density (OD) of the phosphorylated HCN4 protein as well as intracellular PKA activity in the sinoatrial node cells decreased significantly. However, the OD values and PKA activity increased to different degrees after treatment with serum containing different doses of Yiqi Tongyang; in contrast, no significant improvement was seen in the control group compared to the model group. These findings demonstrated that the use of the traditional Chinese medicine Yiqi Tongyang could increase HCN4 protein expression and phosphorylation as well as PKA activity within sinoatrial node cells damaged by ischemia-reperfusion. The HCN4 protein is involved in the If-related ion channel. Here, we speculated that these effects could be associated with upregulation of HCN4 protein phosphorylation, which consequently improved cell automaticity, increased heart rate, and had treatment effects on SSS. PMID:27069490

  20. WARM HCN IN THE PLANET FORMATION ZONE OF GV TAU N

    SciTech Connect

    Fuente, Asuncion; Cernicharo, Jose; Agundez, Marcelino

    2012-07-20

    The Plateau de Bure Interferometer has been used to map the continuum emission at 3.4 mm and 1.1 mm together with the J = 1{yields}0 and J = 3{yields}2 lines of HCN and HCO{sup +} toward the binary star GV Tau. The 3.4 mm observations did not resolve the binary components, and the HCN J = 1{yields}0 and HCO{sup +} J 1{yields}0 line emissions trace the circumbinary disk and the flattened envelope. However, the 1.1 mm observations resolved the individual disks of GV Tau N and GV Tau S and allowed us to study their chemistry. We detected the HCN 3{yields}2 line only toward the individual disk of GV Tau N, and the emission of the HCO{sup +} 3{yields}2 line toward GV Tau S. Simple calculations indicate that the 3{yields}2 line of HCN is formed in the inner R < 12 AU of the disk around GV Tau N where the HCN/HCO{sup +} abundance ratio is >300. On the contrary, this ratio is <1.6 in the disk around GV Tau S. The high HCN abundance measured in GV Tau N is well explained by photochemical processes in the warm (>400 K) and dense (n > 10{sup 7} cm{sup -3}) disk surface.

  1. Tracing photosynthetic carbon in leaves with nanoSIMS after 13CO2 labelling

    NASA Astrophysics Data System (ADS)

    Dannoura, Masako; Takeuchi, Miyuki; Kominami, Yuji; Takanashi, Satoru; Kenichi, Yoshimura; Ataka, Mioko

    2015-04-01

    To understand the carbon allocation of the tree and forest ecosystem, it is important to consider the residence time of carbon in different pools at suitable time scales. For example the carbon used for respiration will stay a few minutes to a few days in the tree, the carbon used for storage or structure of leaves will stay months to years, and the carbon used for wood structure, it will stay over the whole lifespan of the tree. The leaves are the entrance of carbon in trees where it can be used for foliage growth and maintenance or exported to the other organs or the other forest ecosystem compartments. Tracing carbon isotope using NanoSIMS technique is one of useful methods to estimate where and how long the carbon stay in the tree organs. In this study, 13CO2 pulse labelling were conducted and 13C was measured by IRMS to see the amount of C remaining in the leaves with time.NanoSIMS was used to localize where the labelled C remained within the leaf tissue. Twice labelling were done on branches of Quercus serrata at FFPRI(Forest and Forest Products research Institute) in Kyoto, Japan. The first labelling was in 30 April 2012 when the leaves start flushing and the second one was in 29 May 2012 when the leaves were completely deployed. For both labelling experiment, one branch was selected and covered with transparent plastic bag. CO2 concentration was recorded with IRGA and air temperature inside the chamber was monitored. Then 13CO2 was injected into the bag, and after 1 hour, the bag was removed and the branch was again exposed to ambient air. Leaves were collected before and 10-12 times after labelling and their isotope compositions were measured by IRMS. The leaf collected just after labelling and 6 days after labelling were used for NanoSIMS observation. Samples for nanoSIMS were preserved in glutaraldehyde and then embed in epoxy resin. The sliced sample were placed on the silicon wafer and observed by NanoSIMS 50L(Cameca, France). The 13C was highest just

  2. Bima Array Detections of HCN in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)

    NASA Technical Reports Server (NTRS)

    Friedel, D. N.; Remijan, A.; Snyder, L. E.; AHearn, M. F.; Blake, Geoffrey A.; dePater, Imke; Dickel, H. R.; Forster, J. R.; Hogerheijde, M. R.

    2004-01-01

    We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) Array in its D-configuration cross-correlation mode. We detected the HCN J = 1 - 0 emission line in both comets. With a 25".4 x 20".3 synthesized beam around Comet LINEAR, we found a total beam averaged HCN column density (assuming a rotation temperature of 146 K) of < N(sub T) > = 2.1(11)x 10(sup 13) cm(exp -2), and a HCN production rate of Q(HCN)=2.8(15)x 10(sup 27) s(exp -1). With a 21".3 x 17".5 synthesized beam around Comet NEAT, we found a total beam averaged HCN column density (assuming a rotation temperature of 107 K) of < N(sub T) > = 5.7(30) x 10(sup l2) cm(exp -2), and a HCN production rate of Q(HCN)=8.3(44) x 10(sup 26) s(exp -l) giving a production rate of HCN relative to H2O of approximately 0.09(5)%. The production rates relative to H2O and spatial extent of HCN are similar to previous comet observations.

  3. High-resolution spectroscopy of the {A}^{1}{\\rm{\\Pi }}(v^{\\prime} =0{--}10){--}{X}^{1}{{\\rm{\\Sigma }}}^{+}(v^{\\prime\\prime} =0) bands in 13C18O: term values, ro-vibrational oscillator strengths and Hönl–London corrections

    NASA Astrophysics Data System (ADS)

    Lemaire, J. L.; Eidelsberg, M.; Heays, A. N.; Gavilan, L.; Federman, S. R.; Stark, G.; Lyons, J. R.; de Oliveira, N.; Joyeux, D.

    2016-08-01

    Our knowledge of astronomical environments containing CO depends on accurate molecular data to reproduce and interpret observations. The constant improvement in UV space instrumentation, both in sensitivity and resolution, requires increasingly detailed laboratory data. Following a long-term experimental campaign at the SOLEIL Synchrotron facility, we have acquired complete datasets on the CO isotopologues in the vacuum ultraviolet. Absorption spectra were recorded using the Fourier-transform spectrometer installed on the DESIRS beamline, providing a resolving power R > 106 in the 8–12 eV range. Such resolution allows the analysis of individual line positions and strengths in electronic transitions and the location of perturbations. We continue our previous work on A–X bands of 12C16O and 13C16O, reporting here measurements for the 13C18O isotopologue. Gas column densities in the differentially-pumped system were calibrated using the B {}1{{{Σ }}}+–X {}1{{{Σ }}}+({v}\\prime =0,v\\prime\\prime =0) band. Absorption bands are analyzed by synthesizing line and band profiles and fitting them to measured spectra. New results for A {}1{{\\Pi }}({v}\\prime =0{--}10)–X {}1{{{Σ }}}+(v\\prime\\prime =0) bands include precise line assignments, term values, band-integrated oscillator strengths as well as individual ro-vibrational oscillator strengths and Hönl–London corrections. For ({v}\\prime =1) our results are compared with earlier studies. The interpretation of mixed perturbing bands, complementing an earlier study, is also presented as well as precise line assignments and term values for the B {}1{{{Σ }}}+–X {}1{{{Σ }}}+(0–0) band calibrator, and the nearby B–X (1–0) and C {}1{{{Σ }}}+–X {}1{{{Σ }}}+(0–0) bands.

  4. Herschel/HIFI CO, ^{13}CO and H_2O thermal emission in Water Fountain stars

    NASA Astrophysics Data System (ADS)

    García-García, E.; Rizzo, J. R.; Gómez, J. F.

    2015-05-01

    Water fountain stars are low- and intermediate-mass (0.8-8 M_⊙) evolved object whose water maser emission trace high velocity (>100 km s^{-1}) bipolar jets. They can be found in late AGB phase up to young PNe, although most of them are in the post-AGB phase. These stars may be key objects to understand how planetary nebulae are shaped. Besides the jets, WFs are expected to be surrounded by a large envelope expelled during the AGB and, in some cases, by a circumstellar toroid. We present a study of thermal lines (mid and high-J CO and ^{13}CO, and the lowest transitions of H_2O) from 8 WFs with the Herschel Space Observatory, in order to characterise their circumstellar material. The detected lines have been analysed with LTE and LVG models, to obtain the parameters of their circumstellar envelops. Our results also suggest the presence of thermal emission associated with the outflows. Isotope ratios of CO are compared with those in other post-AGB stars.

  5. Rotational excitation of HCN by para- and ortho-H{sub 2}

    SciTech Connect

    Vera, Mario Hernández; Kalugina, Yulia; Denis-Alpizar, Otoniel; Stoecklin, Thierry; Lique, François

    2014-06-14

    Rotational excitation of the hydrogen cyanide (HCN) molecule by collisions with para-H{sub 2}( j = 0, 2) and ortho-H{sub 2}( j = 1) is investigated at low temperatures using a quantum time independent approach. Both molecules are treated as rigid rotors. The scattering calculations are based on a highly correlated ab initio 4-dimensional (4D) potential energy surface recently published. Rotationally inelastic cross sections among the 13 first rotational levels of HCN were obtained using a pure quantum close coupling approach for total energies up to 1200 cm{sup −1}. The corresponding thermal rate coefficients were computed for temperatures ranging from 5 to 100 K. The HCN rate coefficients are strongly dependent on the rotational level of the H{sub 2} molecule. In particular, the rate coefficients for collisions with para-H{sub 2}( j = 0) are significantly lower than those for collisions with ortho-H{sub 2}( j = 1) and para-H{sub 2}( j = 2). Propensity rules in favor of even Δj transitions were found for HCN in collisions with para-H{sub 2}( j = 0) whereas propensity rules in favor of odd Δj transitions were found for HCN in collisions with H{sub 2}( j ⩾ 1). The new rate coefficients were compared with previously published HCN-para-H{sub 2}( j = 0) rate coefficients. Significant differences were found due the inclusion of the H{sub 2} rotational structure in the scattering calculations. These new rate coefficients will be crucial to improve the estimation of the HCN abundance in the interstellar medium.

  6. Terrestrial cycling of 13CO2 by photosynthesis, respiration, and biomass burning in SiBCASA

    NASA Astrophysics Data System (ADS)

    van der Velde, I. R.; Miller, J. B.; Schaefer, K.; van der Werf, G. R.; Krol, M. C.; Peters, W.

    2014-12-01

    We present an enhanced version of the SiBCASA terrestrial biosphere model that is extended with (a) biomass burning emissions from the SiBCASA carbon pools using remotely sensed burned area from the Global Fire Emissions Database (GFED), (b) an isotopic discrimination scheme that calculates 13C signatures of photosynthesis and autotrophic respiration, and (c) a separate set of 13C pools to carry isotope ratios into heterotrophic respiration. We quantify in this study the terrestrial exchange of CO2 and 13CO2 as a function of environmental changes in humidity and biomass burning. The implementation of biomass burning yields similar fluxes as CASA-GFED both in magnitude and spatial patterns. The implementation of isotope exchange gives a global mean discrimination value of 15.2‰, ranges between 4 and 20‰ depending on the photosynthetic pathway in the plant, and compares favorably (annually and seasonally) with other published values. Similarly, the isotopic disequilibrium is similar to other studies that include a small effect of biomass burning as it shortens the turnover of carbon. In comparison to measurements, a newly modified starch/sugar storage pool propagates the isotopic discrimination anomalies to respiration much better. In addition, the amplitude of the drought response by SiBCASA is lower than suggested by the measured isotope ratios. We show that a slight increase in the stomatal closure for large vapor pressure deficit would amplify the respired isotope ratio variability. Our study highlights the importance of isotope ratio observations of 13C to assess and improve biochemical models like SiBCASA, especially with regard to the allocation and turnover of carbon and the responses to drought.

  7. Serotonin modulates spike probability in the axon initial segment through HCN channels.

    PubMed

    Ko, Kwang Woo; Rasband, Matthew N; Meseguer, Victor; Kramer, Richard H; Golding, Nace L

    2016-06-01

    The axon initial segment (AIS) serves as the site of action potential initiation in most neurons, but difficulties in isolating the effects of voltage-gated ion channels in the AIS from those of the soma and dendrites have hampered understanding how AIS properties influence neural coding. Here we have combined confocal microscopy, patch-clamp recordings and light-sensitive channel blockers ('photoswitches') in binaural auditory gerbil neurons to show that hyperpolarization and cyclic-nucleotide-gated (HCN) channels are expressed in the AIS and decrease spike probability, in a manner distinct from that of HCN channels in the soma and dendrites. Furthermore, the control of spike threshold by HCN channels in the AIS can be altered through serotonergic modulation of 5-hydroxytryptamine 1A (5-HT1A) receptors, which hyperpolarizes the activation range of HCN channels. As release of serotonin signals changes in motivation and attention states, axonal HCN channels provide a mechanism to translate these signals into changes in the threshold for sensory stimuli. PMID:27110919

  8. (abstract) Neptune: CO and HCN Distributions from Observations at the CSO

    NASA Technical Reports Server (NTRS)

    Spilker, T. R.; Gulkis, S.; Salez, M.; Encrenaz, T.

    1994-01-01

    We used the Caltech Submillimeter Observatory (CSO ) to make spatially unresolved observations of the 230.538 GHz 2-1 transition of CO and the 265.886 GHz 3-2 transition of HCN at Neptune. All observations used the 10.4 meter antenna with a double sideband SIS junction heterodyne receiver. Spectra were observed with parallel acousto-optic spectrometers simultaneously providing 580 MHz bandwidth at 0.57 MHz resolution and 50 MHz bandwidth at 0.049 MHz resolution. Observed line shapes agree with prior observations by Rosenqvist et al and Marten et al. Analysis of the line shapes and intensities will yield information about the distributions of CO and HCN in the stratosphere of Neptune, and these results will be compared with previous results. The data imply that the mixing ratios of CO and HCN must decrease with altitude somewhere within the pressure range from 1 to 0.001 mbar. HCN data will also address the sharp saturation-induced decrease in the HCN mixing ratio at the lower levels in the stratosphere.

  9. Association Reactions at Low Pressure: 5. The CH(sub 3)+/HCN System. A Final Word?

    NASA Technical Reports Server (NTRS)

    Anicich, V.; Sen, A.; Huntress, W.; McEwan, M.

    1994-01-01

    The reaction of the methyl cation with hydrogen cyanide is revisited. We have confidence that we have resolved a long standing apparent contradiction of experimental results. A literature history is presented along with one new experiment and a reexamination of an old experiment. In this present work it is shown that all of the previous studies had made consistent observations. Yet, each of the previous studies failed to observe all of the information present. The methyl cation does react with HCN by radiative association, a fact which had been in doubt. The product ions formed in the two-body and three-body processes react differently with HCN. The collisionally stabilized association product formed by a three-body mechanism does not react with HCN and is readily detected in the experiments. The radiatively stabilized association product, formed by a slow two-body reaction, is not detected because it reacts with HCN by a fast proton transfer reaction forming the protonated HCN ion.

  10. Organics Produced by Irradiation of Frozen and Liquid HCN Solutions: Implications for Chemical Evolution Studies

    NASA Astrophysics Data System (ADS)

    Colín-García, M.; Negrón-Mendoza, A.; Ramos-Bernal, S.

    2009-04-01

    Hydrogen cyanide (HCN), an important precursor of organic compounds, is widely present in extraterrestrial environments. HCN is also readily synthesized in prebiotic simulation experiments. To gain insight into the radiation chemistry of one of the most important and highly versatile constituents of cometary ices, we examined the behavior of over-irradiated frozen and liquid HCN solutions under ionizing radiation. The samples were exposed to gamma radiation at a dose range from 0 up to 419 kGy. Ultraviolet spectroscopy and gas chromatography were used to follow the process. The analyses confirmed that gamma-ray irradiation of liquid HCN solutions generates several organic products. Many of them are essential to life; we verified the presence of carboxylic acids (some of them members of the Krebs cycle) as well as free amino acids and urea. These are the first studies to reveal the presence of these compounds in experiments performed at low temperatures and bulk irradiation. Organic material was produced even at low temperatures and low radiation doses. This work strongly supports the presumption that, as a parent molecule, HCN played a central essential role in the process of chemical evolution on early Earth, comets, and other extraterrestrial environments.

  11. Synthesis of HCN and HNC in Ion-Irradiated N2-Rich Ices

    NASA Technical Reports Server (NTRS)

    Moore, M. H.; Hudson, R. L.; Ferrante, R. F.

    2002-01-01

    Near-IR observations reveal that N2-rich ice containing small amounts of CH4, and CO, is abundant on the surfaces of Triton, a moon of Neptune, and Pluto. N2-rich ices may also exist, in interstellar environments. To investigate the radiation chemistry of such ices we performed a systematic IR study of ion-irradiated Nz-rich mixtures containing CH4 and CO. Irradiation of N2 + CH4 mixtures at 12 K, showed that HCN, HNC, diazomethane, and NH3 were produced. We also found that UV photolysis of these ices produced detectable HCN and HNC. Intrinsic band strengths, A(HCN) and A(HNC), were measured and used to calculate yields of HCN and HNC. Similar results were obtained on irradiation of N2 + CH4 + CO ices at 12 K, with the main difference being the formation of HNCO. In all cases we observed changes on warming. For example, when the temperature of irradiated Nz + CH4 + CO was raised from 12 to 30 K, HCN, HNC, and HNCO reacted with NH3, and OCN-, CN-, N3-, and NH4+ were produced. These ions, appearing at 30 K, are expected to form and survive on the surfaces of Triton, Pluto, and interstellar grains. Our results have astrobiological implications since some of these radiation products are involved in the syntheses of biomolecules such as amino acids and peptides.

  12. 13CO 1-0 imaging of the Medusa merger, NGC 4194. Large scale variations in molecular cloud properties

    NASA Astrophysics Data System (ADS)

    Aalto, S.; Beswick, R.; Jütte, E.

    2010-11-01

    Aims: Studying molecular gas properties in merging galaxies gives important clues to the onset and evolution of interaction-triggered starbursts. The frac{12CO}{13CO} line intensity ratio can be used as a tracer of how dynamics and star formation processes impact the gas properties. The Medusa merger (NGC 4194) is particularly interesting to study since its {L_FIRover L_CO} ratio rivals that of ultraluminous galaxies (ULIRGs), despite the comparatively modest luminosity, indicating an exceptionally high star formation efficiency (SFE) in the Medusa merger. Methods: High resolution OVRO (Owens Valley Radio Observatory) observations of the 13CO 1-0 have been obtained and compared with matched resolution OVRO 12CO 1-0 data to investigate the molecular gas cloud properties in the Medusa merger. Results: Interferometric observations of 12CO and 13CO 1-0 in the Medusa (NGC 4194) merger show the {{12CO} over {13CO}} 1-0 intensity ratio ({\\cal R}) increases from normal, quiescent values (7-10) in the outer parts (r > 2 kpc) of the galaxy to high (16 to > 40) values in the central (r < 1 kpc) starburst region. In the central two kpc there is an east-west gradient in {\\cal R} where the line ratio changes by more than a factor of three over 5” (945 pc). The integrated 13CO emission peaks in the north-western starburst region while the central 12CO emission is strongly associated with the prominent crossing dust-lane. Conclusions: We discuss the central east-west gradient in {\\cal R} in the context of gas properties in the starburst and the central dust lane. We suggest that the central gradient in {\\cal R} is mainly caused by diffuse gas in the dust lane. In this scenario, the actual molecular mass distribution is better traced by the 13CO 1-0 emission than the 12CO. The possibilities of temperature and abundance gradients are also discussed. We compare the central gas properties of the Medusa to those of other minor mergers and suggest that the extreme and transient

  13. Constraining Ecosystem Gross Primary Production and Transpiration with Measurements of Photosynthetic 13CO2 Discrimination

    NASA Astrophysics Data System (ADS)

    Blonquist, J. M.; Wingate, L.; Ogeé, J.; Bowling, D. R.

    2011-12-01

    The stable carbon isotope composition of atmospheric CO2 (δ13Ca) can provide useful information on water use efficiency (WUE) dynamics of terrestrial ecosystems and potentially constrain models of CO2 and water fluxes at the land surface. This is due to the leaf-level relationship between photosynthetic 13CO2 discrimination (Δ), which influences δ13Ca, and the ratio of leaf intercellular to atmospheric CO2 mole fractions (Ci / Ca), which is related to WUE and is determined by the balance between C assimilation (CO2 demand) and stomatal conductance (CO2 supply). We used branch-scale Δ derived from tunable diode laser absorption spectroscopy measurements collected in a Maritime pine forest to estimate Ci / Ca variations over an entire growing season. We combined Ci / Ca estimates with rates of gross primary production (GPP) derived from eddy covariance (EC) to estimate canopy-scale stomatal conductance (Gs) and transpiration (T). Estimates of T were highly correlated to T estimates derived from sapflow data (y = 1.22x + 0.08; r2 = 0.61; slope P < 0.001) and T predictions from an ecosystem model (MuSICA) (y = 0.88x - 0.05; r2 = 0.64; slope P < 0.001). As an alternative to estimating T, Δ measurements can be used to estimate GPP by combining Ci / Ca estimates with Gs estimates from sapflow data. Estimates of GPP were determined in this fashion and were highly correlated to GPP values derived from EC (y = 0.82 + 0.07; r2 = 0.61; slope P < 0.001) and GPP predictions from MuSICA (y = 1.10 + 0.42; r2 = 0.50; slope P < 0.001). Results demonstrate that the leaf-level relationship between Δ and Ci / Ca can be extended to the canopy-scale and that Δ measurements have utility for partitioning ecosystem-scale CO2 and water fluxes.

  14. Loss of HCN1 enhances disease progression in mouse models of CNG channel-linked retinitis pigmentosa and achromatopsia.

    PubMed

    Schön, Christian; Asteriti, Sabrina; Koch, Susanne; Sothilingam, Vithiyanjali; Garcia Garrido, Marina; Tanimoto, Naoyuki; Herms, Jochen; Seeliger, Mathias W; Cangiano, Lorenzo; Biel, Martin; Michalakis, Stylianos

    2016-03-15

    Most inherited blinding diseases are characterized by compromised retinal function and progressive degeneration of photoreceptors. However, the factors that affect the life span of photoreceptors in such degenerative retinal diseases are rather poorly understood. Here, we explore the role of hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) in this context. HCN1 is known to adjust retinal function under mesopic conditions, and although it is expressed at high levels in rod and cone photoreceptor inner segments, no association with any retinal disorder has yet been found. We investigated the effects of an additional genetic deletion of HCN1 on the function and survival of photoreceptors in a mouse model of CNGB1-linked retinitis pigmentosa (RP). We found that the absence of HCN1 in Cngb1 knockout (KO) mice exacerbated photoreceptor degeneration. The deleterious effect was reduced by expression of HCN1 using a viral vector. Moreover, pharmacological inhibition of HCN1 also enhanced rod degeneration in Cngb1 KO mice. Patch-clamp recordings revealed that the membrane potentials of Cngb1 KO and Cngb1/Hcn1 double-KO rods were both significantly depolarized. We also found evidence for altered calcium homeostasis and increased activation of the protease calpain in Cngb1/Hcn1 double-KO mice. Finally, the deletion of HCN1 also exacerbated degeneration of cone photoreceptors in a mouse model of CNGA3-linked achromatopsia. Our results identify HCN1 as a major modifier of photoreceptor degeneration and suggest that pharmacological inhibition of HCN channels may enhance disease progression in RP and achromatopsia patients. PMID:26740549

  15. Vibration-rotation variational calculations - Precise results on HCN up to 25,000/cm

    NASA Astrophysics Data System (ADS)

    Carter, Stuart; Mills, Ian M.; Handy, Nicholas C.

    1993-09-01

    Variation calculations of the vibration-rotation energy levels of many isotopomers of HCN are reported, for J = 0, 1, and 2, extending up to approximately 8 quanta of each of the stretching vibrations and 14 quanta of the bending mode. The force field, which is represented as a polynomial expansion in Morse coordinates for the bond stretches and even powers of the angle bend, has been refined by least squares to fit simultaneously all observed data on the Sigma and Pi state vibrational energies, and the Sigma state rotational constants, for both HCN and DCN. The observed vibrational energies are fitted to roughly +/- 0.5/cm, and the rotational constants to roughly +/- 0.0001/cm. The force field has been used to predict the vibration rotation spectra of many isotopomers of HCN up to 25,000/cm.

  16. Output power stability of a HCN laser using a stepping motor for the EAST interferometer system

    NASA Astrophysics Data System (ADS)

    Zhang, J. B.; Wei, X. C.; Liu, H. Q.; Shen, J. J.; Zeng, L.; Jie, Y. X.

    2015-11-01

    The HCN laser on EAST is a continuous wave glow discharge laser with 3.4 m cavity length and 120 mW power output at 337 μ m wavelength. Without a temperature-controlled system, the cavity length of the laser is very sensitive to the environmental temperature. An external power feedback control system is applied on the HCN laser to stabilize the laser output power. The feedback system is composed of a stepping motor, a PLC, a supervisory computer, and the corresponding control program. One step distance of the stepping motor is 1 μ m and the time response is 0.5 s. Based on the power feedback control system, a stable discharge for the HCN laser is obtained more than eight hours, which satisfies the EAST experiment.

  17. Submillimeter-HCN Diagram for Energy Diagnostics in the Centers of Galaxies

    NASA Astrophysics Data System (ADS)

    Izumi, Takuma; Kohno, Kotaro; Aalto, Susanne; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hatsukade, Bunyo; Hsieh, Pei-Ying; Imanishi, Masatoshi; Krips, Melanie; Martín, Sergio; Matsushita, Satoki; Meier, David S.; Nakai, Naomasa; Nakanishi, Kouichiro; Schinnerer, Eva; Sheth, Kartik; Terashima, Yuichi; Turner, Jean L.

    2016-02-01

    Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4-3)/HCO+(4-3) and/or HCN(4-3)/CS(7-6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO+ and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even ≳10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral-neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.

  18. Measurements of the H2(13)CO ortho/para ratio in cold dark molecular clouds

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Dickens, J. E.; Irvine, W. M.; McGonagle, D.

    1995-01-01

    H2(13)CO has been detected for the first time toward cold dark molecular clouds using the NRAO 12 m telescope. The H2(13)CO ortho/para abundance ratio R for B335, which we report as R approximately 1.7, suggests equilibrium at the local kinetic temperature and appears to be distinctly different from that for both TMC-1 and L134N, where R is close to or higher than the statistical value 3. Since only B335 among the observed positions includes an imbedded IR source, this difference may result from heating of the grain surfaces, providing the energy necessary for desorption of formaldehyde formed on the grains.

  19. Negative ion mass spectrometry and the detection of carbonyls and HCN from clover

    NASA Astrophysics Data System (ADS)

    Custer, Thomas G.; Kato, Shuji; Fall, Ray; Bierbaum, Veronica M.

    2000-12-01

    We have demonstrated that negative ion-chemical ionization mass spectrometry (NI-CIMS) can be used to distinguish several isomeric volatile organic compounds (VOCs) that are emitted from wounded plants. Reaction chemistry with HO-, hydrogen/deuterium exchange patterns, and collision-induced dissociation spectra allow identification of the isomers. Laboratory studies of emissions from wounded clover using NI-CIMS show several previously detected VOCs, but also clearly demonstrate the emission of HCN. This compound is presumably formed by the decomposition of cyanogenic glycosides which also form aldehyde and ketone byproducts. These results suggest that NI-CIMS may be a valuable tool for investigating VOCs and HCN release from vegetation.

  20. Quartz-enhanced photoacoustic spectroscopy of HCN from 6433 to 6613 cm-1

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Zhao, Weixiong; Wang, Lei; tan, Tu; Wang, Guishi; Zhang, Weijun; Gao, Xiaoming; Chen, Weidong

    2015-04-01

    We developed a spectrometer based on quartz-enhanced photoacoustic spectroscopy. A widely and continuously tunable fiber-coupled telecom-grade external cavity diode laser was used as a spectroscopic source. The hydrogen cyanide (HCN) absorption spectrum in the near-infrared spectral region from 6433 to 6613 cm-1 was measured. The spectrum of P branch of (2000)-(0000) band of HCN was analyzed. The analyzed results are in excellent agreement with published reference absorption spectra and given by the GEISA03 database.

  1. Method for tracing simulated CO2 leak in terrestrial environment with a 13CO2 tracer

    NASA Astrophysics Data System (ADS)

    Moni, Christophe; Rasse, Daniel

    2013-04-01

    Facilities for the geological storage of carbon dioxide (CO2) as part of carbon capture and storage (CCS) schemes will be designed to prevent any leakage from the defined 'storage complex'. However, developing regulations and guidance throughout the world (e.g. the EC Directive and the USEPA Vulnerability Evaluation Framework) recognize the importance of assessing the potential for environmental impacts from CO2 storage. RISCS, a European (FP7) project, aims to improve understanding of those impacts that could plausibly occur in the hypothetical case that unexpected leakage occurs. As part of the RISCS project the potential impacts that an unexpected CO2 leaks might have on a cropland ecosystems was investigated. A CO2 exposure field experiment based on CO2 injection at 85 cm depth under an oats culture was designed. To facilitate the characterization of the simulated leaking zone the gas used for injection was produced from natural gas and had a δ13C of -46‰. The aim of the present communication is to depict how the injected gas was traced within the soil-vegetation-atmosphere continuum using 13CO2 continuous cavity ring-down spectrometry (CRDS). Four subsurface experimental injection plots (6m x 3m) were set up. In order to test the effects of different intensity of leakage, the field experiment was designed as to create a longitudinal CO2 gradient for each plot. For this purpose gas supply pipes were inserted at one extremity of each plot at the base of a 45 cm thick layer of sand buried 40 cm below the surface under the clayey plough layer of Norwegian moraine soils. Soil CO2 concentration and isotopic signature were punctually recorded: 1) in the soil at 20 cm depth at 6 positions distributed on the central transect, 2) at the surface following a (50x50 cm) grid sampling pattern, and 3) in the canopy atmosphere at 10, 20, 30 cm along three longitudinal transects (seven sampling point per transect). Soil CO2 fluxes and isotopic signature were finally

  2. An N-Terminal ER Export Signal Facilitates the Plasma Membrane Targeting of HCN1 Channels in Photoreceptors

    PubMed Central

    Pan, Yuan; Laird, Joseph G.; Yamaguchi, David M.; Baker, Sheila A.

    2015-01-01

    Purpose. Hyperpolarization-activated cyclic nucleotide-gated 1 (HCN1) channels are widely expressed in the retina. In photoreceptors, the hyperpolarization-activated current (Ih) carried by HCN1 is important for shaping the light response. It has been shown in multiple systems that trafficking HCN1 channels to specific compartments is key to their function. The localization of HCN1 in photoreceptors is concentrated in the plasma membrane of the inner segment (IS). The mechanisms controlling this localization are not understood. We previously identified a di-arginine endoplasmic reticulum (ER) retention motif that negatively regulates the surface targeting of HCN1. In this study, we sought to identify a forward trafficking signal that could counter the function of the ER retention signal. Methods. We studied trafficking of HCN1 and several mutants by imaging their subcellular localization in transgenic X. laevis photoreceptors. Velocity sedimentation was used to assay the assembly state of HCN1 channels. Results. We found the HCN1 N-terminus can redirect a membrane reporter from outer segments (OS) to the plasma membrane of the IS. The sequence necessary for this behavior was mapped to a 20 amino acid region containing a leucine-based ER export motif. The ER export signal is necessary for forward trafficking but not channel oligomerization. Moreover, this ER export signal alone counteracted the di-arginine ER retention signal. Conclusions. We identified an ER export signal in HCN1 that functions with the ER retention signal to maintain equilibrium of HCN1 between the endomembrane system and the plasma membrane. PMID:26030105

  3. Photodissociation of HCN and HNC isomers in the 7-10 eV energy range

    NASA Astrophysics Data System (ADS)

    Chenel, Aurelie; Roncero, Octavio; Aguado, Alfredo; Agúndez, Marcelino; Cernicharo, José

    2016-04-01

    The ultraviolet photoabsorption spectra of the HCN and HNC isomers have been simulated in the 7-10 eV photon energy range. For this purpose, the three-dimensional adiabatic potential energy surfaces of the 7 lowest electronic states, and the corresponding transition dipole moments, have been calculated, at multireference configuration interaction level. The spectra are calculated with a quantum wave packet method on these adiabatic potential energy surfaces. The spectra for the 3 lower excited states, the dissociative electronic states, correspond essentially to predissociation peaks, most of them through tunneling on the same adiabatic state. The 3 higher electronic states are bound, hereafter electronic bound states, and their spectra consist of delta lines, in the adiabatic approximation. The radiative lifetime towards the ground electronic states of these bound states has been calculated, being longer than 10 ns in all cases, much longer that the characteristic predissociation lifetimes. The spectra of HCN is compared with the available experimental and previous theoretical simulations, while in the case of HNC there are no previous studies to our knowledge. The spectrum for HNC is considerably more intense than that of HCN in the 7-10 eV photon energy range, which points to a higher photodissociation rate for HNC, compared to HCN, in astrophysical environments illuminated by ultraviolet radiation.

  4. First-principles insights into interaction of CO, NO, and HCN with Ag{sub 8}

    SciTech Connect

    Torbatian, Zahra; Hashemifar, S. Javad Akbarzadeh, Hadi

    2014-02-28

    We use static as well as time-dependent first-principles computations to study interaction of the CO, NO, and HCN molecules with the Ag{sub 8} nanocluster. The many-body based GW correction is applied for accurate description of the highest occupied (HOMO) and the lowest unoccupied (LUMO) molecular orbital levels. It is argued that the adsorption of these molecules changes the stable structure of Ag{sub 8} from Td to the more chemically active D{sub 2d} symmetry. We discuss that the CO, NO, and HCN molecules prefer to adsorb on the atom of the cluster with significant contribution to both HOMO and LUMO, for the accomplishment of the required charge transfers in the systems. The charge back donation is found to leave an excess energy of about 110 meV on the NO molecular bond, evidencing potential application of silver clusters for NO reduction. It is argued that CO and specially NO exhibit strong physical interaction with the silver cluster and hence significantly modify the electronic and optical properties of the system, while HCN makes very week physical bonds with the cluster. The optical absorption spectra of the Ag{sub 8} cluster before and after molecule adsorption are computed and a nontrivial red shift is observed in the NO and HCN adsorbed clusters.

  5. Photodissociation of HCN and HNC isomers in the 7-10 eV energy range

    PubMed Central

    Chenel, Aurelie; Roncero, Octavio; Aguado, Alfredo; Agúndez, Marcelino; Cernicharo, José

    2016-01-01

    The ultraviolet photoabsorption spectra of the HCN and HNC isomers have been simulated in the 7-10 eV photon energy range. For this purpose the three-dimensional adiabatic potential energy surfaces of the 7 lowest electronic states, and the corresponding transition dipole moments, have been calculated, at multi reference configuration interaction level. The spectra are calculated with a quantum wave packet method on these adiabatic potential energy surfaces. The spectra for the 3 lower excited states, the dissociative electronic states, correspond essentially to predissociation peaks, most of them through tunneling on the same adiabatic state. The 3 higher electronic states are bound, hereafter electronic bound states, and their spectra consist of delta lines, in the adiabatic approximation. The radiative lifetime towards the ground electronic states of these bound states have been calculated, being longer than 10 ns in all cases, much longer that the characteristic predissociation lifetimes. The spectra of HCN is compared with the available experimental and previous theoretical simulations while in the case of HNC there are no previous studies to our knowledge. The spectrum for HNC is considerably more intense than that of HCN, which implies a much faster destruction of HNC than HCN in astrophysical environments illuminated by ultraviolet radiation. PMID:27083720

  6. Formation of HCN+ in Heterogeneous Reactions of N2+ and N+ with Surface Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Harnisch, Martina; Keim, Alan; Scheier, Paul; Herman, Zdenek

    2013-10-01

    A significant increase of the ion yield at m/z 27 in collisions of low-energy ions of N2+ and N+ with hydrocarbon-covered room-temperature or heated surfaces of tungsten, carbon-fiber composite, and beryllium, not observed in analogous collisions of Ar+, is ascribed to the formation of HCN+ in heterogeneous reactions between N2+ or N+ and surface hydrocarbons. The formation of HCN+ in the reaction with N+ indicated an exothermic reaction with no activation barrier, likely to occur even at very low collision energies. In the reaction with N2+, the formation of HCN+ was observed to a different degree on these room-temperature and heated (150 and 300 °C) surfaces at incident energies above about 50 eV. This finding suggested an activation barrier or reaction endothermicity of the heterogeneous reaction of about 3-3.5 eV. The main process in N2+ or N+ interaction with the surfaces is ion neutralization; the probability of forming the reaction product HCN+ was very roughly estimated for both N2+ and N+ ions to about one in 104 collisions with the surfaces.

  7. Photodissociation of HCN and HNC isomers in the 7-10 eV energy range.

    PubMed

    Chenel, Aurelie; Roncero, Octavio; Aguado, Alfredo; Agúndez, Marcelino; Cernicharo, José

    2016-04-14

    The ultraviolet photoabsorption spectra of the HCN and HNC isomers have been simulated in the 7-10 eV photon energy range. For this purpose, the three-dimensional adiabatic potential energy surfaces of the 7 lowest electronic states, and the corresponding transition dipole moments, have been calculated, at multireference configuration interaction level. The spectra are calculated with a quantum wave packet method on these adiabatic potential energy surfaces. The spectra for the 3 lower excited states, the dissociative electronic states, correspond essentially to predissociation peaks, most of them through tunneling on the same adiabatic state. The 3 higher electronic states are bound, hereafter electronic bound states, and their spectra consist of delta lines, in the adiabatic approximation. The radiative lifetime towards the ground electronic states of these bound states has been calculated, being longer than 10 ns in all cases, much longer that the characteristic predissociation lifetimes. The spectra of HCN is compared with the available experimental and previous theoretical simulations, while in the case of HNC there are no previous studies to our knowledge. The spectrum for HNC is considerably more intense than that of HCN in the 7-10 eV photon energy range, which points to a higher photodissociation rate for HNC, compared to HCN, in astrophysical environments illuminated by ultraviolet radiation. PMID:27083720

  8. Patch-clamp fluorometry-based channel counting to determine HCN channel conductance.

    PubMed

    Liu, Chang; Xie, Changan; Grant, Khade; Su, Zhuocheng; Gao, Weihua; Liu, Qinglian; Zhou, Lei

    2016-07-01

    Counting ion channels on cell membranes is of fundamental importance for the study of channel biophysics. Channel counting has thus far been tackled by classical approaches, such as radioactive labeling of ion channels with blockers, gating current measurements, and nonstationary noise analysis. Here, we develop a counting method based on patch-clamp fluorometry (PCF), which enables simultaneous electrical and optical recordings, and apply it to EGFP-tagged, hyperpolarization-activated and cyclic nucleotide-regulated (HCN) channels. We use a well-characterized and homologous cyclic nucleotide-gated (CNG) channel to establish the relationship between macroscopic fluorescence intensity and the total number of channels. Subsequently, based on our estimate of the total number of HCN channels, we determine the single-channel conductance of HCN1 and HCN2 to be 0.46 and 1.71 pS, respectively. Such a small conductance would present a technical challenge for traditional electrophysiology. This PCF-based technique provides an alternative method for counting particles on cell membranes, which could be applied to biophysical studies of other membrane proteins. PMID:27353446

  9. Fourier-Transform Microwave and Millimeterwave Spectroscopy of the H2-HCN Molecular Complex

    NASA Astrophysics Data System (ADS)

    Tanaka, Keiichi; Harada, Kensuke; Sumiyoshi, Yoshihiro; Nakajima, Masakazu; Endo, Yasuki

    2015-06-01

    Fourier-Transform microwave (FTMW) spectroscopy has been applied to observe the J = 1 - 0 rotational transitions of the H2-HCN/DCN complexes containing both the para-H2 (IH2=0) and ortho-H2 (IH2=1) molecule Rotational spectra of H2-HCN/DCN up to J = 5 - 4 were also observed in the millimeter-wave (MMW) region below 180 GHz. Observed FTMW lines for H2-HCN/DCN split into hyperfine components due to the nuclear quadrupole interaction of N and D nuclei. For the ortho-H2 species, the hyperfine splitting due to the magnetic interaction between the hydrogen nuclear spin of ortho-H2 part (jH2=1, IH2=1) was also observed, but not for the para-H2 species (jH2=0, IH2=0). From the observed nuclear spin-spin coupling constants of ortho-H2 species, d = 21.90(47) and 24.66(68) kHz for HCN and DCN complexes, respectively, the average values of = 0.380(8) and 0.439(10) were derived indicating the nearly free rotation of H2 in the complex with jH2= 1 and kH2= 0. The nuclear quadrupole interaction constants due to N and D nuclei show that the HCN/DCN part executes a floppy motion with a large mean square amplitude of about 29/25 and 33/30 degree in the para and ortho species, respectively. From the observed rotational constants, the center-of-mass distances of H2 and HCN/DCN were derived to be 3.9617(5)/4.00356 (43) Å for the ortho species and 4.1589(13)/4.1596 (36) Å for the para species. The isotope effect on rotational constants confirmed the totally different configurations in the ortho and para species: H2 is attached to the H/D end of HCN/DCN for the para species, while to the N end for the ortho species, as suggested by IR spectroscopy and theoretical study. M. Ishiguro et al., Chem. Phys. Lett. 554, 33 (2012). M. Ishiguro et al., J. Chem. Phys. 115, 5155 (2001).

  10. The abundance of HCN in circumstellar envelopes of AGB stars of different chemical type

    NASA Astrophysics Data System (ADS)

    Schöier, F. L.; Ramstedt, S.; Olofsson, H.; Lindqvist, M.; Bieging, J. H.; Marvel, K. B.

    2013-02-01

    Aims: A multi-transition survey of HCN (sub-) millimeter line emission from a large sample of asymptotic giant branch (AGB) stars of different chemical type is presented. The data are analysed and circumstellar HCN abundances are estimated. The sample stars span a large range of properties such as mass-loss rate and photospheric C/O-ratio. The analysis of the new data allows for more accurate estimates of the circumstellar HCN abundances and puts new constraints on chemical models. Methods: In order to constrain the circumstellar HCN abundance distribution a detailed non-local thermodynamic equilibrium (LTE) excitation analysis, based on the Monte Carlo method, is performed. Effects of line overlaps and radiative excitation from dust grains are included. Results: The median values for the derived abundances of HCN (with respect to H2) are 3 × 10-5, 7 × 10-7 and 10-7 for carbon stars (25 stars), S-type AGB stars (19 stars) and M-type AGB stars (25 stars), respectively. The estimated sizes of the HCN envelopes are similar to those obtained in the case of SiO for the same sample of sources and agree well with previous results from interferometric observations, when these are available. Conclusions: We find that there is a clear dependence of the derived circumstellar HCN abundance on the C/O-ratio of the star, in that carbon stars have about two orders of magnitude higher abundances than M-type AGB stars, on average. The derived HCN abundances of the S-type AGB stars have a larger spread and typically fall in between those of the two other types, however, slightly closer to the values for the M-type AGB stars. For the M-type stars, the estimated abundances are much higher than what would be expected if HCN is formed in thermal equilibrium. However, the results are also in contrast to predictions from recent non-LTE chemical models, where very little difference is expected in the HCN abundances between the various types of AGB stars. This publication is based on data

  11. Calcium regulation of HCN channels supports persistent activity in a multiscale model of neocortex.

    PubMed

    Neymotin, S A; McDougal, R A; Bulanova, A S; Zeki, M; Lakatos, P; Terman, D; Hines, M L; Lytton, W W

    2016-03-01

    Neuronal persistent activity has been primarily assessed in terms of electrical mechanisms, without attention to the complex array of molecular events that also control cell excitability. We developed a multiscale neocortical model proceeding from the molecular to the network level to assess the contributions of calcium (Ca(2+)) regulation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in providing additional and complementary support of continuing activation in the network. The network contained 776 compartmental neurons arranged in the cortical layers, connected using synapses containing AMPA/NMDA/GABAA/GABAB receptors. Metabotropic glutamate receptors (mGluR) produced inositol triphosphate (IP3) which caused the release of Ca(2+) from endoplasmic reticulum (ER) stores, with reuptake by sarco/ER Ca(2+)-ATP-ase pumps (SERCA), and influence on HCN channels. Stimulus-induced depolarization led to Ca(2+) influx via NMDA and voltage-gated Ca(2+) channels (VGCCs). After a delay, mGluR activation led to ER Ca(2+) release via IP3 receptors. These factors increased HCN channel conductance and produced firing lasting for ∼1min. The model displayed inter-scale synergies among synaptic weights, excitation/inhibition balance, firing rates, membrane depolarization, Ca(2+) levels, regulation of HCN channels, and induction of persistent activity. The interaction between inhibition and Ca(2+) at the HCN channel nexus determined a limited range of inhibition strengths for which intracellular Ca(2+) could prepare population-specific persistent activity. Interactions between metabotropic and ionotropic inputs to the neuron demonstrated how multiple pathways could contribute in a complementary manner to persistent activity. Such redundancy and complementarity via multiple pathways is a critical feature of biological systems. Mediation of activation at different time scales, and through different pathways, would be expected to protect against disruption, in

  12. Hcn1 Is a Tremorgenic Genetic Component in a Rat Model of Essential Tremor

    PubMed Central

    Ohno, Yukihiro; Shimizu, Saki; Tatara, Ayaka; Imaoku, Takuji; Ishii, Takahiro; Sasa, Masashi; Serikawa, Tadao; Kuramoto, Takashi

    2015-01-01

    Genetic factors are thought to play a major role in the etiology of essential tremor (ET); however, few genetic changes that induce ET have been identified to date. In the present study, to find genes responsible for the development of ET, we employed a rat model system consisting of a tremulous mutant strain, TRM/Kyo (TRM), and its substrain TRMR/Kyo (TRMR). The TRM rat is homozygous for the tremor (tm) mutation and shows spontaneous tremors resembling human ET. The TRMR rat also carries a homozygous tm mutation but shows no tremor, leading us to hypothesize that TRM rats carry one or more genes implicated in the development of ET in addition to the tm mutation. We used a positional cloning approach and found a missense mutation (c. 1061 C>T, p. A354V) in the hyperpolarization-activated cyclic nucleotide-gated 1 channel (Hcn1) gene. The A354V HCN1 failed to conduct hyperpolarization-activated currents in vitro, implicating it as a loss-of-function mutation. Blocking HCN1 channels with ZD7288 in vivo evoked kinetic tremors in nontremulous TRMR rats. We also found neuronal activation of the inferior olive (IO) in both ZD7288-treated TRMR and non-treated TRM rats and a reduced incidence of tremor in the IO-lesioned TRM rats, suggesting a critical role of the IO in tremorgenesis. A rat strain carrying the A354V mutation alone on a genetic background identical to that of the TRM rats showed no tremor. Together, these data indicate that body tremors emerge when the two mutant loci, tm and Hcn1A354V, are combined in a rat model of ET. In this model, HCN1 channels play an important role in the tremorgenesis of ET. We propose that oligogenic, most probably digenic, inheritance is responsible for the genetic heterogeneity of ET. PMID:25970616

  13. Stacking analysis of 12CO and 13CO spectra of NGC 3627: Existence of non-optically thick 12CO emission?

    NASA Astrophysics Data System (ADS)

    Morokuma-Matsui, Kana; Sorai, Kazuo; Watanabe, Yoshimasa; Kuno, Nario

    2015-02-01

    We stacked 12CO and 13CO spectra of NGC 3627 after redefining the velocity axis of each spectrum of the mapping data so that the zero corresponds to the local mean velocity of the 12CO spectra. The signal-to-noise ratios of the resulting spectra are improved by a factor of up to 3.2 compared to those obtained with normal stacking analysis. We successfully detect a weak 13CO emission from the interarm region where the emission was not detected in the individual pointings. We compare the integrated intensity ratios I_{^{12}{CO}}/I_{^{13}CO} among six characteristic regions (center, bar, bar-end, offset, arm, and interarm). We find that I_{^{12}{CO}}/I_{^{13}CO} in the bar and interarm are higher than those in the other regions by a factor of ˜ 2 and I_{^{12}{CO}}/I_{^{13}CO} in the center is moderately high. These high I_{^{12}{CO}}/I_{^{13}CO} ratios in the bar and center are attributed to a high intensity ratio (T_{^{12}{CO}}/T_{^{13}CO}), and that in the interarm is attributed to a high ratio of the full width at half maximum of spectra (FWHM_{^{12}{CO}}/FWHM_{^{13}CO}). The difference between FWHM_{^{12}CO} and FWHM_{^{13}CO} of the interarm indicates the existence of two components, one with a narrow line width (˜ FWHM_^{13CO}) and the other with a broad line width (˜ FWHM_^{12CO}). Additionally, the T_{^{12}{CO}}/T_{^{13}CO} ratio in the broad-line-width component of the interarm is higher than the other regions. The high T_{^{12}{CO}}/T_{^{13}CO} in the center and bar and of the broad-line-width component in the interarm suggest the existence of non-optically thick 12CO components. We find that more than half of the 12CO emissions of the interarm are likely to be radiated from the diffuse component. Our result suggests that the use of a universal CO-to-H2 conversion factor might lead to an overestimation of molecular gas mass and underestimation of star-formation efficiency in the interarm by a factor of a few.

  14. OPACITY BROADENING OF {sup 13}CO LINEWIDTHS AND ITS EFFECT ON THE VARIANCE-SONIC MACH NUMBER RELATION

    SciTech Connect

    Correia, C.; De Medeiros, J. R.; Burkhart, B.; Lazarian, A.; Ossenkopf, V.; Stutzki, J.; Kainulainen, J.; Kowal, G.

    2014-04-10

    We study how the estimation of the sonic Mach number (M{sub s} ) from {sup 13}CO linewidths relates to the actual three-dimensional sonic Mach number. For this purpose we analyze MHD simulations that include post-processing to take radiative transfer effects into account. As expected, we find very good agreement between the linewidth estimated sonic Mach number and the actual sonic Mach number of the simulations for optically thin tracers. However, we find that opacity broadening causes M{sub s} to be overestimated by a factor of ≈1.16-1.3 when calculated from optically thick {sup 13}CO lines. We also find that there is a dependence on the magnetic field: super-Alfvénic turbulence shows increased line broadening compared with sub-Alfvénic turbulence for all values of optical depth for supersonic turbulence. Our results have implications for the observationally derived sonic Mach number-density standard deviation (σ{sub ρ/(ρ)}) relationship, σ{sub ρ/〈ρ〉}{sup 2}=b{sup 2}M{sub s}{sup 2}, and the related column density standard deviation (σ {sub N/(N)}) sonic Mach number relationship. In particular, we find that the parameter b, as an indicator of solenoidal versus compressive driving, will be underestimated as a result of opacity broadening. We compare the σ {sub N/(N)}-M{sub s} relation derived from synthetic dust extinction maps and {sup 13}CO linewidths with recent observational studies and find that solenoidally driven MHD turbulence simulations have values of σ {sub N/(N)}which are lower than real molecular clouds. This may be due to the influence of self-gravity which should be included in simulations of molecular cloud dynamics.

  15. Photodissociation Dynamics of Vinyl Cyanide Studied by Chirped-Pulse Millimeter-Wave Spectroscopy of HCN and HNC Products

    NASA Astrophysics Data System (ADS)

    Prozument, Kirill; Shaver, Rachel G.; Baraban, Joshua H.; Park, G. Barratt; Suits, Arthur G.; Muenter, John S.; Field, Robert W.

    2013-06-01

    Vinyl cyanide 193 nm photodissociation has been studied using Chirped-Pulse Millimeter-Wave (CPmmW) spectroscopy. J = 0 - 1 transitions of more than 30 vibrationally excited states of the HCN and HNC products have been recorded and assigned within the 7 GHz wide chirp range. Bending excitations of HCN up to v_2 = 14, leading toward the HCN leftrightarrow HNC isomerization transition state, are detected and interpreted in terms of their electric quadrupole, (eQq)_{N}, and rotational, B_v, constants. The photolysis reaction transition states were probed using both normal vinyl cyanide, CH_2=CHCN, and its singly-deuterated isotopologue, CH_2=CDCN. The observed difference in the vibrational population distribution (VPD) obtained from the integrated intensities of the HCN and DCN products from the CH_2=CHCN vs. CH_2=CDCN photolysis reactions, suggests the relative unimportance of the three-center elimination mechanism for HCN production. On the other hand, the similarity in the observed VPD and overall intensities of HCN from CH_2=CHCN and CH_2=CDCN photolysis suggests four-center elimination as the major mechanism leading to the HCN product. Additional J - (J + 1) transitions would be required to characterize both the vibrational and the rotational state distributions of the products, which would permit more complete characterization of the transition state(s). The authors thank the Department of Energy, and KP thanks the ACS Petroleum Research Fund for their support of this work.

  16. Regulation of Axonal HCN1 Trafficking in Perforant Path Involves Expression of Specific TRIP8b Isoforms

    PubMed Central

    Lewis, Alan S.; Stoub, Travis R.; Ramos, Elena M.; Brandt, Nicola; Nicholson, Daniel A.; Chetkovich, Dane M.; Bender, Roland A.

    2012-01-01

    The functions of HCN channels in neurons depend critically on their subcellular localization, requiring fine-tuned machinery that regulates subcellular channel trafficking. Here we provide evidence that regulatory mechanisms governing axonal HCN channel trafficking involve association of the channels with specific isoforms of the auxiliary subunit TRIP8b. In the medial perforant path, which normally contains HCN1 channels in axon terminals in immature but not in adult rodents, we found axonal HCN1 significantly increased in adult mice lacking TRIP8b (TRIP8b−/−). Interestingly, adult mice harboring a mutation that results in expression of only the two most abundant TRIP8b isoforms (TRIP8b[1b/2]−/−) exhibited an HCN1 expression pattern similar to wildtype mice, suggesting that presence of one or both of these isoforms (TRIP8b(1a), TRIP8b(1a-4)) prevents HCN1 from being transported to medial perforant path axons in adult mice. Concordantly, expression analyses demonstrated a strong increase of expression of both TRIP8b isoforms in rat entorhinal cortex with age. However, when overexpressed in cultured entorhinal neurons of rats, TRIP8b(1a), but not TRIP8b(1a-4), altered substantially the subcellular distribution of HCN1 by promoting somatodendritic and reducing axonal expression of the channels. Taken together, we conclude that TRIP8b isoforms are important regulators of HCN1 trafficking in entorhinal neurons and that the alternatively-spliced isoform TRIP8b(1a) could be responsible for the age-dependent redistribution of HCN channels out of perforant path axon terminals. PMID:22363812

  17. On the HCN and CO 2 abundance and distribution in Jupiter's stratosphere

    NASA Astrophysics Data System (ADS)

    Lellouch, E.; Bézard, B.; Strobel, D. F.; Bjoraker, G. L.; Flasar, F. M.; Romani, P. N.

    2006-10-01

    Observations of Jupiter by Cassini/CIRS, acquired during the December 2000 flyby, provide the latitudinal distribution of HCN and CO 2 in Jupiter's stratosphere with unprecedented spatial resolution and coverage. Following up on a preliminary study by Kunde et al. [Kunde, V.G., and 41 colleagues, 2004. Science 305, 1582-1587], the analysis of these observations leads to two unexpected results (i) the total HCN mass in Jupiter's stratosphere in 2000 was (6.0±1.5)×10 g, i.e., at least three times larger than measured immediately after the Shoemaker-Levy 9 (SL9) impacts in July 1994 and (ii) the latitudinal distributions of HCN and CO 2 are strikingly different: while HCN exhibits a maximum at 45° S and a sharp decrease towards high Southern latitudes, the CO 2 column densities peak over the South Pole. The total CO 2 mass is (2.9±1.2)×10 g. A possible cause for the HCN mass increase is its production from the photolysis of NH 3, although a problem remains because, while millimeter-wave observations clearly indicate that HCN is currently restricted to submillibar ( ˜0.3 mbar) levels, immediate post-impact infrared observations have suggested that most of the ammonia was present in the lower stratosphere near 20 mbar. HCN appears to be a good atmospheric tracer, with negligible chemical losses. Based on 1-dimensional (latitude) transport models, the HCN distribution is best interpreted as resulting from the combination of a sharp decrease (over an order of magnitude in K) of wave-induced eddy mixing poleward of 40° and an equatorward transport with ˜7 cms velocity. The CO 2 distribution was investigated by coupling the transport model with an elementary chemical model, in which CO 2 is produced from the conversion of water originating either from SL9 or from auroral input. The auroral source does not appear adequate to reproduce the CO 2 peak over the South Pole, as required fluxes are unrealistically high and the shape of the CO 2 bulge is not properly matched

  18. (13) CO2 /(12) CO2 exchange fluxes in a clamp-on leaf cuvette: disentangling artefacts and flux components.

    PubMed

    Gong, Xiao Ying; Schäufele, Rudi; Feneis, Wolfgang; Schnyder, Hans

    2015-11-01

    Leaks and isotopic disequilibria represent potential errors and artefacts during combined measurements of gas exchange and carbon isotope discrimination (Δ). This paper presents new protocols to quantify, minimize, and correct such phenomena. We performed experiments with gradients of CO2 concentration (up to ±250 μmol mol(-1) ) and δ(13) CCO2 (34‰), between a clamp-on leaf cuvette (LI-6400) and surrounding air, to assess (1) leak coefficients for CO2 , (12) CO2 , and (13) CO2 with the empty cuvette and with intact leaves of Holcus lanatus (C3 ) or Sorghum bicolor (C4 ) in the cuvette; and (2) isotopic disequilibria between net photosynthesis and dark respiration in light. Leak coefficients were virtually identical for (12) CO2 and (13) CO2 , but ∼8 times higher with leaves in the cuvette. Leaks generated errors on Δ up to 6‰ for H. lanatus and 2‰ for S. bicolor in full light; isotopic disequilibria produced similar variation of Δ. Leak errors in Δ in darkness were much larger due to small biological : leak flux ratios. Leak artefacts were fully corrected with leak coefficients determined on the same leaves as Δ measurements. Analysis of isotopic disequilibria enabled partitioning of net photosynthesis and dark respiration, and indicated inhibitions of dark respiration in full light (H. lanatus: 14%, S. bicolor: 58%). PMID:25944155

  19. Raman spectroscopic investigation of 13CO 2 labeling and leaf dark respiration of Fagus sylvatica L. (European beech).

    PubMed

    Keiner, Robert; Gruselle, Marie-Cécile; Michalzik, Beate; Popp, Jürgen; Frosch, Torsten

    2015-03-01

    An important issue, in times of climate change and more extreme weather events, is the investigation of forest ecosystem reactions to these events. Longer drought periods stress the vitality of trees and promote mass insect outbreaks, which strongly affect ecosystem processes and services. Cavity-enhanced Raman gas spectrometry was applied for online multi-gas analysis of the gas exchange rates of O2 and CO2 and the labeling of Fagus sylvatica L. (European beech) seedlings with (13)CO2. The rapid monitoring of all these gases simultaneously allowed for the separation of photosynthetic uptake of CO2 by the beech seedlings and a constant (12)CO2 efflux via respiration and thus for a correction of the measured (12)CO2 concentrations in course of the labeling experiment. The effects of aphid infestation with the woolly beech aphid (Phyllaphis fagi L.) as well as the effect of a drought period on the respirational gas exchange were investigated. A slightly decreased respirational activity of drought-stressed seedlings in comparison to normally watered seedlings was found already for a low drought intensity. Cavity-enhanced Raman gas monitoring of O2, (12)CO2, and (13)CO2 was proven to be a powerful new tool for studying the effect of drought stress and aphid infestation on the respirational activity of European beech seedlings as an example of important forest species in Central Europe. PMID:25577365

  20. Energy yields for hydrogen cyanide and formaldehyde syntheses - The HCN and amino acid concentrations in the primitive ocean

    NASA Technical Reports Server (NTRS)

    Stribling, Roscoe; Miller, Stanley L.

    1987-01-01

    Simulated prebiotic atmospheres containing either CH4, CO, or CO2, in addition to N2, H2O, and variable amounts of H2, were subjected to the spark from a high-frequency Tesla coil, and the energy yields for the syntheses of HCN and H2CO were estimated from periodic (every two days) measurements of the compound concentrations. The mixtures with CH4 were found to yield the highest amounts of HCN, whereas the CO mixtures produced the highest yields of H2CO. These results model atmospheric corona discharges. From the yearly energy yields calculated and the corona discharge available on the earth, the yearly production rate of HCN was estimated; using data on the HCN production rates and the experimental rates of decomposition of amino acids through the submarine vents, the steady state amino acid production rate in the primitive ocean was calculated to be about 10 nmoles/sq cm per year.

  1. Involvement of HCN Channel in Muscarinic Inhibitory Action on Tonic Firing of Dorsolateral Striatal Cholinergic Interneurons

    PubMed Central

    Zhao, Zhe; Zhang, Kang; Liu, Xiaoyan; Yan, Haitao; Ma, Xiaoyun; Zhang, Shuzhuo; Zheng, Jianquan; Wang, Liyun; Wei, Xiaoli

    2016-01-01

    The striatum is the most prominent nucleus in the basal ganglia and plays an important role in motor movement regulation. The cholinergic interneurons (ChIs) in striatum are involved in the motion regulation by releasing acetylcholine (ACh) and modulating the output of striatal projection neurons. Here, we report that muscarinic ACh receptor (M receptor) agonists, ACh and Oxotremorine (OXO-M), decreased the firing frequency of ChIs by blocking the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Scopolamine (SCO), a nonselective antagonist of M receptors, abolished the inhibition. OXO-M exerted its function by activating the Gi/o cAMP signaling cascade. The single-cell reverse transcription polymerase chain reaction (scRT-PCR) revealed that all the five subtypes of M receptors and four subtypes of HCN channels were expressed on ChIs. Among them, M2 receptors and HCN2 channels were the most dominant ones and expressed in every single studied cholinergic interneuron (ChI).Our results suggest that ACh regulates not only the output of striatal projection neurons, but also the firing activity of ChIs themselves by activating presynaptic M receptors in the dorsal striatum. The activation of M2 receptors and blockage of HCN2 channels may play an important role in ACh inhibition on the excitability of ChIs. This finding adds a new G-protein coupled receptor mediated regulation on ChIs and provides a cellular mechanism for control of cholinergic activity and ACh release in the dorsal striatum. PMID:27047336

  2. Extended HCN and HCO+ Emission in the Starburst Galaxy M82

    NASA Astrophysics Data System (ADS)

    Salas, P.; Galaz, G.; Salter, D.; Herrera-Camus, R.; Bolatto, A. D.; Kepley, A.

    2014-12-01

    We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO+, HNC, CS, and HC3N lines, but here we focus on the HCN and HCO+ emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO+ observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO+ J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 106 M ⊙ and 21 × 106 M ⊙, or >~ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is >=0.3 M ⊙ yr-1, which would lower the starburst lifetime by >=5%. The energy required to expel this mass of dense gas is (1-10) × 1052 erg.

  3. Involvement of HCN Channel in Muscarinic Inhibitory Action on Tonic Firing of Dorsolateral Striatal Cholinergic Interneurons.

    PubMed

    Zhao, Zhe; Zhang, Kang; Liu, Xiaoyan; Yan, Haitao; Ma, Xiaoyun; Zhang, Shuzhuo; Zheng, Jianquan; Wang, Liyun; Wei, Xiaoli

    2016-01-01

    The striatum is the most prominent nucleus in the basal ganglia and plays an important role in motor movement regulation. The cholinergic interneurons (ChIs) in striatum are involved in the motion regulation by releasing acetylcholine (ACh) and modulating the output of striatal projection neurons. Here, we report that muscarinic ACh receptor (M receptor) agonists, ACh and Oxotremorine (OXO-M), decreased the firing frequency of ChIs by blocking the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Scopolamine (SCO), a nonselective antagonist of M receptors, abolished the inhibition. OXO-M exerted its function by activating the Gi/o cAMP signaling cascade. The single-cell reverse transcription polymerase chain reaction (scRT-PCR) revealed that all the five subtypes of M receptors and four subtypes of HCN channels were expressed on ChIs. Among them, M2 receptors and HCN2 channels were the most dominant ones and expressed in every single studied cholinergic interneuron (ChI).Our results suggest that ACh regulates not only the output of striatal projection neurons, but also the firing activity of ChIs themselves by activating presynaptic M receptors in the dorsal striatum. The activation of M2 receptors and blockage of HCN2 channels may play an important role in ACh inhibition on the excitability of ChIs. This finding adds a new G-protein coupled receptor mediated regulation on ChIs and provides a cellular mechanism for control of cholinergic activity and ACh release in the dorsal striatum. PMID:27047336

  4. EXTENDED HCN AND HCO{sup +} EMISSION IN THE STARBURST GALAXY M82

    SciTech Connect

    Salas, P.; Galaz, G.; Salter, D.; Herrera-Camus, R.; Bolatto, A. D.; Kepley, A.

    2014-12-20

    We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO{sup +}, HNC, CS, and HC{sub 3}N lines, but here we focus on the HCN and HCO{sup +} emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO{sup +} observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO{sup +} J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 10{sup 6} M {sub ☉} and 21 × 10{sup 6} M {sub ☉}, or ≳ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is ≥0.3 M {sub ☉} yr{sup –1}, which would lower the starburst lifetime by ≥5%. The energy required to expel this mass of dense gas is (1-10) × 10{sup 52} erg.

  5. Kynurenic acid and zaprinast induce analgesia by modulating HCN channels through GPR35 activation.

    PubMed

    Resta, Francesco; Masi, Alessio; Sili, Maria; Laurino, Annunziatina; Moroni, Flavio; Mannaioni, Guido

    2016-09-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels have a key role in the control of cellular excitability. HCN2, a subgroup of the HCN family channels, are heavily expressed in small dorsal root ganglia (DRG) neurons and their activation seems to be important in the determination of pain intensity. Intracellular elevation of cAMP levels activates HCN-mediated current (Ih) and small DRG neurons excitability. GPR35, a Gi/o coupled receptor, is highly expressed in small DRG neurons, and we hypothesized that its activation, mediated by endogenous or exogenous ligands, could lead to pain control trough a reduction of Ih current. Patch clamp recordings were carried out in primary cultures of rat DRG neurons and the effects of GPR35 activation on Ih current and neuronal excitability were studied in control conditions and after adenylate cyclase activation with either forskolin or prostaglandin E2 (PGE2). We found that both kynurenic acid (KYNA) and zaprinast, the endogenous and synthetic GPR35 agonist respectively, were able to antagonize the forskolin-induced depolarization of resting membrane potential by reducing Ih-mediated depolarization. Similar results were obtained when PGE2 was used to activate adenylate cyclase and to increase Ih current and the overall neuronal excitability. Finally, we tested the analgesic effect of both GPR35 agonists in an in vivo model of PGE2-induced thermal hyperalgesia. In accord with the hypothesis, both KYNA and zaprinast showed a dose dependent analgesic effect. In conclusion, GPR35 activation leads to a reduced excitability of small DRG neurons in vitro and causes a dose-dependent analgesia in vivo. GPR35 agonists, by reducing adenylate cyclase activity and inhibiting Ih in DRG neurons may represent a promising new group of analgesic drugs. PMID:27131920

  6. Investigating the Spatial Structure of HCN Emission in Comet C/2012 F6 (Lemmon)

    NASA Astrophysics Data System (ADS)

    Booth, Shawn; Burkhardt, Andrew; Corby, Joanna; Dollhopf, Niklaus; Rawlings, Mark; Remijan, Anthony

    2015-11-01

    Comets are of particular interest in the field of Astrochemistry as they can be used as a direct probe of formation chemistry of the Solar System. Originating in the Oort Cloud reservoir, these long period objects experience relatively limited solar influence. The majority of cometary material (water, methane and ammonia ices) has remained in the same state as when it formed. These ices are precursors to more complex molecules which have been shown to form amino acids that are crucial for the development of life. HCN, or hydrogen cyanide, is of particular interest because it can form the nucleobase adenine (C5H5N5). The goals of this project are to map the HCN distribution of Comet C/2012 F6 (Lemmon) and to show the simultaneous observation capabilities of the Atacama Large Millimeter/Submillimeter Array (ALMA), which allows the extraction of 7-m array, 12-m array and single dish observation data. On UT 2013 May 11, Comet Lemmon was observed using ALMA. The Cycle 1 configuration was used with the Band 6 receivers, with a 1.5 GHz range centered on the HCN transition at 265.86 GHz, which gave a spectral resolution of 0.07 km/s. We show that Comet Lemmon has both a compact HCN region (found with the 12-m array) and also an extended component, forming a tail-like structure in the anti-motion direction (found with the 7-m array). We were also able to extract the autocorrelation data (single dish) and show that it is viable. This project was supported and funded by NRAO in conjunction with the National Science Foundation (NSF), with special thanks to the Astronomy Department at University of Virginia.

  7. Chemical evolution. XXI - The amino acids released on hydrolysis of HCN oligomers

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Wos, J. D.; Nooner, D. W.; Oro, J.

    1974-01-01

    Major amino acids released by hydrolysis of acidic and basic HCN oligomers are identified by chromatography as Gly, Asp, and diaminosuccinic acid. Smaller amounts of Ala, Ile and alpha-aminoisobutyric acid are also detected. The amino acids released did not change appreciably when the hydrolysis medium was changed from neutral to acidic or basic. The presence of both meso and d, l-diaminosuccinic acids was established by paper chromatography and on an amino acid analyzer.

  8. Lamellar {gamma}-AlOOH architectures: Synthesis and application for the removal of HCN

    SciTech Connect

    Hou Hongwei; Zhu You; Tang Gangling; Hu Qingyuan

    2012-06-15

    Using hexadecyl trimethyl ammonium bromide (CTAB) as a structure-directing agent and precipitator, the complete synthesis of lamellar {gamma}-AlOOH architectures was successfully accomplished via a hydrothermal route. Different product structures were obtained by varying the molar ratio of aluminum nitrate and CTAB. Several techniques, including X-ray powder diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry thermal analysis, were used to characterize the products. The effects of CTAB concentration, reaction temperature and time, and the molar ratio of Al{sup 3+}/CTAB on the product morphologies were investigated. The nitrogen adsorption and desorption measurements indicated that the {gamma}-AlOOH architectures possess a Brunauer-Emmett-Teller surface area of approximately 75.02 m{sup 2}/g. It was also demonstrated that 10 mg {gamma}-AlOOH architectures can remove 45.3% of the HCN (1.68 {mu}g/mL) from model wastewater. When 0.03 mg/cig {gamma}-AlOOH architectures were combined with cigarette paper, 8.12% of the present HCN was adsorbed. These results indicate that lamellar {gamma}-AlOOH architectures may be a potential adsorbent for removing HCN from highly toxic pollutant solutions and harmful cigarette smoke. Highlights: Black-Right-Pointing-Pointer Hexadecyl trimethyl ammonium bromide (CTAB) was used as a structure-directing agent and precipitator. Black-Right-Pointing-Pointer Hydrothermal treatment enables growth of lamellar {gamma}-AlOOH architectures. Black-Right-Pointing-Pointer Lamellar {gamma}-AlOOH architectures were demonstrated to exhibit high BET surface area and excellent adsorptive capacity. Black-Right-Pointing-Pointer HCN in contaminated water and cigarette smoke can be effectively removed by the prepared lamellar {gamma}-AlOOH superstructures.

  9. Environmental manipulations early in development alter seizure activity, Ih and HCN1 protein expression later in life.

    PubMed

    Schridde, Ulrich; Strauss, Ulf; Bräuer, Anja U; van Luijtelaar, Gilles

    2006-06-01

    Although absence epilepsy has a genetic origin, evidence from an animal model (Wistar Albino Glaxo/Rijswijk; WAG/Rij) suggests that seizures are sensitive to environmental manipulations. Here, we show that manipulations of the early rearing environment (neonatal handling, maternal deprivation) of WAG/Rij rats leads to a pronounced decrease in seizure activity later in life. Recent observations link seizure activity in WAG/Rij rats to the hyperpolarization-activated cation current (Ih) in the somatosensory cortex, the site of seizure generation. Therefore, we investigated whether the alterations in seizure activity between rats reared differently might be correlated with changes in Ih and its channel subunits hyperpolarization-activated cation channel HCN1, 2 and 4. Whole-cell recordings from layer 5 pyramidal neurons, in situ hybridization and Western blot of the somatosensory cortex revealed an increase in Ih and HCN1 in neonatal handled and maternal deprived, compared to control rats. The increase was specific to HCN1 protein expression and did not involve HCN2/4 protein expression, or mRNA expression of any of the subunits (HCN1, 2, 4). Our findings provide the first evidence that relatively mild changes in the neonatal environment have a long-term impact of absence seizures, Ih and HCN1, and suggest that an increase of Ih and HCN1 is associated with absence seizure reduction. Our findings shed new light on the role of Ih and HCN in brain functioning and development and demonstrate that genetically determined absence seizures are quite sensitive for early interventions. PMID:16820024

  10. TRIP8b regulates HCN1 channel trafficking and gating through two distinct C-terminal interaction sites

    PubMed Central

    Santoro, Bina; Hu, Lei; Liu, Haiying; Saponaro, Andrea; Pian, Phillip; Piskorowski, Rebecca A.; Moroni, Anna; Siegelbaum, Steven A.

    2011-01-01

    Hyperpolarization-activated cyclic nucleotide-regulated (HCN) channels in the brain associate with their auxiliary subunit TRIP8b (also known as PEX5R), a cytoplasmic protein expressed as a family of alternatively spliced isoforms. Recent in vitro and in vivo studies have shown that association of TRIP8b with HCN subunits both inhibits channel opening and alters channel membrane trafficking, with some splice variants increasing and others decreasing channel surface expression. Here, we address the structural bases of the regulatory interactions between mouse TRIP8b and HCN1. We find that HCN1 and TRIP8b interact at two distinct sites: an upstream site where the C-linker/cyclic nucleotide-binding domain of HCN1 interacts with an 80 amino acid domain in the conserved central core of TRIP8b, and a downstream site where the C-terminal -SNL tripeptide of the channel interacts with the tetratricopeptide repeat domain of TRIP8b. These two interaction sites play distinct functional roles in the effects of TRIP8b on HCN1 trafficking and gating. Binding at the upstream site is both necessary and sufficient for TRIP8b to inhibit channel opening. It is also sufficient to mediate the trafficking effects of those TRIP8b isoforms that downregulate channel surface expression, in combination with the trafficking motifs present in the N-terminal region of TRIP8b. In contrast, binding at the downstream interaction site serves to stabilize the C-terminal domain of TRIP8b, allowing for optimal interaction between HCN1 and TRIP8b as well as for proper assembly of the molecular complexes that mediate the effects of TRIP8b on HCN1 channel trafficking. PMID:21411649

  11. The interaction of He with vibrating HCN: potential energy surface, bound states, and rotationally inelastic cross sections.

    PubMed

    Denis-Alpizar, Otoniel; Stoecklin, Thierry; Halvick, Philippe; Dubernet, Marie-Lise

    2013-07-21

    A four-dimensional potential energy surface representing the interaction between He and hydrogen cyanide (HCN) subjected to bending vibrational motion is presented. Ab initio calculations were carried out at the coupled-cluster level with single and double excitations and a perturbative treatment of triple excitations, using a quadruple-zeta basis set and mid-bond functions. The global minimum is found in the linear He-HCN configuration with the H atom pointing towards helium at the intermolecular separation of 7.94 a0. The corresponding well depth is 30.35 cm(-1). First, the quality of the new potential has been tested by performing two comparisons with previous theoretical and experimental works. (i) The rovibrational energy levels of the He-HCN complex for a rigid linear configuration of the HCN molecule have been calculated. The dissociation energy is 8.99 cm(-1), which is slightly smaller than the semi-empirical value of 9.42 cm(-1). The transitions frequencies are found to be in good agreement with the experimental data. (ii) We performed close coupling calculations of the rotational de-excitation of rigid linear HCN in collision with He and observed a close similarity with the theoretical data published in a recent study. Second, the effects of the vibrational bending of HCN have been investigated, both for the bound levels of the He-HCN system and for the rotationally inelastic cross sections. This was performed with an approximate method using the average of the interaction potential over the vibrational bending wavefunction. While this improves slightly the comparison of calculated transitions frequencies with experiment, the cross sections remain very close to those obtained with rigid linear HCN. PMID:23883024

  12. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate firing of globus pallidus neurons in vivo.

    PubMed

    Chen, Lei; Xu, Rong; Sun, Feng-Jiao; Xue, Yan; Hao, Xiao-Meng; Liu, Hong-Xia; Wang, Hua; Chen, Xin-Yi; Liu, Zi-Ran; Deng, Wen-Shuai; Han, Xiao-Hua; Xie, Jun-Xia; Yung, Wing-Ho

    2015-09-01

    The globus pallidus plays a significant role in motor control under both health and pathological states. Recent studies have revealed that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels occupy a critical position in globus pallidus pacemaking activity. Morphological studies have shown the expression of HCN channels in the globus pallidus. To investigate the in vivo effects of HCN channels in the globus pallidus, extracellular recordings and behavioral tests were performed in the present study. In normal rats, micro-pressure ejection of 0.05mM ZD7288, the selective HCN channel blocker, decreased the frequency of spontaneous firing in 21 out of the 40 pallidal neurons. The average decrease was 50.4±5.4%. Interestingly, in another 18 out of the 40 pallidal neurons, ZD7288 increased the firing rate by 137.1±27.6%. Similar bidirectional modulation on the firing rate was observed by a higher concentration of ZD7288 (0.5mM) as well as another HCN channel blocker, CsCl. Furthermore, activation of HCN channels by 8-Br-cAMP increased the firing rate by 63.0±9.3% in 15 out of the 25 pallidal neurons and decreased the firing rate by 46.9±9.4% in another 8 out of the 25 pallidal neurons. Further experiments revealed that modulation of glutamatergic but not GABAergic transmission may be involved in ZD7288-induced increase in firing rate. Consistent with electrophysiological results, further studies revealed that modulation of HCN channels also had bidirectional effects on behavior. Taken together, the present studies suggest that HCN channels may modulate the activity of pallidal neurons by different pathways in vivo. PMID:25858108

  13. Detection of HCN and C2H2 in ISO Spectra of Oxygen-Rich AGB Stars

    NASA Technical Reports Server (NTRS)

    Carbon, Duane F.; Chiar, Jean; Goorvitch, David; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Cool oxygen-rich AGB stars were not expected to have organic molecules like HCN in either their photospheres or circumstellar envelopes (CSEs). The discovery of HCN and CS microwave emission from the shallowest CSE layers of these stars was a considerable surprise and much theoretical effort has been expended in explaining the presence of such organics. To further explore this problem, we have undertaken a systematic search of oxygen-rich AGB stellar spectra in the Infrared Space Observatory (ISO) data archive. Our purposes are to find evidence regarding critical molecular species that could be of value in choosing among the proposed theoretical models, to locate spectral features which might give clues to conditions deeper in the CSEs, and to lay the groundwork for future SIRTF (Space Infrared Telescope Facility) and SOFIA (Stratospheric Observatory for Infrared Astronomy) observations. Using carefully reduced observations, we have detected weak absorption features arising from HCN and possibly C2H2 in a small number of oxygen-rich AGB stars. The most compelling case is NML Cyg which shows both HCN (14 microns) and CO2 (15 microns). VY CMa, a similar star, shows evidence for HCN, but not CO2. Two S-type stars show evidence for the C-H bending transitions: W Aql at 14 microns (HCN) and both W Aql and S Cas at 13.7 microns (C2H2). Both W Aql and S Cas as well as S Lyr, a SC-type star, show 3 micron absorption which may arise from the C-H stretch of HCN and C2H2. In the case of NML Cyg, we show that the HCN and CO2 spectral features are formed in the CSE at temperatures well above those of the outermost CSE layers and derive approximate column densities. In the case of the S-stars, we discuss the evidence for the organic features and their photospheric origin.

  14. Investigation of the spin-lattice relaxation of 13CO and 13CO2 adsorbed in the metal-organic frameworks Cu3(btc)2 and Cu3-xZnx(btc)2

    NASA Astrophysics Data System (ADS)

    Gul-E-Noor, Farhana; Michel, Dieter; Krautscheid, Harald; Haase, Jürgen; Bertmer, Marko

    2013-07-01

    The 13C nuclear spin-lattice relaxation time of 13CO and 13CO2 molecules adsorbed in the metal-organic frameworks (MOFs) Cu2.97Zn0.03(btc)2 and Cu3(btc)2 is investigated over a wide range of temperatures at resonance frequencies of 75.468 and 188.62 MHz. In all cases a mono-exponential relaxation is observed, and the 13C spin-lattice relaxation times (T1) reveal minima within the temperature range of the measurements and both frequencies. This allows us to carry out a more detailed analysis of the 13C spin relaxation data and to consider the influence due to the spectral functions of the thermal motion. In a model-free discussion of the temperature dependence of the ratios T1 (T)/T1,min we observe a motional mechanism that can be described by a single correlation time. In relation to the discussion of the relaxation mechanisms this can be understood in terms of dominating translational motion with mean jump distance being larger than the minimum distances between neighboring adsorption sites in the MOFs. A more detailed discussion of the jump-like motion observed here might be carried out on the basis of self-diffusion coefficients. From the present spin relaxation measurements activation energies for the local motion of the adsorbed molecules in the MOFs can be estimated to be 3.3 kJ/mol and 2.2 kJ/mol, for CO and CO2 molecules, respectively. Finally, our findings are compared with our recent results derived from the 13C line shape analysis.

  15. The structure and energetics of the HCN-HNC transition state

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Rendell, Alistair P.

    1991-01-01

    The optimum geometries and quadratic force constants of HCN, HNC and the transition state connecting them have been determined at the single- and double-excitation coupled-cluster (CCSD) and CCSD(T) levels of theory. Energy differences were evaluated using the CCSD and CCSD(T) methods in conjunction with large atomic natural orbital basis sets containing g-type basis functions on the heavy atoms and f-type functions on hydrogen. The most reliable structure obtained for the transition state has bond distances of 1.194, 1.188, and 1.389 A for r(CN), r(CH), and r(NH), respectively. Including a correction for zero-point vibrational energies, the transition state is predicted to be 44.6 + or - 1.0 kcal/mol above the HCN isomer, while HNC is predicted to be 14.4 + or - 1.0 kcal/mol above HCN. The latter value is in excellent agreement with the most recent experimental determination (14.8 + or - 2.0 kcal/mol).

  16. HCN2 ion channels: basic science opens up possibilities for therapeutic intervention in neuropathic pain.

    PubMed

    Tsantoulas, Christoforos; Mooney, Elizabeth R; McNaughton, Peter A

    2016-09-15

    Nociception - the ability to detect painful stimuli - is an invaluable sense that warns against present or imminent damage. In patients with chronic pain, however, this warning signal persists in the absence of any genuine threat and affects all aspects of everyday life. Neuropathic pain, a form of chronic pain caused by damage to sensory nerves themselves, is dishearteningly refractory to drugs that may work in other types of pain and is a major unmet medical need begging for novel analgesics. Hyperpolarisation-activated cyclic nucleotide (HCN)-modulated ion channels are best known for their fundamental pacemaker role in the heart; here, we review data demonstrating that the HCN2 isoform acts in an analogous way as a 'pacemaker for pain', in that its activity in nociceptive neurons is critical for the maintenance of electrical activity and for the sensation of chronic pain in pathological pain states. Pharmacological block or genetic deletion of HCN2 in sensory neurons provides robust pain relief in a variety of animal models of inflammatory and neuropathic pain, without any effect on normal sensation of acute pain. We discuss the implications of these findings for our understanding of neuropathic pain pathogenesis, and we outline possible future opportunities for the development of efficacious and safe pharmacotherapies in a range of chronic pain syndromes. PMID:27621481

  17. HCN, Formamidic Acid, and Formamide in Aqueous Solution: A Free-Energy Map.

    PubMed

    Kua, Jeremy; Thrush, Kyra L

    2016-08-25

    What chemical species might be found if water or ammonia reacts with HCN in aqueous solution under neutral conditions? Is it energetically favorable for formamidic acid, the first hydration product of HCN, to tautomerize into formamide under standard conditions? Do these molecules form stable oligomers in solution? To answer these questions, we constructed a Gibbs free-energy map of the molecules that might be present to evaluate their relative thermodynamic and kinetic stability. Our protocol utilizes density functional theory calculations, Poisson-Boltzmann implicit solvent, and thermodynamic corrections. We find that for C1 species, formamide is indeed the thermodynamic sink, although the initial barrier to hydration is ∼30 kcal/mol. Molecules with one carbon and three heteroatoms are less stable. We also find that for HCN trimerization, although the planar sp(2) six-membered ring is more stable compared to its monomers, the reverse is true for the nonplanar sp(3) six-membered rings formed by trimerization of formamidic acid or formamide. PMID:27016454

  18. United States Historical Climatology Network (US HCN) monthly temperature and precipitation data

    SciTech Connect

    Daniels, R.C.; Boden, T.A.; Easterling, D.R.; Karl, T.R.; Mason, E.H.; Hughes, P.Y.; Bowman, D.P.

    1996-01-11

    This document describes a database containing monthly temperature and precipitation data for 1221 stations in the contiguous United States. This network of stations, known as the United States Historical Climatology Network (US HCN), and the resulting database were compiled by the National Climatic Data Center, Asheville, North Carolina. These data represent the best available data from the United States for analyzing long-term climate trends on a regional scale. The data for most stations extend through December 31, 1994, and a majority of the station records are serially complete for at least 80 years. Unlike many data sets that have been used in past climate studies, these data have been adjusted to remove biases introduced by station moves, instrument changes, time-of-observation differences, and urbanization effects. These monthly data are available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center. The NDP includes this document and 27 machine-readable data files consisting of supporting data files, a descriptive file, and computer access codes. This document describes how the stations in the US HCN were selected and how the data were processed, defines limitations and restrictions of the data, describes the format and contents of the magnetic media, and provides reprints of literature that discuss the editing and adjustment techniques used in the US HCN.

  19. Diode laser absorption measurement and analysis of HCN in atmospheric-pressure, fuel-rich premixed methane/air flames

    SciTech Connect

    Gersen, S.; Mokhov, A.V.; Levinsky, H.B.

    2008-10-15

    Measurements of HCN in flat, fuel-rich premixed methane/air flames at atmospheric pressure are reported. Quartz-microprobe sampling followed by wavelength modulation absorption spectroscopy with second harmonic detection was used to obtain an overall measurement uncertainty of better than 20% for mole fractions HCN on the order of 10 ppm. The equivalence ratio, {phi}, was varied between 1.3 and 1.5, while the flame temperature was varied independently by changing the mass flux through the burner surface at constant equivalence ratio. Under the conditions of the experiments, the peak mole fractions vary little, in the range of 10-15 ppm. Increasing the flame temperature by increasing the mass flux had little influence on the peak mole fraction, but accelerated HCN burnout substantially. At high equivalence ratio and low flame temperature, HCN burnout is very slow: at {phi}=1.5, {proportional_to}10ppm HCN is still present 7 mm above the burner surface. Substantial quantitative disagreement is observed between the experimental profiles and those obtained from calculations using GRI-Mech 3.0, with the calculations generally overpredicting the results significantly. Changing the rates of key formation and consumption reactions for HCN can improve the agreement, but only by making unreasonable changes in these rates. Inclusion of reactions describing NCN formation and consumption in the calculations improves the agreement with the measurements considerably. (author)

  20. Resonance assignment of the ligand-free cyclic nucleotide-binding domain from the murine ion channel HCN2.

    PubMed

    Börger, Claudia; Schünke, Sven; Lecher, Justin; Stoldt, Matthias; Winkhaus, Friederike; Kaupp, U Benjamin; Willbold, Dieter

    2015-10-01

    Hyperpolarization activated and cyclic nucleotide-gated (HCN) ion channels as well as cyclic nucleotide-gated (CNG) ion channels are essential for the regulation of cardiac cells, neuronal excitability, and signaling in sensory cells. Both classes are composed of four subunits. Each subunit comprises a transmembrane region, intracellular N- and C-termini, and a C-terminal cyclic nucleotide-binding domain (CNBD). Binding of cyclic nucleotides to the CNBD promotes opening of both CNG and HCN channels. In case of CNG channels, binding of cyclic nucleotides to the CNBD is sufficient to open the channel. In contrast, HCN channels open upon membrane hyperpolarization and their activity is modulated by binding of cyclic nucleotides shifting the activation potential to more positive values. Although several high-resolution structures of CNBDs from HCN and CNG channels are available, the gating mechanism for murine HCN2 channel, which leads to the opening of the channel pore, is still poorly understood. As part of a structural investigation, here, we report the complete backbone and side chain resonance assignments of the murine HCN2 CNBD with part of the C-linker. PMID:25324217

  1. Vibration-Rotation Analysis of the 13CO_2 Asymmetric Stretch Fundamental Band in Ambient Air for the Physical Chemistry Teaching Laboratory

    NASA Astrophysics Data System (ADS)

    Dolson, David A.; Anders, Catherine B.

    2015-06-01

    The CO_2 asymmetric stretch fundamental band near 4.3 μm is one of the strongest infrared absorption transitions of all small molecules. This band is an undesired interference in most infrared spectra, but it also serves as a potential choice for a vibration-rotation analysis experiment in the physical chemistry teaching laboratory. Due to the strength of this band and the 1.1% natural abundance of carbon-13, the asymmetric stretch fundamental band of 13CO_2 is readily observable in a typical ambient air background spectrum and is shifted sufficiently from the stronger 12CO_2 fundamental such that the 13CO_2 P-branch lines are almost completely free of interferences and are easily assigned. All of the 13CO_2 R-branch lines appear within the 12CO_2 P-branch, which creates assignment challenges. Students in our program have analyzed the 13CO_2 fundamental asymmetric stretch band over a two-year period. Analyses of the P-branch line positions enabled the prediction of additional R-branch line positions, which guided line identification and measurements in the 13CO_2 R-branch. C=O bond lengths determined from analyses of the 13CO_2 spectra improved when R-branch lines were added to the initial P-branch data sets. Spectral appearance, analyses and results will be presented for spectra obtained at 0.5 cm-1 resolution and at 0.125 cm-1 resolution. The challenge of predicting and finding the 13CO_2 R-branch lines among other interfering lines adds an element of realism to this experiment that is not found in many student experiments of this type.

  2. 12CO And 13CO Observations Toward The Extraordinary Filament In The Orion-monoceros Molecular Cloud Complex

    NASA Astrophysics Data System (ADS)

    Lee, Jeewon; Kim, S. S.; Morris, M.; Kim, S.; Sohn, B.

    2009-01-01

    We have observed the Northern filament in the Orion-Monoceros molecular cloud complex (OMC) in the J=1-0 lines of 12CO and 13CO using SRAO 6-m telescope. We have mapped three regions of the Northern filament with a spatial resolution of 2 arcmin. This filament is very narrow ( 0.5o) and significantly extended ( 10o) on the sky. The shape and motion of this extraordinary filament suggest the influence of a magnetic field that is highly ordered on a large scale, and the filament appears to connect molecular clouds lying far below the galactic plane to the plane itself. We seek the evidence for flow along the filament, as well as for acceleration and rotation. The primary question we seek to answer is whether the filament is a channel along which molecular gas moves toward the Galactic plane from the OMC region.

  3. Precipitation Kinetics of M2C Carbide in Severely Ausformed 13Co-8Ni Secondary Hardening Steels

    NASA Astrophysics Data System (ADS)

    Cho, Ki Sub; Park, Sung Soo; Kim, Hong Kyu; Song, Young Beum; Kwon, Hoon

    2015-04-01

    With continuous heating calorimetric data as a basis, the kinetics of M2C formation during isothermal aging was modeled in severely ausformed 13Co-8Ni steels using the Johnson-Mehl-Avrami theory coupled with a variation of effective activation energy with respect to the degree of transformation. These results were compared with small-angle neutron scattering measurements and discussed in terms of variations in the thermodynamic and kinetic behavior of M2C precipitation. In particular, the M2C carbides in the deformed samples contained more Fe content compared with the non-deformed samples. As this can be ascribed to the ausforming effect increasing the driving force for M2C nucleation, it consequently leads to the decrease of the growth/coarsening rate for M2C carbides at over-aged conditions.

  4. 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

  5. Airborne measurements of HCN, CO2 and CH4 associated with emissions from boreal biomass burning

    NASA Astrophysics Data System (ADS)

    Muller, J. B. A.; Le Breton, M.; O'Shea, S.; Bauguitte, S.; Gallagher, M. W.; Bacak, A.; Percival, C. J.

    2012-04-01

    High resolution measurements of hydrogen cyanide (HCN), carbon dioxide (CO2) and methane (CH4) were made over Canada onboard the UK Atmospheric Research Aircraft FAAM BAe-146 from 12 July to 4 August 2011. The observations were made as part of the international BORTAS project which aims to quantify the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites. The sorties were aimed at transecting and sampling the outflow from the commonly occurring North American boreal forest fires during the summer months and to investigate and identify the chemical composition and evolution of these plumes. HCN is a distinctive and useful marker for forest fire emissions and it was detected using chemical ionisation mass spectrometry (CIMS). The ionisation scheme employed I- ions which form an adduct with HCN and typical sensitivities of 0.6 counts/ppt have been achieved for sampling at 1 Hz. Elevated CO2 and CH4 are also commonly associated with forest fire emissions and they were measured using the Fast Greenhouse Gas Analyser (FGGA) by Los Gatos Research. This near-IR off-axis integrated cavity output spectroscopy system allowed detection and sampling at 10 Hz. In-flight calibrations revealed a mean accuracy of -0.02 ppmv ± 0.57 ppmv (1σ precision) for CO2 and a mean accuracy of 0.08 ppbv ± 2.31 ppbv (1σ precision) for CH4 for 1Hz observations during the BORTAS campaign. During the 10 flights over the Eastern Canada region (Nova Scotia, New Brunswick, Newfoundland, Ontario and Quebec) several biomass burning plumes were sampled and enhancements in levels of HCN, CO2 and CH4 within these plumes were evident. The observed HCN enhancements inside the plume compared to outside the plume reached up to factor of about 10. For the majority of plumes, a good positive correlation with CO was seen, and in some plumes, CO was observed whilst no HCN was detected, indicating possibly emission sources of anthropogenic activity rather than

  6. Ro-vibrational excitation of an organic molecule (HCN) in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Bruderer, Simon; Harsono, Daniel; van Dishoeck, Ewine F.

    2015-03-01

    Context. Organic molecules are important constituents of protoplanetary disks. Their ro-vibrational lines observed in the near- and mid-infrared are commonly detected toward T Tauri disks. These lines are the only way to probe the chemistry in the inner few au where terrestrial planets form. To understand this chemistry, accurate molecular abundances have to be determined. This is complicated by excitation effects that include radiative pumping. Most analyses so far have made the assumption of local thermal equilibrium (LTE), which may not be fulfilled because of the high gas densities required to collisionally thermalize the vibrational levels of the molecules. Aims: The non-LTE excitation effects of hydrogen cyanide (HCN) are studied to evaluate (i) how the abundance determination is affected by the LTE assumption; (ii) whether the ro-vibrational excitation is dominated by collisions or radiative pumping; and (iii) which regions of protoplanetary disks are traced by certain vibrational bands. Methods: Starting from estimates for the collisional rate coefficients of HCN, non-LTE slab models of the HCN emission were calculated to study the importance of different excitation mechanisms. Using a new radiative transfer model, the HCN emission from a full two-dimensional disk was then modeled to study the effect of the non-LTE excitation, together with the line formation. We ran models tailored to the T Tauri disk AS 205 (N) where HCN lines in both the 3 μm and 14 μm bands have been observed by VLT-CRIRES and the Spitzer Space Telescope. Results: Reproducing the observed 3 μm/14 μm flux ratios requires very high densities and kinetic temperatures (n> 1014 cm-3 and T> 750 K), if only collisional excitation is accounted for. Radiative pumping can, however, excite the lines easily out to considerable radii ~10 au. Consequently, abundances derived from LTE and non-LTE models do not differ by more than a factor of about 3. Models with both a strongly enhanced abundance

  7. Unraveling carbohydrate transport mechanisms in young beech trees (Fagus sylvatica f. purpurea) by 13CO2 efflux measurements from stem and soil

    NASA Astrophysics Data System (ADS)

    Thoms, Ronny; Muhr, Jan; Keitel, Claudia; Kayler, Zachary; Gavrichkova, Olga; Köhler, Michael; Gessler, Arthur; Gleixner, Gerd

    2016-04-01

    Transport mechanisms of soluble carbohydrates and diurnal CO2 efflux from tree stems and surrounding soil are well studied. However, the effect of transport carbohydrates on respiration and their interaction with storage processes is largely unknown. Therefore, we performed a set of 13CO2 pulse labeling experiments on young trees of European beech (Fagus sylvatica f. purpurea). We labeled the whole tree crowns in a closed transparent plastic chamber with 99% 13CO2 for 30 min. In one experiment, only a single branch was labeled and removed 36 hours after labeling. In all experiments, we continuously measured the 13CO2 efflux from stem, branch and soil and sampled leaf and stem material every 3 h for 2 days, followed by a daily sampling of leaves in the successive 5 days. The compound specific δ 13C value of extracted soluble carbohydrates from leaf and stem material was measured by high-performance liquid chromatography linked with an isotope ratio mass spectrometer (HPLC-IRMS). The 13CO2 signal from soil respiration occurred only few hours after labeling indicating a very high transport rate of carbohydrates from leaf to roots and to the rhizosphere. The label was continuously depleted within the next 5 days. In contrast, we observed a remarkable oscillating pattern of 13CO2 efflux from the stem with maximum 13CO2 enrichment at noon and minima at night time. This oscillation suggests that enriched carbohydrates are respired during the day, whereas in the night the enriched sugars are not respired. The observed oscillation in stem 13CO2 enrichment remained unchanged even when only single branches were labelled and cut right afterwards. Thus, storage and conversion of carbohydrates only occurred within the stem. The δ13C patterns of extracted soluble carbohydrates showed, that a transformation of transitory starch to carbohydrates and vice versa was no driver of the oscillating 13CO2 efflux from the stem. Carbohydrates might have been transported in the phloem to

  8. The Variability of HCN in Titan’s Upper Atmosphere as Implied by the Cassini Ion-Neutral Mass Spectrometer Measurements

    NASA Astrophysics Data System (ADS)

    Cui, J.; Cao, Y.-T.; Lavvas, P. P.; Koskinen, T. T.

    2016-07-01

    HCN is an important constituent in Titan’s upper atmosphere, serving as the main coolant in the local energy budget. In this study, we derive the HCN abundance at the altitude range of 960–1400 km, combining the Ion-Neutral Mass Spectrometer data acquired during a large number of Cassini flybys with Titan. Typically, the HCN abundance declines modestly with increasing altitude and flattens to a near constant level above 1200 km. The data reveal a tendency for dayside depletion of HCN, which is clearly visible below 1000 km but weakens with increasing altitude. Despite the absence of convincing anti-correlation between HCN volume mixing ratio and neutral temperature, we argue that the variability in HCN abundance makes an important contribution to the large temperature variability observed in Titan’s upper atmosphere.

  9. HCN channels enhance spike phase coherence and regulate the phase of spikes and LFPs in the theta-frequency range.

    PubMed

    Sinha, Manisha; Narayanan, Rishikesh

    2015-04-28

    What are the implications for the existence of subthreshold ion channels, their localization profiles, and plasticity on local field potentials (LFPs)? Here, we assessed the role of hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels in altering hippocampal theta-frequency LFPs and the associated spike phase. We presented spatiotemporally randomized, balanced theta-modulated excitatory and inhibitory inputs to somatically aligned, morphologically realistic pyramidal neuron models spread across a cylindrical neuropil. We computed LFPs from seven electrode sites and found that the insertion of an experimentally constrained HCN-conductance gradient into these neurons introduced a location-dependent lead in the LFP phase without significantly altering its amplitude. Further, neurons fired action potentials at a specific theta phase of the LFP, and the insertion of HCN channels introduced large lags in this spike phase and a striking enhancement in neuronal spike-phase coherence. Importantly, graded changes in either HCN conductance or its half-maximal activation voltage resulted in graded changes in LFP and spike phases. Our conclusions on the impact of HCN channels on LFPs and spike phase were invariant to changes in neuropil size, to morphological heterogeneity, to excitatory or inhibitory synaptic scaling, and to shifts in the onset phase of inhibitory inputs. Finally, we selectively abolished the inductive lead in the impedance phase introduced by HCN channels without altering neuronal excitability and found that this inductive phase lead contributed significantly to changes in LFP and spike phase. Our results uncover specific roles for HCN channels and their plasticity in phase-coding schemas and in the formation and dynamic reconfiguration of neuronal cell assemblies. PMID:25870302

  10. ALMA Investigation of Vibrationally Excited HCN/HCO+/HNC Emission Lines in the AGN-Hosting Ultraluminous Infrared Galaxy IRAS 20551‑4250

    NASA Astrophysics Data System (ADS)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma

    2016-07-01

    We present the results of ALMA Cycle 2 observations of the ultraluminous infrared galaxy IRAS 20551‑4250 at HCN/HCO+/HNC J = 3–2 lines at both vibrational ground (v = 0) and vibrationally excited (v 2 = 1) levels. This galaxy contains a luminous buried active galactic nucleus (AGN), in addition to starburst activity, and our ALMA Cycle 0 data revealed a tentatively detected vibrationally excited HCN v 2 = 1f J = 4–3 emission line. In our ALMA Cycle 2 data, the HCN/HCO+/HNC J = 3–2 emission lines at v = 0 are clearly detected. The HCN and HNC v 2 = 1f J = 3–2 emission lines are also detected, but the HCO+ v 2 = 1f J = 3–2 emission line is not. Given the high energy level of v 2 = 1 and the resulting difficulty of collisional excitation, we compared these results with those of the calculation of infrared radiative pumping, using the available infrared 5–35 μm spectrum. We found that all of the observational results were reproduced if the HCN abundance was significantly higher than that of HCO+ and HNC. The flux ratio and excitation temperature between v 2 = 1f and v = 0, after correction for possible line opacity, suggests that infrared radiative pumping affects rotational (J-level) excitation at v = 0 at least for HCN and HNC. The HCN-to-HCO+ v = 0 flux ratio is higher than those of starburst-dominated regions, and will increase even more when the derived high HCN opacity is corrected. The enhanced HCN-to-HCO+ flux ratio in this AGN-hosting galaxy can be explained by the high HCN-to-HCO+ abundance ratio and sufficient HCN excitation at up to J = 4, rather than the significantly higher efficiency of infrared radiative pumping for HCN than HCO+.

  11. Recent development of LiNi1/3Co1/3Mn1/3O2 as cathode material of lithium ion battery.

    PubMed

    Zhu, Ji-Ping; Xu, Quan-Bao; Yang, Hong-Wei; Zhao, Jun-Jie; Yang, Guang

    2011-12-01

    Layered LiNi1/3Co1/3Mn1/3O2, owing to its excellent electrochemical properties, has been used as cathode material for lithium-ion batteries, especially for hybrid electric vehicles. It has many merits such as high capacity, long cycle life, low cost and little harm to environment. Therefore, LiNi1/3Co1/3Mn1/3O2 has become a great concern by scholars on energy and material fields. However, the electronic conductivity and the charge-discharge capacity at high current should be enhanced before any materials modifications. Here, this paper summarizes the main synthetic technologies of LiNi1/3Co1/3Mn1/3O2 in recent years, including synthesis methods, doping, surface coating modification, and the future development trends discussed. PMID:22408910

  12. Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

    NASA Astrophysics Data System (ADS)

    Bhowmik, Ayan; Dolbnya, Igor P.; Britton, T. Ben; Jones, Nicholas G.; Sernicola, Giorgio; Walter, Claudia; Gille, Peter; Dye, David; Clegg, William J.; Giuliani, Finn

    2016-03-01

    In this study, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to investigate the evolution of deformation in Al13Co4. Streaking of the Laue spots shows that the onset of plastic flow occurs at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enable the geometrically necessary dislocation density to be estimated as 1.1 × 1013 m-2.

  13. Multivariate determination of 13CO2/12CO2 ratios in exhaled mouse breath with mid-infrared hollow waveguide gas sensors.

    PubMed

    Seichter, Felicia; Wilk, Andreas; Wörle, Katharina; Kim, Seong-Soo; Vogt, Josef A; Wachter, Ulrich; Radermacher, Peter; Mizaikoff, Boris

    2013-05-01

    The (12)CO2/(13)CO2 isotope ratio is a well-known marker in breath for a variety of biochemical processes and enables monitoring, e.g., of the glucose metabolism during sepsis. Using animal models-here, at a mouse intensive care unit-the simultaneous determination of (12)CO2 and (13)CO2 within small volumes of mouse breath was enabled by coupling a novel low-volume hollow waveguide gas cell to a compact Fourier transform infrared spectrometer combined with multivariate data evaluation based on partial least squares regression along with optimized data preprocessing routines. PMID:23503745

  14. Evaluating the Community Land Model in a pine stand with shading manipulations and 13CO2 labeling

    DOE PAGESBeta

    Mao, Jiafu; Ricciuto, Daniel M.; Thornton, Peter E.; Warren, Jeffrey M.; King, Anthony Wayne; Shi, Xiaoying; Iversen, Colleen M.; Norby, Richard J.

    2016-02-03

    Carbon partitioning and flow through ecosystems regulates land surface atmosphere CO2 exchange and thus is a key, albeit uncertain component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked C partitioning through a young Pinus taeda stand following pulse-labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon partitioning and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbonmore » and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. To constrain CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with the pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was better able to simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3-week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15-95 cm depth, transpiration, relative change in stem carbon, and soil CO2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO2 label from the atmosphere through foliage, phloem, roots or surface soil CO2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4

  15. Evaluating the Community Land Model in a pine stand with 13CO2 labeling and shading manipulations

    DOE PAGESBeta

    Mao, Jiafu; Ricciuto, Daniel M; Thornton, Peter E; Warren, Jeffrey M.; King, Anthony Wayne; Shi, Xiaoying; Iversen, Colleen M; Norby, Richard J

    2016-01-01

    Carbon partitioning and flow through ecosystems regulates land surface atmosphere CO2 exchange and thus is a key, albeit uncertain component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked C partitioning through a young Pinus taeda stand following pulse-labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon partitioning and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbonmore » and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. To constrain CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with the pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was better able to simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3-week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15-95 cm depth, transpiration, relative change in stem carbon, and soil CO2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO2 label from the atmosphere through foliage, phloem, roots or surface soil CO2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4

  16. Evaluating the Community Land Model in a pine stand with 13CO2 labeling and shading manipulations

    SciTech Connect

    Mao, Jiafu; Ricciuto, Daniel M; Thornton, Peter E; Warren, Jeffrey M.; King, Anthony Wayne; Shi, Xiaoying; Iversen, Colleen M; Norby, Richard J

    2016-01-01

    Carbon partitioning and flow through ecosystems regulates land surface atmosphere CO2 exchange and thus is a key, albeit uncertain component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked C partitioning through a young Pinus taeda stand following pulse-labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon partitioning and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbon and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. To constrain CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with the pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was better able to simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3-week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15-95 cm depth, transpiration, relative change in stem carbon, and soil CO2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO2 label from the atmosphere through foliage, phloem, roots or surface soil CO2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4. Overall

  17. Seasonal variations of belowground carbon transfer assessed by in situ 13CO2 pulse labelling of trees

    NASA Astrophysics Data System (ADS)

    Epron, D.; Ngao, J.; Dannoura, M.; Bakker, M. R.; Zeller, B.; Bazot, S.; Bosc, A.; Plain, C.; Lata, J. C.; Priault, P.; Barthes, L.; Loustau, D.

    2011-05-01

    Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objective of our study was to assess patterns of belowground carbon allocation among tree species and along seasons. Pure 13CO2 pulse labelling of the entire crown of three different tree species (beech, oak and pine) was carried out at distinct phenological stages. Excess 13C in soil CO2 efflux was tracked using tuneable diode laser absorption spectrometry to determine time lags between the start of the labelling and the appearance of 13C in soil CO2 efflux and the amount of 13C allocated to soil CO2 efflux. Isotope composition (δ13C) of CO2 respired by fine roots and soil microbes was measured at several occasions after labelling, together with δ13C of bulk root tissue and microbial carbon. Time lags ranged from 0.5 to 1.3 days in beech and oak and were longer in pine (1.6-2.7 days during the active growing season, more than 4 days during the resting season), and the transfer of C to the microbial biomass was as fast as to the fine roots. The amount of 13C allocated to soil CO2 efflux was estimated from a compartment model. It varied between 1 and 21 % of the amount of 13CO2 taken up by the crown, depending on the species and the season. While rainfall exclusion that moderately decreased soil water content did not affect the pattern of carbon allocation to soil CO2 efflux in beech, seasonal patterns of carbon allocation belowground differed markedly between species, with pronounced seasonal variations in pine and beech. In beech, it may reflect competition with the strength of other sinks (aboveground growth in late spring and storage in late summer) that were not observed in oak. We report a fast transfer of recent photosynthates to the mycorhizosphere and we conclude that the patterns of carbon

  18. Evaluating the Community Land Model in a pine stand with 13CO2 labeling and shading manipulations

    NASA Astrophysics Data System (ADS)

    Mao, J.; Ricciuto, D. M.; Thornton, P. E.; Warren, J. M.; King, A. W.; Shi, X.; Iversen, C. M.; Norby, R. J.

    2015-05-01

    Carbon allocation and flow through ecosystems regulate land surface-atmosphere CO2 exchange and thus is a key, albeit uncertain, component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked carbon allocation through a young Pinus taeda stand following pulse-labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon allocation and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbon and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. For CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was able to better simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3 week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15-95 cm depth, transpiration, relative change in stem carbon, and soil CO2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO2 label from the atmosphere through foliage, phloem, roots or surface soil CO2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4. Overall, these types

  19. HCN oxidation in an O{sub 2}/CO{sub 2} atmosphere: An experimental and kinetic modeling study

    SciTech Connect

    Gimenez-Lopez, J.; Millera, A.; Bilbao, R.; Alzueta, M.U.

    2010-02-15

    HCN is one of the most important intermediates in NO{sub x} chemistry including formation and removal processes and the knowledge of HCN oxidation is thus very important to minimize NO{sub x} emissions. The present work aims to evaluate the oxidation behavior of HCN in an O{sub 2}/CO{sub 2} atmosphere, due to the lack of studies at these specific operating conditions and the increasing importance of the oxy-fuel combustion processes, characterized by an O{sub 2}/CO{sub 2} combustion atmosphere instead of air. With this purpose, a flow reactor experimental and kinetic modeling study of the oxidation of HCN under CO{sub 2} diluted conditions, in the 900-1450 K temperature range and for different stoichiometries, ranging from very reducing to oxidizing conditions, has been performed. The large experimental differences observed in the O{sub 2}/CO{sub 2} atmosphere in comparison to traditional air-fired combustion corroborate the importance of the HCN oxidation study in an O{sub 2}/CO{sub 2} environment. The presence of high CO{sub 2} concentration levels clearly inhibits HCN oxidation, since CO{sub 2} competes with O{sub 2} for atomic hydrogen through the CO{sub 2} + H {r_reversible} CO + OH reaction. The experimental results show the oxidation regime of HCN for different stoichiometries, analyzing the formation of the main products of the process: CO, NO, N{sub 2}, N{sub 2}O and HNCO. The higher availability of oxygen increases the HCN conversion, even though the onset temperature for reaction is almost similar at any stoichiometry studied. The mechanism used for calculations was that developed by Dagaut et al. [P. Dagaut, P. Glarborg, M.U. Alzueta, Prog. Energy Combust. Sci. 34 (2008) 1-46] for the oxidation of HCN in air combustion, updated in the present work to take into account the presence of an O{sub 2}/CO{sub 2} combustion atmosphere. In general, the modified model gives a reasonably good description of the experiments performed. (author)

  20. Mass Losses Of Co, Cs And Hcn On Jupiter/sl9

    NASA Astrophysics Data System (ADS)

    Moreno, Raphael; Marten, A.

    2006-09-01

    Since comet Shoemaker-Levy 9 (SL9) collided with Jupiter in 1994, the IRAM 30-m Telescope (Pico Veleta, Spain) and the 15-m JCMT (Mauna Kea,Hawaii) have regularly observed Jupiter at millimeter/submillimeter wavelengths. Molecular trace species such as HCN, CO, CS and their isotopomers have been detected in the upper atmosphere since the collision. Because of the high spectral resolution attained, our data allow one to infer both temperature and abundances in Jupiter's stratosphere with a maximum spatial resolution of 10 arcsec. We have used all these data to monitor the latitudinal spreading since the impacts occurred (Marten et al. 1995), to look for changes in their abundances with time (Moreno et al. 2001, 2003) and to determine several isotopic ratios (Matthews et al. 2002). Data taken in 2004 have shown that latitudinal distributions of all these species were almost homogeneous 10 years after impacts, as predicted by Moreno et al. 2003. Moreover, compared to 1998 results, respective mass loss factors as high as 2-7 have been determined for the three molecular main compounds (Moreno et al. 2005). In order to follow-up our monitoring, new disk mapping observations took place in May 2006 using the IRAM-30m Telescope. Here we report the results of the recent measurements of CO, CS and HCN, and also the search for new species: H2CO, H2CS, CH3CN, CH3OH. Such trace compounds could have explained the mass losses observed in 2004, but no clear detections have been obtained after reasonable integration times. Estimates of the new CO, CS and HCN total masses and upper limits for the trace species searched for will be presented. The loss mechanisms will be discussed. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  1. Novel HCN2 Mutation Contributes to Febrile Seizures by Shifting the Channel's Kinetics in a Temperature-Dependent Manner

    PubMed Central

    Nakamura, Yuki; Shi, Xiuyu; Numata, Tomohiro; Mori, Yasuo; Inoue, Ryuji; Lossin, Christoph; Baram, Tallie Z.; Hirose, Shinichi

    2013-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel-mediated currents, known as Ih, are involved in the control of rhythmic activity in neuronal circuits and in determining neuronal properties including the resting membrane potential. Recent studies have shown that HCN channels play a role in seizure susceptibility and in absence and limbic epilepsy including temporal lobe epilepsy following long febrile seizures (FS). This study focused on the potential contributions of abnormalities in the HCN2 isoform and their role in FS. A novel heterozygous missense mutation in HCN2 exon 1 leading to p.S126L was identified in two unrelated patients with FS. The mutation was inherited from the mother who had suffered from FS in a pedigree. To determine the effect of this substitution we conducted whole-cell patch clamp electrophysiology. We found that mutant channels had elevated sensitivity to temperature. More specifically, they displayed faster kinetics at higher temperature. Kinetic shift by change of temperature sensitivity rather than the shift of voltage dependence led to increased availability of Ih in conditions promoting FS. Responses to cyclic AMP did not differ between wildtype and mutant channels. Thus, mutant HCN2 channels cause significant cAMP-independent enhanced availability of Ih during high temperatures, which may contribute to hyperthermia-induced neuronal hyperexcitability in some individuals with FS. PMID:24324597

  2. HCN and HNC in comets C/2000 WM1 (Linear) and C/2002 C1 (Ikeya-Zhang).

    PubMed

    Irvine, William M; Bergman, Per; Lowe, Thomas B; Matthews, Henry; McGonagle, Douglas; Nummelin, Albert; Owen, Toby

    2003-12-01

    Comets have been suggested as a possibly significant source of organic molecules to the early Earth. Hydrogen cyanide (HCN) is important in models of prebiotic chemistry, but may be difficult to form in the early terrestrial environment, while hydrogen isocyanide (HNC) is a 'classical' tracer of interstellar ion-molecule chemistry. We have observed both HCN and HNC in 2 recent comets, bringing the number of comets with published measurements of the HNC/HCN abundance ratio to 6. The HNC/HCN ratio in comet Ikeya-Zhang appears to increase with decreasing heliocentric distance, as was previously observed for comet Hale-Bopp, indicating that the HNC is produced at least in part by processes in the cometary coma (atmosphere) and is not simply a constituent of the nuclear ices. Both comets C/2000 WMI (Linear) and C/2002 C1 (Ikeya-Zhang) exhibit values of the HNC/HCN ratio that appear to be too large (approximately 0.09-0.19) to be matched by current models of coma chemistry. Cometary HNC may be a photodissociation product of organic grains or large organic polymers stored in the nucleus. We have also set a limit on the emission from the NO radical in comet WM1. PMID:14601930

  3. Multifrequency electron spin resonance detection of solid-state organic free radicals in HCN polymer and a Titan tholin.

    PubMed

    Budil, David E; Roebber, John L; Liebman, Shirley A; Matthews, Clifford N

    2003-01-01

    Macromolecules derived from hydrogen cyanide (HCN) may be major components of the dark matter observed in bodies in the outer Solar System, which include comets and asteroids. HCN oligomers and polymers are readily formed at room temperature and react with water to produce polypeptides and alpha-amino acids or undergo pyrolysis to produce nitrogen heterocycles. Electron spin resonance (ESR) spectroscopy shows that HCN polymer mixtures contain a significant amount of long-lived organic free radicals that are primarily carbon-based. For comparison, we have also examined samples of tholins produced from experimental analogs of Titan aerosols, which has been shown by trace organic analysis to consist partly of HCN polymer. The "Titan tholin" exhibits at least two ESR signals that can be assigned to nitrogen- and carbon-centered radicals, although heating the sample eliminates the nitrogen centers and increases the signal from the carbon centers. This result suggests that the nitrogen-centered radicals may be thermodynamically less stable, but are kinetically trapped during the spark-discharge reactions that produce tholins from mixtures of gases such as methane and nitrogen. The results strongly support previous proposals of free radical mechanisms for HCN polymerization. PMID:14577881

  4. CRYOCHEM modeling of Titan's liquid: the effects of hydrogen cyanide (HCN)

    NASA Astrophysics Data System (ADS)

    Tan, S. P.; Kargel, J. S.; Adidharma, H.; Marion, G. M.

    2015-12-01

    It is widely known that Titan is the only body in the Solar System, other than Earth, that has an abundant liquid phase on its surface. Its liquid composition has been derived from thermodynamic models that assume equilibrium between liquid and the atmosphere. Efforts to obtain composition data of Titan's lakes have been made, in particular using bathymetry and microwave absorption analysis of Cassini fly-by data, the initial semi-quantitative findings of which include the dominant fraction of methane in liquids of northern lakes (Mastrogiuseppe et al., GRL 2013, 41, 1432). These efforts can constrain the composition of each component in the liquids of both northern lakes and Ontario Lacus in the southern hemisphere.A molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, was shown to reproduce the vertical composition profile of Titan's atmospheric methane measured by the Huygens probe (Tan et al., Icarus 2013, 222, 53). It was also used to calculate the liquid composition in equilibrium with the atmosphere. The results revealed exotic behavior of liquid density with respect to changes of temperature and pressure (Tan et al., Icarus 2015, 250, 64). Within a temperature range of 3.7 K between equatorial and Polar regions, the liquid composition changes from ethane-rich in the equator to methane-rich at polar latitudes, thus consistent with the bathymetry and microwave absorption analysis. This consistency will have to be tested quantitatively when the analysis is completed and gives us tighter compositional constraints. CRYOCHEM is currently enhanced by including HCN, the only nitrile that has an amount comparable to the heavy hydrocarbons already accounted for in the model. The reason for initially omitting HCN was the inability of the old version of CRYOCHEM to deal with electrically polar molecules such as HCN, which has a strong dipole moment. Its present inclusion brings the model fluids closer to the actual condition on

  5. Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes—A model

    NASA Astrophysics Data System (ADS)

    Kanani, S.; Pumir, A.; Krinsky, V.

    2008-01-01

    One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler Reuter model, as well as with the elaborate dynamic Luo Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I channels is low enough. At too high an expression level of I channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I channels observed in ventricular myocytes, both in the Beeler Reuter and in the dynamic Luo Rudy models are too high to allow to observe oscillations. With expression levels below ˜1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

  6. Competition between abstraction and exchange channels in H + HCN reaction: Full-dimensional quantum dynamics

    SciTech Connect

    Jiang, Bin; Guo, Hua

    2013-12-14

    Dynamics of the title reaction is investigated on an ab initio based potential energy surface using a full-dimensional quantum wave packet method within the centrifugal sudden approximation. It is shown that the reaction between H and HCN leads to both the hydrogen exchange and hydrogen abstraction channels. The exchange channel has a lower threshold and larger cross section than the abstraction channel. It also has more oscillations due apparently to quantum resonances. Both channels are affected by long-lived resonances supported by potential wells. Comparison with experimental cross sections indicates underestimation of the abstraction barrier height.

  7. High resolution observations of HCN and HCO+J = 3-2 in the disk and outflow of Mrk 231. Detection of vibrationally excited HCN in the warped nucleus

    NASA Astrophysics Data System (ADS)

    Aalto, S.; Garcia-Burillo, S.; Muller, S.; Winters, J. M.; Gonzalez-Alfonso, E.; van der Werf, P.; Henkel, C.; Costagliola, F.; Neri, R.

    2015-02-01

    Aims: Our goal is to study molecular gas properties in nuclei and large scale outflows/winds from active galactic nuclei (AGNs) and starburst galaxies. Methods: We obtained high resolution (0.̋25 to 0.̋90) observations of HCN and HCO+J = 3 → 2 of the ultraluminous QSO galaxy Mrk 231 with the IRAM Plateau de Bure Interferometer (PdBI). Results: We find luminous HCN and HCO+J = 3 → 2 emission in the main disk and we detect compact (r ≲ 0''&dotbelow;1 (90 pc)) vibrationally excited HCN J = 3 → 2ν2 = 1f emission centred on the nucleus. The velocity field of the vibrationally excited HCN is strongly inclined (position angle PA = 155°) compared to the east-west rotation of the main disk. The nuclear (r ≲ 0.̋1) molecular mass is estimated to 8 × 108 M⊙ with an average N(H2) of 1.2 × 1024 cm-2. Prominent, spatially extended (≳350 pc) line wings are found for HCN J = 3 → 2 with velocities up to ± 750 km s-1. Line ratios indicate that the emission is emerging in dense gas n = 104-5 × 105 cm-3 of elevated HCN abundance X(HCN) = 10-8-10-6. The highest X(HCN) also allows for the emission to originate in gas of more moderate density. We tentatively detect nuclear emission from the reactive ion HOC+ with HCO+/HOC+ = 10-20. Conclusions: The HCN ν2 = 1f line emission is consistent with the notion of a hot, dusty, warped inner disk of Mrk 231 where the ν2 = 1f line is excited by bright mid-IR 14 μm continuum. We estimate the vibrational temperature Tvib to 200-400 K. Based on relative source sizes we propose that 50% of the main HCN emission may have its excitation affected by the radiation field through IR pumping of the vibrational ground state. The HCN emission in the line wings, however, is more extended and thus likely not strongly affected by IR pumping. Our results reveal that dense clouds survive (and/or are formed) in the AGN outflow on scales of at least several hundred pc before evaporating or collapsing. The elevated HCN abundance in the

  8. 13C Tracking after 13CO2 Supply Revealed Diurnal Patterns of Wood Formation in Aspen1

    PubMed Central

    Mahboubi, Amir; Linden, Pernilla; Moritz, Thomas

    2015-01-01

    Wood of trees is formed from carbon assimilated in the photosynthetic tissues. Determining the temporal dynamics of carbon assimilation, subsequent transport into developing wood, and incorporation to cell walls would further our understanding of wood formation in particular and tree growth in general. To investigate these questions, we designed a 13CO2 labeling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula × tremuloides). Tracking of 13C incorporation to wood over a time course using nuclear magnetic resonance spectroscopy revealed diurnal patterns in wood cell wall biosynthesis. The dark period had a differential effect on 13C incorporation to lignin and cell wall carbohydrates. No 13C was incorporated into aromatic amino acids of cell wall proteins in the dark, suggesting that cell wall protein biosynthesis ceased during the night. The results show previously unrecognized temporal patterns in wood cell wall biosynthesis, suggest diurnal cycle as a possible cue in the regulation of carbon incorporation to wood, and establish a unique 13C labeling method for the analysis of wood formation and secondary growth in trees. PMID:25931520

  9. Origin of monoterpene emissions from boreal tree species: Determination of de novo and pool emissions by 13CO2 labeling

    NASA Astrophysics Data System (ADS)

    Rinne, J.; Ghirardo, A.; Koch, K.; Taipale, R.; Zimmer, I.; Schnitzler, J.

    2009-12-01

    Boreal forests emit a large amount of monoterpenes into the atmosphere. Traditionally these emissions are assumed to originate as evaporation from large storage pools. Thus their diurnal cycle would depend mostly on temperature. However, there is indication that a significant part of the monoterpene emission would originate directly from de novo synthesis. By applying 13CO2 fumigation and analyzing the isotope fractions with proton transfer reaction mass spectrometry (PTR-MS) and classical GC-MS we studied the origin of monoterpene emissions from some major Eurasian boreal and alpine tree species. We determined the fractions originating from de novo biosynthesis and from large internal monoterpene storages for three coniferous tree species with specialized monoterpene storage structures and one dicotyledon species without such structures. The emission from dicotyledon species Betula pendula originated solely from the de novo synthesis. The origin of the emissions from coniferous species was mixed with varying fraction originating from de novo synthesis (Pinus sylvestris 58%, Picea abies 33.5%, Larix decidua 9.8%) and the rest from large internal monoterpene storage pools. Application of the observed fractions of emission originating from de novo synthesis and large storage pools in a hybrid emission algorithm resulted in a better description of ecosystem scale monoterpene emissions from a boreal Scots pine forest stand.

  10. Optimization of [11C]HCN production and no-carrier-added [1-11C]amino acid synthesis.

    PubMed

    Iwata, R; Ido, T; Takahashi, T; Nakanishi, H; Iida, S

    1987-01-01

    The optimal conditions for the catalytic production of [11C]HCN from [11C]CO2 were investigated. [11C]CO2 was reduced to [11C]CH4 with H2 on Ni and then converted to [11C]HCN by reaction with NH3 on Pt in a radiochemical yield of more than 95% under the optimized conditions of an NH3 concentration of 5 vol%, a Pt furnace temperature of 920 degrees C, and a reaction gas flow rate of over 200 mL/min. Absorbers were used to remove O2 and H2O from the reaction gas. The synthesis of no-carrier-added [1-11C]amino acids from [11C]HCN via [11C]aminonitriles was successfully carried out. This method is suitable for automation of [1-11C]amino acid production. PMID:3032866

  11. Seasonal and interannual variations in HCN amounts in the upper troposphere and lower stratosphere observed by MIPAS

    NASA Astrophysics Data System (ADS)

    Glatthor, N.; Höpfner, M.; Stiller, G. P.; von Clarmann, T.; Funke, B.; Lossow, S.; Eckert, E.; Grabowski, U.; Kellmann, S.; Linden, A.; Walker, K. A.; Wiegele, A.

    2015-01-01

    We present a HCN climatology of the years 2002-2012, derived from FTIR limb emission spectra measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the ENVISAT satellite, with the main focus on biomass burning signatures in the upper troposphere and lower stratosphere. HCN is an almost unambiguous tracer of biomass burning with a tropospheric lifetime of 5-6 months and a stratospheric lifetime of about 2 years. The MIPAS climatology is in good agreement with the HCN distribution obtained by the spaceborne ACE-FTS experiment and with airborne in situ measurements performed during the INTEX-B campaign. The HCN amounts observed by MIPAS in the southern tropical and subtropical upper troposphere have an annual cycle peaking in October-November, i.e. 1-2 months after the maximum of southern hemispheric fire emissions. The probable reason for the time shift is the delayed onset of deep convection towards austral summer. Because of overlap of varying biomass burning emissions from South America and southern Africa with sporadically strong contributions from Indonesia, the size and strength of the southern hemispheric plume have considerable interannual variations, with monthly mean maxima at, for example, 14 km between 400 and more than 700 pptv. Within 1-2 months after appearance of the plume, a considerable portion of the enhanced HCN is transported southward to as far as Antarctic latitudes. The fundamental period of HCN variability in the northern upper troposphere is also an annual cycle with varying amplitude, which in the tropics peaks in May after and during the biomass burning seasons in northern tropical Africa and southern Asia, and in the subtropics peaks in July due to trapping of pollutants in the Asian monsoon anticyclone (AMA). However, caused by extensive biomass burning in Indonesia and by northward transport of part of the southern hemispheric plume, northern HCN maxima also occur around October/November in several years

  12. A compact laser-based spectrometer for detection of C2H2 in exhaled breath and HCN in vitro

    NASA Astrophysics Data System (ADS)

    Marchenko, D.; Neerincx, A. H.; Mandon, J.; Zhang, J.; Boerkamp, M.; Mink, J.; Cristescu, S. M.; Hekkert, S. te Lintel; Harren, F. J. M.

    2015-02-01

    We report on the development of a compact prototype near-infrared DBR laser-based spectrometer employing off-axis integrated cavity output spectroscopy. The spectrometer is capable of simultaneous detection of acetylene (C2H2) and CO2 at 1,529.2 nm as well as hydrogen cyanide (HCN) at 1,533.5 nm. The detection limits of 8 ppbv for C2H2 and 80 ppbv for HCN are achieved for the acquisition time of 1 s. The setup has been tested for online measurements of C2H2 in exhaled breath of a smoking subject and HCN resulting from the metabolism of Pseudomonas aeruginosa bacteria in vitro. Further improvements of the performance of the spectrometer are discussed.

  13. Measurement of 13CO2 in expired air as an index of compliance to a high carbohydrate diet naturally enriched in 13C.

    PubMed

    Gay, L J; Schutz, Y; DiVetta, V; Schneiter, P; Tappy, L; Jéquier, E

    1994-09-01

    The aim of this study was to determine whether breath 13CO2 measurements could be used to assess the compliance to a diet containing carbohydrates naturally enriched in 13C. The study was divided into two periods: Period 1 (baseline of 4 days) with low 13C/12C ratio carbohydrates. Period 2 (5 days) isocaloric diet with a high 13C/12C ratio (corn, cane sugar, pineapple, millet) carbohydrates. Measurements were made of respiratory gas exchange by indirect calorimetry, urinary nitrogen excretion and breath 13CO2 every morning in post-absorptive conditions, both in resting state and during a 45-min low intensity exercise (walking on a treadmill). The subjects were 10 healthy lean women (BMI 20.4 +/- 1.7 kg/m2, % body fat 24.4 +/- 1.3%), the 13C enrichment of oxidized carbohydrate and breath 13CO2 were compared to the enrichment of exogenous dietary carbohydrates. At rest the enrichment of oxidized carbohydrate increased significantly after one day of 13C carbohydrate enriched diet and reached a steady value (103 +/- 16%) similar to the enrichment of exogenous carbohydrates. During exercise, the 13C enrichment of oxidized carbohydrate remained significantly lower (68 +/- 17%) than that of dietary carbohydrates. The compliance to a diet with a high content of carbohydrates naturally enriched in 13C may be assessed from the measurement of breath 13CO2 enrichment combined with respiratory gas exchange in resting, postabsorptive conditions. PMID:7812411

  14. Study of the surface modification of LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Hashem, A. M. A.; Abdel-Ghany, A. E.; Eid, A. E.; Trottier, J.; Zaghib, K.; Mauger, A.; Julien, C. M.

    2011-10-01

    The surface of LiNi1/3Co1/3Mn1/3O2 (LNMCO) particles has been studied for material synthesized at 900 °C by a two-step process from a mixture of LiOH·H2O and metal oxalate [(Ni1/3Co1/3Mn1/3)C2O4] obtained by co-precipitation. Samples have been characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), Raman scattering (RS) spectroscopy, and magnetic measurements. We have investigated the effect of the heat treatment of particles at 600 °C with organic substances such as sucrose and starch. HRTEM images and RS spectra indicate that the surface of particles has been modified. The annealing does not lead to any carbon coating but it leads to the crystallization of the thin disordered layer on the surface of LiNi1/3Co1/3Mn1/3O2. The beneficial effect has been tested on the electrochemical properties of the LiNi1/3Co1/3Mn1/3O2 cathode materials. The capacity at 10C-rate is enhanced by 20% for post-treated LNMCO particles at 600 °C for half-an-hour.

  15. VizieR Online Data Catalog: CO and HCN observations of circumstellar envelopes (Loup+ 1993)

    NASA Astrophysics Data System (ADS)

    Loup, C.; Forveille, T.; Omont, A.; Paul, J. F.

    1997-06-01

    We have searched the literature for all observations of the 12CO(1-0), 12CO(2-1), and HCN(1-0) lines in circumstellar envelopes of late type stars published between January 1985 and September 1992. We report data for 1361 observations (stellar velocity, expansion velocity, peak intensity, integrated area, noise level). This CO-HCN sample now contains 444 sources. 184 are identified as oxygen-rich, 205 as carbon-rich, and there are 9 S stars. About 85% of the sources are AGB stars. There are 32 planetary nebulae and about thirty post-AGB stars candidates. Besides results of millimeter observations, we also list identifications, coordinates, IRAS data, chemical and spectral types for every source. For AGB stars, we have estimated (or compiled) bolometric fluxes and distances for 349 sources, and mass loss rates deduced from CO results for 324 sources, taking into account the influence of the CO photodissociation radius. We also list mass loss rates derived from detailed models of CO emission which we could find in the literature. (7 data files).

  16. Exercise training reduces resting heart rate via downregulation of the funny channel HCN4.

    PubMed

    D'Souza, Alicia; Bucchi, Annalisa; Johnsen, Anne Berit; Logantha, Sunil Jit R J; Monfredi, Oliver; Yanni, Joseph; Prehar, Sukhpal; Hart, George; Cartwright, Elizabeth; Wisloff, Ulrik; Dobryznski, Halina; DiFrancesco, Dario; Morris, Gwilym M; Boyett, Mark R

    2014-01-01

    Endurance athletes exhibit sinus bradycardia, that is a slow resting heart rate, associated with a higher incidence of sinus node (pacemaker) disease and electronic pacemaker implantation. Here we show that training-induced bradycardia is not a consequence of changes in the activity of the autonomic nervous system but is caused by intrinsic electrophysiological changes in the sinus node. We demonstrate that training-induced bradycardia persists after blockade of the autonomous nervous system in vivo in mice and in vitro in the denervated sinus node. We also show that a widespread remodelling of pacemaker ion channels, notably a downregulation of HCN4 and the corresponding ionic current, If. Block of If abolishes the difference in heart rate between trained and sedentary animals in vivo and in vitro. We further observe training-induced downregulation of Tbx3 and upregulation of NRSF and miR-1 (transcriptional regulators) that explains the downregulation of HCN4. Our findings provide a molecular explanation for the potentially pathological heart rate adaptation to exercise training. PMID:24825544

  17. Millimeter-wave observations of Saturn, Uranus, and Neptune - CO and HCN on Neptune

    NASA Technical Reports Server (NTRS)

    Rosenqvist, Jan; Lellouch, Emmanuel; Romani, Paul N.; Paubert, Gabriel; Encrenaz, Therese

    1992-01-01

    Saturn, Uranus, and Neptune were observed at millimeter wavelengths with the IRAM 30 m telescope. The major result is the detection of CO and HCN in Neptune's stratosphere, with respective mixing ratios of (6.5 +/- 3.5) x 10 exp -7 and (3 +/- 1.5) x 10 exp -10. CO seems to be present in Neptune's troposphere as well and to slowly decrease with altitude (scale height about 200 km). HCN is probably formed from reactions between CH3 and N, which can be supplied in sufficient amounts by escape from Triton's atmosphere. The origin of CO, however, is more problematic, because: (1) thermochemical models fail to reproduce the observed abundance by a factor of about 1000; and (2) an external source would require a very large flux of oxygen. CO appears to be at least 15 times less abundant on Uranus than on Neptune. Finally, an upper limit of 10 exp -7 for CO in Saturn's stratosphere suggests an internal origin for Saturnian CO.

  18. VIBRATIONALLY EXCITED HCN AROUND AFGL 2591: A PROBE OF PROTOSTELLAR STRUCTURE

    SciTech Connect

    Veach, Todd J.; Groppi, Christopher E.; Hedden, Abigail

    2013-03-10

    Vibrationally excited molecules with submillimeter rotational transitions are potentially excellent probes of physical conditions near protostars. This study uses observations of the v = 1 and v = 2 ro-vibrational modes of HCN (4-3) to probe this environment. The presence or absence and relative strengths of these ro-vibrational lines probe the gas excitation mechanism and physical conditions in warm, dense material associated with protostellar disks. We present pilot observations from the Heinrich Hertz Submillimeter Telescope and follow-up observations from the Submillimeter Array. All vibrationally excited HCN (4-3) v = 0, v = 1, and v = 2 lines were observed. The existence of the three v = 2 lines at approximately equal intensity imply collisional excitation with a density of greater than (10{sup 10} cm{sup -3}) and a temperature of >1000 K for the emitting gas. This warm, high-density material should directly trace structures formed in the protostellar envelope and disk environment. Further, the line shapes of the v = 2 emission may suggest a Keplerian disk. This Letter demonstrates the utility of this technique which is of particular interest due to the recent inauguration of the Atacama Large Millimeter Array.

  19. ALMA Imaging of HCN, CS, and Dust in Arp 220 and NGC 6240

    NASA Astrophysics Data System (ADS)

    Scoville, Nick; Sheth, Kartik; Walter, Fabian; Manohar, Swarnima; Zschaechner, Laura; Yun, Min; Koda, Jin; Sanders, David; Murchikova, Lena; Thompson, Todd; Robertson, Brant; Genzel, Reinhard; Hernquist, Lars; Tacconi, Linda; Brown, Robert; Narayanan, Desika; Hayward, Christopher C.; Barnes, Joshua; Kartaltepe, Jeyhan; Davies, Richard; van der Werf, Paul; Fomalont, Edward

    2015-02-01

    We report ALMA Band 7 (350 GHz) imaging at 0.''4-0.''6 resolution and Band 9 (696 GHz) at ~0.''25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 109 M ⊙within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are nH_2 ˜ 10^5 cm-3 at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n H2 ~ 2 × 105 cm-3. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

  20. The 7-channel FIR HCN interferometer on J-TEXT tokamak

    NASA Astrophysics Data System (ADS)

    Chen, W.; Gao, L.; Chen, J.; Li, Q.; Wang, Z. J.; Zhuang, G.

    2012-01-01

    A seven-channel far-infrared hydrogen cyanide (HCN) laser interferometer has been established aiming to provide the line integrated plasma density for the J-TEXT experimental scenarios. A continuous wave glow discharge HCN laser designed with a cavity length 3.4 m is used as the laser source with a wavelength of 337 μm and an output power up to 100 mW. The system is configured as a Mach-Zehnder type interferometer. Phase modulation is achieved by a rotating grating, with a modulation frequency of 10 kHz which corresponds to the temporal resolution of 0.1 ms. The beat signal is detected by TGS detector. The phase shift induced by the plasma is derived by the comparator with a phase sensitivity of 0.06 fringe. The experimental results measured by the J-TEXT interferometer are presented in details. In addition, the inversed electron density profile done by a conventional approach is also given. The kinematic viscosity of dimethyl silicone and vibration control is key issues for the system performance. The laser power stability under different kinematic viscosity of silicone oil is presented. A visible improvement of measured result on vibration reduction is shown in the paper.

  1. 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

  2. Phospholipid transfer protein (PLTP) reduces phosphorylation of tau in human neuronal cells (HCN2)

    PubMed Central

    Dong, Weijiang; Albers, John J.; Vuletic, Simona

    2009-01-01

    Tau function is regulated by phosphorylation, and abnormal tau phosphorylation in neurons is one of the key processes associated with development of Alzheimer’s disease and other tauopathies. In this study we provide evidence that phospholipid transfer protein (PLTP), one of the main lipid transfer proteins in the brain, significantly reduces levels of phosphorylated tau, and increases levels of the inactive form of glycogen synthase kinase-3β (GSK3β) in HCN2 cells. Furthermore, inhibition of the phosphatidylinositol-3 kinase (PI3K) reversed the PLTP-induced increase in levels of GSK3β phosphorylated at serine 9 (pGSK3βSer9) and partially reversed the PLTP-induced reduction in tau phosphorylation. We provide evidence that the PLTP-induced changes are not due to activation of Disabled-1 (Dab1), since PLTP reduced levels of total and phosphorylated Dab1 in HCN2 cells. We have also shown that inhibition of tyrosine kinase activity of insulin receptor (IR) and/or insulin-like growth factor 1 (IGF1) receptor (IGFR) reverses PLTP-induced increase in levels of phosphorylated Akt (pAktThr308 and pAktSer473), suggesting that PLTP-mediated activation of the PI3K/Akt pathway is dependent on IR/IGFR receptor tyrosine kinase activity. Our study suggests that PLTP may be an important modulator of signal transduction pathways in human neurons. PMID:19472218

  3. Hydrogen-bonded glycine-HCN complexes in gas phase: structure, energetics, electric properties and cooperativity

    NASA Astrophysics Data System (ADS)

    Machado da Silva, Arnaldo; Chakrabarty, Sumana; Chaudhuri, Puspitapallab

    2015-03-01

    Twelve hydrogen-bonded complexes of glycine and hydrogen cyanide have been studied using high-level quantum-chemical calculations in gas phase. In particular, six 1:1 glycine-HCN dimers and six 1:2 glycine-HCN trimers have been considered. Besides the characteristics of the hydrogen bonds and their effect on molecular structure and energetics, several molecular electric properties have been calculated utilising two different models: MP2/6-31++G(d,p) and DFT-B3LYP/6-31++G(d,p). Although the structural parameters calculated by the two models are similar, equilibrium electronic energies of the clusters show model dependence. The lowest energy dimer is same in both the models which is ca. 3.0 kcal/mol more stable than the highest energy dimer. However, the lowest energy trimer is different in two methods. The energetic difference of stability between the highest and lowest trimer is 4.2 kcal/mol (4.4 kcal/mol) at an MP2 (B3LYP) level of calculation. The bond angles of glycine, in particular, are quite sensitive to the hydrogen-bond formation. Four out of six trimers are found to be strongly cooperative in both the models. Significant changes of dipole moments and polarisabilities of isolated glycine and hydrogen cyanide are observed due to the formation of hydrogen bonding. The Rayleigh scattering intensities of all clusters are much larger than those of their constituent monomers.

  4. HCO{sup +} AND HCN J = 3-2 ABSORPTION TOWARD THE CENTER OF CENTAURUS A

    SciTech Connect

    Muller, Sebastien; Dinh-V-Trung

    2009-05-01

    We have investigated the presence of dense gas toward the radio source Cen A by looking at the absorption of the HCO{sup +} and HCN (3-2) lines in front of the bright continuum source with the Submillimeter Array. We detect narrow HCO{sup +} (3-2) absorption, and tentatively HCN (3-2), close to the systemic velocity. For both molecules, the J = 3 - 2 absorption is much weaker than for the J = 1 - 0 line. From simple excitation analysis, we conclude that the gas density is of the order of a few 10{sup 4} cm{sup -3} for a column density N(HCO{sup +})/{delta}V of 3 x 10{sup 12} cm{sup -2} km{sup -1} s and a kinetic temperature of 10 K. In particular, we find no evidence for molecular gas density higher than a few 10{sup 4} cm{sup -3} on the line of sight to the continuum source. We discuss the implications of our finding on the nature of the molecular gas responsible for the absorption toward Cen A.

  5. Absolute cross sections for dissociative electron attachment to HCN and DCN

    SciTech Connect

    May, O.; Kubala, D.; Allan, M.

    2010-07-15

    Absolute partial cross sections for the formation of CN{sup -} in dissociative electron attachment to HCN and DCN have been measured using a time-of-flight ion spectrometer combined with a trochoidal electron monochromator to be 940pm{sup 2} for CN{sup -}/HCN and 340pm{sup 2} for CN{sup -}/DCN at peaks of the bands due to the {sup 2{Pi}}-shape resonance. The dissociative electron attachment bands were then recorded under higher resolution, 60 meV, with a trochoidal monochromator plus quadrupole mass filter combination and found to have a nearly vertical onset at the threshold energy and to peak at 1.85 eV. Broad structure was observed on the bands, assigned to formation of vibrationally excited CN{sup -}, from which the branching ratios could be determined to be 1,0.49, and 0.22 for the formation of CN{sup -} in the v=0,1, and 2 states, respectively. The results are compared to the recent multidimensional ab initio calculations of Chourou and Orel [Phys. Rev. A 80, 032709 (2009)].

  6. THE HCN-WATER RATIO IN THE PLANET FORMATION REGION OF DISKS

    SciTech Connect

    Najita, Joan R.; Salyk, Colette; Carr, John S.; Pontoppidan, Klaus M.; Van Dishoeck, Ewine F.; Blake, Geoffrey A.

    2013-04-01

    We find a trend between the mid-infrared HCN/H{sub 2}O flux ratio and submillimeter disk mass among T Tauri stars in Taurus. While it may seem puzzling that the molecular emission properties of the inner disk (HCN/H{sub 2}O ratio and disk mass is of interest as trends like this among T Tauri disk properties are relatively rare.

  7. Structure and properties of the radiation-induced intermediates produced from HCN in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Kameneva, Svetlana V.; Tyurin, Daniil A.; Feldman, Vladimir I.

    2016-07-01

    In this work we report the results of systematic studies on the radiation-induced transformations in HCN/Ng systems (Ng=Ne, Ar, Kr or Xe) at 7 K using a combination of FTIR and EPR spectroscopy. It was shown that HCN underwent efficient decomposition producing H atoms, CN radicals and HNC isomer. The thermally induced reactions of H atoms in different matrices result in the formation of two isomeric radicals, H2CN and trans-HCNH, the former being predominated. The temperature dependent dynamics of CN and H2CN radicals in a krypton matrix was observed by EPR spectroscopy in solid krypton. The vibrational frequencies, IR intensities and magnetic resonance parameters of H2CN and trans-HCNH radicals calculated at the CCSD(T) level are in reasonable agreement with the experimental results. It was found that HCNH radical could be effectively bleached with visible light. The comparison of experimental and computational data made it possible to assign a new vibrational band at 918 cm-1 in an Ar matrix (and the corresponding bands in Kr and Xe) to trans-HCNH radical. In addition, HKrCN was found in the case of krypton, whereas HXeCN and HXeNC were produced in solid xenon. The reaction mechanisms and contribution of different channels are discussed.

  8. Global bending quantum number and the absence of monodromy in the HCN{r_reversible}CNH molecule

    SciTech Connect

    Efstathiou, K.; Sadovskii, D.A.; Joyeux, M.

    2004-03-01

    We introduce and analyze a model system based on a deformation of a spherical pendulum that can be used to reproduce large amplitude bending vibrations of flexible triatomic molecules with two stable linear equilibria. On the basis of our model and the recent vibrational potential [ J. Chem. Phys. 115, 3706 (2001) ], we analyze the HCN/CNH isomerizing molecule. We find that HCN/CNH has no monodromy and introduce the second global bending quantum number for this system at all energies where the potential is expected to work. We also show that LiNC/LiCN is a qualitatively different system with monodromy.

  9. Ligand addition versus substitution in the slow reaction of 13CO with Mn(CO)-4 in a flowing afterglow apparatus

    NASA Astrophysics Data System (ADS)

    McDonald, Richard N.; Schmidt, Myron A.

    1992-09-01

    The gas-phase reactions of Mn(CO)-4 with CO and 13CO are reported. Only addition was observed with CO producing Mn(CO)-5 (kapp = (2.5±0.2) × 10-12 cm3 molecule-1 s-1). Both addition (kadd = (3.2 ±0.4) × 10-12 cm3 molecule-1 s-1) and substitution (ksub = (1.2 ± 0.4) × 10-12 cm3 molecule-1 s-1) product-forming channels were observed in the reaction with 13CO. The average branching fractions for addition and thermoneutral substitution are 0.74 and 0.26 respectively. These branching fractions and the 70% collisional quenching efficiency of the excited addition intermediates [Mn(13CO)(CO)-4]* with the helium buffer gas are essentially the same values as those previously obtained for the quenching/decomposition of [Fe(13CO)(CO)[radical sign]-3]*. The ground electronic state of Mn(CO)-4 is believed to be the triplet because the negative ion is isoelectronic with Fe(CO)4, a known ground state triplet complex. Thus, the slow rate of the Mn(CO)-4/CO reaction (reaction EFFICIENCY = 0.0036) is considered to be the result of the spin-forbidden curve crossing of the triplet Mn(CO)-4 + CO inlet surface to the attractive singlet Mn(CO)-4 + CO --> singlet Mn(CO)-5 product surface. Comparisons with the results from the fast spin-allowed addition/substitution reactions of Fe(CO)[radical sign]-3 with 13CO are given.

  10. Precise measurements of the total concentration of atmospheric CO2 and 13CO2/12CO2 isotopic ratio using a lead-salt laser diode spectrometer.

    PubMed

    Croizé, Laurence; Mondelain, Didier; Camy-Peyret, Claude; Delmotte, Marc; Schmidt, Martina

    2008-04-01

    We have developed a tunable diode laser spectrometer, called SIMCO (spectrometer for isotopic measurements of CO(2)), for determining the concentrations of (12)CO(2) and (13)CO(2) in atmospheric air, from which the total concentration of CO(2) and the isotopic composition (expressed in delta units) delta(13)CO(2) are calculated. The two concentrations are measured using a pair of lines around 2290.1 cm(-1), by fitting a line profile model, taking into account the confinement narrowing effect to achieve a better accuracy. Using the Allan variance, we have demonstrated (for an integration time of 25 s) a precision of 0.1 ppmv for the total CO(2) concentration and of 0.3[per thousand] for delta(13)CO(2). The performances on atmospheric air have been tested during a 3 days campaign by comparing the SIMCO instrument with a gas chromatograph (GC) for the measurement of the total CO(2) concentration and with an isotopic ratio mass spectrometer (MS) for the isotopic composition. The CO(2) concentration measurements of SIMCO are in very good agreement with the GC data with a mean difference of Delta(CO(2))=0.16+/-1.20 ppmv for a comparison period of 45 h and the linearity of the concentration between the two instruments is also very good (slope of correlation: 0.9996+/-0.0003) over the range between 380 and 415 ppmv. For delta(13)CO(2), the comparison with the MS data shows a larger mean difference of Delta(delta(13)CO(2))=(-1.9+/-1.2)[per thousand], which could be partly related to small residual fluctuations of the overall SIMCO instrument response. PMID:18447517

  11. Infrared Spectroscopic Study of the Adsorption of HCN by gamma-Al2O3: Competition with Triethylenediamine for Adsorption Sites

    SciTech Connect

    Kim, S.; Sorescu, D.C.; Yates, J.T., Jr.

    2007-04-12

    The adsorption and vibrational properties of chemisorbed HCN on Lewis acid sites, Lewis base sites, and Brønsted Al-OH acid sites on a partially hydroxylated [gamma]-Al2O3 surface have been obtained by a combination of FTIR and density functional theory studies. The vibrational modes from the molecular and dissociative adsorption of HCN were assigned by using deuterium and 13C-labeled D13CN molecules at 170 K. In addition, [eta]2(C, N)-HCN bonding is also found from the [nu](CdN) vibrational spectra. Good correlation of the calculated vibrational frequencies for the adsorbed species with experimental data is found. The effect of triethylenediamine (TEDA) (also called 1, 4-diazabicyclo [2.2.2]octane, DABCO) on the adsorption of hydrogen cyanide (HCN) on the high area [gamma]-Al2O3 surface has been investigated using transmission FTIR spectroscopy. During HCN adsorption on TEDA-functionalized surfaces, there is no spectral change or emerging feature in either the TEDA or HCN spectral regions, indicating that no direct interaction occurs between these two molecules. Instead, we found that TEDA competes with HCN for the active sites on [gamma]-Al2O3. The observed [nu](C [identical with] N) mode on a TEDA-precovered surface is due to the HCN adsorption on Lewis base sites (Al-O-Al) which are less affected by TEDA preadsorption.

  12. Evaluating the Community Land Model in a pine stand with shading manipulations and 13CO2 labeling

    NASA Astrophysics Data System (ADS)

    Mao, J.; Ricciuto, D. M.; Thornton, P. E.; Warren, J. M.; King, A. W.; Shi, X.; Iversen, C. M.; Norby, R. J.

    2016-02-01

    Carbon allocation and flow through ecosystems regulates land surface-atmosphere CO2 exchange and thus is a key, albeit uncertain, component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked carbon allocation through a young Pinus taeda stand following pulse labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that were used to evaluate terrestrial biosphere model simulations of rapid shifts in carbon allocation and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbon and water dynamics in relation to manipulative shading treatments and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. When calibrated with pretreatment observations, CLM4 was capable of closely simulating stand-level biomass, transpiration, leaf-level photosynthesis, and pre-labeling 13C values. Over the 3-week treatment period, CLM4 generally reproduced the impacts of shading on soil moisture changes, relative change in stem carbon, and soil CO2 efflux rate. Transpiration under moderate shading was also simulated well by the model, but even with optimization we were not able to simulate the high levels of transpiration observed in the heavy shading treatment, suggesting that the Ball-Berry conductance model is inadequate for these conditions. The calibrated version of CLM4 gave reasonable estimates of label concentration in phloem and in soil surface CO2 after 3 weeks of shade treatment, but it lacks the mechanisms needed to track the labeling pulse through plant tissues on shorter timescales. We developed a conceptual model for photosynthate transport based on the experimental observations, and we discussed conditions under which the hypothesized mechanisms could have an important influence on model behavior in larger-scale applications

  13. Multiscale observations of CO2, 13CO2, and pollutants at Four Corners for emission verification and attribution

    PubMed Central

    Lindenmaier, Rodica; Dubey, Manvendra K.; Henderson, Bradley G.; Butterfield, Zachary T.; Herman, Jay R.; Rahn, Thom; Lee, Sang-Hyun

    2014-01-01

    There is a pressing need to verify air pollutant and greenhouse gas emissions from anthropogenic fossil energy sources to enforce current and future regulations. We demonstrate the feasibility of using simultaneous remote sensing observations of column abundances of CO2, CO, and NO2 to inform and verify emission inventories. We report, to our knowledge, the first ever simultaneous column enhancements in CO2 (3–10 ppm) and NO2 (1–3 Dobson Units), and evidence of δ13CO2 depletion in an urban region with two large coal-fired power plants with distinct scrubbing technologies that have resulted in ∆NOx/∆CO2 emission ratios that differ by a factor of two. Ground-based total atmospheric column trace gas abundances change synchronously and correlate well with simultaneous in situ point measurements during plume interceptions. Emission ratios of ∆NOx/∆CO2 and ∆SO2/∆CO2 derived from in situ atmospheric observations agree with those reported by in-stack monitors. Forward simulations using in-stack emissions agree with remote column CO2 and NO2 plume observations after fine scale adjustments. Both observed and simulated column ∆NO2/∆CO2 ratios indicate that a large fraction (70–75%) of the region is polluted. We demonstrate that the column emission ratios of ∆NO2/∆CO2 can resolve changes from day-to-day variation in sources with distinct emission factors (clean and dirty power plants, urban, and fires). We apportion these sources by using NO2, SO2, and CO as signatures. Our high-frequency remote sensing observations of CO2 and coemitted pollutants offer promise for the verification of power plant emission factors and abatement technologies from ground and space. PMID:24843169

  14. VOLTAGE-DEPENDENT OPENING OF HCN CHANNELS: FACILITATION OR INHIBITION BY THE PHYTOESTROGEN, GENISTEIN, IS DETERMINED BY THE ACTIVATION STATUS OF THE CYCLIC NUCLEOTIDE GATING RING

    PubMed Central

    Rozario, Anjali. O.; Turbendian, Harma K.; Fogle, Keri J.; Olivier, Nelson B.; Tibbs, Gareth R.

    2009-01-01

    Investigation of the mechanistic bases and physiological importance of cAMP regulation of HCN channels has exploited an arginine to glutamate mutation in the nucleotide-binding fold, an approach critically dependent on the mutation selectively lowering the channel’s nucleotide affinity. In apparent conflict with this, in intact Xenopus oocytes, HCN and HCN-RE channels exhibit qualitatively and quantitatively distinct responses to the tyrosine kinase inhibitor, genistein – the estrogenic isoflavonoid strongly depolarizes the activation midpoint of HCN1-R538E, but not HCN1 channels (+9.8 mV ± 0.9 versus +2.2 mV ± 0.6) and hyperpolarizes gating of HCN2 (−4.8 mV ± 1.0) but depolarizes gating of HCN2-R591E (+13.2 mV ± 2.1). However, excised patch recording, X-ray crystallography and modeling reveal this is not due to either a fundamental effect of the mutation on channel gating per se or of genistein acting as a mutation-sensitive partial agonist at the cAMP site. Rather, we find that genistein equivalently moves both HCN and HCN-RE channels closer to the open state (rendering the channels inherently easier to open but at a cost of decreasing the coupling energy of cAMP) and that the anomaly reflects a balance of these energetic effects with the isoform specific inhibition of activation by the nucleotide gating ring and relief of this by endogenous cAMP. These findings have specific implications with regard to findings based on HCN-RE channels and kinase antagonists and general implications with respect to interpretation of drug effects in mutant channel backgrounds. PMID:19524546

  15. hERG Potassium Channel Blockade by the HCN Channel Inhibitor Bradycardic Agent Ivabradine

    PubMed Central

    Melgari, Dario; Brack, Kieran E.; Zhang, Chuan; Zhang, Yihong; El Harchi, Aziza; Mitcheson, John S.; Dempsey, Christopher E.; Ng, G. André; Hancox, Jules C.

    2015-01-01

    Background Ivabradine is a specific bradycardic agent used in coronary artery disease and heart failure, lowering heart rate through inhibition of sinoatrial nodal HCN‐channels. This study investigated the propensity of ivabradine to interact with KCNH2‐encoded human Ether‐à‐go‐go–Related Gene (hERG) potassium channels, which strongly influence ventricular repolarization and susceptibility to torsades de pointes arrhythmia. Methods and Results Patch clamp recordings of hERG current (IhERG) were made from hERG expressing cells at 37°C. IhERG was inhibited with an IC50 of 2.07 μmol/L for the hERG 1a isoform and 3.31 μmol/L for coexpressed hERG 1a/1b. The voltage and time‐dependent characteristics of IhERG block were consistent with preferential gated‐state‐dependent channel block. Inhibition was partially attenuated by the N588K inactivation‐mutant and the S624A pore‐helix mutant and was strongly reduced by the Y652A and F656A S6 helix mutants. In docking simulations to a MthK‐based homology model of hERG, the 2 aromatic rings of the drug could form multiple π‐π interactions with the aromatic side chains of both Y652 and F656. In monophasic action potential (MAP) recordings from guinea‐pig Langendorff‐perfused hearts, ivabradine delayed ventricular repolarization and produced a steepening of the MAPD90 restitution curve. Conclusions Ivabradine prolongs ventricular repolarization and alters electrical restitution properties at concentrations relevant to the upper therapeutic range. In absolute terms ivabradine does not discriminate between hERG and HCN channels: it inhibits IhERG with similar potency to that reported for native If and HCN channels, with S6 binding determinants resembling those observed for HCN4. These findings may have important implications both clinically and for future bradycardic drug design. PMID:25911606

  16. High-Resolution 4.7 Micron Keck/NIRSPEC Spectra of Protostars. II. Detection of the 13CO Isotope in Icy Grain Mantles

    NASA Astrophysics Data System (ADS)

    Boogert, A. C. A.; Blake, G. A.; Tielens, A. G. G. M.

    2002-09-01

    The high-resolution (R=25,000) infrared M-band spectrum of the massive protostar NGC 7538 IRS 9 shows a narrow absorption feature at 4.779 μm (2092.3 cm-1) that we attribute to the vibrational stretching mode of the 13CO isotope in pure CO icy grain mantles. This is the first detection of 13CO in icy grain mantles in the interstellar medium. The 13CO band is a factor of 2.3 narrower than the apolar component of the 12CO band. With this in mind, we discuss the mechanisms that broaden solid-state absorption bands. It is shown that ellipsoidally shaped pure CO grains fit the bands of both isotopes at the same time. Slightly worse but still reasonable fits are also obtained by CO embedded in N2-rich ices and thermally processed O2-rich ices. In addition, we report new insights into the nature and evolution of interstellar CO ices by comparing the very high resolution multicomponent solid 12CO spectrum of NGC 7538 IRS 9 with that of the previously studied low-mass source L1489 IRS. The narrow absorption of apolar CO ices is present in both spectra but much stronger in NGC 7538 IRS 9. It is superposed on a smooth broad absorption feature well fitted by a combination of CO2 and H2O-rich laboratory CO ices. The abundances of the latter two ices, scaled to the total H2O ice column, are the same in both sources. We thus suggest that thermal processing manifests itself as evaporation of apolar ices only and not the formation of CO2 or polar ices. Finally, the decomposition of the 12CO band is used to derive the 12CO/13CO abundance ratio in apolar ices. A ratio of 12CO/13CO=71+/-15 (3 σ) is deduced, in good agreement with gas-phase CO studies (~77) and the solid 12CO2/13CO2 ratio of 80+/-11 found in the same line of sight. The implications for the chemical path along which CO2 is formed are discussed. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the

  17. HCN SPECTROSCOPY OF COMET 73P/SCHWASSMANN-WACHMANN 3. A STUDY OF GAS EVOLUTION AND ITS LINK TO CN

    SciTech Connect

    Paganini, L.; Hartogh, P.; Villanueva, G. L.; Lara, L. M.; Lin, Z. Y.; Kueppers, M.; Faure, A.

    2010-06-01

    In 2006 May, comet 73P/Schwassmann-Wachmann 3 experienced large outburst activity allowing us to study the gas production rate of fresh material released from the nucleus. We observed the comet in a coordinated campaign using millimeter and optical facilities at heliocentric distances between 0.966 and 1.033 AU. During this time, we had the opportunity to follow the post-outburst evolution of fragment B, which evidenced larger production rates in comparison to fragment C, the latter showing a rather stable gas production rate (Q {sub HCN} {approx}2 x 10{sup 25} molecules s{sup -1}). In addition to the investigation of the gas evolution, we studied the possible role of HCN and dust as progenitors for the CN radical. From our joint observations on May 12, we observed a high correlation of CN with HCN and low correlation with the continuum emission (grains). Herewith, our study supports the view of HCN as a major source of CN, although the presence of other sources for cyanide cannot be fully ruled out.

  18. Cocaine sensitization increases Ih current channel subunit 2 (HCN2) protein expression in structures of the Mesocorticolimbic System

    PubMed Central

    Santos-Vera, Bermary; Vázquez-Torres, Rafael; García Marrero, Hermes G.; Ramos Acevedo, Juan M.; Arencibia-Albite, Francisco; Vélez-Hernández, María E.; Miranda, Jorge D.; Jiménez-Rivera, Carlos A.

    2013-01-01

    Alteration of the biological activity among neuronal components of the Mesocorticolimbic (MCL) system has been implicated in the pathophysiology of drug abuse. Changes in the electrophysiological properties of neurons involved in the reward circuit seem to be of utmost importance in addiction. The Hyperpolarization-Activated Cyclic-Nucleotide Current, Ih, is a prominent mixed cation current present in neurons. The biophysical properties of the Ih and its potential modulatory role in cell excitability depend on the expression profile of the Hyperpolarization-activated cyclic nucleotide gated channel (HCN) subunits. We investigated whether cocaine-induced behavioral sensitization, an animal model of drug addiction, elicits region-specific changes in the expression of the HCN2 channel’s subunit in the MCL system. Tissue samples from the ventral tegmental area, prefrontal cortex, nucleus accumbens and hippocampus were analyzed using Western Blot. Our findings demonstrate that cocaine treatment induced a significant increase in the expression profile of the HCN2 subunit in both, its glycosylated and non-glycosylated protein isoforms, in all areas tested. The increase in the glycosylated isoform was only observed in the ventral tegmental area. Together, these data suggest that the observed changes in MCL excitability during cocaine addiction might be associated to alterations in the subunit composition of their HCN channels. PMID:23203153

  19. A search for SiO, OH, CO and HCN radio emission from silicate-carbon stars

    NASA Technical Reports Server (NTRS)

    Little-Marenin, I. R.; Sahai, R.; Wannier, P. G.; Benson, P. J.; Gaylard, M.; Omont, A.

    1994-01-01

    We report upper limits for radio emission of SiO at 86 and 43 GHz, of OH at 1612 and 1665/1667 MHz, of CO at 115 GHz and HCN at 88.6 GHz in the silicate-carbon stars. These upper limits of SiO imply that oxygen-rich material has not been detected within 2R(sub star) of a central star even though the detected emission from silicate dust grains, H2O and OH maser establishes the presence of oxygen-rich material from about tens to thousands of AU of a central star. The upper limit of the SiO abundance is consistent with that found in oxygen-rich envelopes. Upper limits of the mass loss rate (based on the CO data) are estimated to be between 10(exp -6) to 10(exp -7) solar mass/yr assuming a distance of 1.5 kpc for these stars. The absence of HCN microwave emission implies that no carbon-rich material can be detected at large distances (thousands of AU) from a central star. The lack of detections of SiO, CO, and HCN emission is most likely due to the large distances of these stars. A number of C stars were detected in CO and HCN, but only the M supergiant VX Sgr was detected in CO.

  20. Hidden Molecules in Planetary Nebulae: New Detections of HCN and HCO+ from a Multi-object Survey

    NASA Astrophysics Data System (ADS)

    Schmidt, D. R.; Ziurys, L. M.

    2016-02-01

    Searches for HCN and HCO+ have been conducted toward 17 planetary nebulae (PNs) in the age range 800 to 13,000 years using the facilities of the Arizona Radio Observatory (ARO). For both molecules, observations of the J=1\\to 0 transition near 88-89 GHz were carried out with the ARO 12 m, including measurements with the new ALMA prototype antenna, while the J=3\\to 2 lines near 265-267 GHz were sought with the ARO Sub-Millimeter Telescope (SMT). HCN and HCO+ were newly detected in 13 of the 17 target sources in at least one transition. Nine PNs were common to both molecules: Hb5, K3-17, K3-58, M1-7, M4-14, M3-28, M3-55, NGC 2440, and K4-47, while HCO+ was also identified in K3-83 and M2-9, and HCN in K3-45 and NGC 6772. From radiative transfer modeling, column densities for HCN and HCO+ in these sources were determined to be {N}{tot}({HCN}) ˜ 0.2-27 × 1013 cm-2 and {N}{tot}({{HCO}}+) ˜ 0.3-8.7 × 1013 cm-2. Gas densities, assumed to be in clumped regions, were established to be n(H2) ˜ 0.1-5.2 × 106 cm-3. Fractional abundances, relative to H2, for both molecules were found to be f(HCN) ˜ 0.1-9.1 × 10-7 and f(HCO+) ˜ 0.04-7.4 × 10-7. The abundances of both species were found to remain relatively constant with nebular age over a 10,000 year time span, in contrast to predictions of chemical models. The HCN/HCO+ ratio varied from 17 to <0.2, and roughly correlates with the C/O ratio. Polyatomic molecules appear to be common constituents of PNs.

  1. HCNMBC - A pulse sequence for H-(C)-N Multiple Bond Correlations at natural isotopic abundance

    NASA Astrophysics Data System (ADS)

    Cheatham, Steve; Gierth, Peter; Bermel, Wolfgang; Kupče, Ēriks

    2014-10-01

    We propose a pulse sequence, HCNMBC for multiple-bond H-(C)-N correlation experiments via one-bond 1J(C,H) and one- or multiple bond nJ(N,C) coupling constants (typically n = 1-3) at the natural isotopic abundance. A new adiabatic refocussing sequence is introduced to provide accurate and robust refocussing of both chemical shift and J-evolution over wide ranges of C-13 and N-15 frequencies. It is demonstrated that the proposed pulse sequence provides high quality spectra even for sub-milligram samples. We show that when a 1.7 mm cryoprobe is available as little as 10 μg of glycine in D2O is sufficient to obtain the HCNMBC spectrum in ca. 12 h. The preliminary results indicate that the pulse sequence has a great potential in the structure determination of nitrogen heterocycles especially in cases where synthesis produces regioisomers.

  2. Laser-driven isomerization of HCN → HNC: the importance of rotational excitation.

    PubMed

    Sun, Zhaopeng; Zheng, Yujun

    2015-03-26

    We report a time-dependent quantum wave packet theory, which is employed to interpret the isomerization dynamics of HCN molecules induced by an intense picosecond infrared laser field. Considering the molecular rotational degrees of the freedom, the wave functions are expanded in terms of molecular rotational bases. Our full-dimensional quantum model includes the full Coriolis coupling in the molecular kinetic energy Hamiltonian and dipole approximation in interaction terms. The numerical results show that the field-induced molecule rotational excitation plays an important role in the isomerization dynamical process. Some phenomena appear such as two-step two-photon absorption and highly oscillatory structure in rotational state distributions. The centrifugal sudden (CS) approximation calculation is also carried out and compared in this work; it is shown that the Coriolis couplings may lead to a significant decrease in the isomerization rate but highly enhanced molecular rotational excitation. PMID:25746130

  3. Fragmentation of HCN in optically selected mass spectrometry: Nonthermal ion cooling in helium nanodroplets

    SciTech Connect

    Lewis, William K.; Bemish, Raymond J.; Miller, Roger E.

    2005-10-08

    A technique that combines infrared laser spectroscopy and helium nanodroplet mass spectrometry, which we refer to as optically selected mass spectrometry, is used to study the efficiency of ion cooling in helium. Electron-impact ionization is used to form He{sup +} ions within the droplets, which go on to transfer their charge to the HCN dopant molecules. Depending upon the droplet size, the newly formed ion either fragments or is cooled by the helium before fragmentation can occur. Comparisons with gas-phase fragmentation data suggest that the cooling provided by the helium is highly nonthermal. An 'explosive' model is proposed for the cooling process, given that the initially hot ion is embedded in such a cold solvent.

  4. Low Temperature Measurements of HCN Broadened by N2 in the 14-micron Spectral Region

    SciTech Connect

    Smith, M.A.H.; Rinsland, Curtis P.; Blake, Thomas A.; Sams, Robert L.; Benner, D. C.; Devi, V. M.

    2008-04-01

    N2-broadening and N2-pressure-induced shift coefficients; and the temperature dependence exponent of the N2-broadening and the temperature dependent coefficients of N2-pressure-induced shifts have been measured for transitions in the v2 band of HCN from analysis of high-resolution absorption spectra recorded with two different Fourier transform spectrometers. A total of 34 laboratory spectra recorded at 0.002-0.005 cm-1 resolution and at temperatures ranging from 211 to 300 K were used in the determination of various spectral line parameters. A multispectrum nonlinear least squares curve fitting technique employing a modified Voigt line profile including speed dependence was used in the P- and R-branch measurements. In analyzing the Q branch transitions, the off-diagonal relaxation matrix element coefficients were included in analysis to fit the data. Present results are compared to previous measurements reported in the literature.

  5. The fast and slow ups and downs of HCN channel regulation

    PubMed Central

    Lewis, Alan S.; Estep, Chad M.; Chetkovich, Dane M.

    2015-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels (h channels) form the molecular basis for the hyperpolarization-activated current, Ih and modulation of h channels contributes to changes in cellular properties critical for normal functions in the mammalian brain and heart. Numerous mechanisms underlie h channel modulation during both physiological and pathological conditions, leading to distinct changes in gating, kinetics, surface expression, channel conductance or subunit composition of h channels. Here we provide a focused review examining contemporary mechanisms of h channel regulation, with an emphasis on recent findings regarding interacting proteins such as TRIP8b. This review is intended to serve as a comprehensive resource for physiologists to provide potential molecular mechanisms underlying functionally important changes in Ih in different biological models, as well as for molecular biologists to delineate the predicted h channel changes associated with complex regulatory mechanisms in both normal function and in disease states. PMID:20305382

  6. Electron-impact excitation of the low-lying electronic states of HCN

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Tanaka, H.; Srivastava, S. K.; Wicke, B. G.

    1977-01-01

    The first study of the low-energy electron-impact excitation of low-lying electronic transitions in the HCN molecule is reported. Measurements were made at incident electron energies of 11.6 and 21.6 eV in the energy-loss range of 3-10 eV, and at scattering angles of 20-130 deg. Inelastic scattering spectra were placed on the absolute cross-section scale by determining first the ratio of inelastic-to-elastic scattering cross sections, and then separately measuring the absolute elastic scattering cross section. Several new electronic transitions are observed which are intrinsically overlapped in the molecule itself. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-sections measurements, high-energy electron scattering spectra, optical absorption spectra, and ab initio molecular orbital calculations.

  7. ALMA IMAGING OF HCN, CS, AND DUST IN ARP 220 AND NGC 6240

    SciTech Connect

    Scoville, Nick; Manohar, Swarnima; Murchikova, Lena; Sheth, Kartik; Walter, Fabian; Zschaechner, Laura; Yun, Min; Koda, Jin; Sanders, David; Barnes, Joshua; Thompson, Todd; Robertson, Brant; Tacconi, Linda; Narayanan, Desika; Genzel, Reinhard; Davies, Richard; Hernquist, Lars; Brown, Robert; Hayward, Christopher C.; Kartaltepe, Jeyhan; and others

    2015-02-10

    We report ALMA Band 7 (350 GHz) imaging at 0.''4-0.''6 resolution and Band 9 (696 GHz) at ∼0.''25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 10{sup 9} M {sub ☉}within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are n{sub H{sub 2}}∼10{sup 5} cm{sup –3} at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n {sub H2} ∼ 2 × 10{sup 5} cm{sup –3}. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

  8. Adenine Synthesis in Interstellar Space: Mechanisms of Prebiotic Pyrimidine-Ring Formation of Monocyclic HCN-Pentamers

    NASA Astrophysics Data System (ADS)

    Glaser, Rainer; Hodgen, Brian; Farrelly, Dean; McKee, Elliot

    2007-06-01

    The question whether the nucleobases can be synthesized in interstellar space is of fundamental significance in considerations of the origin of life. Adenine is formally the HCN pentamer, and experiments have demonstrated that adenine is formed under certain conditions by HCN pentamerization in gas, liquid, and condensed phases. Most mechanistic proposals invoke the intermediacy of the HCN tetramer AICN (4), and it is thought that adenine synthesis is completed by addition of the 5th HCN to 4 to form amidine 5 and subsequent pyrimidine cyclization. In this context, we have been studying the mechanism for prebiotic pyrimidine-ring formation of monocyclic HCN-pentamers with ab initio electronic structure theory. The calculations model gas phase chemistry, and the results primarily inform discussions of adenine synthesis in interstellar space. Purine formation requires tautomerization of 5 to the conjugated amidine 6 (via hydrogen-tunneling, thermally with H+ -catalysis, or by photolysis) or to keteneimine 7 (by photolysis). It was found that 5-(N'-formamidinyl)-1H-imidazole-4-carbonitrile (6) can serve as a substrate for proton-catalyzed purine formation under photolytic conditions and N-(4-(iminomethylene)-1H-imidazol-5(4H)-ylidene)formamidine (7) can serve as a substrate for uncatalyzed purine formation under photolytic conditions. The absence of any sizeable activation barrier for the cyclization of 7 to the (Z)-imino form of 9H-adenine (Z)-2 is quite remarkable, and it is this feature that allows for the formation of the purine skeleton from 7 without any further activation.

  9. D2 dopamine receptors modulate neuronal resonance in subthalamic nucleus and cortical high-voltage spindles through HCN channels.

    PubMed

    Yang, Chen; Yan, Zhiqiang; Zhao, Bo; Wang, Julei; Gao, Guodong; Zhu, Junling; Wang, Wenting

    2016-06-01

    The high-voltage spindles (HVSs), one of the characteristic oscillations that include theta frequencies in the basal ganglia (BG)-cortical system, are involved in immobile behavior and show increasing power in Parkinson's disease (PD). Our previous results suggested that the D2 dopamine receptor might be involved in HVSs modulations in a rat model of PD. Membrane resonance is one of the cellular mechanisms of network oscillation; therefore, we investigated how dopamine modulates the theta frequency membrane resonance of neurons in the subthalamic nucleus (STN), a central pacemaker of BG, and whether such changes in STN neurons subsequently alter HVSs in the BG-cortical system. In particular, we tested whether dopamine modulates HVSs through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels-dependent membrane resonance in STN neurons. We found that an antagonist of D2 receptors, but not of D1 receptors, inhibited membrane resonance and HCN currents of STN neurons through a G-protein activity in acute brain slices. Our further in vivo experiments using local injection of a D2 receptor antagonist or an HCN blocker in STNs of free-moving rats showed an increase in HVSs power and correlation in the BG-cortical system. Local injection of lamotrigine, an HCN agonist, counteracted the effect induced by the D2 antagonist. Taken together, our results revealed a potential cellular mechanism underlying HVSs activity modulation in the BG-cortical system, i.e. tuning HCN activities in STN neurons through dopamine D2 receptors. Our findings might lead to a new direction in PD treatment by providing promising new drug targets for HVSs activity modulation. PMID:26808313

  10. The effects of HCN and KLT ion channels on adaptation and refractoriness in a stochastic auditory nerve model.

    PubMed

    Negm, Mohamed H; Bruce, Ian C

    2014-11-01

    An accurate model of auditory nerve fibers (ANFs) may assist in developing improved cochlear implant (CI) stimulation strategies. Previous studies have shown that the original Hodgkin-Huxley (HH) model may be better at describing nodes of Ranvier in ANFs than models for other mammalian axon types. However, the HH model is still unable to explain a number of phenomena observed in auditory nerve responses to CI stimulation such as adaptation to high-rate stimulation and the time course of relative refractoriness. Recent physiological investigations of ANFs have shown the presence of a number of ion channel types not considered in the previous modeling studies, including low-threshold potassium (KLT) channels and hyperpolarization-activated cation (HCN) channels. In this paper, we investigate inclusion of these ion channel types in a stochastic HH model of a single node of Ranvier. Simulation results for pulse trains with rates of 200, 800, and 2000 pulse/s suggests that both the KLT channels and HCN channels can produce adaptation in the spike rate. However, the adaptation due to KLT is restricted to higher stimulation rates, whereas the adaptation due to HCN is observed across all stimulation rates. Additionally, using pulse pairs it was found that KLT increased both the absolute and the relative refractory periods. HCN on its own increased just the relative refractory period, but produced a synergistic increase in the absolute refractory period when combined with KLT. Together these results argue strongly for the need to consider HCN and KLT channels when studying CI stimulation of ANFs. PMID:24893366

  11. Functional roles of Cav1.3, Cav3.1 and HCN channels in automaticity of mouse atrioventricular cells

    PubMed Central

    Marger, Laurine; Mesirca, Pietro; Alig, Jacqueline; Torrente, Angelo; Dubel, Stefan; Engeland, Birgit; Kanani, Sandra; Fontanaud, Pierre; Striessnig, Jörg; Shin, Hee-Sup; Isbrandt, Dirk; Ehmke, Heimo; Nargeot, Joël

    2011-01-01

    The atrioventricular node controls cardiac impulse conduction and generates pacemaker activity in case of failure of the sino-atrial node. Understanding the mechanisms of atrioventricular automaticity is important for managing human pathologies of heart rate and conduction. However, the physiology of atrioventricular automaticity is still poorly understood. We have investigated the role of three key ion channel-mediated pacemaker mechanisms namely, Cav1.3, Cav3.1 and HCN channels in automaticity of atrioventricular node cells (AVNCs). We studied atrioventricular conduction and pacemaking of AVNCs in wild-type mice and mice lacking Cav3.1 (Cav3.1−/−), Cav1.3 (Cav1.3−/−), channels or both (Cav1.3−/−/Cav3.1−/−). The role of HCN channels in the modulation of atrioventricular cells pacemaking was studied by conditional expression of dominant-negative HCN4 channels lacking cAMP sensitivity. Inactivation of Cav3.1 channels impaired AVNCs pacemaker activity by favoring sporadic block of automaticity leading to cellular arrhythmia. Furthermore, Cav3.1 channels were critical for AVNCs to reach high pacemaking rates under isoproterenol. Unexpectedly, Cav1.3 channels were required for spontaneous automaticity, because Cav1.3−/− and Cav1.3−/−/Cav3.1−/− AVNCs were completely silent under physiological conditions. Abolition of the cAMP sensitivity of HCN channels reduced automaticity under basal conditions, but maximal rates of AVNCs could be restored to that of control mice by isoproterenol. In conclusion, while Cav1.3 channels are required for automaticity, Cav3.1 channels are important for maximal pacing rates of mouse AVNCs. HCN channels are important for basal AVNCs automaticity but do not appear to be determinant for β-adrenergic regulation. PMID:21406960

  12. Preparation, characterization of LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} film cathode.

    SciTech Connect

    Kang, S. H.; Abraham, D. P.; Chemical Engineering

    2006-01-01

    Positive electrodes based on the LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} material are being evaluated in high-power lithium-ion cells for hybrid-electric vehicle applications. To determine performance degradation mechanisms that are associated with the active material, we prepared carbon- and binder-free LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} film cathode on a Pt substrate using a sol-gel spin coating technique. The material was characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Initial data from cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy measurements conducted on the electrodes are reported.

  13. THE BOLOCAM GALACTIC PLANE SURVEY. XII. DISTANCE CATALOG EXPANSION USING KINEMATIC ISOLATION OF DENSE MOLECULAR CLOUD STRUCTURES WITH {sup 13}CO(1-0)

    SciTech Connect

    Ellsworth-Bowers, Timothy P.; Glenn, Jason; Rosolowsky, Erik; Ginsburg, Adam; Evans II, Neal J.; Battersby, Cara; Shirley, Yancy L.; Svoboda, Brian

    2015-01-20

    We present an expanded distance catalog for 1710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO{sup +}(3-2), NH{sub 3}(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey (GRS) {sup 13}CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region of the GRS {sup 13}CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of {sup 13}CO matched to the BGPS source. For objects with a HCO{sup +}(3-2) velocity, ≈95% of the new {sup 13}CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and H II regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties ≲ 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centaurus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.

  14. The Bolocam Galactic Plane Survey. XII. Distance Catalog Expansion Using Kinematic Isolation of Dense Molecular Cloud Structures with 13CO(1-0)

    NASA Astrophysics Data System (ADS)

    Ellsworth-Bowers, Timothy P.; Rosolowsky, Erik; Glenn, Jason; Ginsburg, Adam; Evans, Neal J., II; Battersby, Cara; Shirley, Yancy L.; Svoboda, Brian

    2015-01-01

    We present an expanded distance catalog for 1710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO^+(3-2), NH3(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey (GRS) 13CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region of the GRS 13CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of 13CO matched to the BGPS source. For objects with a HCO^+(3-2) velocity, ≈95% of the new 13CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and H II regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties <~ 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centaurus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.

  15. Resolving the Bright HCN(1-0) Emission toward the Seyfert 2 Nucleus of M51: Shock Enhancement by Radio Jets and Weak Masing by Infrared Pumping?

    NASA Astrophysics Data System (ADS)

    Matsushita, Satoki; Trung, Dinh-V.-; Boone, Frédéric; Krips, Melanie; Lim, Jeremy; Muller, Sebastien

    2015-01-01

    We present high angular resolution observations of the HCN(1-0) emission (at ~1'' or ~34 pc), together with CO J = 1-0, 2-1, and 3-2 observations, toward the Seyfert 2 nucleus of M51 (NGC 5194). The overall HCN(1-0) distribution and kinematics are very similar to that of the CO lines, which have been indicated as the jet-entrained molecular gas in our past observations. In addition, high HCN(1-0)/CO(1-0) brightness temperature ratio of about unity is observed along the jets, similar to that observed at the shocked molecular gas in our Galaxy. These results strongly indicate that both diffuse and dense gases are entrained by the jets and outflowing from the active galactic nucleus. The channel map of HCN(1-0) at the systemic velocity shows a strong emission right at the nucleus, where no obvious emission has been detected in the CO lines. The HCN(1-0)/CO(1-0) brightness temperature ratio at this region reaches >2, a value that cannot be explained considering standard physical/chemical conditions. Based on our calculations, we suggest infrared pumping and possibly weak HCN masing, but still requiring an enhanced HCN abundance for the cause of this high ratio. This suggests the presence of a compact dense obscuring molecular gas in front of the nucleus of M51, which remains unresolved at our ~1'' (~34 pc) resolution, and consistent with the Seyfert 2 classification picture.

  16. Fractional factorial study of HCN removal over a 0.5% Pt/Al₂O₃ catalyst: effects of temperature, gas flow rate, and reactant partial pressure

    SciTech Connect

    Zhao, Haibo; Tonkyn, Russell G.; Barlow, Stephan E.; Peden, Charles HF.; Koel, Bruce E.

    2006-01-07

    Fractional factorial design was used to determine which factors have significant effects on the HCN (hydrogen cyanide) oxidation reaction over 0.5% Pt/Al?O? under lean conditions. We conclude that the reaction temperature and gas-hourly space velocity (GHSV) have significant effects on the HCN conversion, while no significant effects are caused by the presence of either NO (nitric oxide) or C?H? (propene). A central composite design was used to study the effects of temperature and GHSV on HCN conversion, C?H? conversion and NOx selectivity. Based on a second polynomial equation model, regression analysis was used to study the significance of each variable term and derive equations for each response. Our results show that HCN conversion was significantly affected by temperature (X3), GHSV (X4), a temperature polynomial term (X32), and a temperature and GHSV interaction term (X3X4). HCN conversion decreased with increasing values of GHSV and increased with increasing temperature, up to a transition temperature that depends on the GHSV value. The variables of temperature (X3), GHSV (X4), and the temperature polynomial term (X32) have significant effects on both C?H? conversion and NOx selectivity, but in these two cases the interaction of temperature and GHSV was not significant. Contour plots of HCN conversion, C?H? conversion, and NOx selectivity versus temperature and GHSV were constructed from an analysis of the measured data, and these plots can be utilized to estimate HCN conversion, C?H? conversion, and NOx selectivity over the range of temperatures and GHSV investigated. Optimum catalyst operation is described by high HCN conversion and low NOx selectivity. These results show C and o that the highest HCN conversion was achieved at temperatures above 250 relatively low GHSV values, while low NOx selectivity was best achieved at a C.o temperature of 215

  17. Airborne measurements of CO2, CH4 and HCN in boreal biomass burning plumes

    NASA Astrophysics Data System (ADS)

    O'Shea, Sebastian J.; Bauguitte, Stephane; Muller, Jennifer B. A.; Le Breton, Michael; Archibald, Alex; Gallagher, Martin W.; Allen, Grant; Percival, Carl J.

    2013-04-01

    Biomass burning plays an important role in the budgets of a variety of atmospheric trace gases and particles. For example, fires in boreal Russia have been linked with large growths in the global concentrations of trace gases such as CO2, CH4 and CO (Langenfelds et al., 2002; Simpson et al., 2006). High resolution airborne measurements of CO2, CH4 and HCN were made over Eastern Canada onboard the UK Atmospheric Research Aircraft FAAM BAe-146 from 12 July to 4 August 2011. These observations were made as part of the BORTAS project (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites). Flights were aimed at transecting and sampling the outflow from the commonly occurring North American boreal forest fires during the summer months and to investigate and identify the chemical composition and evolution of these plumes. CO2 and CH4 dry air mole fractions were determined using an adapted system based on a Fast Greenhouse Gas Analyser (FGGA, Model RMT-200) from Los Gatos Research Inc, which uses the cavity enhanced absorption spectroscopy technique. In-flight calibrations revealed a mean accuracy of 0.57 ppmv and 2.31 ppbv for 1 Hz observations of CO2 and CH4, respectively, during the BORTAS project. During these flights a number of fresh and photochemically-aged plumes were identified using simultaneous HCN measurements. HCN is a distinctive and useful marker for forest fire emissions and it was detected using chemical ionisation mass spectrometry (CIMS). In the freshest plumes, strong relationships were found between CH4, CO2 and other tracers for biomass burning. From this we were able to estimate that 8.5 ± 0.9 g of CH4 and 1512 ± 185 g of CO2 were released into the atmosphere per kg of dry matter burnt. These emission factors are in good agreement with estimates from previous studies and can be used to calculate budgets for the region. However for aged plumes the correlations between CH4 and other

  18. Selective Modulation of Histaminergic Inputs on Projection Neurons of Cerebellum Rapidly Promotes Motor Coordination via HCN Channels.

    PubMed

    Zhang, Jun; Zhuang, Qian-Xing; Li, Bin; Wu, Guan-Yi; Yung, Wing-Ho; Zhu, Jing-Ning; Wang, Jian-Jun

    2016-03-01

    Insights into function of central histaminergic system, a general modulator originating from the hypothalamus for whole brain activity, in motor control are critical for understanding the mechanism underlying somatic-nonsomatic integration. Here, we show a novel selective role of histamine in the cerebellar nuclei, the final integrative center and output of the cerebellum. Histamine depolarizes projection neurons but not interneurons in the cerebellar nuclei via the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels coupled to histamine H2 receptors, which are exclusively expressed on glutamatergic and glycinergic projection neurons. Furthermore, blockage of HCN channels to block endogenous histaminergic afferent inputs in the cerebellar nuclei significantly attenuates motor balance and coordination. Therefore, through directly and quickly modulation on projection neurons but not interneurons in the cerebellar nuclei, central histaminergic system may act as a critical biasing force to not only promptly regulate ongoing movement but also realize a rapid integration of somatic and nonsomatic response. PMID:25633097

  19. VizieR Online Data Catalog: AFGL 2591 maps in CS, SO and HCN lines (Benz+, 2007)

    NASA Astrophysics Data System (ADS)

    Benz, A. O.; Stauber, P.; Bourke, T. L.; van Det Tak, F. F. S.; van Dishoeck, E. F.; Jorgensen, J. K.

    2007-09-01

    The chemistry in the inner few thousand AU of accreting envelopes around young stellar objects is predicted to vary greatly with far-UV and X-ray irradiation by the central star. We search for molecular tracers of high-energy irradiation by the protostar in the hot inner envelope. The Submillimeter Array (SMA) has observed the high-mass star forming region AFGL 2591 in lines of CS, SO, HCN, HCN(nu2=1), and HC15N with 0.6" resolution at 350GHz probing radial scales of 600-3500AU for an assumed distance of 1kpc. The SMA observations are compared with the predictions of a chemical model fitted to previous single-dish observations. (2 data files).

  20. Ab initio calculation of a global potential, vibrational energies, and wave functions for HCN/HNC, and a simulation of the (A-tilde)-(X-tilde) emission spectrum

    NASA Technical Reports Server (NTRS)

    Bowman, Joel M.; Gazdy, Bela; Bentley, Joseph A.; Lee, Timothy J.; Dateo, Christopher E.

    1993-01-01

    A potential energy surface for the HCN/HNC system which is a fit to extensive, high-quality ab initio, coupled-cluster calculations is presented. All HCN and HNC states with energies below the energy of the first delocalized state are reported and characterized. Vibrational transition energies are compared with all available experimental data on HCN and HNC, including high CH-overtone states up to 23,063/cm. A simulation of the (A-tilde)-(X-tilde) stimulated emission pumping (SEP) spectrum is also reported, and the results are compared to experiment. Franck-Condon factors are reported for odd bending states of HCN, with one quantum of vibrational angular momentum, in order to compare with the recent assignment by Jonas et al. (1992), on the basis of axis-switching arguments of a number of previously unassigned states in the SEP spectrum.

  1. Increased expression of HCN2 channel protein in L4 dorsal root ganglion neurons following axotomy of L5- and inflammation of L4-spinal nerves in rats.

    PubMed

    Smith, T; Al Otaibi, M; Sathish, J; Djouhri, L

    2015-06-01

    A hallmark of peripheral neuropathic pain (PNP) is chronic spontaneous pain and/or hypersensitivity to normally painful stimuli (hyperalgesia) or normally nonpainful stimuli (allodynia).This pain results partly from abnormal hyperexcitability of dorsal root ganglion (DRG) neurons. We have previously shown, using a modified version of the lumbar 5 (L5)-spinal nerve ligation model of PNP (mSNA model involving L5-spinal nerve axotomy plus loose ligation of the lumbar 4 (L4)-spinal nerve with neuroinflammation-inducing chromic-gut), that L4 DRG neurons exhibit increased spontaneous activity, the key characteristic of neuronal hyperexcitability. The underlying ionic and molecular mechanisms of the hyperexcitability of L4 DRG neurons are incompletely understood, but could result from changes in expression and/or function of ion channels including hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are active near the neuron's resting membrane potential, and which produce an excitatory inward current that depolarizes the membrane potential toward the threshold of action potential generation. Therefore, in the present study we used the mSNA model to investigate whether: (a) expression of HCN1-HCN3 channels is altered in L4 DRG neurons which, in the mSNA model, are essential for transmission of the evoked pain, and which contribute to chronic spontaneous pain, and (b) local (intraplantar) blockade of these HCN channels, with a specific blocker, ZD7288, attenuates chronic spontaneous pain and/or evoked pain in mSNA rats. We found 7days after mSNA: (1) a significant increase in HCN2-immunoreactivity in small (<30μm) DRG neurons (predominantly IB4-negative neurons), and in the proportion of small neurons expressing HCN2 (putative nociceptors); (2) no significant change in HCN1- or HCN3-immunoreactivity in all cell types; and (3) attenuation, with ZD7288 (100μM intraplantar), of chronic spontaneous pain behavior (spontaneous foot lifting) and mechanical

  2. Energy yields for hydrogen cyanide and formaldehyde syntheses: the HCN and amino acid concentrations in the primitive ocean.

    PubMed

    Stribling, R; Miller, S L

    1987-01-01

    Prebiotic electric discharge and ultraviolet light experiments are usually reported in terms of carbon yields and involve a large input of energy to maximize yields. Experiments using lower energy inputs are more realistic prebiotic models and give energy yields which can be used to estimate the relative importance of the different energy sources on the primitive earth. Simulated prebiotic atmospheres containing either CH4, CO or CO2 with N2, H2O and variable amounts of H2 were subjected to the spark from a high frequency Tesla coil. The energy yields for the synthesis of HCN and H2CO were estimated. CH4 mixtures give the highest yields of HCN while H2CO is most efficiently produced with the CO mixtures. These results are a model for atmospheric corona discharges, which are more abundant than lightning and different in character. Preliminary experiments using artificial lightning are also reported. The energy yields from these experiments combined with the corona discharge available on the earth, allows a yearly production rate to be estimated. These are compared with other experiments and model calculations. From these production rates of HCN (e.g. 100 nmoles cm-2 yr-1) and the experimental hydrolysis rates, the steady state concentration in the primitive ocean can be calculated (e.g., 4 X 10(-6) M at pH 8 and 0 degrees). A steady state amino acid concentration of 3 X 10(-4) M is estimated from the HCN production rate and the rate of decomposition of the amino acids by passage through the submarine vents. PMID:2819806

  3. Reactivity of NH{sub 3} and HCN during low-grade fuel combustion in a swirling flow burner

    SciTech Connect

    Chunyang Wu; Dale Tree; Larry Baxter

    2007-07-01

    The experimentally measured major gas species profiles in the near-burner region provide insight on flame structure and pollutant formation mechanisms during pilot-scale biomass, coal, and biomass-coal cofiring tests. All tests involved separately metered but jointly fed coal and biomass in a variable-swirl burner. Locally fuel-rich regions form under overall fuel-lean conditions, as is typical of such flames, although there are no regions of the combustor that indicate average oxygen concentration reaches zero. The data strongly suggest that instantaneous oxygen concentrations reach zero, so the average finite values are indicative of turbulent intermittency between fuel-rich and fuel-lean eddies. Such intermittency impacts the entire flame structure in these and many previously published flames, though this feature may not be widely appreciated. Detectable HCN concentrations appear in the fuel-rich eddies in the coal-dominated flames with little or no detectable NH{sub 3}, whereas NH{sub 3} appears in the biomass-dominated flames with little or no detectable HCN. These data indicate that biomass predominantly forms NH{sub 3} whereas coal predominantly forms HCN as stable, fuel-rich, gas-phase compounds. Kinetics calculations demonstrate that NH{sub 3} has higher thermal stability and is more reactive within the flame front than HCN. Both species have similar conversion to NO at the same temperatures. The results confirm that NOx precursor formation depends on the parent fuel and form of nitrogen, at least for the coal and biomass fuels investigated here. 24 refs., 11 figs., 3 tabs.

  4. Role of Dynamics in the Autoinhibition and Activation of the Hyperpolarization-activated Cyclic Nucleotide-modulated (HCN) Ion Channels*♦

    PubMed Central

    VanSchouwen, Bryan; Akimoto, Madoka; Sayadi, Maryam; Fogolari, Federico; Melacini, Giuseppe

    2015-01-01

    The hyperpolarization-activated cyclic nucleotide-modulated (HCN) ion channels control rhythmicity in neurons and cardiomyocytes. Cyclic AMP allosterically modulates HCN through the cAMP-dependent formation of a tetrameric gating ring spanning the intracellular region (IR) of HCN, to which cAMP binds. Although the apo versus holo conformational changes of the cAMP-binding domain (CBD) have been previously mapped, only limited information is currently available on the HCN IR dynamics, which have been hypothesized to play a critical role in the cAMP-dependent gating of HCN. Here, using molecular dynamics simulations validated and complemented by experimental NMR and CD data, we comparatively analyze HCN IR dynamics in the four states of the thermodynamic cycle arising from the coupling between cAMP binding and tetramerization equilibria. This extensive set of molecular dynamics trajectories captures the active-to-inactive transition that had remained elusive for other CBDs, and it provides unprecedented insight on the role of IR dynamics in HCN autoinhibition and its release by cAMP. Specifically, the IR tetramerization domain becomes more flexible in the monomeric states, removing steric clashes that the apo-CDB structure would otherwise impose. Furthermore, the simulations reveal that the active/inactive structural transition for the apo-monomeric CBD occurs through a manifold of pathways that are more divergent than previously anticipated. Upon cAMP binding, these pathways become disallowed, pre-confining the CBD conformational ensemble to a tetramer-compatible state. This conformational confinement primes the IR for tetramerization and thus provides a model of how cAMP controls HCN channel gating. PMID:25944904

  5. GATING OF HCN CHANNELS BY CYCLIC NUCLEOTIDES: RESIDUE CONTACTS THAT UNDERLIE LIGAND BINDING, SELECTIVITY AND EFFICACY

    PubMed Central

    Zhou, Lei; Siegelbaum, Steven A.

    2007-01-01

    SUMMARY Cyclic nucleotides regulate the activity of various proteins by interacting with a conserved cyclic nucleotide-binding domain (CNBD). Although X-ray crystallographic studies have revealed the structures of several CNBDs, the residues responsible for generating the high efficacy with which ligand binding leads to protein activation remain unknown. Here we combine molecular dynamics simulations with mutagenesis to identify ligand contacts important for the regulation of the hyperpolarization-activated HCN2 channel by cyclic nucleotides. Surprisingly, out of seven residues that make strong contacts with ligand, only R632 in the C-helix of the CNBD is essential for high ligand efficacy, due to its selective stabilization of cNMP binding to the open state of the channel. Principle component analysis suggests that a local movement of the C-helix upon ligand binding propagates through the CNBD of one subunit to the C-linker of a neighboring subunit to apply force to the gate of the channel. PMID:17562313

  6. Structure and Energetics of Allosteric Regulation of HCN2 Ion Channels by Cyclic Nucleotides*

    PubMed Central

    DeBerg, Hannah A.; Brzovic, Peter S.; Flynn, Galen E.; Zagotta, William N.; Stoll, Stefan

    2016-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels play an important role in regulating electrical activity in the heart and brain. They are gated by the binding of cyclic nucleotides to a conserved, intracellular cyclic nucleotide-binding domain (CNBD), which is connected to the channel pore by a C-linker region. Binding of cyclic nucleotides increases the rate and extent of channel activation and shifts it to less hyperpolarized voltages. We probed the allosteric mechanism of different cyclic nucleotides on the CNBD and on channel gating. Electrophysiology experiments showed that cAMP, cGMP, and cCMP were effective agonists of the channel and produced similar increases in the extent of channel activation. In contrast, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) on the isolated CNBD indicated that the induced conformational changes and the degrees of stabilization of the active conformation differed for the three cyclic nucleotides. We explain these results with a model where different allosteric mechanisms in the CNBD all converge to have the same effect on the C-linker and render all three cyclic nucleotides similarly potent activators of the channel. PMID:26559974

  7. The rotational spectrum and properties of N2 ṡṡṡ HCN

    NASA Astrophysics Data System (ADS)

    Goodwin, Elizabeth J.; Legon, A. C.

    1985-05-01

    The ground state rotational spectra of eight isotopic species of a weakly bound dimer N(1)N(2) ṡṡṡ HCN(3) formed between molecular nitrogen and hydrogen cyanide have been detected and measured by the technique of pulsed-nozzle, Fourier-transform microwave spectroscopy. Rotational constants B0, centrifugal distortion constants DJ, and, where appropriate, nuclear quadrupole coupling constants χn(14N) and χ(D) have been determined. For the five isotopic species containing 14N nuclei the results are: An analysis of the B0 values shows that the equilibrium geometry is linear, or nearly so, with the nuclei in the order shown. The DJ values lead to kσ=2.39 N m-1 for the intermolecular stretching force constant while the difference χ1(14N)-χ2(14N) is interpreted in terms of a transfer of 0.016 e from N(1) to N(2) when the complex is formed in the zero-point state.

  8. Structure and Energetics of Allosteric Regulation of HCN2 Ion Channels by Cyclic Nucleotides.

    PubMed

    DeBerg, Hannah A; Brzovic, Peter S; Flynn, Galen E; Zagotta, William N; Stoll, Stefan

    2016-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels play an important role in regulating electrical activity in the heart and brain. They are gated by the binding of cyclic nucleotides to a conserved, intracellular cyclic nucleotide-binding domain (CNBD), which is connected to the channel pore by a C-linker region. Binding of cyclic nucleotides increases the rate and extent of channel activation and shifts it to less hyperpolarized voltages. We probed the allosteric mechanism of different cyclic nucleotides on the CNBD and on channel gating. Electrophysiology experiments showed that cAMP, cGMP, and cCMP were effective agonists of the channel and produced similar increases in the extent of channel activation. In contrast, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) on the isolated CNBD indicated that the induced conformational changes and the degrees of stabilization of the active conformation differed for the three cyclic nucleotides. We explain these results with a model where different allosteric mechanisms in the CNBD all converge to have the same effect on the C-linker and render all three cyclic nucleotides similarly potent activators of the channel. PMID:26559974

  9. Time series of 12CO and 13CO at northern mid-latitudes: determination of partial column and δ13C seasonal and interannual variations

    NASA Astrophysics Data System (ADS)

    Mahieu, E.; Duchatelet, P.; Rinsland, C. P.; Li, Q.; Boone, C. D.; Walker, K. A.; Bernath, P. F.; de Mazière, M.; Dils, B.

    2009-04-01

    Carbon monoxide (CO) is an important reactive gas in the troposphere. It is emitted at the ground level by fossil fuel combustion and biomass burning. Biogenic sources and oceans as well as oxidation of methane and nonmethane hydrocarbons complete the emissions budget. Large uncertainties still affect the relative contributions of the identified anthropogenic and natural sources. Destruction by the hydroxyl radical (OH) is the main removal process for CO in both the troposphere and the stratosphere. The resulting average tropospheric lifetime of CO varies from several weeks to a few months. Two approaches have been developed and optimized to independently retrieve abundances of 12CO and 13CO from high-resolution ground-based infrared solar spectra, using sets of carefully selected lines and the SFIT-2 (v3.91) algorithm which implements the optimal estimation method. The corresponding products will be described and characterized in terms of error budget and information content. These strategies have allowed us to produce partial column time series of 12CO and 13CO, using spectra recorded on a regular basis at the Jungfraujoch station (46.5°N, 8.0°E, 3580 m asl, Swiss Alps), a site of the Network for the Detection of Atmospheric Composition Change (NDACC). The seasonal and interannual changes observed in the12CO,13CO and δ13C (13C/12C) data sets will be presented and discussed. Complementary zonal mean time series derived from occultation measurements collected by the ACE-FTS instrument onboard the Canadian SCISAT-1 platform since 2004 will also be included and analyzed, focusing on the upper troposphere-lower stratosphere region of the atmosphere. Finally, we will use GEOS-Chem 3-D chemistry transport model results to help in the interpretation of the short- and long-term variations characterizing the ground-based and satellite data sets, focusing on the factors influencing the partitioning between the two CO isotopologues.

  10. Partitioning net ecosystem carbon exchange into net assimilation and respiration using 13CO2 measurements: A cost-effective sampling strategy

    NASA Astrophysics Data System (ADS)

    OgéE, J.; Peylin, P.; Ciais, P.; Bariac, T.; Brunet, Y.; Berbigier, P.; Roche, C.; Richard, P.; Bardoux, G.; Bonnefond, J.-M.

    2003-06-01

    The current emphasis on global climate studies has led the scientific community to set up a number of sites for measuring the long-term biosphere-atmosphere net CO2 exchange (net ecosystem exchange, NEE). Partitioning this flux into its elementary components, net assimilation (FA), and respiration (FR), remains necessary in order to get a better understanding of biosphere functioning and design better surface exchange models. Noting that FR and FA have different isotopic signatures, we evaluate the potential of isotopic 13CO2 measurements in the air (combined with CO2 flux and concentration measurements) to partition NEE into FR and FA on a routine basis. The study is conducted at a temperate coniferous forest where intensive isotopic measurements in air, soil, and biomass were performed in summer 1997. The multilayer soil-vegetation-atmosphere transfer model MuSICA is adapted to compute 13CO2 flux and concentration profiles. Using MuSICA as a "perfect" simulator and taking advantage of the very dense spatiotemporal resolution of the isotopic data set (341 flasks over a 24-hour period) enable us to test each hypothesis and estimate the performance of the method. The partitioning works better in midafternoon when isotopic disequilibrium is strong. With only 15 flasks, i.e., two 13CO2 nighttime profiles (to estimate the isotopic signature of FR) and five daytime measurements (to perform the partitioning) we get mean daily estimates of FR and FA that agree with the model within 15-20%. However, knowledge of the mesophyll conductance seems crucial and may be a limitation to the method.

  11. In-Situ Measurements of HCN and CH3CN In the Pacific Troposphere: Sources, Sinks, and Comparisons with Satellite Observations

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B.; Salas, L.; Herlth, D.; Viezee, W.; Jacob, D.; Blake, D.; Sachse, G.; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    A new capillary gas chromatographic method using a Reduction Gas Detector was developed to measure HCN and CH3CN in the remote troposphere. This instrumental configuration was deployed for the very first time in the Trace-P field mission performed during the spring of 2001. The NASA DC-8 aircraft afforded an opportunity to measure HCN and CH3CN in polluted and pristine environments over the Pacific to a maximum altitude of 12 km. These are some of the first in situ measurements of the distribution of HCN and CH3CN over the Pacific. Large background concentrations of both nitriles were found to be present and significant variability was observed. The abundance of HCN and CH3CN was strongly impacted by outflow of pollution from Asia. In general there appeared to be a direct but nonlinear relationship between the mixing ratios of HCN and CH3CN. The vertical structure of these chemicals shows direct evidence of the presence of a significant oceanic sink. These observations will be compared with the column content HCN data from satellites and other available measurements. A large body of data have been collected and are being analyzed, both statistically and with the help of models, to better understand the sources and sinks of these nitriles. These results will be presented.

  12. ALMA DETECTION OF THE VIBRATIONALLY EXCITED HCN J = 4-3 EMISSION LINE IN THE AGN-HOSTING LUMINOUS INFRARED GALAXY IRAS 20551–4250

    SciTech Connect

    Imanishi, Masatoshi; Nakanishi, Kouichiro

    2013-10-01

    We present results from our ALMA Cycle 0 observations, at the frequencies around the HCN, HCO{sup +}, and HNC J = 4-3 transition lines, of the luminous infrared galaxy IRAS 20551–4250 at z = 0.043, which is known to host an energetically important obscured active galactic nucleus (AGN). In addition to the targeted HCN, HCO{sup +}, and HNC J = 4-3 emission lines, two additional strong emission lines are seen, which we attribute to H{sub 2}S and CH{sub 3}CN(+CCH). The HCN-to-HCO{sup +} J = 4-3 flux ratio (∼0.7) is higher than in the other starburst-dominated galaxy (∼0.2) observed in our ALMA Cycle 0 program. We tentatively (∼5σ) detected the vibrationally excited (v {sub 2} = 1) HCN J = 4-3 (l = 1f) emission line, which is important for testing an infrared radiative pumping scenario for HCN. This is the second detection of this molecular transition in external galaxies. The most likely reason for this detection is not only the high flux of this emission line, but also the small molecular line widths observed in this galaxy, suggesting that vibrational excitation of HCN may be relatively common in AGN-hosting galaxies.

  13. Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two 13CO2 labelling techniques

    NASA Astrophysics Data System (ADS)

    Studer, M. S.; Siegwolf, R. T. W.; Abiven, S.

    2013-10-01

    Various 13CO2 labelling approaches exist to trace carbon (C) dynamics in plant-soil systems. However, it is not clear if the different approaches yield the same results. Moreover, there is no consistent way of data analysis to date. In this study we compare with the same experimental setup the two main techniques: the pulse and the continuous labelling. We evaluate how these techniques perform to estimate the C transfer velocity, the C partitioning along time and the C residence time in different plant-soil compartments. We used identical plant-soil systems (Populus deltoides x nigra, Cambisol soil) to compare the pulse labelling approach (exposure to 99 atom% 13CO2 for three hours, traced for eight days) with a continuous labelling (exposure to 10 atom% 13CO2, traced for 14 days). The experiments were conducted in climate chambers under controlled environmental conditions. Before label addition and at four successive sampling dates, the plant-soil systems were destructively harvested, separated into leaves, petioles, stems, cuttings, roots and soil and the microbial biomass was extracted from the soil. The soil CO2 efflux was sampled throughout the experiment. To model the C dynamics we used an exponential function to describe the 13C signal decline after pulse labelling. For the evaluation of the 13C distribution during the continuous labelling we suggest to use a logistic function. Pulse labelling is best suited to assess the maximum C transfer velocity from the leaves to other compartments. With continuous labelling, the mean transfer velocity through a compartment, including short-term storage pools, can be observed. The C partitioning between the plant-soil compartments was similar for both techniques, but the time of sampling had a large effect: shortly after labelling the allocation into leaves was overestimated and the soil 13CO2 efflux underestimated. The results of belowground C partitioning were consistent for the two techniques only after eight days of

  14. Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two 13CO2 labelling techniques

    NASA Astrophysics Data System (ADS)

    Studer, M. S.; Siegwolf, R. T. W.; Abiven, S.

    2014-03-01

    Various 13CO2 labelling approaches exist to trace carbon (C) dynamics in plant-soil systems. However, it is not clear if the different approaches yield the same results. Moreover, there is no consistent way of data analysis to date. In this study we compare with the same experimental setup the two main techniques: pulse and continuous labelling. We evaluate how these techniques perform to estimate the C transfer time, the C partitioning along time and the C residence time in different plant-soil compartments. We used identical plant-soil systems (Populus deltoides × nigra, Cambisol soil) to compare the pulse labelling approach (exposure to 99 atom % 13CO2 for three hours, traced for eight days) with a continuous labelling (exposure to 10 atom % 13CO2, traced for 14 days). The experiments were conducted in climate chambers under controlled environmental conditions. Before label addition and at four successive sampling dates, the plant-soil systems were destructively harvested, separated into leaves, petioles, stems, cuttings, roots and soil and soil microbial biomass was extracted. The soil CO2 efflux was sampled throughout the experiment. To model the C dynamics we used an exponential function to describe the 13C signal decline after pulse labelling. For the evaluation of the 13C distribution during the continuous labelling we applied a logistic function. Pulse labelling is best suited to assess the minimum C transfer time from the leaves to other compartments, while continuous labelling can be used to estimate the mean transfer time through a compartment, including short-term storage pools. The C partitioning between the plant-soil compartments obtained was similar for both techniques, but the time of sampling had a large effect: shortly after labelling the allocation into leaves was overestimated and the soil 13CO2 efflux underestimated. The results of belowground C partitioning were consistent for the two techniques only after eight days of labelling, when the

  15. Biogenic volatile organic compounds (BVOCs) emission of Scots pine under drought stress - a 13CO2 labeling study to determine de novo and pool emissions under different treatments

    NASA Astrophysics Data System (ADS)

    Lüpke, M.

    2015-12-01

    Plants emit biogenic volatile organic compounds (BVOCs) to e.g. communicate and to defend herbivores. Yet BVOCs also impact atmospheric chemistry processes, and lead to e.g. the built up of secondary organic aerosols. Abiotic stresses, such as drought, however highly influence plant physiology and subsequently BVOCs emission rates. In this study, we investigated the effect of drought stress on BVOCs emission rates of Scots pine trees, a de novo and pool emitter, under controlled climate chamber conditions within a dynamic enclosure system consisting of four plant chambers. Isotopic labeling with 13CO2 was used to detect which ratio of emissions of BVOCs derives from actual synthesis and from storage organs under different treatments. Additionally, the synthesis rate of the BVOCs synthesis can be determined. The experiment consisted of two campaigns (July 2015 and August 2015) of two control and two treated trees respectively in four controlled dynamic chambers simultaneously. Each campaign lasted for around 21 days and can be split into five phases: adaptation, control, dry-out, drought- and re-watering phase. The actual drought phase lasted around five days. During the campaigns two samples of BVOCs emissions were sampled per day and night on thermal desorption tubes and analyzed by a gas chromatograph coupled with a mass spectrometer and a flame ionization detector. Additionally, gas exchange of water and CO2, soil moisture, as well as leaf and chamber temperature was monitored continuously. 13CO2 labeling was performed simultaneously in all chambers during the phases control, drought and re-watering for five hours respectively. During the 13CO2 labeling four BVOCs emission samples per chamber were taken to identify the labeling rate on emitted BVOCs. First results show a decrease of BVOCs emissions during the drought phase and a recovery of emission after re-watering, as well as different strength of reduction of single compounds. The degree of labeling with 13

  16. Capacity improvement by deficit of transition metals in inverse spinel LiNi1/3Co1/3Mn1/3VO4 cathodes

    NASA Astrophysics Data System (ADS)

    Kitajou, Ayuko; Yoshida, Jun; Nakanishi, Shinji; Matsuda, Yasuaki; Kanno, Ryoji; Okajima, Toshihiro; Okada, Shigeto

    2016-01-01

    Although inverse spinel materials have attracted attention because of their unusually high voltage characteristics, their rechargeable capacities are generally less than 50 mAh g-1, as a result of the coexistence of Li and transition metal ions at 16d octahedral sites. This work attempted to improve cathode functioning by optimizing the quantities of Li and transition metal ions residing at the 16d sites of LiNi1/3Co1/3Mn1/3VO4. The rechargeable capacity of the LiNi0.28Co0.28Mn0.26V0.80O4 synthesized in the present study was found to be above 120 mAh g-1, representing the largest capacity reported to date for an inverse spinel material. The results of in-situ XANES analysis demonstrated that the charge-discharge reactions of LiNi1/3Co1/3Mn1/3VO4 corresponds to the Mn2+/Mn4+ and Co2+/Co3+ redox couples, mainly.

  17. 13CO2/12CO2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology

    NASA Astrophysics Data System (ADS)

    Stepanov, Eugene V.; Zyrianov, Pavel V.; Miliaev, Valerii A.; Selivanov, Yurii G.; Chizhevskii, Eugene G.; Os'kina, Svetlana; Ivashkin, Vladimir T.; Nikitina, Elena I.

    1999-07-01

    An analyzer of 13CO2/12CO2 ratio in exhaled air based on lead-salt tunable diode lasers is presented. High accuracy of the carbon isotope ratio detection in exhaled carbon dioxide was achieved with help of very simple optical schematics. It was based on the use of MBE laser diodes operating in pulse mode and on recording the resonance CO2 absorption at 4.2 micrometers . Special fast acquisition electronics and software were applied for spectral data collection and processing. Developed laser system was tested in a clinical train aimed to assessment eradication efficiency in therapy of gastritis associated with Helicobacter pylori infection. Data on the 13C-urea breath test used for P.pylori detection and obtained with tunable diode lasers in the course of the trail was compared with the results of Mass-Spectroscopy analysis and histology observations. The analyzer can be used also for 13CO2/12CO2 ratio detection in exhalation to perform gastroenterology breath test based on using other compounds labeled with stable isotopes.

  18. Effects of waterlogging on carbon assimilate partitioning in the Zoigê alpine wetlands revealed by 13CO2 pulse labeling

    PubMed Central

    Gao, Jun-Qin; Gao, Ju-Juan; Zhang, Xue-Wen; Xu, Xing-Liang; Deng, Zhao-Heng; Yu, Fei-Hai

    2015-01-01

    Waterlogging has been suggested to affect carbon (C) turnover in wetlands, but how it affects C allocation and stocks remains unclear in alpine wetlands. Using in situ 13CO2 pulse labelling, we investigated C allocation in both waterlogged and non-waterlogged sites in the Zoigê wetlands on the Tibetan Plateau in August 2011. More than 50% of total 13C fixed by photosynthesis was lost via shoot respiration. Shoots recovered about 19% of total 13C fixed by photosynthesis at both sites. Only about 26% of total fixed 13C was translocated into the belowground pools. Soil organic C pool accounted for 19% and roots recovered about 5–7% of total fixed 13C at both sites. Waterlogging significantly reduced soil respiration and very little 13C was lost via soil respiration in the alpine wetlands compared to that in grasslands. We conclude that waterlogging did not significantly alter C allocations among the C pools except the 13CO2 efflux derived from soil respiration and that shoots made similar contributions to C sequestration as the belowground parts in the Zoigê alpine wetlands. Therefore, changes in waterlogging due to climate change will not affect C assimilate partitioning but soil C efflux. PMID:25797457

  19. Unexpected high power performance of atomic layer deposition coated Li[Ni1/3Mn1/3Co1/3]O2 cathodes

    NASA Astrophysics Data System (ADS)

    Kim, Ji Woo; Travis, Jonathan J.; Hu, Enyuan; Nam, Kyung-Wan; Kim, Seul Cham; Kang, Chan Soon; Woo, Jae-Ha; Yang, Xiao-Qing; George, Steven M.; Oh, Kyu Hwan; Cho, Sung-Jin; Lee, Se-Hee

    2014-05-01

    Electric-powered transportation requires an efficient, low-cost, and safe energy storage system with high energy density and power capability. Despite its high specific capacity, the current commercially available cathode material for today's state-of-art Li-ion batteries, lithium nickel-manganese-cobalt oxide Li[Ni1/3 Mn1/3Co1/3]O2 (NMC), suffers from poor cycle life for high temperature operation and marginal rate capability resulting from irreversible degradation of the cathode material upon cycling. Using an atomic-scale surface engineering, the performance of Li[Ni1/3Mn1/3Co1/3]O2 in terms of rate capability and high temperature cycle-life is significantly improved. The Al2O3 coating deposited by atomic layer deposition (ALD) dramatically reduces the degradation in cell conductivity and reaction kinetics. This durable ultra-thin Al2O3-ALD coating layer also improves stability for the NMC at an elevated temperature (55 °C). The experimental results suggest that a highly durable and safe cathode material enabled by atomic-scale surface modification could meet the demanding performance and safety requirements of next-generation electric vehicles.

  20. Electric pulse current stimulation increases electrophysiological properties of If current reconstructed in mHCN4-transfected canine mesenchymal stem cells

    PubMed Central

    FENG, YUANYUAN; LUO, SHOUMING; YANG, PAN; SONG, ZHIYUAN

    2016-01-01

    The ‘funny’ current, also known as the If current, play a crucial role in the spontaneous diastolic depolarization of sinoatrial node cells. The If current is primarily induced by the protein encoded by the hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) gene. The functional If channel can be reconstructed in canine mesenchymal stem cells (cMSCs) transfected with mouse HCN4 (mHCN4). Biomimetic studies have shown that electric pulse current stimulation (EPCS) can promote cardiogenesis in cMSCs. However, whether EPCS is able to influence the properties of the If current reconstructed in mHCN4-transfected cMSCs remains unclear. The present study aimed to investigate the effects of EPCS on the If current reconstructed in mHCN4-transfected cMSCs. The cMSCs were transfected with the lentiviral vector pLentis-mHCN4-GFP. Following transfection, these cells were divided into two groups: mHCN4-transfected cMSCs (group A), and mHCN4-transfected cMSCs induced by EPCS (group B). Using a whole cell patch-clamp technique, the If current was recorded, and group A cMSCs showed significant time and voltage dependencies and sensitivity to extracellular Cs+. The half-maximal activation (V1/2) value was −101.2±4.6 mV and the time constant of activation was 324±41 msec under −160 mV. In the group B cells the If current increased obviously and activation curve moved to right. The absolute value of V1/2 increased significantly to −92.4±4.8 mV (P<0.05), and the time constant of activation diminished under the same command voltage (251±44 vs. 324±41, P<0.05). In addition, the mRNA and protein expression levels of HCN4, connexin 43 (Cx43) and Cx45 were upregulated in group B compared with group A, as determined by reverse transcription-quantitative polymerase chain reaction and western blot analyses. Transmission electron micrographs also confirmed the increased gap junctions in group B. Collectively, these results indicated that reconstructed If channels

  1. Diffuse and Dense Gas in Nearby Luminous Merging Galaxies

    NASA Astrophysics Data System (ADS)

    Saito, T.; Iono, D.; Ueda, J.; Yun, M. S.; Nakanishi, K.; Imanishi, M.; Hagiwara, Y.; Kaneko, H.; Komugi, S.; Espada, D.; Motohara, K.; Sugai, H.; Yamashita, T.; Tateuchi, K.; Lee, M.; Michiyama, T.; Kawabe, R.

    2015-12-01

    We present high resolution (0".2 - 2."0) ALMA cycle 2 observations of the IR-bright mid-stage merger VV 114 (band 3), the minor merger NGC 1614 (band 3/6), and the early-stage merger NGC 3110 (band 3), which are supplemented with the cycle 0 observations of VV 114 (band 3/7) and NGC 1614 (band 7/9). These observations include the CO (1-0), CO (2-1), 13CO (1-0), 13CO (2-1), CO (3-2), CO (6-5), HCN (4-3), and HCO+ (4-3) emission as well as continuum emission. We find that VV 114 has a multi-phase ISM (e.g., extended CO arms [˜ 10 kpc], a 13CO filament [˜ 6 kpc], and compact HCN sources [< 200 pc]), while NGC 1614 shows a rotating molecular ring with the radius of 240 pc, which is detected in the all molecular lines above. NGC 3110 shows two asymmetric molecular spiral arms and a strong bar. The CN (1-0), C18O (2-1), CS (2-1), and CH3OH (2-1) emission are also detected. Diagnosing detected lines using line intensity ratios, we suggest that an AGN, starbursts, and shocks are important drivers of the chemistry of VV 114, while merger and bar-induced starburst activities dominate the chemistry of NGC 1614 and NGC 3110, respectively.

  2. RESOLVING THE BRIGHT HCN(1–0) EMISSION TOWARD THE SEYFERT 2 NUCLEUS OF M51: SHOCK ENHANCEMENT BY RADIO JETS AND WEAK MASING BY INFRARED PUMPING?

    SciTech Connect

    Matsushita, Satoki; Trung, Dinh-V-; Boone, Frédéric; Krips, Melanie; Lim, Jeremy; Muller, Sebastien

    2015-01-20

    We present high angular resolution observations of the HCN(1-0) emission (at ∼1'' or ∼34 pc), together with CO J = 1-0, 2-1, and 3-2 observations, toward the Seyfert 2 nucleus of M51 (NGC 5194). The overall HCN(1-0) distribution and kinematics are very similar to that of the CO lines, which have been indicated as the jet-entrained molecular gas in our past observations. In addition, high HCN(1-0)/CO(1-0) brightness temperature ratio of about unity is observed along the jets, similar to that observed at the shocked molecular gas in our Galaxy. These results strongly indicate that both diffuse and dense gases are entrained by the jets and outflowing from the active galactic nucleus. The channel map of HCN(1-0) at the systemic velocity shows a strong emission right at the nucleus, where no obvious emission has been detected in the CO lines. The HCN(1-0)/CO(1-0) brightness temperature ratio at this region reaches >2, a value that cannot be explained considering standard physical/chemical conditions. Based on our calculations, we suggest infrared pumping and possibly weak HCN masing, but still requiring an enhanced HCN abundance for the cause of this high ratio. This suggests the presence of a compact dense obscuring molecular gas in front of the nucleus of M51, which remains unresolved at our ∼1'' (∼34 pc) resolution, and consistent with the Seyfert 2 classification picture.

  3. Influence of air-staging on the concentration profiles of NH{sub 3} and HCN in the combustion chamber of a CFB boiler burning coal

    SciTech Connect

    Kassman, H.; Karlsson, M.; Aamand, L.E.

    1999-07-01

    The characterization of the concentration profiles of NH{sub 3} and HCN are of great importance for increasing the knowledge of the formation and destruction pathways of NO and N{sub 2}O in a fluidized bed boiler. Further improvements of the sampling methods for the determination of both NH{sub 3} and HCN in the combustion chamber in full-scale CFB boilers are also needed. A gas-sampling probe connected to a Fourier Transform Infrared (FTIR) instrument and a gas-quenching (GQ) probe in which the sample is quenched directly in the probe tip by a circulating trapper solution were used. The FTIR technique is based on analysis of hot combustion gases, whereas the trapper solutions from the GQ probe were analyzed by means of wet chemistry. The tests were performed during coal combustion in a 12 MW CFB boiler, which was operated at three air-staging cases with the addition of limestone for sulfur capture. The concentration profiles of NH{sub 3} and HCN in the combustion chamber showed a different pattern concerning the influence of air-staging. The highest levels of NH{sub 3} were observed during reducing condition (severe air-staging), and the lowest were found under oxidizing conditions (no air-staging). The levels of HCN were much lower than those measured for NH{sub 3}. The highest levels of HCN were observed for reversed air-staging and severe air-staging showed almost no HCN. The potential reactors involving NH{sub 3} and HCN in the combustion chamber as well as the potential measurement errors in each sampling technique are discussed for the three air-staging cases.

  4. The Dense Gas in the Largest Molecular Complexes of the Antennae: HCN and HCO+ Observations of NGC 4038/39 Using ALMA

    NASA Astrophysics Data System (ADS)

    Schirm, Maximilien R. P.; Wilson, Christine D.; Madden, Suzanne C.; Clements, Dave L.

    2016-06-01

    We present observations of the dense molecular gas tracers {HCN}, {HNC}, and {{HCO}}+ in the J=1-0 transition using the Atacama Large Millimeter/submillimeter Array. We supplement our data sets with previous observations of {CO} J=1-0, which trace the total molecular gas content. We separate the Antennae into seven bright regions in which we detect emission from all three molecules, including the nuclei of NGC 4038 and NGC 4039, five super giant molecular complexes in the overlap region, and two additional bright clouds. We find that the ratio of {L}{HCN}/{L}{CO}, which traces the dense molecular gas fraction, is greater in the two nuclei ({L}{HCN}/{L}{CO} ∼ \\quad 0.07-0.08) than in the overlap region ({L}{HCN}/{L}{CO} \\lt 0.05). We attribute this to an increase in pressure due to the stellar potential within the nuclei; a similar effect to what has been seen previously in the Milky Way and nearby spiral galaxies. Furthermore, the ratio of {L}{HNC}/{L}{HCN} ∼ \\quad 0.3-0.4 does not vary by more than a factor of 1.5 between regions. By comparing our measured ratios to photon dominated region (PDR) models including mechanical heating, we find that the ratio of {L}{HNC}/{L}{HCN} is consistent with mechanical heating contributing ≳5%–10% of the PDR surface heating to the total heating budget. Finally, the ratio of {L}{HCN}/{L}{HCO+} varies from ∼1 in the nucleus of NGC 4038 down to ∼0.5 in the overlap region. The lower ratio in the overlap region may be due to an increase in the cosmic ray rate from the increased supernova rate within this region.

  5. Activation of mGluR1 contributes to neuronal hyperexcitability in the rat anterior cingulate cortex via inhibition of HCN channels.

    PubMed

    Gao, Shi-Hao; Wen, Hui-Zhong; Shen, Lin-Lin; Zhao, Yan-Dong; Ruan, Huai-Zhen

    2016-06-01

    Neuronal hyperexcitability in the anterior cingulate cortex (ACC) is considered as one of the most important pathological changes responsible for the chronification of neuropathic pain. However, the underlying mechanisms remain elusive. In the present study, we investigated the possible mechanisms using a rat model of chronic constriction injury (CCI) to the sciatic nerve. We found a substantial decrease in hyperpolarization-activated/cyclic nucleotide-gated (HCN) currents in layer 5 pyramidal neurons (L5 PNs) in ACC slices, which dramatically increased the excitability of these neurons. This effect could be mimicked in sham slices by activating group 1 metabotropic glutamate receptors, and be blocked in CCI slices by inhibiting metabotropic glutamate receptor subtype 1 (mGluR1). Next, the inhibition of HCN currents was reversed by a protein kinase C (PKC) inhibitor, followed by a reduced neuronal hyperexcitability. Furthermore, HCN channel subtype 1 (HCN1) level was significantly reduced after CCI, whereas mGluR1 level increased. These changes were mainly observed in L5 of the ACC, where HCN1 and mGluR1 were highly colocalized. For behavioral tests, intra-ACC microinjection of mGluR1-shRNA suppressed the CCI-induced behavioral hypersensitivity, particularly thermal hyperalgesia, but not aversive behavior, and this effect was attenuated by the pre-blockade of HCN channels. Taken together, the neuronal hyperexcitability of ACC L5 PNs likely results from an upregulation of mGluR1 and a downstream pathway involving PKC activation and a downregulation of HCN1 in the early phase of neuropathic pain. These alterations may at least in part contribute to the development of behavioral hypersensitivity in CCI rats. PMID:26829470

  6. Riverine GHG emissions: one year of CO2, 13CO2 and CH4 flux measurements on Vistula river in Krakow, southern Poland

    NASA Astrophysics Data System (ADS)

    Jasek, Alina; Wachniew, Przemyslaw; Zimnoch, Miroslaw

    2013-04-01

    Terrestrial surface waters are generally considered to be sources of carbon dioxide and methane, because respiration of organic matter via aerobic and anaerobic pathways causes supersaturation of surface waters with respect to CO2 and CH4, respectively. In rivers, these processes are influenced by such anthropogenic factors as changes of land-use, wastewater and alteration of river channels. The research object is Vistula, the largest Polish river. It has the length of 1047 km and annual runoff of 6.2x1010m3. The urban section of Vistula in Krakow receives large amounts of organic matter from highly urbanized catchment and point discharges of urban waste waters within the city limits. The river was sampled regularly at three points: the entrance to the city, the center and the point where Vistula leaves the agglomeration. A floating chamber coupled with Picarro G2101-i analyzer was applied to quantify CO2, 13CO2 and CH4 fluxes leaving the surface of the river. A floating chamber was equipped with sensors to measure air pressure, temperature and humidity inside the chamber and the temperature of water. The chamber was equipped with a set of floats and an anchor. The measurements started in October 2011, and were repeated with approximately monthly frequency. Physicochemical properties of water (temperature, conductivity, pH, CO2 partial pressure over the water surface and alkalinity) were also measured during each measurement campaign. In addition, at each site short-term variability of the measured fluxes was also investigated. Additionally, short-term variability of the measured fluxes of CO2, 13CO2 and CH4 were performed in all three sites. The results indicate that fluxes of CO2 released from the river are comparable with the soil emissions of this gas measured in Krakow area. The δ13CO2 signature of riverine CO2 flux allowed to identify decomposition of C3 organic matter as the major source of this gas. No distinct seasonal variability of the CO2 emission and

  7. Reversal of infall in SgrB2(M) revealed by Herschel/HIFI observations of HCN lines at THz frequencies

    NASA Astrophysics Data System (ADS)

    Rolffs, R.; Schilke, P.; Comito, C.; Bergin, E. A.; van der Tak, F. F. S.; Lis, D. C.; Qin, S.-L.; Menten, K. M.; Güsten, R.; Bell, T. A.; Blake, G. A.; Caux, E.; Ceccarelli, C.; Cernicharo, J.; Crockett, N. R.; Daniel, F.; Dubernet, M.-L.; Emprechtinger, M.; Encrenaz, P.; Gerin, M.; Giesen, T. F.; Goicoechea, J. R.; Goldsmith, P. F.; Gupta, H.; Herbst, E.; Joblin, C.; Johnstone, D.; Langer, W. D.; Latter, W. D.; Lord, S. D.; Maret, S.; Martin, P. G.; Melnick, G. J.; Morris, P.; Müller, H. S. P.; Murphy, J. A.; Ossenkopf, V.; Pearson, J. C.; Pérault, M.; Phillips, T. G.; Plume, R.; Schlemmer, S.; Stutzki, J.; Trappe, N.; Vastel, C.; Wang, S.; Yorke, H. W.; Yu, S.; Zmuidzinas, J.; Diez-Gonzalez, M. C.; Bachiller, R.; Martin-Pintado, J.; Baechtold, W.; Olberg, M.; Nordh, L. H.; Gill, J. J.; Chattopadhyay, G.

    2010-10-01

    Aims: To investigate the accretion and feedback processes in massive star formation, we analyze the shapes of emission lines from hot molecular cores, whose asymmetries trace infall and expansion motions. Methods: The high-mass star forming region SgrB2(M) was observed with Herschel/HIFI (HEXOS key project) in various lines of HCN and its isotopologues, complemented by APEX data. The observations are compared to spherically symmetric, centrally heated models with density power-law gradient and different velocity fields (infall or infall+expansion), using the radiative transfer code RATRAN. Results: The HCN line profiles are asymmetric, with the emission peak shifting from blue to red with increasing J and decreasing line opacity (HCN to H13CN). This is most evident in the HCN 12-11 line at 1062 GHz. These line shapes are reproduced by a model whose velocity field changes from infall in the outer part to expansion in the inner part. Conclusions: The qualitative reproduction of the HCN lines suggests that infall dominates in the colder, outer regions, but expansion dominates in the warmer, inner regions. We are thus witnessing the onset of feedback in massive star formation, starting to reverse the infall and finally disrupting the whole molecular cloud. To obtain our result, the THz lines uniquely covered by HIFI were critically important. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  8. Molecular dynamics in hydrogen-bonded interactions - A preliminary experimentally determined harmonic stretching force field for HCN---HF

    NASA Astrophysics Data System (ADS)

    Wofford, B. A.; Lieb, S. G.; Bevan, J. W.

    1987-10-01

    The anharmonicity constant X sub 11 is presently evaluated, and the anharmonicity-corrected fundamental frequency omega sub 1 is determined, on the basis of observations of the 2nu sub 1 overtone band in the hydrogen-bonded HNC---HF complex. These data are used in conjunction with rovibrational analyses in the common and perdeuterated isotopic species of HCN---HF to calculate an approximate stretching harmonic force. The results obtained are the basis of a quantitative assessment of the applicability of the Cummings and Wood (1974) approximation of this hydrogen-bonded complex, as well as of an estimate of the equilibrium distortion constant in the harmonic limit.

  9. Importance of solid fuel properties to nitrogen oxide formation through HCN and NH[sub 3] in small particle combustion

    SciTech Connect

    Aho, M.J.; Haemaelaeinen, J.P.; Tummavuori, J.L. Univ. of Jyvaeskylae . Dept. of Chemistry)

    1993-10-01

    The formation of nitrogen oxides from fuel-nitrogen through intermediates was studied by measuring first fuel-O/fuel-N ratios and nitrogen functionality in selected solid fuels. Then the ratios of the yields (fuel-N [r arrow] HCN)/(fuel-N [r arrow] NH[sub 3]) in a nearly inert atmosphere at 800 C in an entrained flow reactor was measured and finally the ratio (fuel-N [r arrow] N[sub 2]O)/(fuel-N [r arrow] NO) in an oxidizing atmosphere at 800 C The fuels studied were coal, brown coal, S- and C-type peat, fir bark, birch bark and pine bark, all milled to a particle size < 63[mu]m. The ratios of O/N in the fuel, measured by elemental analysis, ranged from 7 to 150. Nitrogen functionality (mass percent of the total nitrogen content) was determined by XPS. the (fuel-N [r arrow] HCN)/(fuel-N [r arrow] NH[sub 3]) conversion ratio in the absence of O[sub 2], and also the (fuel-N [r arrow] N[sub 2]O)/(fuel-N [r arrow] NO) conversion ratio with O[sub 2] present, decreased with increasing ratio of fuel-O/fuel-N, but neither ratio decreased regularly with the increasing ratio of pyrrolic to pyridinic nitrogen in the fuel. Thus, fuel-oxygen plays a more important role than nitrogen functionality in the chemistry of nitrogen oxide formation. The strong effect of (fuel-O/fuel-N) ratio on the (fuel-N [r arrow] HCN)/(fuel-N [r arrow] NH[sub 3]) ratio may be due to the reaction between OH radicals and HCN to form NH[sub 3] near the fuel particle. The importance of this reaction is considered. Charring the fuel sample before combustion led to a sharp drop in the conversion of fuel-N to N[sub 2]O compared with the virgin fuels. Thus, heterogeneous combustion reactions produced much less N[sub 2]O than homogeneous combustion reactions.

  10. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    NASA Astrophysics Data System (ADS)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  11. Probing the outer atmosphere of carbon stars - C2H2, HCN and C3 features in the SWS range

    NASA Astrophysics Data System (ADS)

    Loidl, R.; Hron, J.; Jorgensen, U. G.; Höfner, S.

    2000-11-01

    We have obtained ISO-SWS spectra of a number of carbon-rich AGB stars in the wavelength range 2.4 - 44 μm with a resolution of about 400. We compare these spectra with results of hydrostatic and dynamic model atmospheres. Of special interest are the features which are formed far out in the atmosphere like the C2H2, HCN and C3 features. For these outer regions of the atmosphere deviations from hydrostatic structures are to be expected.

  12. Precise 13CO2/12CO2 isotopic ratio measurements for breath diagnosis with a 2-μm diode laser

    NASA Astrophysics Data System (ADS)

    Sun, Mingguo; Ma, Hongliang; Cao, Zhensong; Liu, Kun; Wang, Guishi; Wang, Lei; Liu, Qiang; Gao, Xiaoming

    2014-11-01

    A laser spectrometer based on a distributed-feedback semiconductor diode laser at 2 μm is developed to measure the changes of 13CO2/12CO2 isotope ratio in exhaled breath sample with the CO2 concentration of ~4%. It is characterized by a simplified optical layout, in which a single detector and associated electronics are used to probe CO2 spectrum. The cell has 10 cm long base length with 26.4 m optical path length in total and 330 cm3 volume. The cell pressure and temperature are controlled at 50 Torr and 28°, respectively. The best 13δ precision of 0.06‰ was achieved by using wavelet denoising and Kalman filter.

  13. Determination of de novo and pool emissions of terpenes from four common boreal/alpine trees by 13CO2 labelling and PTR-MS analysis.

    PubMed

    Ghirardo, Andrea; Koch, Kristine; Taipale, Risto; Zimmer, Ina; Schnitzler, Jörg-Peter; Rinne, Janne

    2010-05-01

    Boreal forests emit a large amount of monoterpenes into the atmosphere. Traditionally these emissions are assumed to originate as evaporation from large storage pools. Thus, their diurnal cycle would depend mostly on temperature. However, there is indication that a significant part of the monoterpene emission would originate directly from de novo synthesis. By applying 13CO2 fumigation and analyzing the isotope fractions with proton transfer reaction mass spectrometry (PTR-MS) and classical GC-MS, we determined the fractions of monoterpene emissions originating from de novo biosynthesis in Pinus sylvestris (58%), Picea abies (33.5%), Larix decidua (9.8%) and Betula pendula (100%). Application of the observed split between de novo and pool emissions from P. sylvestris in a hybrid emission algorithm resulted in a better description of ecosystem scale monoterpene emissions from a boreal Scots pine forest stand. PMID:20040067

  14. 3-D dumbbell-like LiNi1/3Mn1/3Co1/3O2 cathode materials assembled with nano-building blocks for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ryu, Won-Hee; Lim, Sung-Jin; Kim, Won-Keun; Kwon, HyukSang

    2014-07-01

    Dumbbell-like microsphere carbonate precursors including multi-transition metal components (Ni1/3Mn1/3Co1/3CO3) assembled with nano-building blocks were synthesized by urea-assisted solvo/hydrothermal method, and layered cathode materials (LiNi1/3Mn1/3Co1/3O2) were subsequently prepared using the similarly shaped carbonate precursors for Li-ion batteries. For the synthesis of hierarchical microsphere structures, the partial addition of viscous organic solvent (e.g. ethylene glycol) in aqueous solution played a crucial role, not only in suppressing the sudden particle growth but also in regulating the directional crystallization of carbonate particles on the surface. The dumbbell-like LiNi1/3Mn1/3Co1/3O2 assembled with nanocubes prepared via the urea-assisted solvo/hydrothermal method exhibited better electrochemical characteristics, such as initial discharge capacity, cyclic performance, and rate-capability as a cathode material of Li-ion batteries, compared with the LiNi1/3Mn1/3Co1/3O2 materials prepared via the conventional co-precipitation method.

  15. In-Situ Measurements of HCN and CH3CN in the Pacific Troposphere: Sources, Sinks, and Comparisons with Spectroscopic Observations

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B.; Salas, L.; Herlth, D.; Czech, E.; Viezee, W.; Li, Q.; Jacob, D. J.; Blake, D.; Sachse, G.; Harward, C. N.; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    We report the first in-situ measurements of hydrogen cyanide (HCN) and acetonitrile (CH3CN) from the Pacific troposphere (0-12 km) obtained during the NASA/Trace-P mission (Feb.-April, 2001). Mean HCN and CH3CN mixing ratios of 243 (+/-118) ppt and 149 (+/-56) ppt respectively, were measured. The in-situ observations correspond to a total HCN column of 4.4-4.9 x 10(exp 15) molec. cm(exp -2) and a CH3CN column of 2.8-3.0 x 10(exp 15) molec. cm(exp -2). This HCN column is in good agreement with available spectroscopic observations. The atmospheric concentrations of HCN and CH3CN were greatly influenced by outflow of pollution from Asia. There is a linear relationship between the mixing ratios of HCN and CH3CN, and in turn these are well correlated with tracers of biomass combustion (e.g. CH3Cl, CO). Relative enhancements with respect to known tracers of biomass combustion within selected plumes in the free troposphere, and pollution episodes in the boundary layer allow an estimation of a global biomass burning source of 0.8+/-0.4 Tg (N)/y for HCN and 0.4+/-0.1 Tg (N)/y for CH3CN. In comparison, emissions from automobiles and industry are quite small (<0.05 Tg (N)/y). The vertical structure of HCN and CH3CN indicated reduced mixing ratios in the MBL (Marine Boundary Layer). Using, a simple box model, the observed gradients across the top of the MBL are used to derive an oceanic flux of 6.7 x 10(exp -15) g (N) cm(exp -2)/s for HCN and 4.8 x 10(exp -15) g (N) cm(exp -2)/s for CH3CN. An air-sea exchange model is used to conclude that this flux can be maintained if the oceans are under-saturated in HCN and CH3CN by 23% and 17%, respectively. It is inferred that oceanic loss is a dominant sink for these nitrites, and they deposit some 1.3 Tg (N) of nitrogen annually to the oceans. Assuming reaction with OH radicals and loss to the oceans as the major removal processes, a mean atmospheric residence time of 4.7 months for HCN and 5.1 months for CH3CN is calculated. A global

  16. 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.

  17. Reduction of nitrogen compounds in oceanic basement and its implications for HCN formation and abiotic organic synthesis

    PubMed Central

    2009-01-01

    Hydrogen cyanide is an excellent organic reagent and is central to most of the reaction pathways leading to abiotic formation of simple organic compounds containing nitrogen, such as amino acids, purines and pyrimidines. Reduced carbon and nitrogen precursor compounds for the synthesis of HCN may be formed under off-axis hydrothermal conditions in oceanic lithosphere in the presence of native Fe and Ni and are adsorbed on authigenic layer silicates and zeolites. The native metals as well as the molecular hydrogen reducing CO2 to CO/CH4 and NO3-/NO2- to NH3/NH4+ are a result of serpentinization of mafic rocks. Oceanic plates are conveyor belts of reduced carbon and nitrogen compounds from the off-axis hydrothermal environments to the subduction zones, where compaction, dehydration, desiccation and diagenetic reactions affect the organic precursors. CO/CH4 and NH3/NH4+ in fluids distilled out of layer silicates and zeolites in the subducting plate at an early stage of subduction will react upon heating and form HCN, which is then available for further organic reactions to, for instance, carbohydrates, nucleosides or even nucleotides, under alkaline conditions in hydrated mantle rocks of the overriding plate. Convergent margins in the initial phase of subduction must, therefore, be considered the most potent sites for prebiotic reactions on Earth. This means that origin of life processes are, perhaps, only possible on planets where some kind of plate tectonics occur. PMID:19849830

  18. Reduction of nitrogen compounds in oceanic basement and its implications for HCN formation and abiotic organic synthesis.

    PubMed

    Holm, Nils G; Neubeck, Anna

    2009-01-01

    Hydrogen cyanide is an excellent organic reagent and is central to most of the reaction pathways leading to abiotic formation of simple organic compounds containing nitrogen, such as amino acids, purines and pyrimidines. Reduced carbon and nitrogen precursor compounds for the synthesis of HCN may be formed under off-axis hydrothermal conditions in oceanic lithosphere in the presence of native Fe and Ni and are adsorbed on authigenic layer silicates and zeolites. The native metals as well as the molecular hydrogen reducing CO2 to CO/CH4 and NO3-/NO2- to NH3/NH4+ are a result of serpentinization of mafic rocks. Oceanic plates are conveyor belts of reduced carbon and nitrogen compounds from the off-axis hydrothermal environments to the subduction zones, where compaction, dehydration, desiccation and diagenetic reactions affect the organic precursors. CO/CH4 and NH3/NH4+ in fluids distilled out of layer silicates and zeolites in the subducting plate at an early stage of subduction will react upon heating and form HCN, which is then available for further organic reactions to, for instance, carbohydrates, nucleosides or even nucleotides, under alkaline conditions in hydrated mantle rocks of the overriding plate. Convergent margins in the initial phase of subduction must, therefore, be considered the most potent sites for prebiotic reactions on Earth. This means that origin of life processes are, perhaps, only possible on planets where some kind of plate tectonics occur. PMID:19849830

  19. Statistical-theoretical investigation of the thermal rate coefficient and branching ratio for the reaction O + HCN. -->. products

    SciTech Connect

    Miller, J.A.; Parrish, C.; Brown, N.J.

    1986-07-17

    Using the BAC-MP4 potential surface parameters of Melius and Binkley, we have predicted the thermal rate coefficients for the two reactions: O + HCN ..-->.. NCO + H (a) and O + HCN ..-->.. NH + CO (b). Several levels of approximation are used in the theoretical treatment: a, canonical theory; b, canonical theory with Wigner tunneling correction; c, microcanonical theory (energy conserving); d, microcanonical/J-conservative theory (conserves both energy and angular momentum); e, microcanonical/J-conservative theory with one-dimensional tunneling. At high temperature the available experimental results are predicted accurately by even the crudest theoretical treatment (canonical theory). At lower temperature the theoretical predictions using the basic BAC-MP4 parameters are too low. However, adjustments to the BAC-MP4 energy barriers within their stated error limits lead to satisfactory agreement with experiment over the entire temperature range where experimental results are available (500 to 2500 K). The most important results of the investigation concern the dependence of the predictions on the level of approximation. Each successive refinement in the theory produces larger values of k/sub b/. The details of the theoretical treatment and comparisons with experiment are described in detail.

  20. Noise-induced plasticity of KCNQ2/3 and HCN channels underlies vulnerability and resilience to tinnitus

    PubMed Central

    Li, Shuang; Kalappa, Bopanna I; Tzounopoulos, Thanos

    2015-01-01

    Vulnerability to noise-induced tinnitus is associated with increased spontaneous firing rate in dorsal cochlear nucleus principal neurons, fusiform cells. This hyperactivity is caused, at least in part, by decreased Kv7.2/3 (KCNQ2/3) potassium currents. However, the biophysical mechanisms underlying resilience to tinnitus, which is observed in noise-exposed mice that do not develop tinnitus (non-tinnitus mice), remain unknown. Our results show that noise exposure induces, on average, a reduction in KCNQ2/3 channel activity in fusiform cells in noise-exposed mice by 4 days after exposure. Tinnitus is developed in mice that do not compensate for this reduction within the next 3 days. Resilience to tinnitus is developed in mice that show a re-emergence of KCNQ2/3 channel activity and a reduction in HCN channel activity. Our results highlight KCNQ2/3 and HCN channels as potential targets for designing novel therapeutics that may promote resilience to tinnitus. DOI: http://dx.doi.org/10.7554/eLife.07242.001 PMID:26312501

  1. Baclofen ameliorates spatial working memory impairments induced by chronic cerebral hypoperfusion via up-regulation of HCN2 expression in the PFC in rats.

    PubMed

    Luo, Pan; Chen, Cheng; Lu, Yun; Fu, TianLi; Lu, Qing; Xu, Xulin; Li, Changjun; He, Zhi; Guo, Lianjun

    2016-07-15

    Chronic cerebral hypoperfusion (CCH) causes memory deficits and increases the risk of vascular dementia (VD) through several biologically plausible pathways. However, whether CCH causes prefrontal cortex (PFC)-dependent spatial working memory impairments and Baclofen, a GABAB receptor agonist, could ameliorate the impairments is still not clear especially the mechanisms underlying the process. In this study, rats were subjected to permanent bilateral occlusion of the common carotid arteries (two-vessel occlusion, 2VO) to induce CCH. Two weeks later, rats were treated with 25mg/kg Baclofen (intraperitioneal injection, i.p.) for 3 weeks. Spatial working memory was evaluated in a Morris water maze using a modified delayed matching-to-place (DMP) procedure. Western blotting and immunohistochemistry were used to quantify the protein levels and protein localization. Our results showed that 2VO caused striking spatial working memory impairments, accompanied with a decreased HCN2 expression in PFC, but the protein levels of protein gene product 9.5 (PGP9.5, a neuron specific protein), glial fibrillary acidic protein (GFAP), synaptophysin (SYP), brain-derived neurotrophic factor (BDNF), parvalbumin (PV) and HCN1 were not distinguishably changed as compared with sham-operated rats. Baclofen treatment significantly improved the spatial working memory impairments caused by 2VO, accompanied with a reversion of 2VO-induced down-regulation of HCN2. Furthermore, there was a co-localization of HCN2 subunits and parvalbumin-positive neurons in PFC. Therefore, HCN2 may target inhibitory interneurons that is implicated in working memory processes, which may be a possible mechanism of the up-regulation of HCN2 by Baclofen treatment that reliefs spatial working memory deficits in rats with CCH. PMID:27085590

  2. Efficient plasma-enhanced method for layered LiNi1/3Co1/3Mn1/3O2 cathodes with sulfur atom-scale modification for superior-performance Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Jiang, Qianqian; Chen, Ning; Liu, Dongdong; Wang, Shuangyin; Zhang, Han

    2016-05-01

    In order to improve the electrochemical performance of LiNi1/3Co1/3Mn1/3O2 as a lithium insertion positive electrode material, atom-scale modification was realized to obtain the layered oxysulfide LiNi1/3Co1/3Mn1/3O2-xSx using a novel plasma-enhanced doping strategy. The structure and electrochemical performance of LiNi1/3Co1/3Mn1/3O2-xSx are investigated systematically, which confirms that the S doping can make the structure stable and benefit the electrochemical performance. The phys-chemical characterizations indicate that oxygen atoms in the initial LiNi1/3Co1/3Mn1/3O2 have been partially replaced by S atoms. It should be pointed out that the atom-scale modification does not significantly alter the intrinsic structure of the cathode. Compared to the pristine material, the LiNi1/3Co1/3Mn1/3O2-xSx shows a superior performance with a higher capacity (200.4 mA h g-1) and a significantly improved cycling stability (maintaining 94.46% of its initial discharge capacity after 100 cycles). Moreover, it has an excellent rate performance especially at elevated performance, which is probably due to the faster Li+ transportation after S doping into the layered structure. All the results show that the atom-scale modification with sulfur atoms on LiNi1/3Co1/3Mn1/3O2, which significantly improved the electrochemical performance, offers a novel anionic doping strategy to realize the atom-scale modification of electrode materials to improve their electrochemical performance.In order to improve the electrochemical performance of LiNi1/3Co1/3Mn1/3O2 as a lithium insertion positive electrode material, atom-scale modification was realized to obtain the layered oxysulfide LiNi1/3Co1/3Mn1/3O2-xSx using a novel plasma-enhanced doping strategy. The structure and electrochemical performance of LiNi1/3Co1/3Mn1/3O2-xSx are investigated systematically, which confirms that the S doping can make the structure stable and benefit the electrochemical performance. The phys-chemical characterizations indicate that oxygen atoms in the initial LiNi1/3Co1/3Mn1/3O2 have been partially replaced by S atoms. It should be pointed out that the atom-scale modification does not significantly alter the intrinsic structure of the cathode. Compared to the pristine material, the LiNi1/3Co1/3Mn1/3O2-xSx shows a superior performance with a higher capacity (200.4 mA h g-1) and a significantly improved cycling stability (maintaining 94.46% of its initial discharge capacity after 100 cycles). Moreover, it has an excellent rate performance especially at elevated performance, which is probably due to the faster Li+ transportation after S doping into the layered structure. All the results show that the atom-scale modification with sulfur atoms on LiNi1/3Co1/3Mn1/3O2, which significantly improved the electrochemical performance, offers a novel anionic doping strategy to realize the atom-scale modification of electrode materials to improve their electrochemical performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02589g

  3. Efficient plasma-enhanced method for layered LiNi1/3Co1/3Mn1/3O2 cathodes with sulfur atom-scale modification for superior-performance Li-ion batteries.

    PubMed

    Jiang, Qianqian; Chen, Ning; Liu, Dongdong; Wang, Shuangyin; Zhang, Han

    2016-06-01

    In order to improve the electrochemical performance of LiNi1/3Co1/3Mn1/3O2 as a lithium insertion positive electrode material, atom-scale modification was realized to obtain the layered oxysulfide LiNi1/3Co1/3Mn1/3O2-xSx using a novel plasma-enhanced doping strategy. The structure and electrochemical performance of LiNi1/3Co1/3Mn1/3O2-xSx are investigated systematically, which confirms that the S doping can make the structure stable and benefit the electrochemical performance. The phys-chemical characterizations indicate that oxygen atoms in the initial LiNi1/3Co1/3Mn1/3O2 have been partially replaced by S atoms. It should be pointed out that the atom-scale modification does not significantly alter the intrinsic structure of the cathode. Compared to the pristine material, the LiNi1/3Co1/3Mn1/3O2-xSx shows a superior performance with a higher capacity (200.4 mA h g(-1)) and a significantly improved cycling stability (maintaining 94.46% of its initial discharge capacity after 100 cycles). Moreover, it has an excellent rate performance especially at elevated performance, which is probably due to the faster Li(+) transportation after S doping into the layered structure. All the results show that the atom-scale modification with sulfur atoms on LiNi1/3Co1/3Mn1/3O2, which significantly improved the electrochemical performance, offers a novel anionic doping strategy to realize the atom-scale modification of electrode materials to improve their electrochemical performance. PMID:27189799

  4. Seasonal variations of the amount of carbon allocated to respiration after in situ 13CO2 pulse labelling of trees (Invited)

    NASA Astrophysics Data System (ADS)

    Epron, D.; Dannoura, M.; Ngao, J.; Plain, C.; Berveller, D.; Chipeaux, C.; Gerant, D.; Bosc, A.; Maillard, P.; Loustau, D.; Damesin, C.; Cats Project (Anr-07-Blan-0109)

    2010-12-01

    Soil and trunk respiration are the major sources of carbon from forest ecosystems to the atmosphere and they account for a large fraction of total ecosystem respiration. The amount of photosynthate allocated to respiration affects the growth of the tree and the potential for carbon sequestration of forest ecosystems. This study, aiming at understanding patterns of carbon allocation to respiration among species and seasons, consisted in pure 13CO2 labelling of the entire crown of three different tree species (beech, oak and pine) at distinct phenological stages between Sept 2008 and Feb 2010. 13C was then tracked for several weeks in soil and trunk CO2 efflux at high temporal resolution using tuneable diode laser absorption spectrometry (Plain et al. 2009). Recovery of 13C in trunk and soil CO2 efflux was observed a few couple of hours after the beginning of the labelling in oak and beech. There is a rapid transfer of 13C belowground with a maximum occurring within 2 to 4 days after labelling. Label was recovered at the same time in the respiration and in the biomass of both fine roots and microbes. Maximum recovery occurred earlier in beech and oak, while it happened later in Pine. Indeed, the velocity of phloem transport, calculated as the difference of time lags in 13C recovery in trunk respiration at different height, was around 0.10-0.2m/h in pine and around 0.2-1.2 m/h in oak and beech, reflecting difference in phloem anatomy between angiosperm and gymnosperm. The cumulated amount of label recovered in soil CO2 efflux 20 days after labelling varied among the seasons in all species, from 1 to 16% in beech, 2 to 11% in oak and 1 to 11% in pine. For all species, allocation to soil respiration was greater in early summer compared to spring, late summer and autumn. A compartmental analysis is further conducted to characterise functional pools of labelled substrates and storage compounds that contribute to both trunk and soil respiration. [Plain C, Gérant D

  5. First Observations Of Titan With Herschel Spire

    NASA Astrophysics Data System (ADS)

    Courtin, Regis D.; Swinyard, B. M.; Fulton, T.; Lellouch, E.; Moreno, R.; Hartogh, P.; Jarchow, C.; Rengel, M.; HssO Team

    2010-10-01

    A Titan spectrum was recorded on June 22, 2010 with the SPIRE instrument of the Herschel Space Observatory as part of the guaranteed time key programme "Water and related chemistry in the Solar System" (KP-GT HssO). This initial spectrum, corresponding to an exposure time of 1322s, was designed as a test of the full 10h Titan observation performed on July 16, 2010. It covers the 14.6-51.8 cm-1 interval with a unapodized spectral resolution of 0.04 cm-1. Despite the limited integration time, numerous transitions are detected, notably those of CH4, CO, HCN, and of the isotopologues 13CO, C18O, H13CN, and HC15N. The analysis of this set of observations will provide new determinations of the abundances of these species, and hence new contraints on the isotopic ratios 12C/13C, 14N/15N and 16O/18O in Titan's atmosphere.

  6. Novel Li(Ni1/3Co1/3Mn1/3)O2 cathode morphologies for high power Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Oljaca, Miodrag; Blizanac, Berislav; Du Pasquier, Aurelien; Sun, Yipeng; Bontchev, Ranko; Suszko, Arek; Wall, Ryan; Koehlert, Kenneth

    2014-02-01

    In this paper, we report unique Li(Ni1/3Co1/3Mn1/3)O2 (NCM) materials produced using aerosol based liquid to solid conversion in different reactor configurations and using different atomization methods jointly termed Reactive Spray Technology (RST). A series of experiments was performed at different RST synthesis conditions suitable for large scale manufacturing to produce NCM powders with particle size ranging from 1 to ∼10 μm, varying degree of particle porosity and excellent compositional purity. The electrochemical testing in Li-ion cells indicates that NCM materials made via RST have high initial discharge capacity and good first cycle efficiency. NCM materials with small particle size and substantial intra-particle porosity show improved power rate performance at high discharge rates compared to larger particle size NCM. This was attributed to shorter diffusion length in the solid phase, increased electrochemically active surface area and high active phase accessibility due to the combined effect of smaller particle size and internal porosity. Specific capacity of small-particle NCM made by RST method was 167 mAh g-1 at 0.2 C and 137 mAh g-1 at 10 C, which compares favorably to 160 mAh g-1 at 0.2 C and 97 mAh g-1 at 10 C for NCM made by co-precipitation method having 10 μm average particle diameter.

  7. 13CO2/12CO2 isotope ratio analysis in human breath using a 2 μm diode laser

    NASA Astrophysics Data System (ADS)

    Sun, Mingguo; Cao, Zhensong; Liu, Kun; Wang, Guishi; Tan, Tu; Gao, Xiaoming; Chen, Weidong; Yinbo, Huang; Ruizhong, Rao

    2015-04-01

    The bacterium H. pylori is believed to cause peptic ulcer. H. pylori infection in the human stomach can be diagnosed through a CO2 isotope ratio measure in exhaled breath. A laser spectrometer based on a distributed-feedback semiconductor diode laser at 2 μm is developed to measure the changes of 13CO2/12CO2 isotope ratio in exhaled breath sample with the CO2 concentration of ~4%. It is characterized by a simplified optical layout, in which a single detector and associated electronics are used to probe CO2 spectrum. A new type multi-passes cell with 12 cm long base length , 29 m optical path length in total and 280 cm3 volume is used in this work. The temperature and pressure are well controlled at 301.15 K and 6.66 kPa with fluctuation amplitude of 25 mK and 6.7 Pa, respectively. The best 13δ precision of 0.06o was achieved by using wavelet denoising and Kalman filter. The application of denoising and Kalman filter not only improved the signal to noise ratio, but also shorten the system response time.

  8. IRAM 30 m large scale survey of {sup 12}CO(2-1) and {sup 13}CO(2-1) emission in the Orion molecular cloud

    SciTech Connect

    Berné, O.; Cernicharo, J.; Marcelino, N.

    2014-11-01

    Using the IRAM 30 m telescope, we have surveyed a 1 × 0.°8 part of the Orion molecular cloud in the {sup 12}CO and {sup 13}CO (2-1) lines with a maximal spatial resolution of ∼11'' and spectral resolution of ∼0.4 km s{sup –1}. The cloud appears filamentary, clumpy, and with a complex kinematical structure. We derive an estimated mass of the cloud of 7700 M {sub ☉} (half of which is found in regions with visual extinctions A{sub V} below ∼10) and a dynamical age for the nebula of the order of 0.2 Myr. The energy balance suggests that magnetic fields play an important role in supporting the cloud, at large and small scales. According to our analysis, the turbulent kinetic energy in the molecular gas due to outflows is comparable to turbulent kinetic energy resulting from the interaction of the cloud with the H II region. This latter feedback appears negative, i.e., the triggering of star formation by the H II region is inefficient in Orion. The reduced data as well as additional products such as the column density map are made available online (http://userpages.irap.omp.eu/∼oberne/Olivier{sub B}erne/Data).

  9. Quasi-ordered C60 molecular films grown on the pseudo-ten-fold (1 0 0) surface of the Al13Co4 quasicrystalline approximant.

    PubMed

    Fournée, V; Gaudry, É; Ledieu, J; de Weerd, M-C; Diehl, R D

    2016-09-01

    The growth of C60 films on the pseudo-ten-fold (1 0 0) surface of the orthorhombic Al13Co4 quasicrystalline approximant was studied experimentally by scanning tunneling microscopy, low-energy electron diffraction and photoemission spectroscopy. The (1 0 0) surface terminates at bulk-planes presenting local atomic configurations with five-fold symmetry-similar to quasicrystalline surfaces. While the films deposited at room temperature were found disordered, high-temperature growth (up to 693 K) led to quasi-ordered molecular films templated on the substrate rectangular unit mesh. The most probable adsorption sites and geometries were investigated by density functional theory (DFT) calculations. A large range of adsorption energies was determined, influenced by both symmetry and size matching at the molecule-substrate interface. The quasi-ordered structure of the film can be explained by C60 adsorption at the strongest adsorption sites which are too far apart compared to the distance minimizing the intermolecular interactions, resulting in some disorder in the film structure at a local scale. Valence band photoemission indicates a broadening of the molecular orbitals resulting from hybridization between the substrate and overlayer electronic states. Dosing the film at temperature above 693 K led to molecular damage and formation of carbide thin films possessing no azimuthal order with respect to the substrate. PMID:27365317

  10. Quasi-ordered C60 molecular films grown on the pseudo-ten-fold (1 0 0) surface of the Al13Co4 quasicrystalline approximant

    NASA Astrophysics Data System (ADS)

    Fournée, V.; Gaudry, É.; Ledieu, J.; de Weerd, M.-C.; Diehl, R. D.

    2016-09-01

    The growth of C60 films on the pseudo-ten-fold (1 0 0) surface of the orthorhombic Al13Co4 quasicrystalline approximant was studied experimentally by scanning tunneling microscopy, low-energy electron diffraction and photoemission spectroscopy. The (1 0 0) surface terminates at bulk-planes presenting local atomic configurations with five-fold symmetry—similar to quasicrystalline surfaces. While the films deposited at room temperature were found disordered, high-temperature growth (up to 693 K) led to quasi-ordered molecular films templated on the substrate rectangular unit mesh. The most probable adsorption sites and geometries were investigated by density functional theory (DFT) calculations. A large range of adsorption energies was determined, influenced by both symmetry and size matching at the molecule-substrate interface. The quasi-ordered structure of the film can be explained by C60 adsorption at the strongest adsorption sites which are too far apart compared to the distance minimizing the intermolecular interactions, resulting in some disorder in the film structure at a local scale. Valence band photoemission indicates a broadening of the molecular orbitals resulting from hybridization between the substrate and overlayer electronic states. Dosing the film at temperature above 693 K led to molecular damage and formation of carbide thin films possessing no azimuthal order with respect to the substrate.

  11. Combined FTIR-micrometeorological techniques for long term flux measurements of greenhouse gases and their applicability for 13CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Warneke, Thorsten; Caldow, Chris; Griffith, David

    2010-05-01

    Fourier Transform InfraRed (FTIR) spectrometry has been deployed for continuous long term flux measurements on a flat, homogeneous circular grass paddock in New South Wales, Australia. The rationale for using FTIR spectrometry is its capability to measure many species simultaneously. The flux measurement techniques combined with FTIR - spectrometry in this study were Disjunct Eddy Accumulation (DEA) and Flux-Gradient (FG). The fluxes of CO2 derived from the FTIR-DEA and FTIR-FG measurements agree well and have been validated by Eddy Covariance Licor measurements. Variations in the observed fluxes could be attributed to temperature increase and water availability over the 5 months measurement period. In addition to CO2, CH4, CO and N2O FTIR-spectrometry is also capable to measure 13CO2. The isotopic fluxes of CO2 allow to separate net ecosystem exchange of CO2 into its gross one-way component fluxes, ecosystem respiration and photosynthesis. It has been shown that it is possible to measure the isoflux of CO2.

  12. IRAM 30 m Large Scale Survey of 12CO(2-1) and 13CO(2-1) Emission in the Orion Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Berné, O.; Marcelino, N.; Cernicharo, J.

    2014-11-01

    Using the IRAM 30 m telescope, we have surveyed a 1 × 0.°8 part of the Orion molecular cloud in the 12CO and 13CO (2-1) lines with a maximal spatial resolution of ~11'' and spectral resolution of ~0.4 km s-1. The cloud appears filamentary, clumpy, and with a complex kinematical structure. We derive an estimated mass of the cloud of 7700 M ⊙ (half of which is found in regions with visual extinctions AV below ~10) and a dynamical age for the nebula of the order of 0.2 Myr. The energy balance suggests that magnetic fields play an important role in supporting the cloud, at large and small scales. According to our analysis, the turbulent kinetic energy in the molecular gas due to outflows is comparable to turbulent kinetic energy resulting from the interaction of the cloud with the H II region. This latter feedback appears negative, i.e., the triggering of star formation by the H II region is inefficient in Orion. The reduced data as well as additional products such as the column density map are made available online (http://userpages.irap.omp.eu/~oberne/Olivier_Berne/Data).

  13. Electrolyte additive to improve performance of MCMB/LiNi 1/3Co 1/3Mn 1/3O 2 Li-ion cell

    NASA Astrophysics Data System (ADS)

    Qin, Yan; Chen, Zonghai; Lu, Wenquan; Amine, Khalil

    The electrolyte additive, 3,9-divinyl-2,4,8,10-tetraoxaspiro[5,5] undecane (TOS), was investigated as a means to improve the life of mesocarbon microbead (MCMB)/Li 1.1[Ni 1/3Co 1/3Mn 1/3] 0.9O 2 (NCM) cells for high-power applications. With the addition of an appropriate amount of TOS (no more than 1 wt%) to MCMB/NCM cells, the capacity retention was significantly improved at 55 °C compared with cells containing pristine electrolyte. Aging tests at 55 °C indicated that the capacity retention of the negative electrode had benefited as a result of the formation of a stable passivation film at the surface of the carbon electrode due to TOS reduction. Electrochemical impedance spectroscopy showed that a TOS addition of more than 0.5 wt% increased the cell interfacial impedance. Differential scanning calorimetry showed that the thermal stability of lithiated MCMB was also improved with the TOS addition.

  14. Constellation of HCN channels and cAMP regulating proteins in dendritic spines of the primate prefrontal cortex: potential substrate for working memory deficits in schizophrenia.

    PubMed

    Paspalas, Constantinos D; Wang, Min; Arnsten, Amy F T

    2013-07-01

    Schizophrenia associates with impaired prefrontal cortical (PFC) function and alterations in cyclic AMP (cAMP) signaling pathways. These include genetic insults to disrupted-in-schizophrenia (DISC1) and phosphodiesterases (PDE4s) regulating cAMP hydrolysis, and increased dopamine D1 receptor (D1R) expression that elevates cAMP. We used immunoelectron microscopy to localize DISC1, PDE4A, PDE4B, and D1R in monkey PFC and to view spatial interactions with hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that gate network inputs when opened by cAMP. Physiological interactions between PDE4s and HCN channels were tested in recordings of PFC neurons in monkeys performing a spatial working memory task. The study reveals a constellation of cAMP-related proteins (DISC1, PDE4A, and D1R) and HCN channels next to excitatory synapses and the spine neck in thin spines of superficial PFC, where working memory microcircuits interconnect and spine loss is most evident in schizophrenia. In contrast, channels in dendrites were distant from synapses and cAMP-related proteins, and were associated with endosomal trafficking. The data suggest that a cAMP signalplex is selectively positioned in the spines to gate PFC pyramidal cell microcircuits. Single-unit recordings confirmed physiological interactions between cAMP and HCN channels, consistent with gating actions. These data may explain why PFC networks are especially vulnerable to genetic insults that dysregulate cAMP signaling. PMID:22693343

  15. Computational Studies Of Chemical Reactions: The Hnc-Hcn And Ch[subscript3]Nc-Ch[subscript3]Cn Isomerizations

    ERIC Educational Resources Information Center

    Halpern, Arthur M.

    2006-01-01

    The application of computational methods to the isomerization of hydrogen isocyanide to hydrogen cyanide, HNC-HCN is described. The logical extension to the exercise is presented to the isomerization of the methyl-substituted compounds, methylisocyanide and methylcyanide, Ch[subscript 3]NC-CH[subscript3]CN.

  16. The initial vibrational state distribution of HCN {ital {tilde X}} {sup 1}{Sigma}{sup +}({ital v}{sub 1},0,{ital v}{sub 3}) from the reaction CN({sup 2}{Sigma}{sup +})+C{sub 2}H{sub 6}{r_arrow}HCN+C{sub 2}H{sub 5}

    SciTech Connect

    Bethardy, G.A.; Northrup, F.J.; Macdonald, R.G.

    1995-05-22

    The reaction of the cyano radical (CN) with ethane was studied using time-resolved infrared absorption spectroscopy to monitor individual rovibrational states of the HCN product. A method is described that can be used to determine the initial vibrational state distribution at pressures of several Torr. This technique was applied to the title reaction to determine that the vibrational states of HCN({ital v}{sub 1},0,{ital v}{sub 3}), where {ital v}{sub 1}, {ital v}{sub 3}=0, 1, and 2, were {ital not} directly populated in the title reaction to any significant extent. The initial vibrational energy content of the CN radical was also varied but did not influence the initial population in the HCN vibrational levels probed in this experiment. The time dependence of HCN({ital v}{sub 1},0,{ital v}{sub 3}) was followed and interpreted in terms of bimolecular rate constants for vibrational relaxation with ethane. The title reaction is mode specific in its energy disposal in that at least every HCN product appears to have at least one quantum of bending excitation, likely in combination with stretching vibrations.

  17. Submillimeter Monitoring of the HCN Molecule in Fragment C of the Split Comet 73P/Schwassmann-Wachmann 3

    NASA Astrophysics Data System (ADS)

    Drahus, Michal; Kueppers, M.; Jarchow, C.; Paganini, L.; Hartogh, P.; Villanueva, G. L.

    2007-10-01

    Comet 73P/Schwassmann-Wachmann 3 is a member of the Jupiter family which broke up into several fragments in 1995. After the unfavourable return in 2000/2001, the comet passed very close to the Earth in 2006, with the perigee distance below 0.1 AU. Simultaneously, it was well situated on the sky, which resulted in several observing campaigns. We observed this comet using the SMT facility at the Mt. Graham International Observatory in Arizona. In particular, on 5 nights between 10 and 22 May 2006 the HCN molecule in fragment C was spectroscopically monitored, through the J(3-2) and J(4-3) transitions. Using a simplified model, we found the expansion velocity of the HCN coma to be equal to 0.8 ± 0.1 km/s, what is a typical value for a comet at heliocentric distance r = 1 AU. We also reconstructed the production rates Q of this molecule, finding Q(r=1AU) = 2.7 ± 0.1 × 1025 molec/s. Our result is consistent with most of the other estimates, including the CN production rate. Furthermore, taking advantage of the fairly small beam sizes during our campaign (ranging from 600 km to 1200 km in radius), we detected short-term variability of the production rate, presumably stimulated by the nucleus rotation. Although our analysis did not yield a unique rotation period, we found a limited number of possible solutions. We will discuss them in detail along with a comparison with other period claims, and propose a possible scenario that links most of the periodicities reported so far for this comet. The SMT is operated by the Arizona Radio Observatory (ARO), Steward Observatory, University of Arizona.

  18. Preparation and characterization of layered LiMn 1/3Ni 1/3Co 1/3O 2 as a cathode material by an oxalate co-precipitation method

    NASA Astrophysics Data System (ADS)

    Cho, Tae-Hyung; Shiosaki, Yuki; Noguchi, Hideyuki

    The layered LiMn 1/3Ni 1/3Co 1/3O 2 cathode materials were synthesized by an oxalate co-precipitation method using different starting materials of LiOH, LiNO 3, [Mn 1/3Ni 1/3Co 1/3]C 2O 4·2H 2O and [Mn 1/3Ni 1/3Co 1/3] 3O 4. The morphology, structural and electrochemical behavior were characterized by means of SEM, X-ray diffraction analysis and electrochemical charge-discharge test. The cathode material synthesized by using LiNO 3 and [Mn 1/3Ni 1/3Co 1/3]C 2O 4·2H 2O showed higher structural integrity and higher reversible capacity of 178.6 mAh g -1 in the voltage range 3.0-4.5 V versus Li with constant current density of 40 mA g -1 as well as lower irreversible capacity loss of 12.9% at initial cycle. The rate capability of the cathode was strongly influenced by particle size and specific surface area.

  19. Microwave Plasma Chemical Vapor Deposition of Carbon Coatings on LiNi1/3Co1/3Mn1/3O2 for Li-Ion Battery Composite Cathodes

    SciTech Connect

    Doeff, M.M.; Kostecki, R.; Marcinek, M.; Wilcoc, J.D.

    2008-12-10

    In this paper, we report results of a novel synthesis method of thin film conductive carbon coatings on LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} cathode active material powders for lithium-ion batteries. Thin layers of graphitic carbon were produced from a solid organic precursor, anthracene, by a one-step microwave plasma chemical vapor deposition (MPCVD) method. The structure and morphology of the carbon coatings were examined using SEM, TEM, and Raman spectroscopy. The composite LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrodes were electrochemically tested in lithium half coin cells. The composite cathodes made of the carbon-coated LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} powder showed superior electrochemical performance and increased capacity compared to standard composite LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrodes.

  20. Dense gas tracing the collisional past of Andromeda. An atypical inner region?

    NASA Astrophysics Data System (ADS)

    Melchior, Anne-Laure; Combes, Françoise

    2016-01-01

    The central kiloparsec region of the Andromeda galaxy is relatively gas poor, while the interstellar medium appears to be concentrated in a ring-like structure at about 10 kpc radius. The central gas depletion has been attributed to a possible head-on collision 200 Myr ago, supported by the existence of an offset inner ring of warm dust. We present new IRAM 30 m radio telescope observations of the molecular gas in the central region, and the detection of CO and its isotopes 13CO(2-1) and C18O(2-1), together with the dense gas tracers, HCN(1-0) and HCO+(1-0). A systematic study of the observed peak temperatures with non-local thermal equilibrium simulations shows that the detected lines trace dense regions with nH2 in the range 2.5 × 104-5.6 × 105 cm-3, while the gas is very clumpy with a beam filling factor of 0.5-2 × 10-2. This is compatible with the dust mass derived from the far-infrared emission, assuming a dust-to-gas mass ratio of 0.01 with a typical clump size of 2 pc. We also show that the gas is optically thin in all lines except for 12CO(1-0) and 12CO(2-1), CO lines are close to their thermal equilibrium condition at 17-20 K, the molecular hydrogen density is larger than critical, and HCN and HCO+ lines have a subthermal excitation temperature of 9 K with a density smaller than critical. The average 12CO/13CO line ratio is high (~21), and close to the 12CO/C18O ratio (~30) that was measured in the north-western region and estimated in the south-east stacking. The fact that the optically thin 13CO and C18O lines have comparable intensities means that the secondary element 13C is depleted with respect to the primary 12C, as is expected just after a recent star formation. This suggests that there has been a recent starburst in the central region, supporting the head-on collision scenario. Based on observations carried out with the IRAM 30 m radio telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  1. Adsorption of O2 and C2Hn (n = 2, 4, 6) on the Al9Co2(0 0 1) and o-Al13Co4(1 0 0) complex metallic alloy surfaces

    NASA Astrophysics Data System (ADS)

    Wardé, M.; Herinx, M.; Ledieu, J.; Serkovic Loli, L. N.; Fournée, V.; Gille, P.; Le Moal, S.; Barthés-Labrousse, M.-G.

    2015-12-01

    Oxidation of the Al9Co2(0 0 1) and Al13Co4(1 0 0) surfaces has been performed in a wide range of temperatures at 2 × 10-8 or 1 × 10-7 mbar oxygen pressure. Only Alsbnd O bonding is observed. The oxidation kinetics are controlled by the quantity of oxygen sticking on the surface. Oxidation results from a competition between several effects: formation of an oxide film, dissolution of the film, oxygen desorption and oxygen dissolution into the bulk. For temperatures lower than 710 K for the Al9Co2(0 0 1) surface and 925 K for the Al13Co4(1 0 0) surface, a ∼5 Å thick oxide film is formed which does not show any long-range order and desorbs upon annealing. When oxidation is performed at higher temperatures, oxygen diffusion into the bulk is observed. A poorly ordered oxide film having a sixton structure is formed on the Al9Co2(0 0 1) surface when oxidation is performed at 775 K, which is dissolved when annealing at higher temperatures. On the Al13Co4(1 0 0) surface, only a weak streaky polar circle is observed following annealing at 925 K the film formed at room temperature, which corresponds to an hexagonal network of O atoms into small ultrathin oxide layers domains. The oxidation behaviour of the Al9Co2(0 0 1) and Al13Co4(1 0 0) surfaces has been ascribed to the strong covalent character of bonds present in these Alsbnd Co phases, which prevents aluminium diffusion. C2Hn molecules (n = 2, 4, 6) do not adsorb on the Al13Co4(1 0 0) surface in the experimental conditions used in this study, thus suggesting that this surface might not be the active one in the semi-hydrogenation of acetylene.

  2. Sensitive CO and 13CO survey of water fountain stars. Detections towards IRAS 18460-0151 and IRAS 18596+0315

    NASA Astrophysics Data System (ADS)

    Rizzo, J. R.; Gómez, J. F.; Miranda, L. F.; Osorio, M.; Suárez, O.; Durán-Rojas, M. C.

    2013-12-01

    Context. Water fountain stars represent a stage between the asymptotic giant branch (AGB) and planetary nebulae phases, when the mass loss changes from spherical to bipolar. These types of evolved objects are characterized by high-velocity jets in the 22 GHz water maser emission. Aims: The objective of this work is to detect and study in detail the circumstellar gas in which the bipolar outflows are emerging. The detection and study of thermal lines may help in understanding the nature and physics of the envelopes in which the jets are developing. Methods: We surveyed the CO and 13CO line emission towards a sample of ten water fountain stars through observing the J = 1 → 0 and 2 → 1 lines of CO and 13CO, using the 30 m IRAM radio-telescope at Pico Veleta. All the water fountains visible from the observatory were surveyed. Results: Most of the line emission arises from foreground or background Galactic clouds, and we had to thoroughly analyse the spectra to unveil the velocity components related to the stars. In two sources, IRAS 18460-0151 and IRAS 18596+0315, we identified wide velocity components with a width of 35 - 40 km s-1 that are centred at the stellar velocities. These wide components can be associated with the former AGB envelope of the progenitor star. A third case, IRAS 18286-0959, is reported as tentative; in this case a pair of narrow velocity components, symmetrically located with respect to the stellar velocity, have been discovered. We also modelled the line emission using an LVG code and derived some global physical parameters, which allowed us to discuss the possible origin of this gas in relation to the known bipolar outflows. For IRAS 18460-0151 and IRAS 18596+0315, we derived molecular masses close to 0.2 M⊙, mean densities of 104 cm-3, and mass-loss rates of 10-4 M⊙ yr-1. The kinetic temperatures are rather low, between 10 and 50 K in both cases, which suggests that the CO emission is arising from the outer and cooler regions of the

  3. Measuring and modelling the intra-day variability of the 13CO2 & 12CO2 vertical soil profile production in a Scots pine forest

    NASA Astrophysics Data System (ADS)

    Longdoz, Bernard; Goffin, Stéphanie; Parent, Florian; Plain, Caroline; Epron, Daniel; Wylock, Christophe; Haut, Benoit; Aubinet, Marc; Maier, Martin

    2015-04-01

    Vertical profile of CO2 production (Ps) and transport, as well as their isotopic discrimination (13CO2/12CO2) should be considered to improve the soil CO2 efflux (Fs) mechanistic understanding and especially its short-term temporal variations. In this context, we propose a new methodology able to measure continuously and simultaneously Fs, the vertical soil CO2 concentration ([CO2]) profile and their respective isotopic signature (δFs and δCO2) [1]. The Ps of the different soil layers and their isotopic signature (δPs) can then be determined from these measurements by an approach considering diffusion as the only gas transport. A field campaign was conducted with this device at the Scots Pine Hartheim forest (Germany). The results [2] show (i) a Ps dependence on local temperature specific for each layer, (ii) an enrichment of δPs with soil drought, (iii) Fs and [CO2] large intra-day fluctuations non explained by the soil temperature and moisture. These fluctuations can be generated by other processes creating Ps and/or transport variability. To investigate about the nature of these processes, some sensitivity analyses have been performed with a soil CO2 model simulating both production and transport. The impacts of the introduction of advection, dispersion and phloem pressure concentration wave (through dependence of Ps on vapour pressure deficit) on intra-day Fs and [CO2] variations have been quantified. We conclude that these variations are significantly better represented when the phloem pressure wave expression is included in the simulations. The study of the processes related to CO2 production seems to be a better option than an investigation about transport to explain the intra-day Fs variability.

  4. Spatially Resolved Electronic Alterations As Seen by in Situ 195Pt and 13CO NMR in Ru@Pt and Au@Pt Core-Shell Nanoparticles

    SciTech Connect

    Atienza, Dianne O.; Allison, Thomas C.; Tong, Yu ye J.

    2012-12-20

    Pt-based core-shell (M@Pt where M stands for core element) nanoparticles (NPs) have recently been under increasing scrutiny in the fields of fuel cell and lithium air battery electrocatalysis due to their promising prospects in optimizing catalytic activity, reducing Pt loading and consequently lowering its cost. To achieve the latter, delineating spatially resolved local (surface) elemental distribution and associated variations in electronic properties under working condition (i.e., in situ) is arguably a prerequisite of fundamental importance in investigating electrocatalysis but unfortunately is still sorely missing. In this regard, in situ 195Pt electrochemical NMR (EC-NMR) of Pt-based NPs is unique in terms of accessing such information, particularly the spatially resolved partition between the sand d-like Fermi level local density of states (Ef-LDOS) modified by the core elements. In this paper, we report a comparative in situ 195Pt EC-NMR investigation of Ru@Pt vs Au@Pt NPs which was complemented by in situ 13C EC-NMR of the 13CO adsorbed on the respective NPs generated via dissociation of methanol and by ab initio DFT calculations. The obtained results showed opposing electronic effect between Ru vs Au cores: the former reduced substantially the s-like but not the d-like Ef-LDOS of the Pt shell while the latter did the opposite. According to recent quantum calculations, a reduction in d-like partition would weaken the Pt-O bond while a reduction in s-like partition would weaken the Pt-H bond, which is largely in agreement with experimental observations.

  5. The truth about the 1st cycle Coulombic efficiency of LiNi1/3Co1/3Mn1/3O2 (NCM) cathodes.

    PubMed

    Kasnatscheew, J; Evertz, M; Streipert, B; Wagner, R; Klöpsch, R; Vortmann, B; Hahn, H; Nowak, S; Amereller, M; Gentschev, A-C; Lamp, P; Winter, M

    2016-02-01

    The 1st cycle Coulombic efficiency (CE) of LiNi1/3Co1/3Mn1/3O2 (NCM) at 4.6 V vs. Li/Li(+) has been extensively investigated in NCM/Li half cells. It could be proven that the major part of the observed overall specific capacity loss (in total 36.3 mA h g(-1)) is reversible and induced by kinetic limitations, namely an impeded lithiation reaction during discharge. A measure facilitating the lithiation reaction, i.e. a constant potential (CP) step at the discharge cut-off potential, results in an increase in specific discharge capacity of 22.1 mA h g(-1). This capacity increase during the CP step could be proven as a relithiation process by Li(+) content determination in NCM via an ICP-OES measurement. In addition, a specific capacity loss of approx. 4.2 mA h g(-1) could be determined as an intrinsic reaction to the NCM cathode material at room temperature (RT). In total, less than 10.0 mA h g(-1) (=28% of the overall capacity loss) can be attributed to irreversible reactions, mainly to irreversible structural changes of NCM. Thus, the impact of parasitic reactions, such as oxidative electrolyte decomposition, on the irreversible capacity is negligible and could also be proven by on-line MS. As a consequence, the determination of the amount of extracted Li(+) ("Li(+) extraction ratio") so far has been incorrect and must be calculated by the charge capacity (=delithiation amount) divided by the theoretical capacity. In a NCM/graphite full cell the relithiation amount during the constant voltage (CV) step is smaller than in the half cell, due to irreversible Li(+) loss at graphite. PMID:26771035

  6. Rapid, Long-term Monitoring of CO2 Concentration and δ13CO2 at CCUS Sites Allows Discrimination of Leakage Patterns from Natural Background Values

    NASA Astrophysics Data System (ADS)

    Galfond, B.; Riemer, D. D.; Swart, P. K.

    2014-12-01

    In order for Carbon Capture Utilization and Storage (CCUS) to gain wide acceptance as a method for mitigating atmospheric CO2 concentrations, schemes must be devised to ensure that potential leakage is detected. New regulations from the US Environmental Protection Agency require monitoring and accounting for Class VI injection wells, which will remain a barrier to wide scale CCUS deployment until effective and efficient monitoring techniques have been developed and proven. Monitoring near-surface CO2 at injection sites to ensure safety and operational success requires high temporal resolution CO2 concentration and carbon isotopic (δ13C) measurements. The only technologies currently capable of this rapid measurement of δ13C are optical techniques such as Cavity Ringdown Spectroscopy (CRDS). We have developed a comprehensive remote monitoring approach using CRDS and a custom manifold system to obtain accurate rapid measurements from a large sample area over an extended study period. Our modified Picarro G1101-i CRDS allows for automated rapid and continuous field measurement of δ13CO2 and concentrations of relevant gas species. At our field site, where preparations have been underway for Enhanced Oil Recovery (EOR) operations, we have been able to measure biogenic effects on a diurnal scale, as well as variation due to precipitation and seasonality. Taking these background trends into account, our statistical treatment of real data has been used to improve signal-to-noise ratios by an order of magnitude over published models. Our system has proven field readiness for the monitoring of sites with even modest CO2 fluxes.

  7. HCN and CN in comet 2P/Encke, a three-dimensional view on comet Encke's outgassing

    NASA Astrophysics Data System (ADS)

    Jockers, K.; Szutowicz, S.

    2008-09-01

    Background Simultaneous radio and optical observations of chemically related species in comets promise to supplement each other favorably. High resolution spectra of a submillimeter line provide the distribution of radial velocity. Narrow-band images in the optical region offer the spatial distribution of a species projected into the sky plane perpendicular to the line of sight. Therefore optical and radio observations can in principle be combined into a three-dimensional picture of a comet. A suitable pair of species accessible in the microwave and optical wavelength range is provided by HCN (one of the strongest radio emissions of comets) and CN (strong optical emission). HCN is the most probable parent of CN, but other parents of CN are possible. In this study we use HCN and CN observations of comet it 2P/Encke to address the parental relation of HCN with respect to CN and to investigate the gas outflow from a cometary surface and its dependence on location on the surface (the question of so-called "active vents" or "active areas") and on solar zenith angle. Some known facts about Comet 2P/Encke Comet 2P/Encke is a short period comet. It has the smallest known perihelion distance q = 0.33 AU and a period of 3.28 years. Because of its closeness to the Sun Comet Encke probably is the most evolved comet known. In the optical wavelength range comet Encke does not display a dust tail. Instead a so-called "fan" is observed, a broad feature visible at the solar side of the comet but not directly pointing to the Sun. In the far infrared spectral region Comet Encke displays a huge coma [1] of large dust grains but because of their large size these grains do not contibute significantly to the optical image [2]. In a study based on a large number of historical observations Sekanina [3] has investigated comet Encke's fan-shaped coma. According to this author comet Encke's north rotation pole is located at right ascension 205° and declination 2° (equinox 1950.0). Two vents

  8. Enhanced electrochemical performance of Li-rich cathode Li[Li0.2Mn0.54Ni0.13Co0.13]O2 by surface modification with lithium ion conductor Li3PO4

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyuan; Luo, Shaohua; Ren, Jie; Wang, Dan; Qi, Xiwei

    2016-05-01

    Li-rich layered cathode Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is prepared via a co-precipitation followed with high-temperature calcination, and then successfully modified with nano-Li3PO4 by ball milling and annealing. The TEM and EDS reveal that Li3PO4 is homogeneously coated on the particle surface of Li[Li0.2Mn0.54Ni0.13Co0.13]O2. And the electrochemical performance of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is significantly improved by coating with lithium ion conductor Li3PO4. The Li3PO4-coated sample delivers a high initial discharge capacity of 284.7 mAhg-1 at 0.05 C, and retains 192.6 mAhg-1 after 100 cycles at 0.5 C, which is higher than that of the pristine sample (244 mAhg-1 at 0.05 C and 168.2 mAhg-1 after 100 cycles at 0.5 C). The electrochemical impedance spectroscopy (EIS) demonstrates that the resistance for Li/Li3PO4-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cell was reduced compared to Li/Li[Li0.2Mn0.54Ni0.13Co0.13]O2, which indicates the Li3PO4 coating layer with high ionic conductivity (6.6 × 10-8 S cm-1) facilitates the diffusion of lithium ions through the interface between electrode and electrolyte and accelerates the charge transfer process. What is more, the Li3PO4 coating layer can also act as a protection layer to protect the cathode material from encroachment of electrolyte. The two aspects account for the enhanced electrochemical performance of Li3PO4-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2.

  9. In situ 13CO2 pulse labelling of field-grown eucalypt trees revealed the effects of potassium nutrition and throughfall exclusion on phloem transport of photosynthetic carbon.

    PubMed

    Epron, Daniel; Cabral, Osvaldo Machado Rodrigues; Laclau, Jean-Paul; Dannoura, Masako; Packer, Ana Paula; Plain, Caroline; Battie-Laclau, Patricia; Moreira, Marcelo Zacharias; Trivelin, Paulo Cesar Ocheuze; Bouillet, Jean-Pierre; Gérant, Dominique; Nouvellon, Yann

    2016-01-01

    Potassium (K) is an important limiting factor of tree growth, but little is known of the effects of K supply on the long-distance transport of photosynthetic carbon (C) in the phloem and of the interaction between K fertilization and drought. We pulse-labelled 2-year-old Eucalyptus grandis L. trees grown in a field trial combining K fertilization (+K and -K) and throughfall exclusion (+W and -W), and we estimated the velocity of C transfer by comparing time lags between the uptake of (13)CO2 and its recovery in trunk CO2 efflux recorded at different heights. We also analysed the dynamics of the labelled photosynthates recovered in the foliage and in the phloem sap (inner bark extract). The mean residence time of labelled C in the foliage was short (21-31 h). The time series of (13)C in excess in the foliage was affected by the level of fertilization, whereas the effect of throughfall exclusion was not significant. The velocity of C transfer in the trunk (0.20-0.82 m h(-1)) was twice as high in +K trees than in -K trees, with no significant effect of throughfall exclusion except for one +K -W tree labelled in the middle of the drought season that was exposed to a more pronounced water stress (midday leaf water potential of -2.2 MPa). Our results suggest that besides reductions in photosynthetic C supply and in C demand by sink organs, the lower velocity under K deficiency is due to a lower cross-sectional area of the sieve tubes, whereas an increase in phloem sap viscosity is more likely limiting phloem transport under drought. In all treatments, 10 times less (13)C was recovered in inner bark extracts at the bottom of the trunk when compared with the base of the crown, suggesting that a large part of the labelled assimilates has been exported out of the phloem and replaced by unlabelled C. This supports the 'leakage-retrieval mechanism' that may play a role in maintaining the pressure gradient between source and sink organs required to sustain high

  10. Hydrogen constituents of the mesosphere inferred from positive ions - H2O, CH4, H2CO, H2O2, and HCN

    NASA Technical Reports Server (NTRS)

    Kopp, E.

    1990-01-01

    The concentrations in the mesosphere of H2O, CH4, H2CO, H2O2, and HCN were inferred from data on positive ion compositions, obtained from one mid-latitude and four high-latitude rocket flights. The inferred concentrations were found to agree only partially with the ground-based microwave measurements and/or model prediction by Garcia and Solomon (1985). The CH4 concentration was found to vary between 70 and 4 ppb in daytime and 900 and 100 ppbv at night, respectively. Unexpectedly high H2CO concentrations were obtained, with H2CO/H2O ratios between 0.0006 and 0.1, and a mean HCN volume mixing ratio of 6 x 10 to the -10th was inferred.

  11. The polythiophene molecular segment as a sensor model for H2O, HCN, NH3, SO3, and H2S: a density functional theory study.

    PubMed

    Shokuhi Rad, Ali; Esfahanian, Mehri; Ganjian, Etesam; Tayebi, Habib-Allah; Novir, Samaneh Bagheri

    2016-06-01

    Studying the interaction of some atmospheric gases (H2O, HCN, NH3, SO3 and H2S) with 3PT oligomers is important in the development of polymeric sensors for gas detection. In the present study, we studied the relaxed geometries, interaction energies, charge analysis, HOMO-LUMO orbital analysis, and UV-vis spectra of all interacted systems using first-principles density functional theory (DFT). All these analyses indicated the potential of polythiophene as an inexpensive polymeric sensor for the analytes mentioned. Interaction energy values of -19.90, -19.66, -14.01, -8.70, and -4.76 kJ mol(-1) were achieved for adsorption of SO3, H2O, NH3, HCN, and H2S on 3PT, respectively. Consequently, clarification of their physical parameters became the major focus of this study. PMID:27178416

  12. Stability and breakdown of Ca13CO3 melt associated with formation of 13C-diamond in static high pressure experiments up to 43 GPa and 3900 K

    NASA Astrophysics Data System (ADS)

    Spivak, A. V.; Litvin, Yu. A.; Ovsyannikov, S. V.; Dubrovinskaia, N. A.; Dubrovinsky, L. S.

    2012-07-01

    Melting of calcium carbonate Ca13CO3, stability of the melt and its decomposition were studied in static high pressure experiments at pressures of 11-43 GPa and temperatures of 1600-3900 K using diamond anvil cell technique with laser heating. We observed formation of 13C-graphite (below 16 GPa) and 13C-diamond (between 16 and 43 GPa) on decomposition of the Ca13CO3 melt at temperatures above 3400 K. At temperatures below 3400 K congruent melting of calcium carbonate was confirmed. The experimental results were applied to construction of the phase diagram of CaCO3 up to 43 GPa and 3900 K focusing at the melting curve of calcium carbonate and the decomposition phase boundary of CaCO3 melt.

  13. A Multispectrum Analysis of the v(1) band of (HCN)-C-12-N-14: Part I. Intensities, Self-broadening and self-shift Coefficients

    SciTech Connect

    Malathy Devi, V.; Benner, D. Chris; Smith, M H.; Rinsland, Curtis P.; Sharpe, Steven W.; Sams, Robert L.

    2003-12-01

    The infrared spectrum of HCN in the region between 3150 and 3450 cm-1 has been recorded at 0.005 and 0.008 cm-1 resolution using two different Fourier transform spectrometers, the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory (on Kitt Peak)and the Bruker-120HR Fourier transform spectrometer situated at the Pacific Northwest National Laboratory at Richland, Washington.

  14. Rate Coefficients for Reactions of Ethynyl Radical (C2H) With HCN and CH3CN: Implications for the Formation of Comples Nitriles on Titan

    NASA Technical Reports Server (NTRS)

    Hoobler, Ray J.; Leone, Stephen R.

    1997-01-01

    Rate coefficients for the reactions of C2H + HCN yields products and C2H + CH3CN yields products have been measured over the temperature range 262-360 K. These experiments represent an ongoing effort to accurately measure reaction rate coefficients of the ethynyl radical, C2H, relevant to planetary atmospheres such as those of Jupiter and Saturn and its satellite Titan. Laser photolysis of C2H2 is used to produce C2H, and transient infrared laser absorption is employed to measure the decay of C2H to obtain the subsequent reaction rates in a transverse flow cell. Rate constants for the reaction C2H + HCN yields products are found to increase significantly with increasing temperature and are measured to be (3.9-6.2) x 10(exp 13) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 297-360 K. The rate constants for the reaction C2H + CH3CN yields products are also found to increase substantially with increasing temperature and are measured to be (1.0-2.1) x 10(exp -12) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 262-360 K. For the reaction C2H + HCN yields products, ab initio calculations of transition state structures are used to infer that the major products form via an addition/elimination pathway. The measured rate constants for the reaction of C2H + HCN yields products are significantly smaller than values currently employed in photochemical models of Titan, which will affect the HC3N distribution.

  15. THE SOURCES OF HCN AND CH{sub 3}OH AND THE ROTATIONAL TEMPERATURE IN COMET 103P/HARTLEY 2 FROM TIME-RESOLVED MILLIMETER SPECTROSCOPY

    SciTech Connect

    Drahus, Michal; Jewitt, David; Guilbert-Lepoutre, Aurelie; Waniak, Waclaw; Sievers, Albrecht

    2012-09-01

    One of the least understood properties of comets is the compositional structure of their nuclei, which can either be homogeneous or heterogeneous. The nucleus structure can be conveniently studied at millimeter wavelengths, using velocity-resolved spectral time series of the emission lines, obtained simultaneously for multiple molecules as the body rotates. Using this technique, we investigated the sources of CH{sub 3}OH and HCN in comet 103P/Hartley 2, the target of NASA's EPOXI mission, which had an exceptionally favorable apparition in late 2010. Our monitoring with the IRAM 30 m telescope shows short-term variability of the spectral lines caused by nucleus rotation. The varying production rates generate changes in brightness by a factor of four for HCN and by a factor of two for CH{sub 3}OH, and they are remarkably well correlated in time. With the addition of the velocity information from the line profiles, we identify the main sources of outgassing: two jets, oppositely directed in a radial sense, and icy grains, injected into the coma primarily through one of the jets. The mixing ratio of CH{sub 3}OH and HCN is dramatically different in the two jets, which evidently shows large-scale chemical heterogeneity of the nucleus. We propose a network of identities linking the two jets with morphological features reported elsewhere and postulate that the chemical heterogeneity may result from thermal evolution. The model-dependent average production rates are 3.5 Multiplication-Sign 10{sup 26} molecules s{sup -1} for CH{sub 3}OH and 1.25 Multiplication-Sign 10{sup 25} molecules s{sup -1} for HCN, and their ratio of 28 is rather high but not abnormal. The rotational temperature from CH{sub 3}OH varied strongly, presumably due to nucleus rotation, with the average value being 47 K.

  16. Formation of hydroxyacetonitrile (HOCH2CN) and polyoxymethylene (POM)-derivatives in comets from formaldehyde (CH2O) and hydrogen cyanide (HCN) activated by water.

    PubMed

    Danger, Grégoire; Rimola, Albert; Abou Mrad, Ninette; Duvernay, Fabrice; Roussin, Gaël; Theule, Patrice; Chiavassa, Thierry

    2014-02-28

    Studying chemical reactivity is an important way to improve our understanding of the origin of organic matter in astrophysical environments such as molecular clouds, protoplanetary disks, and possibly, as a final destination, in our solar system bodies such as in comets. Laboratory simulations on the reactivity of ice analogs can provide important insights into this complex reactivity. Here, the role of water as a catalytic agent is investigated under the conditions of simulated interstellar and cometary grains in the formation of complex organic molecules: the hydroxyacetonitrile (HOCH2CN) and formaldehyde polymers (polyoxymethylene POM). Using infrared spectroscopy and mass spectrometry, we show that HCN reacts with CH2O only in the presence of H2O, whereas in the absence of H2O, HCN is not sufficiently reactive to promote this reaction. Furthermore, depending on the dilution of CH2O and HCN in the water matrix, 1-cyanopolyoxymethylene polymers can also be formed (H-(O-CH2)n-CN, POM-CN), as confirmed by mass spectrometry using the HC(15)N isotopologue. Moreover, quantum chemical calculations allowed us to suggest mechanistic proposals for these reactions, the first step being the activation of HCN by water forming H3O(+) and CN(-), which subsequently condense on a neighbouring CH2O promoting the formation of (-)OCH2CN. Once (-)OCH2CN is formed, it can either recover a proton by reacting with H3O(+) or condense on CH2O molecules leading to POM-CN structures. Implications of this work for the forthcoming Rosetta mission are also addressed. PMID:24202268

  17. Structural changes and thermal stability of charged LiNi 1/3Co 1/3Mn 1/3O 2 cathode material for Li-ion batteries studied by time-resolved XRD

    NASA Astrophysics Data System (ADS)

    Nam, Kyung-Wan; Yoon, Won-Sub; Yang, Xiao-Qing

    Structural changes and their relationship with thermal stability of charged Li 0.33Ni 1/3Co 1/3Mn 1/3O 2 cathode samples have been studied using time-resolved X-ray diffraction (TR-XRD) in a wide temperature from 25 to 600 °C with and without the presence of electrolyte in comparison with Li 0.27Ni 0.8Co 0.15Al 0.05O 2 cathodes. Unique phase transition behavior during heating is found for the Li 0.33Ni 1/3Co 1/3Mn 1/3O 2 cathode samples: when no electrolyte is present, the initial layered structure changes first to a LiM 2O 4-type spinel, and then to a M 3O 4-type spinel and remains in this structure up to 600 °C. For the Li 0.33Ni 1/3Co 1/3Mn 1/3O 2 cathode sample with electrolyte, additional phase transition from the M 3O 4-type spinel to the MO-type rock salt phase takes place from about 400 to 441 °C together with the formation of metallic phase at about 460 °C. The major difference between this type of phase transitions and that for Li 0.27Ni 0.8Co 0.15Al 0.05O 2 in the presence of electrolyte is the delayed phase transition from the spinel-type to the rock salt-type phase by stretching the temperature range of spinel phases from about 20 to 140 °C. This unique behavior is considered as the key factor of the better thermal stability of the Li 1-xNi 1/3Co 1/3Mn 1/3O 2 cathode materials.

  18. Broadening of the R(0) and P(2) Lines in the 13CO Fundamental by Helium Atoms from 300 K down to 12 K: Measurements and Comparison with Close-Coupling Calculations

    NASA Technical Reports Server (NTRS)

    Thibault, F.; Mantz, A. W.; Claveau, C.; Valentin, A.; Hurtmans, D.

    2007-01-01

    We present measurements of He-broadening parameters for the R(0) and O(2) lines in the fundamental band of 13CO at different temperatures between 12K and room temperature. The broadening parameters are determined, taking into account confinement narrowing, by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The pressure broadening cross sections are deduced and compared to close-coupling calculations and earlier results obtained for rotational transitions of 12 CO.

  19. A novel process for recycling and resynthesizing LiNi1/3Co1/3Mn1/3O2 from the cathode scraps intended for lithium-ion batteries.

    PubMed

    Zhang, Xihua; Xie, Yongbing; Cao, Hongbin; Nawaz, Faheem; Zhang, Yi

    2014-09-01

    To solve the recycling challenge for aqueous binder based lithium-ion batteries (LIBs), a novel process for recycling and resynthesizing LiNi1/3Co1/3Mn1/3O2 from the cathode scraps generated during manufacturing process is proposed in this study. Trifluoroacetic acid (TFA) is employed to separate the cathode material from the aluminum foil. The effects of TFA concentration, liquid/solid (L/S) ratio, reaction temperature and time on the separation efficiencies of the cathode material and aluminum foil are investigated systematically. The cathode material can be separated completely under the optimal experimental condition of 15vol.% TFA solution, L/S ratio of 8.0 mL g(-1), reacting at 40°C for 180 min along with appropriate agitation. LiNi1/3Co1/3Mn1/3O2 is successfully resynthesized from the separated cathode material by solid state reaction method. Several kinds of characterizations are performed to verify the typical properties of the resynthesized LiNi1/3Co1/3Mn1/3O2 powder. Electrochemical tests show that the initial charge and discharge capacities of the resynthesized LiNi1/3Co1/3Mn1/3O2 are 201 mAh g(-)(1) and 155.4 mAh g(-1) (2.8-4.5 V, 0.1C), respectively. The discharge capacity remains at 129 mAh g(-1) even after 30 cycles with a capacity retention ratio of 83.01%. PMID:24973865

  20. REVEALING THE PHYSICAL PROPERTIES OF MOLECULAR GAS IN ORION WITH A LARGE-SCALE SURVEY IN J = 2-1 LINES OF {sup 12}CO, {sup 13}CO, AND C{sup 18}O

    SciTech Connect

    Nishimura, Atsushi; Tokuda, Kazuki; Kimura, Kimihiro; Muraoka, Kazuyuki; Maezawa, Hiroyuki; Ogawa, Hideo; Onishi, Toshikazu; Dobashi, Kazuhito; Shimoikura, Tomomi; Mizuno, Akira; Fukui, Yasuo

    2015-01-01

    We present fully sampled ∼3' resolution images of {sup 12}CO(J = 2-1), {sup 13}CO(J = 2-1), and C{sup 18}O(J = 2-1) emission taken with the newly developed 1.85 m millimeter-submillimeter telescope over the entire area of the Orion A and B giant molecular clouds. The data were compared with J = 1-0 of the {sup 12}CO, {sup 13}CO, and C{sup 18}O data taken with the Nagoya 4 m telescope and the NANTEN telescope at the same angular resolution to derive the spatial distributions of the physical properties of the molecular gas. We explore the large velocity gradient formalism to determine the gas density and temperature using line combinations of {sup 12}CO(J = 2-1), {sup 13}CO(J = 2-1), and {sup 13}CO(J = 1-0) assuming a uniform velocity gradient and abundance ratio of CO. The derived gas density is in the range of 500 to 5000 cm{sup –3}, and the derived gas temperature is mostly in the range of 20 to 50 K along the cloud ridge with a temperature gradient depending on the distance from the star forming region. We found that the high-temperature region at the cloud edge faces the H II region, indicating that the molecular gas is interacting with the stellar wind and radiation from the massive stars. In addition, we compared the derived gas properties with the young stellar objects distribution obtained with the Spitzer telescope to investigate the relationship between the gas properties and the star formation activity therein. We found that the gas density and star formation efficiency are positively well correlated, indicating that stars form effectively in the dense gas region.

  1. SPATIALLY RESOLVED HCN J = 4-3 AND CS J = 7-6 EMISSION FROM THE DISK AROUND HD 142527

    SciTech Connect

    Van der Plas, G.; Casassus, S.; Perez, S.; Christiaens, V.; Ménard, F.; Thi, W. F.; Pinte, C.

    2014-09-10

    The disk around HD 142527 attracts a great amount of attention compared to others because of its resolved (sub-)millimeter dust continuum that is concentrated into the shape of a horseshoe toward the north of the star. In this Letter we present spatially resolved ALMA detections of the HCN J = 4-3 and CS J = 7-6 emission lines. These lines give us a deeper view into the disk compared to the (optically thicker) CO isotopes. This is the first detection of CS J = 7-6 coming from a protoplanetary disk. Both emission lines are azimuthally asymmetric and are suppressed under the horseshoe-shaped continuum emission peak. A possible mechanism for explaining the decrease under the horseshoe-shaped continuum is the increased opacity coming from the higher dust concentration at the continuum peak. Lower dust and/or gas temperatures and an optically thick radio-continuum reduce line emission by freezing out and shielding emission from the far side of the disk.

  2. First observations of CO and HCN on Neptune and Uranus at millimeter wavelengths and the implications for atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Marten, A.; Gautier, D.; Owen, T.; Sanders, D. B.; Matthews, H. E.; Atreya, S. K.; Tilanus, R. P. J.; Deane, J. R.

    1993-01-01

    Observations are presented which show that CO is present in both the troposphere and stratosphere of Neptune, whereas is confined to the Neptune stratosphere with a mean mole fraction in the 0.003-30 mbar pressure level range of 1.0 x 10 exp -9. CO is present in both the stratosphere and in the troposphere with a uniformly mixed model fraction of 1.2 x 10 exp -6. Upper limits of 1.0 x 10 exp -10 and 3.0 x 10 exp -8 mole fractions are derived for HCN and CO respectively on Uranus. The origin of these species in the atmosphere of Neptune and their nondetection in that of Uranus are discussed in detail. It is concluded that the most plausible scenario involves upward convection of CO and N2 from Neptune's deep interior and a failure of chemical equilibrium at deep atmospheric levels, allowing excess CO and presumably N2 to reach the upper atmosphere. Nondetection in Uranus may be explained by the lack of a significant internal heat source in the planet and consequent suppression of vertical convection.

  3. Self-, N2- and Ar-broadening and line mixing in HCN and C2H2

    NASA Technical Reports Server (NTRS)

    Pine, A. S.

    1993-01-01

    Self-, N2- and Ar-broadening coefficients were measured for the stretch-bend infrared combination bands nu-1 + nu-1/2 (4004/cm) of HCN and nu-1 + nu-1/5 (4091/cm) of C2H2, using a tunable difference-frequency laser. At atmospheric pressures, the Q branches of these bands exhibit significant rotational narrowing or line mixing. The broadening coefficients are fit with empirical rotationally inelastic collision rate laws, which are then used to model the line mixing in the overlapped Q-branch profiles. Simple energy gap fitting laws appear to be suitable for the shorter-range intermolecular quadrupole-quadrupole and induction forces, whereas an energy-corrected-sudden scaling law works better for the longer-range dipole-dipole and dipole-quadrupole collision partners. In all cases, the line-coupling coefficients are substantially reduced from the rotationally inelastic rates fit to the broadening coefficients, indicating that 35-70 percent of the broadening may be due to other collisional mechanisms such as cross-relaxation to the degenerate H state vibrational level.

  4. Submillimeter Observations of Titan: Global Measures of Stratospheric Temperature, CO, HCN, HC3N, and the Isotopic Ratios 12C/13C and 14N/15N

    NASA Astrophysics Data System (ADS)

    Gurwell, Mark A.

    2004-11-01

    Interferometric observations of the atmosphere of Titan were performed with the Submillimeter Array on two nights in 2004 February to investigate the global average vertical distributions of several molecular species above the tropopause. Rotational transitions of CO, isomers of HCN, and HC3N were simultaneously recorded. The abundance of CO is determined to be 51+/-4 parts per million (ppm), constant with altitude. The vertical profile of HCN is dependent on the assumed temperature but generally increases from 30 parts per billion at the condensation altitude (~83 km) to 5 ppm at ~300 km. Furthermore, the central core of the HCN emission is strong and can be reproduced only if the upper stratospheric temperature increases with altitude. The isotopic ratios are determined to be 12C/13C=132+/-25 and 14N/15N=94+/-13 assuming the Coustenis & Bézard temperature profile. If the Lellouch temperature profile is assumed, the ratios decrease to 12C/13C=108+/-20 and 14N/15N=72+/-9. The vertical profile of HC3N is consistent with that derived by Marten et al.

  5. Thermal formation of hydroxynitriles, precursors of hydroxyacids in astrophysical ice analogs: Acetone ((CH3)2Cdbnd O) and hydrogen cyanide (HCN) reactivity

    NASA Astrophysics Data System (ADS)

    Fresneau, Aurélien; Danger, Grégoire; Rimola, Albert; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry

    2015-11-01

    Reactivity in astrophysical environments is still poorly understood. In this contribution, we investigate the thermal reactivity of interstellar ice analogs containing acetone ((CH3)2CO), ammonia (NH3), hydrogen cyanide (HCN) and water (H2O) by means of infrared spectroscopy and mass spectrometry techniques, complemented by quantum chemical calculations. We show that no reaction occurs in H2O:HCN:(CH3)2CO ices. Nevertheless, HCN does indeed react with acetone once activated by NH3 into CN- to form 2-hydroxy-2-methylpropanenitrile (HOsbnd C(CH3)2sbnd CN), with a calculated activation energy associated with the rate determining step of about 51 kJ mol-1. This reaction inhibits the formation of 2-aminopropan-2-ol (HOsbnd C(CH3)2sbnd NH2) from acetone and NH3, even in the presence of water, which is the first step of the Strecker synthesis to form 2-aminoisobutyric acid (NH2C(CH3)2COOH). However, HOsbnd C(CH3)2sbnd CN formation could be part of an alternative chemical pathway leading to 2-hydroxy-2-methyl-propanoic acid (HOC(CH3)2COOH), which could explain the presence of hydroxy acids in some meteorites.

  6. 3, 3‧-sulfonyldipropionitrile: A novel electrolyte additive that can augment the high-voltage performance of LiNi1/3Co1/3Mn1/3O2/graphite batteries

    NASA Astrophysics Data System (ADS)

    Zheng, Xiangzhen; Huang, Tao; Pan, Ying; Wang, Wenguo; Fang, Guihuang; Ding, Kaining; Wu, Maoxiang

    2016-07-01

    Our study shows that 3, 3‧-sulfonyldipropionitrile (SDPN), as an electrolyte additive, can dramatically enhance the performance of LiNi1/3Co1/3Mn1/3O2/graphite lithium-ion batteries (LIBs) at high voltages (3.0-4.6 V vs. Li/Li+). After adding 0.2 wt% SDPN to the electrolytes; i.-e., 1.0 M LiPF6-EC/DMC/EMC, the capacity for the LiNi1/3Co1/3Mn1/3O2/graphite cell to retain power was significantly increased from 59.5% to 77.3% after only 100 cycles, which shows the promising application of SDPN at higher voltages. Density functional theory calculation results indicate that SDPN had reduced oxidative constancy compared to ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC). The effects of SDPN on cell performance are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The testing results indicate that the improvement in cycling activity could be ascribed to the thinner cathode electrolyte interface film originated from SDPN on the LIB using LiNi1/3Co1/3Mn1/3O2, which reduced the interfacial resistance at a high voltage, but also protected the decomposition of electrolytes and suppressed transition metal dissolution.

  7. Morphology and electrochemical performance of Li[Ni 1/3Co 1/3Mn 1/3]O 2 cathode material by a slurry spray drying method

    NASA Astrophysics Data System (ADS)

    Lin, Bin; Wen, Zhaoyin; Gu, Zhonghua; Huang, Shahua

    The spherical Li[Ni 1/3Co 1/3Mn 1/3]O 2 powders with appropriate porosity, small particle size and good particle size distribution were successfully prepared by a slurry spray drying method. The Li[Ni 1/3Co 1/3Mn 1/3]O 2 powders were characterized by XRD, SEM, ICP, BET, EIS and galvanostatic charge/discharge testing. The material calcined at 950 °C had the best electrochemical performance. Its initial discharge capacity was 188.9 mAh g -1 at the discharge rate of 0.2 C (32 mA g -1), and retained 91.4% of the capacity on going from 0.2 to 4 C rate. From the EIS result, it was found that the favorable electrochemical performance of the Li[Ni 1/3Co 1/3Mn 1/3]O 2 cathode material was primarily attributed to the particular morphology formed by the spray drying process which was favorable for the charge transfer during the deintercalation and intercalation cycling.

  8. Uncovering a facile large-scale synthesis of LiNi1/3Co1/3Mn1/3O2 nanoflowers for high power lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Hua, Wei-Bo; Guo, Xiao-Dong; Zheng, Zhuo; Wang, Yan-Jie; Zhong, Ben-He; Fang, Baizeng; Wang, Jia-Zhao; Chou, Shu-Lei; Liu, Heng

    2015-02-01

    Developing advanced electrode materials that deliver high energy at ultra-fast charge and discharge rates are very crucial to meet an increasing large-scale market demand for high power lithium ion batteries (LIBs). A three-dimensional (3D) nanoflower structure is successfully developed in the large-scale synthesis of LiNi1/3Co1/3Mn1/3O2 material for the first time. The fast co-precipitation is the key technique to prepare the nanoflower structure in our method. After heat treatment, the obtained LiNi1/3Co1/3Mn1/3O2 nanoflowers (NL333) pronouncedly present a pristine flower-like nano-architecture and provide fast pathways for the transport of Li-ions and electrons. As a cathode material in a LIB, the prepared NL333 electrode demonstrates an outstanding high-rate capability. Particularly, in a narrow voltage range of 2.7-4.3 V, the discharge capacity at an ultra-fast charge-discharge rate (20C) is up to 126 mAh g-1, which reaches 78% of that at 0.2C, and is much higher than that (i.e., 44.17%) of the traditional bulk LiNi1/3Co1/3Mn1/3O2.

  9. Crystal and electronic structure analysis and thermodynamic stabilities for electrochemically or chemically delithiated Li1.2-xMn0.54Ni0.13Co0.13O2

    NASA Astrophysics Data System (ADS)

    Ishida, Naoya; Tamura, Norihide; Kitamura, Naoto; Idemoto, Yasushi

    2016-07-01

    The Li1.2-xMn0.54Ni0.13Co0.13O2 were synthesized by chemical or electrochemical delithiation. The characterization by using the XRD, ICP, synchrotron XRD and thermodynamic measurements were performed for pristine and delithiated compounds. The measured lithium compositions for chemically delithiated Li1.2-xMn0.54Ni0.13Co0.13O2 showed the values of x = 0.31, 0.43, and 0.88, and were nearly the same as the electrochemically delithiated cathodes at 4.3 V, 4.5 V, and 4.8 V, respectively. The crystal and electronic structures for pristine and delithiated samples were analyzed by the Rietveld method using synchrotron X-ray diffraction. As a result, many structural parameters resembled between chemically and electrochemically delithiations up to x ≈ 0.5. Above x ≈ 0.5, the distortion parameters, λ and σ2, and the electronic structures for electrochemically delithiated materials were not coincide with those for corresponding chemically delithiated one. Thermodynamic stabilities of the materials about x ≈ 0.9 were enhanced for electrochemically delithiation. The chemically delithiation of the Li1.2Mn0.54Ni0.13Co0.13O2 enabled the reproduction of the charged active materials up to 4.5 V by using the NO2BF4 oxidizer.

  10. Highly enhanced low temperature discharge capacity of LiNi1/3Co1/3Mn1/3O2 with lithium boron oxide glass modification

    NASA Astrophysics Data System (ADS)

    Tan, ShuangYuan; Wang, Lei; Bian, Liang; Xu, JinBao; Ren, Wei; Hu, PengFei; Chang, AiMin

    2015-03-01

    Although lithium ion battery is known to be an excellent renewable energy provider in electronic markets further application of it has been limited by its notoriously poor performance at low temperature, especially below -20 °C. In this paper, the electrochemical performance of the LiNi1/3Co1/3Mn1/3O2 cathode materials coated by lithium boron oxide (LBO) glass was investigated at a temperature range from 20 to -40 °C. The results show that the LBO coating not only helps to improve the discharge capacity of LiNi1/3Co1/3Mn1/3O2 at room temperature but also increase the discharge capacity retention of the LiNi1/3Co1/3Mn1/3O2 from 22.5% to 57.8% at -40 °C. Electrochemical impedance spectra results reveal that the LBO coating plays an important role in reducing the charge-transfer resistance on the electrolyte-electrode interfaces and improving lithium ion diffusion coefficients. The mechanism associated with the change of the structure and electrical properties are discussed in detail.

  11. Studying the Outflow-Core Interaction with ALMA Cycle 1 Observations of the HH46/47 Molecular Outflow

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Arce, H. G.; Mardones, D.; Dunham, M. M.; Garay, G.; Noriega-Crespo, A.; Corder, S.; Offner, S.

    2015-12-01

    We present preliminary analysis of ALMA cycle 1 12m array 12CO /13CO /C18O data of the HH 46/47 molecular outflow. 13CO and C18O trace relatively denser outflow material than 12CO and allow us to trace the outflow to lower velocities than what it possible using only the 12CO emission. Interestingly, the cavity wall of the red lobe can be seen at velocity as low as 0.2 km/s. Using C18O, we are now able to estimate the optical depth of 13CO, and then use the corrected 13CO emission to further and better correct the 12CO emission and estimate the mass, momentum, and kinetic energy of the outflow. Moreover, C18O reveals a flattened rotational structure at the center, likely to be a rotational envelope infalling onto an inner Keplerian disk.

  12. Investigating the impact of light and water status on the exchange of COS, 13CO2, CO18O and H218O from bryophytes

    NASA Astrophysics Data System (ADS)

    Gimeno, Teresa; Royles, Jessica; Ogee, Jerome; Jones, Samuel; Burlett, Regis; West, Jason; Sauze, Joana; Wohl, Steven; Genty, Bernard; Griffiths, Howard; Wingate, Lisa

    2016-04-01

    Terrestrial surfaces are often covered by photoautotrophic communities that play a significant role in the biological fixation of C and N at the global scale. Bryophytes (mosses, liverworts and hornworts) are key members in these communities and are especially adapted to thrive in hostile environments, by growing slowly and surviving repeated dehydration events. Consequently, bryophyte communities can be extremely long-lived (>1500yrs) and can serve as valuable records of historic climate change. In particular the carbon and oxygen isotope compositions of mosses can be used as powerful proxies describing how growing season changes in atmospheric CO2 and rainfall have changed in the distant past over the land surface. Interpreting the climate signals of bryophyte biomass requires a robust understanding of how changes in photosynthetic activity and moisture status regulate the growth and isotopic composition of bryophyte biomass. Thus theoretical models predicting how changes in isotopic enrichment and CO2 discrimination respond to dehydration and rehydration are used to tease apart climatic and isotopic source signals. Testing these models with high resolution datasets obtained from new generation laser spectrometers can provide more information on how these plants that lack stomata cope with water loss. In addition novel tracers such as carbonyl sulfide (COS) can also be measured at high resolution and precision (<5ppt) and used to constrain understanding of diffusional and enzymatic limitations during dehydration and rehydration events in the light and the dark. Here, we will present for the first time simultaneous high-resolution chamber measurements of COS, 13CO2, CO18O and H218O fluxes by a bryophyte species (Marchantia sp.) in the light and during the dark, through complete desiccation cycles. Our measurements consistently reveal a strong enrichment dynamic in the oxygen isotope composition of transpired water over the dessication cycle that caused an increase

  13. A novel process for recycling and resynthesizing LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} from the cathode scraps intended for lithium-ion batteries

    SciTech Connect

    Zhang, Xihua; Xie, Yongbing; Cao, Hongbin; Nawaz, Faheem; Zhang, Yi

    2014-09-15

    Highlights: • A simple process to recycle cathode scraps intended for lithium-ion batteries. • Complete separation of the cathode material from the aluminum foil is achieved. • The recovered aluminum foil is highly pure. • LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} is directly resynthesized from the separated cathode material. - Abstract: To solve the recycling challenge for aqueous binder based lithium-ion batteries (LIBs), a novel process for recycling and resynthesizing LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} from the cathode scraps generated during manufacturing process is proposed in this study. Trifluoroacetic acid (TFA) is employed to separate the cathode material from the aluminum foil. The effects of TFA concentration, liquid/solid (L/S) ratio, reaction temperature and time on the separation efficiencies of the cathode material and aluminum foil are investigated systematically. The cathode material can be separated completely under the optimal experimental condition of 15 vol.% TFA solution, L/S ratio of 8.0 mL g{sup −1}, reacting at 40 °C for 180 min along with appropriate agitation. LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} is successfully resynthesized from the separated cathode material by solid state reaction method. Several kinds of characterizations are performed to verify the typical properties of the resynthesized LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} powder. Electrochemical tests show that the initial charge and discharge capacities of the resynthesized LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} are 201 mAh g{sup −1} and 155.4 mAh g{sup −1} (2.8–4.5 V, 0.1 C), respectively. The discharge capacity remains at 129 mAh g{sup −1} even after 30 cycles with a capacity retention ratio of 83.01%.

  14. Structural Insights into the Functional Role of the Hcn Sub-domain of the Receptor-Binding Domain of the Botulinum Neurotoxin Mosaic Serotype C/D

    SciTech Connect

    Zhang, Yanfeng; Gardberg, Anna; Edwards, Tom E.; Sankaran, Banumathi; Robinson, Howard; Varnum, Susan M.; Buchko, Garry W.

    2013-07-01

    Botulinum neurotoxin (BoNT), the causative agent of the deadly neuroparalytic disease botulism, is the most poisonous protein known for humans. Produced by different strains of the anaerobic bacterium Clostridium botulinum, BoNT effects cellular intoxication via a multistep mechanism executed by the three modules of the activated protein. Endocytosis, the first step of cellular intoxication, is triggered by the ~50 kDa, heavy-chain receptor-binding module (HCR) that is specific for a ganglioside and a protein receptor on neuronal cell surfaces. This dual receptor recognition mechanism between BoNT and the host cell’s membrane is well documented and occurs via specific intermolecular interactions with the C-terminal sub-domain, Hcc, of BoNT-HCR. The N-terminal sub-domain of BoNT-HCR, Hcn, comprises ~50% of BoNT-HCR and adopts a B-sheet jelly roll fold. While suspected in assisting cell surface recognition, no unambiguous function for the Hcn sub-domain in BoNT has been indentified. To obtain insights into the potential function of the Hcn sub-domain in BoNT, the first crystal structure of a BoNT with an organic ligand bound to the Hcn sub-domain has been obtained. Here, we describe the crystal structure of BoNT/CD-HCR determined at 1.70 Å resolution with a tetraethylene glycol (PG4) molecule bound in an hydrophobic cleft between B-strands in the B-sheet jelly fold roll of the Hcn sub-domain. The molecule is completely engulfed in the cleft, making numerous hydrophobic (Y932, S959, W966, and D1042) and hydrophilic (S935, W977, L979, N1013, and I1066) contacts with the protein’s side chain and backbone that may mimic in vivo interactions with the phospholipid membranes on neuronal cell surfaces. A sulfate ion was also observed bound to residues T1176, D1177, K1196, and R1243 in the Hcc sub-domain of BoNT/CD-HCR. In the crystal structure of a similar protein, BoNT/D-HCR, a sialic acid

  15. Formation of analogs of cometary nitrogen-rich refractory organics from thermal degradation of tholin and HCN polymer

    NASA Astrophysics Data System (ADS)

    Bonnet, Jean-Yves; Quirico, Eric; Buch, Arnaud; Thissen, Roland; Szopa, Cyril; Carrasco, Nathalie; Cernogora, Guy; Fray, Nicolas; Cottin, Hervé; Roy, Lena Le; Montagnac, Gilles; Dartois, Emmanuel; Brunetto, Rosario; Engrand, Cécile; Duprat, Jean

    2015-04-01

    Nitrogen-rich refractory organics are scarce phases recovered as a fraction of stratospheric IDPs and constitute the bulk of the organic matter of some ultracarbonaceous Antarctic micrometeorites. They are likely formed under very specific conditions within a nitrogen-rich environment and may provide valuable clues on the origin of the population of interplanetary dusts accreted by Earth. In this study, we produced relevant analogs of such refractory organics characterized in three ultracarbonaceous Antarctic micrometeorites, starting from the carbonization of an HCN polymer and a tholin. Indeed, carbonization is a process that can increase the polyaromatic character toward a structure similar to that observed in these cosmomaterials. Both these precursors were degraded in an Ar atmosphere at 300, 500, 700 and 1000 °C over ∼1 h and characterized by elemental analysis, micro-FTIR and Raman micro-spectroscopy (at 244 and 514 nm excitation wavelengths). Our results show that the precursors evolve along distinct chemical and structural pathways during carbonization and that the influence of the precursor structure is still very strong at 1000 °C. Interestingly, these different carbonization routes appear in the spectral characteristics of the G and D bands of their Raman spectra. Several of the residues present chemical and structural similarities with three recently studied ultracarbonaceous micrometeorites (Dobrica et al. [2011]. Meteorit. Planet. Sci. 46, 1363; Dartois et al. [2013]. Icarus 224, 243) and with N-rich inclusions in stratospheric IDPs. However, the residues do not simultaneously account for the carbon structure (Raman) and the chemical composition (IR, N/C ratio). This indicates that the precursors and/or heating conditions in our experiments are not fully relevant. Despite this lack of full relevancy, the formation of a polyaromatic structure fairly similar to that of UCAMMs and IDPs suggests that the origin of N-rich refractory organics lies in a

  16. THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. IV. THE NGC 1333 CLOUD IN PERSEUS IN CO J = 2-1 AND {sup 13}CO J = 2-1

    SciTech Connect

    Bieging, John H.; Revelle, Melissa; Peters, William L.

    2014-09-01

    We mapped the NGC 1333 section of the Perseus Molecular Cloud in the J = 2-1 emission lines of {sup 12}CO and {sup 13}CO over a 50' × 60' region (3.4 × 4.1 pc at the cloud distance of 235 pc), using the Arizona Radio Observatory Heinrich Hertz Submillimeter Telescope. The angular resolution is 38'' (0.04 pc) and velocity resolution is 0.3 km s{sup –1}. We compare our velocity moment maps with known positions of young stellar objects (YSOs) and (sub)millimeter dust continuum emission. The CO emission is brightest at the center of the cluster of YSOs, but is detected over the full extent of the mapped region at ≥10 × rms. The morphology of the CO channel maps shows a kinematically complex structure, with many elongated features extending from the YSO cluster outward by ∼1 pc. One notable feature appears as a narrow serpentine structure that curves and doubles back, with a total length of ∼3 pc. The {sup 13}CO velocity channel maps show evidence for many low-density cavities surrounded by partial shell-like structures, consistent with previous studies. Maps of the velocity moments show localized effects of bipolar outflows from embedded YSOs, as well as a large-scale velocity gradient around the central core of YSOs, suggestive of large-scale turbulent cloud motions determining the location of current star formation. The CO/{sup 13}CO intensity ratios show the distribution of the CO opacity, which exhibits a complex kinematic structure. Identified YSOs are located mainly at the positions of greatest CO opacity. The maps are available for download as FITS files.

  17. Stability and breakdown of Ca{sup 13}CO{sub 3} melt associated with formation of {sup 13}C-diamond in static high pressure experiments up to 43 GPa and 3900 K

    SciTech Connect

    Spivak, A.V.; Litvin, Yu.A.; Ovsyannikov, S.V.; Dubrovinskaia, N.A.; Dubrovinsky, L.S.

    2012-07-15

    Melting of calcium carbonate Ca{sup 13}CO{sub 3}, stability of the melt and its decomposition were studied in static high pressure experiments at pressures of 11-43 GPa and temperatures of 1600-3900 K using diamond anvil cell technique with laser heating. We observed formation of {sup 13}C-graphite (below 16 GPa) and {sup 13}C-diamond (between 16 and 43 GPa) on decomposition of the Ca{sup 13}CO{sub 3} melt at temperatures above 3400 K. At temperatures below 3400 K congruent melting of calcium carbonate was confirmed. The experimental results were applied to construction of the phase diagram of CaCO{sub 3} up to 43 GPa and 3900 K focusing at the melting curve of calcium carbonate and the decomposition phase boundary of CaCO{sub 3} melt. - Graphical abstract: Highlights: Black-Right-Pointing-Pointer Phase states of CaCO{sub 3} were studied at P=11-43 GPa and T=1600-3900 K. Black-Right-Pointing-Pointer {sup 13}C-diamond easily crystallizes in carbonate-carbon (Ca{sup 13}CO{sub 3-}{sup 13}C-graphite) melt-solutions. Black-Right-Pointing-Pointer Ca-carbonate melts congruently that was observed in experiments in DAC with laser heating. Black-Right-Pointing-Pointer Decomposition of CaCO{sub 3} melt, indicated by formation of graphite and/or diamond. Black-Right-Pointing-Pointer Decomposition of CaCO{sub 3} was observed at temperatures above 3400 K in the pressure interval studied.

  18. Structural and Electrochemical Study of Hierarchical LiNi(1/3)Co(1/3)Mn(1/3)O2 Cathode Material for Lithium-Ion Batteries.

    PubMed

    Li, Li; Wang, Lecai; Zhang, Xiaoxiao; Xie, Man; Wu, Feng; Chen, Renjie

    2015-10-01

    In this study, a facile nanoetching-template route is developed to synthesize porous nanomicrohierarchical LiNi1/3Co1/3Mn1/3O2 microspheres with diameters below 1.5 μm, using porous CoMnO3 binary oxide microspheres as the template. The unique morphology of CoMnO3 template originates from the contraction effect during the oxidative decomposition of Ca0.2Mn0.4Co0.4CO3 precursors and is further improved by selectively removing calcium carbonate with a nanoetching process after calcination. The as-synthesized LiNi1/3Co1/3Mn1/3O2 microsphere, composed of numerous primary particles and pores with size of dozens of nanometers, illustrates a well-assembled porous nanomicrohierarchical structure. When used as the cathode material for lithium-ion batteries, the as-synthesized microspheres exhibit remarkably enhanced electrochemical performances with higher capacity, excellent cycling stability, and better rate capability, compared with the bulk counterpart. Specifically, hierarchical LiNi1/3Co1/3Mn1/3O2 achieves a high discharge capacity of 159.6 mA h g(-1) at 0.2 C with 98.7% capacity retention after 75 cycles and 133.2 mA h g(-1) at 1 C with 90% capacity retention after 100 cycles. A high discharge capacity of 135.5 mA h g(-1) even at a high current of 750 mA g(-1) (5 C) is also achieved. The nanoetching-template method can provide a general approach to improve cycling stability and rate capability of high capacity cathode materials for lithium-ion batteries. PMID:26371492

  19. Synthesis and performance of Li[(Ni1/3Co1/3Mn1/3)(1-x)Mgx]O2 prepared from spent lithium ion batteries.

    PubMed

    Weng, Yaqing; Xu, Shengming; Huang, Guoyong; Jiang, Changyin

    2013-02-15

    To reduce cost and secondary pollution of spent lithium ion battery (LIB) recycling caused by complicated separation and purification, a novel simplified recycling process is investigated in this paper. Removal of magnesium is a common issue in hydrometallurgy process. Considering magnesium as an important additive in LIB modification, tolerant level of magnesium in leachate is explored as well. Based on the novel recycling technology, Li[(Ni(1/3)Co(1/3)Mn(1/3))(1-x)Mg(x)]O(2) (0 ≤ x ≤ 0.05) cathode materials are achieved from spent LIB. Tests of XRD, SEM, TG-DTA and so on are carried out to evaluate material properties. Electrochemical test shows an initial charge and discharge capacity of the regenerated LiNi(1/3)Co(1/3)Mn(1/3)O(2) to be 175.4 mAh g(-1) and 152.7 mAh g(-1) (2.7-4.3 V, 0.2C), respectively. The capacity remains 94% of the original value after 50 cycles (2.7-4.3 V, 1C). Results indicate that presence of magnesium up to x=0.01 has no significant impact on overall performance of Li[(Ni(1/3)Co(1/3)Mn(1/3))(1-x)Mg(x)]O(2). As a result, magnesium level as high as 360 mg L(-1) in leachate remains tolerable. Compared with conventional limitation of magnesium content, the elimination level of magnesium exceeded general impurity-removal requirement. PMID:23298741

  20. First-principles study of native point defects in LiNi(1/3)Co(1/3)Mn(1/3)O2 and Li2MnO3.

    PubMed

    Park, Min Sik

    2014-08-21

    We have studied native point defects in the layered oxides of LiNi1/3Co1/3Mn1/3O2 and Li2MnO3, the promising cathode materials for rechargeable Li-ion batteries for the application of high lithium capacity, by performing first-principles calculations. Through the calculations of formation energies for native point defects in LiNi1/3Co1/3Mn1/3O2, it was found that the Ni vacancy and the LiNi antisite are the most dominant defects, which shows a good agreement with previous experiments. Contrary to the previous experimental analysis, however, the NiLi antisite defect is not dominant, even though both Ni and Li ions have a similar ionic radius. In Li2MnO3, the LiMn antisite defect is dominant under the O-rich and Mn-poor condition. In contrast, the MnLi antisite, the Li vacancy in the Li layer, and the oxygen vacancy are dominant at the chemical potential of the boundary in equilibrium with Li2O. To enhance the migration of Li ions for achieving high power, the experimental syntheses of LiNi1/3Co1/3Mn1/3O2 under the Ni-rich condition and Li2MnO3 under O-rich and Mn-poor condition were suggested. For Li2MnO3 suffering from poor electronic conductivity, it was found that the electronic conductivity can be increased by p- and n-type extrinsic doping under the O-rich and Mn-poor condition and the chemical potential of the boundary coexisting with Li2O, respectively, without losing the Li ion conductivity. PMID:25001849

  1. Persistent State-of-Charge Heterogeneity in Relaxed, Partially Charged Li1- x Ni1/3 Co1/3 Mn1/3 O2 Secondary Particles.

    PubMed

    Gent, William E; Li, Yiyang; Ahn, Sungjin; Lim, Jongwoo; Liu, Yijin; Wise, Anna M; Gopal, Chirranjeevi Balaji; Mueller, David N; Davis, Ryan; Weker, Johanna Nelson; Park, Jin-Hwan; Doo, Seok-Kwang; Chueh, William C

    2016-08-01

    Ex situ transmission X-ray microscopy reveals micrometer-scale state-of-charge heterogeneity in solid-solution Li1- x Ni1/3 Co1/3 Mn1/3 O2 secondary particles even after extensive relaxation. The heterogeneity generates overcharged domains at the cutoff voltage, which may accelerate capacity fading and increase impedance with extended cycling. It is proposed that optimized secondary structures can minimize the state-of-charge heterogeneity by mitigating the buildup of nonuniform internal stresses associated with volume changes during charge. PMID:27187238

  2. APERTURE SYNTHESIS OBSERVATIONS OF CO, HCN, AND 89 GHz CONTINUUM EMISSION TOWARD NGC 604 IN M33: SEQUENTIAL STAR FORMATION INDUCED BY A SUPERGIANT H II REGION

    SciTech Connect

    Miura, Rie; Okumura, Sachiko K.; Kurono, Yasutaka; Nakanishi, Kouichiro; Tosaki, Tomoka; Tamura, Yoichi; Kuno, Nario; Kawabe, Ryohei; Sakamoto, Seiichi; Hasegawa, Takashi

    2010-12-01

    We present the results from new Nobeyama Millimeter Array observations of CO(1-0), HCN(1-0), and 89 GHz continuum emission toward NGC 604, known as the supergiant H II region in the nearby galaxy M33. Our high spatial resolution images (4.''2 x 2.''6, corresponding to 17 pc x 11 pc physical size) of CO emission allowed us to uncover 10 individual molecular clouds that have masses of (0.8-7.4) x10{sup 5} M{sub sun} and sizes of 5-29 pc, comparable to those of typical Galactic giant molecular clouds. Moreover, we detected for the first time HCN emission in the two most massive clouds and 89 GHz continuum emission at the rims of the 'H{alpha} shells'. The HCN and 89 GHz continuum emission are offset from the CO peak and are distributed in the direction of the central cluster. Three out of ten CO clouds are well correlated with the H{alpha} shells both in spatial and velocity domains, implying an interaction between molecular gas and the expanding H II region. The CO clouds show varieties in star formation efficiencies (SFEs), which are estimated from the 89 GHz emission and combination of H{alpha} and Spitzer 24 {mu}m data. Furthermore, we found that the SFEs decrease with increasing projected distance measured from the heart of the central OB star cluster in NGC 604, suggesting radial changes in the evolutionary stages of the molecular clouds in the course of stellar cluster formation. Our results provide further support to the picture of sequential star formation in NGC 604 initially proposed by Tosaki et al. with the higher spatially resolved molecular clouds, in which an isotropic expansion of the H II region pushes gases outward, which accumulates to form dense molecular clouds, and then induces massive star formations.

  3. HCN, a triple-resonance NMR technique for selective observation of histidine and tryptophan side chains in 13C/15N-labeled proteins.

    PubMed

    Sudmeier, J L; Ash, E L; Günther, U L; Luo, X; Bullock, P A; Bachovchin, W W

    1996-12-01

    HCN, a new 3D NMR technique for stepwise coherence transfer from 1H to 13C to 15N and reverse through direct spin couplings 1JCH and 1JCN, is presented as a method for detection and assignment of histidine and tryptophan side-chain 1H, 13C, and 15N resonances in uniformly 13C/15N-labeled proteins. Product-operator calculations of cross-peak volumes vs adjustable delay tau 3 were employed for determination of optimal tau 3. For the phosphatidylinositol 3-kinase (PI3K SH3 domain, MW = 9.6 kD) at pH 6, H(C)N, the 1H/15N projection, produced observable cross peaks within 20 min. and was completely selective for the single tryptophan and single histidine. The 3D HCN experiment yielded well-defined cross peaks in 20 h for the 13C/15N-labeled origin-specific DNA binding domain from simian virus 40 T-antigen (T-ag-OBD131-259, MW = 15.4 kD) at pH 5.5. Resonances from all six histidines in T-ag-OBD were observed, and 11 of the 12 1H and 13C chemical shifts and 10 of the 12 15N chemical shifts were determined. The 13C dimension proved essential in assignment of the multiply overlapping 1H and 15N resonances. From the spectra recorded at a single pH, three of the imidazoles were essentially neutral and the other three were partially protonated (22-37%). HCN yielded strong cross peaks after 18 h on a 2.0 mM sample of phenylmethanesulfonyl fluoride (PMSF)-inhibited alpha-lytic protease (MW = 19.8 kD) at pH 4.4. No spectra have been obtained, however, of native or boronic acid-inhibited alpha-lytic protease after 18 h at various temperatures ranging from 5 to 55 degrees C, probably due to efficient relaxation of active-site imidazole 1H and/or 15N nuclei. PMID:8995843

  4. HCN, A Triple-Resonance NMR Technique for Selective Observation of Histidine and Tryptophan Side Chains in 13C/ 15N-Labeled Proteins

    NASA Astrophysics Data System (ADS)

    Sudmeier, James L.; Ash, Elissa L.; Günther, Ulrich L.; Luo, Xuelian; Bullock, Peter A.; Bachovchin, William W.

    1996-12-01

    HCN, a new 3D NMR technique for stepwise coherence transfer from1H to13C to15N and reverse through direct spin couplings1JCHand1JCN, is presented as a method for detection and assignment of histidine and tryptophan side-chain1H,13C, and15N resonances in uniformly13C/15N-labeled proteins. Product-operator calculations of cross-peak volumes vs adjustable delay τ3were employed for determination of optimal τ3. For the phosphatidylinositol 3-kinase (PI3K SH3 domain, MW = 9.6 kD) at pH 6, H(C)N, the1H/15N projection, produced observable cross peaks within 20 min. and was completely selective for the single tryptophan and single histidine. The 3D HCN experiment yielded well-defined cross peaks in 20 h for the13C/15N-labeled origin-specific DNA binding domain from simian virus 40 T-antigen (T-ag-OBD131-259, MW = 15.4 kD) at pH 5.5. Resonances from all six histidines in T-ag-OBD were observed, and 11 of the 121H and13C chemical shifts and 10 of the 1215N chemical shifts were determined. The13C dimension proved essential in assignment of the multiply overlapping1H and15N resonances. From the spectra recorded at a single pH, three of the imidazoles were essentially neutral and the other three were partially protonated (22-37%). HCN yielded strong cross peaks after 18 h on a 2.0 mMsample of phenylmethanesulfonyl fluoride (PMSF)-inhibited α-lytic protease (MW = 19.8 kD) at pH 4.4. No spectra have been obtained, however, of native or boronic acid-inhibited α-lytic protease after 18 h at various temperatures ranging from 5 to 55°C, probably due to efficient relaxation of active-site imidazole1H and/or15N nuclei.

  5. Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH, 18OH, O I, HCN, and NH3

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    Full range Herschel/PACS spectroscopy of the (ultra)luminous infrared galaxies NGC 4418 and Arp 220, observed as part of the SHINING key programme, reveals high excitation in H2O, OH, HCN, and NH3. In NGC 4418, absorption lines were detected with Elower > 800 K (H2O), 600 K (OH), 1075 K (HCN), and 600 K (NH3), while in Arp 220 the excitation is somewhat lower. While outflow signatures in moderate excitation lines are seen in Arp 220 as have been seen in previous studies, in NGC 4418 the lines tracing its outer regions are redshifted relative to the nucleus, suggesting an inflow with Ṁ ≲ 12 M⊙ yr-1. Both galaxies have compact and warm (Tdust ≳ 100 K) nuclear continuum components, together with a more extended and colder component that is much more prominent and massive in Arp 220. A chemical dichotomy is found in both sources: on the one hand, the nuclear regions have high H2O abundances, ~10-5, and high HCN/H2O and HCN/NH3 column density ratios of 0.1-0.4 and 2-5, respectively, indicating a chemistry typical of evolved hot cores where grain mantle evaporation has occurred. On the other hand, the high OH abundance, with OH/H2O ratios of ~0.5, indicates the effects of X-rays and/or cosmic rays. The nuclear media have high surface brightnesses (≳1013 L⊙/kpc2) and are estimated to be very thick (NH ≳ 1025 cm-2). While NGC 4418 shows weak absorption in H218O and 18OH, with a 16O-to-18O ratio of ≳250-500, the relatively strong absorption of the rare isotopologues in Arp 220 indicates 18O enhancement, with 16O-to-18O of 70-130. Further away from the nuclear regions, the H2O abundance decreases to ≲10-7 and the OH/H2O ratio is reversed relative to the nuclear region to 2.5-10. Despite the different scales and morphologies of NGC 4418, Arp 220, and Mrk 231, preliminary evidence is found for an evolutionary sequence from infall, hot-core like chemistry, and solar oxygen isotope ratio to high velocity outflow, disruption of the hot core chemistry and

  6. Does the spatial confinement influence the electric properties and cooperative effects of the hydrogen bonded systems? HCN chains as a case study

    NASA Astrophysics Data System (ADS)

    Roztoczyńska, Agnieszka; Kozłowska, Justyna; Lipkowski, Paweł; Bartkowiak, Wojciech

    2014-07-01

    In this Letter the impact of orbital compression on the energetic and electric properties as well as cooperative effects in the hydrogen bonded systems was investigated. The model (HCN)n chains, with n = 2-5, were chosen as a case study. The effect of spatial restriction was modeled by the harmonic oscillator potential. Moreover, changes in the structural parameters in the presence of model confining potential were also analyzed. All calculations were performed using the MP2 method. The obtained results demonstrated inter alia that the spatial confinement significantly influences the analyzed properties.

  7. Quantum reactive scattering studies of the CN + H 2 → HCN + H reaction: the role of the non-reactive CN bond

    NASA Astrophysics Data System (ADS)

    Takayanagi, Toshiyuki; Schatz, George C.

    1997-02-01

    An extended version of the rotating-bond approximation (RBA) has been developed to study the title reaction, in which CN stretching is added to usual CH stretching and bend degrees of freedom in a coupled channel expansion. Calculations have been done on potential energy surfaces developed by Sun and Bowman (SB) and by ter Horst, Schatz, and Harding (TSH). The HCN vibrational product state distribution calculated on TSH surface shows significant population in both CH and CN stretching, indicating that the CN bond is not a spectator.

  8. Ion binding in the Open HCN Pacemaker Channel Pore: Fast Mechanisms to Shape “Slow” Channels

    PubMed Central

    Lyashchenko, Alex K.; Tibbs, Gareth R.

    2008-01-01

    IH pacemaker channels carry a mixed monovalent cation current that, under physiological ion gradients, reverses at ∼−34 mV, reflecting a 4:1 selectivity for K over Na. However, IH channels display anomalous behavior with respect to permeant ions such that (a) open channels do not exhibit the outward rectification anticipated assuming independence; (b) gating and selectivity are sensitive to the identity and concentrations of externally presented permeant ions; (c) the channels' ability to carry an inward Na current requires the presence of external K even though K is a minor charge carrier at negative voltages. Here we show that open HCN channels (the hyperpolarization-activated, cyclic nucleotide sensitive pore forming subunits of IH) undergo a fast, voltage-dependent block by intracellular Mg in a manner that suggests the ion binds close to, or within, the selectivity filter. Eliminating internal divalent ion block reveals that (a) the K dependence of conduction is mediated via K occupancy of site(s) within the pore and that asymmetrical occupancy and/or coupling of these sites to flux further shapes ion flow, and (b) the kinetics of equilibration between K-vacant and K-occupied states of the pore (10–20 μs or faster) is close to the ion transit time when the pore is occupied by K alone (∼0.5–3 μs), a finding that indicates that either ion:ion repulsion involving Na is adequate to support flux (albeit at a rate below our detection threshold) and/or the pore undergoes rapid, permeant ion-sensitive equilibration between nonconducting and conducting configurations. Biophysically, further exploration of the Mg site and of interactions of Na and K within the pore will tell us much about the architecture and operation of this unusual pore. Physiologically, these results suggest ways in which “slow” pacemaker channels may contribute dynamically to the shaping of fast processes such as Na-K or Ca action potentials. PMID:18270171

  9. Physicochemical characteristics of poly(vinylidene fluoride-hexafluoropropylene)-alumina for mesocarbon microbeads versus LiNi1/3Mn1/3Co1/3O2 Li-ion polymer cells

    NASA Astrophysics Data System (ADS)

    Manikandan, P.; Kousalya, S.; Periasamy, P.

    2013-10-01

    Membranes based on the composite gel polymer electrolyte (CGPE) system have been prepared through the solution casting method using poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP)), nano-sized alumina ceramics (Al2O3) and 1 M LiCF3SO3 salt dissolved in the mixture of (1:1) ethylene carbonate, dimethyl carbonate (EC+DMC) solvents. Physicochemical characteristics viz., structural, electrochemical properties of these membranes have been analyzed. The optimum composition of 10 wt% Al2O3 with (P(VdF-HFP)) and 1 M LiCF3SO3 in EC+DMC showed a higher ionic conductivity of 7.1047×10-3 S cm-1, electrochemical stability of 4.9 V (CGPE-10, 30 °C) which can be attributed to honey-comb structure. This Li/CGPE-10/LiNi1/3Mn1/3Co1/3O2 cell delivered significant enhancement in charge-discharge studies viz., 186 mA h g-1 (1st) and good capacity retention ˜90% (50th) in the voltage range 2.5-4.6 V at 0.1 C rate. Also, corresponding Li-ion polymer cell (MCMB/CGPE-10/LiNi1/3Mn1/3Co1/3O2) yielded proportionate 2.38 mA h and the capacity retention ˜95% at the 50th cycle.

  10. Structure and Electrochemistry of LiNi1/3Co1/3-yMyMn1/3O2 (M=Ti, Al, Fe) Positive Electrode Materials

    SciTech Connect

    Wilcox, James; Patoux, Sebastien; Doeff, Marca

    2009-01-14

    A series of materials based on the LiNi1/3Co1/3-yMyMn1/3O2 (M = Ti,Al,Fe) system has been synthesized and examined structurally and electrochemically. It is found that the changes in electrochemical performance depend highly on the nature of the substituting atom and its effect on the crystal structure. Substitution with small amounts of Ti4+ (y = 1/12) leads to the formation of a high-capacity and high-rate positive electrode material. Iron substituted materials suffer from an increased antisite defect concentration and exhibit lower capacities and poor rate capabilities. Single-phase materials are found for LiNi1/3Co1/3-yAlyMn1/3O2 when y<_ 1/4 and all exhibit decreased capacities when cycled to 4.3 V. However, an increase in rate performance and cycle stability upon aluminum substitution is correlated with an improved lamellar structure.

  11. Preparation and Electrochemical Performance of LiNi1/3Co1/3Mn1/3O2 Cathode Materials for Lithium-ion Batteries from Spent Mixed Alkaline Batteries

    NASA Astrophysics Data System (ADS)

    Yang, Li; Xi, Guoxi

    2016-01-01

    LiNi1/3Co1/3Mn1/3O2 cathode materials of lithium-ion batteries were successfully re-synthesized using mixed spent alkaline zinc-manganese batteries and spent lithium-ion batteries as the raw materials. These materials were synthesized by using a combination of dissolution, co-precipitation, calcination, battery preparation, and battery charge-discharge processes. The phase composition, morphology, and electrochemical performance of the products were determined by inductively coupled plasma optical emission spectroscopy, infrared spectra, x-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, and charge-discharge measurements. The results showed that LiNi1/3Co1/3Mn1/3O2 cathode materials could be successfully re-synthesized at optimal preparation conditions of: co-precipitation, pH value of 8, calcination temperature of 850°C, and calcination time of 10 h. Furthermore, the electrochemical results showed that the re-synthesized sample could deliver an initial discharge capacity of up to 160.2 mAh g-1 and Coulomb efficiency of 99.8%.

  12. Microstructural investigation of LixNi1/3Mn1/3Co1/3O2 (x 1) and its aged products via magnetic and diffraction study

    SciTech Connect

    Mohanty, Debasish; Gabrisch, Heike

    2012-01-01

    The thermal stability of the layered oxide LiNi1/3Mn1/3Co1/3O2 and its delithiated product is studied by a combination of x-ray and electron diffraction, TEM imaging and magnetic measurements. Diffraction shows that a small fraction of the layered material converts to spinel phase following delithiation. More spinel phase is observed after thermal annealing. The morphology of the particle changes upon thermal annealing of delithiated materials. The selected area electron diffraction and the magnetic measurement results confirm the presence of Ni+2/Li+ disorder in the delithiated material, which increases upon thermal ageing. The oxidation states of the transition metal ions were determined from magnetic data. It is shown that the charge balance due TO removal of Li+ is maintained through oxidation of Ni+2 and that the oxidation states remain stable during subsequent annealing. No anti-ferromagnetic ordering or crystallographic in plane ordering of transition metal ions is observed. These results clearly describe the thermal degradation of LixNi1/3Mn1/3Co1/3O2 (x 1) occur through the significant microstructural changes.

  13. Effects of synthesis conditions on the physical and electrochemical properties of Li1.2Mn0.54Ni0.13Co0.13O2 prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Lengyel, Miklos; Atlas, Gal; Elhassid, Dror; Luo, Peter Y.; Zhang, Xiaofeng; Belharouak, Ilias; Axelbaum, Richard L.

    2014-09-01

    Layered Li1.2Mn0.54Ni0.13Co0.13O2 materials were synthesized via spray pyrolysis. Synthesis conditions were varied in order to understand their effect on the electrochemical properties of the material. Three process parameters were evaluated: aerosol flow rate, reactor wall temperature and precursor concentration. Electrochemical results show excellent batch-to-batch reproducibility and no non-uniformities, as measured by energy dispersive X-ray spectroscopy (EDX). Phase purity is maintained for all the samples as measured by powder X-ray diffraction (XRD). The primary particle size has the most significant effect on the electrochemical performance of the materials with smaller primary particles promoting electrochemical activation and increasing capacity. Discharge capacities exceeding 200 mAh g-1 after 100 cycles at C/3 rate (where 1C = 200 mAh g-1) are consistently obtained over a wide range of operating conditions. Spray pyrolysis is shown to be a promising, robust synthesis technique for the production of Li1.2Mn0.54Ni0.13Co0.13O2 material, delivering excellent electrochemical performance within a wide range of process conditions.

  14. Li1.2Mn0.54Ni0.13Co0.13O2-Encapsulated Carbon Nanofiber Network Cathodes with Improved Stability and Rate Capability for Li-Ion Batteries.

    PubMed

    Ma, Dingtao; Zhang, Peixin; Li, Yongliang; Ren, Xiangzhong

    2015-01-01

    Li1.2Mn0.54Ni0.13Co0.13O2-encapsulated carbon nanofiber network cathode materials were synthesized by a facile electrospinning method. The microstructures, morphologies and electrochemical properties are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), galvonostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy (EIS), etc. The nanofiber decorated Li1.2Mn0.54Ni0.13Co0.13O2 electrode demonstrated higher coulombic efficiency of 83.5%, and discharge capacity of 263.7 mAh g(-1) at 1 C as well as higher stability compared to the pristine particle counterpart. The superior electrochemical performance results from the novel network structure which provides fast transport channels for electrons and lithium ions and the outer carbon acts a protection layer which prevents the inner oxides from reacting with HF in the electrolyte during charge-discharge cycling. PMID:26053003

  15. Li1.2Mn0.54Ni0.13Co0.13O2-Encapsulated Carbon Nanofiber Network Cathodes with Improved Stability and Rate Capability for Li-ion Batteries

    NASA Astrophysics Data System (ADS)

    Ma, Dingtao; Zhang, Peixin; Li, Yongliang; Ren, Xiangzhong

    2015-06-01

    Li1.2Mn0.54Ni0.13Co0.13O2-encapsulated carbon nanofiber network cathode materials were synthesized by a facile electrospinning method. The microstructures, morphologies and electrochemical properties are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), galvonostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy (EIS), etc. The nanofiber decorated Li1.2Mn0.54Ni0.13Co0.13O2 electrode demonstrated higher coulombic efficiency of 83.5%, and discharge capacity of 263.7 mAh g-1 at 1 C as well as higher stability compared to the pristine particle counterpart. The superior electrochemical performance results from the novel network structure which provides fast transport channels for electrons and lithium ions and the outer carbon acts a protection layer which prevents the inner oxides from reacting with HF in the electrolyte during charge-discharge cycling.

  16. Synthesis and electrochemical properties of lithium non-stoichiometric Li 1+ x(Ni 1/3Co 1/3Mn 1/3)O 2+ δ prepared by a spray drying method

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Min; Kumagai, Naoaki; Kadoma, Yoshihiro; Yashiro, Hitoshi

    Lithium non-stoichiometric Li[Li x(Ni 1/3Co 1/3Mn 1/3) 1- x]O 2 materials (0 ≤ x ≤ 0.17) were synthesized using a spray drying method. The electrochemical properties and structural stabilities of the synthesized materials were investigated. The synthesized materials exhibited a hexagonal structure in all the x-value and the lattice parameters of the materials were gradually decreased with increasing x-value due to an increasing amount of Ni 3+ ions for charge compensation. The capacity retention ability and rate capability of the stoichiometric Li(Ni 1/3Co 1/3Mn 1/3)O 2 material were improved by increasing x-value, the so-called overlithiation. We found that the overlithiated materials could keep more structural integrity than the stoichiometric one during electrochemical cyclings, which could be one of reasons for a better electrochemical properties of the overlithiated materials.

  17. Enhanced electrochemical performance of LiF-modified LiNi1/3Co1/3Mn1/3O2 cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Shi, S. J.; Tu, J. P.; Tang, Y. Y.; Zhang, Y. Q.; Liu, X. Y.; Wang, X. L.; Gu, C. D.

    2013-03-01

    LiF is successful used to modify the surface of layered LiNi1/3Co1/3Mn1/3O2 via a wet chemical method followed by an annealing process. The lattice structure of LiNi1/3Co1/3Mn1/3O2 is not changed distinctly after modification and part of F- dopes into the surface lattice of the oxide. The LiF-modified oxide exhibits capacity retentions of 97.5% at 0.1 C at room temperature and 93.5% at 1 C at 60 °C after 50 cycles, and delivers a high discharge capacity of 137 mAh g-1 at 10 C at room temperature. Furthermore, it has reversible capacities of 124.4 mAh g-1 at 1 C at 0 °C and 85.6 mAh g-1 at 0.1 C at -20 °C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests show that the LiF-modified layer can reduce the dissolution of metal ions in the electrode and enhance the conductivity of the oxide surface through partly F-substitution. LiF modification will be promising for the application of layered oxide for lithium ion batteries.

  18. Microstructural investigation of LixNi1/3Mn1/3Co1/3O2 (x ≤ 1) and its aged products via magnetic and diffraction study

    NASA Astrophysics Data System (ADS)

    Mohanty, D.; Gabrisch, H.

    2012-12-01

    The thermal stability of the layered oxide LiNi1/3Mn1/3Co1/3O2 and its delithiated product is studied by a combination of X-ray and electron diffraction, TEM imaging and magnetic measurements. Diffraction shows that a small fraction of the layered material converts to spinel phase following delithiation. More spinel phase is observed after thermal annealing. The morphology of the particle changes upon thermal annealing of delithiated materials. The selected area electron diffraction and the magnetic measurement results confirm the presence of Ni+2/Li+ disorder in the delithiated material, which increases upon thermal ageing. The oxidation states of the transition metal ions were determined from magnetic data. It is shown that the charge balance due to removal of Li+ is maintained through oxidation of Ni+2 and that the oxidation states remain stable during subsequent annealing. No antiferromagnetic ordering or crystallographic in plane ordering of transition metal ions is observed. These results clearly describe the thermal degradation of LixNi1/3Mn1/3Co1/3O2 (x ≤ 1) occur through the significant microstructural changes.

  19. Li1.2Mn0.54Ni0.13Co0.13O2-Encapsulated Carbon Nanofiber Network Cathodes with Improved Stability and Rate Capability for Li-ion Batteries

    PubMed Central

    Ma, Dingtao; Zhang, Peixin; Li, Yongliang; Ren, Xiangzhong

    2015-01-01

    Li1.2Mn0.54Ni0.13Co0.13O2-encapsulated carbon nanofiber network cathode materials were synthesized by a facile electrospinning method. The microstructures, morphologies and electrochemical properties are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), galvonostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy (EIS), etc. The nanofiber decorated Li1.2Mn0.54Ni0.13Co0.13O2 electrode demonstrated higher coulombic efficiency of 83.5%, and discharge capacity of 263.7 mAh g−1 at 1 C as well as higher stability compared to the pristine particle counterpart. The superior electrochemical performance results from the novel network structure which provides fast transport channels for electrons and lithium ions and the outer carbon acts a protection layer which prevents the inner oxides from reacting with HF in the electrolyte during charge-discharge cycling. PMID:26053003

  20. The probability density function in molecular gas in the G333 and Vela C molecular clouds

    NASA Astrophysics Data System (ADS)

    Cunningham, Maria

    2015-08-01

    The probability density function (PDF) is a simple analytical tool for determining the hierarchical spatial structure of molecular clouds. It has been used frequently in recent years with dust continuum emission, such as that from the Herschel space telescope and ALMA. These dust column density PDFs universally show a log-normal distribution in low column density gas, characteristic of unbound turbulent gas, and a power-law tail at high column densities, indicating the presence of gravitationally bound gas. We have recently conducted a PDF analysis of the molecular gas in the G333 and Vela C giant molecular cloud complexes, using transitions of CO, HCN, HNC, HCO+ and N2H+.The results show that CO and its isotopologues trace mostly the log-normal part of the PDF, while HCN and HCO+ trace both a log-normal part and a power law part to the distribution. On the other hand, HNC and N2H+ mostly trace only the power law tail. The difference between the PDFs of HCN and HNC is surprising, as is the similarity between HNC and the N2H+ PDFs. The most likely explanation for the similar distributions of HNC and N2H+ is that N2H+ is known to be enhanced in cool gas below 20K, where CO is depleted, while the reaction that forms HNC or HCN favours the former at similar low temperatures. The lack of evidence for a power law tail in 13CO and C18O, in conjunction for the results for the N2H+ PDF suggest that depletion of CO in the dense cores of these molecular clouds is significant. In conclusion, the PDF has proved to be a surprisingly useful tool for investigating not only the spatial distribution of molecular gas, but also the wide scale chemistry of molecular clouds.

  1. The influence of zinc hydroxystannate on reducing toxic gases (CO, NOx and HCN) generation and fire hazards of thermoplastic polyurethane composites.

    PubMed

    Wang, Bibo; Sheng, Haibo; Shi, Yongqian; Song, Lei; Zhang, Yan; Hu, Yuan; Hu, Weizhao

    2016-08-15

    A uniform zinc hydroxystannate (ZnHS) microcube was synthesized to reduce toxicity and fire hazards of thermoplastic polyurethane (TPU) composites using ammonium polyphosphate as a flame retardant agent. The structure, morphology and thermal properties of ZnHS were characterized by X-ray diffraction, transmission electron microscopy and thermogravimetric analysis, respectively. Smoke suppression properties and synergistic flame retardant effect of ZnHS on flame retardant TPU composites were intensively investigated by smoke density test, cone calorimeter test, and thermalgravimetric analysis. Thermogravimetric analysis/infrared spectrometry and tube furnace were employed to evaluate the toxic gases (CO, NOx and HCN) of TPU composites. The incorporation of ZnHS into TPU matrix effectively improved the fire safety and restrained the smoke density, which is attributed to that the char residue catalyzed by ZnHS enhanced barrier effect that reduced peak heat release rate, total heat release, smoke particles and organic volatiles during combustion. Furthermore, the ZnHS synergist demonstrated high efficiency in catalytic degradation of the toxic gases, which obviously decreased total volatiled product and toxic volatiles evolved, such as the CO, HCN and NOx, indicating suppressed toxicity of the TPU composites. PMID:27136731

  2. Possible selective formation of CNC/sup +/ and CCN/sup +/ in the interstellar reactions of C/sup +/ with HCN and HNC/sup +/

    SciTech Connect

    Haese, N.N.; Woods, R.C.

    1981-05-15

    The molecular structures of CNC/sup +/ and CCN/sup +/ have been determined by double zeta self-consistent field (SCF) calculations. Their standard heats of formation are theoretically estimated to be 372 +- 20 and 421 +- 25 kcal mol/sup -1/, respectively, the latter determined by double zeta plus polarization SCF-CI (configuration interaction) calculation of the isomerization energy for CNC/sup +/..-->..CCN/sup +/. Using these results, the available appearance potential data for these ions in the mass spectra of HC/sub 3/N and C/sub 2/N/sub 2/ can be explained by simple reactions, and the numerical agreement between the corresponding experimental and theoretical heats of formation is excellent. With this thermochemical information and mechanistic considerations of C/sup +/ reactions with HCN and HNC, we propose that CNC/sup +/ may be selectively made from HCN, and CCN/sup +/ from HNC, and that this selectivity may play an important role in the chemistry of the interstellar medium. For the polar isomer CCN/sup +/ we report an SCF prediction of its rotational constant (11.93 +- 0.5 GHz) and a higher-level (CI) calculation of its electric dipole moment (2.50 +- 0.2 debye) and nitrogen nuclear quadrupole coupling constant (-4.95 +- 0.5 MHz).

  3. A new ab initio potential energy surface for the collisional excitation of HCN by para- and ortho-H{sub 2}

    SciTech Connect

    Denis-Alpizar, Otoniel; Kalugina, Yulia; Stoecklin, Thierry; Vera, Mario Hernández; Lique, François

    2013-12-14

    We present a new four-dimensional potential energy surface for the collisional excitation of HCN by H{sub 2}. Ab initio calculations of the HCN–H{sub 2} van der Waals complex, considering both molecules as rigid rotors, were carried out at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12a] level of theory using an augmented correlation-consistent triple zeta (aVTZ) basis set. The equilibrium structure is linear HCN–H{sub 2} with the nitrogen pointing towards H{sub 2} at an intermolecular separation of 7.20 a{sub 0}. The corresponding well depth is −195.20 cm{sup −1}. A secondary minimum of −183.59 cm{sup −1} was found for a T-shape configuration with the H of HCN pointing to the center of mass of H{sub 2}. We also determine the rovibrational energy levels of the HCN–para-H{sub 2} and HCN–ortho-H{sub 2} complexes. The calculated dissociation energies for the para and ortho complexes are 37.79 cm{sup −1} and 60.26 cm{sup −1}, respectively. The calculated ro-vibrational transitions in the HCN–H{sub 2} complex are found to agree by more than 0.5% with the available experimental data, confirming the accuracy of the potential energy surface.

  4. GAS EMISSIONS IN PLANCK COLD DUST CLUMPS-A SURVEY OF THE J = 1-0 TRANSITIONS OF {sup 12}CO, {sup 13}CO, AND C{sup 18}O

    SciTech Connect

    Wu Yuefang; Liu Tie; Meng, Fanyi; Li Di; Qin Shengli; Ju Binggang

    2012-09-01

    A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J = 1-0 transitions of {sup 12}CO, {sup 13}CO, and C{sup 18}O has been carried out using the Purple Mountain Observatory 13.7 m telescope. Six hundred seventy-three clumps were detected with {sup 12}CO and {sup 13}CO emission, and 68% of the sample has C{sup 18}O emission. Additional velocity components were also identified. A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given for all the velocity components, and half of the clumps are located within 0.5 and 1.5 kpc. Excitation temperatures range from 4 to 27 K, slightly larger than those of T{sub d} . Line width analysis shows that the majority of ECC clumps are low-mass clumps. Column densities N{sub H{sub 2}} span from 10{sup 20} to 4.5 Multiplication-Sign 10{sup 22} cm{sup -2} with an average value of (4.4 {+-} 3.6) Multiplication-Sign 10{sup 21} cm{sup -2}. N{sub H{sub 2}} cumulative fraction distribution deviates from the lognormal distribution, which is attributed to optical depth. The average abundance ratio of the {sup 13}CO to C{sup 18}O in these clumps is 7.0 {+-} 3.8, higher than the terrestrial value. Dust and gas are well coupled in 95% of the clumps. Blue profile asymmetry, red profile asymmetry, and total line asymmetry were found in less than 10% of the clumps, generally indicating that star formation is not yet developed. Ten clumps were mapped. Twelve velocity components and 22 cores were obtained. Their morphologies include extended diffuse, dense, isolated, cometary, and filament, of which the last is the majority. Twenty cores are starless, and only seven cores seem to be in a gravitationally bound state. Planck cold clumps are the most quiescent among the samples of weak red IRAS, infrared dark clouds, UC H II candidates, extended green objects, and methanol maser sources, suggesting that Planck cold clumps have expanded the horizon of cold

  5. ASTE observations in the 345 GHz window towards the HII region N113 of the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Paron, S.; Ortega, M. E.; Cunningham, M.; Jones, P. A.; Rubio, M.; Fariña, C.; Komugi, S.

    2014-12-01

    Aims: The HII region N113 is located in the central part of the Large Magellanic Cloud (LMC) with an associated molecular cloud that is very rich in molecular species. Most of the previously observed molecular lines cover the frequency range 85-270 GHz. Thus, a survey and study of lines at the 345 GHz window is required for a more complete understanding of the chemistry and excitation conditions of this region. Methods: We mapped a region of 2.´5 × 2.´5 centred at N113 using the Atacama Submillimeter Telescope Experiment in the 13CO J = 3-2 line with an angular and spectral resolution of 22'' and 0.11 km s-1. In addition, we observed 16 molecular lines as single pointings towards its centre. Results: From the 13CO J = 3-2 map we estimate the local thermodynamic equilibrium (LTE) and virial masses in about 1 × 104 and 4.5 × 104M⊙ for the molecular cloud associated with N113. From the dust continuum emission at 500 μm we additionally obtain a mass of gas of 7 × 103M⊙. Towards the cloud centre we detected emission from 12CO, 13CO, C18O (3-2), HCN, HNC, HCO+, C2H (4-3), and CS (7-6); these are the first reported detections of the HCN, HNC, and C2H (4-3) lines from this region. We confirm the detection of CS (7-6), which was previously tentatively detected. From analysing the HCN, HNC, and C2H lines we suggest that they might be emitted from a photodissociation region (PDR). Moreover, we suggest that the chemistry involving the C2H lines in N113 is probably similar to that in Galactic PDRs. We analysed the HCN J = 4-3, J = 3-2, and J = 1-0 lines with the code RADEX and we conclude that we observe very high density gas, between some 105 and 107 cm-3.

  6. Physical properties of Planck Cold Dust Clumps

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Liu, T.; Meng, F.; Yuan, J.; Zhang, T.; Chen, P.; Hu, R.; Li, D.; Qin, S.; Ju, B.

    2016-05-01

    To explore physical properties of Planck cold dust clumps, 674 of the pilot samples were observed at the 13.7 m telescope of Purple Mountain Observatory (PMO) in J = 1 - 0 transitions of CO, 13CO and C18O. HCO+, HCN and N2H+ emissions were also observed with PMO 13.7 m and IRAM 30 m telescopes. They are real cold and quiescent with mean Tk ˜ 10 K and mean FWHM of 13CO (1-0) 1.27 km s-1. Column density ranges from 1020 to 1022 cm-2. Gas of the Planck clumps extends molecular space in the Milky Way. Turbulence dominates in cores. Filament structure is the majority and most of the cores are starless. Ten percent of the cores show asymmetric emission features including blue- and red- profiles. Planck clumps include different cold or low luminosity sources. Dense cores constitute an ideal sample for studying initial state of star formation while the diffuse clumps are suitable for investigating the formation of cores.

  7. Molecular gas of Planck cold dust clumps

    NASA Astrophysics Data System (ADS)

    Wu, Yuefang

    2015-08-01

    To probe dynamical processes and physical properties of Planck Cold Clumps, survey and mapping of 674 most reliable Planck cold dust clumps with J=1-0 of CO,13CO and C18O were made at PMO 13.7 m telescope. More than 600 molecular cores were obtained, which are mainly located in seven molecular complexes divided by Dame (1987). Parameters of cores in different regions are with some difference, showing different evolutional status and environment of the cores. As a whole they are quiescent. Some are with star forming activities. J=1-0 lines of HCO+ and HCN at CO emission peaks were also observed at PMO, of which 24 were mapped with IRAM 30 m telescope. Several cores were also observed with J=2-1 of CO and 13CO using CSO. Core splits were detected. Combining with infrared data more than 70% of CO cores are identified as starless. Planck cold clumps seem to be ideal samples to search for candidates of massive prestellar cores and pre-clusters.

  8. Mesoporous Li1.2Mn0.54Ni0.13Co0.13O2 nanotubes for high-performance cathodes in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Ma, Dingtao; Li, Yongliang; Zhang, Peixin; Cooper, Adam J.; Abdelkader, Amr M.; Ren, Xiangzhong; Deng, Libo

    2016-04-01

    One-dimensional nanotubes constructed from interconnected Li1.2Mn0.54Ni0.13Co0.13O2 secondary particles of diameters measuring ca. 40 nm, were synthesized by a one-pot electrospinning method. Novel electrodes were constructed from (a) nanoparticles only, and (b) hollow nanofibres, and employed as cathodes in Li-ion batteries. The nanotube cathode exhibited impressive specific charge capacity, good cycling stability, and excellent rate capability. A discharge capacity of 140 mAh g-1 with capacity retention of 89% at 3 C was achieved after 300 cycles. The significant improvement of electrochemical performance is attributed to the high surface area of the nanotubes, well-guided charge transfer kinetics with short ionic diffusion pathways, and large effective contact area with the electrolyte during the cycling process.

  9. Ab initio wavenumber accurate spectroscopy : {sup 1}CH{sub 2} and HCN vibrational levels on automatically generated IMLS potential energy surfaces.

    SciTech Connect

    Dawes, R.; Wagner, A. F.; Thompson, D. L.; Chemical Sciences and Engineering Division; Univ. of Missouri at Columbia

    2009-04-23

    We report here calculated J = 0 vibrational frequencies for {sup 1}CH{sub 2} and HCN with root-mean-square error relative to available measurements of 2.0 cm{sup -1} and 3.2 cm{sup -1}, respectively. These results are obtained with DVR calculations with a dense grid on ab initio potential energy surfaces (PESs). The ab initio electronic structure calculations employed are Davidson-corrected MRCI calculations with double-, triple-, and quadruple-{zeta} basis sets extrapolated to the complete basis set (CBS) limit. In the {sup 1}CH{sub 2} case, Full CI tests of the Davidson correction at small basis set levels lead to a scaling of the correction with the bend angle that can be profitably applied at the CBS limit. Core-valence corrections are added derived from CCSD(T) calculations with and without frozen cores. Relativistic and non-Born-Oppenheimer corrections are available for HCN and were applied. CBS limit CCSD(T) and CASPT2 calculations with the same basis sets were also tried for HCN. The CCSD(T) results are noticeably less accurate than the MRCI results while the CASPT2 results are much poorer. The PESs were generated automatically using the local interpolative moving least-squares method (L-IMLS). A general triatomic code is described where the L-IMLS method is interfaced with several common electronic structure packages. All PESs were computed with this code running in parallel on eight processors. The L-IMLS method provides global and local fitting error measures important in automatically growing the PES from initial ab initio seed points. The reliability of this approach was tested for {sup 1}CH{sub 2} by comparing DVR-calculated vibrational levels on an L-IMLS ab initio surface with levels generated by an explicit ab initio calculation at each DVR grid point. For all levels ({approx}200) below 20000 cm{sup -1}, the mean unsigned difference between the levels of these two calculations was 0.1 cm{sup -1}, consistent with the L-IMLS estimated mean unsigned

  10. 1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether as a co-solvent for high voltage LiNi1/3Co1/3Mn1/3O2/graphite cells

    NASA Astrophysics Data System (ADS)

    Wang, Chengyun; Zuo, Xiaoxi; Zhao, Minkai; Xiao, Xin; Yu, Le; Nan, Junmin

    2016-03-01

    1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether (F-EAE) mixed with ethylene carbonate (EC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF6) is evaluated as a co-solvent high-potential electrolyte of LiNi1/3Co1/3Mn1/3O2/graphite batteries. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicate that the EC/DEC-based electrolyte with F-EAE possesses a high oxidation potential (>5.2 V vs. Li/Li+) and excellent film-forming characteristics. With 40 wt% F-EAE in the electrolyte, the capacity retention of the LiNi1/3Co1/3Mn1/3O2/graphite pouch cells that are cycled between 3.0 and 4.5 V is significantly improved from 28.8% to 86.8% after 100 cycles. In addition, electrochemical impedance spectroscopy (EIS) of three-electrode pouch cells, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) are used to characterize the effects of F-EAE on the enhanced capacity retention. It is demonstrated that F-EAE facilitates the formation of a stable surface electrolyte interface (SEI) layer with low impedance on the anode and effectively suppresses an increase in the charge-transfer resistance on the cathode. These results suggest that F-EAE can serve as an alternative electrolyte solvent for 4.5 V high voltage rechargeable lithium-ion batteries.

  11. Solid-State Nuclear Magnetic Resonance Measurements of HIV Fusion Peptide 13CO to Lipid 31P Proximities Support Similar Partially Inserted Membrane Locations of the α Helical and β Sheet Peptide Structures

    NASA Astrophysics Data System (ADS)

    Gabrys, Charles M.; Qiang, Wei; Sun, Yan; Xie, Li; Schmick, Scott D.; Weliky, David P.

    2013-10-01

    Fusion of the human immunodeficiency virus (HIV) membrane and the host cell membrane is an initial step of infection of the host cell. Fusion is catalyzed by gp41, which is an integral membrane protein of HIV. The fusion peptide (FP) is the -25 N-terminal residues of gp41 and is a domain of gp41 that plays a key role in fusion catalysis likely through interaction with the host cell membrane. Much of our understanding of the FP domain has been accomplished with studies of -HFP-, i.e., a -25-residue peptide composed of the FP sequence but lacking the rest of gp41. HFP catalyzes fusion between membrane vesicles and serves as a model system to understand fusion catalysis. HFP binds to membranes and the membrane location of HFP is likely a significant determinant of fusion catalysis perhaps because the consequent membrane perturbation reduces the fusion activation energy. In the present study, many HFPs were synthesized and differed in the residue position that was 13CO backbone labeled. Samples were then prepared that each contained a singly 13CO labeled HFP incorporated into membranes that lacked cholesterol. HFP had distinct molecular populations with either α helical or oligomeric - sheet structure. Proximity between the HFP 13CO nuclei and 31P nuclei in the membrane headgroups was probed by solid-state NMR (SSNMR) rotational-echo double-resonance (REDOR) measurements. For many samples, there were distinct 13CO shifts for the α helical and - sheet structures so that the proximities to 31P nuclei could be determined for each structure. Data from several differently labeled HFPs were then incorporated into a membrane location model for the particular structure. In addition to the 13CO labeled residue position, the HFPs also differed in sequence and/or chemical structure. -HFPmn- was a linear peptide that contained the 23 N-terminal residues of gp41. -HFPmn_V2E- contained the V2E mutation that for HIV leads to greatly reduced extent of fusion and infection. The

  12. The structure and kinematics of dense gas in NGC 2068

    NASA Astrophysics Data System (ADS)

    Walker-Smith, S. L.; Richer, J. S.; Buckle, J. V.; Smith, R. J.; Greaves, J. S.; Bonnell, I. A.

    2013-03-01

    We have carried out a survey of the NGC 2068 region in the Orion B molecular cloud using HARP on the James Clerk Maxwell Telescope, in the 13CO and C18O (J = 3-2) and H13CO+ (J = 4-3) lines. We used 13CO to map the outflows in the region, and matched them with previously defined Submillimetre Common-User Bolometer Array cores. We decomposed the C18O and H13CO+ into Gaussian clumps, finding 26 and eight clumps, respectively. The average deconvolved radii of these clumps are 6200 ± 2000 and 3600 ± 900 au for C18O and H13CO+, respectively. We have also calculated virial and gas masses for these clumps, and hence determined how bound they are. We find that the C18O clumps are more bound than the H13CO+ clumps (average gas mass to virial mass ratio of 4.9 compared to 1.4). We measure clump internal velocity dispersions of 0.28 ± 0.02 and 0.27 ± 0.04 km s-1 for C18O and H13CO+, respectively, although the H13CO+ values are heavily weighted by a majority of the clumps being protostellar, and hence having intrinsically greater linewidths. We suggest that the starless clumps correspond to local turbulence minima, and we find that our clumps are consistent with formation by gravoturbulent fragmentation. We also calculate interclump velocity dispersions of 0.39 ± 0.05 and 0.28 ± 0.08 km s-1 for C18O and H13CO+, respectively. The velocity dispersions (both internal and external) for our clumps match results from numerical simulations of decaying turbulence in a molecular cloud. However, there is still insufficient evidence to conclusively determine the type of turbulence and time-scale of star formation, due to the small size of our sample.

  13. Adsorption sensitivity of zigzag GeC nanotube towards N2, CO, SO2, HCN, NH3, and H2CO molecules

    NASA Astrophysics Data System (ADS)

    Samanta, Pabitra Narayan; Das, Kalyan Kumar

    2013-07-01

    Reactivities of the single-walled (6,0) germanium carbide nanotube (GeCNT) towards the small molecules like N2, CO, SO2, HCN, NH3, and H2CO are theoretically studied at the ONIOM(B3LYP/LANL2DZ/6-311++G(d,p):UFF) level. For the adsorption of a single molecule, a pyrene-like ring of the nanotube is chosen as the adsorption site in the high layer of the ONIOM calculations, while a coronene-like ring is considered for the adsorption of the second molecule. The nature of the binding between the nanotube and the adsorbate molecule is analyzed from the computed binding energy, density of states (DOS), charge transfer, and isosurface of total electron density.

  14. Warm and Dense Molecular Gas in the N 159 Region: 12CO J = 4-3 and 13CO J = 3-2 Observations with NANTEN2 and ASTE

    NASA Astrophysics Data System (ADS)

    Mizuno, Yoji; Kawamura, Akiko; Onishi, Toshikazu; Minamidani, Tetsuhiro; Muller, Erik; Yamamoto, Hiroaki; Hayakawa, Takahiro; Mizuno, Norikazu; Mizuno, Akira; Stutzki, Jürgen; Pineda, Jorge L.; Klein, Uli; Bertoldi, Frank; Koo, Bon-Chul; Rubio, Monica; Burton, Michael; Benz, Arnold; Ezawa, Hajime; Yamaguchi, Nobuyuki; Kohno, Kotaro; Hasegawa, Tetsuo; Tatematsu, Ken'ichi; Ikeda, Masafumi; Ott, Jürgen; Wong, Tony; Hughes, Annie; Meixner, Margaret; Indebetouw, Remy; Gordon, Karl D.; Whitney, Barbara; Bernard, Jean-Philippe; Fukui, Yasuo

    2010-02-01

    New 12CO J = 4-3 and 13CO J = 3-2 observations of the N 159 region, an active site of massive star formation in the Large Magellanic Cloud, have been made with the NANTEN2 and ASTE submillimeter telescopes, respectively. The 12CO J = 4-3 distribution is separated into three clumps, each associated with N 159 W, N 159 E, and N 159 S. These new measurements toward the three clumps are used in coupled calculations of molecular rotational excitation and line radiation transfer, along with other transitions of the 12CO J = 1-0, J = 2-1, J = 3-2, and J = 7-6 as well as the isotope transitions of 13CO J = 1-0, J = 2-1, J = 3-2, and J = 4-3. The 13CO J = 3-2 data were newly taken for the present work. The temperatures and densities were found to be ˜70-80 K and ˜3 × 10³ cm-3 in N 159 W and N 159 E, and ˜30 K and ˜1.6 × 10³ cm-3 in N 159 S. These results were compared with the star-formation activity based on data of young stellar clusters and HII regions as well as midinfrared emission obtained with the Spitzer MIPS. The N 159 E clump is associated with cluster(s) embedded, as observed at 24μm by the Spitzer MIPS, and the derived high temperature, 80 K, is interpreted as being heated by these sources. The N 159 E clump is likely to be responsible for a dark lane in a large HII region by dust extinction. On the other hand, the N 159 W clump is associated with clusters embedded mainly toward the eastern edge of the clump only. These clusters show offsets of 20''-40'' from the 12CO J = 4-3 peak, and are probably responsible for heating indicated by the derived high temperature, 70 K. The N 159 W clump exhibits no sign of star formation toward the 12CO J = 4-3 peak position and its western region that shows enhanced R4-3/1-0 and R3-2/1-0 ratios. We therefore suggest that the N 159 W peak represents a pre-star-cluster core of ˜105Modot which deserves further detailed studies. The N 159 S clump shows little sign of star formation, as is consistent with the lower

  15. Underlying mechanisms of the synergistic role of Li2MnO3 and LiNi1/3Co1/3Mn1/3O2 in high-Mn, Li-rich oxides.

    PubMed

    Lim, Jin-Myoung; Kim, Duho; Park, Min-Sik; Cho, Maenghyo; Cho, Kyeongjae

    2016-04-28

    For large-scale energy storage applications requiring high energy density, the development of Li-rich oxides with enhanced cyclic stabilities during high-voltage operations and large specific capacities is required. In this regard, high-Mn, Li-rich oxides (HMLOs; xLi2MnO3 (1 - x)LiNi1/3Co1/3Mn1/3O2 at x > 0.5) warrant an in-depth study because of their good cyclic performance at high operating voltages and potentially large specific capacities. Here, to understand the synergistic effects and enhanced cyclic stability of HMLOs, mechanically blended HMLO (m-HMLO) and chemically bonded HMLO (c-HMLO) were prepared and investigated. c-HMLO exhibits relatively high reaction voltages, large specific capacities, and enhanced cyclic stabilities (∼99%) at a high operating voltage (∼4.8 V vs. Li/Li(+)) compared with m-HMLO. First-principles calculations with electronic structure analysis were performed using an atomic model developed by Rietveld refinement using as-synthesised c-HMLO. The redox mechanisms of Ni, Co, and Mn ions were determined via the partial density of states of the ground states predicted using the cluster expansion method, which elucidates that LiNi1/3Co1/3Mn1/3O2 stabilises the transition metal (TM) layer of Li2MnO3 and separates Li delithiation potentials in Li2MnO3 in the HMLO. Kinetic analyses including electronic structures revealed that the interlayer migration of TMs from the TM layer to the Li layer depends on the crystal field stabilisation. Thus, TMs with reduced character in the tetrahedral sites than the octahedral sites owing to the effects of crystal field stabilisation, such as Ni ions, in HMLOs would face a higher interlayer migration barrier, impeding phase transformation into spinel phases. Furthermore, Cu ions could constitute a doping source for HMLOs to improve the material's cyclic stability through this mechanism. These characteristics may be widely applied to explain experimental phenomena and improve the properties of cathode materials for Li-ion batteries. PMID:27056677

  16. Using eddy covariance of CO2, 13CO2 and CH4, continuous soil respiration measurements, and PhenoCams to constrain a process-based biogeochemical model for carbon market-funded wetland restoration

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Baldocchi, D. D.; Knox, S. H.; Sturtevant, C. S.; Verfaillie, J. G.; Dronova, I.; Jenerette, D.; Poindexter, C.; Huang, Y. W.

    2015-12-01

    We use multiple data streams in a model-data fusion approach to reduce uncertainty in predicting CO2 and CH4 exchange in drained and flooded peatlands. Drained peatlands in the Sacramento-San Joaquin River Delta, California are a strong source of CO2 to the atmosphere and flooded peatlands or wetlands are a strong CO2 sink. However, wetlands are also large sources of CH4 that can offset the greenhouse gas mitigation potential of wetland restoration. Reducing uncertainty in model predictions of annual CO2 and CH4 budgets is critical for including wetland restoration in Cap-and-Trade programs. We have developed and parameterized the Peatland Ecosystem Photosynthesis, Respiration, and Methane Transport model (PEPRMT) in a drained agricultural peatland and a restored wetland. Both ecosystem respiration (Reco) and CH4 production are a function of 2 soil carbon (C) pools (i.e. recently-fixed C and soil organic C), temperature, and water table height. Photosynthesis is predicted using a light use efficiency model. To estimate parameters we use a Markov Chain Monte Carlo approach with an adaptive Metropolis-Hastings algorithm. Multiple data streams are used to constrain model parameters including eddy covariance of CO2, 13CO2 and CH4, continuous soil respiration measurements and digital photography. Digital photography is used to estimate leaf area index, an important input variable for the photosynthesis model. Soil respiration and 13CO2 fluxes allow partitioning of eddy covariance data between Reco and photosynthesis. Partitioned fluxes of CO2 with associated uncertainty are used to parametrize the Reco and photosynthesis models within PEPRMT. Overall, PEPRMT model performance is high. For example, we observe high data-model agreement between modeled and observed partitioned Reco (r2 = 0.68; slope = 1; RMSE = 0.59 g C-CO2 m-2 d-1). Model validation demonstrated the model's ability to accurately predict annual budgets of CO2 and CH4 in a wetland system (within 14% and 1

  17. Static and Dynamic Studies on LiNi1/3 Co1/3 Mn1/3 O2 -Based Suspensions for Semi-Solid Flow Batteries.

    PubMed

    Biendicho, Jordi Jacas; Flox, Cristina; Sanz, Laura; Morante, Joan Ramon

    2016-08-01

    LiNi1/3 Co1/3 Mn1/3 O2 (LNCM)-based suspensions for semi-solid flow batteries (SSFB) have been investigated by galvanostatic charge/discharge an electrochemical impedance spectroscopy (EIS). The resistance and electrochemical performance of half cells (vs. Li/Li(+) ) as well as the rheological properties are affected by the content of a commercially available electroconductive carbon black [KetjenBlack (KB), AkzoNobel] in the suspensions. In static conditions, a cell with 11.87 and 13.97 % by volume of KB and LNCM delivers high capacity 130 mA h g(-1) at 5 mA cm(-2) , respectively, and a coulombic efficiency of 90 % over 10 injections. The impedance of half cells is dominated by a contact resistance fitted with a resistor and a constant phase element (CPE) in parallel. In flow conditions, cell potential depends on applied current density and measured over potentials are ∼0.3 and 0.7 V for 0.33 and 1 mA cm(-2) , respectively, for a cell containing a suspension with 9.53 % in volume of KB and 13.90 % in volume of LNCM. The effect of the cell contact resistance on the electrochemical performance is discussed. PMID:27332781

  18. The effect of different binders on electrochemical properties of LiNi1/3Mn1/3Co1/3O2 cathode material in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Xu, Jiantie; Chou, Shu-Lei; Gu, Qin-fen; Liu, Hua-Kun; Dou, Shi-Xue

    2013-03-01

    LiNi1/3Mn1/3Co1/3O2 (NMC) as a cathode material for lithium ion batteries has been synthesized by the sol-gel method. The X-ray diffraction Rietveld refinement results indicated that single-phase NMC with hexagonal layered structure was obtained. Scanning electron microscope images revealed well crystallized NMC with uniform particle size in the range of 100-200 nm. The performance of the NMC electrodes with sodium carboxylmethyl cellulose (CMC), poly(vinylidene fluoride) (PVDF), and alginate from brown algae as binders was compared. Constant current charge-discharge test results demonstrated that the NMC electrode using CMC as binder had the highest rate capability, followed by those using alginate and PVDF binders, respectively. Electrochemical impedance spectroscopy test results showed that the electrode using CMC as the binder had lower charge transfer resistance and lower apparent activation energy than the electrodes using alginate and PVDF as the binders. The apparent activation energies of NMC electrodes using CMC, alginate, and PVDF as binders were calculated to be 27.4 kJ mol-1, 33.7 kJ mol-1, and 36 kJ mol-1, respectively.

  19. Countering the Segregation of Transition-Metal Ions in LiMn1/3 Co1/3 Ni1/3 O2 Cathode for Ultralong Life and High-Energy Li-Ion Batteries.

    PubMed

    Luo, Dong; Fang, Shaohua; Tamiya, Yu; Yang, Li; Hirano, Shin-Ichi

    2016-08-01

    High-voltage layered lithium transition-metal oxides are very promising cathodes for high-energy Li-ion batteries. However, these materials often suffer from a fast degradation of cycling stability due to structural evolutions. It seriously impedes the large-scale application of layered lithium transition-metal oxides. In this work, an ultralong life LiMn1/3 Co1/3 Ni1/3 O2 microspherical cathode is prepared by constructing an Mn-rich surface. Its capacity retention ratio at 700 mA g(-1) is as large as 92.9% after 600 cycles. The energy dispersive X-ray maps of electrodes after numerous cycles demonstrate that the ultralong life of the as-prepared cathode is attributed to the mitigation of TM-ions segregation. Additionally, it is discovered that layered lithium transition-metal oxide cathodes with an Mn-rich surface can mitigate the segregation of TM ions and the corrosion of active materials. This study provides a new strategy to counter the segregation of TM ions in layered lithium transition-metal oxides and will help to the design and development of high-energy cathodes with ultralong life. PMID:27389965

  20. Li-ion storage performance and electrochemically induced phase evolution of layer-structured Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhang, Hong; Ma, Zhiyuan; Wang, Gaomin; Li, Zhicheng

    2016-06-01

    Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (LMNC) powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characterized. The 900°C calcined powders have a hexagonal layered structure with high ordered degree and low cationic mixing level. The calcined materials as cathode electrode for Li-ion battery deliver the high electrochemical properties with an initial discharge capacity of 243.5 mA•h•g-1 at 25 mA•g-1 and 249.2 mA•h•g-1 even after 50 cycles. The electrochemically induced phase evolution investigated by a transmission electron microscopy indicates that Li+ ions deintercalated first from the LiMO2 (M = Mn, Co, Ni) component and then from Li2MnO3 component in the LMNC during the charge process, while Li+ ions intercalated into Li1-xMO2 component followed by into MnO2 component during the discharge process.

  1. The impact of calendar aging on the thermal stability of a LiMn2O4-Li(Ni1/3Mn1/3Co1/3)O2/graphite lithium-ion cell

    NASA Astrophysics Data System (ADS)

    Röder, Patrick; Stiaszny, Barbara; Ziegler, Jörg C.; Baba, Nilüfer; Lagaly, Paul; Wiemhöfer, Hans-Dieter

    2014-12-01

    Aging of lithium-ion cells is an inevitable phenomenon limiting the lifetime. Undesirable side reactions during cycle or calendar aging may affect the performance of all components of the lithium-ion cell. This results in a decreased capacity and an increase in the overall cell impedance. Based on electrochemical and physical characterization methods, the aging behavior during calendar aging of a 18650-cell, containing a blend of LiMn2O4 and Li(Ni1/3Mn1/3Co1/3)O2 (NMC) as cathode material and graphite as anode material was systematically investigated. To understand how the safety behavior of a lithium-ion cell changes with aging, accelerating rate calorimetry (ARC) and differential scanning calorimetry (DSC) were applied. With these methods the thermal stability behavior of the complete lithium-ion cell and its respective cathode and anode material were investigated. The focus of this work was it to generate first cause-effect relations between the aging under one exemplary aging condition and the thermal stability of a lithium-ion battery both on cell and material level.

  2. Preparation of thick-film LiNi1/3Co1/3Mn1/3O2 electrodes by aerosol deposition and its application to all-solid-state batteries

    NASA Astrophysics Data System (ADS)

    Iwasaki, Shinya; Hamanaka, Tadashi; Yamakawa, Tomohiro; West, William C.; Yamamoto, Kazuo; Motoyama, Munekazu; Hirayama, Tsukasa; Iriyama, Yasutoshi

    2014-12-01

    We prepared thick and dense-crystalline LiNi1/3Co1/3Mn1/3O2 (NMC) composite films at room temperature that can work well as cathodes in all-solid-state battery cells. The thick films were fabricated by aerosol deposition using NMC powder (D50 = 10.61 μm) as a source material. Commercially-obtained NMC powder did not form films at all on silicon wafer substrates, and cracking of the substrates was observed. However, a few tens of nanometer coating with amorphous niobium oxide resulted in the deposition of 7 μm-thick crystalline dense composite films. The films were successfully fabricated also on Li+-conductive glass-ceramic sheets with 150 μm in thickness, and all-solid-state batteries were fabricated. The solid-state battery provided a cathode-basis discharge capacity of 152 mAh g-1 (3.0-4.2 V, 0.025 C, 333 K) and repeated charge-discharge cycles for 20 cycles.

  3. Li-ion storage performance and electrochemically induced phase evolution of layer-structured Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhang, Hong; Ma, Zhiyuan; Wang, Gaomin; Li, Zhicheng

    2016-04-01

    Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (LMNC) powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characterized. The 900°C calcined powders have a hexagonal layered structure with high ordered degree and low cationic mixing level. The calcined materials as cathode electrode for Li-ion battery deliver the high electrochemical properties with an initial discharge capacity of 243.5 mA•h•g-1 at 25 mA•g-1 and 249.2 mA•h•g-1 even after 50 cycles. The electrochemically induced phase evolution investigated by a transmission electron microscopy indicates that Li+ ions deintercalated first from the LiMO2 (M = Mn, Co, Ni) component and then from Li2MnO3 component in the LMNC during the charge process, while Li+ ions intercalated into Li1-x MO2 component followed by into MnO2 component during the discharge process.

  4. A study of interface-sustained ferromagnetism in 1/2(1-x)Ln2O3-xSrO/1/3Co3O4 nano-composite.

    PubMed

    Tay, Siok Wei; Hong, Liang; Liu, Zhaolin

    2007-02-15

    The binary oxide composite, consisting of rock salt-type SrO and spinel Co3O4 nano-domains, exhibits soft ferromagnetic properties at ambient temperature. This ferromagnetism is originated from interface-induction, and the magnitude of the magnetic properties can be enhanced when the spinel phase of the composite is doped by a small amount of Ln2O3 (Ln = La, Nd, for instance). In this work, we study the composites of tri-oxide, 1/2(1-x)Ln2O3-xSrO/1/3Co3O4, where 0.01 < or =1-x < or = 0.6, by focusing on three areas: (i) generation of nano-composite dominant by interfacial phase via the pyrolysis of preceramic metallo-organic gel; (ii) influence of post-pyrolysis calcination and Ln2O3 content on the phase composition of the composite; and (iii) elucidation of different magnetic responses caused by the nature of Ln2O3 dissolved in the Co3O4 phase. The Ln(3+)-doped Co3O4 oxide displays only paramagnetic behavior at room temperature, but the ferromagnetic response is attained upon its mixing with SrO in nano-scale. The SrO phase plays the role in assisting Co3O4 phase with aligning unpaired electrons through interfacial induction. PMID:17126355

  5. Boreal forest fire emissions in fresh Canadian smoke plumes: C1-C10 volatile organic compounds (VOCs), CO2, CO, NO2, NO, HCN and CH3CN

    NASA Astrophysics Data System (ADS)

    Simpson, I. J.; Akagi, S. K.; Barletta, B.; Blake, N. J.; Choi, Y.; Diskin, G. S.; Fried, A.; Fuelberg, H. E.; Meinardi, S.; Rowland, F. S.; Vay, S. A.; Weinheimer, A. J.; Wennberg, P. O.; Wiebring, P.; Wisthaler, A.; Yang, M.; Yokelson, R. J.; Blake, D. R.

    2011-07-01

    Boreal regions comprise about 17 % of the global land area, and they both affect and are influenced by climate change. To better understand boreal forest fire emissions and plume evolution, 947 whole air samples were collected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous measurements of CO2, CO, CH4, CH2O, NO2, NO, HCN and CH3CN, these measurements represent the most comprehensive assessment of trace gas emissions from boreal forest fires to date. Based on 105 air samples collected in fresh Canadian smoke plumes, 57 of the 80 measured NMVOCs (including CH2O) were emitted from the fires, including 45 species that were quantified from boreal forest fires for the first time. After CO2, CO and CH4, the largest emission factors (EFs) for individual species were formaldehyde (2.1 ± 0.2 g kg-1), followed by methanol, NO2, HCN, ethene, α-pinene, β-pinene, ethane, benzene, propene, acetone and CH3CN. Globally, we estimate that boreal forest fires release 2.4 ± 0.6 Tg C yr-1 in the form of NMVOCs, with approximately 41 % of the carbon released as C1-C2 NMVOCs and 21 % as pinenes. These are the first reported field measurements of monoterpene emissions from boreal forest fires, and we speculate that the pinenes, which are relatively heavy molecules, were detected in the fire plumes as the result of distillation of stored terpenes as the vegetation is heated. Their inclusion in smoke chemistry models is expected to improve model predictions of secondary organic aerosol (SOA) formation. The fire-averaged EF of dichloromethane or CH2Cl2, (6.9 ± 8.6) × 10-4 g kg-1, was not significantly different from zero and supports recent findings that its global biomass burning source appears to have been overestimated. Similarly, we found no evidence for emissions of chloroform (CHCl3) or methyl chloroform (CH3CCl3

  6. A view of Large Magellanic Cloud H II regions N159, N132, and N166 through the 345-GHz window

    NASA Astrophysics Data System (ADS)

    Paron, S.; Ortega, M. E.; Fariña, C.; Cunningham, M.; Jones, P. A.; Rubio, M.

    2016-01-01

    We present results obtained towards the H II regions N159, N166, and N132 from the emission of several molecular lines in the 345 GHz window. Using Atacama Submillimetre Telescope Experiment, we mapped a 2.4 arcmin × 2.4 arcmin region towards the molecular cloud N159-W in the 13CO J = 3-2 line and observed several molecular lines at an infrared (IR) peak very close to a massive young stellar object. 12CO and 13CO J = 3-2 were observed towards two positions in N166 and one position in N132. The 13CO J = 3-2 map of the N159-W cloud shows that the molecular peak is shifted south-west compared to the peak of the IR emission. Towards the IR peak, we detected emission from HCN, HNC, HCO+, C2H J = 4-3, CS J = 7-6, and tentatively C18O J = 3-2. This is the first reported detection of these molecular lines in N159-W. The analysis of the C2H line yields more evidence supporting that the chemistry involving this molecular species in compact and/or UC H II regions in the Large Magellanic Cloud should be similar to that in Galactic ones. A non-LTE (local thermodynamic equilibrium) study of the CO emission suggests the presence of both cool and warm gas in the analysed region. The same analysis for the CS, HCO+, HCN, and HNC shows that it is very likely that their emissions arise mainly from warm gas with a density between 5 × 105 to some 106 cm-3. The obtained HCN/HNC abundance ratio greater than 1 is compatible with warm gas and with an star-forming scenario. From the analysis of the molecular lines observed towards N132 and N166, we propose that both regions should have similar physical conditions, with densities of about 103 cm-3.

  7. Infrared Solar Spectroscopic Measurements of Free Tropospheric CO, C2H6, and HCN above Mauna Loa, Hawaii: Seasonal Variations and Evidence for Enhanced Emissions from the Southeast Asian Tropical Fires of 1997-1998

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Stephen, T. M.; Pougatchev, N. S.; Fishman, J.; David, S. J.; Blatherwick, R. D.; Novelli, P. C.; Jones, N. B.

    1999-01-01

    High spectral resolution (0.003 per cm) infrared solar absorption measurements of CO, C2H6, and HCN have been recorded at the Network for the Detection of Stratospheric Change station on Mauna Loa, Hawaii, (19.5N, 155.6W, altitude 3.4 km). The observations were obtained on over 250 days between August 1995 and February 1998. Column measurements are reported for the 3.4-16 km altitude region, which corresponds approximately to the free troposphere above the station. Average CO mixing ratios computed for this layer have been compared with flask sampling CO measurements obtained in situ at the station during the same time period. Both show asymmetrical seasonal cycles superimposed on significant variability. The first 2 years of observations exhibit a broad January-April maximum and a sharper CO minimum during late summer. The C2H6 and CO 3.4-16 km columns were highly correlated throughout the observing period with the C2H6/CO slope intermediate between higher and lower values derived from similar infrared spectroscopic measurements at 32'N and 45'S latitude, respectively. Variable enhancements in CO, C2H6, and particularly HCN were observed beginning in about September 1997. The maximum HCN free tropospheric monthly mean column observed in November 1997 corresponds to an average 3.4-16 km mixing ratio of 0.7 ppbv (1 ppbv = 10(exp -9) per unit volume), more than a factor of 3 above the background level. The HCN enhancements continued through the end of the observational series. Back-trajectory calculations suggest that the emissions originated at low northern latitudes in southeast Asia. Surface CO mixing ratios and the C2H6 tropospheric columns measured during the same time also showed anomalous autumn 1997 maxima. The intense and widespread tropical wild fires that burned during the strong El Nino warm phase of 1997- 1998 are the likely source of the elevated emission products.

  8. Characterization of mid-infrared emissions from C2H2, CO, CO2, and HCN-filled hollow fiber lasers

    NASA Astrophysics Data System (ADS)

    Jones, A. M.; Fourcade-Dutin, C.; Mao, C.; Baumgart, B.; Nampoothiri, A. V. V.; Campbell, N.; Wang, Y.; Benabid, F.; Rudolph, W.; Washburn, B. R.; Corwin, K. L.

    2012-02-01

    We have now demonstrated and characterized gas-filled hollow-core fiber lasers based on population inversion from acetylene (12C2H2) and HCN gas contained within the core of a kagome-structured hollow-core photonic crystal fiber. The gases are optically pumped via first order rotational-vibrational overtones near 1.5 μm using 1-ns pulses from an optical parametric amplifier. Transitions from the pumped overtone modes to fundamental C-H stretching modes in both molecules create narrow-band laser emissions near 3 μm. High gain resulting from tight confinement of the pump and laser light together with the active gas permits us to operate these lasers in a single pass configuration, without the use of any external resonator structure. A delay between the emitted laser pulse and the incident pump pulse has been observed and is shown to vary with pump pulse energy and gas pressure. Furthermore, we have demonstrated lasing beyond 4 μm from CO and CO2 using silver-coated glass capillaries, since fused silica based fibers do not transmit in this spectral region and chalcogenide fibers are not yet readily available. Studies of the laser pulse energy as functions of the pump pulse energy and gas pressure were performed. Efficiencies reaching ~ 20% are observed for both acetylene and CO2.

  9. Formation of N3, CH3, HCN, and HNC from the Far-UV Photolysis of CH4 in Nitrogen Ice

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The irradiation of pure solid N2 at 3 K with far-ultraviolet light from a synchrotron produced infrared absorption lines at 1657.7, 1655.6, and 1652.4 cm-1 and an ultraviolet absorption line at 272.0 nm, which are characteristic of the product N3. The threshold wavelength at which N3 was generated was 145.6 ± 2.9 nm, corresponding to an energy of 8.52 ± 0.17 eV. The photolysis of isotopically labeled 15N2 at 3 K consistently led to the formation of 15N3 with the same threshold wavelength of 145.6 ± 2.9 nm for its formation. The photolysis of CH4 in nitrogen ice in low concentrations also led to the formation of N3, together with CH3, HCN, and HNC, with the same threshold wavelength of 145.6 ± 2.9 nm. These results indicate that N3 radicals may play an important role in the photochemistry of nitrogen ices in astronomical environments.

  10. Molecular ions in the O-rich evolved star OH231.8+4.2: HCO+, H13CO+ and first detection of SO+, N2H+, and H3O+

    NASA Astrophysics Data System (ADS)

    Sánchez Contreras, C.; Velilla Prieto, L.; Agúndez, M.; Cernicharo, J.; Quintana-Lacaci, G.; Bujarrabal, V.; Alcolea, J.; Goicoechea, J. R.; Herpin, F.; Menten, K. M.; Wyrowski, F.

    2015-05-01

    OH 231.8+4.2, a bipolar outflow around a Mira-type variable star, displays a unique molecular richness amongst circumstellar envelopes (CSEs) around O-rich AGB and post-AGB stars. We report line observations of the HCO+ and H13CO+ molecular ions and the first detection of SO+, N2H+, and (tentatively) H3O+ in this source. SO+ and H3O+ have not been detected before in CSEs around evolved stars. These data have been obtained as part of a full mm-wave and far-IR spectral line survey carried out with the IRAM 30 m radio telescope and with Herschel/HIFI. Except for H3O+, all the molecular ions detected in this work display emission lines with broad profiles (FWHM ~ 50-90 km s-1), which indicates that these ions are abundant in the fast bipolar outflow of OH 231.8. The narrow profile (FWHM ~ 14 km s-1) and high critical densities (>106 cm-3) of the H3O+ transitions observed are consistent with this ion arising from denser, inner (and presumably warmer) layers of the fossil remnant of the slow AGB CSE at the core of the nebula. From rotational diagram analysis, we deduce excitation temperatures of Tex~ 10-20 K for all ions except for H3O+, which is most consistent with Tex≈ 100 K. Although uncertain, the higher excitation temperature suspected for H3O+ is similar to that recently found for H2O and a few other molecules, which selectively trace a previously unidentified, warm nebular component. The column densities of the molecular ions reported here are in the range Ntot≈ [1-8] × 1013 cm-2, leading to beam-averaged fractional abundances relative to H2 of X(HCO+) ≈ 10-8, X(H13CO+) ≈2 × 10-9, X(SO+) ≈4 × 10-9, X(N2H+) ≈2 × 10-9, and X(H3O+) ≈7 × 10-9 cm-2. We have performed chemical kinetics models to investigate the formation of these ions in OH 231.8 as the result of standard gas phase reactions initiated by cosmic-ray and UV-photon ionization. The model predicts that HCO+, SO+, and H3O+ can form with abundances comparable to the observed average values

  11. Hierarchical Porous LiNi1/3Co1/3Mn1/3O2 Nano-/Micro Spherical Cathode Material: Minimized Cation Mixing and Improved Li+ Mobility for Enhanced Electrochemical Performance

    PubMed Central

    Chen, Zhen; Wang, Jin; Chao, Dongliang; Baikie, Tom; Bai, Linyi; Chen, Shi; Zhao, Yanli; Sum, Tze Chien; Lin, Jianyi; Shen, Zexiang

    2016-01-01

    Although being considered as one of the most promising cathode materials for Lithium-ion batteries (LIBs), LiNi1/3Co1/3Mn1/3O2 (NCM) is currently limited by its poor rate performance and cycle stability resulting from the thermodynamically favorable Li+/Ni2+ cation mixing which depresses the Li+ mobility. In this study, we developed a two-step method using fluffy MnO2 as template to prepare hierarchical porous nano-/microsphere NCM (PNM-NCM). Specifically, PNM-NCM microspheres achieves a high reversible specific capacity of 207.7 mAh g−1 at 0.1 C with excellent rate capability (163.6 and 148.9 mAh g−1 at 1 C and 2 C), and the reversible capacity retention can be well-maintained as high as 90.3% after 50 cycles. This excellent electrochemical performance is attributed to unique hierarchical porous nano-/microsphere structure which can increase the contact area with electrolyte, shorten Li+ diffusion path and thus improve the Li+ mobility. Moreover, as revealed by XRD Rietveld refinement analysis, a negligible cation mixing (1.9%) and high crystallinity with a well-formed layered structure also contribute to the enhanced C-rates performance and cycle stability. On the basis of our study, an effective strategy can be established to reveal the fundamental relationship between the structure/chemistry of these materials and their properties. PMID:27185646

  12. Hierarchical Porous LiNi1/3Co1/3Mn1/3O2 Nano-/Micro Spherical Cathode Material: Minimized Cation Mixing and Improved Li(+) Mobility for Enhanced Electrochemical Performance.

    PubMed

    Chen, Zhen; Wang, Jin; Chao, Dongliang; Baikie, Tom; Bai, Linyi; Chen, Shi; Zhao, Yanli; Sum, Tze Chien; Lin, Jianyi; Shen, Zexiang

    2016-01-01

    Although being considered as one of the most promising cathode materials for Lithium-ion batteries (LIBs), LiNi1/3Co1/3Mn1/3O2 (NCM) is currently limited by its poor rate performance and cycle stability resulting from the thermodynamically favorable Li(+)/Ni(2+) cation mixing which depresses the Li(+) mobility. In this study, we developed a two-step method using fluffy MnO2 as template to prepare hierarchical porous nano-/microsphere NCM (PNM-NCM). Specifically, PNM-NCM microspheres achieves a high reversible specific capacity of 207.7 mAh g(-1) at 0.1 C with excellent rate capability (163.6 and 148.9 mAh g(-1) at 1 C and 2 C), and the reversible capacity retention can be well-maintained as high as 90.3% after 50 cycles. This excellent electrochemical performance is attributed to unique hierarchical porous nano-/microsphere structure which can increase the contact area with electrolyte, shorten Li(+) diffusion path and thus improve the Li(+) mobility. Moreover, as revealed by XRD Rietveld refinement analysis, a negligible cation mixing (1.9%) and high crystallinity with a well-formed layered structure also contribute to the enhanced C-rates performance and cycle stability. On the basis of our study, an effective strategy can be established to reveal the fundamental relationship between the structure/chemistry of these materials and their properties. PMID:27185646

  13. Fatigue in 0.5Li2MnO3:0.5Li(Ni1/3Co1/3Mn1/3)O2 positive electrodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Riekehr, Lars; Liu, Jinlong; Schwarz, Björn; Sigel, Florian; Kerkamm, Ingo; Xia, Yongyao; Ehrenberg, Helmut

    2016-09-01

    Two different Li-rich nickel-cobalt-manganese-oxide (Li-rich NCM) active materials with the same nominal composition 0.5Li2MnO3:0.5Li(Ni1/3Co1/3Mn1/3)O2 but different pristine nano structure have been analyzed structurally and electrochemically in different cycling states. For structural characterization, transmission electron microscopy (TEM) and high resolution synchrotron powder diffraction (S-XRD) experiments were conducted. The changes in structure with increasing cycle number are correlated with characteristic features in the corresponding electrochemical dQ/dV-profiles that were obtained by galvanostatically cycling the two different active materials. The presented data demonstrates that structural changes upon cycling, e.g. LiMnO2 and spinel formation, strongly depend on the degree oxygen is involved in the reversible charge compensation for delithiation/lithiation. According to our data, firstly a twin-like environment with nanometer dimensions is formed within the R-3m matrix during the initial cycle, which then gradually transforms into a spinel-like structure with increasing cycle number. As another result, we can show that Li2MnO3 to LiMnO2 transformation is not directly dependent in the irreversible oxygen loss in the first cycle but more importantly on transition metal migration. A model is presented explaining the dependency of LiMnO2 and spinel formation on the ability of Li-rich active materials to include oxygen in the charge compensation process.

  14. Quantifying Protein Synthesis and Degradation in Arabidopsis by Dynamic 13CO2 Labeling and Analysis of Enrichment in Individual Amino Acids in Their Free Pools and in Protein1[OPEN

    PubMed Central

    Fernie, Alisdair R.; Stitt, Mark

    2015-01-01

    Protein synthesis and degradation represent substantial costs during plant growth. To obtain a quantitative measure of the rate of protein synthesis and degradation, we supplied 13CO2 to intact Arabidopsis (Arabidopsis thaliana) Columbia-0 plants and analyzed enrichment in free amino acids and in amino acid residues in protein during a 24-h pulse and 4-d chase. While many free amino acids labeled slowly and incompletely, alanine showed a rapid rise in enrichment in the pulse and a decrease in the chase. Enrichment in free alanine was used to correct enrichment in alanine residues in protein and calculate the rate of protein synthesis. The latter was compared with the relative growth rate to estimate the rate of protein degradation. The relative growth rate was estimated from sequential determination of fresh weight, sequential images of rosette area, and labeling of glucose in the cell wall. In an 8-h photoperiod, protein synthesis and cell wall synthesis were 3-fold faster in the day than at night, protein degradation was slow (3%–4% d−1), and flux to growth and degradation resulted in a protein half-life of 3.5 d. In the starchless phosphoglucomutase mutant at night, protein synthesis was further decreased and protein degradation increased, while cell wall synthesis was totally inhibited, quantitatively accounting for the inhibition of growth in this mutant. We also investigated the rates of protein synthesis and degradation during leaf development, during growth at high temperature, and compared synthesis rates of Rubisco large and small subunits of in the light and dark. PMID:25810096

  15. Hierarchical Porous LiNi1/3Co1/3Mn1/3O2 Nano-/Micro Spherical Cathode Material: Minimized Cation Mixing and Improved Li+ Mobility for Enhanced Electrochemical Performance

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Wang, Jin; Chao, Dongliang; Baikie, Tom; Bai, Linyi; Chen, Shi; Zhao, Yanli; Sum, Tze Chien; Lin, Jianyi; Shen, Zexiang

    2016-05-01

    Although being considered as one of the most promising cathode materials for Lithium-ion batteries (LIBs), LiNi1/3Co1/3Mn1/3O2 (NCM) is currently limited by its poor rate performance and cycle stability resulting from the thermodynamically favorable Li+/Ni2+ cation mixing which depresses the Li+ mobility. In this study, we developed a two-step method using fluffy MnO2 as template to prepare hierarchical porous nano-/microsphere NCM (PNM-NCM). Specifically, PNM-NCM microspheres achieves a high reversible specific capacity of 207.7 mAh g‑1 at 0.1 C with excellent rate capability (163.6 and 148.9 mAh g‑1 at 1 C and 2 C), and the reversible capacity retention can be well-maintained as high as 90.3% after 50 cycles. This excellent electrochemical performance is attributed to unique hierarchical porous nano-/microsphere structure which can increase the contact area with electrolyte, shorten Li+ diffusion path and thus improve the Li+ mobility. Moreover, as revealed by XRD Rietveld refinement analysis, a negligible cation mixing (1.9%) and high crystallinity with a well-formed layered structure also contribute to the enhanced C-rates performance and cycle stability. On the basis of our study, an effective strategy can be established to reveal the fundamental relationship between the structure/chemistry of these materials and their properties.

  16. FTIR time-series of biomass burning products (HCN, C2H6, C2H2, CH3OH, and HCOOH) at Reunion Island (21° S, 55° E) and comparisons with model data

    NASA Astrophysics Data System (ADS)

    Vigouroux, C.; Stavrakou, T.; Whaley, C.; Dils, B.; Duflot, V.; Hermans, C.; Kumps, N.; Metzger, J.-M.; Scolas, F.; Vanhaelewyn, G.; Müller, J.-F.; Jones, D. B. A.; Li, Q.; De Mazière, M.

    2012-11-01

    Reunion Island (21° S, 55° E), situated in the Indian Ocean at about 800 km east of Madagascar, is appropriately located to monitor the outflow of biomass burning pollution from Southern Africa and Madagascar, in the case of short-lived compounds, and from other Southern Hemispheric landmasses such as South America, in the case of longer-lived species. Ground-based Fourier transform infrared (FTIR) solar absorption observations are sensitive to a large number of biomass burning products. We present in this work the FTIR retrieval strategies, suitable for very humid sites such as Reunion Island, for hydrogen cyanide (HCN), ethane (C2H6), acetylene (C2H2), methanol (CH3OH), and formic acid (HCOOH). We provide their total columns time-series obtained from the measurements during August-October 2004, May-October 2007, and May 2009-December 2010. We show that biomass burning explains a large part of the observed seasonal and interannual variability of the chemical species. The correlations between the daily mean total columns of each of the species and those of CO, also measured with our FTIR spectrometer at Reunion Island, are very good from August to November (R ≥ 0.86). This allows us to derive, for that period, the following enhancement ratios with respect to CO: 0.0047, 0.0078, 0.0020, 0.012, and 0.0046 for HCN, C2H6, C2H2, CH3OH, and HCOOH, respectively. The HCN ground-based data are compared to the chemical transport model GEOS-Chem, while the data for the other species are compared to the IMAGESv2 model. We show that using the HCN/CO ratio derived from our measurements (0.0047) in GEOS-Chem reduces the underestimation of the modeled HCN columns compared with the FTIR measurements. The comparisons between IMAGESv2 and the long-lived species C2H6 and C2H2 indicate that the biomass burning emissions used in the model (from the GFED3 inventory) are probably underestimated in the late September-October period for all years of measurements, and especially in

  17. SIMULTANEOUS OBSERVATIONS OF COMET C/2002 T7 (LINEAR) WITH THE BERKELEY-ILLINOIS-MARYLAND ASSOCIATION AND OWENS VALLEY RADIO OBSERVATORY INTERFEROMETERS: HCN AND CH{sub 3}OH

    SciTech Connect

    Hogerheijde, Michiel R.; Qi Chunhua; De Pater, Imke; Wright, M. C. H.; Blake, Geoffrey A.; Friedel, D. N.; Snyder, L. E.; Forster, J. R.; Palmer, Patrick; Remijan, Anthony J.

    2009-06-15

    We present observations of HCN J = 1-0 and CH{sub 3}OH J(K{sub a} , K{sub c} ) = 3(1, 3)-4(0, 4) A{sup +} emission from comet C/2002 T7 (LINEAR) obtained simultaneously with the Owens Valley Radio Observatory (OVRO) and Berkeley-Illinois-Maryland Association (BIMA) millimeter interferometers. We combined the data from both arrays to increase the (u, v) sampling and signal to noise of the detected line emission. We also report the detection of CH{sub 3}OH J(K{sub a} , K{sub c} ) = 8(0, 8)-7(1, 7) A{sup +} with OVRO data alone. Using a molecular excitation code that includes the effects of collisions with water and electrons, as well as pumping by the Solar infrared photons (for HCN alone), we find a production rate of HCN of 2.9 x 10{sup 26} s{sup -1} and for CH{sub 3}OH of 2.2 x 10{sup 27} s{sup -1}. Compared to the adopted water production rate of 3 x 10{sup 29} s{sup -1}, this corresponds to an HCN/H{sub 2}O ratio of 0.1% and a CH{sub 3}OH/H{sub 2}O ratio of 0.7%. We critically assess the uncertainty of these values due to the noise ({approx}10%), the uncertainties in the adopted comet model ({approx}50%), and the uncertainties in the adopted collisional excitation rates (up to a factor of 2). Pumping by Solar infrared photons is found to be a minor effect for HCN, because our 15'' synthesized beam is dominated by the region in the coma where collisions dominate. Since the uncertainties in the derived production rates are at least as large as one-third of the differences found between comets, we conclude that reliable collision rates and an accurate comet model are essential. Because the collisionally dominated region critically depends on the water production rate, using the same approximate method for different comets may introduce biases in the derived production rates. Multiline observations that directly constrain the molecular excitation provide much more reliable production rates.

  18. Electrophysiological and Immunohistochemical Evidence for an Increase in GABAergic Inputs and HCN Channels in Purkinje Cells that Survive Developmental Ethanol Exposure.

    PubMed

    Light, Kim E; Hayar, Abdallah M; Pierce, Dwight R

    2015-08-01

    Ethanol exposures during the early postnatal period of the rat result in significant death of Purkinje cells (PCs). The magnitude, time-course, and lobular specificity of PC death have been well characterized in several studies. Additionally, significant reduction of climbing fiber inputs to the surviving PCs has been characterized. This study investigates whether further alterations to the cerebellar cortical circuits might occur as a result of developmental ethanol exposures. We first examined the firing pattern of PCs in acute slice preparations on postnatal days 13-15. While the basic firing frequency was not significantly altered, PCs from rat pups treated with ethanol on postnatal days 4-6 showed a significantly increased number of inhibitory postsynaptic potentials (IPSCs) and a larger Ih current. We conducted immunofluorescent studies to identify the probable cause of the increased IPSCs. We found a significant 21 % increase in the number of basket cells per PC and a near doubling of the volume of co-localized basket cell axonal membrane with PC. In addition, we identified a significant (~147 %) increase in HCN1 channel volume co-localized to PC volume. Therefore, the cerebellar cortex that survives targeted postnatal ethanol exposure is dramatically altered in development subsequent to PC death. The cerebellar cortical circuit that results is one that operates under a significant degree of increased resting inhibition. The alterations in the development of cerebellar circuitry following ethanol exposure, and the significant loss of PCs, could result in modifications of the structure and function of other brain regions that receive cerebellar inputs. PMID:25667035

  19. Experimental investigation of aminoacetonitrile formation through the Strecker synthesis in astrophysical-like conditions: reactivity of methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN)

    NASA Astrophysics Data System (ADS)

    Danger, G.; Borget, F.; Chomat, M.; Duvernay, F.; Theulé, P.; Guillemin, J.-C.; Le Sergeant D'Hendecourt, L.; Chiavassa, T.

    2011-11-01

    Context. Studing chemical reactivity in astrophysical environments is an important means for improving our understanding of the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. Laboratory simulations of the reactivity of ice analogs provide important insight into the reactivity in these environments. Here, we use these experimental simulations to investigate the Strecker synthesis leading to the formation of aminoacetonitrile in astrophysical-like conditions. The aminoacetonitrile is an interesting compound because it was detected in SgrB2, hence could be a precursor of the smallest amino acid molecule, glycine, in astrophysical environments. Aims: We present the first experimental investigation of the formation of aminoacetonitrile NH2CH2CN from the thermal processing of ices including methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN) in interstellar-like conditions without VUV photons or particules. Methods: We use Fourier Transform InfraRed (FTIR) spectroscopy to monitor the ice evolution during its warming. Infrared spectroscopy and mass spectroscopy are then used to identify the aminoacetonitrile formation. Results: We demonstrate that methanimine can react with -CN during the warming of ice analogs containing at 20 K methanimine, ammonia, and [NH4+ -CN] salt. During the ice warming, this reaction leads to the formation of poly(methylene-imine) polymers. The polymer length depend on the initial ratio of mass contained in methanimine to that in the [NH4+ -CN] salt. In a methanimine excess, long polymers are formed. As the methanimine is progressively diluted in the [NH4+ -CN] salt, the polymer length decreases until the aminoacetonitrile formation at 135 K. Therefore, these results demonstrate that aminoacetonitrile can be formed through the second step of the Strecker synthesis in astrophysical-like conditions.

  20. Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber)

    PubMed Central

    Gessele, Nikodemus; Garcia-Pino, Elisabet; Omerbašić, Damir; Park, Thomas J.; Koch, Ursula

    2016-01-01

    Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals. PMID:26760498

  1. Short-term carbon dynamics in a temperate heathland upon six years of exposure to elevated CO2 concentration, drought and warming: Evidence from an in-situ 13CO2 pulse-chase experiment

    NASA Astrophysics Data System (ADS)

    Ambus, P.; Reinsch, S.; Sárossy, Z.; Egsgaard, H.; Jakobsen, I.; Michelsen, A.; Schmidt, I.; Nielsen, P.

    2013-12-01

    An in-situ 13CO2 pulse-labeling experiment was carried out in a temperate heathland (8 oC MAT, 610 mm MAP) to study the impact on short-term carbon (C) allocation as affected by elevated CO2 concentration (+120 ppm), prolonged summer droughts (ca. -43 mm) and warming (+1 oC). The study was carried out six years after the climate treatments were initiated and took place in the early growing season in May in vegetation dominated by grasses, mainly Deschampsia flexuosa. Newly assimilated C (13C from the pulse-label) was traced into vegetation, soil and soil microorganisms and belowground respiration 1, 2 and 8 days after pulse-labeling. The importance of the microbial community in C utilization was investigated using 13C enrichment patterns in different microbial functional groups on the basis of phospholipid fatty acid (PLFA) profiles. Climate treatments did not affect microorganism abundance in soil or rhizosphere fractions in terms of total PLFA-C concentration. Elevated CO2 significantly reduced the abundance of gram-negative bacteria (17:0cy), but did not affect the abundance of decomposers (fungi and actinomycetes) in rhizosphere fractions. Drought favored the bacterial community in rhizosphere fractions whereas warming reduced the abundance of gram-negative bacteria (19:0cy) and changed the actinomycetes community (10Me16:0, 10Me18:0). Fastest and highest utilization of recently assimilated C was observed in rhizosphere associated gram-negative bacteria followed by gram-positive bacteria. The utilization of recently assimilated C by the microbial community was faster under elevated CO2 conditions compared to ambient. The 13C assimilation by green plant tissue and translocation to roots was significantly reduced by the extended summer drought. Under elevated CO2 conditions we observed an increased amount of 13C in the litter fraction. The assimilation of 13C by vegetation was not changed when the climate factors were applied in combination. The total amount of

  2. Implications of high-precision measurements of 13C-18O bond ordering in CO2 for thermometry in modern bivalved mollusc shells

    NASA Astrophysics Data System (ADS)

    Petrizzo, Daniel A.; Young, Edward D.; Runnegar, Bruce N.

    2014-10-01

    We report a temperature calibration for Δ47 from bivalve carbonate that lies within error of theoretical predictions (Schauble et al., 2006; Guo et al., 2009). The temperature sensitivity of this calibration is lower than several different earlier calibrations determined using either inorganic calcite, corals, foraminiferans and coccoliths, or brachiopods and bivalved molluscs, but it agrees with more recent Δ47-temperature relationships determined from measurements of clumped-isotopes in mollusc and brachiopod shells. We demonstrate that mollusc shell temperature calibrations originating from different laboratories that have not been corrected for instrument backgrounds may differ by as much as ∼0.07‰ in Δ47 over the ∼0 to 30 °C temperature range even where dΔ47/dT agree. Because recent calibrations for Δ47 vs. T from several different laboratories agree for bivalved mollusc shells, yet differ from an early calibration for bivalved molluscs, we suggest it is unlikely that temperature-Δ47 variability is attributable to phylum-specific vital effects, and instead conclude that differences in calibration slope between phyla and/or inorganic calcite are more easily explained by variability in measurements made in different laboratories. Discrepancies in both calibration slopes and/or intercepts indicate that Δ47 values measured in natural materials may be more significantly influenced by instrument-specific effects, as well as effects from sample preparation and handling and purification of CO2 than current techniques are able to correct for, and therefore, temperatures obtained by comparing measurements of Δ47 to independently determined calcite calibrations may err by a far greater amount than acknowledged in previous studies.

  3. Comparing three methods of NEE-flux partitioning from the same grassland ecosystem: the 13C, 18O isotope approach and using simulated Ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Siegwolf, R.; Bantelmann, E.; Saurer, M.; Eugster, W.; Buchmann, N.

    2007-12-01

    As a change in the global climate occurs with increasing temperatures, the Carbon exchange processes of terrestrial ecosystems will change as well. However, it is difficult to quantify the degree to what ecosystem respiration will change relative to the CO2 uptake by photosynthesis. To estimate the carbon sequestration potential of terrestrial vegetation cover it is essential to know both fluxes: ecosystem respiration and the carbon uptake by the vegetation cover. Therefore the net ecosystem exchange of CO2 (NEE) was measured with the eddy covariance method and separated into assimilation and respiration flux. We applied three different approaches, 1) the conventional method, applying the nighttime relationship between soil temperature and NEE for calculating the respiration flux during the day, 2) the use of stable carbon and 3) oxygen isotopes. We compared the results of the three partitioning exercises for a temperate grassland ecosystem in the pre-Alps of Switzerland for four days in June 2004. The assimilation flux derived with the conventional NEE partitioning approach, was best represented at low PAR and low temperatures, in the morning between 5 and 9 am. With increasing temperature and PAR the assimilation for the whole canopy was underestimated. For partitioning NEE via 18O approach, correlations of temperature and radiation with assimilation and respiration flux were significantly higher for the partitioning approach with 18O than for the 13C NEE partitioning. A sensitivity analysis showed the importance of an accurate determination of the equilibrium term θ between CO2 and leaf water δ18O for the NEE partitioning with 18O. For using 13C to partition NEE, the correct magnitude of the 13C fractionation and for the respiration term is essential. The analysis of the data showed that for low light and low morning temperatures the conventional method delivers reasonably good results. When the temperatures exceeded 21°C the isotope approach provided the more realistic results, particularly the use of the oxygen isotopes. These results represent the situation for this particular grassland in the Swiss Alps while in other ecosystems the three partitioning approaches could show different results with regard to the quality and precision of the flux separation. In the presentation the potential reasons for the variation of the three approaches will be discussed.

  4. The ALMA and HST Views of the Molecular Gas and Star Formation in the Prototypical Barred Spiral Galaxy NGC 1097

    NASA Astrophysics Data System (ADS)

    Sheth, Kartik; Regan, Michael W.; Kim, Taehyun; Kohno, Kotaro; Martin, Sergio; Villard, Eric; Onishi, Kyoko

    2016-01-01

    We mapped the entire inner disk of NGC 1097 (the circumnuclear ring, bar ends, the bar and inner spiral arms) using ALMA in the CO J=1-0 line at resolution of 1" (~65 pc). We also mapped the northern half of the bar in every other common molecular gas tracer at 3mm (HCN, HCO+, C18O, 13CO, C34S). Together these data provide the most detailed and highest resolution map of the molecular gas distribution and kinematics in a nearby barred spiral, rivalling the incredible maps seen for galaxies like M51 in the northern hemisphere. The data show the impact of the different environments in the galaxy as well as evidence for a multi-phased molecular medium. The data also evidence how the shear induced by the bar shock completely inhibits the star formation activity in the inner ends of the bar (clearly showing an anti-correlation between the strength of the CO line emission and Halpha emission). We will also present multiwavelength HST observations of the galaxy which are used to identify and map star clusters across the inner disk of the galaxy. We use these data to understand how star formation proceeds from one environment to the next across the galaxy.

  5. Study for Planck Cold Clumps with molecular lines

    NASA Astrophysics Data System (ADS)

    Wu, Yuefang

    2014-07-01

    To probe dynamical processes and physical properties of Planck Cold Clumps, we have observed 674 of the most reliable 915 sources with J=1-0 of CO,13CO and C18O using PMO 13.7 m telescope of Purple Mountain Observatory. J=1-0 lines of HCO+ and HCN at CO emission peaks were also observed, of which 24 were mapped with IRAM 30 m telescope. Results show excitation temperatures are from 4 to 17 K, and column densities range from 1020 to 4.5x1023 cm-2. Planck cold clumps have the smallest line width among samples of IRDCs, weak IRAS, EGOs, UC HII candidates and methanol maser chosen cores. However the lines are still wider than those of low-mass cores and have non-thermal supersonic dispersion. Filament is the majority in their morphologies and fragmented structures were found with dense molecular lines. More than 70% of CO cores are starless. Planck cold clumps seem to be ideal samples to search for candidates of massive prestellar cores and pre-clusters.

  6. The IRAM 30m Nearby Galaxy Dense Gas Survey

    NASA Astrophysics Data System (ADS)

    Bigiel, Frank

    2015-08-01

    I will present work in progress from EMPIRE, a large program (~440 hr) with the EMIR receiver at the IRAM 30m telescope to map dense gas tracers (HCN, HCO+, HNC, N2H+, C2H etc.) as well as the optically thin 1-0 lines of 13CO and C18O for the first time systematically across the disks of 9 nearby spiral galaxies. Building on a large suite of available ancillary data from the radio to the UV, we will be able to study, among other things, dense gas fractions and star formation efficiencies and how they vary with environment within and among nearby disk galaxies. While the survey has only recently started, we have similar data from a pilot program in M51 as well as from an ancillary study with CARMA in the Antennae Galaxies. I will present results from these two studies, provide an outlook and show first data from EMPIRE, and place our work in context with other work, including existing studies of dense gas tracers in other galaxies as well as our HERACLES CO and THINGS HI surveys.

  7. Infrared Solar Spectroscopic Measurements of Free Tropospheric CO, C2H6, and HCN above Mauna Loa, Hawaii: Seasonal Variations and Evidence for Enhanced Emissions from the Southeast Asian Fires of 1997-1998. Revised

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Stephen, T. M.; Pougatchev, N. S.; Fishman, J.; David, S. J.; Blatherwick, R. D.; Novelli, P. C.; Jones, N. B.; Connor, B. J.

    1999-01-01

    High spectral resolution (0.003/ cm) infrared solar absorption measurements of CO, C2H6, and HCN have been recorded at the Network for the Detection of Stratospheric Change station on Mauna Loa, Hawaii, (19.5 deg N, 155.6 deg W, altitude 3.4 km). The observations were obtained on over 250 days between August 1995 and February 1998. Column measurements are reported for the 3.4 - 16 km altitude region, which corresponds approximately to the free troposphere above the station. Average CO mixing ratios computed for this layer have been compared with flask sampling CO measurements obtained in situ at the station during the same time period. Both show asymmetrical seasonal cycles superimposed on significant variability. The first two years of observations exhibit a broad January-April maximum and a sharper CO minimum during late summer. The C2H6 and CO 3.4 - 16 km columns were highly correlated throughout the observing period with the C2H6/CO slope intermediate between higher and lower values derived from similar infrared spectroscopic measurements at 32 deg N and 45 deg S latitude, respectively. Variable enhancements in CO, C2H6, and particularly HCN were observed beginning in about September 1997. The maximum HCN free tropospheric monthly mean column observed in November 1997 corresponds to an average 3.4 - 16 km mixing ratio of 0.7 ppbv (1 ppbv = 10(exp -9) per unit volume), more than a factor of 3 above the background level. The HCN enhancements continued through the end of the observational series. Back-trajectory calculations suggest that the emissions originated at low northern latitudes in southeast Asia. Surface CO mixing ratios and the C2H6 tropospheric columns measured during the same time also showed anomalous autumn 1997 maxima. The intense and widespread tropical wild fires that burned during 3 the strong El Nino warm phase of 1997-1998 are the likely source of the elevated emission products.

  8. Nitrogen isotopic ratios in Barnard 1: a consistent study of the N2H+, NH3, CN, HCN, and HNC isotopologues

    NASA Astrophysics Data System (ADS)

    Daniel, F.; Gérin, M.; Roueff, E.; Cernicharo, J.; Marcelino, N.; Lique, F.; Lis, D. C.; Teyssier, D.; Biver, N.; Bockelée-Morvan, D.

    2013-12-01

    Context. The 15N isotopologue abundance ratio measured today in different bodies of the solar system is thought to be connected to 15N-fractionation effects that would have occurred in the protosolar nebula. Aims: The present study aims at putting constraints on the degree of 15N-fractionation that occurs during the prestellar phase, through observations of D, 13C, and 15N-substituted isotopologues towards B1b. Molecules both from the nitrogen hydride family, i.e. N2H+, and NH3, and from the nitrile family, i.e. HCN, HNC, and CN, are considered in the analysis. Methods: As a first step, we modelled the continuum emission in order to derive the physical structure of the cloud, i.e. gas temperature and H2 density. These parameters were subsequently used as input in a non-local radiative transfer model to infer the radial abundance profiles of the various molecules. Results: Our modelling shows that all the molecules are affected by depletion onto dust grains in the region that encompasses the B1-bS and B1-bN cores. While high levels of deuterium fractionation are derived, we conclude that no fractionation occurs in the case of the nitrogen chemistry. Independently of the chemical family, the molecular abundances are consistent with 14N/15N ~ 300, a value representative of the elemental atomic abundances of the parental gas. Conclusions: The inefficiency of the 15N-fractionation effects in the B1b region can be linked to the relatively high gas temperature ~17 K, which is representative of the innermost part of the cloud. Since this region shows signs of depletion onto dust grains, we cannot exclude the possibility that the molecules were previously enriched in 15N, earlier in the B1b history and that such an enrichment could have been incorporated into the ice mantles. It is thus necessary to repeat this kind of study in colder sources to test such a possibility.

  9. Azotobacter vinelandii vanadium nitrogenase: formaldehyde is a product of catalyzed HCN reduction, and excess ammonia arises directly from catalyzed azide reduction.

    PubMed

    Fisher, Karl; Dilworth, Michael J; Newton, William E

    2006-04-01

    The Mo-nitrogenase-catalyzed reduction of both cyanide and azide results in the production of excess NH3, which is an amount of NH3 over and above that expected to be formed from the well-recognized reactions. Several suggestions about the possible sources of excess NH3 have been made, but previous attempts to characterize these reactions have met with either limited (or no) success or controversy. Because V-nitrogenase has a propensity to release partially reduced intermediates, e.g., N2H4 during N2 reduction, it was selected to probe the reduction of cyanide and azide. Sensitive assay procedures were developed and employed to monitor the production of either HCHO or CH3OH (its further two-electron-reduced product) from HCN. Like Mo-nitrogenase, V-nitrogenase suffered electron-flux inhibition by CN- (but was much less sensitive than Mo-nitrogenase), but unlike the case for Mo-nitrogenase, MgATP hydrolysis was also inhibited by CN-. V-Nitrogenase also released more of the four-electron-reduced intermediate, CH3NH2, than did Mo-nitrogenase. At high NaCN concentrations, V-nitrogenase directed a significant percentage of electron flux into excess NH3, and under these conditions, substantial amounts of HCHO, but no CH3OH, were detected for the first time. With azide, in contrast to the case for Mo-nitrogenase, both total electron flux and MgATP hydrolysis with V-nitrogenase were inhibited. V-Nitrogenase, unlike Mo-nitrogenase, showed no preference between the two-electron reduction to N2-plus-NH3 and the six-electron reduction to N2H4-plus-NH3. V-Nitrogenase formed more excess NH3, but reduction of the N2 produced by the two-electron reduction of N3(-) was not its source. Rather, it was formed directly by the eight-electron reduction of N3(-). Unlike Mo-nitrogenase, CO could not completely eliminate either cyanide or azide reduction by V-nitrogenase. CO did, however, eliminate the inhibition of both electron flux and MgATP hydrolysis by CN-, but not that caused by

  10. Trends of OCS, HCN, SF6, CHClF2 (HCFC-22) in the Lower Stratosphere from 1985 and 1994 Atmospheric Trace Molecule Spectroscopy Experiment Measurements Near 30 deg. North Latitude

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Mahieu, E.; Zander, R.; Gunson, M. R.; Salawitch, R. J.; Chang, A. Y.; Goldman, A.; Abrams, M. C.; Abbas, M. M.; Newchurch, M. J.; Irion, F. W.

    1996-01-01

    Volume mixing ratio (VMR) profiles of OCS, HCN, SF6, and CHClF2 (HCFC-22) have been measured near 30 deg N latitude by the Atmospheric Trace Molecule Spectroscopy Fourier transform spectrometer during shuttle flights on 29 April - 6 May 1985 and 3-2 November 1994. The change in the concentration of each molecule in the lower stratosphere has been derived for this 9 1/2-year period by comparing measurements between potential temperatures of 395 to 800 K (approximately 17 to 30 km altitude) relative to simultaneously measured values of the long-lived tracer N2O. Exponential rates of increase inferred for 1985-to 1994 from these comparisons are (0.1 plus or minus 0.4)% yr(exp-1) for OCS, (1.0 plus or minus 1.0)% yr(exp-1) for HCN, (8.0 +/- 0.7)% yr(exp-1) for SF6, and (8.0 +/- 1.0)% yr(exp-1) for CHClF2 (HCFC-22), 1 sigma. The lack of an appreciable trend for OCS suggests the background (i.e. nonvolcanic) source of stratospheric aerosol was the same during the two periods. These results are compared with trends reported in the literature.

  11. A SIFT ion-molecule study of some reactions in Titan's atmosphere. reactions of N(+), N(2)(+), and HCN(+) with CH(4), C(2)H(2), and C(2)H(4)

    NASA Technical Reports Server (NTRS)

    Anicich, Vincent G.; Wilson, Paul; McEwan, Murray J.

    2004-01-01

    The results of a study of the ion-molecule reactions of N(+), N(2)(+), and HCN(+) with methane, acetylene, and ethylene are reported. These studies were performed using the FA-SIFT at the University of Canterbury. The reactions studied here are important to understanding the ion chemistry in Titan's atmosphere. N(+) and N(2)(+) are the primary ions formed by photo-ionization and electron impact in Titan's ionosphere and drive Titan's ion chemistry. It is therefore very important to know how these ions react with the principal trace neutral species in Titan's atmosphere: Methane, acetylene, and ethylene. While these reactions have been studied before the product channels have been difficult to define as several potential isobaric products make a definitive answer difficult. Mass overlap causes difficulties in making unambiguous species assignments in these systems. Two discriminators have been used in this study to resolve the mass overlap problem. They are deuterium labeling and also the differences in reactivities of each isobar with various neutral reactants. Several differences have been found from the products in previous work. The HCN(+) ion is important in both Titan's atmosphere and in the laboratory.

  12. Microstructure of Li(Mn{sub 1/3}Ni{sub 1/3}Co{sub 1/3})O{sub 2} cathode material for lithium ion battery: Dependence of crystal structure on calcination and heat-treatment temperature

    SciTech Connect

    Kabi, S.; Ghosh, A.

    2013-09-01

    Graphical abstract: TEM micrograph of Li(Mn{sub 1/3}Ni{sub 1/3}Co{sub 1/3})O{sub 2} compound calcined at 900 °C. - Highlights: • Synthesis condition of Li(Mn{sub 1/3}Ni{sub 1/3}Co{sub 1/3})O{sub 2} compound was optimized. • Effect of calcination and heat treatment on the structure was investigated. • Controlled heat-treatment reduced cation mixing and improved structural ordering. • Calcination and heat-treatment condition affected distribution of particle size. - Abstract: Cathode compounds of composition Li(Mn{sub 1/3}Ni{sub 1/3}Co{sub 1/3})O{sub 2} have been prepared by calcination of the precursor materials at 700, 800, 900 and 1000 °C for 24 h and by subsequent heat-treatments at 1100 °C for 4–6 h. It has been observed that the structural ordering and particle size increase with increasing calcination temperature. The compounds calcined at 700 °C and 800 °C are not well-crystallized, but the distribution of particles is uniform. However, the compounds calcined at 900 °C and 1000 °C are well-crystallized with a non-uniform distribution of particles. The compounds calcined at 900 °C are well-crystallized with a well-ordered hexagonal structure. The samples calcined at 800 °C and heat treated at 1100 °C for 4 h also show same structure. They have smooth surface morphology with uniform distribution of particles in the sub-micron (0.15–0.40 μm) range and less amount of cation mixing.

  13. Five years of CO, HCN, C2H6, C2H2, CH3OH, HCOOH, and H2CO total columns measured in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Viatte, C.; Strong, K.; Walker, K. A.; Drummond, J. R.

    2013-12-01

    We present a five-year timeseries of seven tropospheric species measured using a ground-based Fourier Transform InfraRed (FTIR) spectrometer at the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, Canada, 80°05' N, 86°42' W) from 2007 to 2011. Total columns and temporal variabilities of carbon monoxide (CO), hydrogen cyanide (HCN), and ethane (C2H6), as well as the first derived total columns at Eureka of acetylene (C2H2), methanol (CH3OH), formic acid (HCOOH), and formaldehyde (H2CO) are investigated, providing a new dataset in the sparsely sampled high latitudes. Total columns are obtained using the SFIT2 retrieval algorithm based on the Optimal Estimation Method. The microwindows, as well as the a priori profiles and variabilities are selected to optimize the information content of the retrievals, and error analyses are performed for all seven species. Our retrievals show good sensitivities in the troposphere. The seasonal amplitudes of the timeseries, ranging from 34 to 104%, are captured while using a single a priori profile for each species. The timeseries of the CO, C2H6 and C2H2 total columns at PEARL exhibit strong seasonal cycles with maxima in winter and minima in summer, in opposite phase to the HCN, CH3OH, HCOOH and H2CO timeseries. These cycles result from the relative contributions of the photochemistry, oxidation, and transport, as well as biogenic and biomass burning emissions. Comparisons of the FTIR partial columns with coincident satellite measurements by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) show good agreement. The correlation coefficients and the slopes range from 0.56 to 0.97, and 0.50 to 3.35, respectively, for the seven target species. Our new dataset is compared with previous measurements found in the literature to assess atmospheric budgets of these tropospheric species in the high Arctic. The CO and C2H6 concentrations are consistent with negative trends observed over

  14. Five years of CO, HCN, C2H6, C2H2, CH3OH, HCOOH and H2CO total columns measured in the Canadian high Arctic

    NASA Astrophysics Data System (ADS)

    Viatte, C.; Strong, K.; Walker, K. A.; Drummond, J. R.

    2014-06-01

    We present a five-year time series of seven tropospheric species measured using a ground-based Fourier transform infrared (FTIR) spectrometer at the Polar Environment Atmospheric Research Laboratory (PEARL; Eureka, Nunavut, Canada; 80°05' N, 86°42' W) from 2007 to 2011. Total columns and temporal variabilities of carbon monoxide (CO), hydrogen cyanide (HCN) and ethane (C2H6) as well as the first derived total columns at Eureka of acetylene (C2H2), methanol (CH3OH), formic acid (HCOOH) and formaldehyde (H2CO) are investigated, providing a new data set in the sparsely sampled high latitudes. Total columns are obtained using the SFIT2 retrieval algorithm based on the optimal estimation method. The microwindows as well as the a priori profiles and variabilities are selected to optimize the information content of the retrievals, and error analyses are performed for all seven species. Our retrievals show good sensitivities in the troposphere. The seasonal amplitudes of the time series, ranging from 34 to 104%, are captured while using a single a priori profile for each species. The time series of the CO, C2H6 and C2H2 total columns at PEARL exhibit strong seasonal cycles with maxima in winter and minima in summer, in opposite phase to the HCN, CH3OH, HCOOH and H2CO time series. These cycles result from the relative contributions of the photochemistry, oxidation and transport as well as biogenic and biomass burning emissions. Comparisons of the FTIR partial columns with coincident satellite measurements by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) show good agreement. The correlation coefficients and the slopes range from 0.56 to 0.97 and 0.50 to 3.35, respectively, for the seven target species. Our new data set is compared to previous measurements found in the literature to assess atmospheric budgets of these tropospheric species in the high Arctic. The CO and C2H6concentrations are consistent with negative trends observed over the

  15. VizieR Online Data Catalog: Planck cold clumps survey in the Orion complex (Liu+, 2012)

    NASA Astrophysics Data System (ADS)

    Liu, T.; Wu, Y.; Zhang, H.

    2012-10-01

    Observations of 51 Planck cold clumps (from the survey of Wu et al. 2012, Cat. J/ApJ/756/76) in the Orion complex in 12CO (1-0), 13CO (1-0), and C18O (1-0) were carried out with the PMO 13.7m radio telescope from 2011 April to June. (4 data files).

  16. VizieR Online Data Catalog: CH3OH maser sources (Liu+,

    NASA Astrophysics Data System (ADS)

    Liu, T.; Wu, Y.-F.; Wang, K.

    2011-10-01

    The observations were made in January 2008 with the 13.7m telescope of PMO at Qinghai Station. The 12CO, 13CO and C18O (J=1-0) lines were observed simultaneously by a superconductor receiver. (1 data file).

  17. VizieR Online Data Catalog: Planck cold clumps and cores in the 2nd quadrant (Zhang+, 2016)

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Wu, Y.; Liu, T.; Meng, F.

    2016-07-01

    Observations of 96 Planck Cold Clumps in the second quadrant in the J=1-0 12CO, 13CO, and C18O lines were carried out using the 13.7m telescope of Purple Mountain Observatory (PMO), Chinese Academy of Sciences, during 2011 April-May and 2011 December-2012 January. (3 data files).

  18. VizieR Online Data Catalog: Coalsack CO maps (Beuther+, 2011)

    NASA Astrophysics Data System (ADS)

    Beuther, H.; Kainulainen, J.; Henning, T.; Plume, R.; Heitsch, F.

    2011-07-01

    The C18O(2-1) and 13CO(2-1) data at 219.560GHz and observed simultaneously with the Atacama Pathfinder Experiment (APEX) between April and June 2010 in the 1mm band for the two regions R1 and R2 marked in Fig. 1 in on-the-fly mode. (2 data files).

  19. VizieR Online Data Catalog: Methanol maser associated outflows (de Villiers+, 2014)

    NASA Astrophysics Data System (ADS)

    de Villiers, H. M.; Chrysostomou, A.; Thompson, M. A.; Ellingsen, S. P.; Urquhart, J. S.; Breen, S. L.; Burton, M. G.; Csengeri, T.; Ward-Thompson, D.

    2015-04-01

    The targets were observed with the JCMT, on the summit of Mauna Kea, Hawaii on seven nights between 2007 May 17 and 2008 July 22. Targets were mapped in the 13CO and C18O (J=3-2) transitions (330.6 and 329.3GHz), using the 16-receptor HARP. (5 data files).

  20. Fabrication and electrochemical performance of 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 microspheres by two-step spray-drying process

    NASA Astrophysics Data System (ADS)

    Son, Mun Yeong; Lee, Jung-Kul; Kang, Yun Chan

    2014-08-01

    0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures are prepared by a two-step spray-drying process. Precursor powders with hollow and porous structures prepared by the spray-drying process are post-treated at a low temperature of 400°C and then wet-milled to obtain a slurry with high stability. The slurry of the mixture of metal oxides is spray-dried to prepare precursor aggregate powders several microns in size. Post-treatment of these powders at high temperatures (>700°C) produces 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures and high crystallinity. The mean size and geometric standard deviation of the composite microspheres post-treated at 900°C are 4 μm and 1.38, respectively. Further, the initial charge capacities of the aggregated microspheres post-treated at 700, 800, 900, and 1000°C are 336, 349, 383, and 128 mA h g-1, respectively, and the corresponding discharge capacities are 286, 280, 302, and 77 mA h g-1, respectively. The discharge capacity of the composite microspheres post-treated at an optimum temperature of 900°C after 100 cycles is 242 mA h g-1, and the corresponding capacity retention is 80%.

  1. A systematic study of some promising electrolyte additives in Li[Ni1/3Mn1/3Co1/3]O2/graphite, Li[Ni0.5Mn0.3Co0.2]/graphite and Li[Ni0.6Mn0.2Co0.2]/graphite pouch cells

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Self, Julian; Nie, Mengyun; Glazier, Stephen; Wang, David Yaohui; Lin, Yong-Shou; Dahn, J. R.

    2015-12-01

    Li[Ni1/3Mn1/3Co1/3]O2/graphite, Li[Ni0.5Mn0.3Co0.2]O2/graphite and Li[Ni0.6Mn0.2Co0.2O2]/graphite pouch cells were examined with and without electrolyte additives using the ultra high precision charger at Dalhousie University, electrochemical impedance spectroscopy, gas evolution measurements and "cycle-store" tests. The electrolyte additives tested were vinylene carbonate (VC), prop-1-ene-1,3-sultone (PES), pyridine-boron trifluoride (PBF), 2% PES + 1% methylene methanedisulfonate (MMDS) + 1% tris(trimethylsilyl) phosphite (TTSPi) and 0.5% pyrazine di-boron trifluoride (PRZ) + 1% MMDS. The charge end-point capacity slippage, capacity fade, coulombic efficiency, impedance change during cycling, gas evolution and voltage drop during "cycle-store" testing were compared to gain an understanding of the effects of these promising electrolyte additives or additive combinations on the different types of pouch cells. It is hoped that this report can be used as a guide or reference for the wise choice of electrolyte additives in Li[Ni1/3Mn1/3Co1/3]O2/graphite, Li[Ni0.5Mn0.3Co0.2]O2/graphite and Li[Ni0.6Mn0.2Co0.2O2]/graphite pouch cells and also to show the shortcomings of particular positive electrode compositions.

  2. Fabrication and electrochemical performance of 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 microspheres by two-step spray-drying process

    PubMed Central

    Son, Mun Yeong; Lee, Jung-Kul; Kang, Yun Chan

    2014-01-01

    0.6Li2MnO3–0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures are prepared by a two-step spray-drying process. Precursor powders with hollow and porous structures prepared by the spray-drying process are post-treated at a low temperature of 400°C and then wet-milled to obtain a slurry with high stability. The slurry of the mixture of metal oxides is spray-dried to prepare precursor aggregate powders several microns in size. Post-treatment of these powders at high temperatures (>700°C) produces 0.6Li2MnO3–0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures and high crystallinity. The mean size and geometric standard deviation of the composite microspheres post-treated at 900°C are 4 μm and 1.38, respectively. Further, the initial charge capacities of the aggregated microspheres post-treated at 700, 800, 900, and 1000°C are 336, 349, 383, and 128 mA h g−1, respectively, and the corresponding discharge capacities are 286, 280, 302, and 77 mA h g−1, respectively. The discharge capacity of the composite microspheres post-treated at an optimum temperature of 900°C after 100 cycles is 242 mA h g−1, and the corresponding capacity retention is 80%. PMID:25168912

  3. Comparison of theoretical methods for the determination of the protonation and deprotonation energies of NH sub 3 , H sub 2 O, HF, PH sub 3 , H sub 2 S, HCl, and HCN

    SciTech Connect

    Del Bene, J.E. ); Shavitt, I. )

    1990-07-12

    The structures of the bases NH{sub 3}, H{sub 2}O, HF, PH{sub 3}, H{sub 2}S, HCl, and HCN and the corresponding protonated and deprotonated ions have been optimized by using second-order Moller-Plesset perturbation theory with the 6-31+G(d,p) basis. Basis set superposition errors for computed protonation and deprotonation energies of NH{sub 3} were evaluated for four different basis sets. Single-point calculations on all species were performed with the 6-31+G(2d,2p) basis using the following correlation methods: many-body (Moller-Plesset) perturbation theory at second (MP2), third (MP3), and fourth (MP4) order; the linearized coupled-cluster method (LCCM); the averaged coupled-pair functional (ACPF); configuration interaction with all single and double excitations (CISD); and CISD with the Davidson and the Pople corrections, all relative to a single-reference Hartree-Fock function.

  4. Ivabradine prolongs phase 3 of cardiac repolarization and blocks the hERG1 (KCNH2) current over a concentration-range overlapping with that required to block HCN4.

    PubMed

    Lees-Miller, James P; Guo, Jiqing; Wang, Yibo; Perissinotti, Laura L; Noskov, Sergei Y; Duff, Henry J

    2015-08-01

    In Europe, ivabradine has recently been approved to treat patients with angina who have intolerance to beta blockers and/or heart failure. Ivabradine is considered to act specifically on the sinoatrial node by inhibiting the If current (the funny current) to slow automaticity. However, in vitro studies show that ivabradine prolongs phase 3 repolarization in ventricular tissue. No episodes of Torsades de Pointes have been reported in randomized clinical studies. The objective of this study is to assess whether ivabradine blocked the hERG1 current. In the present study we discovered that ivabradine prolongs action potential and blocks the hERG current over a range of concentrations overlapping with those required to block HCN4. Ivabradine produced tonic, rather than use-dependent block. The mutation Y652A significantly suppressed pharmacologic block of hERG by ivabradine. Disruption of C-type inactivation also suppressed block of hERG1 by ivabradine. Molecular docking and molecular dynamics simulations indicate that ivabradine may access the inner cavity of the hERG1 via a lipophilic route and has a well-defined binding site in the closed state of the channel. Structural organization of the binding pockets for ivabradine is discussed. Ivabradine blocks hERG and prolongs action potential duration. Our study is potentially important because it indicates the need for active post marketing surveillance of ivabradine. Importantly, proarrhythmia of a number of other drugs has only been discovered during post marketing surveillance. PMID:25986146

  5. Satellite Boreal Measurements over Alaska and Canada During June-July 2004: Simultaneous Measurements of Upper Tropospheric CO, C2H6, HCN, CH3Cl, CH4, C2H2, CH2OH, HCOOH, OCS, and SF6 Mixing Ratios

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Dufour, Gaelle; Boone, Chris D.; Bernath, Peter F.; Chiou, Linda; Coheur, Pierre-Francois; Turquety, Solene; Clerbaux, Cathy

    2007-01-01

    Simultaneous ACE (Atmospheric Chemistry Experiment) upper tropospheric CO, C2H6, HCN, CH3Cl, CH4 , C2H2 , CH30H, HCOOH, and OCS measurements show plumes up to 185 ppbv (10 (exp -9) per unit volume) for CO, 1.36 p