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Sample records for 13c off-resonance rotating

  1. Rotational spectrum of 13C chloromethanes

    NASA Astrophysics Data System (ADS)

    Kania, Patrik; Stříteská, Lucie Nová; Šimečková, Marie; Musil, Peter; Kolesniková, Lucie; Koubek, Jindřich; Urban, Štěpán

    2008-11-01

    Rotational spectra of 13 carbon chloromethane isotopologues 13CH 335Cl and 13CH 337Cl with resolved hyperfine structures were measured in the spectral region from 50 GHz to 275 GHz. An estimated uncertainty of individual well developed lines was better than 5 kHz. Ground state molecular parameters B, DJ, DJK, HJ, HJK, HKJ, eQq, and CN were derived. Determination mainly of the hyperfine constants is significantly better than in previous studies.

  2. Investigation of intermolecular double-quantum off-resonance longitudinal relaxation in the tilted rotating frame

    NASA Astrophysics Data System (ADS)

    Cai, Honghao; Zheng, Bingwen; Ke, Hanping; Chen, Zhong

    2015-11-01

    A modified correlation spectroscopy revamped by asymmetric z-gradients echo detection (CRAZED) sequence was applied to investigate the behavior of intermolecular double-quantum longitudinal relaxation processes in the tilted rotating frame. Theoretical formalism based on dipolar field theory was presented in detail. Spectroscopic measurements and quantitative analysis demonstrated that the signal intensities and intermolecular double-quantum off-resonance longitudinal relaxation time in the rotating frame (T1ρ, DQC eff) are inversely correlated with the tilt angle (θ), while positively correlated with the effective frequency of spin-locking field (ωe). Magnetic resonance imaging experiments of an agarose phantom also prove the validity of the theoretical analysis and demonstrated the feasibility of imaging based on T1ρ, DQC eff . The rotating-frame double-quantum relaxation measurements are useful for probing slow-motion molecules and this study provides the guidance for optimization of the spin-lock experiments.

  3. Far off-resonance laser frequency stabilization using multipass cells in Faraday rotation spectroscopy.

    PubMed

    Quan, Wei; Li, Yang; Li, Rujie; Shang, Huining; Fang, Zishan; Qin, Jie; Wan, Shuangai

    2016-04-01

    We propose a far off-resonance laser frequency stabilization method by using multipass cells in Rb Faraday rotation spectroscopy. Based on the detuning equation, if multipass cells with several meters optical path length are used in the conventional Faraday spectroscopy, the detuning of the lock point can be extended much further from the alkali metal resonance. A plate beam splitter was used to generate two different Faraday signals at the same time. The transmitted optical path length was L=50  mm and the reflected optical path length was 2L=100  mm. When the optical path length doubled, the detuning of the lock points moved further away from the atomic resonance. The temperature dependence of the detuning of the lock point was also analyzed. A temperature-insensitive lock point was found near resonance when the cell temperature was between 110°C and 130°C. We achieved an rms fluctuation of 0.9 MHz/23 h at a detuning of 0.5 GHz. A frequency drift of 16 MHz/h at a detuning of -5.6  GHz and 4 MHz/h at a detuning of -5.2  GHz were also obtained for the transmitted and reflected light Faraday signal.

  4. Sub-Doppler Measurements of the Rotational Spectrum of (13)C(16)O.

    PubMed

    Klapper; Lewen; Gendriesch; Belov; Winnewisser

    2000-05-01

    The five lowest J rotational transitions of (13)C(16)O have been measured by saturation-dip spectroscopy to an accuracy of about 2 kHz, employing phase-stabilized backward-wave oscillators (BWOs). These highly precise measurements cover the transitions from J = 2 <-- 1 to J = 6 <-- 5 with frequencies ranging from 220 to 661 GHz. For each of the five observed rotational transitions, the narrow linewidths of the saturation dips (about 20 kHz) permitted the resolution of the hyperfine splitting for the first time. This splitting is caused by the (13)C-nuclear spin-rotation interaction yielding a value for the nuclear spin-rotation coupling constant of C(I)((13)C(16)O). If combined with the beam measurements (C(I)((13)C(16)O) = 32.63(10) kHz), a slight J-dependence of the spin-rotation coupling constant can be determined (C(J) = 30 +/- 13 Hz). In addition, we have measured in the Doppler-limited mode several higher J rotational line positions of (13)C(16)O up to 991 GHz with an accuracy of 5 kHz. The two line positions (J = 12 <-- 11 and J = 14 <-- 13) were recorded by multiplying BWO frequency with an accuracy of 100 kHz. The rotational transitions J = 17 <-- 16 and J = 18 <-- 17 were measured with an accuracy between 15 and 25 kHz by using the Cologne sideband spectrometer for terahertz applications COSSTA. Copyright 2000 Academic Press.

  5. Structural analysis of uniformly (13)C-labelled solids from selective angle measurements at rotational resonance.

    PubMed

    Patching, Simon G; Edwards, Rachel; Middleton, David A

    2009-08-01

    We demonstrate that individual H-C-C-H torsional angles in uniformly labelled organic solids can be estimated by selective excitation of (13)C double-quantum coherences under magic-angle spinning at rotational resonance. By adapting a straightforward one-dimensional experiment described earlier [T. Karlsson, M. Eden, H. Luhman, M.H. Levitt, J. Magn. Reson. 145 (2000) 95-107], a double-quantum filtered spectrum selective for Calpha and Cbeta of uniformly labelled L-[(13)C,(15)N]valine is obtained with 25% efficiency. The evolution of Calpha-Cbeta double-quantum coherence under the influence of the dipolar fields of bonded protons is monitored to provide a value of the Halpha-Calpha-Cbeta-Hbeta torsional angle that is consistent with the crystal structure. In addition, double-quantum filtration selective for C6 and C1' of uniformly labelled [(13)C,(15)N]uridine is achieved with 12% efficiency for a (13)C-(13)C distance of 2.5A, yielding a reliable estimate of the C6-H and C1'-H projection angle defining the relative orientations of the nucleoside pyrimidine and ribose rings. This procedure will be useful, in favourable cases, for structural analysis of fully labelled small molecules such as receptor ligands that are not readily synthesised with labels placed selectively at structurally diagnostic sites.

  6. Structural analysis of uniformly 13C-labelled solids from selective angle measurements at rotational resonance

    NASA Astrophysics Data System (ADS)

    Patching, Simon G.; Edwards, Rachel; Middleton, David A.

    2009-08-01

    We demonstrate that individual H-C-C-H torsional angles in uniformly labelled organic solids can be estimated by selective excitation of 13C double-quantum coherences under magic-angle spinning at rotational resonance. By adapting a straightforward one-dimensional experiment described earlier [T. Karlsson, M. Eden, H. Luhman, M.H. Levitt, J. Magn. Reson. 145 (2000) 95-107], a double-quantum filtered spectrum selective for Cα and Cβ of uniformly labelled L-[ 13C, 15N]valine is obtained with 25% efficiency. The evolution of Cα-Cβ double-quantum coherence under the influence of the dipolar fields of bonded protons is monitored to provide a value of the Hα-Cα-Cβ-Hβ torsional angle that is consistent with the crystal structure. In addition, double-quantum filtration selective for C6 and C1' of uniformly labelled [ 13C, 15N]uridine is achieved with 12% efficiency for a 13C- 13C distance of 2.5 Å, yielding a reliable estimate of the C6-H and C1'-H projection angle defining the relative orientations of the nucleoside pyrimidine and ribose rings. This procedure will be useful, in favourable cases, for structural analysis of fully labelled small molecules such as receptor ligands that are not readily synthesised with labels placed selectively at structurally diagnostic sites.

  7. VizieR Online Data Catalog: Rotational spectrum of 13C methylamine (Motiyenko+,

    NASA Astrophysics Data System (ADS)

    Motiyenko, R. A.; Margules, L.; Ilyushin, V. V.; Smirnov, I. A.; Alekseev, E. A.; Halfen, D. T.; Ziurys, L. M.

    2016-01-01

    Methylamine (CH3NH2) is a light molecule o interest, which has an intensive rotational spectrum that extends in the submillimeter wave range and far beyond, even at temperatures characteristic for the interstellar medium. It is likely for 13C isotopologue of methylamine to be identified in astronomical surveys, but there is no information available for the 13CH3NH2 millimeter and submillimeter wave spectra. In this context, to provide reliable predictions of 13CH3NH2 spectrum in millimeter and submillimeter wave ranges, we have studied rotational spectra of the 13C methylamine isotopologue in the frequency range from 48 to 945GHz. The spectrum of 13C methylamine was recorded using conventional absorption spectrometers in Lille and Kharkov. The analysis of the rotational spectrum of 13C methylamine in the ground vibrational state was performed on the basis of the group- theoretical high-barrier tunneling Hamiltonian that was developed for methylamine by Ohashi and Hougen. The available multiple observations of the parent methylamine species toward Sgr B2(N) at 1, 2, and 3mm using the Submillimeter Telescope and the 12 m antenna of the Arizona Radio Observatory were used to make a search for interstellar 13CH3NH2. In the recorded spectra, we have assigned 2721 rotational transitions that belong to the ground vibrational state of the 13CH3NH2. These measurements were fitted to the Hamiltonian model that uses 75 parameters to achieve an overall weighted rms deviation of 0.73. On the basis of these spectroscopic results, predictions of transition frequencies in the frequency range up to 950GHz with J<50 and Ka<20 are presented. The search for interstellar 13C methylamine in available observational data was not successful and therefore only an upper limit of 6.5x1014cm-2 can be derived for the column density of 13CH3NH2 toward Sgr B2(N), assuming the same source size, temperature, linewidth, and systemic velocity as for parent methylamine isotopic species. (2 data files).

  8. High-resolution FTIR analysis and rotational constants for the ν12 band of ethylene-1-13C (13C12CH4)

    NASA Astrophysics Data System (ADS)

    Gabona, M. G.; Tan, T. L.; Woo, J. Q.

    2014-11-01

    The Fourier transform infrared (FTIR) absorption spectrum of the ν12 fundamental band of ethylene-1-13C (or 13C12CH4) was recorded in the frequency range of 1350-1510 cm-1 with an unapodized resolution of 0.0063 cm-1. The upper state (ν12 = 1) and ground state rotational constants derived in the present analysis cover a wide wavenumber range and high J and Ka (J = 41 and Ka = 14). By assigning and fitting 1602 infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation, upper state (ν12 = 1) constants consisting of three rotational, five quartic and two sextic constants were more accurately determined. The root-mean-square deviation of the fit was 0.00030 cm-1. Ground state rotational constants were also improved from the fit of 808 ground state combination differences (GSCDs) with a root-mean-square deviation of 0.00032 cm-1. The unperturbed A-type ν12 band is centered at 1439.34612(2) cm-1. The inertial defect Δ of 0.05381(8) μÅ2 for the ground state has been derived using the ground state rotational constants obtained from this work.

  9. Tungsten monocarbide, WC: Pure rotational spectrum and 13C hyperfine interaction

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Steimle, Timothy C.

    2012-01-01

    The J = 1 → 2 pure rotational transitions in the X3Δ1(v = 0) state of 186W12C and 184W12C were recorded using a pump/probe microwave optical double resonance (PPMODR) technique and analyzed to give fine structure parameters. The field-free [17.6]2← X3Δ1 (1, 0) bands of the W13C isotopologues were recorded using laser induced fluorescence and analyzed to produce the 13C(I = 1/2) magnetic hyperfine parameter. Bonding in the [17.6]2(v = 1) and X3Δ1(v = 0) states is discussed and a comparison of the experimentally determined properties of the X3Δ1(v = 0) state with those predicted as a prelude to the electron electric dipole moment (eEDM) measurements [J. Lee, E. R. Meyer, R. Paudel, J. L. Bohn, and A. E. Leanhardt, J. Mod. Opt. 56, 2005 (2009), 10.1080/09500340903349930] is given.

  10. Combined off-resonance imaging and T2 relaxation in the rotating frame for positive contrast MR imaging of infection in a murine burn model

    PubMed Central

    Andronesi, Ovidiu C.; Mintzopoulos, Dionyssios; Righi, Valeria; Psychogios, Nikolaos; Kesarwani, Meenu; He, Jianxin; Yasuhara, Shingo; Dai, George; Rahme, Laurence G.; Tzika, Aria A.

    2010-01-01

    Purpose To develop novel magnetic resonance (MR) imaging methods to monitor accumulation of macrophages in inflammation and infection. Positive-contrast MR imaging provides an alternative to negative-contrast MRI, exploiting the chemical shift induced by ultra-small superparamagnetic iron-oxide (USPIO) nanoparticles to nearby water molecules. We introduce a novel combination of off-resonance (ORI) positive-contrast MRI and T2ρ relaxation in the rotating frame (ORI-T2ρ) for positive-contrast MR imaging of USPIO. Materials and Methods We tested ORI-T2ρ in phantoms and imaged in vivo the accumulation of USPIO-labeled macrophages at the infection site in a mouse model of burn trauma and infection with Pseudomonas aeruginosa (PA). PA infection is clinically important. The USPIO nanoparticles were injected directly in the animals in solution, and macrophage labeling occurred in vivo in the animal model. Results We observed a significant difference between ORI-T2ρ and ORI, which leads us to suggest that ORI-T2ρ is more sensitive in detecting USPIO signal. To this end, the ORI-T2ρ positive contrast method may prove to be of higher utility in future research. Conclusion Our results may have direct implications in the longitudinal monitoring of infection, and open perspectives for testing novel anti-infective compounds. PMID:21031524

  11. Analysis of the terahertz rotational spectrum of the three mono-13C ethyl cyanides (13C-CH3CH2CN)

    NASA Astrophysics Data System (ADS)

    Richard, C.; Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.

    2012-07-01

    Context. Millimeter- and submillimeter-wave spectra of regions such as the Orion molecular cloud show many rotational-torsional lines that are caused by the emission of complex organic molecules (COM). Previous laboratory investigations have been conducted for three isotopologues of ethyl cyanide up to 360 GHz, and subsequently, several hundred lines of the three isotopologues have been detected in Orion IRc2 using the IRAM 30 m radiotelescope. Aims: In this survey we present the analysis based on a Watson Hamiltonian for an asymmetric one-top rotor of the 13C-substituted ethyl cyanide 13CH3CH2CN, CH313CH2CN and CH3CH213CN in the frequency range 480-650 GHz and 780-990 GHz. Methods: The rotational spectra of the three species were measured with a submillimeter spectrometer (50-990 GHz) using solid-state sources. Results: A new set of spectroscopic parameters was determined from a least-squares fit procedure for each isotopologue. These parameters permit a new accurate prediction of rotational lines suitable for an astrophysical detection in the submillimeter wave range. Full Tables B.1-B.3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A135

  12. Exchange-dependent relaxation in the rotating frame for slow and intermediate exchange -- modeling off-resonant spin-lock and chemical exchange saturation transfer.

    PubMed

    Zaiss, Moritz; Bachert, Peter

    2013-05-01

    Chemical exchange observed by NMR saturation transfer (CEST) and spin-lock (SL) experiments provide an MRI contrast by indirect detection of exchanging protons. The determination of the relative concentrations and exchange rates is commonly achieved by numerical integration of the Bloch-McConnell equations. We derive an analytical solution of the Bloch-McConnell equations that describes the magnetization of coupled spin populations under radiofrequency irradiation. As CEST and off-resonant SL are equivalent, their steady-state magnetization and dynamics can be predicted by the same single eigenvalue: the longitudinal relaxation rate in the rotating frame R1ρ . For the case of slowly exchanging systems, e.g. amide protons, the saturation of the small proton pool is affected by transverse relaxation (R2b ). It turns out, that R2b is also significant for intermediate exchange, such as amine- or hydroxyl-exchange or paramagnetic CEST agents, if pools are only partially saturated. We propose a solution for R1ρ that includes R2 of the exchanging pool by extending existing approaches, and verify it by numerical simulations. With the appropriate projection factors, we obtain an analytical solution for CEST and SL for nonzero R2 of the exchanging pool, exchange rates in the range 1-10(4) Hz, B1 from 0.1 to 20 μT and arbitrary chemical shift differences between the exchanging pools, whilst considering the dilution by direct water saturation across the entire Z-spectra. This allows the optimization of irradiation parameters and the quantification of pH-dependent exchange rates and metabolite concentrations. In addition, we propose evaluation methods that correct for concomitant direct saturation effects. It is shown that existing theoretical treatments for CEST are special cases of this approach.

  13. Laboratory Precision Measurements of the Rotational Spectrum of 12C17O and 13C17O

    NASA Astrophysics Data System (ADS)

    Klapper, Gabriele; Surin, Leonid; Lewen, Frank; Müller, Holger S. P.; Pak, Igor; Winnewisser, Gisbert

    2003-01-01

    High-precision millimeter and submillimeter wave measurements were performed on two 17O isotopically substituted carbon monoxide species, i.e., 12C17O and 13C17O. Covering the frequency region from 100 GHz to 1 THz, the accuracy achievable is estimated to be +/-5 kHz in the Doppler-limited mode and +/-1 kHz for sub-Doppler-resolution measurements. From a weighted least-squares fit, the following molecular rotational parameters for 12C17O and 13C17O were obtained: for 12C17O,B0=56,179.99110(28)MHz,D0=174.330(6)kHzand for 13C17O,B0=53,644.7906(29)MHz,D0=158.918(19)kHzin both instances, the H0 values were kept fixed to IR data. The oxygen 17O nucleus exhibits a sizeable electric nuclear quadrupole moment, which has been measured for both isotopomers, i.e., eQq(12C17O)=4.298(44)MHz and eQq(13C17O)=4.355(182)MHz. The high precision of the Lamb dip measurements allowed us to observe additional small hyperfine effects caused by the magnetic moment of the 17O nucleus. These precision measurements allowed the determination of the nuclear spin-rotation constant CI(17O)=-31.60(72)Hz for 12C17O, solely from the Cologne data set. The highly precise transition frequencies reported here should warrant deep interstellar searches for the two molecules 12C17O and 13C17O. The latter has not been detected in space until very recently. On the basis of our laboratory data, we were able to report the discovery of 13C17O (by Bensch and coworkers) along with the observations of two additionalrare CO isotopomers including 12C17O and 12C18O toward core C of the ρ Ophiucus molecular cloud.

  14. Analysis of the Rotational Structure in the High-Resolution Infrared Spectrum of TRANS-HEXATRIENE-1-13C1

    NASA Astrophysics Data System (ADS)

    Craig, Norman C.; Tian, Hengfeng; Blake, Thomas A.

    2011-06-01

    Hexatriene-1-13C1 was synthesized by reaction of 2,4-pentadienal and (methyl-13C)-triphenylphosphonium iodide (Wittig reagent). The trans isomer was isolated by preparative gas chromatography, and the high-resolution (0.0015 Cm-1) infrared spectrum was recorded on a Bruker IFS 125HR instrument. The rotational structure in two C-type bands was analyzed. For this species the bands at 1010.7 and 893.740 Cm-1 yielded composite ground state rotational constants of A0 = 0.872820(1), B0 = 0.0435868(4), and C0 = 0.0415314(2) Cm-1. The ground state rotational constants for the 1-13C species were also predicted with Gaussian 03 software and the B3LYP/cc-pVTZ model. After scaling by the ratio of the observed and predicted ground state rotational constants for the normal species, the predicted ground state rotational constants for the 1-13C species agreed within 0.005 % with the observed values. Similar good agreement between observed and calculated values (0.016 %) was found for the three 13C species of the cis isomer. We conclude that ground state rotational constants for single heavy atom substitution can be calculated with adequate accuracy for use in determining semi-experimental equilibrium structures of small molecules. It will be unnecessary to synthesize the other two 13C species of trans-hexatriene. R. D. Suenram, B. H. Pate, A. Lesarri, J. L. Neill, S. Shipman, R. A. Holmes, M. C. Leyden, N. C. Craig J. Phys. Chem. A 113, 1864-1868 (2009).

  15. Carbon isotope compositions (δ(13) C) of leaf, wood and holocellulose differ among genotypes of poplar and between previous land uses in a short-rotation biomass plantation.

    PubMed

    Verlinden, M S; Fichot, R; Broeckx, L S; Vanholme, B; Boerjan, W; Ceulemans, R

    2015-01-01

    The efficiency of water use to produce biomass is a key trait in designing sustainable bioenergy-devoted systems. We characterized variations in the carbon isotope composition (δ(13) C) of leaves, current year wood and holocellulose (as proxies for water use efficiency, WUE) among six poplar genotypes in a short-rotation plantation. Values of δ(13) Cwood and δ(13) Cholocellulose were tightly and positively correlated, but the offset varied significantly among genotypes (0.79-1.01‰). Leaf phenology was strongly correlated with δ(13) C, and genotypes with a longer growing season showed a higher WUE. In contrast, traits related to growth and carbon uptake were poorly linked to δ(13) C. Trees growing on former pasture with higher N-availability displayed higher δ(13) C as compared with trees growing on former cropland. The positive relationships between δ(13) Cleaf and leaf N suggested that spatial variations in WUE over the plantation were mainly driven by an N-related effect on photosynthetic capacities. The very coherent genotype ranking obtained with δ(13) C in the different tree compartments has some practical outreach. Because WUE remains largely uncoupled from growth in poplar plantations, there is potential to identify genotypes with satisfactory growth and higher WUE.

  16. Rotational analysis of the Ångström system (B1Σ+-A1Π) in the rare 13C17O isotopologue

    NASA Astrophysics Data System (ADS)

    Hakalla, Rafał; Zachwieja, Mirosław

    2012-02-01

    Although yet unobserved in the very rare 13C17O isotopologue, the Ångström system (B1Σ+-A1Π) was obtained under high resolution as an emission spectrum using a conventional spectroscopic technique. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total, 192 transition wave numbers belonging to two bands (0-1 and 0-2) were precisely measured and rotationally analyzed. This method allowed us to determine the merged rotational constants B0 = 1.8131941(58) cm-1 and D0 = 5.5620(46) × 10-6 cm-1 and the individual molecular constant B1 = 1.471059(47) cm-1, D1 = 5.315(64) × 10-6 cm-1, B2 = 1.451762(13) cm-1, D2 = 7.812(16) × 10-6 cm-1 for the as yet unanalyzed 13C17O molecule B1Σ+ and A1Π states, respectively. The band origins σ of the Ångström system in the 13C17O molecule were also calculated. Numerous rotational perturbations observed in the A1Π state in 13C17O molecule have been identified and analyzed in detail. The suspected candidates responsible for these irregularities were indicated by means of a graph of the rovibronic levels of the neighboring states based on the estimated term value in the 13C17O molecule. The values of these perturbations have also been defined for both the e- and f-parity of the A1Π(v = 1 and 2) state. Simultaneously, the B1Σ+ state was observed to be quite regular up to the observed Jmax level.

  17. Optical hyperpolarization of 13C nuclear spins in nanodiamond ensembles

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2015-11-01

    Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear-spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

  18. Analysis of the Rotational Structure in the High-Resolution Infrared Spectrum of trans-Hexatriene-1-13C1; a Semiexperimental Equilibrium Structure for the C6 Backbone for trans-Hexatriene

    SciTech Connect

    Craig, Norman C.; Tian, Hengfeng; Blake, Thomas A.

    2012-03-29

    trans-Hexatriene-1-13C1 (tHTE-1-13C1) has been synthesized, and its high-resolution (0.0015 cm-1) infrared spectrum has been recorded. The rotational structure in the C-type bands for v26 at 1011 cm-1 and v30 at 894 cm-1 has been analyzed. To the 1458 ground state combination differences from these bands, ground state rotational constants were fitted to a Watson-type Hamiltonian to give A0 = 0.8728202(9), B0 = 0.0435868(4), and C0 = 0.0415314(2) cm-1. Upper state rotational constants for the v30 band were also fitted. Predictions of the ground state rotational constants for t-HTE-1-13C1 from a B3LYP/cc-pVTZ model with scale factors based on the normal species were in excellent agreement with observations. Similar good agreement was found between predicted and observed ground state rotational constants for the three 13C1 isotopologues of cis-hexatriene (cHTE), as determined from microwave spectroscopy. Equilibrium rotational constants for tHTE and its three 13C1 isotopologues, of which two were predicted, were used to find a semiexperimental equilibrium structure for the C6 backbone of tHTE. This structure shows increased structural effects of pi-electron delocalization in comparison with butadiene.

  19. Molecular mobility of lyophilized poly(vinylpyrrolidone) and methylcellulose as determined by the laboratory and rotating frame spin-lattice relaxation times of 1H and 13C.

    PubMed

    Yoshioka, Sumie; Aso, Yukio; Kojima, Shigeo

    2003-11-01

    Laboratory- and rotating- frame spin-lattice relaxation times (T(1) and T(1rho)) of (1)H and (13)C in lyophilized poly(vinylpyrrolidone) (PVP) and methylcellulose (MC) are determined to examine feasibility of using T(1) and T(1rho) as a measure of molecular motions on large time scales related to the storage stability of lyophilized formulations. The T(1rho) of proton and carbon was found to reflect the mobility of PVP and MC backbones, indicating that it is useful as a measure of large-time-scale molecular motions. In contrast to the T(1rho), the T(1) of proton measured in the same temperature range reflected the mobility of PVP and MC side chains. The T(1) of proton may be useful as a measure of local molecular motions on a smaller-time-scale, although the measurement is interfered by moisture under some conditions. The temperature dependence of T(1) and T(1rho) indicated that methylene in the MC molecule had much higher mobility than that in the dextran molecule, also indicated that methylene in the PVP side chain had a higher mobility than that in the MC side chain.

  20. Study of cross - relaxation and molecular dynamics in the solid 3-(trifluoromethyl) benzoic acid by solid state NMR off - resonance.

    PubMed

    Woźniak-Braszak, Aneta

    2017-02-01

    Molecular dynamics of the solid 3-(trifluoromethyl) benzoic acid containing proton (1)H and fluorine (19)F nuclei was explored by the solid-state NMR off - resonance technique. Contrary to the previous experiments the proton nuclei system I relaxed in the off - resonance effective field B→e while fluorine nuclei system S was saturated for short time in comparison to the relaxation time T1I. New cross - relaxation solid - state NMR off - resonance experiments were conducted on a homebuilt pulse spectrometer operating at the on-resonance frequency of 30.2MHz, at the off - resonance frequency varied between 30.2 and 30.6MHz for protons and at the frequency of 28.411MHz for fluorines, respectively. Based on the experimental data the dispersions of the proton off - resonance spin - lattice relaxation rate ρρ(I), the fluorine off - resonance spin - lattice relaxation rate ρρ(S) and the cross - relaxation rate σρ in the rotating frame were determined.

  1. Methodology for solid state NMR off-resonance study of molecular dynamics in heteronuclear systems.

    PubMed

    Jurga, Kazimierz; Woźniak-Braszak, Aneta; Baranowski, Mikołaj

    2015-10-01

    Methodology for the study of dynamics in heteronuclear systems in the laboratory frame was described in the previous paper [1]. Now the methodology for the study of molecular dynamics in the solid state heteronuclear systems in the rotating frame is presented. The solid state NMR off-resonance experiments were carried out on a homemade pulse spectrometer operating at the frequency of 30.2 MHz for protons. This spectrometer includes a specially designed probe which contains two independently tuned and electrically isolated coils installed in the coaxial position on the dewar. A unique probe design allows working at three slightly differing frequencies off and on resonance for protons and at the frequency of 28.411 MHz for fluorine nuclei with complete absence of their electrical interference. The probe allows simultaneously creating rf magnetic fields at off-resonance frequencies within the range of 30.2-30.6 MHz and at the frequency of 28.411 MHz. Presented heteronuclear cross-relaxation off-resonance experiments in the rotating frame provide information about molecular dynamics.

  2. Laboratory rotational spectrum of singly 13C-substituted dimethyl ether up to 1.5 THz and interstellar detection of 13CH_3O12CH_3 - a fruitful interplay between laboratory work and inter

    NASA Astrophysics Data System (ADS)

    Koerber, M.; Bisschop, S.; Endres, C.; Lewen, F.; Schlemmer, S.

    2011-05-01

    Dimethyl ether (CH_3OCH_3) is found in high abundance in star forming regions. However, the interstellar formation process of dimethyl ether still remains unclear up to now. In current gas-grain models gas-phase synthesis via self-methylation of methanol evaporating from grains is discussed in contrast to the surface reaction of CH_3 with successively hydrogenated CO (Garrod & Herbst 2006). An observational test for the formation mechanism has been proposed by Charnley et al. (2004) making use of the 13C fractionation into CO at low temperatures on grains: Comparing the 12C/13C ratio of molecules to the 12CO/13CO ratio allows to distinguish between formation from CO on cold grains and pure gas-phase formation routes. The isotopic ratio of species like dimethyl ether thus can be used as a tracer of the chemical evolution of the observed region. Due to its two methyl groups undergoing large amplitude motions and a relatively strong dipole moment of μ = 1.302 D it shows a strong and dense complex spectrum all over the terahertz region relevant for Herschel and ALMA observations. Accurate transition frequencies are needed to interpret the astronomical spectra. For the main isotopologue extensive data are now available (Endres et al. 2009). However, due to the greatly improved sensitivity of the new observatories isotopic species of abundant molecules like dimethyl ether are appearing in the spectra as well. In this work we present laboratory measurements of singly 13C-substituted dimethyl ether (13CH_3O12CH_3) up to 1.5 THz. More than 1700 transitions of 13CH_3O12CH_3 with rotational quantum numbers up to J = 53 and K = 25 have been analyzed. Based on the laboratory measurements singly 13C-substituted dimethyl ether has been detected for the first time in the spectrum of G327.3-0.6 (Bisschop et al. in prep.) and a preliminary value for the 12C/13C abundance ratio has been determined.

  3. 13C(16)O(2): Global Treatment of Vibrational-Rotational Spectra and First Observation of the 2nu(1) + 5nu(3) and nu(1) + 2nu(2) + 5nu(3) Absorption Bands.

    PubMed

    Tashkun; Perevalov; Teffo; Lecoutre; Huet; Campargue; Bailly; Esplin

    2000-04-01

    The effective operator approach is applied to the calculation of both line positions and line intensities of the (13)C(16)O(2) molecule. About 11 000 observed line positions of (13)C(16)O(2) selected from the literature have been used to derive 84 parameters of a reduced effective Hamiltonian globally describing all known vibrational-rotational energy levels in the ground electronic state. The standard deviation of the fit is 0.0015 cm(-1). The eigenfunctions of this effective Hamiltonian have then been used in fittings of parameters of an effective dipole-moment operator to more than 600 observed line intensities of the cold and hot bands covering the nu(2) and 3nu(2) regions. The standard deviations of the fits are 3.2 and 12.0% for these regions, respectively. The quality of the fittings and the extrapolation properties of the fitted parameters are discussed. A comparison of calculated line parameters with those provided by the HITRAN database is given. Finally, the first observations of the 2nu(1) + 5nu(3) and nu(1) + 2nu(2) + 5nu(3) absorption bands by means of photoacoustic spectroscopy (PAS) is presented. The deviations of predicted line positions from observed ones is found to be less than 0.1 cm(-1), and most of them lie within the experimental accuracy (0.007 cm(-1)) once the observed line positions are included in the global fit. Copyright 2000 Academic Press.

  4. 13C NMR of tunnelling methyl groups

    NASA Astrophysics Data System (ADS)

    Detken, A.

    The dipolar interactions between the protons and the central 13C nucleus of a 13CH3 group are used to study rotational tunnelling and incoherent dynamics of such groups in molecular solids. Single-crystal 13C NMR spectra are derived for arbitrary values of the tunnel frequency upsilon t. Similarities to ESR and 2H NMR are pointed out. The method is applied to three different materials. In the hydroquinone/acetonitrile clathrate, the unique features in the 13C NMR spectra which arise from tunnelling with a tunnel frequency that is much larger than the dipolar coupling between the methyl protons and the 13C nucleus are demonstrated, and the effects of incoherent dynamics are studied. The broadening of the 13C resonances is related to the width of the quasi-elastic line in neutron scattering. Selective magnetization transfer experiments for studying slow incoherent dynamics are proposed. For the strongly hindered methyl groups of L-alanine, an upper limit for upsilon is derived from the 13C NMR spectrum. In aspirinTM (acetylsalicylic acid), incoherent reorientations dominate the spectra down to the lowest temperatures studied; their rate apparently increases with decreasing temperature below 25K.

  5. 13C metabolic flux analysis.

    PubMed

    Wiechert, W

    2001-07-01

    Metabolic flux analysis using 13C-labeled substrates has become an important tool in metabolic engineering. It allows the detailed quantification of all intracellular fluxes in the central metabolism of a microorganism. The method has strongly evolved in recent years by the introduction of new experimental procedures, measurement techniques, and mathematical data evaluation methods. Many of these improvements require advanced skills in the application of nuclear magnetic resonance and mass spectrometry techniques on the one hand and computational and statistical experience on the other hand. This minireview summarizes these recent developments and sketches the major practical problems. An outlook to possible future developments concludes the text.

  6. Contribution of off-resonant states to the phase noise of quantum dot lasers.

    PubMed

    Wang, Cheng; Zhuang, Jun-Ping; Grillot, Frédéric; Chan, Sze-Chun

    2016-12-26

    The phase noise of quantum dot lasers is investigated theoretically by coupling the Langevin noise sources into the rate equations. The off-resonant populations in the excited state and in the carrier reservoir contribute to the phase noise of ground-state emission lasers through the phase-amplitude coupling effect. This effect arises from the optical-noise induced carrier fluctuations in the off-resonant states. In addition, the phase noise has low sensitivity to the carrier scattering rates.

  7. Synthesis of exemestane labelled with (13)C.

    PubMed

    Fontana, Erminia; Pignatti, Alberto; Giribone, Danilo; Di Salle, Enrico

    2008-08-01

    The synthesis of exemestane Aromasin, an irreversible steroidal aromatase inhibitor, specifically labelled with (13)C is reported. The preparation of [(13)C(3)]exemestane was achieved according to an eight-step procedure starting from the commercially available testosterone.

  8. (13)C NMR Metabolomics: INADEQUATE Network Analysis.

    PubMed

    Clendinen, Chaevien S; Pasquel, Christian; Ajredini, Ramadan; Edison, Arthur S

    2015-06-02

    The many advantages of (13)C NMR are often overshadowed by its intrinsically low sensitivity. Given that carbon makes up the backbone of most biologically relevant molecules, (13)C NMR offers a straightforward measurement of these compounds. Two-dimensional (13)C-(13)C correlation experiments like INADEQUATE (incredible natural abundance double quantum transfer experiment) are ideal for the structural elucidation of natural products and have great but untapped potential for metabolomics analysis. We demonstrate a new and semiautomated approach called INETA (INADEQUATE network analysis) for the untargeted analysis of INADEQUATE data sets using an in silico INADEQUATE database. We demonstrate this approach using isotopically labeled Caenorhabditis elegans mixtures.

  9. Characterization of the restricted rotation of the dimethyl groups in chemically N-terminal 13C-labeled antifreeze glycoproteins: A temperature-dependent study in water to ice through the supercooled state

    NASA Astrophysics Data System (ADS)

    Krishnan, V. V.; Lau, Edmond Y.; Tsvetkova, Nelly M.; Feeney, Robert E.; Fink, William H.; Yeh, Yin

    2005-07-01

    Site-specific chemical modification, especially with isotopically enriched groups, allows one to study the structure and dynamics of proteins for which uniform enrichment is difficult. When the N-terminal alanine in antifreeze glycoprotein (AFGP) is replaced with an N,N-dimethyl alanine the methyl groups show signatures of slow rotation about the C-N bond. In order to separate the local dynamics of the N-terminus from the overall protein dynamics, we present a complete characterization of this dynamics. Temperature-dependent nuclear magnetic-resonance experiments from room temperature to subzero temperatures, including the supercooled state and in the presence of ice, are presented. Quantum chemical calculations are also performed on a localized N-terminus of the AFGP. Our results show that in the solution state at room temperature and in the super cooled regime, the dimethyl groups undergo a slow, restricted rotation with an unequal distribution of population between two major conformations. At lower temperatures in the presence of ice, the dynamics become much more complex due to freezing out of several conformational states. Based on these results, we conclude that the segmental dynamics of the N-terminus are local to the first residue and do not affect the overall dynamics of the protein.

  10. New guidelines for δ13C measurements

    USGS Publications Warehouse

    Coplen, Tyler B.; Brand, Willi A.; Gehre, Matthias; Groning, Manfred; Meijer, Harro A. J.; Toman, Blaza; Verkouteren, R. Michael

    2006-01-01

    Consistency of δ13C measurements can be improved 39−47% by anchoring the δ13C scale with two isotopic reference materials differing substantially in 13C/12C. It is recommended thatδ13C values of both organic and inorganic materials be measured and expressed relative to VPDB (Vienna Peedee belemnite) on a scale normalized by assigning consensus values of −46.6‰ to L-SVEC lithium carbonate and +1.95‰ to NBS 19 calcium carbonate. Uncertainties of other reference material values on this scale are improved by factors up to two or more, and the values of some have been notably shifted:  the δ13C of NBS 22 oil is −30.03%.

  11. Multiple locations of peptides in the hydrocarbon core of gel-phase membranes revealed by peptide (13)C to lipid (2)H rotational-echo double-resonance solid-state nuclear magnetic resonance.

    PubMed

    Xie, Li; Jia, Lihui; Liang, Shuang; Weliky, David P

    2015-01-27

    Membrane locations of peptides and proteins are often critical to their functions. Solid-state rotational-echo double-resonance (REDOR) nuclear magnetic resonance is applied to probe the locations of two peptides via peptide (13)CO to lipid (2)H distance measurements. The peptides are KALP, an α-helical membrane-spanning peptide, and HFP, the β-sheet N-terminal fusion peptide of the HIV gp41 fusion protein that plays an important role in HIV-host cell membrane fusion. Both peptides are shown to have at least two distinct locations within the hydrocarbon core of gel-phase membranes. The multiple locations are attributed to snorkeling of lysine side chains for KALP and to the distribution of antiparallel β-sheet registries for HFP. The relative population of each location is also quantitated. To the best of our knowledge, this is the first clear experimental support of multiple peptide locations within the membrane hydrocarbon core. These data are for gel-phase membranes, but the approach should work for liquid-ordered membranes containing cholesterol and may be applicable to liquid-disordered membranes with appropriate additional analysis to take into account protein and lipid motion. This paper also describes the methodological development of (13)CO-(2)H REDOR using the lyophilized I4 peptide that is α-helical and (13)CO-labeled at A9 and (2)Hα-labeled at A8. The I4 spins are well-approximated as an ensemble of isolated (13)CO-(2)H spin pairs each separated by 5.0 Å with a 37 Hz dipolar coupling. A pulse sequence with rectangular 100 kHz (2)H π pulses results in rapid and extensive buildup of REDOR (ΔS/S0) with a dephasing time (τ). The buildup is well-fit by a simple exponential function with a rate of 24 Hz and an extent close to 1. These parameter values reflect nonradiative transitions between the (2)H spin states during the dephasing period. Each spin pair spends approximately two-thirds of its time in the (13)CO-(2)H (m = ±1) states and

  12. Millimeter and submillimeter wave spectra of 13C methylamine

    NASA Astrophysics Data System (ADS)

    Motiyenko, R. A.; Margulès, L.; Ilyushin, V. V.; Smirnov, I. A.; Alekseev, E. A.; Halfen, D. T.; Ziurys, L. M.

    2016-03-01

    Context. Methylamine (CH3NH2) is a light molecule of astrophysical interest, which has an intensive rotational spectrum that extends in the submillimeter wave range and far beyond, even at temperatures characteristic for the interstellar medium. It is likely for 13C isotopologue of methylamine to be identified in astronomical surveys, but there is no information available for the 13CH3NH2 millimeter and submillimeter wave spectra. Aims: In this context, to provide reliable predictions of 13CH3NH2 spectrum in millimeter and submillimeter wave ranges, we have studied rotational spectra of the 13C methylamine isotopologue in the frequency range from 48 to 945 GHz. Methods: The spectrum of 13C methylamine was recorded using conventional absorption spectrometers. The analysis of the rotational spectrum of 13C methylamine in the ground vibrational state was performed on the basis of the group-theoretical high-barrier tunneling Hamiltonian that was developed for methylamine. The available multiple observations of the parent methylamine species toward Sgr B2(N) at 1, 2, and 3 mm using the Submillimeter Telescope and the 12 m antenna of the Arizona Radio Observatory were used to make a search for interstellar 13CH3NH2. Results: In the recorded spectra, we have assigned 2721 rotational transitions that belong to the ground vibrational state of the 13CH3NH2. These measurements were fitted to the Hamiltonian model that uses 75 parameters to achieve an overall weighted rms deviation of 0.73. On the basis of these spectroscopic results, predictions of transition frequencies in the frequency range up to 950 GHz with J ≤ 50 and Ka ≤ 20 are presented. The search for interstellar 13C methylamine in available observational data was not successful and therefore only an upper limit of 6.5 × 1014 cm-2 can be derived for the column density of 13CH3NH2 toward Sgr B2(N), assuming the same source size, temperature, linewidth, and systemic velocity as for parent methylamine isotopic

  13. Far off-resonant coupling between photonic crystal microcavity and single quantum dot with resonant excitation

    SciTech Connect

    Banihashemi, Mehdi; Ahmadi, Vahid; Nakamura, Tatsuya; Kojima, Takanori; Kojima, Kazunobu; Noda, Susumu

    2013-12-16

    In this paper, we experimentally demonstrate that with sub-nanowatt coherent s-shell excitation of a single InAs quantum dot, off-resonant coupling of 4.1 nm is possible between L3 photonic crystal microcavity and the quantum dot at 50 K. This resonant excitation reduces strongly the effect of surrounding charges to quantum dot, multiexciton complexes and pure dephasing. It seems that this far off-resonant coupling is the result of increased number of acoustical phonons due to high operating temperature of 50 K. The 4.1 nm detuning is the largest amount for this kind of coupling.

  14. Loading and compressing cesium atoms in a very far-off- resonant light trap

    NASA Astrophysics Data System (ADS)

    Depue, Marshall Thomas

    An experiment is described in which 3 × 107 Cs atoms are loaded into a 400 μm crossed beam far-off-resonant trap (FORT) that is only 2.5 μK deep. A high density sample is prepared in a magneto-optic trap (MOT), cooled in a 3D far-off-resonant lattice (FORL), optically pumped into the lowest energy state, adiabatically released from the FORL, magnetically levitated, and transferred to the final FORT trap with a phase space density of 10-3. Spontaneous emission in the FORT is negligible, and the atoms can be compressed in the FORT to a spatial density of higher than 1014 cm-3. Evaporative cooling under these conditions can proceed rapidly. The atoms are monitored with a high intensity fluorescent imaging technique that is well suited to providing accurate number and density measurements for optically thick samples.

  15. Shaping interactions between polar molecules with far-off-resonant light

    NASA Astrophysics Data System (ADS)

    Lemeshko, Mikhail

    2011-05-01

    We show that dressing polar molecules with a far-off-resonant optical field leads to new types of intermolecular potentials, which undergo a crossover from the inverse power to oscillating behavior depending on the intermolecular distance, and whose parameters can be tuned by varying the laser intensity and wavelength. We present analytic expressions for the potential energy surfaces, thereby providing direct access to the parameters of an optical field required to design intermolecular interactions experimentally.

  16. Shaping interactions between polar molecules with far-off-resonant light

    SciTech Connect

    Lemeshko, Mikhail

    2011-05-15

    We show that dressing polar molecules with a far-off-resonant optical field leads to new types of intermolecular potentials, which undergo a crossover from the inverse power to oscillating behavior depending on the intermolecular distance, and whose parameters can be tuned by varying the laser intensity and wavelength. We present analytic expressions for the potential energy surfaces, thereby providing direct access to the parameters of an optical field required to design intermolecular interactions experimentally.

  17. Application of 13C-labeling and 13C-13C COSY NMR experiments in the structure determination of a microbial natural product.

    PubMed

    Kwon, Yun; Park, Sunghyouk; Shin, Jongheon; Oh, Dong-Chan

    2014-08-01

    The elucidation of the structures of complex natural products bearing many quaternary carbons remains challenging, even in this advanced spectroscopic era. (13)C-(13)C COSY NMR spectroscopy shows direct couplings between (13)C and (13)C, which comprise the backbone of a natural product. Thus, this type of experiment is particularly useful for natural products bearing consecutive quaternary carbons. However, the low sensitivity of (13)C-based NMR experiments, due to the low natural abundance of the (13)C nucleus, is problematic when applying these techniques. Our efforts in the (13)C labeling of a microbial natural product, cyclopiazonic acid (1), by feeding (13)C-labeled glucose to the fungal culture, enabled us to acquire (13)C-(13)C COSY NMR spectra on a milligram scale that clearly show the carbon backbone of the compound. This is the first application of (13)C-(13)C COSY NMR experiments for a natural product. The results suggest that (13)C-(13)C COSY NMR spectroscopy can be routinely used for the structure determination of microbial natural products by (13)C-enrichment of a compound with (13)C-glucose.

  18. Comparative absorption of [13C]glucose and [13C]lactose by premature infants.

    PubMed

    Murray, R D; Boutton, T W; Klein, P D; Gilbert, M; Paule, C L; MacLean, W C

    1990-01-01

    Oxidation of orally administered [13C]glucose and [13C]lactose and fecal recovery of malabsorbed substrates were determined in two groups of premature infants. Eighteen studies were performed with six infants at Johns Hopkins Hospital (JHH); 24 studies were performed with nine infants at Columbus Children's Hospital (CCH). The two groups differed in that JHH infants had shorter gestations but were older when studied. Fecal 13C loss after [13C]glucose administration did not differ between the two groups. Compared with glucose, the metabolism of lactose appeared to involve more malabsorption and colonic fermentation in JHH infants than in CCH infants and resulted in higher fecal losses of substrate carbon. Maturation appeared to involve increased proximal intestinal absorption and greater retention of absorbed carbohydrate. Simultaneous absorption of substrate from the small and large intestine may limit the usefulness of breath tests for 13C in the premature infant.

  19. Functional MR imaging in the awake monkey: effects of motion on dynamic off-resonance and processing strategies.

    PubMed

    Pfeuffer, Josef; Shmuel, Amir; Keliris, Georgios A; Steudel, Thomas; Merkle, Hellmut; Logothetis, Nikos K

    2007-07-01

    Functional MR imaging of the alert, behaving monkey is being used more and more often to detect activation patterns and guide electrophysiological research investigating the neural basis of behavior. Several labs have reported fMRI data from the awake monkey, but none of them has studied and systematically corrected the effects of monkeys' motion on fMRI time series. In this study, a significant refinement of acquisition and correction strategies is reported that can be used to minimize magnetic susceptibility artifacts induced by respiration and by jaw and body movement. Real-time acquisition of sensor signals (e.g., signals induced by jaw and body movement) and MR navigator data were combined to optimize fMRI signal-correction strategies. Within trials, the artifact-induced off-resonance changes were small and mainly reflected the effects of respiration; between trials, movements caused major changes of global frequency and shim (>20 Hz/cm). Several methods were used to assess the stability of the fMRI series: k-space analysis ('dynamic intensity and off-resonance changes in k-space', dubbed DICK and DORK) and image analysis using a Laplace operator and a center-of-mass metric. The variability between trials made it essential to correct for inter-trial variations. On the other hand, images were sufficiently stable with our approach to perform fMRI evaluations on single trials before averaging of trials. Different motion correction strategies were compared: DORK, McFLIRT (rigid body model with three translations and three rotations) and 2D image alignment based on a center-of-mass detection (in-plane translation). The latter yielded the best results and proved to be fast and robust for intra- and inter-trial alignment. Finally, fMRI in the behaving monkey was tested for spatial and temporal reproducibility on a trial-to-trial basis. Highly activated voxels also displayed good reproducibility between trials. On average, the BOLD amplitude response to a short 3-s

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

    DOEpatents

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

    2004-03-30

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

  1. Correcting for Incomplete Saturation and Off-Resonance Effects in Multiple-Site Saturation-Transfer Kinetic Measurements

    NASA Astrophysics Data System (ADS)

    Kingsley, Peter B.; Monahan, W. Gordon

    2000-09-01

    The effects of incomplete saturation and off-resonance irradiation on nuclear magnetic resonance saturation-transfer measurements of three-site chemical-exchange rates are discussed. A new method that uses double-saturation measurements is compared with two published methods, one that uses single-saturation measurements and one that uses a single-saturation measurement and a double-saturation measurement. Several formulas are compared for measuring the exchange rate constant kDE for exchange from a detected spin D to an exchanging spin E in the presence of exchange from spin D to a competing spin C. For each method, formulas are derived with corrections for incomplete saturation or off-resonance effects, with both corrections, and with neither correction. Exact formulas are available for three exchanging sites with incomplete saturation if there are no off-resonance effects. Off-resonance corrections are imperfect even with complete saturation.

  2. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates

    NASA Astrophysics Data System (ADS)

    Azurmendi, Hugo F.; Freedberg, Darón I.

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for 1DCC determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a 13C-13C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield 1JCC and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for JHH determinations, but adapted and extended to applications where, like in sugars, large one-bond 13C-13C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and oriented phases are very

  3. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates.

    PubMed

    Azurmendi, Hugo F; Freedberg, Darón I

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for (1)D(CC) determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a (13)C-(13)C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield (1)J(CC) and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for J(HH) determinations, but adapted and extended to applications where, like in sugars, large one-bond (13)C-(13)C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and

  4. Quantum state transfer and conditional phase gate via off-resonant quantum Zeno dynamics

    NASA Astrophysics Data System (ADS)

    Su, Wan-Jun; Yang, Zhen-Biao; Wu, Huai-Zhi

    2017-01-01

    We propose a scheme to realize the quantum state transfer (QST) and conditional phase gate (CPG) between two qubits (acted by nitrogen-vacancy (NV) centers) based on off-resonant quantum Zeno dynamics. We also consider the entanglement dynamics of two qubits in this system. Since no cavity photons or excited levels of the NV center is populated during the whole process, the scheme is immune to the decay of cavity and spontaneous emission of the NV center. The strictly numerical simulation shows that the fidelities of QST and CPG are high even in the presence of realistic imperfections.

  5. Weyl semimetal generated from Dirac semimetal using off-resonant light

    NASA Astrophysics Data System (ADS)

    Cao, Jie; Qi, Fenghua; Tang, Chi Pui

    2016-12-01

    We propose a simple realization of a three-dimensional Weyl semimetal phase using off-resonant circularly polarized light in the three dimensional Dirac semimetals. Using both analytical and numerical methods, we show that a fourfold degenerate Dirac node can be further evolved into two Weyl nodes in the context of low energy Hamiltonian. The distance between the two Weyl nodes in momentum space can be controlled by the intensity and frequency of the light. Meanwhile, because this distance is proportional to the relatively large Fermi velocity, the typical character of the Weyl semimetal, such as surface Fermi arc, can be observed obviously.

  6. Input impedance matching of acoustic transducers operating at off-resonant frequencies.

    PubMed

    Son, Kyu Tak; Lee, Chin C

    2010-12-01

    The input impedance matching technique of acoustic transducers at off-resonant frequencies is reported. It uses an inherent impedance property of transducers and thus does not need an external electric matching circuit or extra acoustic matching section. The input electrical equivalent circuit includes a radiation component and a dielectric capacitor. The radiation component consists of a radiation resistance and a radiation reactance. The total reactance is the sum of the radiation reactance and the dielectric capacitive reactance. This reactance becomes zero at two frequencies where the impedance is real. The transducer size can be properly chosen so that the impedance at one of the zero-crossing frequencies is close to 50 Ω, the output impedance of signal generators. At this off-resonant operating frequency, the reflection coefficient of the transducer is minimized without using any matching circuit. Other than the size, the impedance can also be fine tuned by adjusting the thickness of material that bonds the transducer plate to the substrates. The acoustic impedance of the substrate and that of the bonding material can also be used as design elements in the transducer structure to achieve better transducer matching. Lead titanate piezoelectric plates were bonded on Lucite, liquid crystal polymer (LCP), and bismuth (Bi) substrates to produce various transducer structures. Their input impedance was simulated using a transducer model and compared with measured values to illustrate the matching principle.

  7. Collisional activation of ions by off-resonance irradiation in ion cyclotron resonance spectrometry

    NASA Astrophysics Data System (ADS)

    Shin, Seung Koo; Han, Seung-Jin; Seo, Jongcheol

    2009-06-01

    Collisional activation of ions in the ion cyclotron resonance (ICR) cell by short off-resonance burst irradiation (ORBI) was studied by time-resolved photodissociation of the meta-bromotoluene radical cation. Off-resonance chirp or single-frequency burst was applied for 2 ms to the probe ion in the presence of Ar buffer gas. The amount of internal energy imparted to the probe ion by collision under ORBI was precisely determined by time-resolved photodissociation spectroscopy. The rate of unimolecular dissociation of the probe ion following the photolysis at 532 nm was measured by monitoring the real-time appearance of the C7H7+ product ion. The internal energy of the probe ion was extracted from the known rate-energy curve. To help understand the collisional activation of an ion under ORBI, we simulated the radial trajectory of the ion using Green's method. The calculated radial kinetic energy was converted to the collision energy in the center-of-mass frame, and the collision frequency was estimated by using a reactive hard-sphere collision model with an ion-induced dipole potential. Both experiments and trajectory simulations suggest that chirp irradiation leads to less collisional activation of ions than other waveforms.

  8. Optoacoustic 13C-breath test analyzer

    NASA Astrophysics Data System (ADS)

    Harde, Hermann; Helmrich, Günther; Wolff, Marcus

    2010-02-01

    The composition and concentration of exhaled volatile gases reflects the physical ability of a patient. Therefore, a breath analysis allows to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that employs a compact and simple set-up based on photoacoustic spectroscopy. It consists of two identical photoacoustic cells containing two breath samples, one taken before and one after capturing an isotope-marked substrate, where the most common isotope 12C is replaced to a large extent by 13C. The analyzer measures simultaneously the relative CO2 isotopologue concentrations in both samples by exciting the molecules on specially selected absorption lines with a semiconductor laser operating at a wavelength of 2.744 μm. For a reliable diagnosis changes of the 13CO2 concentration of 1% in the exhaled breath have to be detected at a concentration level of this isotope in the breath of about 500 ppm.

  9. Motion-Insensitive Localized 13C Spectroscopy Using Cyclic and Slice-Selective J Cross Polarization

    NASA Astrophysics Data System (ADS)

    Kunze, C.; Kimmich, R.

    Several new methods are proposed for the sensitive localized detection of 13C nuclei on the basis of cyclic and slice-selective J cross polarization in 13C 1H x spin systems. The 13C nuclei are detected either directly after the amplitude is enhanced by polarization transfer in the rotating frame or, preferably, indirectly by heteronuclear editing of signals of the 1H nuclei coupled to 13C. In the latter case, the sensitivity corresponds to that of 1H rather than to that of 13C resonance. Test experiments are reported. In vitro applications to a hen egg and a fresh porcine shank prove the applicability of the methods to biological objects with 13C in natural abundance. A particular advantage of the new rotating-frame methods over laboratory-frame techniques serving the same purpose is the insensitivity to motions of the object. This is demonstrated by experiments with a moving sample. Hartmann/Hahn mismatch can be compensated using the MOIST modification. The time-averaged absorbed radiofrequency power per kilogram body weight was estimated on the basis of a model for surface power absorption. The result lies well below the standard safety limits for clinical applications.

  10. Improved ground state and ν12 = 1 state rovibrational constants for ethylene-13C2 (13C2H4)

    NASA Astrophysics Data System (ADS)

    Gabona, M. G.; Tan, T. L.

    2014-05-01

    The Fourier transform infrared (FTIR) absorption spectrum of the ν12 fundamental band of ethylene-13C2 (13C2H4) was recorded in the frequency range of 1350-1550 cm-1 with unapodized resolution of 0.0063 cm-1. Improved upper state (ν12 = 1) rovibrational constants consisting of three rotational, five quartic and five sextic constants were derived by assigning and fitting 1731 infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation. The root-mean-square deviation of the fit was 0.00030 cm-1. More higher-order upper state (ν12 = 1) constant were derived in the present analysis than previously reported. Improved ground state rovibrational constants were also determined from the fit of 1104 ground state combination differences (GSCD) with a root-mean-square deviation of 0.00029 cm-1. The A-type ν12 band centered at 1436.65409 ± 0.00002 cm-1 has a calculated inertial defect Δ12 is 0.242896 ± 0.000007 μÅ2. No indications of perturbation were found in the analysis of the band.

  11. Towards hyperpolarized 13C-succinate imaging of brain cancer

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Pratip; Chekmenev, Eduard Y.; Perman, William H.; Harris, Kent C.; Lin, Alexander P.; Norton, Valerie A.; Tan, Chou T.; Ross, Brian D.; Weitekamp, Daniel P.

    2007-05-01

    We describe a novel 13C enriched precursor molecule, sodium 1- 13C acetylenedicarboxylate, which after hydrogenation by PASADENA (Parahydrogen and Synthesis Allows Dramatically Enhanced Nuclear Alignment) under controlled experimental conditions, becomes hyperpolarized 13C sodium succinate. Fast in vivo 3D FIESTA MR imaging demonstrated that, following carotid arterial injection, the hyperpolarized 13C-succinate appeared in the head and cerebral circulation of normal and tumor-bearing rats. At this time, no in vivo hyperpolarized signal has been localized to normal brain or brain tumor. On the other hand, ex vivo samples of brain harvested from rats bearing a 9L brain tumor, 1 h or more following in vivo carotid injection of hyperpolarized 13C sodium succinate, contained significant concentrations of the injected substrate, 13C sodium succinate, together with 13C maleate and succinate metabolites 1- 13C-glutamate, 5- 13C-glutamate, 1- 13C-glutamine and 5- 13C-glutamine. The 13C substrates and products were below the limits of NMR detection in ex vivo samples of normal brain consistent with an intact blood-brain barrier. These ex vivo results indicate that hyperpolarized 13C sodium succinate may become a useful tool for rapid in vivo identification of brain tumors, providing novel biomarkers in 13C MR spectral-spatial images.

  12. Coherent control of atomic excitation using off-resonant strong few-cycle pulses

    SciTech Connect

    Jha, Pankaj K.; Eleuch, Hichem; Rostovtsev, Yuri V.

    2010-10-15

    We study the dynamics of a two-level system driven by an off-resonance few-cycle pulse which has a phase jump {phi} at t=t{sub 0}, in contrast to many-cycle pulses, under the nonrotating-wave approximation (NRWA). We give a closed form analytical solution for the evolution of the probability amplitude |C{sub a}(t)| for the upper level. Using the appropriate pulse parameters like the phase jump {phi}, jump time t{sub 0}, pulse width {tau}, frequency {nu}, and Rabi frequency {Omega}{sub 0} the population transfer after the pulse is gone can be optimized and, for the pulse considered here, an enhancement factor of 10{sup 6}-10{sup 8} was obtained.

  13. In vivo dynamic turnover of cerebral 13C isotopomers from [U- 13C]glucose

    NASA Astrophysics Data System (ADS)

    Xu, Su; Shen, Jun

    2006-10-01

    An INEPT-based 13C MRS method and a cost-effective and widely available 11.7 Tesla 89-mm bore vertical magnet were used to detect dynamic 13C isotopomer turnover from intravenously infused [U- 13C]glucose in a 211 μL voxel located in the adult rat brain. The INEPT-based 1H → 13C polarization transfer method is mostly adiabatic and therefore minimizes signal loss due to B 1 inhomogeneity of the surface coils used. High quality and reproducible data were acquired as a result of combined use of outer volume suppression, ISIS, and the single-shot three-dimensional localization scheme built in the INEPT pulse sequence. Isotopomer patterns of both glutamate C4 at 34.00 ppm and glutamine C4 at 31.38 ppm are dominated first by a doublet originated from labeling at C4 and C5 but not at C3 (with 1JC4C5 = 51 Hz) and then by a quartet originated from labeling at C3, C4, and C5 (with 1JC3C4 = 35 Hz). A lag in the transition of glutamine C4 pattern from doublet-dominance to quartet dominance as compared to glutamate C4 was observed, which provides an independent verification of the precursor-product relationship between neuronal glutamate and glial glutamine and a significant intercompartmental cerebral glutamate-glutamine cycle between neurons and glial cells.

  14. Calculation of total meal d13C from individual food d13C.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variations in the isotopic signature of carbon in biological samples can be used to distinguish dietary patterns and monitor shifts in metabolism. But for these variations to have meaning, the isotopic signature of the diet must be known. We sought to determine if knowledge of the 13C isotopic abund...

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

    DOEpatents

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

    2003-01-01

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

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

    DOEpatents

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

    2004-05-04

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

  17. Accurate measurements of 13C-13C distances in uniformly 13C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Khaneja, Navin; Nielsen, Niels Chr.

    2014-09-01

    Application of sets of 13C-13C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important 13C-13C distances in uniformly 13C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl (13C') and aliphatic (13Caliphatic) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly 13C,15N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of 13C'-13Caliphatic distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform 13C,15N-labeling on the FGAIL fragment.

  18. Millimeter and submillimeter wave spectra of 13C-glycolaldehydes

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Motiyenko, R. A.; Margulès, L.; Huet, T. R.

    2013-01-01

    Context. Glycolaldehyde (CH2OHCHO) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. Astronomical surveys of interstellar molecules, such as those available with the very sensitive ALMA telescope, require preliminary laboratory investigations of the microwave and submillimeter-wave spectra of molecular species including new isotopologs - to identify these in the interstellar media. Aims: To achieve the detection of the 13C isotopologs of glycolaldehyde in the interstellar medium, their rotational spectra in the millimeter and submillimeter-wave regions were studied. Methods: The spectra of 13CH2OHCHO and CH2OH13CHO were recorded in the 150-945 GHz spectral range in the laboratory using a solid-state submillimeter-wave spectrometer in Lille. The observed line frequencies were measured with an accuracy of 30 kHz up to 700 GHz and of 50 kHz above 700 GHz. We analyzed the spectra with a standard Watson Hamiltonian. Results: About 10 000 new lines were identified for each isotopolog. The spectroscopic parameters were determined for the ground- and the three lowest vibrational states up to 945 and 630 GHz. Previous microwave assignments of 13CH2OHCHO were not confirmed. Conclusions: The provided line-lists and sets of molecular parameters meet the needs for a first astrophysical search of 13C-glycolaldehydes. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A96

  19. Evaluating Iron Content and Tissue Microstructure with Off-Resonance Saturation MRI

    NASA Astrophysics Data System (ADS)

    Fahmy, Sherif R.

    We present three magnetic resonance imaging (MRI) studies, each focused on applying off-resonance saturation (ORS) imaging to a different context or application. Particularly, we are interested in using ORS to evaluate the uptake of superparamagnetic MRI contrast agents in biological tissue, and to evaluate endogenous iron content. This relies on ORS being applied at low off-resonance frequency offsets where most of the negative contrast is due to signal loss from direct saturation of the water content of the sample. Additionally, we wish to combine this information with magnetization transfer contrast, which is obtained by applying ORS at offsets that are far from the resonance frequency, where magnetization transfer (MT) becomes the dominant effect rather than direct saturation (DS). In the first study, we observed the uptake of ultra-small superparamagnetic iron oxide (USPIO) nanoparticles in a simple model system by imaging the uptake in healthy murine liver in vivo, and by testing different metrics to quantify the uptake. Through this process, we discovered an approach that provides high sensitivity and specificity in low-signal scenarios. In the second study, we evaluated image contrast between brain regions in healthy human adults, and related these to the expected iron content in different regions based on age. Images were evaluated based on different MRI contrast mechanisms including quantitative transverse relaxation rates, as well as parameters obtained from ORS imaging. We also performed a field inhomogeneity adjustment on low-offset ORS data using the information obtained from the coarsely sampled ORS spectrum, and this was sufficient to correct for the inhomogeneities. In the third study, we used transverse relaxation, DS - which is strongly dependent on iron content, and MT contrast, in order to classify ex vivo brain samples having Alzheimer's disease pathology and normal controls, and were able to find strong classifiers. The three studies helped

  20. Off-Resonance Photosensitization of a Photorefractive Polymer Composite Using PbS Nanocrystals

    SciTech Connect

    Moon, Jong-Sik; Liang, Yichen; Stevens, Tyler E.; Monson, Todd C.; Huber, Dale L.; Mahala, Benjamin D.; Winiarz, Jeffrey G.

    2015-05-26

    The photosensitization of photorefractive polymeric composites for operation at 633 nm is accomplished through the inclusion of narrow band gap semiconductor nanocrystals composed of PbS. Unlike previous studies involving photosensitization of photorefractive polymer composites with inorganic nanocrystals, we employ an off-resonance approach where the first excitonic transition associated with the PbS nanocrystals lies at ~1220 nm and not the wavelength of operation. Using this methodology, internal diffraction efficiencies exceeding 82%, two-beam-coupling gain coefficients of 211 cm–1, and response times of 34 ms have been observed, representing some of the best figures of merit reported for this class of materials. Furthermore, these data demonstrate the ability of semiconductor nanocrystals to compete effectively with traditional organic photosensitizers. In addition to superior performance, this approach also offers an inexpensive and easy means by which to photosensitize composite materials. Additionally, the photoconductive characteristics of the composites used for this study will also be considered.

  1. Off-Resonance Photosensitization of a Photorefractive Polymer Composite Using PbS Nanocrystals

    DOE PAGES

    Moon, Jong-Sik; Liang, Yichen; Stevens, Tyler E.; ...

    2015-05-26

    The photosensitization of photorefractive polymeric composites for operation at 633 nm is accomplished through the inclusion of narrow band gap semiconductor nanocrystals composed of PbS. Unlike previous studies involving photosensitization of photorefractive polymer composites with inorganic nanocrystals, we employ an off-resonance approach where the first excitonic transition associated with the PbS nanocrystals lies at ~1220 nm and not the wavelength of operation. Using this methodology, internal diffraction efficiencies exceeding 82%, two-beam-coupling gain coefficients of 211 cm–1, and response times of 34 ms have been observed, representing some of the best figures of merit reported for this class of materials. Furthermore,more » these data demonstrate the ability of semiconductor nanocrystals to compete effectively with traditional organic photosensitizers. In addition to superior performance, this approach also offers an inexpensive and easy means by which to photosensitize composite materials. Additionally, the photoconductive characteristics of the composites used for this study will also be considered.« less

  2. Hyperpolarized 13C Metabolic MRI of the Human Heart

    PubMed Central

    Lau, Justin Y.C.; Chen, Albert P.; Geraghty, Benjamin J.; Perks, William J.; Roifman, Idan; Wright, Graham A.; Connelly, Kim A.

    2016-01-01

    Rationale: Altered cardiac energetics is known to play an important role in the progression toward heart failure. A noninvasive method for imaging metabolic markers that could be used in longitudinal studies would be useful for understanding therapeutic approaches that target metabolism. Objective: To demonstrate the first hyperpolarized 13C metabolic magnetic resonance imaging of the human heart. Methods and Results: Four healthy subjects underwent conventional proton cardiac magnetic resonance imaging followed by 13C imaging and spectroscopic acquisition immediately after intravenous administration of a 0.1 mmol/kg dose of hyperpolarized [1-13C]pyruvate. All subjects tolerated the procedure well with no adverse effects reported ≤1 month post procedure. The [1-13C]pyruvate signal appeared within the chambers but not within the muscle. Imaging of the downstream metabolites showed 13C-bicarbonate signal mainly confined to the left ventricular myocardium, whereas the [1-13C]lactate signal appeared both within the chambers and in the myocardium. The mean 13C image signal:noise ratio was 115 for [1-13C]pyruvate, 56 for 13C-bicarbonate, and 53 for [1-13C]lactate. Conclusions: These results represent the first 13C images of the human heart. The appearance of 13C-bicarbonate signal after administration of hyperpolarized [1-13C]pyruvate was readily detected in this healthy cohort (n=4). This shows that assessment of pyruvate metabolism in vivo in humans is feasible using current technology. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02648009. PMID:27635086

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

    DOEpatents

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

    2004-07-20

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

  4. /sup 13/C nuclear magnetic resonance studies of cardiac metabolism

    SciTech Connect

    Seeholzer, S.H.

    1985-01-01

    The last decade has witnessed the increasing use of Nuclear Magnetic Resonance (NMR) techniques for following the metabolic fate of compounds specifically labeled with /sup 13/C. The goals of the present study are: (1) to develop reliable quantitative procedures for measuring the /sup 13/C enrichment of specific carbon sites in compounds enriched by the metabolism of /sup 13/C-labeled substrates in rat heart, and (2) to use these quantitative measurements of fractional /sup 13/C enrichment within the context of a mathematical flux model describing the carbon flow through the TCA cycle and ancillary pathways, as a means for obtaining unknown flux parameters. Rat hearts have been perfused in vitro with various combinations of glucose, acetate, pyruvate, and propionate to achieve steady state flux conditions, followed by perfusion with the same substrates labeled with /sup 13/C in specific carbon sites. The hearts were frozen at different times after addition of /sup 13/C-labeled substrates and neutralized perchloric acid extracts were used to obtain high resolution proton-decoupled /sup 13/C NMR spectra at 90.55 MHz. The fractional /sup 13/C enrichment (F.E.) of individual carbon sites in different metabolites was calculated from the area of the resolved resonances after correction for saturation and nuclear Overhauser effects. These F.E. measurements by /sup 13/C NMR were validated by the analysis of /sup 13/C-/sup 1/H scalar coupling patterns observed in /sup 1/H NMR spectra of the extracted metabolites. The results obtained from perfusion of hearts glucose plus either (2-/sup 13/C) acetate or (3-/sup 13/C) pyruvate are similar to those obtained by previous investigators using /sup 14/C-labeled substrates.

  5. Dynamic imaging of a single gold nanoparticle in liquid irradiated by off-resonance femtosecond laser

    NASA Astrophysics Data System (ADS)

    Boutopoulos, Christos; Hatef, Ali; Fortin-Deschênes, Matthieu; Meunier, Michel

    2015-07-01

    Plasmonic nanoparticles can lead to extreme confinement of the light in the near field. This unique ability of plasmonic nanoparticles can be used to generate nanobubbles in liquid. In this work, we demonstrate with single-particle monitoring that 100 nm gold nanoparticles (AuNPs) irradiated by off-resonance femtosecond (fs) laser in the tissue therapeutic optical window (λ = 800 nm), can act as a durable nanolenses in liquid and provoke nanocavitation while remaining intact. We have employed combined ultrafast shadowgraphic imaging, in situ dark field imaging and dynamic tracking of AuNP Brownian motion to ensure the study of individual AuNPs/nanolenses under multiple fs laser pulses. We demonstrate that 100 nm AuNPs can generate multiple, highly confined (radius down to 550 nm) and transient (life time < 50 ns) nanobubbles. The latter is of significant importance for future development of in vivo AuNP-assisted laser nanosurgery and theranostic applications, where AuNP fragmentation should be avoided to prevent side effects, such as cytotoxicity and immune system's response. The experimental results have been correlated with theoretical modeling to provide an insight to the AuNP-safe cavitation mechanism as well as to investigate the deformation mechanism of the AuNPs at high laser fluences.Plasmonic nanoparticles can lead to extreme confinement of the light in the near field. This unique ability of plasmonic nanoparticles can be used to generate nanobubbles in liquid. In this work, we demonstrate with single-particle monitoring that 100 nm gold nanoparticles (AuNPs) irradiated by off-resonance femtosecond (fs) laser in the tissue therapeutic optical window (λ = 800 nm), can act as a durable nanolenses in liquid and provoke nanocavitation while remaining intact. We have employed combined ultrafast shadowgraphic imaging, in situ dark field imaging and dynamic tracking of AuNP Brownian motion to ensure the study of individual AuNPs/nanolenses under multiple fs

  6. 13C NMR Metabolomics: Applications at Natural Abundance

    PubMed Central

    2015-01-01

    13C NMR has many advantages for a metabolomics study, including a large spectral dispersion, narrow singlets at natural abundance, and a direct measure of the backbone structures of metabolites. However, it has not had widespread use because of its relatively low sensitivity compounded by low natural abundance. Here we demonstrate the utility of high-quality 13C NMR spectra obtained using a custom 13C-optimized probe on metabolomic mixtures. A workflow was developed to use statistical correlations between replicate 1D 13C and 1H spectra, leading to composite spin systems that can be used to search publicly available databases for compound identification. This was developed using synthetic mixtures and then applied to two biological samples, Drosophila melanogaster extracts and mouse serum. Using the synthetic mixtures we were able to obtain useful 13C–13C statistical correlations from metabolites with as little as 60 nmol of material. The lower limit of 13C NMR detection under our experimental conditions is approximately 40 nmol, slightly lower than the requirement for statistical analysis. The 13C and 1H data together led to 15 matches in the database compared to just 7 using 1H alone, and the 13C correlated peak lists had far fewer false positives than the 1H generated lists. In addition, the 13C 1D data provided improved metabolite identification and separation of biologically distinct groups using multivariate statistical analysis in the D. melanogaster extracts and mouse serum. PMID:25140385

  7. Off-Resonance Saturation MRI of Superparamagnetic Nanoprobes: Theoretical Models and Experimental Validations

    PubMed Central

    Khemtong, Chalermchai; Togao, Osamu; Ren, Jimin; Kessinger, Chase W.; Takahashi, Masaya; Sherry, A. Dean; Gao, Jinming

    2011-01-01

    Off-resonance saturation (ORS) is a new magnetic resonance imaging (MRI) method that has shown greatly improved contrast sensitivity for the detection of cancer-specific biomarkers by superparamagnetic nanoprobes in vivo. However, quantitative understanding of the ORS contrast mechanism and its dependence on the structural parameters of superparamagnetic nanoprobes are still lacking. Here we propose a quantitative model of ORS contrast and its experimental validation by superparamagnetic polymeric micelles (SPPM) with precisely controlled structural properties. Size selected, monodisperse Fe3O4 nanoparticles (6.1 ± 0.2 nm) were used to form a series of SPPM nanoprobes with specifically controlled corona thickness using 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxypoly(ethylene glycol) (DSPE-PEG) with different PEG molecular weights. Transmission electron microscopy and dynamic light scattering showed that SPPM were uniform in size. The average hydrodynamic diameters of SPPM with PEG lengths of 0.55, 1, 2, and 5 kD were 16.6 ± 2.8, 18.4 ± 2.9, 24.1 ± 3.4, and 28.9 ± 3.4 nm, respectively. MRI experiments at 7T determined that r2 values of SPPM with 0.55, 1, 2, and 5 kD PEG as corona were 201 ± 3, 136 ± 8, 107 ± 5, and 108 ± 8 Fe mM-1s-1, respectively. ORS intensity from Z-spectra of SPPM showed a significant correlation with the inverse of T2 relaxation rates (1/T2, s-1) of the SPPM nanoprobes regardless of the PEG corona thickness. These data provide the fundamental understanding of the structure-property relationships between the SPPM nanostructures and ORS sensitivity, which offers useful mechanistic insights for the future improvement of SPPM nanoprobes in cancer molecular imaging applications. PMID:21277813

  8. [Joint correction for motion artifacts and off-resonance artifacts in multi-shot diffusion magnetic resonance imaging].

    PubMed

    Wu, Wenchuan; Fang, Sheng; Guo, Hua

    2014-06-01

    Aiming at motion artifacts and off-resonance artifacts in multi-shot diffusion magnetic resonance imaging (MRI), we proposed a joint correction method in this paper to correct the two kinds of artifacts simultaneously without additional acquisition of navigation data and field map. We utilized the proposed method using multi-shot variable density spiral sequence to acquire MRI data and used auto-focusing technique for image deblurring. We also used direct method or iterative method to correct motion induced phase errors in the process of deblurring. In vivo MRI experiments demonstrated that the proposed method could effectively suppress motion artifacts and off-resonance artifacts and achieve images with fine structures. In addition, the scan time was not increased in applying the proposed method.

  9. /sup 1/H and /sup 13/C spin-lattice relaxation in gaseous benzene

    SciTech Connect

    Folkendt, M.M.; Weiss-Lopez, B.E.; True, N.S.

    1988-08-25

    The nuclear spin-lattice relaxation time, T/sub 1/, measured for benzene protons at densities between 0.81 and 54.4 mol/m/sup 3/ (15 and 980 Torr) at 381 K exhibits a characteristic nonlinear density dependence. Analysis of the density-dependent T/sub 1/ data yields a spin-rotation coupling constant, C/sub eff/, of /vert bar/182.6 (0.4)/vert bar/ Hz and an angular momentum reorientation cross section, sigma, of 131 (1) /Angstrom//sup 2/. The /sup 13/C spin-lattice relaxation time of singly labeled /sup 13/C benzene is a linear function of density over the density range 1.07-75.12 mol/m/sup 3/ (20-1330 Torr). /sup 13/C T/sub 1/ values are shorter than /sup 1/H T/sub 1/ values by a factor of ca. 100 at comparable densities. The nuclear Overhauser enhancement factor, /eta/, is 0.0 /plus minus/ 0.02 at densities between 11 and 85.3 mol/m/sup 3/ (200 and 1500 Torr), demonstrating that dipole-dipole relaxation is relatively inefficient in this region. The spin-rotation coupling constant, C/sub eff/, for /sup 13/C nuclei in benzene is estimated to be /vert bar/1602 (68)/vert bar/ Hz.

  10. Mass spectroscopy of laser ablated samples ionized by a microwave induced plasma and off-resonant laser radiation

    SciTech Connect

    Uebbing, J.; Niemax, K.

    1995-04-01

    The technique laser ablation of solid samples into a low pressure argon microwave induced plasma (MIP) is coupled with mass spectrometry. Additionally, an excimer laser or a dye laser are used for off-resonant and resonant ionization, respectively. It is demonstrated with copper, steel, brass, glass and ceramic samples, that, in first approximation, matrix-independent analysis is possible if internal standardization is applied.

  11. High homogeneity B(1) 30.2 MHz Nuclear Magnetic Resonance Probe for off-resonance relaxation times measurements.

    PubMed

    Baranowski, M; Woźniak-Braszak, A; Jurga, K

    2011-01-01

    This paper reports on design and construction of a double coil high-homogeneity ensuring Nuclear Magnetic Resonance Probe for off-resonance relaxation time measurements. NMR off-resonance experiments pose unique technical problems. Long irradiation can overheat the sample, dephase the spins because of B(1) field inhomogeneity and degrade the signal received by requiring the receiver bandwidth to be broader than that needed for normal experiment. The probe proposed solves these problems by introducing a separate off-resonance irradiation coil which is larger than the receiver coil and is wound up on the dewar tube that separates it from the receiver coil thus also thermally protects the sample from overheating. Large size of the irradiation coil also improves the field homogeneity because as a ratio of the sample diameter to the magnet (coil) diameter increases, the field inhomogeneity also increases (Blümich et al., 2008) [1]. The small receiver coil offers maximization of the filling factor and a high signal to the noise ratio.

  12. Investigation on driving characteristics of a piezoelectric stick–slip actuator based on resonant/off-resonant hybrid excitation

    NASA Astrophysics Data System (ADS)

    Cheng, Tinghai; Li, Hengyu; He, Meng; Zhao, Hongwei; Lu, Xiaohui; Gao, Haibo

    2017-03-01

    A resonant/off-resonant hybrid excitation of a piezoelectric stick–slip actuator is proposed in this paper. It is accomplished by a resonant sinusoidal friction regulation wave (RSFR-wave) and an off-resonant saw-tooth wave (ORST-wave). The RSFR-wave is applied to the rapid deformation stage of the ORST-wave. In this stage, the first-order longitudinal vibration mode of the stator can be obtained. By this longitudinal vibration mode, the kinetic friction between the slider and frictional rod is obviously decreased utilizing ultrasonic friction reduction. The backward displacement is remarkably restrained. The high velocity, large mass of load and smooth displacement are achieved. The operation principle of hybrid excitation was discussed in detail, and a prototype was simulated, designed, and fabricated. A series of experiments were carried out and the results indicate that the step efficiency under the saw-tooth excitation and resonant/off-resonant hybrid excitation can realize 36.9% and 91.2%, respectively. The output velocity is increased by 147.23% relative to saw-tooth excitation. The minimum input power and the minimum driving voltage are decreased by 89.56% and 58.33%, respectively. Besides, the maximum mass of load capacity is 2.88 times that of saw-tooth excitation. The driving capacity of the actuator is increased by 466.13%.

  13. Hyperpolarized 13C MR Markers of Renal Tumor Aggressiveness

    DTIC Science & Technology

    2013-10-01

    reliably distinguish renal cancer aggressiveness for optimal triage of therapies . Hyperpolarized (HP) 13C magnetic resonance spectroscopic imaging (MRSI...reliably distinguish renal cancer aggressiveness for optimal triage of therapies . Hyperpolarized (HP) 13C magnetic resonance spectroscopic imaging (MRSI) is... cancer and normal tissues were obtained from nephrectomy specimens and sliced using Krumdieck slicer. With a precision gauge micrometer, the slice

  14. Functional groups identified by solid state 13C NMR spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...

  15. Linking Biogeochemistry to Microbial Diversity Using New 13C Approaches

    NASA Astrophysics Data System (ADS)

    Baggs, E. M.

    2005-12-01

    The use of 13C enables us to overcome uncertainties associated with soil C processes and to assess the links between species diversity and ecosystem function. Recent advances in stable isotope techniques enable determination of process rates, for example CH4 oxidation by direct measurement of 13C-CH4 and 13C-CO2. This overcomes uncertainties associated with reliance on changes in net CH4 emission, which may have compromised some earlier studies as both methanogenesis and CH4 oxidation may occur simultaneously in soil, providing significant advances in our understanding of the process of CH4 oxidation. These stable isotope techniques can be combined with molecular techniques (analysis of gene expression, stable isotope probing (SIP)) to relate the measured process to the microbial populations responsible. Here we will give a synthesis of results from experiments in which we applied 13C-CH4 to accurately determine CH4 oxidation rates in soils, and also present results of 13C-SIP from which we can identify the key players in the microbial population that are using the applied 13C substrate. With the 13C-CH4 technique we were able to provide direct evidence of inhibition of CH4 oxidation following fertiliser application (50-300 kg N ha-1) that was less under elevated pCO2, and evidence for anaerobic CH4 oxidation occurring in soil at 75% soil water filled pore space that would not have been apparent from changes in net CH4 emissions. 13C-SIP both through plants (using 13C-CO2) and directly into soil (using 13C-methane and -organic substrates) has revealed how key players in C utilisation vary under different soil conditions, for example, under improved and unimproved grasslands.

  16. Novel Imaging Contrast Methods for Hyperpolarized 13 C Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Reed, Galen Durant

    Magnetic resonance imaging using hyperpolarized 13C-labeled small molecules has emerged as an extremely powerful tool for the in vivo monitoring of perfusion and metabolism. This work presents methods for improved imaging, parameter mapping, and image contrast generation for in vivo hyperpolarized 13C MRI. Angiography using hyperpolarized urea was greatly improved with a highly T2-weighted acquisition in combination with 15N labeling of the urea amide groups. This is due to the fact that the T2 of [13C]urea is strongly limited by the scalar coupling to the neighboring quadrupolar 14N. The long in vivo T2 values of [13C, 15N2]urea were utilized for sub-millimeter projection angiography using a contrast agent that could be safely injected in concentrations of 10-100 mM while still tolerated in patients with renal insufficiency. This study also presented the first method for in vivo T2 mapping of hyperpolarized 13C compounds. The in vivo T2 of urea was short in the blood and long within the kidneys. This persistent signal component was isolated to the renal filtrate, thus enabling for the first time direct detection of an imaging contrast agent undergoing glomerular filtration. While highly T2-weighted acquisitions select for molecules with short rotational correlation times, high diffusion weighting selects for those with the long translational correlation times. A specialized spin-echo EPI sequence was developed in order to generate highly diffusion-weighted hyperpolarized 13C images on a clinical MRI system operating within clinical peak- RF and gradient amplitude constraints. Low power adiabatic spin echo pulses were developed in order to generate a sufficiently large refocused bandwidth while maintaining low nominal power. This diffusion weighted acquisition gave enhanced tumor contrast-to-noise ratio when imaging [1-13C]lactate after infusion of [1-13C]pyruvate. Finally, the first in-man hyperpolarized 13C MRI clinical trial is discussed.

  17. Distinct fungal and bacterial δ13C signatures can drive the increase in soil δ13C with depth

    NASA Astrophysics Data System (ADS)

    Kohl, Lukas; Laganièrea, Jérôme; Edwards, Kate A.; Billings, Sharon A.; Morrill, Penny L.; Van Biesen, Geert; Ziegler, Susan E.

    2015-04-01

    Soil microbial biomass is a key precursor of soil organic carbon (SOC), and the enrichment in 13C during SOC diagenesis has been purported to be driven by increasing proportions of microbially derived SOC. Yet, little is known about how the δ13C of soil microbial biomass - and by extension the δ13C of microbial inputs to SOC - vary in space, time, or with the composition of the microbial community. Phospholipid fatty acids (PLFA) can be analyzed to measure the variation of the natural abundance δ13C values of both individual groups of microorganisms and the microbial community as a whole. Here, we show how variations of δ13CPLFA within the soil profile provides insight into C fluxes in undisturbed soils and demonstrate that distinct δ13C of fungal and bacterial biomass and their relative abundance can drive the increase of bulk δ13CSOC with depth. We studied the variation in natural abundance δ13C signatures of PLFA in podzolic soil profiles from mesic boreal forests in Atlantic Canada. Samples from the organic horizons (L,F,H) and the mineral (B; top 10 cm) horizons were analyzed for δ13C values of PLFA specific to fungi, G+ bacteria, or G- bacteria as proxies for the δ13C of the biomass of these groups, and for δ13C values of PLFA produced by a wide range of microorganisms (e.g. 16:0) as a proxy for the δ13C value of microbial biomass as a whole. Results were compared to fungi:bacteria ratios (F:B) and bulk δ13CSOC values. The δ13C values of group-specific PLFA were driven by differences among source organisms, with fungal PLFA consistently depleted (2.1 to 6.4‰) relative to and G+ and G- bacterial PLFA in the same sample. All group-specific PLFA, however, exhibited nearly constant δ13C values throughout the soil profile, apparently unaffected by the over 2.8‰ increase in δ13CSOC with depth from the L to B horizons. This indicates that bulk SOC poorly represents the substrates actually consumed by soil microorganisms in situ. Instead, our

  18. NMR structure analysis of uniformly 13C-labeled carbohydrates.

    PubMed

    Fontana, Carolina; Kovacs, Helena; Widmalm, Göran

    2014-06-01

    In this study, a set of nuclear magnetic resonance experiments, some of them commonly used in the study of (13)C-labeled proteins and/or nucleic acids, is applied for the structure determination of uniformly (13)C-enriched carbohydrates. Two model substances were employed: one compound of low molecular weight [(UL-(13)C)-sucrose, 342 Da] and one compound of medium molecular weight ((13)C-enriched O-antigenic polysaccharide isolated from Escherichia coli O142, ~10 kDa). The first step in this approach involves the assignment of the carbon resonances in each monosaccharide spin system using the anomeric carbon signal as the starting point. The (13)C resonances are traced using (13)C-(13)C correlations from homonuclear experiments, such as (H)CC-CT-COSY, (H)CC-NOESY, CC-CT-TOCSY and/or virtually decoupled (H)CC-TOCSY. Based on the assignment of the (13)C resonances, the (1)H chemical shifts are derived in a straightforward manner using one-bond (1)H-(13)C correlations from heteronuclear experiments (HC-CT-HSQC). In order to avoid the (1) J CC splitting of the (13)C resonances and to improve the resolution, either constant-time (CT) in the indirect dimension or virtual decoupling in the direct dimension were used. The monosaccharide sequence and linkage positions in oligosaccharides were determined using either (13)C or (1)H detected experiments, namely CC-CT-COSY, band-selective (H)CC-TOCSY, HC-CT-HSQC-NOESY or long-range HC-CT-HSQC. However, due to the short T2 relaxation time associated with larger polysaccharides, the sequential information in the O-antigen polysaccharide from E. coli O142 could only be elucidated using the (1)H-detected experiments. Exchanging protons of hydroxyl groups and N-acetyl amides in the (13)C-enriched polysaccharide were assigned by using HC-H2BC spectra. The assignment of the N-acetyl groups with (15)N at natural abundance was completed by using HN-SOFAST-HMQC, HNCA, HNCO and (13)C-detected (H)CACO spectra.

  19. Whole-core analysis by sup 13 C NMR

    SciTech Connect

    Vinegar, H.J.; Tutunjian, P.N. ); Edelstein, W.A.; Roemer, P.B. )

    1991-06-01

    This paper reports on a whole-core nuclear magnetic resonance (NMR) system that was used to obtain natural abundance {sup 13}C spectra. The system enables rapid, nondestructive measurements of bulk volume of movable oil, aliphatic/aromatic ratio, oil viscosity, and organic vs. carbonate carbon. {sup 13}C NMR can be used in cores where the {sup 1}H NMR spectrum is too broad to resolve oil and water resonances separately. A 5 1/4-in. {sup 13}C/{sup 1}H NMR coil was installed on a General Electric (GE) CSI-2T NMR imager/spectrometer. With a 4-in.-OD whole core, good {sup 13}C signal/noise ratio (SNR) is obtained within minutes, while {sup 1}H spectra are obtained in seconds. NMR measurements have been made of the {sup 13}C and {sup 1}H density of crude oils with a wide range of API gravities. For light- and medium-gravity oils, the {sup 13}C and {sup 1}H signal per unit volume is constant within about 3.5%. For heavy crudes, the {sup 13}C and {sup 1}H density measured by NMR is reduced by the shortening of spin-spin relaxation time. {sup 13}C and {sup 1}H NMR spin-lattice relaxation times were measured on a suite of Cannon viscosity standards, crude oils (4 to 60{degrees} API), and alkanes (C{sub 5} through C{sub 16}) with viscosities at 77{degrees}F ranging from 0.5 cp to 2.5 {times} 10{sup 7} cp. The {sup 13}C and {sup 1}H relaxation times show a similar correlation with viscosity from which oil viscosity can be estimated accurately for viscosities up to 100 cp. The {sup 13}C surface relaxation rate for oils on water-wet rocks is very low. Nonproton decoupled {sup 13}C NMR is shown to be insensitive to kerogen; thus, {sup 13}C NMR measures only the movable hydrocarbon content of the cores. In carbonates, the {sup 13}C spectrum also contains a carbonate powder pattern useful in quantifying inorganic carbon and distinguishing organic from carbonate carbon.

  20. Study of Urban environmental quality through Isotopes δ13C

    NASA Astrophysics Data System (ADS)

    González-Sosa, E.; Mastachi-Loza, C.; Becerril-Piña, R.; Ramos-Salinas, N. M.

    2012-04-01

    Usually, trees with similar pH values on their bark develop epiphytes of similar species, the acidity to be a factor for growth. The aim of the study was evaluate the air quality through isotope δ13C in order to define the levels of environmental quality in the city of Queretaro, Mexico. In this work were collected at least 4 epiphytes positioned in trees of the species Prosopis Laevigata at 25 sites of Queretaro City. The samples were analyzed for trace elements with an inductively coupled plasma atomic emission spectroscopy (ICP). The collecting took place during dry period, in May and early rain June 2011 period, and on four sectors to identify the spatial distribution of pollution, using isotopic analysis of concentration of δ 13C. According with the results there are significant differences among the species in each of the sampled areas. The 5 February Avenue presented greater diversity and richness of δ13C, followed by those who were surveyed in the proximity of the UAQ and finally in the middle-east area. An average value of δ13C-17.92%, followed by those surveyed in the vicinity of the UAQ that correspond to sector I and II with an concentration of δ13C-17.55% and δ13C-17.22%, and finally the samples collected in trees scattered in the East-Sector II and IV with a value of δ13C-17.02% and δ13C-15.62%, respectively. Also were observed differences between the dry and wet period. It is likely that these results of δ 13C in moist period reflect the drag of the isotopes due to rain events that could mark a trend in the dilution of this element, however there is a trend in terms of abundance and composition of finding more impact in those species sampled in dry period, in May and early June 2011.

  1. Fourier Transform Microwave Spectroscopy of Sc13C2 and Sc12C13C: Establishing AN Accurate Structure of ScC2 (tilde{X}2A1)

    NASA Astrophysics Data System (ADS)

    Burton, Mark; Halfen, DeWayne T.; Min, Jie; Ziurys, Lucy M.

    2016-06-01

    Pure rotational spectra of Sc13C2 and Sc12C13C (tilde{X}2A1) have been obtained using Fourier Transform Microwave methods. These molecules were created from scandium vapor in combination with 13CH4 and/or 12CH4, diluted in argon, using a Discharge Assisted Laser Ablation Source (DALAS). Transitions in the frequency range of 14-30 GHz were observed for both species including hyperfine splitting due to the nuclear spin of Sc (I = 7/2) and 13C (I = 1/2). Rotational, spin-rotational, and hyperfine constants have been determined for Sc13C2 and Sc12C13C, as well as a refined structure for ScC2. In agreement with theoretical calculations and previous Sc12C2 results, these data confirm a cyclic (or T-shaped) structure for this molecule. Scandium carbides have been shown to form endohedral-doped fullerenes, which have unique electrical and magnetic properties due to electron transfer between the metal and the carbon-cage. Spectroscopy of ScC2 provides data on model systems for comparison with theory.

  2. Constraining 3-PG with a new δ13C submodel: a test using the δ13C of tree rings.

    PubMed

    Wei, Liang; Marshall, John D; Link, Timothy E; Kavanagh, Kathleen L; DU, Enhao; Pangle, Robert E; Gag, Peter J; Ubierna, Nerea

    2014-01-01

    A semi-mechanistic forest growth model, 3-PG (Physiological Principles Predicting Growth), was extended to calculate δ(13)C in tree rings. The δ(13)C estimates were based on the model's existing description of carbon assimilation and canopy conductance. The model was tested in two ~80-year-old natural stands of Abies grandis (grand fir) in northern Idaho. We used as many independent measurements as possible to parameterize the model. Measured parameters included quantum yield, specific leaf area, soil water content and litterfall rate. Predictions were compared with measurements of transpiration by sap flux, stem biomass, tree diameter growth, leaf area index and δ(13)C. Sensitivity analysis showed that the model's predictions of δ(13)C were sensitive to key parameters controlling carbon assimilation and canopy conductance, which would have allowed it to fail had the model been parameterized or programmed incorrectly. Instead, the simulated δ(13)C of tree rings was no different from measurements (P > 0.05). The δ(13)C submodel provides a convenient means of constraining parameter space and avoiding model artefacts. This δ(13)C test may be applied to any forest growth model that includes realistic simulations of carbon assimilation and transpiration.

  3. Detection of inflammatory cell function using 13C magnetic resonance spectroscopy of hyperpolarized [6-13C]-arginine

    PubMed Central

    Najac, Chloé; Chaumeil, Myriam M.; Kohanbash, Gary; Guglielmetti, Caroline; Gordon, Jeremy W.; Okada, Hideho; Ronen, Sabrina M.

    2016-01-01

    Myeloid-derived suppressor cells (MDSCs) are highly prevalent inflammatory cells that play a key role in tumor development and are considered therapeutic targets. MDSCs promote tumor growth by blocking T-cell-mediated anti-tumoral immune response through depletion of arginine that is essential for T-cell proliferation. To deplete arginine, MDSCs express high levels of arginase, which catalyzes the breakdown of arginine into urea and ornithine. Here, we developed a new hyperpolarized 13C probe, [6-13C]-arginine, to image arginase activity. We show that [6-13C]-arginine can be hyperpolarized, and hyperpolarized [13C]-urea production from [6-13C]-arginine is linearly correlated with arginase concentration in vitro. Furthermore we show that we can detect a statistically significant increase in hyperpolarized [13C]-urea production in MDSCs when compared to control bone marrow cells. This increase was associated with an increase in intracellular arginase concentration detected using a spectrophotometric assay. Hyperpolarized [6-13C]-arginine could therefore serve to image tumoral MDSC function and more broadly M2-like macrophages. PMID:27507680

  4. IMPROVED LINE DATA FOR THE SWAN SYSTEM {sup 12}C{sup 13}C ISOTOPOLOGUE

    SciTech Connect

    Ram, Ram S.; Brooke, James S. A.; Bernath, Peter F.; Sneden, Christopher; Lucatello, Sara E-mail: rr662@york.ac.uk E-mail: chris@verdi.as.utexas.edu

    2014-03-01

    We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the {sup 12}C{sup 13}C isotopologue Swan d{sup 3}Π-a{sup 3}Π system 0-0, 0–1, 0–2, 1–0, 1–1, 1–2, 2–0, 2–1, and 2–2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the {sup 12}C{sup 13}C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The {sup 12}C{sup 13}C line data were combined with similar data for {sup 12}C{sub 2,} reported in a companion paper, and applied to produce synthetic spectra of carbon-rich metal-poor stars that have strong C{sub 2} Swan bands. The matches between synthesized and observed spectra were used to estimate band head positions for a few of the {sup 12}C{sup 13}C vibrational bands and to verify that the new computed line data match observed spectra. The much weaker C{sub 2} lines of the bright red giant Arcturus were also synthesized in the band head regions.

  5. (13)C metabolic flux analysis of recombinant expression hosts.

    PubMed

    Young, Jamey D

    2014-12-01

    Identifying host cell metabolic phenotypes that promote high recombinant protein titer is a major goal of the biotech industry. (13)C metabolic flux analysis (MFA) provides a rigorous approach to quantify these metabolic phenotypes by applying isotope tracers to map the flow of carbon through intracellular metabolic pathways. Recent advances in tracer theory and measurements are enabling more information to be extracted from (13)C labeling experiments. Sustained development of publicly available software tools and standardization of experimental workflows is simultaneously encouraging increased adoption of (13)C MFA within the biotech research community. A number of recent (13)C MFA studies have identified increased citric acid cycle and pentose phosphate pathway fluxes as consistent markers of high recombinant protein expression, both in mammalian and microbial hosts. Further work is needed to determine whether redirecting flux into these pathways can effectively enhance protein titers while maintaining acceptable glycan profiles.

  6. Synthesis of Site-Specifically (13)C Labeled Linoleic Acids.

    PubMed

    Offenbacher, Adam R; Zhu, Hui; Klinman, Judith P

    2016-10-12

    Soybean lipoxygenase-1 (SLO-1) catalyzes the C-H abstraction from the reactive carbon (C-11) in linoleic acid as the first and rate-determining step in the formation of alkylhydroperoxides. While previous labeling strategies have focused on deuterium labeling to ascertain the primary and secondary kinetic isotope effects for this reaction, there is an emerging interest and need for selectively enriched (13)C isotopologues. In this report, we present synthetic strategies for site-specific (13)C labeled linoleic acid substrates. We take advantage of a Corey-Fuchs formyl to terminal (13)C-labeled alkyne conversion, using (13)CBr4 as the labeling source, to reduce the number of steps from a previous fatty acid (13)C synthetic labeling approach. The labeled linoleic acid substrates are useful as nuclear tunneling markers and for extracting active site geometries of the enzyme-substrate complex in lipoxygenase.

  7. Anomalous 13C enrichment in modern marine organic carbon

    USGS Publications Warehouse

    Arthur, M.A.; Dean, W.E.; Claypool, G.E.

    1985-01-01

    Marine organic carbon is heavier isotopically (13C enriched) than most land-plant or terrestrial organic C1. Accordingly, ??13C values of organic C in modern marine sediments are routinely interpreted in terms of the relative proportions of marine and terrestrial sources of the preserved organic matter2,3. When independent geochemical techniques are used to evaluate the source of organic matter in Cretaceous or older rocks, those rocks containing mostly marine organic C are found typically to have lighter (more-negative) ??13C values than rocks containing mostly terrestrial organic C. Here we conclude that marine photosynthesis in mid-Cretaceous and earlier oceans generally resulted in a greater fractionation of C isotopes and produced organic C having lighter ??13C values. Modern marine photosynthesis may be occurring under unusual geological conditions (higher oceanic primary production rates, lower PCO2) that limit dissolved CO2 availability and minimize carbon isotope fractionation4. ?? 1985 Nature Publishing Group.

  8. Spin-locking of half-integer quadrupolar nuclei in NMR of solids: The far off-resonance case.

    PubMed

    Odedra, Smita; Wimperis, Stephen

    2016-11-30

    Spin-locking of spin I=3/2 and I=5/2 nuclei in the presence of large resonance offsets has been studied using both approximate and exact theoretical approaches and, in the case of I=3/2, experimentally. We show the variety of coherences and population states produced in a far off-resonance spin-locking NMR experiment (one consisting solely of a spin-locking pulse) and how these vary with the radiofrequency field strength and offset frequency. Under magic angle spinning (MAS) conditions and in the "adiabatic limit", these spin-locked states acquire a time dependence. We discuss the rotor-driven interconversion of the spin-locked states, using an exact density matrix approach to confirm the results of the approximate model. Using conventional and multiple-quantum filtered spin-locking (23)Na (I=3/2) NMR experiments under both static and MAS conditions, we confirm the results of the theoretical calculations, demonstrating the applicability of the approximate theoretical model to the far off-resonance case. This simplified model includes only the effects of the initial rapid dephasing of coherences that occurs at the start of the spin-locking period and its success in reproducing both experimental and exact simulation data indicates that it is this dephasing that is the dominant phenomenon in NMR spin-locking of quadrupolar nuclei, as we have previously found for the on-resonance and near-resonance cases. Potentially, far off-resonance spin-locking of quadrupolar nuclei could be of interest in experiments such as cross polarisation as a consequence of the spin-locking pulse being applied to a better defined initial state (the thermal equilibrium bulk magnetisation aligned along the z-axis) than can be created in a powdered solid with a selective radiofrequency pulse, where the effect of the pulse depends on the orientation of the individual crystallites.

  9. An in Vivo 13C NMR Analysis of the Anaerobic Yeast Metabolism of 1-13C-Glucose

    NASA Astrophysics Data System (ADS)

    Giles, Brent J.; Matsche, Zenziwe; Egeland, Ryan D.; Reed, Ryan A.; Morioka, Scott S.; Taber, Richard L.

    1999-11-01

    A biochemistry laboratory experiment that studies the dynamics of the anaerobic yeast metabolism of 1-13C-D-glucose via NMR is described. Fleischmann's Active Dry yeast, under anaerobic conditions, produces primarily 2-13C-ethanol and some 1-13C-glycerol as end products. An experiment is described in which the yeast is subjected to osmotic shock from an increasing sodium chloride concentration. Under these conditions, the yeast increases the ratio of glycerol to ethanol. The experiment can be accomplished in a single laboratory period.

  10. Spectrum of the cavity-QED microlaser: strong coupling effects in the frequency pulling at off resonance.

    PubMed

    Hong, H-G; Seo, W; Song, Y; Lee, M; Jeong, H; Shin, Y; Choi, W; Dasari, R R; An, K

    2012-12-14

    We report the first experimental observation of the cavity-QED microlaser spectrum, specifically the unconventional frequency pulling brought by a strong atom-cavity coupling at off resonance. The pulling is enhanced quadratically by the atom-cavity coupling to result in a sensitive response to the number of pumping atoms (2.1 kHz per atom maximally). Periodic variation of the pulling due to the coherent Rabi oscillation is also observed as the number of pumping atoms is increased across multiple thresholds.

  11. Dual resonant birdcage coils for 1H detected 13C microscopic imaging at 11.7 T.

    PubMed

    Hudson, A M; Köckenberger, W; Bowtell, R W

    2000-06-01

    Liquid state, rotating frame cross polarisation experiments are very sensitive to RF field inhomogeneity. In this work, we present an easily fabricated, co-resident high- and low-pass linear birdcage resonator, optimised to perform liquid state rotating frame polarisation transfer at 1H and 13C frequencies. Both the RF fields have been experimentally mapped, and used to validate the spatial signal dependence of a proton detected, 13C image. The predicted performance was then confirmed using PRAWN-based, cyclic J-cross polarisation (CYCLCROP) imaging. A novel variant of a B(1)-field mapping approach is also presented, using the signal enhancement of the CYCLCROP sequence to generate proton detected, 13C field maps.

  12. Computational study of plasma-assisted photoacoustic response from gold nanoparticles irradiated by off-resonance ultrafast laser

    NASA Astrophysics Data System (ADS)

    Hatef, Ali; Darvish, Behafarid; Sajjadi, Amir Yousef

    2017-02-01

    The gold nanoparticles (AuNPs) are capable of enhancing the incident laser field in the form of scattered near field for even an off-resonance irradiation where the incident laser wavelength is far away from the localized surface plasmon resonance (LSPR). If the intensity of the pulse laser is large enough, this capability can be employed to generate a highly localized free electron (plasma) in the vicinity of the particles. The generated plasma can absorb more energy during the pulse, and this energy deposition can be considered as an energy source for structural mechanics calculations in the surrounding media to generate a photoacoustic (PA) signal. To show this, in this paper, we model plasma-mediated PA pressure wave propagation from a 100-nm AuNPs and the surrounding media irradiated by an ultrashort pulse laser. In this model, the AuNP is immersed in water and the laser pulse width is ranging from 70 fs to 2 ps at the wavelength of 800 nm (off-resonance). Our results qualitatively show the substantial impact of the energy deposition in plasma on the PA signal through boosting the pressure amplitudes up to ˜1000 times compared to the conventional approach.

  13. 13C-based metabolic flux analysis: fundamentals and practice.

    PubMed

    Yang, Tae Hoon

    2013-01-01

    Isotope-based metabolic flux analysis is one of the emerging technologies applied to system level metabolic phenotype characterization in metabolic engineering. Among the developed approaches, (13)C-based metabolic flux analysis has been established as a standard tool and has been widely applied to quantitative pathway characterization of diverse biological systems. To implement (13)C-based metabolic flux analysis in practice, comprehending the underlying mathematical and computational modeling fundamentals is of importance along with carefully conducted experiments and analytical measurements. Such knowledge is also crucial when designing (13)C-labeling experiments and properly acquiring key data sets essential for in vivo flux analysis implementation. In this regard, the modeling fundamentals of (13)C-labeling systems and analytical data processing are the main topics we will deal with in this chapter. Along with this, the relevant numerical optimization techniques are addressed to help implementation of the entire computational procedures aiming at (13)C-based metabolic flux analysis in vivo.

  14. A scientific workflow framework for (13)C metabolic flux analysis.

    PubMed

    Dalman, Tolga; Wiechert, Wolfgang; Nöh, Katharina

    2016-08-20

    Metabolic flux analysis (MFA) with (13)C labeling data is a high-precision technique to quantify intracellular reaction rates (fluxes). One of the major challenges of (13)C MFA is the interactivity of the computational workflow according to which the fluxes are determined from the input data (metabolic network model, labeling data, and physiological rates). Here, the workflow assembly is inevitably determined by the scientist who has to consider interacting biological, experimental, and computational aspects. Decision-making is context dependent and requires expertise, rendering an automated evaluation process hardly possible. Here, we present a scientific workflow framework (SWF) for creating, executing, and controlling on demand (13)C MFA workflows. (13)C MFA-specific tools and libraries, such as the high-performance simulation toolbox 13CFLUX2, are wrapped as web services and thereby integrated into a service-oriented architecture. Besides workflow steering, the SWF features transparent provenance collection and enables full flexibility for ad hoc scripting solutions. To handle compute-intensive tasks, cloud computing is supported. We demonstrate how the challenges posed by (13)C MFA workflows can be solved with our approach on the basis of two proof-of-concept use cases.

  15. Synthesis and applications of {sup 13}C glycerol

    SciTech Connect

    Stocking, E.; Khalsa, O.; Martinez, R.A.; Silks, L.A. III

    1994-12-01

    Due in part to the use of labeled glycerol for the {sup 13}C enrichment of biomolecules, we are currently developing new synthetic routes to various isotopomers of glycerol. Judging from our experience, traditional methods of glycerol synthesis are not easily adapted for isotopic enrichment and/or have poor overall yields (12 to 15%). Furthermore, the use of glycerol for enrichment can be prohibitively expensive and its availability is limited by the level of demand. We are presently developing a short de novo synthesis of glycerol from carbon dioxide ({approximately}53% overall yield for four steps) and are examining the feasibility of synthesizing site-specific {sup 13}C-labeled glycerol and dihydroxyacetone (DHA) from labeled methanol and carbon dioxide. One application of {sup 13}C glycerol we have examined is enzymatic conversion of glycerol to glyceraldehyde-3-monophosphate or dihydroxyacetone monophosphate (DHAP) with yields ranging from 25 to 50% (as determined by NMR spectroscopy). We are also pursuing the chemical conversion of {sup 13}C-labeled DHA to DHAP. We are especially interested in {sup 13}C-labeled DHAP because we are investigating its use as a chemo-enzymatic precursor for both labeled 2-deoxyribose and 2-deoxyribonucleic acids.

  16. δ(13)C values of some succulent plants from Madagascar.

    PubMed

    Winter, Klaus

    1979-01-01

    δ(13)C values were determined in 20 succulents from Madagascar. The values were indicative of Crassulacean Acid Metabolism in 10 species of the Didiereaceae, 4 species of the Euphorbiaceae, 2 species of the Crassulaceae and 1 species of the Cucurbitaceae. The Didiereaceae and Euphorbiaceae studied are major components of a high biomass xerophytic flora in the semi-arid southwest and south of Madagascar. Three species of the Euphorbiaceae with succulent stems and non-succulent leaves, which were cultivated outdoors in the Tananarive Botanic Garden, showed C3 like δ(13)C values for both leaves and stems. δ(13)C values of leaf and stem material from a similar species, collected in the south of Madagascar, indicated Crassulacean Acid Metabolism.

  17. {sup 13}C relaxation in an RNA hairpin

    SciTech Connect

    King, G.C. |; Akratos, C.; Xi, Z.; Michnica, M.J.

    1994-12-01

    This initial survey of {sup 13}C relaxation in the {triangle}TAR RNA element has generated a number of interesting results that should prove generally useful for future studies. The most readily comparable study in the literature monitored {sup 13}C relaxation of the methyl groups from unusual bases in tRNA{sup Phe}. The study, which used T{sub 1} and NOE data only, reported order parameters for the methyl group axis that ranged between 0.51 and 0.97-a range similar to that observed here. However, they reported a breakdown of the standard order parameter analysis at higher (118-MHz {sup 13}C) frequencies, which should serve to emphasize the need for a thorough exploration of suitable motional models.

  18. Influence of 13C isotopic labeling location of 13C DNP of acetate using TEMPO free radical

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Lumata, Lloyd

    2015-03-01

    Dynamic nuclear polarization (DNP) via the dissolution method enhances the liquid-state magnetic resonance (NMR or MRI) signals of insensitive nuclear spins by at least 10,000-fold. The basis for all these signal enhancements at room temperature is the polarization transfer from the electrons to nuclear spins at cryogenic temperature and high magnetic field. In this work, we have studied the influence of the location of 13C isotopic labeling on the DNP of sodium acetate at 3.35 T and 1.4 K using a wide ESR linewidth free radical 4-oxo-TEMPO. The carbonyl [1-13C]acetate spins produced a polarization level that is almost twice that of the methyl [2-13C]acetate spins. On the other hand, the polarization of the methyl 13C spins doubled to reach the level of [1-13C]acetate when the methyl group was deuterated. Meanwhile, the solid-state nuclear relaxation of these samples are the same and do not correlate with the polarization levels. These behavior implies that the nuclear relaxation for these samples is dominated by the contribution from the free radicals and the polarization levels can be explained by a thermodynamic picture of DNP.

  19. Structure of uniaxially aligned 13C labeled silk fibroin fibers with solid state 13C-NMR

    NASA Astrophysics Data System (ADS)

    Demura, Makoto; Yamazaki, Yasunobu; Asakura, Tetsuo; Ogawa, Katsuaki

    1998-01-01

    Carbon-13 isotopic labeling of B. mori silk fibroin was achieved biosynthetically with [1- 13C] glycine in order to determine the carbonyl bond orientation angle of glycine sites with the silk fibroin. Angular dependence of 13C solid state NMR spectra of uniaxially oriented silk fibroin fiber block sample due to the carbonyl 13C chemical shift anisotropy was simulated according to the chemical shift transformation with Euler angles, αF and βF, from principal axis system (PAS) to fiber axis system (FAS). The another Euler angles, αDCO and βDCO, for transformation from PAS to the molecular symmetry axis were determined from the [1- 13C] glycine sequence model compounds for the silk fibroin. By the combination of these Euler angles, the carbonyl bond orientation angle with respect to FAS of the [1- 13C] glycine sites of the silk fibroin was determined to be 90 ± 5°. This value is in agreement with the X-ray diffraction and our previous solid state NMR data of B. mori silk fibroin fiber (a typical β-pleated sheet) within experimental error.

  20. Quantum computers based on electron spins controlled by ultrafast off-resonant single optical pulses.

    PubMed

    Clark, Susan M; Fu, Kai-Mei C; Ladd, Thaddeus D; Yamamoto, Yoshihisa

    2007-07-27

    We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broadband optical pulses to rotate electron spins and provide the clock signal to the system. Nonlocal two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency.

  1. Metabolic flux analysis using 13C peptide label measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    13C metabolic flux analysis (MFA) has become the experimental method of choice to investigate cellular metabolism. MFA has established flux maps of central metabolism for dozens of microbes, cell cultures, and plant seeds. Steady-state MFA utilizes isotopic labeling measurements of amino acids obtai...

  2. Quantitative 13C NMR characterization of fast pyrolysis oils

    DOE PAGES

    Happs, Renee M.; Lisa, Kristina; Ferrell, III, Jack R.

    2016-10-20

    Quantitative 13C NMR analysis of model catalytic fast pyrolysis (CFP) oils following literature procedures showed poor agreement for aromatic hydrocarbons between NMR measured concentrations and actual composition. Furthermore, modifying integration regions based on DEPT analysis for aromatic carbons resulted in better agreement. Solvent effects were also investigated for hydrotreated CFP oil.

  3. Modeling of the 2007 JET ^13C migration experiments

    NASA Astrophysics Data System (ADS)

    Strachan, J. D.; Likonen, J.; Hakola, A.; Coad, J. P.; Widdowson, A.; Koivuranta, S.; Hole, D. E.; Rubel, M.

    2010-11-01

    Using the last run day of the 2007 JET experimental campaign, ^13CH4 was introduced repeatedly from the vessel top into a single plasma type (H-mode, Ip= 1.6 MA, Bt= 1.6 T). Similar experiments were performed in 2001 (vessel top into L-Mode) and 2004 (outer divertor into H-Mode). Divertor and wall tiles were removed and been analysed using secondary ion mass spectrometry (SIMS) and Rutherford backscattering (RBS) to determine the ^13C migration. ^13C was observed to migrate both to the inner (largest deposit), outer divertor (less) , and the floor tiles (least). This paper reports the EDGE2D/NIMBUS based modelling of the carbon migration. The emphasis is on the comparison of the 2007 results with the 2001 results where both injections were from the machine top but ELMs were present in 2007 but not present in 2001. The ELMs seemed to cause more ^13C re-erosion near the inner strike point. Also of interest is the difference in the Private Flux Region deposits where the changes in divertor geometry between 2004 and 2007 caused differences in the deposits. In 2007, the tilting of the load bearing tile caused regions of the PFR to be shadowed from the inner strike point which were not shadowed in 2004, indicating ^13C neutrals originated from the OSP.

  4. Complete 1H and 13C spectral assignment of floridoside.

    PubMed

    Simon-Colin, Christelle; Kervarec, Nelly; Pichon, Roger; Deslandes, Eric

    2002-02-11

    Floridoside (2-O-alpha-D-galactopyranosylglycerol) was extracted from the red marine alga Rhodymenia palmata, and purified by ion-exchange chromatography: 1D and 2D NMR spectroscopy experiments were used to unambiguously assign the complete 1H and 13C spectra.

  5. Does the Shuram δ13C excursion record Ediacaran oxygenation?

    NASA Astrophysics Data System (ADS)

    Husson, J. M.; Maloof, A. C.; Schoene, B.; Higgins, J. A.

    2013-12-01

    The most negative carbon isotope excursion in Earth history is found in carbonate rocks of the Ediacaran Period (635-542 Ma). Known colloquially as the the 'Shuram' excursion, workers have long noted its tantalizing, broad concordance with the rise of abundant macro-scale fossils in the rock record, variously interpreted as animals, giant protists, macro-algae and lichen, and known as the 'Ediacaran Biota.' Thus, the Shuram excursion has been interpreted by many in the context of a dramatically changing redox state of the Ediacaran oceans - e.g., a result of methane cycling in a low O2 atmosphere, the final destruction of a large pool of recalcitrant dissolved organic carbon (DOC), and the step-wise oxidation of the Ediacaran oceans. More recently, diagenetic interpretations of the Shuram excursion - e.g. sedimentary in-growth of very δ13C depleted authigenic carbonates, meteoric alteration of Ediacaran carbonates, late-stage burial diagenesis - have challenged the various Ediacaran redox models. A rigorous geologic context is required to discriminate between these explanatory models, and determine whether the Shuram excursion can be used to evaluate terminal Neoproterozoic oxygenation. Here, we present chemo-stratigraphic data (δ13C, δ18O, δ44/42Ca and redox sensitive trace element abundances) from 12 measured sections of the Ediacaran-aged Wonoka Formation (Fm.) of South Australia that require a syn-depositional age for the extraordinary range of δ13C values (-12 to +4‰) observed in the formation. In some locations, the Wonoka Fm. is ~700 meters (m) of mixed shelf limestones and siliclastics that record the full 16 ‰ δ13C excursion in a remarkably consistent fashion across 100s of square kilometers of basin area. Fabric-altering diagenesis, where present, occurs at the sub-meter vertical scale, only results in sub-permil offsets in δ13C and cannot be used to explain the full δ13C excursion. In other places, the Wonoka Fm. is host to deep (1 km

  6. Using off-resonance laser modulation for beam-energy-spread cooling in generation of short-wavelength radiation.

    PubMed

    Deng, Haixiao; Feng, Chao

    2013-08-23

    To improve temporal coherence in electron beam based light sources, various techniques employ frequency up conversion of external seed sources via electron beam density modulation; however, the energy spread of the beam may hinder the harmonic generation efficiency. In this Letter, a method is described for cooling the electron beam energy spread by off-resonance seed laser modulation, through the use of a transversely dispersed electron beam and a modulator undulator with an appropriate transverse field gradient. With this novel mechanism, it is shown that the frequency up-conversion efficiency can be significantly enhanced. We present theoretical analysis and numerical simulations for seeded soft x-ray free-electron laser and storage ring based coherent harmonic generation in the extreme ultraviolet spectral region.

  7. Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

    DOEpatents

    Martinez, Rodolfo A. , Unkefer; Clifford J. , Alvarez; Marc, A [Santa Fe, NM

    2012-06-12

    The present invention is directed to the labeled compounds, ##STR00001## wherein C* is each either .sup.13C and .sup.12C where at least one C* is .sup.13C, each hydrogen of the methylene group is hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is sulfide, sulfinyl, or sulfone, Z is an aryl group such as 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, or a phenyl group ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently either hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group such as NH.sub.2, NHR and NRR' where R and R' are each independently either a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms. The present invention is also directed to the labeled compounds ##STR00003##

  8. Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

    DOEpatents

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

    2009-09-01

    The present invention is directed to labeled compounds, of the formulae ##STR00001## wherein C* is each independently selected from the group consisting of .sup.13C and .sup.12C with the proviso that at least one C* is .sup.13C, each hydrogen of the methylene group can independently be either hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is from the group of sulfide, sulfinyl, and sulfone, Z is an aryl group from the group of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently from the group of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group from the group of NH.sub.2, NHR and NRR' where R and R' are each independently from the group of a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms.

  9. Quantification of 13C pyruvate and 13C lactate in dog blood by reversed-phase liquid chromatography-electrospray ionization mass spectrometry after derivatization with 3-nitrophenylhydrazine.

    PubMed

    Uran, Steinar; Landmark, Kristin Eitrem; Hjellum, Gro; Skotland, Tore

    2007-08-15

    Injection of hyperpolarized (13)C-labelled pyruvate ((13)C pyruvate) is under evaluation as an agent for medical metabolic imaging by measuring formation of (13)C lactate using magnetic resonance spectroscopy of the (13)C nuclei. A quantitative method for analysis of these (13)C-labelled substances in dog blood was needed as part of the development of this agent and we here describe a liquid chromatography-mass spectrometry method for that purpose. Immediately after blood collection, the blood proteins were precipitated using methanol added internal standard ([U-(13)C]pyruvate and [U-(13)C]lactate). Prior to analysis, the compounds were derivatized using 3-nitrophenylhydrazine. Following separation on a Supelco Discovery HS C18 column, (13)C pyruvate and (13)C lactate were detected using negative electrospray ionization mass spectrometry. Calibration standards (4.5-4500 microM (13)C pyruvate and 9-9000 microM (13)C lactate) and added internal standard were used to make the calibration curves, which were fitted to a non-linear equation y=a+bx+cx(2) and weighted with a weighting factor of 1/y(2). The analytical lower limit of quantification of (13)C pyruvate and (13)C lactate was 4.5 and 9 microM, respectively. The total precision of the method was below 9.2% for (13)C pyruvate and below 5.8% for (13)C lactate. The accuracy of the method showed a relative error less than 2.4% for (13)C pyruvate and less than 6.3% for (13)C lactate. The recoveries were in the range 93-115% for (13)C pyruvate and 70-111% for (13)C lactate. Both substances were stable in protein-free supernatant when stored for up to 3 weeks in a -20 degrees C freezer, during three freeze/thaw cycles, and when stored in an autosampler for at least 30 h.

  10. Short-term d13C changes in cultivated soils from Mexico

    NASA Astrophysics Data System (ADS)

    Lounejeva, E.; Etchevers, J.; Morales Puente, P.; Cienfuegos Alvarado, E.; Sedov, S.; Solleiro, E.; Hidalgo, C.

    2007-05-01

    (generally less than -20%o). The common feature for the soils under the Traditional and Traditional improved treatments was a C3 enrichment of the superficial SOM component compared to the underlying layers as a consequence of the dominance of the cultivated C3 species. A similar but more accentuated negative shift is also observed in the SOM from the forest soil (non-cultivated soil d13C -25.2), so the interpretation is uncertain. In the Traditional Organic treatment a clear and perceptible increment of d13C in the SOM carbon signature was observed. This was attributed mainly to the fact that cows manure may contain a lot of C4 coming from feedstuff rich in corn grain that is provided to the animals during grass shortage periods . However, the maize crop introduced in the rotation during the 3rd year had no major effect on the tepetates carbon isotopic signature. The stable isotopic carbon data corresponding to a short period (4 years) of observation in uniformly managed soil ecosystems showed that d13C changed due to the quality of the residues (relative abundance of C3/C4 species) incorporated to the SOC, but this memory is susceptible to undergo changes in the short term and could be rapidly reversed as a consequence of crop management.

  11. Imaging pH with hyperpolarized 13C.

    PubMed

    Gallagher, Ferdia A; Kettunen, Mikko I; Brindle, Kevin M

    2011-10-01

    pH is a fundamental physiological parameter that is tightly controlled by endogenous buffers. The acid-base balance is altered in many disease states, such as inflammation, ischemia and cancer. Despite the importance of pH, there are currently no routine methods for imaging the spatial distribution of pH in humans. The enormous gain in sensitivity afforded by dynamic nuclear polarization (DNP) has provided a novel way in which to image tissue pH using MR, which has the potential to be translated into the clinic. This review explores the advantages and disadvantages of current pH imaging techniques and how they compare with DNP-based approaches for the measurement and imaging of pH with hyperpolarized (13)C. Intravenous injection of hyperpolarized (13)C-labeled bicarbonate results in the rapid production of hyperpolarized (13)CO(2) in the reaction catalyzed by carbonic anhydrase. As this reaction is close to equilibrium in the body and is pH dependent, the ratio of the (13)C signal intensities from H(13)CO(3)(-) and (13)CO(2), measured using MRS, can be used to calculate pH in vivo. The application of this technique to a murine tumor model demonstrated that it measured predominantly extracellular pH and could be mapped in the animal using spectroscopic imaging techniques. A second approach has been to use the production of hyperpolarized (13)CO(2) from hyperpolarized [1-(13)C]pyruvate to measure predominantly intracellular pH. In tissues with a high aerobic capacity, such as the heart, the hyperpolarized [1-(13)C]pyruvate undergoes rapid oxidative decarboxylation, catalyzed by intramitochondrial pyruvate dehydrogenase. Provided that there is sufficient carbonic anhydrase present to catalyze the rapid equilibration of the hyperpolarized (13)C label between CO(2) and bicarbonate, the ratio of their resonance intensities may again be used to estimate pH, which, in this case, is predominantly intracellular. As both pyruvate and bicarbonate are endogenous molecules they

  12. Solid-State 13C Nuclear Magnetic Resonance Characterization of Cellulose in the Cell Walls of Arabidopsis thaliana Leaves.

    PubMed Central

    Newman, R. H.; Davies, L. M.; Harris, P. J.

    1996-01-01

    Solid-state 13C nuclear magnetic resonance was used to characterize the molecular ordering of cellulose in a cell-wall preparation containing mostly primary walls obtained from the leaves of Arabidopsis thaliana. Proton and 13C spin relaxation time constants showed that the cellulose was in a crystalline rather than a paracrystalline state or amorphous state. Cellulose chains were distributed between the interiors (40%) and surfaces (60%) of crystallites, which is consistent with crystallite cross-sectional dimensions of about 3 nm. Digital resolution enhancement revealed signals indicative of triclinic and monoclinic crystalline forms of cellulose mixed in similar proportions. Of the five nuclear spin relaxation processes used, proton rotating-frame relaxation provided the clearest distinction between cellulose and other cell-wall components for purposes of editing solid-state 13C nuclear magnetic resonance spectra. PMID:12226303

  13. 13C Tracer Studies of Metabolism in Mouse Tumor Xenografts

    PubMed Central

    Lane, Andrew N.; Yan, Jun; Fan, Teresa W-M.

    2015-01-01

    Mice are widely used for human tumor xenograft studies of cancer development and drug efficacy and toxicity. Stable isotope tracing coupled with metabolomic analysis is an emerging approach for assaying metabolic network activity. In mouse models there are several routes of tracer introduction, which have particular advantages and disadvantages that depend on the model and the questions addressed. This protocol describes the bolus i.v. route via repeated tail vein injections of solutions of stable isotope enriched tracers including 13C6-glucose and 13C5,15N2-glutamine. Repeated injections give higher enrichments and over longer labeling periods than a single bolus. Multiple injections of glutamine are necessary to achieve adequate enrichment in engrafted tumors. PMID:26693168

  14. Galactose oxidation using (13)C in healthy and galactosemic children.

    PubMed

    Resende-Campanholi, D R; Porta, G; Ferrioli, E; Pfrimer, K; Ciampo, L A Del; Junior, J S Camelo

    2015-03-01

    Galactosemia is an inborn error of galactose metabolism that occurs mainly as the outcome of galactose-1-phosphate uridyltransferase (GALT) deficiency. The ability to assess galactose oxidation following administration of a galactose-labeled isotope (1-(13)C-galactose) allows the determination of galactose metabolism in a practical manner. We aimed to assess the level of galactose oxidation in both healthy and galactosemic Brazilian children. Twenty-one healthy children and seven children with galactosemia ranging from 1 to 7 years of age were studied. A breath test was used to quantitate (13)CO2 enrichment in exhaled air before and at 30, 60, and 120 min after the oral administration of 7 mg/kg of an aqueous solution of 1-(13)C-galactose to all children. The molar ratios of (13)CO2 and (12)CO2 were quantified by the mass/charge ratio (m/z) of stable isotopes in each air sample by gas-isotope-ratio mass spectrometry. In sick children, the cumulative percentage of (13)C from labeled galactose (CUMPCD) in the exhaled air ranged from 0.03% at 30 min to 1.67% at 120 min. In contrast, healthy subjects showed a much broader range in CUMPCD, with values from 0.4% at 30 min to 5.58% at 120 min. The study found a significant difference in galactose oxidation between children with and without galactosemia, demonstrating that the breath test is useful in discriminating children with GALT deficiencies.

  15. 13C NMR of Nephila clavipes major ampullate silk gland.

    PubMed

    Hijirida, D H; Do, K G; Michal, C; Wong, S; Zax, D; Jelinski, L W

    1996-12-01

    The major ampullate glands of the spider Nephila clavipes contain approximately 0.2 microliter each of a highly concentrated (approximately 50%) solution of silk fibroin. Therefore, the reservoir of silk in these glands presents an ideal opportunity to observe prefolded conformations of a protein in its native state. To this end, the structure and conformation of major ampullate gland silk fibroin within the glands of the spider N. clavipes were examined by 13C NMR spectroscopy. These results were compared to those from silk protein first drawn from the spinneret and then denatured. The 13C NMR chemical shifts, along with infrared and circular dichroism data, suggest that the silk fibroin in the glands exists in dynamically averaged helical conformations. Furthermore, there is no evidence of proline residues in U-(13)C-D-glucose-labeled silk. This transient prefolded "molten fibril" state may correspond to the silk I form found in Bombyx mori silk. There is no evidence of the final beta-sheet structure in the ampullate gland silk fibroin before final silk processing. However, the conformation of silk in the glands appears to be in a highly metastable state, as plasticization with water produces the beta-sheet structure. Therefore, the ducts connecting the ampullate glands to the spinnerets play a larger role in silk processing than previously thought.

  16. THz spectroscopy and first ISM detection of excited torsional states of 13C-methyl formate

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Carvajal, M.; Tercero, B.; Kleiner, I.; López, A.; Cernicharo, J.; Motiyenko, R. A.; Huet, T. R.; Guillemin, J. C.; Margulès, L.

    2014-08-01

    Context. An astronomical survey of interstellar molecular clouds needs a previous analysis of the spectra in the microwave and sub-mm energy range of organic molecules to be able to identify them. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of rotational spectra. These constants can be used to predict the transitions frequencies very precisely that were not measured in the laboratory. Aims: We present the experimental study and its theoretical analysis for two 13C-methyl formate isotopologues to detect these two isotopologues for the first time in their excited torsional states, which lie at 130 cm-1 (200 K) in Orion-KL. Methods: New spectra of HCOO13CH3 (13C2) methyl formate were recorded with the mm- and submm-wave spectrometer in Lille from 50 to 940 GHz. A global fit for vt = 0 and 1 was accomplished with the BELGI program to reproduce the experimental spectra with greater accuracy. Results: We analysed 5728 and 2881 new lines for vt = 0 and 1 for HCOO13CH3. These new lines were globally fitted with 846 previously published lines for vt = 0. In consequence, 52 parameters of the RAM Hamiltonian were accurately determined and the value of the barrier height (V3 = 369.93168(395) cm-1) was improved. We report the detection of the first excited torsional states (vt = 1) in Orion-KL for the 13C2 and 13C1 methyl formate based on the present analysis and previously published data. We provide column densities, isotopic abundances, and vibrational temperatures for these species. Conclusions: Following this work, accurate prediction can be provided. This permits detecting 135 features of the first excited torsional states of 13C-methyl formate isotopologues in Orion-KL in the 80-280 GHz frequency range, without missing lines. Full Table A.1 and the IRAM spectra as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568

  17. Phase stability in fMRI time series: effect of noise regression, off-resonance correction and spatial filtering techniques.

    PubMed

    Hagberg, Gisela E; Bianciardi, Marta; Brainovich, Valentina; Cassara, Antonino Mario; Maraviglia, Bruno

    2012-02-15

    Although the majority of fMRI studies exploit magnitude changes only, there is an increasing interest regarding the potential additive information conveyed by the phase signal. This integrated part of the complex number furnished by the MR scanners can also be used for exploring direct detection of neuronal activity and for thermography. Few studies have explicitly addressed the issue of the available signal stability in the context of phase time-series, and therefore we explored the spatial pattern of frequency specific phase fluctuations, and evaluated the effect of physiological noise components (heart beat and respiration) on the phase signal. Three categories of retrospective noise reduction techniques were explored and the temporal signal stability was evaluated in terms of a physiologic noise model, for seven fMRI measurement protocols in eight healthy subjects at 3T, for segmented CSF, gray and white matter voxels. We confirmed that for most processing methods, an efficient use of the phase information is hampered by the fact that noise from physiological and instrumental sources contributes significantly more to the phase than to the magnitude instability. Noise regression based on the phase evolution of the central k-space point, RETROICOR, or an orthonormalized combination of these were able to reduce their impact, but without bringing phase stability down to levels expected from the magnitude signal. Similar results were obtained after targeted removal of scan-to-scan variations in the bulk magnetic field by the dynamic off-resonance in k-space (DORK) method and by the temporal off-resonance alignment of single-echo time series technique (TOAST). We found that spatial high-pass filtering was necessary, and in vivo a Gaussian filter width of 20mm was sufficient to suppress physiological noise and bring the phase fluctuations to magnitude levels. Stronger filters brought the fluctuations down to levels dictated by thermal noise contributions, and for 62

  18. Thz Spectroscopy of 13C Isotopic Species of a "weed": Acetaldehyde

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.

    2011-06-01

    Our studies of the isotopic species of 13C and D isotopologues of methyl formate (HCOOCH_3), have allowed the detection of more than 600 lines in Orion. This confirms that many observed U-lines are coming from isotopic species of one of the most abundant molecules in space. Since its first detection in 1976 in SgrB2 and in Orion A, acetaldehyde (CH_3CHO) was detected in many other numerous objects. If its deuterated species (CD_3CHO and CH_3CDO) have been previously studied in the millimeterwave range, the data concerning the 13C species are limited to few lines measured in 1957 up to 40 GHz. In this context we decided to study the 13C species of acetaldehyde. Acetaldehyde molecule displays a large amplitude motion: the hindered rotation of the methyl group with respect to the rest of the molecule. The analysis is performed with the Rho Axis Method. Recent versions of the codes include high orders term in order to reproduce the observed frequencies for large quantum numbers values as J-values as high as 70a,b,. Measurements and analysis of the rotational spectra of 13C isotopic species are in progress in Lille with a solid-state submillimetre-wave spectrometer (50-950 GHz), the first results will be presented. This work is supported by the contract ANR-08-BLAN-0054 and by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS). Carvajal, M.; Margulès, L.; Tercero, B.; et al.A&A 500, (2009) 1109 Margulès, L.; Huet, T. R.; Demaison J.; et al.,ApJ 714, (2010) 1120. Ikeda, M.; Ohishi, M.; Nummelin, A.; et al., ApJ, 560, (2001) 792 Kleiner, I.; Lopez, J.-C.; Blanco, S.; et al.J. Mol. Spectrosc. 197, (1999) 275 Elkeurti M.; Coudert, L. H.; Medvedev, I. R.; et al.J. Mol. Spectrosc. 263, (2010) 145 Kilb, R.W.; Lin, C.C.; and Wilson, E.B.J. Chem. Phys. 26, (1957) 1695 Kleiner, I. J. Mol. Spectrosc. 260, (2010) 1 Ilyushin, V.V.; Kryvda, A; and Alekseev, E;J. Mol. Spectrosc. 255, (2009) 32

  19. In vivo investigation of cardiac metabolism in the rat using MRS of hyperpolarized [1-13C] and [2-13C]pyruvate.

    PubMed

    Josan, Sonal; Park, Jae Mo; Hurd, Ralph; Yen, Yi-Fen; Pfefferbaum, Adolf; Spielman, Daniel; Mayer, Dirk

    2013-12-01

    Hyperpolarized (13)C MRS allows the in vivo assessment of pyruvate dehydrogenase complex (PDC) flux, which converts pyruvate to acetyl-coenzyme A (acetyl-CoA). [1-(13)C]pyruvate has been used to measure changes in cardiac PDC flux, with demonstrated increase in (13)C-bicarbonate production after dichloroacetate (DCA) administration. With [1-(13)C]pyruvate, the (13)C label is released as (13 CO2 /(13)C-bicarbonate, and, hence, does not allow us to follow the fate of acetyl-CoA. Pyruvate labeled in the C2 position has been used to track the (13)C label into the TCA (tricarboxylic acid) cycle and measure [5-(13)C]glutamate as well as study changes in [1-(13)C]acetylcarnitine with DCA and dobutamine. This work investigates changes in the metabolic fate of acetyl-CoA in response to metabolic interventions of DCA-induced increased PDC flux in the fed and fasted state, and increased cardiac workload with dobutamine in vivo in rat heart at two different pyruvate doses. DCA led to a modest increase in the (13)C labeling of [5-(13)C]glutamate, and a considerable increase in [1-(13)C]acetylcarnitine and [1,3-(13)C]acetoacetate peaks. Dobutamine resulted in an increased labeling of [2-(13)C]lactate, [2-(13)C]alanine and [5-(13)C]glutamate. The change in glutamate with dobutamine was observed using a high pyruvate dose but not with a low dose. The relative changes in the different metabolic products provide information about the relationship between PDC-mediated oxidation of pyruvate and its subsequent incorporation into the TCA cycle compared with other metabolic pathways. Using a high dose of pyruvate may provide an improved ability to observe changes in glutamate.

  20. The 13C nuclear magnetic resonance in graphite intercalation compounds

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Resing, H. A.

    1985-01-01

    The (13)C NMR chemical shifts of graphite intercalation compounds were calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about -140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

  1. Quantum-Coherence-Assisted Tunable On- and Off-Resonance Tunneling through a Quantum-Dot-Molecule Dielectric Film

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi; Zeng, Rui Xi

    2017-02-01

    Quantum-dot-molecular phase coherence (and the relevant quantum-interference-switchable optical response) can be utilized to control electromagnetic wave propagation via a gate voltage, since quantum-dot molecules can exhibit an effect of quantum coherence (phase coherence) when quantum-dot-molecular discrete multilevel transitions are driven by an electromagnetic wave. Interdot tunneling of carriers (electrons and holes) controlled by the gate voltage can lead to destructive quantum interference in a quantum-dot molecule that is coupled to an incident electromagnetic wave, and gives rise to a quantum coherence effect (e.g., electromagnetically induced transparency, EIT) in a quantum-dot-molecule dielectric film. The tunable on- and off-resonance tunneling effect of an incident electromagnetic wave (probe field) through such a quantum-coherent quantum-dot-molecule dielectric film is investigated. It is found that a high gate voltage can lead to the EIT phenomenon of the quantum-dot-molecular systems. Under the condition of on-resonance light tunneling through the present quantum-dot-molecule dielectric film, the probe field should propagate without loss if the probe frequency detuning is zero. Such an effect caused by both EIT and resonant tunneling, which is sensitive to the gate voltage, can be utilized for designing devices such as photonic switching, transistors, and logic gates.

  2. Breaking the Carnot limit without violating the second law: A thermodynamic analysis of off-resonant quantum light generation

    NASA Astrophysics Data System (ADS)

    Boukobza, E.; Ritsch, H.

    2013-06-01

    The Carnot limit, formulated in 1824, represents the maximal efficiency of a classical heat engine. In this work we present a thermodynamical analysis of a light amplifier based on a three-level atom coupled off-resonantly to a single quantized cavity mode and to two heat reservoirs with positive temperatures. Based on standard work and heat flow equilibrium, we show that for a cavity blue-detuned with respect to the atomic resonance, the system can surpass the Carnot limit. Nevertheless, the second law of thermodynamics is still obeyed, as the total entropy always increases. By analyzing a semiclassical version of the model, we derive a formula for the critical frequency for which the Carnot limit is broken and a formula for the amplifier efficiency which agrees with its quantum counterpart. In the semiclassical regime, however, the second law is not satisfied and hence it does not offer a physically acceptable description of the system. Finally, we show that breaking the Carnot limit occurs also in a blue-detuned quantum amplifier with output coupling, which represents a realistic model of a laser or maser.

  3. Bottom-up study of the MRI positive contrast created by the Off-Resonance Saturation sequence

    NASA Astrophysics Data System (ADS)

    Delangre, S.; Vuong, Q. L.; Henrard, D.; Po, C.; Gallez, B.; Gossuin, Y.

    2015-05-01

    Superparamagnetic iron oxide nanoparticles (SPM particles) are used in MRI to highlight regions such as tumors through negative contrast. Unfortunately, sources as air bubbles or tissues interfaces also lead to negative contrast, which complicates the image interpretation. New MRI sequences creating positive contrast in the particle surrounding, such as the Off-Resonance Saturation sequence (ORS), have thus been developed. However, a theoretical study of the ORS sequence is still lacking, which hampers the optimization of this sequence. For this reason, this work provides a self-consistent analytical expression able to predict the dependence of the contrast on the sequence parameters and the SPM particles properties. This expression was validated by numerical simulations and experiments on agarose gel phantoms on a 11.7 T scanner system. It provides a fundamental understanding of the mechanisms leading to positive contrast, which could allow the improvement of the sequence for future in vivo applications. The influence of the SPM particle relaxivities, the SPM particle concentration, the echo time and the saturation pulse parameters on the contrast were investigated. The best contrast was achieved with SPM particles possessing the smallest transverse relaxivity, an optimal particle concentration and for low echo times.

  4. Improvement of the Off-Resonance Saturation, an MRI sequence for positive contrast with SPM particles: Theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Delangre, S.; Vuong, Q. L.; Po, C.; Gallez, B.; Gossuin, Y.

    2016-04-01

    The SuperParaMagnetic particles (SPM particles) are used as contrast agents in MRI and produce negative contrast with conventional T2 or T2∗-weighted sequences. Unfortunately, the SPM particle detection on images acquired with such sequences is sometimes difficult because negative contrast can be created by artifacts such as air bubbles or calcification. To overcome this problem, new sequences as Off-Resonance Saturation (ORS) were developed to produce positive contrast with SPM particles. This work explores a new way to optimize the contrast generated by the ORS sequence by increasing the number of saturation pulses applied before the imaging sequence. This modified sequence is studied with numerical simulations and experiments on agarose gel phantoms. A theoretical model able to predict the contrast for different values of the sequence parameters is also developed. The results show that the contrast increases with the saturation pulses number with an optimal value of three saturation pulses in order to avoid artifacts and limit the Specific Absorption Rate (SAR) effect. The dependence of the contrast on the SPM particle concentration and sequence parameters is comparable to what was observed for the ORS sequence.

  5. Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

    SciTech Connect

    Palneedi, Haribabu; Maurya, Deepam; Priya, Shashank; Kim, Gi-Yeop; Choi, Si-Young; Kang, Suk-Joong L.; Kim, Kwang-Ho; Ryu, Jungho

    2015-07-06

    A highly dense, 4 μm-thick Pb(Zr,Ti)O{sub 3} (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.

  6. 13C metabolic flux analysis in complex systems.

    PubMed

    Zamboni, Nicola

    2011-02-01

    Experimental determination of in vivo metabolic rates by methods of (13)C metabolic flux analysis is a pivotal approach to unravel structure and regulation of metabolic networks, in particular with microorganisms grown in minimal media. However, the study of real-life and eukaryotic systems calls for the quantification of fluxes also in cellular compartments, rich media, cell-wide metabolic networks, dynamic systems or single cells. These scenarios drastically increase the complexity of the task, which is only partly dealt by existing approaches that rely on rigorous simulations of label propagation through metabolic networks and require multiple labeling experiments or a priori information on pathway inactivity to simplify the problem. Albeit qualitative and largely driven by human interpretation, statistical analysis of measured (13)C-patterns remains the exclusive alternative to comprehensively handle such complex systems. In the future, this practice will be complemented by novel modeling frameworks to assay particular fluxes within a network by stable isotopic tracer for targeted validation of well-defined hypotheses.

  7. Glucogenesis in an insect, Manduca sexta L., estimated from the 13C isotopomer distribution in trehalose synthesized from [1,3-13C2]glycerol.

    PubMed

    Thompson, S N

    1997-07-19

    Glucogenesis from [3-13C]alanine and [1,3-13C2]glycerol was demonstrated in the insect Manduca sexta by examining the 13C enrichment of trehalose, a non-reducing disaccharide of glucose synthesized in the insect fat body and released into the blood or hemolymph. In insects maintained on a low carbohydrate diet, trehalose synthesized from [3-13C]alanine was selectively enriched at C1 and C6, and C2 and C5. The 13C-labelling pattern indicated the carboxylation of [3-13C]pyruvate, formed by transamination of the [3-13C]alanine followed by randomization of the label at the fumarate step of the tricarboxylic acid cycle and glucose synthesis via the gluconeogenic pathway. 13C enrichment of trehalose was absent in similarly maintained insect larvae administered 3-mercaptopicolinic acid, an inhibitor of hepatic phosphoenolpyruvate carboxykinase. Insects on the low carbohydrate diet also synthesized trehalose from [1,3-13C2]glycerol. 13C multiplets were observed in trehalose C3 and C4 demonstrating the synthesis of three 13C enriched glucose isotopomers from the 13C-labelled glycerol. The relative contributions of 13C-labelled glycerol and unlabelled 3 carbon substrates to the synthesis of the 13C enriched trehalose isotopomers were determined from the multiplet structure at C3, and calculation of minimal rates of glucogenesis were based on the 13C enrichment of C4. The C4/C3 13C enrichment ratio in trehalose synthesized from [1,3-13C2]glycerol was close to unity, and total glucogenesis was calculated after estimation of the expected contribution of unlabelled trehalose synthesis from 3 carbon substrates by comparison of the ratio of unlabelled and labelled contributions to the 13C enriched trehalose isotopomers with the 13C enrichment of [1,3-13C2]glycerol-3-phosphate. The estimated total rates of glucogenesis varied from 0.33 to 2.80 micromol glucose/g fresh weight/h. The blood sugar level of M. sexta was also highly variable. Although the potential importance of

  8. Spectral density mapping at multiple magnetic fields suitable for 13C NMR relaxation studies

    NASA Astrophysics Data System (ADS)

    Kadeřávek, Pavel; Zapletal, Vojtěch; Fiala, Radovan; Srb, Pavel; Padrta, Petr; Přecechtělová, Jana Pavlíková; Šoltésová, Mária; Kowalewski, Jozef; Widmalm, Göran; Chmelík, Josef; Sklenář, Vladimír; Žídek, Lukáš

    2016-05-01

    Standard spectral density mapping protocols, well suited for the analysis of 15N relaxation rates, introduce significant systematic errors when applied to 13C relaxation data, especially if the dynamics is dominated by motions with short correlation times (small molecules, dynamic residues of macromolecules). A possibility to improve the accuracy by employing cross-correlated relaxation rates and on measurements taken at several magnetic fields has been examined. A suite of protocols for analyzing such data has been developed and their performance tested. Applicability of the proposed protocols is documented in two case studies, spectral density mapping of a uniformly labeled RNA hairpin and of a selectively labeled disaccharide exhibiting highly anisotropic tumbling. Combination of auto- and cross-correlated relaxation data acquired at three magnetic fields was applied in the former case in order to separate effects of fast motions and conformational or chemical exchange. An approach using auto-correlated relaxation rates acquired at five magnetic fields, applicable to anisotropically moving molecules, was used in the latter case. The results were compared with a more advanced analysis of data obtained by interpolation of auto-correlated relaxation rates measured at seven magnetic fields, and with the spectral density mapping of cross-correlated relaxation rates. The results showed that sufficiently accurate values of auto- and cross-correlated spectral density functions at zero and 13C frequencies can be obtained from data acquired at three magnetic fields for uniformly 13C -labeled molecules with a moderate anisotropy of the rotational diffusion tensor. Analysis of auto-correlated relaxation rates at five magnetic fields represents an alternative for molecules undergoing highly anisotropic motions.

  9. The natural abundance of 13C with different agricultural management by NIRS with fibre optic probe technology.

    PubMed

    Fuentes, Mariela; González-Martín, Inmaculada; Hernández-Hierro, Jose Miguel; Hidalgo, Claudia; Govaerts, Bram; Etchevers, Jorge; Sayre, Ken D; Dendooven, Luc

    2009-06-30

    In the present study the natural abundance of (13)C is quantified in agricultural soils in Mexico which have been submitted to different agronomic practices, zero and conventional tillage, retention of crop residues (with and without) and rotation of crops (wheat and maize) for 17 years, which have influenced the physical, chemical and biological characteristics of the soil. The natural abundance of C13 is quantified by near infrared spectra (NIRS) with a remote reflectance fibre optic probe, applying the probe directly to the soil samples. Discriminate partial least squares analysis of the near infrared spectra allowed to classify soils with and without residues, regardless of the type of tillage or rotation systems used with a prediction rate of 90% in the internal validation and 94% in the external validation. The NIRS calibration model using a modified partial least squares regression allowed to determine the delta(13)C in soils with or without residues, with multiple correlation coefficients 0.81 and standard error prediction 0.5 per thousand in soils with residues and 0.92 and 0.2 per thousand in soils without residues. The ratio performance deviation for the quantification of delta(13)C in soil was 2.5 in soil with residues and 3.8 without residues. This indicated that the model was adequate to determine the delta(13)C of unknown soils in the -16.2 per thousand to -20.4 per thousand range. The development of the NIR calibration permits analytic determinations of the values of delta(13)C in unknown agricultural soils in less time, employing a non-destructive method, by the application of the fibre optic probe of remote reflectance to the soil sample.

  10. Measuring changes in substrate utilization in the myocardium in response to fasting using hyperpolarized [1-13C]butyrate and [1-13C]pyruvate

    PubMed Central

    Bastiaansen, Jessica A. M.; Merritt, Matthew E.; Comment, Arnaud

    2016-01-01

    Cardiac dysfunction is often associated with a shift in substrate preference for ATP production. Hyperpolarized (HP) 13C magnetic resonance spectroscopy (MRS) has the unique ability to detect real-time metabolic changes in vivo due to its high sensitivity and specificity. Here a protocol using HP [1-13C]pyruvate and [1-13C]butyrate is used to measure carbohydrate versus fatty acid metabolism in vivo. Metabolic changes in fed and fasted Sprague Dawley rats (n = 36) were studied at 9.4 T after tail vein injections. Pyruvate and butyrate competed for acetyl-CoA production, as evidenced by significant changes in [13C]bicarbonate (−48%), [1-13C]acetylcarnitine (+113%), and [5-13C]glutamate (−63%), following fasting. Butyrate uptake was unaffected by fasting, as indicated by [1-13C]butyrylcarnitine. Mitochondrial pseudoketogenesis facilitated the labeling of the ketone bodies [1-13C]acetoacetate and [1-13C]β-hydroxybutyryate, without evidence of true ketogenesis. HP [1-13C]acetoacetate was increased in fasting (250%) but decreased during pyruvate co-injection (−82%). Combining HP 13C technology and co-administration of separate imaging agents enables noninvasive and simultaneous monitoring of both fatty acid and carbohydrate oxidation. This protocol illustrates a novel method for assessing metabolic flux through different enzymatic pathways simultaneously and enables mechanistic studies of the changing myocardial energetics often associated with disease. PMID:27150735

  11. /sup 13/C NMR studies of the molecular flexibility of antidepressants

    SciTech Connect

    Munro, S.L.; Andrews, P.R.; Craik, D.J.; Gale, D.J.

    1986-02-01

    The solution dynamics of a series of clinically potent antidepressants have been investigated by measuring /sup 13/C NMR relaxation parameters. Correlation times and internal motional rates were calculated from spin-lattice relaxation times and nuclear Overhauser effects for the protonated carbons in mianserin, imipramine-like antidepressants, and amitriptyline-like antidepressants. These data were interpreted in terms of overall molecular tumbling, internal rotations, and inherent flexibility of these structures. Of particular interest was the conformational variability of the tricyclic nucleus of the tricyclic antidepressants, where the data indicated a fivefold difference in mobility of the dimethylene bridge of imipramine-like antidepressants relative to amitriptyline-like compounds. The implications of such a difference in internal motions is discussed in relation to previous NMR studies and to the reported differences in pharmacological activity of these antidepressants.

  12. The effect of sample hydration on 13C CPMAS NMR spectra of fulvic acids

    USGS Publications Warehouse

    Hatcher, P.G.; Wilson, M.A.

    1991-01-01

    Three fulvic acids, two of which have been well studied by a number of other groups (Armadale and Suwannee river fulvic acids) have been examined by high resolution solid-state 13C-NMR techniques to delineate the effect of absorbed water. Two main effects of absorbed water were observed: (1) changes in spin lattice relaxation times in the rotating frame and cross polarization times and (2) total loss of signal so that some fulvic acid is effectively in solution. These results suggest that discrepancies in the literature concerning observed relative signal intensities from different structural groups are due to absorbed water and emphasize the necessity for proper precautionary drying before spectroscopic analysis. ?? 1991.

  13. 13C-NMR in Iodine and Potassium Intercalated C60 Solid

    NASA Astrophysics Data System (ADS)

    Maniwa, Yutaka; Shibata, Takayuki; Mizoguchi, Kenji; Kume, Kiyoshi; Kikuchi, Koichi; Ikemoto, Isao; Suzuki, Shinzo; Achiba, Yoji

    1992-07-01

    Iodine intercalated C60, I2.29C60, was studied by 13C NMR above 160 K. A sharp NMR signal and a strong temperature-dependent spin-lattice relaxation time, T1, indicated a presence of C60 molecular rotation much higher than 10 kHz at least down to 160 K. No evidence of metallic characteristics was found in the NMR shift (143± 1 ppm) and the T1 (40± 5 sec at room temperature). In K3C60, metallic behavior, T1T˜constant, was observed at the carbon sites between 20 K and 100 K. Electronic density of states at the Fermi level, N(EF), in I2.29C60 was estimated to be smaller than 0.12 of that in K3C60, assuming a relationship between N(EF) and T1T for normal metals.

  14. 13C Metabolomics: NMR and IROA for Unknown Identification

    PubMed Central

    Clendinen, Chaevien S.; Stupp, Gregory S.; Wang, Bing; Garrett, Timothy J.; Edison, Arthur S.

    2016-01-01

    Abstract: Background Isotopic Ratio Outlier Analysis (IROA) is an untargeted metabolomics method that uses stable isotopic labeling and LC-HRMS for identification and relative quantification of metabolites in a biological sample under varying experimental conditions. Objective We demonstrate a method using high-sensitivity 13C NMR to identify an unknown metabolite isolated from fractionated material from an IROA LC-HRMS experiment. Methods IROA samples from the nematode Caenorhabditis elegans were fractionated using LC-HRMS using 5 repeated injections and collecting 30 sec fractions. These were concentrated and analyzed by 13C NMR. Results We isotopically labeled samples of C. elegans and collected 2 adjacent LC fractions. By HRMS, one contained at least 2 known metabolites, phenylalanine and inosine, and the other contained tryptophan and an unknown feature with a monoisotopic mass of m/z 380.0742 [M+H]+. With NMR, we were able to easily verify the known compounds, and we then identified the spin system networks responsible for the unknown resonances. After searching the BMRB database and comparing the molecular formula from LC-HRMS, we determined that the fragments were a modified anthranilate and a glucose modified by a phosphate. We then performed quantum chemical NMR chemical shift calculations to determine the most likely isomer, which was 3’-O-phospho-β-D-glucopyranosyl-anthranilate. This compound had previously been found in the same organism, validating our approach. Conclusion We were able to dereplicate previously known metabolites and identify a metabolite that was not in databases by matching resonances to NMR databases and using chemical shift calculations to determine the correct isomer. This approach is efficient and can be used to identify unknown compounds of interest using the same material used for IROA. PMID:28090435

  15. Prospective Work for Alma: the Millimeterwave and Submillimeterwave Spectrum of 13C-GLYCOLALDEHYDE

    NASA Astrophysics Data System (ADS)

    Haykal, Imane; Margulès, Laurent; Huet, Therese R.; Motiyenko, Roman; Guillemin, J.-C.

    2011-06-01

    Glycolaldehyde has been identified in interstellar sources. The relative abundance ratios of the three isomers (acetic acid) : (glycolaldehyde) : (methylformate) were estimated . The detection of 13C_1 and 13C_2 isotopomers of methylformate has been recently reported in Orion, as a result of the detailled labororatory spectroscopic study. Therefore the spectroscopy of the 13C isotopomers of glycolaldehyde is investigated in laboratory in order to provide data for an astronomical search. The instrument ALMA will certainly be a good instrument to detect them. Up to now, only the microwave spectra of 13CH_2OH-CHO and of CH_2OH-13CHO have been observed several years ago in the 12-40 GHz range. Spectra of both species are presently recorded in Lille in the 150-950 GHz range with the new submillimetre-wave spectrometer based on harmonic generation of a microwave synthesizer source, using only solid-state devices, and coupled to a cell of 2.2 m length The absolute accuracy of the line positions is better than 30 KHz. The rotational structure of the ground state and of the three first excited vibrational states has been observed. Two 13C enriched samples were used. The analysis is in progress. This work is supported by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS) and by the contract ANR-08-BLAN-0054 J. M. Hollis, S. N. Vogel, L. E. Snyder, et al., Astrophys. J. 554(2001) L81 R. A. H. Butler, F. C. De Lucia, D. T Petkie, et al., Astrophys. J. Supp. 134 (2001) 319 M. T. Beltran, C. Codella, S. Viti, R. Niri, R. Cesaroni, Astrophys. J. 690 (2009) L93. M. Carjaval, L. Margulès, B. Tercero et al., Astron. Astrophys. 500 (2009) 1109. K.-M. Marstokk and H. Møllendal, J. Mol. Struct. 16 (1973) 259. R. A. Motiyenko, L. Margulès, E. A. Alekseev et al., J. Mol. Spectrosc. 264 (2010) 94.

  16. Impact of field strength and iron oxide nanoparticle concentration on the linearity and diagnostic accuracy of off-resonance imaging.

    PubMed

    Farrar, Christian T; Dai, Guangping; Novikov, Mikhail; Rosenzweig, Anthony; Weissleder, Ralph; Rosen, Bruce R; Sosnovik, David E

    2008-06-01

    Off-resonance imaging (ORI) techniques are being increasingly used to image iron oxide imaging agents such as monocrystalline iron oxide nanoparticles (MION). However, the diagnostic accuracy, linearity, and field dependence of ORI have not been fully characterized. In this study, the sensitivity, specificity, and linearity of ORI were thus examined as a function of both MION concentration and magnetic field strength (4.7 and 14 T). MION phantoms with and without an air interface as well as MION uptake in a mouse model of healing myocardial infarction were imaged. MION-induced resonance shifts were shown to increase linearly with MION concentration. In contrast, the ORI signal/sensitivity was highly non-linear, initially increasing with MION concentration until T2 became comparable to the TE and decreasing thereafter. The specificity of ORI to distinguish MION-induced resonance shifts from on-resonance water was found to decrease with increasing field because of the increased on-resonance water linewidths (15 Hz at 4.7 T versus 45 Hz at 14 T). Large resonance shifts ( approximately 300 Hz) were observed at air interfaces at 4.7 T, both in vitro and in vivo, and led to poor ORI specificity for MION concentrations less than 150 microg Fe/mL. The in vivo ORI sensitivity was sufficient to detect the accumulation of MION in macrophages infiltrating healing myocardial infarcts, but the specificity was limited by non-specific areas of positive contrast at the air/tissue interfaces of the thoracic wall and the descending aorta. Improved specificity and linearity can, however, be expected at lower fields where decreased on-resonance water linewidths, reduced air-induced resonance shifts, and longer T2 relaxation times are observed. The optimal performance of ORI will thus likely be seen at low fields, with moderate MION concentrations and with sequences containing very short TEs.

  17. The First in Vivo Observation of 13C- 15N Coupling in Mammalian Brain

    NASA Astrophysics Data System (ADS)

    Kanamori, Keiko; Ross, Brian D.

    2001-12-01

    [5-13C,15N]Glutamine, with 1J(13C-15N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by 13C MRS at 4.7 T. The brain [5-13C]glutamine peak consisted of the doublet from [5-13C,15N]glutamine and the center [5-13C,14N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-13C,15N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-13C,15N]glutamine was formed by glial uptake of released neurotransmitter [5-13C]glutamate and its reaction with 15NH3 catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively13C-enriched by intravenous [2,5-13C]glucose infusion to 13C-label whole-brain glutamate C5, followed by [12C]glucose infusion to chase 13C from the small and rapidly turning-over glial glutamate pool, leaving 13C mainly in the neurotransmitter [5-13C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-13C,15N]glutamine arises from a coupling between 13C of neuronal origin and 15N of glial origin. Measurement of the rate of brain [5-13C,15N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

  18. Effects of Off-Resonance Irradiation, Cross-Relaxation, and Chemical Exchange on Steady-State Magnetization and Effective Spin-Lattice Relaxation Times

    NASA Astrophysics Data System (ADS)

    Kingsley, Peter B.; Monahan, W. Gordon

    2000-04-01

    In the presence of an off-resonance radiofrequency field, recovery of longitudinal magnetization to a steady state is not purely monoexponential. Under reasonable conditions with zero initial magnetization, recovery is nearly exponential and an effective relaxation rate constant R1eff = 1/T1eff can be obtained. Exact and approximate formulas for R1eff and steady-state magnetization are derived from the Bloch equations for spins undergoing cross-relaxation and chemical exchange between two sites in the presence of an off-resonance radiofrequency field. The relaxation formulas require that the magnetization of one spin is constant, but not necessarily zero, while the other spin relaxes. Extension to three sites with one radiofrequency field is explained. The special cases of off-resonance effects alone and with cross-relaxation or chemical exchange, cross-relaxation alone, and chemical exchange alone are compared. The inaccuracy in saturation transfer measurements of exchange rate constants by published formulas is discussed for the creatine kinase reaction.

  19. Probing the effect of charge transfer enhancement in off resonance mode SERS via conjugation of the probe dye between silver nanoparticles and metal substrates.

    PubMed

    Selvakannan, Pr; Ramanathan, Rajesh; Plowman, Blake J; Sabri, Ylias M; Daima, Hemant K; O'Mullane, Anthony P; Bansal, Vipul; Bhargava, Suresh K

    2013-08-21

    The charge transfer-mediated surface enhanced Raman scattering (SERS) of crystal violet (CV) molecules that were chemically conjugated between partially polarized silver nanoparticles and optically smooth gold and silver substrates has been studied under off-resonant conditions. Tyrosine molecules were used as a reducing agent to convert silver ions into silver nanoparticles where oxidised tyrosine caps the silver nanoparticle surface with its semiquinone group. This binding through the quinone group facilitates charge transfer and results in partially oxidised silver. This establishes a chemical link between the silver nanoparticles and the CV molecules, where the positively charged central carbon of CV molecules can bind to the terminal carboxylate anion of the oxidised tyrosine molecules. After drop casting Ag nanoparticles bound with CV molecules it was found that the free terminal amine groups tend to bind with the underlying substrates. Significantly, only those CV molecules that were chemically conjugated between the partially polarised silver nanoparticles and the underlying gold or silver substrates were found to show SERS under off-resonant conditions. The importance of partial charge transfer at the nanoparticle/capping agent interface and the resultant conjugation of CV molecules to off resonant SERS effects was confirmed by using gold nanoparticles prepared in a similar manner. In this case the capping agent binds to the nanoparticle through the amine group which does not facilitate charge transfer from the gold nanoparticle and under these conditions SERS enhancement in the sandwich configuration was not observed.

  20. Anisotropy of electron-phonon interaction in nanoscale CdSe platelets as seen via off-resonant and resonant Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Cherevkov, S. A.; Fedorov, A. V.; Artemyev, M. V.; Prudnikau, A. V.; Baranov, A. V.

    2013-07-01

    The off-resonant and resonant Raman spectra of optical phonons in colloidal CdSe nanoplatelets (NPLs) with the thickness of 4, 5, and 6 CdSe monolayers are analyzed. These spectra are dominated by SO and LO phonon bands of CdSe whose frequencies are thickness independent in the off-resonant Raman but demonstrate evident thickness dependence similar to that observed for confined optical phonons in CdSe quantum dots in the resonant Raman. The results show that conventional optical phonons propagating along the NPL lateral planes contribute mainly to the off-resonant Raman while confined optical phonons propagating in the perpendicular direction dominate the Raman spectra excited in the resonance with confined exciton transitions of CdSe NPLs. An anisotropic electron-phonon interaction is proposed to be responsible for this effect in the CdSe NPLs. A formation of Cd-S monolayer on the surface of CdSe NPLs treated by thiol-containing ligands is also detected in Raman spectra.

  1. Reaction cross sections for. nu. sup 13 C r arrow e sup minus sup 13 N and. nu. sup 13 C r arrow. nu. prime sup 13 C sup * for low energy neutrinos

    SciTech Connect

    Fukugita, M. ); Kohyama, Y.; Kubodera, K.; Kuramoto, T. )

    1990-04-01

    Cross sections for {nu}+{sup 13}C reactions are calculated both for charged- and neutral-current reactions in order to estimate the efficiency of a {sup 13}C target as a solar neutrino detector. The relevant transition matrix elements are obtained using the semiphenomenological effective-operator approach for {ital p}-shell nuclei.

  2. Experimental evidence of E × B plasma rotation in a 2.45 GHz hydrogen discharge

    SciTech Connect

    Cortázar, O. D.; Tarvainen, O.; Koivisto, H.

    2015-12-15

    An experimental observation of a rotating plasma structure in a 2.45 GHz microwave-driven hydrogen discharge is reported. The rotation is presumably produced by E × B drift. The formation of the rotating plasma structure is sensitive to the strength of the off-resonance static magnetic field. The rotation frequency is on the order of 10 kHz and is affected by the neutral gas pressure and applied microwave power.

  3. LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

    NASA Astrophysics Data System (ADS)

    Stepanov, E. V.

    2002-11-01

    Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

  4. PASADENA hyperpolarization of 13C biomolecules: equipment design and installation

    PubMed Central

    Hövener, Jan-Bernd; Chekmenev, Eduard Y.; Harris, Kent C.; Perman, William H.; Robertson, Larry W.; Bhattacharya, Pratip

    2009-01-01

    Object The PASADENA method has achieved hyperpolarization of 16–20% (exceeding 40,000-fold signal enhancement at 4.7 T), in liquid samples of biological molecules relevant to in vivo MRI and MRS. However, there exists no commercial apparatus to perform this experiment conveniently and reproducibly on the routine basis necessary for translation of PASADENA to questions of biomedical importance. The present paper describes equipment designed for rapid production of six to eight liquid samples per hour with high reproducibility of hyperpolarization. Materials and methods Drawing on an earlier, but unpublished, prototype, we provide diagrams of a delivery circuit, a laminar-flow reaction chamber within a low field NMR contained in a compact, movable housing. Assembly instructions are provided from which a computer driven, semiautomated PASADENA polarizer can be constructed. Results Together with an available parahydrogen generator, the polarizer, which can be operated by a single investigator, completes one cycle of hyperpolarization each 52 s. Evidence of efficacy is presented. In contrast to competing, commercially available devices for dynamic nuclear polarization which characteristically require 90 min per cycle, PASADENA provides a low-cost alternative for high throughput. Conclusions This equipment is suited to investigators who have an established small animal NMR and wish to explore the potential of heteronuclear (13C and 15N) MRI, MRS, which harnesses the enormous sensitivity gain offered by hyperpolarization. PMID:19067008

  5. New optical analyzer for 13C-breath test

    NASA Astrophysics Data System (ADS)

    Harde, Hermann; Dressler, Matthias; Helmrich, Günther; Wolff, Marcus; Groninga, Hinrich

    2008-04-01

    Medical breath tests are well established diagnostic tools, predominantly for gastroenterological inspections, but also for many other examinations. Since the composition and concentration of exhaled volatile gases reflect the physical condition of a patient, a breath analysis allows one to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that is based on photoacoustic spectroscopy and uses a DFB diode laser at 2.744 μm. The concentration ratio of the CO II isotopologues is determined by measuring the absorption on a 13CO II line in comparison to a 12CO II line. In the specially selected spectral range the lines have similar strengths, although the concentrations differ by a factor of 90. Therefore, the signals are well comparable. Due to an excellent signal-noise-ratio isotope variations of less than 1% can be resolved as required for the breath test.

  6. Millimeter and submillimeter wave spectra of mono-13C-acetaldehydes

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Ilyushin, V. V.; Guillemin, J. C.

    2015-07-01

    Context. The acetaldehyde molecule is ubiquitous in the interstellar medium of our galaxy, and due to its dense and complex spectrum, large dipole moment, and several low-lying torsional states, acetaldehyde is considered to be a "weed" molecule for radio astronomy observations. Mono-13C acetaldehydes 13CH3CHO and CH313CHO are likely to be identified in astronomical surveys, such as those available with the very sensitive ALMA telescope. Laboratory measurements and analysis of the millimeter and submillimeter-wave spectra are the prerequisites for the successful radioastronomical search for the new interstellar molecular species, as well as for new isotopologs of already detected interstellar molecules. Aims: In this context, to provide reliable predictions of 13CH3CHO and CH313CHO spectra in millimeter and submillimeter wave ranges, we study rotational spectra of these species in the frequency range from 50 to 945 GHz. Methods: The spectra of mono-13C acetaldehydes were recorded using the spectrometer based on Schottky-diode frequencymultiplication chains in the Lille laboratory. The rotational spectra of 13CH3CHO and CH313CHO molecules were analyzed using the Rho axis method. Results: In the recorded spectra we have assigned 6884 for the 13CH3CHO species and 6458 for CH313CHO species new rotational transitions belonging to the ground, first, and second excited torsional states. These measurements were fitted together with previously published data to the Hamiltonian models that use 91 and 87 parameters to achieve overall weighted rms deviations 0.88 for the 13CH3CHO species and 0.95 for CH313CHO. On the basis of the new spectroscopic results, predictions of transition frequencies in the frequency range up to 1 THz with J ≤ 60 and Ka ≤ 20 are presented for both isotopologs. Full Tables 3-6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/579/A46

  7. Accurate measurements of {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    SciTech Connect

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Nielsen, Niels Chr.; Khaneja, Navin

    2014-09-21

    Application of sets of {sup 13}C-{sup 13}C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ({sup 13}C′) and aliphatic ({sup 13}C{sub aliphatic}) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly {sup 13}C,{sup 15}N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of {sup 13}C′-{sup 13}C{sub aliphatic} distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform {sup 13}C,{sup 15}N-labeling on the FGAIL fragment.

  8. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  9. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  10. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  11. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  12. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  13. Enhancing the [13C]bicarbonate signal in cardiac hyperpolarized [1-13C]pyruvate MRS studies by infusion of glucose, insulin and potassium.

    PubMed

    Lauritzen, Mette Hauge; Laustsen, Christoffer; Butt, Sadia Asghar; Magnusson, Peter; Søgaard, Lise Vejby; Ardenkjær-Larsen, Jan Henrik; Åkeson, Per

    2013-11-01

    A change in myocardial metabolism is a known effect of several diseases. MRS with hyperpolarized (13)C-labelled pyruvate is a technique capable of detecting changes in myocardial pyruvate metabolism, and has proven to be useful for the evaluation of myocardial ischaemia in vivo. However, during fasting, the myocardial glucose oxidation is low and the fatty acid oxidation (β-oxidation) is high, which complicates the interpretation of pyruvate metabolism with the technique. The aim of this study was to investigate whether the infusion of glucose, insulin and potassium (GIK) could increase the myocardial glucose oxidation in the citric acid cycle, reflected as an increase in the [(13)C]bicarbonate signal in cardiac hyperpolarized [1-(13)C]pyruvate MRS measurements in fasted rats. Two groups of rats were infused with two different doses of GIK and investigated by MRS after injection of hyperpolarized [1-(13)C]pyruvate. No [(13)C]bicarbonate signal could be detected in the fasted state. However, a significant increase in the [(13)C]bicarbonate signal was observed by the infusion of a high dose of GIK. This study demonstrates that a high [(13)C]bicarbonate signal can be achieved by GIK infusion in fasted rats. The increased [(13)C]bicarbonate signal indicates an increased flux of pyruvate through the pyruvate dehydrogenase enzyme complex and an increase in myocardial glucose oxidation through the citric acid cycle.

  14. 13C nuclear magnetic resonance data of lanosterol derivatives—Profiling the steric topology of the steroid skeleton via substituent effects on its 13C NMR

    NASA Astrophysics Data System (ADS)

    Dias, Jerry Ray; Gao, Hongwu

    2009-12-01

    The 13C NMR spectra of over 24 tetracyclic triterpenoid derivatives have been structurally analyzed. The 13C NMR chemical shifts allow one to probe the steric topology of the rigid steroid skeleton and inductive effects of its substituents. Use of deuterium labeling in chemical shift assignment and B-ring aromatic terpenoids are also featured.

  15. Geochemical Approach to Archaeal Ecology: δ13C of GDGTs

    NASA Astrophysics Data System (ADS)

    Lichtin, S.; Warren, C.; Pearson, A.; Pagani, M.

    2015-12-01

    Over the last decade and a half, glycerol dialkyl glycerol tetraethers (GDGTs) have increasingly been used to reconstruct environmental temperatures; proxies like TEX86 that correlate the relative abundance of these archaeal cell membrane lipids to sea surface temperature are omnipresent in paleoclimatology literature. While it has become common to make claims about past temperatures using GDGTs, our present understanding of the organisms that synthesize the compounds is still quite limited. The generally accepted theory states that microorganisms like the Thaumarchaeota modify the structure of membrane lipids to increase intermolecular interactions, strengthening the membrane at higher temperatures. Yet to date, culture experiments have been largely restricted to a single species, Nitrosopumilus maritimes, and recent studies on oceanic archaeal rRNA have revealed that these biomarkers are produced in diverse, heterogeneous, and site-specific communities. This brings up questions as to whether different subclasses of GDGTs, and all subsequent proxies, represent adaptation within a single organismal group or a shift in community composition. To investigate whether GDGTs with different chain structures, from the simple isoprenoidal GDGT-0 to Crenarchaeol with its many cyclopentane groups, are sourced from archaea with similar or disparate metabolic pathways—and if that information is inherited in GDGTs trapped in marine sediments—this study examines the stable carbon isotope values (δ13C) of GDGTs extracted from the uppermost meters of sediment in the Orca Basin, Gulf of Mexico, using spooling-wire microcombustion isotope-ratio mass spectrometer (SWiM-IRMS), tackling a fundamental assumption of the TEX86 proxy that influences the way we perceive the veracity of existing temperature records.

  16. NOTE The effect of 13C enrichment in the glassing matrix on dynamic nuclear polarization of [1-13C]pyruvate

    NASA Astrophysics Data System (ADS)

    Lumata, Lloyd; Kovacs, Zoltan; Malloy, Craig; Sherry, A. Dean; Merritt, Matthew

    2011-03-01

    Dimethyl sulfoxide (DMSO) can effectively form a glassy matrix necessary for dynamic nuclear polarization (DNP) experiments. We tested the effects of 13C enrichment in DMSO on DNP of [1-13C]pyruvate doped with trityl radical OX063Me. We found that the polarization build-up time τ of pyruvate in 13C-labeled DMSO glassing solution is twice as fast as the unenriched DMSO while the nuclear magnetic resonance enhancement was unchanged. This indicates that 13C-13C spin diffusion is a limiting factor in the kinetics of DNP in this system, but it has a minimal effect on the absolute value of polarization achievable for the target.

  17. The effect of 13C enrichment in the glassing matrix on dynamic nuclear polarization of [1-13C]pyruvate

    NASA Astrophysics Data System (ADS)

    Lumata, Lloyd; Kovacs, Zoltan; Malloy, Craig; Sherry, A. Dean; Merritt, Matthew

    2011-03-01

    Dimethyl sulfoxide (DMSO) can effectively form a glassy matrix necessary for dynamic nuclear polarization (DNP) experiments. We tested the effects of 13C enrichment in DMSO on DNP of [1-13C]pyruvate doped with trityl radical OX063Me. We found that the polarization build-up time τ of pyruvate in 13C-labeled DMSO glassing solution is twice as fast as the unenriched DMSO while the nuclear magnetic resonance enhancement was unchanged. This indicates that 13C-13C spin diffusion is a limiting factor in the kinetics of DNP in this system, but it has a minimal effect on the absolute value of polarization achievable for the target.

  18. The use of 13C labeling to enhance the sensitivity of 13C solid-state CPMAS NMR to study polymorphism in low dose solid formulations.

    PubMed

    Booy, Kees-Jan; Wiegerinck, Peter; Vader, Jan; Kaspersen, Frans; Lambregts, Dorette; Vromans, Herman; Kellenbach, Edwin

    2005-02-01

    (13)C labeling was used to enhance the sensitivity of (13)C solid-state NMR to study the effect of tabletting on the polymorphism of a steroidal drug. The steroidal drug Org OD 14 was (13)C labeled and formulated into tablets containing only 0.5-2.5% active ingredient. The tablets were subsequently studied by solid-state (13)C CPMAS NMR. The crystalline form present in tablets could readily be analyzed in tablets. No change in crystalline form was observed as a result of formulation or in subsequent stability studies. Solid-state NMR in combination with (13)C labeling can, in suitable cases, be used as a strategy to study the effect of formulation on the polymorphism of low dose drugs.

  19. BEBEtr and BUBI: J-compensated concurrent shaped pulses for 1H-13C experiments

    NASA Astrophysics Data System (ADS)

    Ehni, Sebastian; Luy, Burkhard

    2013-07-01

    Shaped pulses designed for broadband excitation, inversion and refocusing are important tools in modern NMR spectroscopy to achieve robust pulse sequences especially in heteronuclear correlation experiments. A large variety of mostly computer-optimized pulse shapes exist for different desired bandwidths, available rf-field strengths, and tolerance to B1-inhomogeneity. They are usually derived for a single spin 1/2, neglecting evolution due to J-couplings. While pulses with constant resulting phase are selfcompensated for heteronuclear coupling evolution as long as they are applied exclusively on a single nucleus, the situation changes for concurrently applied pulse shapes. Using the example of a 1H,13C two spin system, two J-compensated pulse pairs for the application in INEPT-type transfer elements were optimized: a point-to-point pulse sandwich called BEBEtr, consisting of a broadband excitation and time-reversed excitation pulse, and a combined universal rotation and point-to-point pulse pair called BUBI, which acts as a refocusing pulse on 1H and a corresponding inversion pulse on 13C. After a derivation of quality factors and optimization protocols, a theoretical and experimental comparison with conventionally derived BEBOP, BIBOP, and BURBOP-180° pulses is given. While the overall transfer efficiency of a single pulse pair is only reduced by approximately 0.1%, resulting transfer to undesired coherences is reduced by several percent. In experiments this can lead to undesired phase distortions for pairs of uncompensated pulse shapes and even differences in signal intensities of 5-10% in HSQC and up to 68% in more complex COB-HSQC experiments.

  20. Methods for metabolic evaluation of prostate cancer cells using proton and 13C HR-MAS spectroscopy and [3-13C] pyruvate as a metabolic substrate

    PubMed Central

    Levin, Yakir S.; Albers, Mark J.; Butler, Thomas N.; Spielman, Daniel; Peehl, Donna M.; Kurhanewicz, John

    2009-01-01

    Prostate cancer has been shown to undergo unique metabolic changes associated with neoplastic transformation, with associated changes in citrate, alanine, and lactate concentrations. 13C HR-MAS spectroscopy provides an opportunity to simultaneously investigate the metabolic pathways implicated in these changes by using 13C labeled substrates as metabolic probes. In this work, a method to reproducibly interrogate metabolism in prostate cancer cells in primary culture was developed using HR-MAS spectroscopy. Optimization of cell culture protocols, labeling parameters, harvesting, storage, and transfer was performed. Using [3-13C] pyruvate as a metabolic probe, 1H and 13C HR-MAS spectroscopy were used to quantify the net amount and fractional enrichment of several labeled metabolites that evolved in multiple cell samples from each of five different prostate cancers. Average enrichment across all cancers was 32.4±5.4% for [3-13C] alanine, 24.5±5.4% for [4-13C] glutamate, 9.1±2.5% for [3-13C] glutamate, 25.2±5.7% for [3-13C] aspartate, and 4.2±1.0% for [3-13C] lactate. Cell samples from the same parent population demonstrated reproducible fractional enrichments of alanine, glutamate, and aspartate to within 12%, 10%, and 10%, respectively. Furthermore, the cells produced a significant amount of [4-13C] glutamate, which supports the bioenergetic theory for prostate cancer. These methods will allow further characterization of metabolic properties of prostate cancer cells in the future. PMID:19780158

  1. Determination of fructose metabolic pathways in normal and fructose-intolerant children: A sup 13 C NMR study using (U- sup 13 C)fructose

    SciTech Connect

    Gopher, A.; Lapidot, A. ); Vaisman, N. ); Mandel, H. )

    1990-07-01

    An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-(U-{sup 13}C)fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of {sup 13}C NMR spectra of plasma glucose. Significantly lower values ({approx}3-fold) for fructose conversion to glucose were obtained for the HFI patients as compared to the controls. A quantitative determination of the metabolic pathways of fructose conversion to glucose was derived from {sup 13}C NMR measurement of plasma ({sup 13}C)glucose isotopomer populations. The finding of isotopomer populations of three adjacent {sup 13}C atoms at glucose C-4 ({sup 13}C{sub 3}-{sup 13}C{sub 4}-{sup 13}C{sub 5}) suggests that there is a direct pathway from fructose, by-passing fructose-1-phosphate aldolase, to fructose 1,6-bisphosphate. The metabolism of fructose by fructose-1-phosphate aldolase activity accounts for only {approx}50% of the total amount of hepatic fructose conversion to glucose. In view of the marked decline by 67% in synthesis of glucose from fructose in HFI subjects found in this study, the extent of ({sup 13}C)glucose formation from a trace amount of (U-{sup 13}C)fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism.

  2. Synthesis and solid-state NMR structural characterization of 13C-labeled graphite oxide.

    PubMed

    Cai, Weiwei; Piner, Richard D; Stadermann, Frank J; Park, Sungjin; Shaibat, Medhat A; Ishii, Yoshitaka; Yang, Dongxing; Velamakanni, Aruna; An, Sung Jin; Stoller, Meryl; An, Jinho; Chen, Dongmin; Ruoff, Rodney S

    2008-09-26

    The detailed chemical structure of graphite oxide (GO), a layered material prepared from graphite almost 150 years ago and a precursor to chemically modified graphenes, has not been previously resolved because of the pseudo-random chemical functionalization of each layer, as well as variations in exact composition. Carbon-13 (13C) solid-state nuclear magnetic resonance (SSNMR) spectra of GO for natural abundance 13C have poor signal-to-noise ratios. Approximately 100% 13C-labeled graphite was made and converted to 13C-labeled GO, and 13C SSNMR was used to reveal details of the chemical bonding network, including the chemical groups and their connections. Carbon-13-labeled graphite can be used to prepare chemically modified graphenes for 13C SSNMR analysis with enhanced sensitivity and for fundamental studies of 13C-labeled graphite and graphene.

  3. Local deposition of 13C tracer in the JET MKII-HD divertor

    NASA Astrophysics Data System (ADS)

    Likonen, Jari; Airila, M. I.; Coad, J. P.; Hakola, A.; Koivuranta, S.; Ahonen, E.; Alves, E.; Barradas, N.; Widdowson, A.; Rubel, M.; Brezinsek, S.; Groth, M.; JET-EFDA Contributors

    2013-07-01

    Migration and deposition of 13C have been investigated at JET by injecting 13C-labelled methane at the outer divertor base at the end of the 2009 campaign. The 13C deposition profile was measured with enhanced proton scattering (EPS) and secondary ion mass spectrometry (SIMS) techniques. A strong toroidal deposition band for 13C was observed experimentally on each of the analysed four outer divertor floor tiles. In addition, 13C was also found on the vertical edge of load bearing tile (LBT) and at the bottom of the LBT tile facing the puffing hole. Local 13C migration in the vicinity of the injection location was modelled by the ERO code. The ERO simulations also produced the strong toroidal 13C deposition band but there is strong deposition also on the vertical edge of the LBT tile and elsewhere on the horizontal part of the outer divertor floor tile.

  4. Propionate metabolism in the rat heart by 13C n.m.r. spectroscopy.

    PubMed Central

    Sherry, A D; Malloy, C R; Roby, R E; Rajagopal, A; Jeffrey, F M

    1988-01-01

    High-resolution 13C n.m.r. spectroscopy has been used to examine propionate metabolism in the perfused rat heart. A number of tricarboxylic acid (TCA) cycle intermediates are observable by 13C n.m.r. in hearts perfused with mixtures of pyruvate and propionate. When the enriched 13C-labelled nucleus originates with pyruvate, the resonances of the intermediates appear as multiplets due to formation of multiply-enriched 13C-labelled isotopomers, whereas when the 13C-labelled nucleus originates with propionate, these same intermediates appear as singlets in the 13C spectrum since entry of propionate into the TCA cycle occurs via succinyl-CoA. An analysis of the isotopomer populations in hearts perfused with [3-13C]pyruvate plus unlabelled propionate indicates that about 27% of the total pyruvate pool available to the heart is derived directly from unlabelled propionate. This was substantiated by perfusing a heart for 2 h with [3-13C]propionate as the only available exogenous substrate. Under these conditions, all of the propionate consumed by the heart, as measured by conventional chemical analysis, ultimately entered the oxidative pathway as [2-13C] or [3-13C]pyruvate. This is consistent with entry of propionate into the TCA cycle intermediate pools as succinyl-CoA and concomitant disposal of malate to pyruvate via the malic enzyme. 13C resonances arising from enriched methylmalonate and propionylcarnitine are also detected in hearts perfused with [3-13C] or [1-13C]propionate which suggests that 13C n.m.r. may be useful as a non-invasive probe in vivo of metabolic abnormalities involving the propionate pathway, such as methylmalonic aciduria or propionic acidaemia. PMID:3178775

  5. Characterization of uniformly and atom-specifically 13C-labeled heparin and heparan sulfate polysaccharide precursors using 13C NMR spectroscopy and ESI mass spectrometry

    PubMed Central

    Nguyen, Thao K. N.; Tran, Vy M.; Victor, Xylophone V.; Skalicky, Jack J.; Kuberan, Balagurunathan

    2010-01-01

    The biological actions of heparin and heparan sulfate, two structurally related glycosaminoglycans, depend on the organization of the complex heparanome. Due to the structural complexity of the heparanome, the sequence of variably sulfonated uronic acid and glucosamine residues is usually characterized by the analysis of smaller oligosaccharide and disaccharide fragments. Even characterization of smaller heparin/heparan sulfate oligosaccharide or disaccharide fragments using simple 1D 1H NMR spectroscopy is often complicated by the extensive signal overlap. 13C NMR signals, on the other hand, overlap less and therefore, 13C NMR spectroscopy can greatly facilitate the structural elucidation of the complex heparanome and provide finer insights into the structural basis for biological functions. This is the first report of the preparation of anomeric carbon-specific 13C-labeled heparin/heparan sulfate precursors from the Escherichia coli K5 strain. Uniformly 13C- and 15N-labeled precursors were also produced and characterized by 13C NMR spectroscopy. Mass spectrometric analysis of enzymatically fragmented disaccharides revealed that anomeric carbon-specific labeling efforts resulted in a minor loss/scrambling of 13C in the precursor backbone, whereas uniform labeling efforts resulted in greater than 95% 13C isotope enrichment in the precursor backbone. These labeled precursors provided high-resolution NMR signals with great sensitivity and set the stage for studying the heparanome–proteome interactions. PMID:20832774

  6. 13C MRS of Human Brain at 7 Tesla Using [2-13C]Glucose Infusion and Low Power Broadband Stochastic Proton Decoupling

    PubMed Central

    Li, Shizhe; An, Li; Yu, Shao; Araneta, Maria Ferraris; Johnson, Christopher S.; Wang, Shumin; Shen, Jun

    2015-01-01

    Purpose 13C magnetic resonance spectroscopy (MRS) of human brain at 7 Tesla (T) may pose patient safety issues due to high RF power deposition for proton decoupling. The purpose of present work is to study the feasibility of in vivo 13C MRS of human brain at 7 T using broadband low RF power proton decoupling. Methods Carboxylic/amide 13C MRS of human brain by broadband stochastic proton decoupling was demonstrated on a 7 T scanner. RF safety was evaluated using the finite-difference time-domain method. 13C signal enhancement by nuclear Overhauser effect (NOE) and proton decoupling was evaluated in both phantoms and in vivo. Results At 7 T, the peak amplitude of carboxylic/amide 13C signals was increased by a factor of greater than 4 due to the combined effects of NOE and proton decoupling. The 7 T 13C MRS technique used decoupling power and average transmit power of less than 35 W and 3.6 W, respectively. Conclusion In vivo 13C MRS studies of human brain can be performed at 7 T well below the RF safety threshold by detecting carboxylic/amide carbons with broadband stochastic proton decoupling. PMID:25917936

  7. Benzenium ion chemistry on solid metal halide superacids: in situ {sup 13}C NMR experiments and theoretical calculations

    SciTech Connect

    Xu, T.; Barich, D.H.; Torres, P.D.; Haw, J.F.

    1997-01-15

    The benzenium, toluenium, and ethylbenzenium ions were synthesized on aluminium bromide by coadsorption of the precursors with either HBr or alkyl bromide. Principal components of the {sup 13}C chemical shift tensors for the ring carbons of these species were measured from magic angle spinning spectra. The benzenium ion was static at 77 K but underwent both proton scrambling and anisotropic rotation at 298 K as well as oligomerization at higher loadings. The para form of the toluenium ion was the dominant isomer at 77 K, but a temperature-dependent equilibrium between the para and ortho isomers was observed at 273 K. The energy calculations at MP4(fc,sdq)/ 6-311+G{sup *}//MP2/6-311+G{sup *} with thermal corrections resulted in good agreement between calculated and measured proton affinities for benzene, toluene, and ethylbenzene. For toluenium ion, the energies of the ortho and meta isomers were 1.2 and 5.4 kcal/mol, respectively, above the para isomer, consistent with the temperature-dependent {sup 13}C NMR spectra in the solid state. {sup 13}C chemical shift tensors calculated at the GIAO-MP2/tzp/dz//MP2/ 6-311+G{sup *} and GIAO-MP2/tzp/dz//B3LYP/6-311+G{sup *} levels of theory were in very close agreement with each other and generally in satisfactory agreement with experimental principal components. 64 refs., 8 figs., 4 tabs.

  8. Slow-down of 13C spin diffusion in organic solids by fast MAS: a CODEX NMR Study.

    PubMed

    Reichert, D; Bonagamba, T J; Schmidt-Rohr, K

    2001-07-01

    One- and two-dimensional 13C exchange nuclear magnetic resonance experiments under magic-angle spinning (MAS) can provide detailed information on slow segmental reorientations and chemical exchange in organic solids, including polymers and proteins. However, observations of dynamics on the time scale of seconds or longer are hampered by the competing process of dipolar 13C spin exchange (spin diffusion). In this Communication, we show that fast MAS can significantly slow down the dipolar spin exchange effect for unprotonated carbon sites. The exchange is measured quantitatively using the centerband-only detection of exchange technique, which enables the detection of exchange at any spinning speed, even in the absence of changes of isotropic chemical shifts. For chemically equivalent unprotonated 13C sites, the dipolar spin exchange rate is found to decrease slightly less than proportionally with the sample-rotation frequency, between 8 and 28 kHz. In the same range, the dipolar spin exchange rate for a glassy polymer with an inhomogeneously broadened MAS line decreases by a factor of 10. For methylene groups, no or only a minor slow-down of the exchange rate is found.

  9. Differential protonation and dynamic structure of doxylamine succinate in solution using 1H and 13C NMR.

    PubMed

    Somashekar, B S; Nagana Gowda, G A; Ramesha, A R; Khetrapal, C L

    2004-07-01

    A protonation and dynamic structural study of doxylamine succinate, a 1:1 salt of succinic acid with dimethyl-[2-(1-phenyl-1-pyridin-2-yl-ethoxy)ethyl]amine, in solution using one- and two-dimensional 1H and 13C NMR experiments at variable temperature and concentration is presented. The two acidic protons of the salt doxylamine succinate are in 'intermediate' exchange at room temperature, as evidenced by the appearance of a broad signal. This signal evolves into two distinct signals below about -30 degrees C. A two-dimensional 1H-1H double quantum filtered correlation experiment carried out at -55 degrees C shows protonation of one of the acidic protons to the dimethylamine nitrogen. A two-dimensional rotating frame 1H-1H NOE experiment at the same temperature reveals that the other proton remains with the succinate moiety. Comparison of the 1H and 13C chemical shifts and the 13C T1 relaxation times of the salt with those of the free base further substantiate the findings.

  10. 13C metabolic flux analysis at a genome-scale.

    PubMed

    Gopalakrishnan, Saratram; Maranas, Costas D

    2015-11-01

    Metabolic models used in 13C metabolic flux analysis generally include a limited number of reactions primarily from central metabolism. They typically omit degradation pathways, complete cofactor balances, and atom transition contributions for reactions outside central metabolism. This study addresses the impact on prediction fidelity of scaling-up mapping models to a genome-scale. The core mapping model employed in this study accounts for (75 reactions and 65 metabolites) primarily from central metabolism. The genome-scale metabolic mapping model (GSMM) (697 reaction and 595 metabolites) is constructed using as a basis the iAF1260 model upon eliminating reactions guaranteed not to carry flux based on growth and fermentation data for a minimal glucose growth medium. Labeling data for 17 amino acid fragments obtained from cells fed with glucose labeled at the second carbon was used to obtain fluxes and ranges. Metabolic fluxes and confidence intervals are estimated, for both core and genome-scale mapping models, by minimizing the sum of square of differences between predicted and experimentally measured labeling patterns using the EMU decomposition algorithm. Overall, we find that both topology and estimated values of the metabolic fluxes remain largely consistent between core and GSM model. Stepping up to a genome-scale mapping model leads to wider flux inference ranges for 20 key reactions present in the core model. The glycolysis flux range doubles due to the possibility of active gluconeogenesis, the TCA flux range expanded by 80% due to the availability of a bypass through arginine consistent with labeling data, and the transhydrogenase reaction flux was essentially unresolved due to the presence of as many as five routes for the inter-conversion of NADPH to NADH afforded by the genome-scale model. By globally accounting for ATP demands in the GSMM model the unused ATP decreased drastically with the lower bound matching the maintenance ATP requirement. A non

  11. Origin of the conformational modulation of the 13C NMR chemical shift of methoxy groups in aromatic natural compounds.

    PubMed

    Toušek, Jaromír; Straka, Michal; Sklenář, Vladimír; Marek, Radek

    2013-01-24

    The interpretation of nuclear magnetic resonance (NMR) parameters is essential to understanding experimental observations at the molecular and supramolecular levels and to designing new and more efficient molecular probes. In many aromatic natural compounds, unusual (13)C NMR chemical shifts have been reported for out-of-plane methoxy groups bonded to the aromatic ring (~62 ppm as compared to the typical value of ~56 ppm for an aromatic methoxy group). Here, we analyzed this phenomenon for a series of aromatic natural compounds using Density Functional Theory (DFT) calculations. First, we checked the methodology used to optimize the structure and calculate the NMR chemical shifts in aromatic compounds. The conformational effects of the methoxy group on the (13)C NMR chemical shift then were interpreted by the Natural Bond Orbital (NBO) and Natural Chemical Shift (NCS) approaches, and by excitation analysis of the chemical shifts, breaking down the total nuclear shielding tensor into the contributions from the different occupied orbitals and their magnetic interactions with virtual orbitals. We discovered that the atypical (13)C NMR chemical shifts observed are not directly related to a different conjugation of the lone pair of electrons of the methoxy oxygen with the aromatic ring, as has been suggested. Our analysis indicates that rotation of the methoxy group induces changes in the virtual molecular orbital space, which, in turn, correlate with the predominant part of the contribution of the paramagnetic deshielding connected with the magnetic interactions of the BD(CMet-H)→BD*(CMet-OMet) orbitals, resulting in the experimentally observed deshielding of the (13)C NMR resonance of the out-of-plane methoxy group.

  12. Pentose cycling and the distribution of 13C in trehalose during glucogenesis from 13C-labelled substrates in an insect.

    PubMed

    Thompson, S N; Scales, V M; Bochardt, D B

    1995-07-26

    Redistribution of 13C in trehalose (Tre) due to pentose cycling was observed in vivo in Manduca sexta during glucogenesis from [3-13C]alanine (Ala) and [2-13C]glycerol (Gly). The extent of cycling was affected by dietary composition. Larvae maintained on a low-carbohydrate diet (LCD) exhibited approximately 13% cycling, while those on a complete-balanced diet (CBD) or low-fat diet (LFD) displayed much higher rates of cycling. Significant incorporation of 13C via reversal of the non-oxidative phase was evident on all diets but was greatest on the CBD and LFD. In contrast to conclusions from previous studies with insects, the present results indicate that under normal conditions the pentose pathway is not the principal source of triose phosphates for oxidative catabolism during larval development.

  13. Isotopic 13C NMR spectrometry to assess counterfeiting of active pharmaceutical ingredients: site-specific 13C content of aspirin and paracetamol.

    PubMed

    Silvestre, Virginie; Mboula, Vanessa Maroga; Jouitteau, Catherine; Akoka, Serge; Robins, Richard J; Remaud, Gérald S

    2009-10-15

    Isotope profiling is a well-established technique to obtain information about the chemical history of a given compound. However, the current methodology using IRMS can only determine the global (13)C content, leading to the loss of much valuable data. The development of quantitative isotopic (13)C NMR spectrometry at natural abundance enables the measurement of the (13)C content of each carbon within a molecule, thus giving simultaneous access to a number of isotopic parameters. When it is applied to active pharmaceutical ingredients, each manufactured batch can be characterized better than by IRMS. Here, quantitative isotopic (13)C NMR is shown to be a very promising and effective tool for assessing the counterfeiting of medicines, as exemplified by an analysis of aspirin (acetylsalicylic acid) and paracetamol (acetaminophen) samples collected from pharmacies in different countries. It is proposed as an essential complement to (2)H NMR and IRMS.

  14. Metabolic pathways for ketone body production. /sup 13/C NMR spectroscopy of rat liver in vivo using /sup 13/C-multilabeled fatty acids

    SciTech Connect

    Pahl-Wostl, C.; Seelig, J.

    1986-11-04

    The hormonal regulation of ketogenesis in the liver of living rat has been studied noninvasively with /sup 13/C nuclear magnetic resonance. The spatial selection for the liver was better than 90%, with extrahepatic adipose tissue contribution only a very small amount of signal. The metabolic activities of the liver were investigated by infusion of /sup 13/C-labeled butyrate in the jugular vein of the anesthetized rat. The rate of butyrate infusion was chosen to be close to the maximum oxidative capacity of the rat liver, and the /sup 13/C signal intensities were enhanced by using doubly labeled (1,3-/sup 13/C)butyrate as a substrate. Different /sup 13/C NMR spectra and hence different metabolites were observed depending on the hormonal state of the animal. The /sup 13/C NMR studies demonstrate that even when rate of acetyl-CoA production are high, the disposal of this compound is not identical in fasted and diabetic animals. This supports previous suggestions that the redox state of the mitochondrion represents the most important factor in regulation. For a given metabolic state of the animal, different signal intensities were obtained depending on whether butyrate was labeled at C-1, C-3, or C-1,3. From the ratios of incorporation of /sup 13/C label into the carbons of 3-hydroxybutyrate, it could be estimated that a large fraction of butyrate evaded ..beta..-oxidation to acetyl-CoA but was converted directly to acetoacetyl-CoA. /sup 13/C-labeled glucose could be detected in vivo in the liver of diabetic rats.

  15. Off-resonance nutation nuclear magnetic resonance study of framework aluminosilicate glasses with Li, Na, K, Rb or Cs as charge-balancing cation.

    PubMed

    Dirken, P J; Nachtegaal, G H; Kentgens, A P

    1995-11-01

    Framework aluminosilicate glasses with varying charge-balancing cation (Li, Na, K, Rb and Cs) have been studied with 27Al and 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) and 27Al on-resonance and off-resonance nutation NMR spectroscopy. This first application of off-resonance nutation NMR to disordered samples proves that it is a promising technique for the determination of mean quadrupole interactions in amorphous systems. Linewidths for Al decrease systematically with increasing size of the cation, due to a decrease in the quadrupole interaction from 5.0 MHz for the Li glass to 2.8 MHz for the Cs glass. A simple point-charge model effectively predicts the decrease in the quadrupole interaction. This indicates that the alkali ion is located close to aluminum. Looking at the residual linewidth after subtraction of the quadrupole broadening, the Al chemical shift distribution does not change significantly with the type of alkali ion. The same is true for the observed Si linewidth.

  16. The resonant, near-resonant, and off-resonant plasmon coupling effects for the bonding modes in two types of asymmetric dimer

    NASA Astrophysics Data System (ADS)

    Li, Quanshui; Hu, Jianling; Wang, Ziya; Wang, Fengping; Bao, Yongjun

    2014-07-01

    The resonant, near-resonant, and off-resonant plasmon coupling effects for the bonding modes in asymmetric dimers are illustrated by two types of configuration, one formed by a gold nanoparticle and a TiO2-Ag core-shell nanoparticle and the other formed by two TiO2-Ag core-shell nanoparticles with suitable sizes. The redshift and blueshift behaviours of the coupled bonding modes with decreasing gap are found under longitudinal and transverse polarization of light for these dimers in the resonant situation, respectively. Under the near-resonant situation, the redshift behaviours of the coupled bonding modes still remain under longitudinal polarization, whereas the two separated modes of monomers after coupling under transverse polarization exhibit no obvious peak-shift behaviours, and the one on the lower frequency side shows an apparent attenuation in the strength. Under the off-resonant situation, the redshift behaviours not only occur in the coupled modes under longitudinal polarization, but also occur in two separated modes under transverse polarization.

  17. Off-resonance R1rho relaxation outside of the fast exchange limit: an experimental study of a cavity mutant of T4 lysozyme.

    PubMed

    Korzhnev, Dmitry M; Orekhov, Vladislav Yu; Dahlquist, Frederick W; Kay, Lewis E

    2003-05-01

    An (15)N off-resonance R(1rho) spin relaxation study of an L99A point mutant of T4 lysozyme is presented. Previous CPMG-based relaxation dispersion studies of exchange in this protein have established that the molecule interconverts between a populated ground state and an excited state (3.4%) with an exchange rate constant of 1450 s(-1) at 25 degrees C. It is shown that for the majority of residues in this protein the offset dependence of the R(1rho) relaxation rates cannot be well fit using models which are only valid in the fast exchange regime. In contrast, a recently derived expression by Trott and Palmer (J. Magn. Reson., 154, 157-160, 2002) which is valid over a wider window of exchange than other relations, is shown to fit the data well. Values of (signed) chemical shift differences between exchanging sites have been extracted and are in reasonable agreement with shift differences measured using CPMG methods. A set of simulations is presented which help establish the exchange regimes that are best suited to analysis by off-resonance R(1rho) techniques.

  18. Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.

    PubMed

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S

    2013-07-25

    Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results.

  19. A 13C NMR spectrometric method for the determination of intramolecular δ13C values in fructose from plant sucrose samples.

    PubMed

    Gilbert, Alexis; Silvestre, Virginie; Robins, Richard J; Tcherkez, Guillaume; Remaud, Gérald S

    2011-07-01

    Recent developments in (13) C NMR spectrometry have allowed the determination of intramolecular (13) C/(12) C ratios with high precision. However, the analysis of carbohydrates requires their derivatization to constrain the anomeric carbon. Fructose has proved to be particularly problematic because of a byproduct occurring during derivatization and the complexity of the NMR spectrum of the derivative. Here, we describe a method to determine the intramolecular (13) C/(12) C ratios in fructose by (13) C NMR analysis of the acetyl-isopropylidene derivative. We have applied this method to measure the intramolecular (13) C/(12) C distribution in the fructosyl moiety of sucrose and have compared this with that in the glucosyl moiety. Three prominent features stand out. First, in sucrose from both C(3) and C(4) plants, the C-1 and C-2 positions of the glucosyl and fructosyl moieties are markedly different. Second, these positions in C(3) and C(4) plants show a similar profile. Third, the glucosyl and fructosyl moieties of sucrose from Crassulacean acid metabolism (CAM) metabolism have a different profile. These contrasting values can be interpreted as a result of the isotopic selectivity of enzymes that break or make covalent bonds in glucose metabolism, whereas the distinctive (13) C pattern in CAM sucrose probably indicates a substantial contribution of gluconeogenesis to glucose synthesis.

  20. Biosynthesis of highly enriched 13C-lycopene for human metabolic studies using repeated batch tomato cell culturing with 13C-glucose.

    PubMed

    Moran, Nancy Engelmann; Rogers, Randy B; Lu, Chi-Hua; Conlon, Lauren E; Lila, Mary Ann; Clinton, Steven K; Erdman, John W

    2013-08-15

    While putative disease-preventing lycopene metabolites are found in both tomato (Solanum lycopersicum) products and in their consumers, mammalian lycopene metabolism is poorly understood. Advances in tomato cell culturing techniques offer an economical tool for generation of highly-enriched (13)C-lycopene for human bioavailability and metabolism studies. To enhance the (13)C-enrichment and yields of labelled lycopene from the hp-1 tomato cell line, cultures were first grown in (13)C-glucose media for three serial batches and produced increasing proportions of uniformly labelled lycopene (14.3±1.2%, 39.6±0.5%, and 48.9±1.5%) with consistent yields (from 5.8 to 9 mg/L). An optimised 9-day-long (13)C-loading and 18-day-long labelling strategy developed based on glucose utilisation and lycopene yields, yielded (13)C-lycopene with 93% (13)C isotopic purity, and 55% of isotopomers were uniformly labelled. Furthermore, an optimised acetone and hexane extraction led to a fourfold increase in lycopene recovery from cultures compared to a standard extraction.

  1. 13C CP/MAS NMR studies of vitamin E model compounds.

    PubMed

    Witkowski, Stanislaw; Paradowska, Katarzyna; Wawer, Iwona

    2004-10-01

    13C cross-polarization magic angle spinning (CP/MAS) NMR data for 2,2,5,7,8-pentamethylchroman-6-ol (2), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox c) (3) and its acetate (4), 2-methoxy-2,2,5,7,8-pentamethylchroman-6-ol (5), 2-hydroxy-2,2,5,7,8-pentamethylchroman-6-ol (6) and 2,2,5,7,8-pentamethylchroman (7) are reported. A deshielding of 7.7 ppm for the carboxylic carbon was observed in solid Trolox due to formation of intermolecular hydrogen bonds within cyclic dimers. Such crystal packing permits effective cross-polarization and fast relaxation (short T1rho(H)). The impact of the proton concentration on the CP dynamics is reflected by the longer T(CP) and T1rhoH for Trolox-d2 (deuterated at mobile proton sites). The calculated GIAO RHF shielding constants are sensitive to intramolecular effects: rotation around the C-6-O bond (changes of sigma up to 8 ppm) and conformation at C-2.

  2. Thz Spectroscopy of Acetaldehyde and Search of 13C Species in Orion

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Ilyushin, V. V.; Tercero, B.; Cernicharo, J.; Guillemin, J.-C.

    2012-06-01

    Acetaldehyde (CH_3CHO) is one of the high priority complex organic molecules for the astrophysical community. There is a lack of data concerning the 13C species since the measurements are limited to 40 GHz up to date. This molecule displays a large amplitude motion: the hindered rotation of the methyl group with respect to the rest of the molecule. The analysis is performed with RAM36 code which used the Rho Axis Method. Last year we presented the analysis of the millimeterwave spectra of the 13CH_3CHO species. We extended the analysis to the THz range of the vibrational ground state for both species. We are also analyzing the first torsional state (≈140 cm-1) for two reasons: first, this permits to remove correlation between parameters. Second, this state contribute to the partition function even at ISM temperature (100--150 K) since there is an influence on the column density determined in case of detection. The searches of these isotopomers are in progress in ORION. This work was supported by the CNES and the Action sur Projets de l'INSU, PCMI. This work was also done under the ANR-08-BLAN-0054. Kilb, R.W.; Lin, C.C.; and Wilson, E.B. J. Chem. Phys. 26, (1957) 1695 Ilyushin, V.V. et al J. Mol. Spectrosc. 259, (2010) 26 Margules, L. et al. FA07, 66th International Symposium on Molecular Spectroscopy (2011)

  3. 13cRA regulates the differentiation of antler chondrocytes through targeting Runx3.

    PubMed

    Zhang, Hong-Liang; Cao, Hang; Yang, Zhan-Qing; Geng, Shuang; Wang, Kai; Yu, Hai-Fan; Guo, Bin; Yue, Zhan-Peng

    2017-03-01

    Although 13cRA is involved in the regulation of cellular proliferation and differentiation, its physiological roles in chondrocyte proliferation and differentiation still remain unknown. Here, we showed that 13cRA could induce the proliferation of sika deer antler chondrocytes and expression of Ccnd3 and Cdk6. Administration of 13cRA to antler chondrocytes resulted in an obvious increase in the expression of chondrocyte marker Col II and hypertrophic chondrocyte marker Col X. Silencing of Crabp2 expression by specific siRNA could prevent the 13cRA-induced up-regulation of Col X, whereas overexpression of Crabp2 showed the opposite effects. Further study found that Crabp2 mediated the regulation of 13cRA on the expression of Runx3 which was highly expressed in the antler cartilage and inhibited the differentiation of antler chondrocytes. Moreover, attenuation of Runx3 expression greatly raised 13cRA-induced chondrocyte differentiation. Simultaneously, 13cRA could stimulate the expression of Cyp26a1 and Cyp26b1 in the antler chondrocytes. Inhibition of Cyp26a1 and/or Cyp26b1 reinforced the effects of 13cRA on the expression of Col X and Runx3, while overexpression of Cyp26b1 rendered the antler chondrocytes hyposensitive to 13cRA. Collectively, 13cRA may play an important role in the differentiation of antler chondrocytes through targeting Runx3. Crabp2 enhances the effects of 13cRA on chondrocyte differentiation, while Cyp26a1 and Cyp26b1 weaken the sensitivity of antler chondrocytes to 13cRA.

  4. Synthesis of isotopically labeled R- or S-[.sup.13C, .sup.2H] glycerols

    DOEpatents

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

    2008-01-22

    The present invention is directed to asymmetric chiral labeled glycerols including at least one chiral atom, from one to two .sup.13C atoms and from zero to four deuterium atoms bonded directly to a carbon atom, e.g., (2S) [1,2-.sup.13C.sub.2]glycerol and (2R) [1,2-.sup.13C.sub.2]glycerol, and to the use of such chiral glycerols in the preparation of labeled amino acids.

  5. 13C-NOESY-HSQC with Split Carbon Evolution for Increased Resolution with Uniformly Labeled Proteins

    NASA Astrophysics Data System (ADS)

    Baur, Matthias; Gemmecker, Gerd; Kessler, Horst

    1998-06-01

    Two new pulse sequences are presented for the recording of 2D13C-HSQC and 3D13C-NOESY-HSQC experiments, containing two consecutive carbon evolution periods. The two periods are separated by az-filter which creates a clean CxHz-quantum state for evolution in the second period. Each period is incremented (in anon-constant-time fashion) only to the extent that the defocusing of carbon inphase magnetization throughJ-coupling with neighboring carbons remains insignificant. Therefore,13C homonuclearJ-couplings are rendered ineffective, reducing the loss of signal and peak splitting commonly associated with long13C evolution times. The two periods are incremented according to a special acquisition protocol employing a13C-13C gradient echo to yield a data set analogous to one obtained by evolution over the added duration of both periods. The spectra recorded with the new technique on uniformly13C-labeled proteins at twice the evolution time of the standard13C-HSQC experiment display a nearly twofold enhancement of resolution in the carbon domain, while maintaining a good sensitivity even in the case of large proteins. Applied to the IIAManprotein ofE. coli(31 kDa), the13C-HSQC experiment recorded with a carbon evolution time of 2 × 8 ms showed a 36% decrease in linewidths compared to the standard13C-HSQC experiment, and theS/Nratio of representative cross-peaks was reduced to 40%. This reduction reflects mostly the typical loss of intensity observed when recording with an increased resolution. The13C-NOESY-HSQC experiment derived from the13C-HSQC experiment yielded additional NOE restraints between resonances which previously had been unresolved.

  6. Lowest bending mode of 13C-substituted C3 and an experimentally derived structure

    NASA Astrophysics Data System (ADS)

    Breier, Alexander A.; Büchling, Thomas; Schnierer, Rico; Lutter, Volker; Fuchs, Guido W.; Yamada, Koichi M. T.; Mookerjea, Bhaswati; Stutzki, Jürgen; Giesen, Thomas F.

    2016-12-01

    The ν2 lowest bending mode of linear C3 and of all its 13C-substituted isotopologues was recorded using a terahertz-supersonic jet spectrometer in combination with a laser ablation source. Sixty-five ro-vibrational transitions between 1.8 and 1.9 THz have been assigned to linear 12C12C12C, 12C12C13, 12C13C12C, 13C13C12C, 13C12C13C, and 13C13C13. For each isotopologue, molecular parameters were obtained and the C-C-bond length was derived experimentally. All results are in excellent agreement with recent ab initio calculations [B. Schröder and P. Sebald, J. Chem. Phys. 144, 044307 (2016)]. The new measurements explain why the interstellar search for singly substituted 12C12C13C has failed so far. A spectral line list with recommended transition frequencies based on global data fits is given to foster future interstellar detections.

  7. Biokinetics of (13)C in the human body after oral administration of (13)C-labeled glucose as an index for the biokinetics of (14)C.

    PubMed

    Masuda, Tsuyoshi; Tako, Yasuhiro; Matsushita, Kensaku; Takeda, Hiroshi; Endo, Masahiro; Nakamura, Yuji; Hisamatsu, Shun'ichi

    2016-09-01

    The retention of (13)C in the human body after oral administration of (13)C-labeled glucose was studied in three healthy volunteer subjects to estimate the 50 year cumulative body burden for (13)C as an index of the committed dose of the radioisotope (14)C. After administration of (13)C-labeled glucose, the volunteers ingested controlled diets with a fixed number of calories for 112 d. Samples of breath and urine were collected up to 112 d after administration. Samples of feces were collected up to 14 d after administration. Hair samples were obtained at 119 d after administration and analyzed as a representative index of the rate of excretion of organic (13)C via pathways such as skin cell exfoliation and mucus secretion. All samples were analyzed for (13)C/(12)C atomic ratio to determine the rate of excretion via each pathway. We then constructed a metabolic model with a total of four pathways (breath, urine, feces, and other) comprising seven compartments. We determined the values of the biokinetic parameters in the model by using the obtained excretion data. From 74% to 94% of the (13)C administered was excreted in breath, whereas  <2% was excreted in urine and feces. In the other pathway, the excretion rate constant in the compartment with the longest residence time stretched to hundreds of days but the rate constant for each subject was not statistically significant (P value  >  0.1). In addition, the dataset for one of the three subjects was markedly different from those of the other two. When we estimated the 50 year cumulative body burden for (13)C by using our model and we included non-statistically significant parameters, a considerable cumulative body burden was found in the compartments excreting to the other pathway. Although our results on the cumulative body burden of (13)C from orally administered carbon as glucose were inconclusive, we found that the compartments excreting to the other pathway had a markedly long residence time and

  8. NMR crystallography to probe the breathing effect of the MIL-53(Al) metal-organic framework using solid-state NMR measurements of (13)C-(27)Al distances.

    PubMed

    Giovine, Raynald; Volkringer, Christophe; Trébosc, Julien; Amoureux, Jean Paul; Loiseau, Thierry; Lafon, Olivier; Pourpoint, Frédérique

    2017-03-01

    The metal-organic framework MIL-53(Al) (aluminium terephthalate) exhibits a structural transition between two porous structures with large pore (lp) or narrow pore (np) configurations. This transition, called the breathing effect, is observed upon changes in temperature or external pressure, as well as with the adsorption of guest molecules, such as H2O, within the pores. We show here how these different pore openings can be detected by observing the dephasing of (13)C magnetization under (13)C-(27)Al dipolar couplings using Rotational-Echo Saturation-Pulse Double-Resonance (RESPDOR) solid-state NMR experiments with Simultaneous Frequency and Amplitude Modulation (SFAM) recoupling. These double-resonance NMR experiments between (13)C and (27)Al nuclei, which have close Larmor frequencies, are feasible thanks to the use of a frequency splitter. The experimental SFAM-RESPDOR signal fractions agree well with those simulated from the MIL-53(Al)-lp and -np crystal structures obtained from powder X-ray diffraction analysis. Hence, these (13)C-(27)Al solid-state NMR experiments validate these structures and confirm their rigidity. A similar agreement is reported for the framework ligands in the as-synthesized (as) MIL-53(Al), in which the pores contain free ligands. Furthermore, in this case, (13)C-{(27)Al} SFAM-RESPDOR experiments allow an estimation of the average distance between the free ligands and the (27)Al nuclei of the framework.

  9. Photobioreactor design for isotopic non-stationary 13C-metabolic flux analysis (INST 13C-MFA) under photoautotrophic conditions.

    PubMed

    Martzolff, Arnaud; Cahoreau, Edern; Cogne, Guillaume; Peyriga, Lindsay; Portais, Jean-Charles; Dechandol, Emmanuel; Le Grand, Fabienne; Massou, Stéphane; Gonçalves, Olivier; Pruvost, Jérémy; Legrand, Jack

    2012-12-01

    Adaptive metabolic behavior of photoautotrophic microorganisms toward genetic and environmental perturbations can be interpreted in a quantitative depiction of carbon flow through a biochemical reaction network using isotopic non-stationary (13) C-metabolic flux analysis (INST (13) C-MFA). To evaluate (13) C-metabolic flux maps for Chlamydomonas reinhardtii, an original experimental framework was designed allowing rapid, reliable collection of high-quality isotopomer data against time. It involved (i) a short-time (13) C labeling injection device based on mixing control in a torus-shaped photobioreactor with plug-flow hydrodynamics allowing a sudden step-change in the (13) C proportion in the substrate feed and (ii) a rapid sampling procedure using an automatic fast filtration method coupled to a manual rapid liquid nitrogen quenching step. (13) C-substrate labeling enrichment was controlled through the total dissolved inorganic carbon concentration in the pulsed solution. First results were obtained from steady-state continuous culture measurements allowing the characterization of the kinetics of label incorporation into light-limited growing cells cultivated in a photobioreactor operating at the maximal biomass productivity for an incident photon flux density of 200 µmol m(-2) s(-1). (13)C label incorporation was measured for 21 intracellular metabolites using IC-MS/MS in 58 samples collected across a labeling experiment duration of 7 min. The fastest labeling rate was observed for 2/3-phosphoglycerate with an apparent isotopic stationary state reached after 300 s. The labeling rate was consistent with the optimized mixing time of about 4.9 s inside the reactor and the shortest reliable sampling period assessed at 5 s.

  10. The Nature of Carbonate and Organic δ13C Covariance Through Geological Time

    NASA Astrophysics Data System (ADS)

    Oehlert, A. M.; Swart, P. K.

    2014-12-01

    Significant evolutionary, climatic, and oceanographic events in Earth history are often accompanied by excursions in the carbon isotope composition (δ13C) of marine carbonates and co-occurring sedimentary organic material. The observation of synchronous excursions in the δ13C values of marine carbonates and coeval organic matter is commonly thought to prove that the deposit has not been altered by diagenesis, and that the variations in the δ13C records are the result of a significant change in global carbon cycling. Furthermore, this model suggests that the covariance of carbonate and organic δ13C records is driven only by changes in the δ13C value of the dissolved inorganic carbon in the surface waters of the ocean. However, recent work suggests that there may be at least two alternate models for generating covariance between carbonate and organic δ13C values in the geologic record. One of the models invokes sea-level driven syndepositional mixing between isotopically distinct sources of carbonate and organic material to produce positive covariance between carbonate and organic δ13C values. The second model suggests that post-depositional alteration to the carbonate δ13C values during meteoric diagenesis, in concert with concurrent contributions of terrestrial organic material during subaerial exposure, can also produce co-occurring negative excursions with tightly covariant δ13C records. In contrast to earlier interpretations of covariant δ13C values, these models suggest that both syndepositional and post-depositional factors can significantly influence the relationship between carbonate and organic δ13C values in a variety of depositional environments. The implications for reconstructions of ancient global carbon cycle events will be explored within the context of these three models, and their relative importance throughout geologic time will be discussed.

  11. Metabolism of hyperpolarized [1‐13C]pyruvate through alternate pathways in rat liver

    PubMed Central

    Moreno, Karlos X.; Wang, Jian‐Xiong; Fidelino, Leila; Merritt, Matthew E.; Sherry, A. Dean; Malloy, Craig R.

    2016-01-01

    The source of hyperpolarized (HP) [13C]bicarbonate in the liver during metabolism of HP [1‐13C]pyruvate is uncertain and likely changes with physiology. Multiple processes including decarboxylation through pyruvate dehydrogenase or pyruvate carboxylase followed by subsequent decarboxylation via phosphoenolpyruvate carboxykinase (gluconeogenesis) could play a role. Here we tested which metabolic fate of pyruvate contributed to the appearance of HP [13C]bicarbonate during metabolism of HP [1‐13C]pyruvate by the liver in rats after 21 h of fasting compared to rats with free access to food. The 13C NMR of HP [13C]bicarbonate was observed in the liver of fed rats, but not in fasted rats where pyruvate carboxylation and gluconeogenesis was active. To further explore the relative fluxes through pyruvate carboxylase versus pyruvate dehydrogenase in the liver under typical conditions of hyperpolarization studies, separate parallel experiments were performed with rats given non‐hyperpolarized [2,3‐13C]pyruvate. 13C NMR analysis of glutamate isolated from the liver of rats revealed that flux from injected pyruvate through pyruvate dehydrogenase was dominant under fed conditions whereas flux through pyruvate carboxylase dominated under fasted conditions. The NMR signal of HP [13C]bicarbonate does not parallel pyruvate carboxylase activity followed by subsequent decarboxylation reaction leading to glucose production. In the liver of healthy well‐fed rats, the appearance of HP [13C]bicarbonate exclusively reflects decarboxylation of HP [1‐13C]pyruvate via pyruvate dehydrogenase. © 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. PMID:26836042

  12. Metabolism of hyperpolarized [1-(13)C]pyruvate through alternate pathways in rat liver.

    PubMed

    Jin, Eunsook S; Moreno, Karlos X; Wang, Jian-Xiong; Fidelino, Leila; Merritt, Matthew E; Sherry, A Dean; Malloy, Craig R

    2016-04-01

    The source of hyperpolarized (HP) [(13)C]bicarbonate in the liver during metabolism of HP [1-(13)C]pyruvate is uncertain and likely changes with physiology. Multiple processes including decarboxylation through pyruvate dehydrogenase or pyruvate carboxylase followed by subsequent decarboxylation via phosphoenolpyruvate carboxykinase (gluconeogenesis) could play a role. Here we tested which metabolic fate of pyruvate contributed to the appearance of HP [(13)C]bicarbonate during metabolism of HP [1-(13)C]pyruvate by the liver in rats after 21 h of fasting compared to rats with free access to food. The (13)C NMR of HP [(13)C]bicarbonate was observed in the liver of fed rats, but not in fasted rats where pyruvate carboxylation and gluconeogenesis was active. To further explore the relative fluxes through pyruvate carboxylase versus pyruvate dehydrogenase in the liver under typical conditions of hyperpolarization studies, separate parallel experiments were performed with rats given non-hyperpolarized [2,3-(13)C]pyruvate. (13)C NMR analysis of glutamate isolated from the liver of rats revealed that flux from injected pyruvate through pyruvate dehydrogenase was dominant under fed conditions whereas flux through pyruvate carboxylase dominated under fasted conditions. The NMR signal of HP [(13)C]bicarbonate does not parallel pyruvate carboxylase activity followed by subsequent decarboxylation reaction leading to glucose production. In the liver of healthy well-fed rats, the appearance of HP [(13)C]bicarbonate exclusively reflects decarboxylation of HP [1-(13)C]pyruvate via pyruvate dehydrogenase.

  13. Robust hyperpolarized (13)C metabolic imaging with selective non-excitation of pyruvate (SNEP).

    PubMed

    Chen, Way Cherng; Teo, Xing Qi; Lee, Man Ying; Radda, George K; Lee, Philip

    2015-08-01

    In vivo metabolic imaging using hyperpolarized [1-(13)C]pyruvate provides localized biochemical information and is particularly useful in detecting early disease changes, as well as monitoring disease progression and treatment response. However, a major limitation of hyperpolarized magnetization is its unrecoverable decay, due not only to T1 relaxation but also to radio-frequency (RF) excitation. RF excitation schemes used in metabolic imaging must therefore be able to utilize available hyperpolarized magnetization efficiently and robustly for the optimal detection of substrate and metabolite activities. In this work, a novel RF excitation scheme called selective non-excitation of pyruvate (SNEP) is presented. This excitation scheme involves the use of a spectral selective RF pulse to specifically exclude the excitation of [1-(13)C]pyruvate, while uniformly exciting the key metabolites of interest (namely [1-(13)C]lactate and [1-(13)C]alanine) and [1-(13)C]pyruvate-hydrate. By eliminating the loss of hyperpolarized [1-(13)C]pyruvate magnetization due to RF excitation, the signal from downstream metabolite pools is increased together with enhanced dynamic range. Simulation results, together with phantom measurements and in vivo experiments, demonstrated the improvement in signal-to-noise ratio (SNR) and the extension of the lifetime of the [1-(13)C]lactate and [1-(13)C]alanine pools when compared with conventional non-spectral selective (NS) excitation. SNEP has also been shown to perform comparably well with multi-band (MB) excitation, yet SNEP possesses distinct advantages, including ease of implementation, less stringent demands on gradient performance, increased robustness to frequency drifts and B0 inhomogeneity as well as easier quantification involving the use of [1-(13)C]pyruvate-hydrate as a proxy for the actual [1-(13)C] pyruvate signal. SNEP is therefore a promising alternative for robust hyperpolarized [1-(13)C]pyruvate metabolic imaging with high

  14. Preliminary studies of a canine 13C-aminopyrine demethylation blood test.

    PubMed Central

    Moeller, E M; Steiner, J M; Williams, D A; Klein, P D

    2001-01-01

    The objectives of this study were to determine whether a 13C-aminopyrine demethylation blood test is technically feasible in clinically healthy dogs, whether oral administration of 13C-aminopyrine causes a detectable increase in percent dose/min (PCD) of 13C administered as 13C-aminopyrine and recovered in gas extracted from blood, and whether gas extraction efficiency has an impact on PCD. A dose of 2 mg/kg body weight of 13C-aminopyrine dissolved in deionized water was administered orally to 6 clinically healthy dogs. Blood samples were taken from each dog 0, 30, 60, and 120 min after administration of the 13C-aminopyrine. Carbon dioxide was extracted from blood samples by addition of acid and analyzed by fractional mass spectrometry. None of the 6 dogs showed any side effects after 13C-aminopyrine administration. All 6 dogs showed a measurable increase of the PCD in gas samples extracted from blood samples at 30 min, 60 min, and 120 min after 13C-aminopyrine administration. Coefficients of variation between the triplicate samples were statistically significantly higher for the %CO2, a measure of extraction efficiency, than for PCD values (P < 0.0001). The 13C-aminopyrine demethylation blood test described here is technically feasible. Oral administration of 13C-aminopyrine did not lead to gross side effects in the 6 dogs. Clinically healthy dogs show a measurable increase of PCD in gas extracted from blood samples after oral administration of 13C-aminopyrine. Efficiency of CO2 extraction from blood samples does not have an impact on PCD determined from these blood samples. This test may prove useful to evaluate hepatic function in dogs. PMID:11227194

  15. Economical synthesis of 13C-labeled opiates, cocaine derivatives and selected urinary metabolites by derivatization of the natural products.

    PubMed

    Karlsen, Morten; Liu, Huiling; Johansen, Jon Eigill; Hoff, Bård Helge

    2015-03-25

    The illegal use of opiates and cocaine is a challenge world-wide, but some derivatives are also valuable pharmaceuticals. Reference samples of the active ingredients and their metabolites are needed both for controlling administration in the clinic and to detect drugs of abuse. Especially, (13)C-labeled compounds are useful for identification and quantification purposes by mass spectroscopic techniques, potentially increasing accuracy by minimizing ion alteration/suppression effects. Thus, the synthesis of [acetyl-(13)C4]heroin, [acetyl-(13)C4-methyl-(13)C]heroin, [acetyl-(13)C2-methyl-(13)C]6-acetylmorphine, [N-methyl-(13)C-O-metyl-(13)C]codeine and phenyl-(13)C6-labeled derivatives of cocaine, benzoylecgonine, norcocaine and cocaethylene was undertaken to provide such reference materials. The synthetic work has focused on identifying (13)C atom-efficient routes towards these derivatives. Therefore, the (13)C-labeled opiates and cocaine derivatives were made from the corresponding natural products.

  16. Protonation of carbon single-walled nanotubes studied using 13C and 1H-13C cross polarization nuclear magnetic resonance and Raman spectroscopies.

    PubMed

    Engtrakul, Chaiwat; Davis, Mark F; Gennett, Thomas; Dillon, Anne C; Jones, Kim M; Heben, Michael J

    2005-12-14

    The reversible protonation of carbon single-walled nanotubes (SWNTs) in sulfuric acid and Nafion was investigated using solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies. Magic-angle spinning (MAS) was used to obtain high-resolution 13C and 1H-13C cross polarization (CP) NMR spectra. The 13C NMR chemical shifts are reported for bulk SWNTs, H2SO4-treated SWNTs, SWNT-Nafion polymer composites, SWNT-AQ55 polymer composites, and SWNTs in contact with water. Protonation occurs without irreversible oxidation of the nanotube substrate via a charge-transfer process. This is the first report of a chemically induced change in a SWNT 13C resonance brought about by a reversible interaction with an acidic proton, providing additional evidence that carbon nanotubes behave as weak bases. Cross polarization was found to be a powerful technique for providing an additional contrast mechanism for studying nanotubes in contact with other chemical species. The CP studies confirmed polarization transfer from nearby protons to nanotube carbon atoms. The CP technique was also applied to investigate water adsorbed on carbon nanotube surfaces. Finally, the degree of bundling of the SWNTs in Nafion films was probed with the 1H-13C CP-MAS technique.

  17. T(2) relaxation times of (13)C metabolites in a rat hepatocellular carcinoma model measured in vivo using (13)C-MRS of hyperpolarized [1-(13)C]pyruvate.

    PubMed

    Yen, Yi-Fen; Le Roux, Patrick; Mayer, Dirk; King, Randy; Spielman, Daniel; Tropp, James; Butts Pauly, Kim; Pfefferbaum, Adolf; Vasanawala, Shreyas; Hurd, Ralph

    2010-05-01

    A single-voxel Carr-Purcell-Meibloom-Gill sequence was developed to measure localized T(2) relaxation times of (13)C-labeled metabolites in vivo for the first time. Following hyperpolarized [1-(13)C]pyruvate injections, pyruvate and its metabolic products, alanine and lactate, were observed in the liver of five rats with hepatocellular carcinoma and five healthy control rats. The T(2) relaxation times of alanine and lactate were both significantly longer in HCC tumors than in normal livers (p < 0.002). The HCC tumors also showed significantly higher alanine signal relative to the total (13)C signal than normal livers (p < 0.006). The intra- and inter-subject variations of the alanine T(2) relaxation time were 11% and 13%, respectively. The intra- and inter-subject variations of the lactate T(2) relaxation time were 6% and 7%, respectively. The intra-subject variability of alanine to total carbon ratio was 16% and the inter-subject variability 28%. The intra-subject variability of lactate to total carbon ratio was 14% and the inter-subject variability 20%. The study results show that the signal level and relaxivity of [1-(13)C]alanine may be promising biomarkers for HCC tumors. Its diagnostic values in HCC staging and treatment monitoring are yet to be explored.

  18. Draft Genome Sequence of a Tropical Freshwater Cyanobacterium, Limnothrix sp. Strain P13C2

    PubMed Central

    Tan, Boon Fei; Gin, Karina Yew-Hoong

    2016-01-01

    A nonaxenic unialgal culture of Limnothrix sp. strain P13C2 was obtained through multiple subculturing of an inoculum obtained from a tropical freshwater lake. Here, we report the genome of P13C2 of 4.6 Mbp, extracted from the metagenome of this coculture. PMID:27795269

  19. 13C MRS studies of neuroenergetics and neurotransmitter cycling in humans.

    PubMed

    Rothman, Douglas L; De Feyter, Henk M; de Graaf, Robin A; Mason, Graeme F; Behar, Kevin L

    2011-10-01

    In the last 25 years, (13)C MRS has been established as the only noninvasive method for the measurement of glutamate neurotransmission and cell-specific neuroenergetics. Although technically and experimentally challenging, (13)C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, the energy cost of brain function, the high neuronal activity in the resting brain state and how neuroenergetics and neurotransmitter cycling are altered in neurological and psychiatric disease. In this article, the current state of (13)C MRS as it is applied to the study of neuroenergetics and neurotransmitter cycling in humans is reviewed. The focus is predominantly on recent findings in humans regarding metabolic pathways, applications to clinical research and the technical status of the method. Results from in vivo (13)C MRS studies in animals are discussed from the standpoint of the validation of MRS measurements of neuroenergetics and neurotransmitter cycling, and where they have helped to identify key questions to address in human research. Controversies concerning the relationship between neuroenergetics and neurotransmitter cycling and factors having an impact on the accurate determination of fluxes through mathematical modeling are addressed. We further touch upon different (13)C-labeled substrates used to study brain metabolism, before reviewing a number of human brain diseases investigated using (13)C MRS. Future technological developments are discussed that will help to overcome the limitations of (13)C MRS, with special attention given to recent developments in hyperpolarized (13)C MRS.

  20. Measuring δ(13)C values of atmospheric acetaldehyde via sodium bisulfite adsorption and cysteamine derivatisation.

    PubMed

    Guo, Songjun; Chen, Mei; Wen, Sheng; Sheng, Guoying; Fu, Jiamo

    2012-01-01

    δ(13)C values of gaseous acetaldehyde were measured by gas chromatograph-combustion-isotope ratio mass spectrometer (GC-C-IRMS) via sodium bisulfite (NaHSO(3)) adsorption and cysteamine derivatisation. Gaseous acetaldehyde was collected via NaHSO(3)-coated Sep-Pak(®) silica gel cartridge, then derivatised with cysteamine, and then the δ(13)C value of the acetaldehyde-cysteamine derivative was measured by GC-C-IRMS. Using two acetaldehydes with different δ(13)C values, derivatisation experiments were carried out to cover concentrations between 0.009×10(-3) and 1.96×10(-3) mg·l(-1)) of atmospheric acetaldehyde, and then δ(13)C fractionation was evaluated in the derivatisation of acetaldehyde based on stoichiometric mass balance after measuring the δ(13)C values of acetaldehyde, cysteamine and the acetaldehyde-cysteamine derivative. δ(13)C measurements in the derivertisation process showed good reproducibility (<0.5 ‰) for gaseous acetaldehyde. The differences between predicted and measured δ(13)C values were 0.04-0.31 ‰ for acetaldehyde-cysteamine derivative, indicating that the derivatisation introduces no isotope fractionation for gaseous acetaldehyde, and obtained δ(13)C values of acetaldehyde in ambient air at the two sites were distinct (-34.00 ‰ at an urban site versus-31.00 ‰ at a forest site), implying potential application of the method to study atmospheric acetaldehyde.

  1. Refined Analysis of Brain Energy Metabolism Using In Vivo Dynamic Enrichment of 13C Multiplets

    PubMed Central

    Dehghani M., Masoumeh; Duarte, João M. N.; Kunz, Nicolas; Gruetter, Rolf

    2016-01-01

    Carbon-13 nuclear magnetic resonance spectroscopy in combination with the infusion of 13C-labeled precursors is a unique approach to study in vivo brain energy metabolism. Incorporating the maximum information available from in vivo localized 13C spectra is of importance to get broader knowledge on cerebral metabolic pathways. Metabolic rates can be quantitatively determined from the rate of 13C incorporation into amino acid neurotransmitters such as glutamate and glutamine using suitable mathematical models. The time course of multiplets arising from 13C-13C coupling between adjacent carbon atoms was expected to provide additional information for metabolic modeling leading to potential improvements in the estimation of metabolic parameters. The aim of the present study was to extend two-compartment neuronal/glial modeling to include dynamics of 13C isotopomers available from fine structure multiplets in 13C spectra of glutamate and glutamine measured in vivo in rats brain at 14.1 T, termed bonded cumomer approach. Incorporating the labeling time courses of 13C multiplets of glutamate and glutamine resulted in elevated precision of the estimated fluxes in rat brain as well as reduced correlations between them. PMID:26969691

  2. Natural (13) C distribution in oil palm (Elaeis guineensis Jacq.) and consequences for allocation pattern.

    PubMed

    Lamade, Emmanuelle; Tcherkez, Guillaume; Darlan, Nuzul Hijri; Rodrigues, Rosario Lobato; Fresneau, Chantal; Mauve, Caroline; Lamothe-Sibold, Marlène; Sketriené, Diana; Ghashghaie, Jaleh

    2016-01-01

    Oil palm has now become one of the most important crops, palm oil representing nearly 25% of global plant oil consumption. Many studies have thus addressed oil palm ecophysiology and photosynthesis-based models of carbon allocation have been used. However, there is a lack of experimental data on carbon fixation and redistribution within palm trees, and important C-sinks have not been fully characterized yet. Here, we carried out extensive measurement of natural (13) C-abundance (δ(13) C) in oil palm tissues, including fruits at different maturation stages. We find a (13) C-enrichment in heterotrophic organs compared to mature leaves, with roots being the most (13) C-enriched. The δ(13) C in fruits decreased during maturation, reflecting the accumulation in (13) C-depleted lipids. We further used observed δ(13) C values to compute plausible carbon fluxes using a steady-state model of (13) C-distribution including metabolic isotope effects ((12) v/(13) v). The results suggest that fruits represent a major respiratory loss (≈39% of total tree respiration) and that sink organs such as fruits are fed by sucrose from leaves. That is, glucose appears to be a quantitatively important compound in palm tissues, but computations indicate that it is involved in dynamic starch metabolism rather that C-exchange between organs.

  3. Integrated 13C-metabolic flux analysis of 14 parallel labeling experiments in Escherichia coli.

    PubMed

    Crown, Scott B; Long, Christopher P; Antoniewicz, Maciek R

    2015-03-01

    The use of parallel labeling experiments for (13)C metabolic flux analysis ((13)C-MFA) has emerged in recent years as the new gold standard in fluxomics. The methodology has been termed COMPLETE-MFA, short for complementary parallel labeling experiments technique for metabolic flux analysis. In this contribution, we have tested the limits of COMPLETE-MFA by demonstrating integrated analysis of 14 parallel labeling experiments with Escherichia coli. An effort on such a massive scale has never been attempted before. In addition to several widely used isotopic tracers such as [1,2-(13)C]glucose and mixtures of [1-(13)C]glucose and [U-(13)C]glucose, four novel tracers were applied in this study: [2,3-(13)C]glucose, [4,5,6-(13)C]glucose, [2,3,4,5,6-(13)C]glucose and a mixture of [1-(13)C]glucose and [4,5,6-(13)C]glucose. This allowed us for the first time to compare the performance of a large number of isotopic tracers. Overall, there was no single best tracer for the entire E. coli metabolic network model. Tracers that produced well-resolved fluxes in the upper part of metabolism (glycolysis and pentose phosphate pathways) showed poor performance for fluxes in the lower part of metabolism (TCA cycle and anaplerotic reactions), and vice versa. The best tracer for upper metabolism was 80% [1-(13)C]glucose+20% [U-(13)C]glucose, while [4,5,6-(13)C]glucose and [5-(13)C]glucose both produced optimal flux resolution in the lower part of metabolism. COMPLETE-MFA improved both flux precision and flux observability, i.e. more independent fluxes were resolved with smaller confidence intervals, especially exchange fluxes. Overall, this study demonstrates that COMPLETE-MFA is a powerful approach for improving flux measurements and that this methodology should be considered in future studies that require very high flux resolution.

  4. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain

    NASA Astrophysics Data System (ADS)

    Tavernier, P.; Portais, J.-C.; Besson, I.; Courtois, J.; Courtois, B.; Barbotin, J.-N.

    1998-02-01

    Metabolic pathways implied in the synthesis of succinoglycan produced by the Su47 strain of R. meliloti were evaluated by 13C-NMR spectroscopy after incubation with [1{-}13C] or [2{-}13C] glucose. The biosynthesis of this polymer by R. meliloti from glucose occurred by a direct polymerisation of the introduced glucose and by the pentose phosphate pathway. Les voies métaboliques impliquées dans la synthèse du succinoglycane produit par la souche Su47 de R. meliloti ont été évaluées par la spectroscopie de RMN du carbone 13 après incubation des cellules avec du [1{-}13C] ou [2{-}13C] glucose. La biosynthèse de ce polymère à partir du glucose se produit par polymérisation directe du glucose et par la voie des pentoses phosphate.

  5. Fish Movement and Dietary History Derived from Otolith (delta)13C

    SciTech Connect

    Weber, P K; Finlay, J C; Power, M E; Phillis, C C; Ramon, C E; Eaton, G F; Ingram, B L

    2005-09-08

    Habitat use and food web linkages are critical data for fish conservation and habitat restoration efforts, particularly for threatened salmonids species. Otolith microchemistry has been shown to be a powerful tool for reconstructing fish movement, but over small distances (kilometers), geology-derived differences in otolith chemistry are rare. Here, we demonstrate that otolith {sup 13}C/{sup 12}C ratio (i.e. {delta}{sup 13}C) of anadromous steelhead trout can be used to distinguish residence in small streams from residence in larger streams and rivers. While previous research has shown that water dissolved inorganic carbon {delta}{sup 13}C is the primary source of carbon in otoliths, the downstream change in food {delta}{sup 13}C in this watershed appears to be the primary control on otolith {delta}{sup 13}C. As a result, this method can also be applied to the problem of reconstructing feeding history at a location.

  6. Reconstruction of δ 13C of chemocline CO 2 (aq) in past oceans and lakes using the δ 13C of fossil isorenieratene

    NASA Astrophysics Data System (ADS)

    van Breugel, Yvonne; Schouten, Stefan; Paetzel, Matthias; Ossebaar, Jort; Sinninghe Damsté, Jaap S.

    2005-06-01

    High abundances of the diaromatic carotenoid isorenieratene derived from photosynthetic green sulfur bacteria (Chlorobiaceae) were found just below the chemocline in an anoxic fjord in Norway, throughout the annual cycle. The stable carbon isotope composition of this carotenoid co-varied with the δ 13C of CO 2 (aq) and is independent of the CO 2 and isorenieratene concentration. This constant isotopic fractionation ɛp of isorenieratene versus CO 2, 4 ± 1‰, was subsequently used in the reconstruction of δ 13C of CO 2 at the chemocline in ancient oceans and lakes. These reconstructions indicate that δ 13C of CO 2 at the chemocline is often influenced by isotopically light CO 2, formed by remineralization of organic matter. This process can, depending on the depth and stability of the chemocline, also effect the isotopic composition of the phytoplankton and, thus, isotopic records of sedimentary inorganic and organic carbon.

  7. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    PubMed Central

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ,ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1–40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1–40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16–21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1–40 fibrils in 4 hr or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples. PMID:23562665

  8. An overview of methods using (13)C for improved compound identification in metabolomics and natural products.

    PubMed

    Clendinen, Chaevien S; Stupp, Gregory S; Ajredini, Ramadan; Lee-McMullen, Brittany; Beecher, Chris; Edison, Arthur S

    2015-01-01

    Compound identification is a major bottleneck in metabolomics studies. In nuclear magnetic resonance (NMR) investigations, resonance overlap often hinders unambiguous database matching or de novo compound identification. In liquid chromatography-mass spectrometry (LC-MS), discriminating between biological signals and background artifacts and reliable determination of molecular formulae are not always straightforward. We have designed and implemented several NMR and LC-MS approaches that utilize (13)C, either enriched or at natural abundance, in metabolomics applications. For LC-MS applications, we describe a technique called isotopic ratio outlier analysis (IROA), which utilizes samples that are isotopically labeled with 5% (test) and 95% (control) (13)C. This labeling strategy leads to characteristic isotopic patterns that allow the differentiation of biological signals from artifacts and yield the exact number of carbons, significantly reducing possible molecular formulae. The relative abundance between the test and control samples for every IROA feature can be determined simply by integrating the peaks that arise from the 5 and 95% channels. For NMR applications, we describe two (13)C-based approaches. For samples at natural abundance, we have developed a workflow to obtain (13)C-(13)C and (13)C-(1)H statistical correlations using 1D (13)C and (1)H NMR spectra. For samples that can be isotopically labeled, we describe another NMR approach to obtain direct (13)C-(13)C spectroscopic correlations. These methods both provide extensive information about the carbon framework of compounds in the mixture for either database matching or de novo compound identification. We also discuss strategies in which (13)C NMR can be used to identify unknown compounds from IROA experiments. By combining technologies with the same samples, we can identify important biomarkers and corresponding metabolites of interest.

  9. 13C magnetic resonance spectroscopy measurements with hyperpolarized [1‐13C] pyruvate can be used to detect the expression of transgenic pyruvate decarboxylase activity in vivo

    PubMed Central

    Dzien, Piotr; Tee, Sui‐Seng; Kettunen, Mikko I.; Lyons, Scott K.; Larkin, Timothy J.; Timm, Kerstin N.; Hu, De‐En; Wright, Alan; Rodrigues, Tiago B.; Serrao, Eva M.; Marco‐Rius, Irene; Mannion, Elizabeth; D'Santos, Paula; Kennedy, Brett W. C.

    2015-01-01

    Purpose Dissolution dynamic nuclear polarization can increase the sensitivity of the 13C magnetic resonance spectroscopy experiment by at least four orders of magnitude and offers a novel approach to the development of MRI gene reporters based on enzymes that metabolize 13C‐labeled tracers. We describe here a gene reporter based on the enzyme pyruvate decarboxylase (EC 4.1.1.1), which catalyzes the decarboxylation of pyruvate to produce acetaldehyde and carbon dioxide. Methods Pyruvate decarboxylase from Zymomonas mobilis (zmPDC) and a mutant that lacked enzyme activity were expressed using an inducible promoter in human embryonic kidney (HEK293T) cells. Enzyme activity was measured in the cells and in xenografts derived from the cells using 13C MRS measurements of the conversion of hyperpolarized [1‐13C] pyruvate to H13 CO3–. Results Induction of zmPDC expression in the cells and in the xenografts derived from them resulted in an approximately two‐fold increase in the H13 CO3–/[1‐13C] pyruvate signal ratio following intravenous injection of hyperpolarized [1‐13C] pyruvate. Conclusion We have demonstrated the feasibility of using zmPDC as an in vivo reporter gene for use with hyperpolarized 13C MRS. Magn Reson Med 76:391–401, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26388418

  10. Temperature and density evolution during decay in a 2.45 GHz hydrogen electron cyclotron resonance plasma: Off-resonant and resonant cases

    SciTech Connect

    Cortázar, O. D.

    2013-09-15

    Time resolved electron temperature and density measurements during the decay stage in a hydrogen electron cyclotron resonance (ECR) plasma are presented for a resonance and off-resonance magnetic field configurations. The measurements are conducted on a ECR plasma generator excited at 2.45 GHz denominated test-bench for ion-sources plasma studies at ESS Bilbao. The plasma parameters evolution is studied by Langmuir probe diagnostic with synchronized sample technique developed for repetitive pulsed plasmas with a temporal resolution of 200 ns in typical decay processes of about 40 μs. An afterglow transient is clearly observed in the reflected microwave power signal from the plasma. Simultaneously, the electron temperature evolution shows rebounding peaks that may be related to the interplay between density drop and microwave coupling with deep impact on the Electron Energy Distribution Function. The correlation of such structures with the plasma absorbed power and the coupling quality is also reported.

  11. Light-shift suppression in a miniaturized Mx optically pumped Cs magnetometer array with enhanced resonance signal using off-resonant laser pumping.

    PubMed

    Scholtes, Theo; Schultze, Volkmar; IJsselsteijn, Rob; Woetzel, Stefan; Meyer, Hans-Georg

    2012-12-31

    The performance of an optically pumped Mx magnetometer with miniaturized Cs cell at earth's magnetic field strength (50 μT) is investigated. Operation using detuned high intensity laser light is shown to be superior to the conventional resonant operation in terms of the projected shot-noise-limited ( 50 fT/√Hz) and the actual noise-limited sensitivity using a noise compensation method. The Zeeman light shift effect, emerging due to the off-resonant circularly polarized laser radiation and leading to a strong orientational dependence of the measurement, is suppressed by averaging two identical magnetometer configurations pumped with oppositely circularly polarized light. A residual heading error within the range of 14 nT, limited by the present experimental characterization setup, was achieved.

  12. Weak value amplification of an off-resonance Goos-Hänchen shift in a Kretschmann-Raether surface plasmon resonance device.

    PubMed

    Parks, A D; Spence, S E

    2015-06-20

    During the past two decades there has been increased interest in the optical excitation of surface plasmon resonance (SPR) at a metal-dielectric interface. This is due in large part to its potential applications in such areas as medical diagnostics and pharmaceutical research. Also occurring during this time has been a growing recognition by the quantum physics community that weak value amplification (WVA) can serve as a valuable metrological research resource. Recently WVA has been used to amplify very small optical Goos-Hänchen (GH) shifts in glass and it has also been shown that SPR can greatly enhance optical GH shifts at the metal/air interface in Kretschmann-Raether (KR) devices. This paper demonstrates experimentally the WVA of an off-resonance GH shift in a KR device and explains why WVA of sufficiently SPR enhanced optical GH shifts cannot be achieved.

  13. Foliar d13C within a temperate deciduous forest: spatial, temporal, and species sources of variation

    SciTech Connect

    Garten Jr, Charles T; TaylorJr, G. E.

    1992-04-01

    Foliar {sup 13}C-abundance ({delta}{sup 13}C) was analyzed in the dominant trees of a temperate deciduous forest in east Tennessee (Walker Branch Watershed) to investigate the variation in foliar {delta}{sup 13}C as a function of time (within-year and between years), space (canopy height, watershed topography and habitat) and species (deciduous and coniferous taxa). Various hypotheses were tested by analyzing (i) samples collected from the field during the growing season and (ii) foliar tissues maintained in an archived collection. The {delta}{sup 13}C-value for leaves from the tops of trees was 2 to 3%. more positive than for leaves sampled at lower heights in the canopy. Quercus prinus leaves sampled just prior to autumn leaf fall had significantly more negative {delta}{sup 13}C-values than those sampled during midsummer. On the more xeric ridges, needles of Pinus spp. had more positive {delta}{sup 13}C-values than leaves from deciduous species. Foliar {delta}{sup 13}C-values differed significantly as a function of topography. Deciduous leaves from xeric sites (ridges and slopes) had more positive {delta}{sup 13}C-values than those from mesic (riparian and cove) environments. On the more xeric sites, foliar {delta}{sup 13}C was significantly more positive in 1988 (a dry year) relative to that in 1989 (a year with above-normal precipitation). In contrast, leaf {delta}{sup 13}C in trees from mesic valley bottoms did not differ significantly among years with disparate precipitation. Patterns in foliar {delta}{sup 13}C indicated a higher ratio of net CO{sub 2} assimilation to transpiration (A/E) for trees in more xeric versus mesic habitats, and for trees in xeric habitats during years of drought versus years of normal precipitation. However, A/E (units of mmol CO{sub 2} fixed/mol H{sub 2}O transpired) calculated on the basis of {delta}{sup 13}C-values for leaves from the more xeric sites was higher in a wet year (6.6 {+-} 1.2) versus a dry year (3.4 {+-} 0.4). This

  14. Advanced new relaxation filter-selective signal excitation methods for (13)C solid-state nuclear magnetic resonance.

    PubMed

    Asada, Mamiko; Nemoto, Takayuki; Mimura, Hisashi; Sako, Kazuhiro

    2014-10-21

    We have developed new relaxation filter-selective signal excitation (RFS) methods for (13)C solid-state NMR, which enable extraction of the spectrum of a target component from a mixture of several components. These methods are based on the equalization of proton relaxation time in a single domain via rapid intraproton spin diffusion and the difference in proton relaxation time of individual components in the mixture. We recently reported two types of RFS methods using proton spin-lattice relaxation time in the rotating frame ((1)H T1rho) in (13)C solid-state nuclear magnetic resonance (NMR) spectroscopy. Here, to increase the availability of RFS methods, we focus on proton spin-lattice relaxation time ((1)H T1). Introduction of simple pulse sequences to one-dimensional experiments reduced data acquisition time and increased flexibility, and led to the development of two new types of RFS methods using (1)H T1. We then demonstrated these methods by selectively exciting the (13)C signals of target components in a commercially available drug and a number of physical mixtures, and we showed them to be applicable to the quantitative analysis of individual components in these solid mixtures with an experimental duration of 1.5 to about 10 h. The practicality and versatility of these four RFS methods were increased by combining two or more of them, or by using a flip-back pulse, which is an effective means of shortening experimental duration. These RFS methods are suitable for use in a broad range of fields.

  15. Precise Observations of the 12C/13C Ratios of HC3N in the Low-mass Star-forming Region L1527

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    Using the Green Bank 100 m telescope and the Nobeyama 45 m telescope, we have observed the rotational emission lines of the three 13C isotopic species of HC3N in the 3 and 7 mm bands toward the low-mass star-forming region L1527 in order to explore their anomalous 12C/13C ratios. The column densities of the 13C isotopic species are derived from the intensities of the J = 5-4 lines observed at high signal-to-noise ratios. The abundance ratios are determined to be 1.00:1.01 ± 0.02:1.35 ± 0.03:86.4 ± 1.6 for [H13CCCN]:[HC13CCN]:[HCC13CN]:[HCCCN], where the errors represent one standard deviation. The ratios are very similar to those reported for the starless cloud Taurus Molecular Cloud-1 Cyanopolyyne Peak (TMC-1 CP). These ratios cannot be explained by thermal equilibrium, but likely reflect the production pathways of this molecule. We have shown the equality of the abundances of H13CCCN and HC13CCN at a high-confidence level, which supports the production pathways of HC3N via C2H2 and {{{C}}}2{{{{H}}}2}+. The average 12C/13C ratio for HC3N is 77 ± 4, which may be only slightly higher than the elemental 12C/13C ratio. Dilution of the 13C isotope in HC3N is not as significant as that in CCH or c-C3H2. We have also simultaneously observed the DCCCN and HCCC15N lines and derived the isotope ratios [DCCCN]/[HCCCN] = 0.0370 ± 0.0007 and [HCCCN]/[HCCC15N] = 338 ± 12.

  16. Simultaneous imaging of 13C metabolism and 1H structure: technical considerations and potential applications.

    PubMed

    Gordon, Jeremy W; Fain, Sean B; Niles, David J; Ludwig, Kai D; Johnson, Kevin M; Peterson, Eric T

    2015-05-01

    Real-time imaging of (13)C metabolism in vivo has been enabled by recent advances in hyperpolarization. As a result of the inherently low natural abundance of endogenous (13)C nuclei, hyperpolarized (13)C images lack structural information that could be used to aid in motion detection and anatomical registration. Motion before or during the (13)C acquisition can therefore result in artifacts and misregistration that may obscure measures of metabolism. In this work, we demonstrate a method to simultaneously image both (1)H and (13)C nuclei using a dual-nucleus spectral-spatial radiofrequency excitation and a fully coincident readout for rapid multinuclear spectroscopic imaging. With the appropriate multinuclear hardware, and the means to simultaneously excite and receive on both channels, this technique is straightforward to implement requiring little to no increase in scan time. Phantom and in vivo experiments were performed with both Cartesian and spiral trajectories to validate and illustrate the utility of simultaneous acquisitions. Motion compensation of dynamic metabolic measurements acquired during free breathing was demonstrated using motion tracking derived from (1)H data. Simultaneous multinuclear imaging provides structural (1)H and metabolic (13)C images that are correlated both spatially and temporally, and are therefore amenable to joint (1)H and (13)C analysis and correction of structure-function images.

  17. Are accurate computations of the 13C' shielding feasible at the DFT level of theory?

    PubMed

    Vila, Jorge A; Arnautova, Yelena A; Martin, Osvaldo A; Scheraga, Harold A

    2014-02-05

    The goal of this study is twofold. First, to investigate the relative influence of the main structural factors affecting the computation of the (13)C' shielding, namely, the conformation of the residue itself and the next nearest-neighbor effects. Second, to determine whether calculation of the (13)C' shielding at the density functional level of theory (DFT), with an accuracy similar to that of the (13)C(α) shielding, is feasible with the existing computational resources. The DFT calculations, carried out for a large number of possible conformations of the tripeptide Ac-GXY-NMe, with different combinations of X and Y residues, enable us to conclude that the accurate computation of the (13)C' shielding for a given residue X depends on the: (i) (ϕ,ψ) backbone torsional angles of X; (ii) side-chain conformation of X; (iii) (ϕ,ψ) torsional angles of Y; and (iv) identity of residue Y. Consequently, DFT-based quantum mechanical calculations of the (13)C' shielding, with all these factors taken into account, are two orders of magnitude more CPU demanding than the computation, with similar accuracy, of the (13)C(α) shielding. Despite not considering the effect of the possible hydrogen bond interaction of the carbonyl oxygen, this work contributes to our general understanding of the main structural factors affecting the accurate computation of the (13)C' shielding in proteins and may spur significant progress in effort to develop new validation methods for protein structures.

  18. [Determination of 13C enrichment in soil amino acid enantiomers by gas chromatogram/mass spectrometry].

    PubMed

    He, Hong-Bo; Zhang, Wei; Ding, Xue-Li; Bai, Zhen; Liu, Ning; Zhang, Xu-Dong

    2008-06-01

    The transformation and renewal of amino acid enantiomers is of significance in indicating the turnover mechanism of soil organic matter. In this paper, a method of gas chromatogram/mass spectrometry combined with U-13 C-glucose incubation was developed to determine the 13C enrichment in soil amino acid enantiomers, which could effectively differentiate the original and the newly synthesized amino acids in soil matrix. The added U-13 C-glucose was utilized rapidly to structure the amino acid carbon skeleton, and the change of relative abundance of isotope ions could be determined by mass spectrometry. The direct incorporation of U-13 C glucose was estimated by the intensity increase of m/z (F + n) to F (F was parent fragment, and n was the carbon number in the fragment), while the total isotope incorporation from the added 13C could be calculated according to the abundance ratio increment summation from m/z (Fa + 1) through (Fa + T) (Fa was the fragment containing all original skeleton carbons, and T was the carbon number in the amino acid molecule). The 13C enrichment in the target compound was expressed as atom percentage excess (APE), and that of D-amino acid needed to be corrected by the coefficient of hydrolysis-induced racemization. The 13C enrichment reflected the carbon turnover velocity of individual amino acid enantiomers, and was powerful to investigate the dynamics of soil amino acids.

  19. Deposition of 13C tracer in the JET MkII-HD divertor

    NASA Astrophysics Data System (ADS)

    Likonen, J.; Airila, M.; Alves, E.; Barradas, N.; Brezinsek, S.; Coad, J. P.; Devaux, S.; Groth, M.; Grünhagen, S.; Hakola, A.; Jachmich, S.; Koivuranta, S.; Makkonen, T.; Rubel, M.; Strachan, J.; Stamp, M.; Widdowson, A.; EFDA contributors, JET-

    2011-12-01

    Migration of 13C has been investigated at JET by injecting 13C-labelled methane at the outer divertor base at the end of the 2009 campaign. The 13C deposition profiles on carbon fibre composite divertor tiles were measured by secondary ion mass spectrometry and Rutherford backscattering techniques. 13C was mainly deposited near the puffing location on the outer divertor base tiles. High amounts of 13C were also found at the outer vertical target: at the bottom of the lower and at the top of the upper plates. Thirty-three percent of puffed 13CH4 was instantly pumped out by the divertor cryopump, which is close to the pump duct entrance. Global 13C transport in the torus was modelled by the EDGE2D/EIRENE and DIVIMP codes, and local 13C migration in the vicinity of the injection location by the ERO code. The DIVIMP and EDGE2D simulations show strong prompt deposition of 13C directly adjacent to the injection point as well as in the far scrape-off layer (SOL) along both the inner and outer divertor targets. In addition, the measured 13C deposition along the outer divertor wall tiles is qualitatively reproduced. However, EDGE2D and DIVIMP do not predict any deposition along the divertor surfaces facing the private plasma on the inner floor tile and inboard of the outer strike point on tile 5. The ERO calculations also indicate that most of the deposition occurs close to the injection location on the vertical face of the LBSRP tile and the horizontal part of tile 6.

  20. Clinical NOE 13C MRS for neuropsychiatric disorders of the frontal lobe

    NASA Astrophysics Data System (ADS)

    Sailasuta, Napapon; Robertson, Larry W.; Harris, Kent C.; Gropman, Andrea L.; Allen, Peter S.; Ross, Brian D.

    2008-12-01

    In this communication, a scheme is described whereby in vivo 13C MRS can safely be performed in the frontal lobe, a human brain region hitherto precluded on grounds of SAR, but important in being the seat of impaired cognitive function in many neuropsychiatric and developmental disorders. By combining two well known features of 13C NMR—the use of low power NOE and the focus on 13C carbon atoms which are only minimally coupled to protons, we are able to overcome the obstacle of SAR and develop means of monitoring the 13C fluxes of critically important metabolic pathways in frontal brain structures of normal volunteers and patients. Using a combination of low-power WALTZ decoupling, variants of random noise for nuclear overhauser effect enhancement it was possible to reduce power deposition to 20% of the advised maximum specific absorption rate (SAR). In model solutions 13C signal enhancement achieved with this scheme were comparable to that obtained with WALTZ-4. In human brain, the low power procedure effectively determined glutamine, glutamate and bicarbonate in the posterior parietal brain after [1- 13C] glucose infusion. The same 13C enriched metabolites were defined in frontal brain of human volunteers after administration of [1- 13C] acetate, a recognized probe of glial metabolism. Time courses of incorporation of 13C into cerebral glutamate, glutamine and bicarbonate were constructed. The results suggest efficacy for measurement of in vivo cerebral metabolic rates of the glutamate-glutamine and tricarboxylic acid cycles in 20 min MR scans in previously inaccessible brain regions in humans at 1.5T. We predict these will be clinically useful biomarkers in many human neuropsychiatric and genetic conditions.

  1. Quantitative 13C traces of glucose fate in hepatitis B virus infected hepatocytes.

    PubMed

    Wan, Qianfen; Wang, Yulan; Tang, Huiru

    2017-02-21

    Quantitative characterization of 13C-labeled metabolites is an important part of the stable isotope tracing method widely used in metabolic flux analysis. Due to long relaxation time and low sensitivity of 13C nuclei, direct measurement of 13C labeled metabolites using one dimensional 13C NMR often fails to meet the demand of metabolomics studies especially with large number of samples and metabolites having low abundance. Although HSQC-based 2D NMR methods have improved sensitivity with inversion detection, they are time-consuming thus unsuitable for high-throughput absolute quantification of 13C-labeled metabolites. In this study, we developed a method for absolute quantification of 13C labeled metabolites using naturally abundant TSP as a reference with the first increment of HMQC pulse sequence, taking polarization transfer efficiencies into consideration. We validated this method using a mixture of 13C-labeled alanine, methionine, glucose and formic acid together with a mixture of alanine, lactate, glycine, uridine, cytosine, and hypoxanthine having natural 13C abundance with known concentrations. We subsequently applied this method to analyze the flux of glucose in HepG2 cells infected with hepatitis B virus (HBV). The results showed that HBV infection increased the cellular uptake of glucose, stimulated glycolysis and enhanced the pentose phosphate and hexosamine pathways for biosynthesis of RNA and DNA and nucleotide sugars to facilitate HBV replication. This method saves experimental time and provides a possibility for absolute quantitative tracking of the 13C labeled metabolites for high throughput studies.

  2. Detecting response of rat C6 glioma tumors to radiotherapy using hyperpolarized [1- 13C]pyruvate and 13C magnetic resonance spectroscopic imaging.

    PubMed

    Day, Sam E; Kettunen, Mikko I; Cherukuri, Murali Krishna; Mitchell, James B; Lizak, Martin J; Morris, H Douglas; Matsumoto, Shingo; Koretsky, Alan P; Brindle, Kevin M

    2011-02-01

    We show here that hyperpolarized [1-(13) C]pyruvate can be used to detect treatment response in a glioma tumor model; a tumor type where detection of response with (18) fluoro-2-deoxyglucose, using positron emission tomography, is limited by the high background signals from normal brain tissue. (13) C chemical shift images acquired following intravenous injection of hyperpolarized [1-(13) C]pyruvate into rats with implanted C6 gliomas showed significant labeling of lactate within the tumors but comparatively low levels in surrounding brain.Labeled pyruvate was observed at high levels in blood vessels above the brain and from other major vessels elsewhere but was detected at only low levels in tumor and brain.The ratio of hyperpolarized (13) C label in tumor lactate compared to the maximum pyruvate signal in the blood vessels was decreased from 0.38 ± 0.16 to 0.23 ± 0.13, (a reduction of 34%) by 72 h following whole brain irradiation with 15 Gy.

  3. Determination of the Orientation and Dynamics of Ergosterol in Model Membranes Using Uniform 13C Labeling and Dynamically Averaged 13C Chemical Shift Anisotropies as Experimental Restraints

    PubMed Central

    Soubias, O.; Jolibois, F.; Massou, S.; Milon, A.; Réat, V.

    2005-01-01

    A new strategy was established to determine the average orientation and dynamics of ergosterol in dimyristoylphosphatidylcholine model membranes. It is based on the analysis of chemical shift anisotropies (CSAs) averaged by the molecular dynamics. Static 13C CSA tensors were computed by quantum chemistry, using the gauge-including atomic-orbital approach within Hartree-Fock theory. Uniformly 13C-labeled ergosterol was purified from Pichia pastoris cells grown on labeled methanol. After reconstitution into dimyristoylphosphatidylcholine lipids, the complete 1H and 13C assignment of ergosterol's resonances was performed using a combination of magic-angle spinning two-dimensional experiments. Dynamically averaged CSAs were determined by standard side-band intensity analysis for isolated 13C resonances (C3 and ethylenic carbons) and by off-magic-angle spinning experiments for other carbons. A set of 18 constraints was thus obtained, from which the sterol's molecular order parameter and average orientation could be precisely defined. The validity of using computed CSAs in this strategy was verified on cholesterol model systems. This new method allowed us to quantify ergosterol's dynamics at three molar ratios: 16 mol % (Ld phase), 30 mol % (Lo phase), and 23 mol % (mixed phases). Contrary to cholesterol, ergosterol's molecular diffusion axis makes an important angle (14°) with the inertial axis of the rigid four-ring system. PMID:15923221

  4. Synthesis of D-[U-{sup 13}C]Glucal, D-[U-{sup 13}C] Galactal, and L-[U-{sup 13}C]Fucose for NMR structure studies of oligosaccharides

    SciTech Connect

    Wu, R.; Unkefer, C.J.; Silks, L.A. III

    1996-12-31

    The role of carbohydrates is well recognized in a variety of important biological phenomena such as cell surface recognition. Recent advances in carbohydrate chemistry, including the development of solid phase synthesis methods, have helped to provide significant quantities of material by offering general protocols for synthesis of well-defined, pure material. However, the study of the solution structure of oligosaccharides by nuclear magnetic resonance techniques have been hampered by the lack of enriched {sup 13}C material. In an effort to help alleviate this situation, we have been interested in the construction of the title compounds from a single economical carbon source, D-[U-{sup 13}C]glucose. Details of the syntheses will be provided.

  5. VizieR Online Data Catalog: The mm and sub-mm spectra of 13C-glycolaldehydes (Haykal+, 2013)

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Motiyenko, R. A.; Margules, L.; Huet, T. R.

    2012-11-01

    To allow the detection of the 13C-isotopologues of glycolaldeh the interstellar medium, their rotational spectra in the millimeter and submillimeter-wave regions were studied. The spectra of 13CH2OHCHO and CH2OH13CHO were recorded in the 150-945GHz spectral range in the laboratory using a solid-state submillimeter-wave spectrometer in Lille. The observed line frequencies were measured with accuracy, better than 30kHz up to 700GHz and 50kHz above. The analysis was performed using a standard Watson Hamiltonian. Around 10000 new lines were identified for each isotopologue. The spectroscopic parameters were determined for the ground and the three lowest vibrational states, respectively up to 945 and 630GHz. Previous microwave assignments of 13CH2OHCHO were not confirmed. The provided line-lists and sets of molecular parameters meet the needs for a first astrophysical search of 13C-glycolaldehydes. (2 data files).

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

    DOEpatents

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

    2008-01-22

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

  7. Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil

    USGS Publications Warehouse

    Qi, Haiping; Coplen, Tyler B.; Geilmann, Heike; Brand, Willi A.; Böhlke, John Karl

    2003-01-01

    Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a δ13C value of −26.24‰ relative to VPDB and a δ15N value of −4.52‰ relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a δ13C value of +37.76‰ and a δ15N value of +47.57‰. The δ13C and δ15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (δ13C = +1.95‰), L-SVEC lithium carbonate (δ13C = −46.48‰), IAEA-N-1 ammonium sulfate (δ15N = 0.43‰), and USGS32 potassium nitrate (δ15N = 180‰) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of δ13C is better than 0.13‰, and that of δ15N is better than 0.13‰ in 100-μg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a δ13C value for NBS 22 oil of −29.91‰, in contrast to the commonly accepted value of −29.78‰ for which off-line blank corrections probably have not been quantified satisfactorily.

  8. Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil

    USGS Publications Warehouse

    Qi, Haiping; Coplen, Tyler B.; Geilmann, Heike; Brand, Willi A.; Böhlke, J.K.

    2003-01-01

    Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a δ13C value of −26.24‰ relative to VPDB and a δ15N value of −4.52‰ relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a δ13C value of +37.76‰ and a δ15N value of +47.57‰. The δ13C and δ15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (δ13C = +1.95‰), L-SVEC lithium carbonate (δ13C = −46.48‰), IAEA-N-1 ammonium sulfate (δ15N = 0.43‰), and USGS32 potassium nitrate (δ15N = 180‰) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of δ13C is better than 0.13‰, and that of δ15N is better than 0.13‰ in 100-μg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a δ13C value for NBS 22 oil of −29.91‰, in contrast to the commonly accepted value of −29.78‰ for which off-line blank corrections probably have not been quantified satisfactorily.

  9. Derivatives of pyrazinecarboxylic acid: 1H, 13C and 15N NMR spectroscopic investigations.

    PubMed

    Holzer, Wolfgang; Eller, Gernot A; Datterl, Barbara; Habicht, Daniela

    2009-07-01

    NMR spectroscopic studies are undertaken with derivatives of 2-pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts ((1)H, (13)C, (15)N) and coupling constants ((1)H,(1)H; (13)C,(1)H; (15)N,(1)H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of (13)C,(1)H spin coupling constants is accomplished by 2D (delta,J) long-range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3-hydroxy-2-pyrazinecarboxylic acid are discussed.

  10. Isotopic ((13)C) fractionation during plant residue decomposition and its implications for soil organic matter studies.

    PubMed

    Schweizer; Fear; Cadisch

    1999-07-01

    Carbon isotopic fractionations in plant materials and those occurring during decomposition have direct implications in studies of short-and longer-term soil organic matter dynamics. Thus the products of decomposition, the evolved CO(2) and the newly formed soil organic matter, may vary in their (13)C signature from that of the original plant material. To evaluate the importance of such fractionation processes, the variations in (13)C signatures between and within plant parts of a tropical grass (Brachiaria humidicola) and tropical legume (Desmodium ovalifolium) were measured and the changes in (13)C content (signatures) during decomposition were monitored over a period of four months. As expected the grass materials were less depleted in (13)C (-11.4 to -11.9 per thousand) than those of the legume (-27.3 to -25.8 per thousand). Root materials of the legume were less (1.5 per thousand) depleted in (13)C compared with the leaves. Plant lignin-C was strongly depleted in (13)C compared with the bulk material by up to 2.5 per thousand in the legume and up to 4.7 per thousand in the grass. Plant materials were subsequently incubated in a sand/nutrient-solution/microbial inoculum mixture. The respiration product CO(2) was trapped in NaOH and precipitated as CaCO(3), suitable for analysis using an automated C/N analyser coupled to an isotope ratio mass spectrometer. Significant depletion in (13)C of the evolved CO(2) was observed during the initial stages of decomposition probably as a result of microbial fractionation as it was not associated with the (13)C signatures of the measured more decomposable fractions (non-acid detergent fibre and cellulose). While the cumulative CO(2)-(13)C signatures of legume materials became slightly enriched with ongoing decomposition, the CO(2)-C of the grass materials remained depleted in (13)C. Associated isotopic fractionation correction factors for source identification of CO(2-)C varied with time and suggested errors of 2-19% in the

  11. Isotopomer studies of gluconeogenesis and the Krebs cycle with 13C-labeled lactate.

    PubMed

    Katz, J; Wals, P; Lee, W N

    1993-12-05

    Fasted rats were intragastrically infused with either [2,3-13C]lactate or [1,2,3-13C]lactate. The infusate also contained 14C-labeled lactate and [3-3H]glucose. Glucose, alanine, glutamate, and glutamine were isolated from liver and blood. There was near complete equilibration of lactate and alanine, and the relative specific activities and relative enrichments were the same in blood and liver. Glucose was cleaved enzymatically to lactate. The compounds were examined by gas chromatography-mass spectroscopy. From the mass isotopomer spectra of the lactate, glutamate, and glutamine and their cleavage fragments the positional isotopomer composition of these compounds was obtained. The enrichment and isotopomer pattern in the lactate from cleaved glucose represents that in phosphoenolpyruvate (PEP). When [1,2,3-13C]lactate was infused the mass isotopomer spectrum of glutamates consisted only of compounds containing either one, two, or three 13C carbons per molecule (m1, m2, and m3). There was little 13C in C-4 and C-5 of glutamate. The rate of pyruvate decarboxylation is low, and 3-4% of the acetyl-CoA flux in the Krebs cycle is contributed by lactate carbon. The major isotopomers in lactate, alanine, and PEP were m3 and m2 with 13C in C-2 and C-3. The predominant isotopomer in PEP from [2,3-13C]lactate was m2 with 13C in C-2 and C-3. There was much more of m1 isotopomer with 13C in C-3 and C-2 than the m1 isotopomer with 13C in C-1. There was very little m3, the isotopomer with 13C in all three carbons. Most of the 13C in C-3 and C-4 of glucose and C-1 of glutamate was introduced via 13CO2 fixation. From the isotopomer distribution and the rate of glucose turnover we deduced, applying the analysis described in the "Appendix," the absolute rates of gluconeogenic pathways, recycling of PEP and the Cori cycle, and flux in the Krebs cycle. The flux from oxaloacetate (OAA)-->PEP was seven times that of OAA-->citrate, and about half of PEP was recycled to pyruvate via

  12. A roadmap for interpreting 13C metabolite labeling patterns from cells

    PubMed Central

    Buescher, Joerg M.; Antoniewicz, Maciek R.; Boros, Laszlo G.; Burgess, Shawn C.; Brunengraber, Henri; Clish, Clary B.; DeBerardinis, Ralph J.; Feron, Olivier; Frezza, Christian; Ghesquiere, Bart; Gottlieb, Eyal; Hiller, Karsten; Jones, Russell G.; Kamphorst, Jurre J.; Kibbey, Richard G.; Kimmelman, Alec C.; Locasale, Jason W.; Lunt, Sophia Y.; Maddocks, Oliver D. K.; Malloy, Craig; Metallo, Christian M.; Meuillet, Emmanuelle J.; Munger, Joshua; Nöh, Katharina; Rabinowitz, Joshua D.; Ralser, Markus; Sauer, Uwe; Stephanopoulos, Gregory; St-Pierre, Julie; Tennant, Daniel A.; Wittmann, Christoph; Vander Heiden, Matthew G.; Vazquez, Alexei; Vousden, Karen; Young, Jamey D.; Zamboni, Nicola; Fendt, Sarah-Maria

    2015-01-01

    Measuring intracellular metabolism has increasingly led to important insights in biomedical research. 13C tracer analysis, although less information-rich than quantitative 13C flux analysis that requires computational data integration, has been established as a time-efficient method to unravel relative pathway activities, qualitative changes in pathway contributions, and nutrient contributions. Here, we review selected key issues in interpreting 13C metabolite labeling patterns, with the goal of drawing accurate conclusions from steady state and dynamic stable isotopic tracer experiments. PMID:25731751

  13. Assessing Oxidative Stress in Tumors by Measuring the Rate of Hyperpolarized [1-13C]Dehydroascorbic Acid Reduction Using 13C Magnetic Resonance Spectroscopy*

    PubMed Central

    Timm, Kerstin N.; Hu, De-En; Williams, Michael; Wright, Alan J.; Kettunen, Mikko I.; Kennedy, Brett W. C.; Larkin, Timothy J.; Dzien, Piotr; Marco-Rius, Irene; Bohndiek, Sarah E.; Brindle, Kevin M.

    2017-01-01

    Rapid cancer cell proliferation promotes the production of reducing equivalents, which counteract the effects of relatively high levels of reactive oxygen species. Reactive oxygen species levels increase in response to chemotherapy and cell death, whereas an increase in antioxidant capacity can confer resistance to chemotherapy and is associated with an aggressive tumor phenotype. The pentose phosphate pathway is a major site of NADPH production in the cell, which is used to maintain the main intracellular antioxidant, glutathione, in its reduced state. Previous studies have shown that the rate of hyperpolarized [1-13C]dehydroascorbic acid (DHA) reduction, which can be measured in vivo using non-invasive 13C magnetic resonance spectroscopic imaging, is increased in tumors and that this is correlated with the levels of reduced glutathione. We show here that the rate of hyperpolarized [1-13C]DHA reduction is increased in tumors that have been oxidatively prestressed by depleting the glutathione pool by buthionine sulfoximine treatment. This increase was associated with a corresponding increase in pentose phosphate pathway flux, assessed using 13C-labeled glucose, and an increase in glutaredoxin activity, which catalyzes the glutathione-dependent reduction of DHA. These results show that the rate of DHA reduction depends not only on the level of reduced glutathione, but also on the rate of NADPH production, contradicting the conclusions of some previous studies. Hyperpolarized [1-13C]DHA can be used, therefore, to assess the capacity of tumor cells to resist oxidative stress in vivo. However, DHA administration resulted in transient respiratory arrest and cardiac depression, which may prevent translation to the clinic. PMID:27994059

  14. Galactic Chemical Evolution: The Impact of the 13C-pocket Structure on the s-process Distribution

    NASA Astrophysics Data System (ADS)

    Bisterzo, S.; Travaglio, C.; Wiescher, M.; Käppeler, F.; Gallino, R.

    2017-01-01

    The solar s-process abundances have been analyzed in the framework of a Galactic Chemical Evolution (GCE) model. The aim of this work is to implement the study by Bisterzo et al., who investigated the effect of one of the major uncertainties of asymptotic giant branch (AGB) yields, the internal structure of the 13C pocket. We present GCE predictions of s-process elements computed with additional tests in the light of suggestions provided in recent publications. The analysis is extended to different metallicities, by comparing GCE results and updated spectroscopic observations of unevolved field stars. We verify that the GCE predictions obtained with different tests may represent, on average, the evolution of selected neutron-capture elements in the Galaxy. The impact of an additional weak s-process contribution from fast-rotating massive stars is also explored.

  15. Local structure and molecular motions in imidazolium hydrogen malonate crystal as studied by 2H and 13C NMR

    NASA Astrophysics Data System (ADS)

    Mizuno, M.; Chizuwa, M.; Umiyama, T.; Kumagai, Y.; Miyatou, T.; Ohashi, R.; Ida, T.; Tansho, M.; Shimizu, T.

    2015-04-01

    The local structure and molecular motion of the imidazolium hydrogen malonate crystal were investigated using solid-state 2H and 13C NMR. The imidazolium ion undergoes isotropic rotation, which is correlated with a defect in the crystal, as observed by 2H NMR broadline spectra above 263 K. A 180∘ flip of the imidazolium ion in the regular site was observed from 2H NMR quadrupole Carr-Purcell-Meiboom-Gill (QCPMG) spectra. The Grotthuss mechanism was accompanied by a 180∘ flip of the imidazolium ion in regular sites. Moreover, the proton transfer associated with the imidazolium ion of the defective crystal is important for proton conductivity of the imidazolium hydrogen malonate crystal.

  16. Rovibrational constants of the ground state and v8 = 1 state of 13C2HD3 by high-resolution FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Ng, L. L.; Tan, T. L.

    2016-06-01

    The Fourier transform infrared (FTIR) spectrum of the c-type ν8 band of 13C2HD3 was recorded for the first time at a unapodized resolution of 0.0063 cm-1 in the wavenumber region of 830-1000 cm-1. Through the fitting of a total of 1057 assigned infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation, rovibrational constants for the upper state (v8 = 1) up to five quartic centrifugal distortion terms were derived for the first time with a root-mean-square (rms) deviation of 0.00073 cm-1. The band center of ν8 of 13C2HD3 was found to be 913.011021(55) cm-1. Ground state rovibrational constants up to five quartic terms of 13C2HD3 were also determined from a fit of 453 ground state combination-differences from the present infrared measurements with an rms deviation of 0.00072 cm-1 for the first time. The uncertainty of the measured infrared lines was estimated to be ±0.0012 cm-1. From the ground state rotational constants, the inertial defect of 13C2HD3 was calculated to be 0.06973(16) uÅ2, showing the high planarity of the molecule.

  17. 2H-DNP-enhanced 2H–13C solid-state NMR correlation spectroscopy

    PubMed Central

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

    2015-01-01

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

  18. Real-time assessment of Krebs cycle metabolism using hyperpolarized 13C magnetic resonance spectroscopy.

    PubMed

    Schroeder, Marie A; Atherton, Helen J; Ball, Daniel R; Cole, Mark A; Heather, Lisa C; Griffin, Julian L; Clarke, Kieran; Radda, George K; Tyler, Damian J

    2009-08-01

    The Krebs cycle plays a fundamental role in cardiac energy production and is often implicated in the energetic imbalance characteristic of heart disease. In this study, we measured Krebs cycle flux in real time in perfused rat hearts using hyperpolarized magnetic resonance spectroscopy (MRS). [2-(13)C]Pyruvate was hyperpolarized and infused into isolated perfused hearts in both healthy and postischemic metabolic states. We followed the enzymatic conversion of pyruvate to lactate, acetylcarnitine, citrate, and glutamate with 1 s temporal resolution. The appearance of (13)C-labeled glutamate was delayed compared with that of other metabolites, indicating that Krebs cycle flux can be measured directly. The production of (13)C-labeled citrate and glutamate was decreased postischemia, as opposed to lactate, which was significantly elevated. These results showed that the control and fluxes of the Krebs cycle in heart disease can be studied using hyperpolarized [2-(13)C]pyruvate.

  19. Nanotwins soften boron-rich boron carbide (B13C2)

    NASA Astrophysics Data System (ADS)

    An, Qi; Goddard, William A.

    2017-03-01

    Extensive studies of metals and alloys have observed that nanotwins lead to strengthening, but the role of nanotwins in ceramics is not well established. We compare here the shear strength and the deformation mechanism of nanotwinned boron-rich boron carbide (B13C2) with the perfect crystal under both pure shear and biaxial shear deformations. We find that the intrinsic shear strength of crystalline B13C2 is higher than that of crystalline boron carbide (B4C). But nanotwins in B13C2 lower the strength, making it softer than crystalline B4C. This reduction in strength of nanotwinned B13C2 arises from the interaction of the twin boundary with the C-B-C chains that connect the B12 icosahedra.

  20. Strongly polarizing weakly coupled 13C nuclear spins with optically pumped nitrogen-vacancy center

    PubMed Central

    Wang, Ping; Liu, Bao; Yang, Wen

    2015-01-01

    Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has recently attracted widespread attention due to its various applications. Here we present an analytical formula that not only provides a clear physical picture for the recently observed polarization reversal of strongly coupled13C nuclei over a narrow range of magnetic field [H. J. Wang et al., Nat. Commun. 4, 1940 (2013)], but also demonstrates the possibility to strongly polarize weakly coupled13C nuclei. This allows sensitive magnetic field control of the 13C nuclear spin polarization for NMR applications and significant suppression of the 13C nuclear spin noise to prolong the NV spin coherence time. PMID:26521962

  1. Deposition of 13C tracer in the JET MkII-HD divertor

    NASA Astrophysics Data System (ADS)

    Jet-Efda Contributors Likonen, J.; Hakola, A.; Strachan, J.; Coad, J. P.; Widdowson, A.; Koivuranta, S.; Hole, D. E.; Mizohata, K.; Rubel, M.; Jachmich, S.; Stamp, M.

    2011-08-01

    Migration of 13C has been investigated at JET by puffing 13CH4 into the outer midplane at the end of the 2007 campaign. The 13C deposition profile was measured with secondary ion mass spectrometry (SIMS) and Rutherford backscattering (RBS) techniques. 13C was mainly found on Tile 1 and near the outer strike point (OSP) on Tile 7. The 13C transport was modelled with the EDGE2D/NIMBUS code. Previous work indicates that migration pathways are: (1) through the main chamber scrape-off layer (SOL), (2) migration through the private flux region (PFR) aided by E × B drifts and (3) neutral migration originating near the strike points. The main contribution of this paper is to further describe the neutral migration.

  2. Preparation of 13C/15N-labeled oligomers using the polymerase chain reaction

    DOEpatents

    Chen, Xian; Gupta, Goutam; Bradbury, E. Morton

    2001-01-01

    Preparation of .sup.13 C/.sup.15 N-labeled DNA oligomers using the polymerase chain reaction (PCR). A PCR based method for uniform (.sup.13 C/.sup.15 N)-labeling of DNA duplexes is described. Multiple copies of a blunt-ended duplex are cloned into a plasmid, each copy containing the sequence of interest and restriction Hinc II sequences at both the 5' and 3' ends. PCR using bi-directional primers and uniformly .sup.13 C/.sup.15 N-labeled dNTP precursors generates labeled DNA duplexes containing multiple copies of the sequence of interest. Twenty-four cycles of PCR, followed by restriction and purification, gave the uniformly .sup.13 C/.sup.15 N-labeled duplex sequence with a 30% yield. Such labeled duplexes find significant applications in multinuclear magnetic resonance spectroscopy.

  3. Separation of extra- and intracellular metabolites using hyperpolarized 13C diffusion weighted MR

    NASA Astrophysics Data System (ADS)

    Koelsch, Bertram L.; Sriram, Renuka; Keshari, Kayvan R.; Leon Swisher, Christine; Van Criekinge, Mark; Sukumar, Subramaniam; Vigneron, Daniel B.; Wang, Zhen J.; Larson, Peder E. Z.; Kurhanewicz, John

    2016-09-01

    This work demonstrates the separation of extra- and intracellular components of glycolytic metabolites with diffusion weighted hyperpolarized 13C magnetic resonance spectroscopy. Using b-values of up to 15,000 s mm-2, a multi-exponential signal response was measured for hyperpolarized [1-13C] pyruvate and lactate. By fitting the fast and slow asymptotes of these curves, their extra- and intracellular weighted diffusion coefficients were determined in cells perfused in a MR compatible bioreactor. In addition to measuring intracellular weighted diffusion, extra- and intracellular weighted hyperpolarized 13C metabolites pools are assessed in real-time, including their modulation with inhibition of monocarboxylate transporters. These studies demonstrate the ability to simultaneously assess membrane transport in addition to enzymatic activity with the use of diffusion weighted hyperpolarized 13C MR. This technique could be an indispensible tool to evaluate the impact of microenvironment on the presence, aggressiveness and metastatic potential of a variety of cancers.

  4. Abundance Anomaly of the 13C Isotopic Species of c-C3H2 in the Low-mass Star Formation Region L1527

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Sakai, Nami; Tokudome, Tomoya; López-Sepulcre, Ana; Watanabe, Yoshimasa; Takano, Shuro; Lefloch, Bertrand; Ceccarelli, Cecilia; Bachiller, Rafael; Caux, Emmanuel; Vastel, Charlotte; Yamamoto, Satoshi

    2015-07-01

    The rotational spectral lines of c-C3H2 and two kinds of the 13C isotopic species, c-{}13{{CCCH}}2 ({C}2v symmetry) and c-{{CC}}13{{CH}}2 (Cs symmetry), have been observed in the 1-3 mm band toward the low-mass star-forming region L1527. We have detected 7, 3, and 6 lines of c-C3H2, c-{}13{{CCCH}}2, and c-{{CC}}13{{CH}}2, respectively, with the Nobeyama 45 m telescope and 34, 6, and 13 lines, respectively, with the IRAM 30 m telescope, where seven, two, and two transitions, respectively, are observed with both telescopes. With these data, we have evaluated the column densities of the normal and 13C isotopic species. The [c-C3H2]/[c-{}13{{CCCH}}2] ratio is determined to be 310 ± 80, while the [c-C3H2]/[c-{{CC}}13{{CH}}2] ratio is determined to be 61 ± 11. The [c-C3H2]/[c-{}13{{CCCH}}2] and [c-C3H2]/[c-{{CC}}13{{CH}}2] ratios expected from the elemental 12C/13C ratio are 60-70 and 30-35, respectively, where the latter takes into account the statistical factor of 2 for the two equivalent carbon atoms in c-C3H2. Hence, this observation further confirms the dilution of the 13C species in carbon-chain molecules and their related molecules, which are thought to originate from the dilution of 13C+ in the gas-phase C+ due to the isotope exchange reaction: {}13{{{C}}}++{CO}\\to {}13{CO}+{{{C}}}+. Moreover, the abundances of the two 13C isotopic species are different from each other. The ratio of c-{}13{{CCCH}}2 species relative to c-{{CC}}13{{CH}}2 is determined to be 0.20 ± 0.05. If 13C were randomly substituted for the three carbon atoms, the [c-{}13{{CCCH}}2]/[c-{{CC}}13{{CH}}2] ratio would be 0.5. Hence, the observed ratio indicates that c-{{CC}}13{{CH}}2 exists more favorably. Possible origins of the different abundances are discussed. Based on observations carried out with the IRAM 30 m Telescope and the NRO 45 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). NRO is a branch of the National Astronomical Observatory of Japan

  5. Water availability and branch length determine delta(13)C in foliage of Pinus pinaster.

    PubMed

    Warren, Charles R.; Adams, Mark A.

    2000-05-01

    The stable carbon isotope composition (delta(13)C) of foliage integrates signals resulting from environmental and hydraulic constraints on water movement and photosynthesis. We used branch length as a simple predictor of hydraulic constraints to water fluxes and determined the response of delta(13)C to varying water availability. Foliage up to 6 years old was taken from Pinus pinaster Ait. trees growing at four sites differing in precipitation (P; 414-984 mm year(-1)) and potential evaporation (ET; 1091-1750 mm year(-1)). Branch length was the principal determinant of temporal trends in delta(13)C. The strong relationship between delta(13)C and branch length was a function of hydraulic conductance, which was negatively correlated with branch length (r(2) = 0.84). Variation in P and ET among sites was reflected in delta(13)C, which was negatively correlated with P/ET (r(2) = 0.66). However, this analysis was confounded by differences in branch length. If the effects of branch length on delta(13)C were first removed, then the 'residual' delta(13)C was more closely related to P/ET (r(2) = 0.99), highlighting the importance of accounting for variation in hydraulic constraints to water flux between sites and years. For plant species that exhibit considerable phenotypic plasticity in response to changes in environment (e.g., variation in leaf area, branch length and number, or stem form), the environmental effects on delta(13)C in foliage can only be reliably assessed if deconvoluted from hydraulic constraints.

  6. Parallel labeling experiments validate Clostridium acetobutylicum metabolic network model for (13)C metabolic flux analysis.

    PubMed

    Au, Jennifer; Choi, Jungik; Jones, Shawn W; Venkataramanan, Keerthi P; Antoniewicz, Maciek R

    2014-11-01

    In this work, we provide new insights into the metabolism of Clostridium acetobutylicum ATCC 824 obtained using a systematic approach for quantifying fluxes based on parallel labeling experiments and (13)C-metabolic flux analysis ((13)C-MFA). Here, cells were grown in parallel cultures with [1-(13)C]glucose and [U-(13)C]glucose as tracers and (13)C-MFA was used to quantify intracellular metabolic fluxes. Several metabolic network models were compared: an initial model based on current knowledge, and extended network models that included additional reactions that improved the fits of experimental data. While the initial network model did not produce a statistically acceptable fit of (13)C-labeling data, an extended network model with five additional reactions was able to fit all data with 292 redundant measurements. The model was subsequently trimmed to produce a minimal network model of C. acetobutylicum for (13)C-MFA, which could still reproduce all of the experimental data. The flux results provided valuable new insights into the metabolism of C. acetobutylicum. First, we found that TCA cycle was effectively incomplete, as there was no measurable flux between α-ketoglutarate and succinyl-CoA, succinate and fumarate, and malate and oxaloacetate. Second, an active pathway was identified from pyruvate to fumarate via aspartate. Third, we found that isoleucine was produced exclusively through the citramalate synthase pathway in C. acetobutylicum and that CAC3174 was likely responsible for citramalate synthase activity. These model predictions were confirmed in several follow-up tracer experiments. The validated metabolic network model established in this study can be used in future investigations for unbiased (13)C-flux measurements in C. acetobutylicum.

  7. Tracing the biosynthetic source of essential amino acids in marine turtles using delta13C fingerprints.

    PubMed

    Arthur, Karen E; Kelez, Shaleyla; Larsen, Thomas; Choy, C Anela; Popp, Brian N

    2014-05-01

    Plants, bacteria, and fungi produce essential amino acids (EAAs) with distinctive patterns of delta13C values that can be used as naturally occurring fingerprints of biosynthetic origin of EAAs in a food web. Because animals cannot synthesize EAAs and must obtain them from food, their tissues reflect delta13C(EAA) patterns found in diet, but it is not known how microbes responsible for hindgut fermentation in some herbivores influence the delta13C values of EAAs in their hosts' tissues. We examined whether distinctive delta13C fingerprints of hindgut flora are evident in the tissues of green turtles (Chelonia mydas), which are known to be facultative hindgut fermenters. We determined delta13C(EAA) values in tissues of green turtles foraging herbivorously in neritic habitats of Hawaii and compared them with those from green, olive ridley, and loggerhead turtles foraging carnivorously in oceanic environments of the central and southeast Pacific Ocean. Results of multivariate statistical analysis revealed two distinct groups that could be distinguished based on unique delta13C(EAA) patterns. A three-end-member predictive linear discriminant model indicated that delta13C(EAA) fingerprints existed in the tissues of carnivorous turtles that resembled patterns found in microalgae, which form the base of an oceanic food web, whereas herbivorous turtles derive EAAs from a bacterial or seagrass source. This study demonstrates the capacity for delta13C fingerprinting to establish the biosynthetic origin of EAAs in higher consumers, and that marine turtles foraging on macroalgal diets appear to receive nutritional supplementation from bacterial symbionts in their digestive system.

  8. Multi-year estimates of plant and ecosystem 13C discrimination at AmeriFlux sites

    NASA Astrophysics Data System (ADS)

    Dang, X.; Lai, C.; Hollinger, D. Y.; Bush, S.; Randerson, J. T.; Law, B. E.; Schauer, A. J.; Ehleringer, J.

    2011-12-01

    We estimated plant and ecosystem 13C discrimination continuously at 8 AmeriFlux sites (Howland Forest, Harvard Forest, Wind River Forest, Rannells Prairie, Freeman Ranch, Chestnut Ridge, Metolius, and Marys River fir) over 8 years (2002-2009). We used an observation-based approach from weekly measurements of eddy covariance CO2 fluxes and their 13C/12C ratios to estimate photosynthetic 13C discrimination (△A) and respiration (δ13CR) on seasonal and interannual time scales. The coordinated, systematic flask sampling across the AmeriFlux subnetwork were used for cross-site synthesis of monthly flux estimates [Dang et al. Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over 4 flux towers in the U.S.A., Journal of Geophysical Research-Biogeosciences, in press]. Here, we evaluated environmental factors that also influenced temporal variability in △A and δ13CR from daily to interannual time scales, comparing atmospheric 13C/12C measurements, leaf and needle organic matter, and tree ring cellulose. Across these major biomes that dominate the continent, we show differential ecophysiological responses to environmental stresses, among which water availability appeared to be a dominant factor. Our decadal measurement period provided robust estimates of atmospheric 13C discrimination by terrestrial ecosystems, but also suggest regions where enhanced monitoring efforts are required (e.g., 13C/12C emission from fire and urban metabolism; increased temporal resolution of 13C measurements in stress-sensitive ecosystems) to make atmospheric 13C/12C measurements an effective constraint for continental-scale assessments of the terrestrial carbon cycle.

  9. Soil compaction effects on water status of ponderosa pine assessed through 13C/12C composition.

    PubMed

    Gomez, G Armando; Singer, Michael J; Powers, Robert F; Horwath, William R

    2002-05-01

    Soil compaction is a side effect of forest reestablishment practices resulting from use of heavy equipment and site preparation. Soil compaction often alters soil properties resulting in changes in plant-available water. The use of pressure chamber methods to assess plant water stress has two drawbacks: (1) the measurements are not integrative; and (2) the method is difficult to apply extensively to establish seasonal soil water status. We evaluated leaf carbon isotopic composition (delta13C) as a means of assessing effects of soil compaction on water status and growth of young ponderosa pine (Pinus ponderosa var. ponderosa Dougl. ex Laws) stands across a range of soil textures. Leaf delta13C in cellulose and whole foliar tissue were highly correlated. Leaf delta13C in both whole tissue and cellulose (holocellulose) was up to 1.0 per thousand lower in trees growing in non-compacted (NC) loam or clay soils than in compacted (SC) loam or clay soils. Soil compaction had the opposite effect on leaf delta13C in trees growing on sandy loam soil, indicating that compaction increased water availability in this soil type. Tree growth response to compaction also varied with soil texture, with no effect, a negative effect and a positive effect as a result of compaction of loam, clay and sandy loam soils, respectively. There was a significant correlation between 13C signature and tree growth along the range of soil textures. Leaf delta13C trends were correlated with midday stem water potentials. We conclude that leaf delta13C can be used to measure retrospective water status and to assess the impact of site preparation on tree growth. The advantage of the leaf delta13C approach is that it provides an integrative assessment of past water status in different aged leaves.

  10. The effect of chemical processing on the δ 13C value of plant tissue

    NASA Astrophysics Data System (ADS)

    Van de Water, Peter K.

    2002-04-01

    The effect of standard processing techniques on the δ 13C value of plant tissue was tested using species representing the three photosynthetic pathways, including angiosperms and gymnosperms within the C 3 taxonomic division. The species include Cowania mexicana (C 3 angiosperm), Juniperus osteosperma (C 3 gymnosperm), Opuntia spp. (crassulacean acid metabolism [CAM] angiosperm), and Atriplex canescens (C 4 angiosperm). Each species is represented by 5 plants collected at two different sites, for a total of 10 samples. The samples were processed to whole plant tissue, holocellulose, α-cellulose, and nitrocellulose. An additional process was added with the discovery of residual Ca-oxalate crystals in holocellulose samples. Both C 3 species show δ 13C values becoming 13C enriched with increased processing. The CAM representative shows the opposite trend, with 13C depletion during the progression of treatments. The greatest range of values and most inconsistent trends occur in the C 4 representative. Removal of the Ca-oxalate fraction resulted in different mean weight percentages and δ 13C values among the species. Calculated δ 13C values of the Ca-oxalate crystals show depletion from the tissue values in the two C 3 species and enrichment in the C 4 and CAM representatives. The C. mexicana samples show the greatest change between the tissue and Ca-oxalates (7.3‰) but the least mean weight percentage (11%), whereas A. canescens shows the greatest overall change, with a -2.8‰ isotopic shift and over 48% mean weight percentage. Variability within the samples undergoing each treatment remained relatively unchanged even with increased cellulose purity. This paper provides estimates of isotopic offsets necessary to correct from one treatment to another. Significant differences in δ 13C among different treatments confirm the need to state the tissue fraction analyzed when reporting δ 13C results.

  11. Detection of human muscle glycogen by natural abundance /sup 13/C NMR

    SciTech Connect

    Avison, M.J.; Rothman, D.L.; Nadel, E.; Shulman, R.G.

    1988-03-01

    Natural abundance /sup 13/C nuclear magnetic resonance spectroscopy was used to detect signals from glycogen in the human gastrocnemius muscle. The reproducibility of the measurement was demonstrated, and the ability to detect dynamic changes was confirmed by measuring a decrease in muscle glycogen levels after exercise and its subsequent repletion. Single frequency gated /sup 1/H decoupling was used to obtain decoupled natural abundance /sup 13/C NMR spectra of the C-1 position of muscle glycogen.

  12. (13) C dynamic nuclear polarization using isotopically enriched 4-oxo-TEMPO free radicals.

    PubMed

    Niedbalski, Peter; Parish, Christopher; Kiswandhi, Andhika; Lumata, Lloyd

    2016-12-01

    The nitroxide-based free radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) is a widely used polarizing agent in NMR signal amplification via dissolution dynamic nuclear polarization (DNP). In this study, we have thoroughly investigated the effects of (15) N and/or (2) H isotopic labeling of 4-oxo-TEMPO free radical on (13) C DNP of 3 M [1-(13) C] sodium acetate samples in 1 : 1 v/v glycerol : water at 3.35 T and 1.2 K. Four variants of this free radical were used for (13) C DNP: 4-oxo-TEMPO, 4-oxo-TEMPO-(15) N, 4-oxo-TEMPO-d16 and 4-oxo-TEMPO-(15) N,d16 . Our results indicate that, despite the striking differences seen in the electron spin resonance (ESR) spectral features, the (13) C DNP efficiency of these (15) N and/or (2) H-enriched 4-oxo-TEMPO free radicals are relatively the same compared with (13) C DNP performance of the regular 4-oxo-TEMPO. Furthermore, when fully deuterated glassing solvents were used, the (13) C DNP signals of these samples all doubled in the same manner, and the (13) C polarization buildup was faster by a factor of 2 for all samples. The data here suggest that the hyperfine coupling contributions of these isotopically enriched 4-oxo-TEMPO free radicals have negligible effects on the (13) C DNP efficiency at 3.35 T and 1.2 K. These results are discussed in light of the spin temperature model of DNP. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Concentric Rings K-Space Trajectory for Hyperpolarized 13C MR Spectroscopic Imaging

    PubMed Central

    Jiang, Wenwen; Lustig, Michael; Larson, Peder E.Z.

    2014-01-01

    Purpose To develop a robust and rapid imaging technique for hyperpolarized 13C MR Spectroscopic Imaging (MRSI) and investigate its performance. Methods A concentric rings readout trajectory with constant angular velocity is proposed for hyperpolarized 13C spectroscopic imaging and its properties are analyzed. Quantitative analyses of design tradeoffs are presented for several imaging scenarios. The first application of concentric rings on 13C phantoms and in vivo animal hyperpolarized 13C MRSI studies were performed to demonstrate the feasibility of the proposed method. Finally, a parallel imaging accelerated concentric rings study is presented. Results The concentric rings MRSI trajectory has the advantages of acquisition timesaving compared to echo-planar spectroscopic imaging (EPSI). It provides sufficient spectral bandwidth with relatively high SNR efficiency compared to EPSI and spiral techniques. Phantom and in vivo animal studies showed good image quality with half the scan time and reduced pulsatile flow artifacts compared to EPSI. Parallel imaging accelerated concentric rings showed advantages over Cartesian sampling in g-factor simulations and demonstrated aliasing-free image quality in a hyperpolarized 13C in vivo study. Conclusion The concentric rings trajectory is a robust and rapid imaging technique that fits very well with the speed, bandwidth, and resolution requirements of hyperpolarized 13C MRSI. PMID:25533653

  14. Tracing carbon monoxide uptake by Clostridium ljungdahlii during ethanol fermentation using (13)C-enrichment technique.

    PubMed

    Yun, Seok-In; Gang, Seong-Joo; Ro, Hee-Myong; Lee, Min-Jin; Choi, Woo-Jung; Hong, Seong-Gu; Kang, Kwon-Kyoo

    2013-05-01

    Conversion of synthesis gas (CO and H2) to ethanol can be an alternative, promising technology to produce biofuels from renewable biomass. To distinguish microbial utilization of carbon source between fructose and synthesis gas CO and to evaluate biological production of ethanol from CO, we adopted the (13)C-enrichment of the CO substrate and hypothesized that the residual increase in δ(13)C of the cell biomass would reflect the increased contribution of (13)C-enriched CO. Addition of synthesis gas to live culture medium for ethanol fermentation by Clostridum ljungdahlii increased the microbial growth and ethanol production. Despite the high (13)C-enrichment in CO (99 atom % (13)C), however, microbial δ(13)C increased relatively small compared to the microbial growth. The uptake efficiency of CO estimated using the isotope mass balance equation was also very low: 0.0014 % for the low CO and 0.0016 % for the high CO treatment. Furthermore, the fast production of ethanol in the early stage indicated that the presence of sugar in fermentation medium would limit the utilization of CO as a carbon source by C. ljungdahlii.

  15. Extreme (13)C depletion of carbonates formed during oxidation of biogenic methane in fractured granite.

    PubMed

    Drake, Henrik; Åström, Mats E; Heim, Christine; Broman, Curt; Åström, Jan; Whitehouse, Martin; Ivarsson, Magnus; Siljeström, Sandra; Sjövall, Peter

    2015-05-07

    Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C13C as light as -69‰ V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in carbon-poor deep groundwater in fractured granitoid rocks has resulted in fracture-wall precipitation of the most extremely 13C-depleted carbonates ever reported, δ13C down to -125‰ V-PDB. A microbial consortium of sulphate reducers and methane oxidizers has been involved, as revealed by biomarker signatures in the carbonates and S-isotope compositions of co-genetic sulphide. Methane formed at shallow depths has been oxidized at several hundred metres depth at the transition to a deep-seated sulphate-rich saline water. This process is so far an unrecognized terrestrial sink of methane.

  16. Extreme 13C depletion of carbonates formed during oxidation of biogenic methane in fractured granite

    PubMed Central

    Drake, Henrik; Åström, Mats E.; Heim, Christine; Broman, Curt; Åström, Jan; Whitehouse, Martin; Ivarsson, Magnus; Siljeström, Sandra; Sjövall, Peter

    2015-01-01

    Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C13C as light as −69‰ V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in carbon-poor deep groundwater in fractured granitoid rocks has resulted in fracture-wall precipitation of the most extremely 13C-depleted carbonates ever reported, δ13C down to −125‰ V-PDB. A microbial consortium of sulphate reducers and methane oxidizers has been involved, as revealed by biomarker signatures in the carbonates and S-isotope compositions of co-genetic sulphide. Methane formed at shallow depths has been oxidized at several hundred metres depth at the transition to a deep-seated sulphate-rich saline water. This process is so far an unrecognized terrestrial sink of methane. PMID:25948095

  17. Extreme 13C depletion of carbonates formed during oxidation of biogenic methane in fractured granite

    NASA Astrophysics Data System (ADS)

    Drake, Henrik; Åström, Mats E.; Heim, Christine; Broman, Curt; Åström, Jan; Whitehouse, Martin; Ivarsson, Magnus; Siljeström, Sandra; Sjövall, Peter

    2015-05-01

    Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C13C as light as -69‰ V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in carbon-poor deep groundwater in fractured granitoid rocks has resulted in fracture-wall precipitation of the most extremely 13C-depleted carbonates ever reported, δ13C down to -125‰ V-PDB. A microbial consortium of sulphate reducers and methane oxidizers has been involved, as revealed by biomarker signatures in the carbonates and S-isotope compositions of co-genetic sulphide. Methane formed at shallow depths has been oxidized at several hundred metres depth at the transition to a deep-seated sulphate-rich saline water. This process is so far an unrecognized terrestrial sink of methane.

  18. 13C-labelled microdialysis studies of cerebral metabolism in TBI patients☆

    PubMed Central

    Carpenter, Keri L.H.; Jalloh, Ibrahim; Gallagher, Clare N.; Grice, Peter; Howe, Duncan J.; Mason, Andrew; Timofeev, Ivan; Helmy, Adel; Murphy, Michael P.; Menon, David K.; Kirkpatrick, Peter J.; Carpenter, T. Adrian; Sutherland, Garnette R.; Pickard, John D.; Hutchinson, Peter J.

    2014-01-01

    Human brain chemistry is incompletely understood and better methodologies are needed. Traumatic brain injury (TBI) causes metabolic perturbations, one result of which includes increased brain lactate levels. Attention has largely focussed on glycolysis, whereby glucose is converted to pyruvate and lactate, and is proposed to act as an energy source by feeding into neurons’ tricarboxylic acid (TCA) cycle, generating ATP. Also reportedly upregulated by TBI is the pentose phosphate pathway (PPP) that does not generate ATP but produces various molecules that are putatively neuroprotective, antioxidant and reparative, in addition to lactate among the end products. We have developed a novel combination of 13C-labelled cerebral microdialysis both to deliver 13C-labelled substrates into brains of TBI patients and recover the 13C-labelled metabolites, with high-resolution 13C NMR analysis of the microdialysates. This methodology has enabled us to achieve the first direct demonstration in humans that the brain can utilise lactate via the TCA cycle. We are currently using this methodology to make the first direct comparison of glycolysis and the PPP in human brain. In this article, we consider the application of 13C-labelled cerebral microdialysis for studying brain energy metabolism in patients. We set this methodology within the context of metabolic pathways in the brain, and 13C research modalities addressing them. PMID:24361470

  19. sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: I. Patterns

    SciTech Connect

    McConnaughey, T. )

    1989-01-01

    Biological carbonates frequently precipitate out of {sup 18}O and {sup 13}C equilibrium with ambient waters. Two patterns of isotopic disequilibrium are particularly common. Kinetic disequilibria, so designated because they apparently result from kinetic isotope effects during CO{sub 2} hydration and hydroxylation, involve simultaneous depletions of {sup 18}O and {sup 13}C as large as 4{per thousand} and 10 to 15{per thousand}, respectively. Rapid skeletogenesis favors strong kinetic effects, and approximately linear correlations between skeletal {delta}{sup 18}O and {delta}{sup 13}C are common in carbonates showing mainly the kinetic pattern. Metabolic effects involve additional positive or negative modulation of skeletal {delta}{sup 13}C, reflecting changes in the {delta}{sup 13}C of dissolved inorganic carbon, caused mainly by photosynthesis and respiration. Kinetic isotope disequilibria tend to be fairly consistent in rapidly growing parts of photosynthetic corals, and time dependent isotopic variations therefore reflect changes in environmental conditions. {delta}{sup 18}O variations from Galapagos corals yields meaningful clues regarding seawater temperature, while {delta}{sup 13}C variations reflect changes in photosynthesis, modulated by cloudiness.

  20. The paper trail of the 13C of atmospheric CO2 since the industrial revolution period

    NASA Astrophysics Data System (ADS)

    Yakir, Dan

    2011-07-01

    The 13C concentration in atmospheric CO2 has been declining over the past 150 years as large quantities of 13C-depleted CO2 from fossil fuel burning are added to the atmosphere. Deforestation and other land use changes have also contributed to the trend. Looking at the 13C variations in the atmosphere and in annual growth rings of trees allows us to estimate CO2 uptake by land plants and the ocean, and assess the response of plants to climate. Here I show that the effects of the declining 13C trend in atmospheric CO2 are recorded in the isotopic composition of paper used in the printing industry, which provides a well-organized archive and integrated material derived from trees' cellulose. 13C analyses of paper from two European and two American publications showed, on average, a - 1.65 ± 1.00‰ trend between 1880 and 2000, compared with - 1.45 and - 1.57‰ for air and tree-ring analyses, respectively. The greater decrease in plant-derived 13C in the paper we tested than in the air is consistent with predicted global-scale increases in plant intrinsic water-use efficiency over the 20th century. Distinct deviations from the atmospheric trend were observed in both European and American publications immediately following the World War II period.

  1. (13) C Breath Tests Are Feasible in Patients With Extracorporeal Membrane Oxygenation Devices.

    PubMed

    Bednarsch, Jan; Menk, Mario; Malinowski, Maciej; Weber-Carstens, Steffen; Pratschke, Johann; Stockmann, Martin

    2016-07-01

    Temporary extracorporeal membrane oxygenation (ECMO) has been established as an essential part of therapy in patients with pulmonary or cardiac failure. As physiological gaseous exchange is artificially altered in this patient group, it is debatable whether a (13) C-breath test can be carried out. In this proof of technical feasibility report, we assess the viability of the (13) C-breath test LiMAx (maximum liver function capacity) in patients on ECMO therapy. All breath probes for the test device were obtained directly via the membrane oxygenator. Data of four patients receiving liver function assessment with the (13) C-breath test LiMAx while having ECMO therapy were analyzed. All results were compared with validated scenarios of the testing procedures. The LiMAx test could successfully be carried out in every case without changing ECMO settings. Clinical course of the patients ranging from multiorgan failure to no sign of liver insufficiency was in accordance with the results of the LiMAx liver function test. The (13) C-breath test is technically feasible in the context of ECMO. Further evaluation of (13) C-breath test in general would be worthwhile. The LiMAx test as a (13) C-breath test accessing liver function might be of particular predictive interest if patients with ECMO therapy develop multiorgan failure.

  2. (13)C-labelled microdialysis studies of cerebral metabolism in TBI patients.

    PubMed

    Carpenter, Keri L H; Jalloh, Ibrahim; Gallagher, Clare N; Grice, Peter; Howe, Duncan J; Mason, Andrew; Timofeev, Ivan; Helmy, Adel; Murphy, Michael P; Menon, David K; Kirkpatrick, Peter J; Carpenter, T Adrian; Sutherland, Garnette R; Pickard, John D; Hutchinson, Peter J

    2014-06-16

    Human brain chemistry is incompletely understood and better methodologies are needed. Traumatic brain injury (TBI) causes metabolic perturbations, one result of which includes increased brain lactate levels. Attention has largely focussed on glycolysis, whereby glucose is converted to pyruvate and lactate, and is proposed to act as an energy source by feeding into neurons' tricarboxylic acid (TCA) cycle, generating ATP. Also reportedly upregulated by TBI is the pentose phosphate pathway (PPP) that does not generate ATP but produces various molecules that are putatively neuroprotective, antioxidant and reparative, in addition to lactate among the end products. We have developed a novel combination of (13)C-labelled cerebral microdialysis both to deliver (13)C-labelled substrates into brains of TBI patients and recover the (13)C-labelled metabolites, with high-resolution (13)C NMR analysis of the microdialysates. This methodology has enabled us to achieve the first direct demonstration in humans that the brain can utilise lactate via the TCA cycle. We are currently using this methodology to make the first direct comparison of glycolysis and the PPP in human brain. In this article, we consider the application of (13)C-labelled cerebral microdialysis for studying brain energy metabolism in patients. We set this methodology within the context of metabolic pathways in the brain, and (13)C research modalities addressing them.

  3. OEDGE Modeling of {sup 13}C Deposition in the Inner Divertor of DIII-D

    SciTech Connect

    Elder, J; Stangeby, P; Whyte, D; Allen, S; McLean, A; Boedo, J; Bray, B; Brooks, N; Fenstermacher, M; Groth, M; Lasnier, C; Lisgo, S; Rudakov, D; Wampler, W; Watkins, J; West, W

    2004-12-01

    Use of carbon in tokamaks leads to a major tritium retention issue due to co-deposition. To investigate this process a low power (no beams) L-mode experiment was performed on DIII-D in which {sup 13}CH{sub 4} was puffed into the main vessel through the toroidally-symmetric pumping plenum at the top of lower single-null discharges. Subsequently, the {sup 13}C content of tiles taken from the vessel wall was measured. The interpretive OEDGE code was used to model the results. It was found that the {sup 13}C deposition pattern is controlled by: (a) source strength of {sup 13}C{sup +}, (b) radial location of the {sup 13}C{sup +} source, (c) D{sub {perpendicular}}, (d) M{sub {parallel}}, the scrape-off layer parallel Mach number. Best agreement was found for (a) {approx}50% conversion efficiency {sup 13}CH{sub 4} {yields} {sup 13}C{sup +}, (b) {sup 13}C{sup +} source {approx}3.5 cm outboard of separatrix near {sup 13}CH{sub 4} injection location, (c)D{sub {perpendicular}} {approx} 0.3 m{sup 2}s{sup -1}, (d) M{sub {parallel}} {approx} 0.4 toward inside.

  4. High-Resolution Infrared Spectra of the ν_1 Fundamental Bands of 13C Mono-Substituted Propyne in a Supersonic Slit Jet

    NASA Astrophysics Data System (ADS)

    Zhao, Dongfeng; Doney, Kirstin D.; Linnartz, Harold

    2014-06-01

    In the past few decades, many high-resolution spectroscopic studies have been dedicated to the C-H stretch vibrations in propyne (CH_3-C≡CH), aiming to understand the intramolecular vibrational redistribution in isolated small hydrocarbons. In this talk, we present the sensitive detection of the ν_1 (acetylenic C-H stretch) fundamental bands of the three 13C mono-substituted isotopologues of propyne. The infrared absorption spectra are recorded using continuous-wave cavity ring-down spectroscopy (CRDS) in combination with a supersonic jet expansion of propyne/argon gas mixtures. A 0.05x30 mm slit nozzle is used in the present experiment to realize an effective rotational cooling to ≈14 K and a reduced Doppler width of ≈90 MHz. The high sensitivity of CRDS allows us to detect the three 13C isotopologues in their 1.1% natural abundance. Different infrared band intensities of ν_1 are found for the three isotopologues. Detailed rotational analyses of the experimental spectra are performed to derive effective spectroscopic constants for the upper ν_1 vibrational state. The 13C-substitution effect of the near/non-resonant perturbations to ν_1 of propyne is discussed. In addition, more accurate infrared data of 12C-propyne, including the ν_1 fundamental band, are also obtained from our experimental spectra.

  5. Determination of glucan phosphorylation using heteronuclear 1H, 13C double and 1H, 13C, 31P triple-resonance NMR spectra.

    PubMed

    Schmieder, Peter; Nitschke, Felix; Steup, Martin; Mallow, Keven; Specker, Edgar

    2013-10-01

    Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear (1) H,(13) C and (1) H,(13) C,(31) P techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples.

  6. Interference effects between /sup 17/O states populated in the /sup 13/C(/sup 6/Li,d)/sup 17/O*. --> cap alpha. +/sup 13/C reaction

    SciTech Connect

    Cardella, G.; Cunsolo, A.; Foti, A.; Imme, G.; Pappalardo, G.; Raciti, G.; Rizzo, F.; Alamanos, N.; Berthier, B.; Saunier, N.

    1987-12-01

    An analysis of the /sup 13/C(/sup 6/Li,d..cap alpha..)/sup 13/C reaction in the collinear (theta/sub d/ = 0/sup 0/) and noncollinear (theta/sub d/ = 10/sup 0/,8/sup 0/) geometry is made for two peaks observed in the deuteron energy spectrum and corresponding to excitation energies of 16.1 and 13.6 MeV in the /sup 17/O nucleus. It is shown that the reaction proceeds via a direct alpha-transfer process which populates doublets of interfering /sup 17/O levels. Spins, weights, and parities of these levels are obtained by means of a least square procedure.

  7. The use of dynamic nuclear polarization (13)C-pyruvate MRS in cancer.

    PubMed

    Gutte, Henrik; Hansen, Adam Espe; Johannesen, Helle Hjorth; Clemmensen, Andreas Ettrup; Ardenkjær-Larsen, Jan Henrik; Nielsen, Carsten Haagen; Kjær, Andreas

    2015-01-01

    In recent years there has been an immense development of new targeted anti-cancer drugs. For practicing precision medicine, a sensitive method imaging for non-invasive, assessment of early treatment response and for assisting in developing new drugs is warranted. Magnetic Resonance Spectroscopy (MRS) is a potent technique for non-invasive in vivo investigation of tissue chemistry and cellular metabolism. Hyperpolarization by Dynamic Nuclear Polarization (DNP) is capable of creating solutions of molecules with polarized nuclear spins in a range of biological molecules and has enabled the real-time investigation of in vivo metabolism. The development of this new method has been demonstrated to enhance the nuclear polarization more than 10,000-fold, thereby significantly increasing the sensitivity of the MRS with a spatial resolution to the millimeters and a temporal resolution at the subsecond range. Furthermore, the method enables measuring kinetics of conversion of substrates into cell metabolites and can be integrated with anatomical proton magnetic resonance imaging (MRI). Many nuclei and substrates have been hyperpolarized using the DNP method. Currently, the most widely used compound is (13)C-pyruvate due to favoring technicalities. Intravenous injection of the hyperpolarized (13)C-pyruvate results in appearance of (13)C-lactate, (13)C-alanine and (13)C-bicarbonate resonance peaks depending on the tissue, disease and the metabolic state probed. In cancer, the lactate level is increased due to increased glycolysis. The use of DNP enhanced (13)C-pyruvate has in preclinical studies shown to be a sensitive method for detecting cancer and for assessment of early treatment response in a variety of cancers. Recently, a first-in-man 31-patient study was conducted with the primary objective to assess the safety of hyperpolarized (13)C-pyruvate in healthy subjects and prostate cancer patients. The study showed an elevated (13)C-lactate/(13)C-pyruvate ratio in regions of

  8. The use of dynamic nuclear polarization 13C-pyruvate MRS in cancer

    PubMed Central

    Gutte, Henrik; Hansen, Adam Espe; Johannesen, Helle Hjorth; Clemmensen, Andreas Ettrup; Ardenkjær-Larsen, Jan Henrik; Nielsen, Carsten Haagen; Kjær, Andreas

    2015-01-01

    In recent years there has been an immense development of new targeted anti-cancer drugs. For practicing precision medicine, a sensitive method imaging for non-invasive, assessment of early treatment response and for assisting in developing new drugs is warranted. Magnetic Resonance Spectroscopy (MRS) is a potent technique for non-invasive in vivo investigation of tissue chemistry and cellular metabolism. Hyperpolarization by Dynamic Nuclear Polarization (DNP) is capable of creating solutions of molecules with polarized nuclear spins in a range of biological molecules and has enabled the real-time investigation of in vivo metabolism. The development of this new method has been demonstrated to enhance the nuclear polarization more than 10,000-fold, thereby significantly increasing the sensitivity of the MRS with a spatial resolution to the millimeters and a temporal resolution at the subsecond range. Furthermore, the method enables measuring kinetics of conversion of substrates into cell metabolites and can be integrated with anatomical proton magnetic resonance imaging (MRI). Many nuclei and substrates have been hyperpolarized using the DNP method. Currently, the most widely used compound is 13C-pyruvate due to favoring technicalities. Intravenous injection of the hyperpolarized 13C-pyruvate results in appearance of 13C-lactate, 13C-alanine and 13C-bicarbonate resonance peaks depending on the tissue, disease and the metabolic state probed. In cancer, the lactate level is increased due to increased glycolysis. The use of DNP enhanced 13C-pyruvate has in preclinical studies shown to be a sensitive method for detecting cancer and for assessment of early treatment response in a variety of cancers. Recently, a first-in-man 31-patient study was conducted with the primary objective to assess the safety of hyperpolarized 13C-pyruvate in healthy subjects and prostate cancer patients. The study showed an elevated 13C-lactate/13C-pyruvate ratio in regions of biopsy

  9. Paleoclimate Reconstruction From the d13C Organic and d13C Carbonate Proxies in Triassic Paleosols and Sediments, Ischigualasto Basin Argentina

    NASA Astrophysics Data System (ADS)

    Moore, K. A.; Tabor, N. J.; Montañez, I. P.; Currie, B.; Shipman, T.

    2001-12-01

    Stable carbon isotopes of organic matter and paleosol carbonate from the Triassic Ischigualasto Formation, Argentina are used as a proxy of paleoatmospheric pCO2 and d13CO2. Carbon and Oxygen isotope values were determined for over 100 Triassic pedogenic carbonate nodules and associated organic matter. The d13C of carbonate ranges from -3.29 per mil to -10.56 per mil. The d13C of organic matter ranges from -21.07 per mil to -24.24 per mil. The Hydrogen and Oxygen indices and TOC values indicate that the best preserved organic matter samples yield the most negative d13C values. Reconstructed pCO2 levels were around 1000 ppm V in the early to mid- Triassic and increased to around 2000 ppm V later in the Triassic. This maximum is followed by a fall in pCO2 in the late Triassic. This previously undocumented rapid change in paleo-CO2 levels likely accompanied the evolution of mammal-like reptiles to true dinosaurs as well as rapid climate change.

  10. Metabolite channeling and compartmentation in the human cell line AGE1.HN determined by 13C labeling experiments and 13C metabolic flux analysis.

    PubMed

    Niklas, Jens; Sandig, Volker; Heinzle, Elmar

    2011-12-01

    This study focused on analyzing active pathways and the metabolic flux distribution in human neuronal AGE1.HN cells that is a desirable basis for a rational design and optimization of producing cell lines and production processes for biopharmaceuticals. (13)C-labeling experiments and (13)C metabolic flux analysis were conducted using glucose, glutamine, alanine and lactate tracers in parallel experiments. Connections between cytosolic and mitochondrial metabolite pools were verified, e.g., flux from TCA cycle metabolite (13)C to glycolytic metabolites. It was also found that lactate and alanine are produced from the same pyruvate pool and that consumed alanine is mainly directly metabolized and secreted as lactate. Activity of the pentose phosphate pathway was low being around 2.3% of the glucose uptake flux. This might be compensated in AGE1.HN by high mitochondrial malic enzyme flux producing NADPH. Mitochondrial pyruvate transport was almost zero. Instead pyruvate carbons were channeled via oxaloacetate into the TCA cycle which was mainly fed via α-ketoglutarate and oxaloacetate during the investigated phase. The data indicate that further optimization of this cell line should focus on the improved substrate usage which can be accomplished by an improved connectivity between glycolytic and mitochondrial pyruvate pools or by better control of the substrate uptake.

  11. On the use of phloem sap δ13C to estimate canopy carbon discrimination

    NASA Astrophysics Data System (ADS)

    Rascher, Katherine; Máguas, Cristina; Werner, Christiane

    2010-05-01

    Although the carbon stable isotope composition (d13C) of bulk leaf material is a good integrative parameter of photosynthetic discrimination and can be used as a reliable ecological index of plant functioning; it is not a good tracer of short-term changes in photosynthetic discrimination. In contrast, d13C of phloem sap is potentially useful as an indicator of short-term changes in canopy photosynthetic discrimination. However, recent research indicates that d13C signatures may be substantially altered by metabolic processes downstream of initial leaf-level carbon fixation (e.g. post-photosynthetic fractionation). Accordingly, before phloem sap d13C can be used as a proxy for canopy level carbon discrimination an understanding of factors influencing the degree and magnitude of post-photosynthetic fractionation and how these vary between species is of paramount importance. In this study, we measured the d13C signature along the basipetal transport pathway in two co-occurring tree species in the field - an understory invasive exotic legume, Acacia longifolia, and a native pine, Pinus pinaster. We measured d13C of bulk leaf and leaf water soluble organic matter (WSOM), phloem sap sampled at two points along the plant axis and leaf and root dark respiration. In general, species differences in photosynthetic discrimination resulted in more enriched d13C values in the water-conserving P. pinaster relative to the water-spending A. longifolia. Post-photosynthetic fractionation led to differences in d13C of carbon pools along the plant axis with progressively more depleted d13C from the canopy to the trunk (~6.5 per mil depletion in A. longifolia and ~0.8per mil depletion in P. pinaster). Leaf and root respiration, d13C, were consistently enriched relative to putative substrates. We hypothesize that the pronounced enrichment of leaf respired CO2 relative to leaf WSOM may have left behind relatively depleted carbon to be loaded into the phloem resulting in d13C depletion

  12. 13C-phenylalanine breath test detects altered phenylalanine kinetics in schizophrenia patients

    PubMed Central

    Teraishi, T; Ozeki, Y; Hori, H; Sasayama, D; Chiba, S; Yamamoto, N; Tanaka, H; Iijima, Y; Matsuo, J; Kawamoto, Y; Kinoshita, Y; Hattori, K; Ota, M; Kajiwara, M; Terada, S; Higuchi, T; Kunugi, H

    2012-01-01

    Phenylalanine is an essential amino acid required for the synthesis of catecholamines including dopamine. Altered levels of phenylalanine and its metabolites in blood and cerebrospinal fluid have been reported in schizophrenia patients. This study attempted to examine for the first time whether phenylalanine kinetics is altered in schizophrenia using L-[1-13C]phenylalanine breath test (13C-PBT). The subjects were 20 chronically medicated schizophrenia patients (DSM-IV) and the same number of age- and sex-matched controls. 13C-phenylalanine (99 atom% 13C; 100 mg) was administered orally and the breath 13CO2 /12CO2 ratio was monitored for 120 min. The possible effect of antipsychotic medication (risperidone (RPD) or haloperidol (HPD) treatment for 21 days) on 13C-PBT was examined in rats. Body weight (BW), age and diagnostic status were significant predictors of the area under the curve of the time course of Δ13CO2 (‰) and the cumulative recovery rate (CRR) at 120 min. A repeated measures analysis of covariance controlled for age and BW revealed that the patterns of CRR change over time differed between the patients and controls and that Δ13CO2 was lower in the patients than in the controls at all sampling time points during the 120 min test, with an overall significant difference between the two groups. Chronic administration of RPD or HPD had no significant effect on 13C-PBT indices in rats. Our results suggest that 13C-PBT is a novel laboratory test that can detect altered phenylalanine kinetics in chronic schizophrenia patients. Animal experiments suggest that the observed changes are unlikely to be attributable to antipsychotic medication. PMID:22832963

  13. 13C/12C isotope ratio MS analysis of testosterone, in chemicals and pharmaceutical preparations.

    PubMed

    de la Torre, X; González, J C; Pichini, S; Pascual, J A; Segura, J

    2001-02-01

    The 13C/12C ratio can be used to detect testosterone misuse in sport because (semi)-synthetic testosterone is supposed to have a 13C abundance different from that of endogenous natural human testosterone. In this study, gas chromatography/combustion isotope ratio mass spectrometry (GC/C/IRMS) analysis for the measurement of the delta 13C/1000 value of testosterone from esterified forms of 13 pharmaceutical preparations, six reagent grade chemicals and three bulk materials (raw materials used in pharmaceutical proarations) obtained world-wide was investigated after applying a strong acidic solvolytic procedure. Mean delta 13C/1000 values of non esterified (free) testosterone from chemicals and bulk materials of several testosterone esters were in the range: -25.91/-32.82/1000 while the value obtained for a (semi)-synthetic, reagent grade, free testosterone was -27.36/1000. The delta 13C/1000 results obtained for testosterone from the pharmaceuticals investigated containing testosterone esters were quite homogeneous (mean and S.D. of delta 13C/1000 values of free testosterone: 27.43 +/- 0.76/1000), being the range between -26.18 and -30.04/1000. Values described above were clearly different from those reported by several authors for endogenous natural human testosterone and its main metabolites excreted into the urine in non-consumers of testosterone (delta 13C/1000 range: from -21.3 to -24.4/1000), while they were similar to those of urinary testosterone and metabolites from individuals treated with testosterone esters and testosterone precursors. This finding justifies the fact that administration of these pharmaceutical formulations led to a statistical decrease of carbon isotope ratio of urinary testosterone and its main metabolites in treated subjects.

  14. An overview of methods using 13C for improved compound identification in metabolomics and natural products

    PubMed Central

    Clendinen, Chaevien S.; Stupp, Gregory S.; Ajredini, Ramadan; Lee-McMullen, Brittany; Beecher, Chris; Edison, Arthur S.

    2015-01-01

    Compound identification is a major bottleneck in metabolomics studies. In nuclear magnetic resonance (NMR) investigations, resonance overlap often hinders unambiguous database matching or de novo compound identification. In liquid chromatography-mass spectrometry (LC-MS), discriminating between biological signals and background artifacts and reliable determination of molecular formulae are not always straightforward. We have designed and implemented several NMR and LC-MS approaches that utilize 13C, either enriched or at natural abundance, in metabolomics applications. For LC-MS applications, we describe a technique called isotopic ratio outlier analysis (IROA), which utilizes samples that are isotopically labeled with 5% (test) and 95% (control) 13C. This labeling strategy leads to characteristic isotopic patterns that allow the differentiation of biological signals from artifacts and yield the exact number of carbons, significantly reducing possible molecular formulae. The relative abundance between the test and control samples for every IROA feature can be determined simply by integrating the peaks that arise from the 5 and 95% channels. For NMR applications, we describe two 13C-based approaches. For samples at natural abundance, we have developed a workflow to obtain 13C–13C and 13C–1H statistical correlations using 1D 13C and 1H NMR spectra. For samples that can be isotopically labeled, we describe another NMR approach to obtain direct 13C–13C spectroscopic correlations. These methods both provide extensive information about the carbon framework of compounds in the mixture for either database matching or de novo compound identification. We also discuss strategies in which 13C NMR can be used to identify unknown compounds from IROA experiments. By combining technologies with the same samples, we can identify important biomarkers and corresponding metabolites of interest. PMID:26379677

  15. Ecological processes dominate the 13C land disequilibrium in a Rocky Mountain subalpine forest

    NASA Astrophysics Data System (ADS)

    Bowling, D. R.; Ballantyne, A. P.; Miller, J. B.; Burns, S. P.; Conway, T. J.; Menzer, O.; Stephens, B. B.; Vaughn, B. H.

    2014-04-01

    Fossil fuel combustion has increased atmospheric CO2 by ≈ 115 µmol mol-1 since 1750 and decreased its carbon isotope composition (δ13C) by 1.7-2‰ (the 13C Suess effect). Because carbon is stored in the terrestrial biosphere for decades and longer, the δ13C of CO2 released by terrestrial ecosystems is expected to differ from the δ13C of CO2 assimilated by land plants during photosynthesis. This isotopic difference between land-atmosphere respiration (δR) and photosynthetic assimilation (δA) fluxes gives rise to the 13C land disequilibrium (D). Contemporary understanding suggests that over annual and longer time scales, D is determined primarily by the Suess effect, and thus, D is generally positive (δR > δA). A 7 year record of biosphere-atmosphere carbon exchange was used to evaluate the seasonality of δA and δR, and the 13C land disequilibrium, in a subalpine conifer forest. A novel isotopic mixing model was employed to determine the δ13C of net land-atmosphere exchange during day and night and combined with tower-based flux observations to assess δA and δR. The disequilibrium varied seasonally and when flux-weighted was opposite in sign than expected from the Suess effect (D = -0.75 ± 0.21‰ or -0.88 ± 0.10‰ depending on method). Seasonality in D appeared to be driven by photosynthetic discrimination (Δcanopy) responding to environmental factors. Possible explanations for negative D include (1) changes in Δcanopy over decades as CO2 and temperature have risen, and/or (2) post-photosynthetic fractionation processes leading to sequestration of isotopically enriched carbon in long-lived pools like wood and soil.

  16. Age-related variations in delta(13)C of ecosystem respiration across a coniferous forest chronosequence in the Pacific Northwest.

    PubMed

    Fessenden, Julianna E; Ehleringer, James R

    2002-02-01

    We tested the hypothesis that forest age influences the carbon isotope ratio (delta13C) of carbon reservoirs and CO2 at local and regional levels. Carbon isotope ratios of ecosystem respiration (delta13C(R)), soil respiration (delta13C(R-soil)), bulk needle tissue (delta13C(P)) and soil organic carbon (delta(13)C(SOC)) were measured in > 450-, 40- and 20-year-old temperate, mixed coniferous forests in southern Washington, USA. Values of delta13C(R), delta13C(R-soil), delta13C(P) and delta13C(SOC) showed consistent enrichment with increasing stand age. Between the youngest and oldest forests there was an approximately 1 per thousand enrichment in delta13C(P) (at similar canopy levels), delta13C(SOC) (throughout the soil column), delta13C(R-soil) (during the wet season) and delta13C(R) (during the dry season). Mean values of delta13C(R) were -25.9, -26.5 and -27.0 per thousand for the 450-, 40- and 20-year-old forests, respectively. Both delta13C(R-soil) and the difference between delta13C(R) and delta13C(R-soil) were more 13C enriched in older forests than in young forest: delta13C(R) - delta13C(R-soil) = 2.3, 1.1 and 0.5 per thousand for the 450-, 40- and 20-year-old forests, respectively. Values of delta(13)C(P) were proportionally more depleted relative to delta13C(R): delta13C(R) - delta13C(P) = 0.5, 2.2 and 2.5 per thousand for the 450-, 40- and 20-year-old forests, respectively. Values of delta13C(P) were most 13C-enriched at the top of the canopy and in the oldest forest regardless of season (overall values were -26.9, -28.7 and -29.4 per thousand for the 450-, 40- and 20-year-old forests, respectively). Values of delta13C(SOC) from shallow soil depths were similar to delta13C(P) values of upper- and mid-canopy needles. All delta13C data are consistent with the hypothesis that a decrease in stomatal conductance associated with decreased hydraulic conductance leads to increased CO2 diffusional limitations in older coniferous trees. The strong associations

  17. High-resolution FTIR spectroscopic analysis of the ν11 and ν2 + ν7 bands of 13C2D4

    NASA Astrophysics Data System (ADS)

    Gabona, M. G.; Tan, T. L.

    2016-06-01

    The FTIR spectrum of the ν11 band of 13C2D4 was recorded at a resolution of 0.0063 cm-1 in the 2130-2250 cm-1 region. This band was perturbed by the unobserved ν2 + ν7 band. By fitting 862 infrared transitions for the ν11 band with a rms deviation of 0.0024 cm-1 using a Watson's A-reduced Hamiltonian in the Ir representation including a Coriolis coupling constant, the rovibrational constants for the ν11 = 1 state and three rotational constants for the ν2 = ν7 = 1 state of 13C2D4 were derived for the first time. The band centers of ν11 and ν2 + ν7 were determined to be 2193.75982(25) cm-1 and 2184.613(11) cm-1 respectively.

  18. 13C-CPMAS and 1H-NMR study of the inclusion complexes of beta-cyclodextrin with carvacrol, thymol, and eugenol prepared in supercritical carbon dioxide.

    PubMed

    Locci, Emanuela; Lai, Simona; Piras, Alessandra; Marongiu, Bruno; Lai, Adolfo

    2004-09-01

    Beta-cyclodextrin (beta-CD) inclusion complexes with carvacrol (1), thymol (2), and eugenol (3) (components of essential oils of vegetable origin) were prepared by the supercritical CO2 technique, and their structural characterization was achieved by means of 1H-NMR in aqueous solution and 13C-CPMAS NMR in the solid state. Evidence of the formation of the inclusion complexes for all the examined systems was obtained by 1H-NMR in solution, while 2D-ROESY-NMR experiments were used to investigate the geometry of inclusion. In addition, the dynamics of these inclusion complexes in the kHz timescale was investigated by analysis of the 1H and 13C spin-lattice relaxation times in the rotating frame.

  19. 13C CP MAS NMR and GIAO-CHF/DFT calculations of flavonoids: Morin, kaempferol, tricin, genistein, formononetin and 3,7-dihydroxyflavone

    NASA Astrophysics Data System (ADS)

    Zielińska, Agnieszka; Paradowska, Katarzyna; Jakowski, Jacek; Wawer, Iwona

    2008-02-01

    13C CP MAS NMR spectra of the flavonoids: morin, kaempferol, 3,7-dihydroxyflavone, tricin and isoflavones: genistein and formononetin were recorded to characterize solid-state conformations. Intramolecular hydrogen bonds forming five-, six- and seven-membered rings are present in the two morin molecules in the crystals - their 13C resonances have been assigned with the aid of the calculated shielding constants. Linear relationships between the calculated shielding constants σDFT (ppm) and chemical shifts ( δCPMAS, ppm) were obtained for all studied compounds. Higher correlation coefficients suggest that the conformation with "clockwise" orientation of both OH groups is more probable in the solid 3,7-dihydroxyflavone, whereas in the solid formononetin the OH and OCH 3 substituents are directed "anticlockwise". The barrier to the rotation of phenyl ring B decreases in the order: morin (2'-OH, 3-OH) > kaempferol (3-OH) > tricin.

  20. s-processing in AGB stars revisited. I. Does the main component constrain the neutron source in the {sup 13}C pocket?

    SciTech Connect

    Trippella, O.; Busso, M.; Maiorca, E.; Käppeler, F.; Palmerini, S. E-mail: maurizio.busso@fisica.unipg.it

    2014-05-20

    Slow neutron captures at A ≳ 85 are mainly guaranteed by the reaction {sup 13}C(α,n){sup 16}O in asymptotic giant branch (AGB) stars, requiring proton injections from the envelope. These were so far assumed to involve a small mass (≲ 10{sup –3} M {sub ☉}), but models with rotation suggest that in such tiny layers excessive {sup 14}N hampers s-processing. Furthermore, s-element abundances in galaxies require {sup 13}C-rich layers substantially extended in mass (≳ 4 × 10{sup –3} M {sub ☉}). We therefore present new calculations aimed at clarifying those issues and at understanding whether the solar composition helps to constrain the {sup 13}C 'pocket' extension. We show that: (1) mixing 'from bottom to top' (as in magnetic buoyancy or other forced mechanisms) can form a {sup 13}C reservoir substantially larger than assumed so far, covering most of the He-rich layers; (2) on the basis of this idea, stellar models at a fixed metallicity reproduce the main s-component as accurately as before; and (3) they make nuclear contributions from unknown nucleosynthesis processes (LEPP) unnecessary, against common assumptions. These models also avoid problems of mixing at the envelope border and fulfil requirements from C-star luminosities. They yield a large production of nuclei below A = 100, so that {sup 86,} {sup 87}Sr may be fully synthesized by AGB stars, while {sup 88}Sr, {sup 89}Y, and {sup 94}Zr are contributed more efficiently than before. Finally, we suggest tests suitable for providing a final answer regarding the extension of the {sup 13}C pocket.

  1. Temperature peaking at beginning of breakdown in 2.45 GHz pulsed off-resonance electron cyclotron resonance ion source hydrogen plasma

    SciTech Connect

    Cortazar, O. D.

    2012-10-15

    An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 {mu}s are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas.

  2. Comparison of sustained off-resonance irradiation collisionally activated dissociation and multipole storage-assisted dissociation for top-down protein analysis

    SciTech Connect

    Keller, Karin M; Brodbelt, Jennifer S; Hettich, Robert {Bob} L; Van Berkel, Gary J

    2004-01-01

    Tandem mass spectrometric data acquired for small (8--18 kDa) intact proteins by sustained off-resonance irradiation collisionally activated dissociation (SORI-CAD) and multipole storage-assisted dissociation (MSAD) were compared, and the results indicate that the two activation methods do not always provide the same fragmentation patterns. In MSAD experiments, the charge state distribution made available by the ionization conditions may dictate the range of fragment ions that can be generated. In addition, conditions of high space charge within the hexapole impair transmission and/or trapping of high m/z species, which can result in loss of important precursor and product ions. Finally, the non-resonant nature of activation in MSAD can provide access to secondary dissociation processes that are not available by SORI. Because of these considerations, MSAD is less reliable than SORI for generating sequence tag data. However, it appears that MSAD samples 'preferred' cleavage processes (i.e. those occurring at D and P residues) just as well as SORI, which implies that MSAD data may be somewhat more compatible with search algorithms that utilize unprocessed fragment ion masses.

  3. Multi-objective experimental design for (13)C-based metabolic flux analysis.

    PubMed

    Bouvin, Jeroen; Cajot, Simon; D'Huys, Pieter-Jan; Ampofo-Asiama, Jerry; Anné, Jozef; Van Impe, Jan; Geeraerd, Annemie; Bernaerts, Kristel

    2015-10-01

    (13)C-based metabolic flux analysis is an excellent technique to resolve fluxes in the central carbon metabolism but costs can be significant when using specialized tracers. This work presents a framework for cost-effective design of (13)C-tracer experiments, illustrated on two different networks. Linear and non-linear optimal input mixtures are computed for networks for Streptomyces lividans and a carcinoma cell line. If only glucose tracers are considered as labeled substrate for a carcinoma cell line or S. lividans, the best parameter estimation accuracy is obtained by mixtures containing high amounts of 1,2-(13)C2 glucose combined with uniformly labeled glucose. Experimental designs are evaluated based on a linear (D-criterion) and non-linear approach (S-criterion). Both approaches generate almost the same input mixture, however, the linear approach is favored due to its low computational effort. The high amount of 1,2-(13)C2 glucose in the optimal designs coincides with a high experimental cost, which is further enhanced when labeling is introduced in glutamine and aspartate tracers. Multi-objective optimization gives the possibility to assess experimental quality and cost at the same time and can reveal excellent compromise experiments. For example, the combination of 100% 1,2-(13)C2 glucose with 100% position one labeled glutamine and the combination of 100% 1,2-(13)C2 glucose with 100% uniformly labeled glutamine perform equally well for the carcinoma cell line, but the first mixture offers a decrease in cost of $ 120 per ml-scale cell culture experiment. We demonstrated the validity of a multi-objective linear approach to perform optimal experimental designs for the non-linear problem of (13)C-metabolic flux analysis. Tools and a workflow are provided to perform multi-objective design. The effortless calculation of the D-criterion can be exploited to perform high-throughput screening of possible (13)C-tracers, while the illustrated benefit of multi

  4. Anaerobic Methane Oxidation in Soils - revealed using 13C-labelled methane tracers

    NASA Astrophysics Data System (ADS)

    Riekie, G. J.; Baggs, E. M.; Killham, K. S.; Smith, J. U.

    2008-12-01

    In marine sediments, anaerobic methane oxidation is a significant biogeochemical process limiting methane flux from ocean to atmosphere. To date, evidence for anaerobic methane oxidation in terrestrial environments has proved elusive, and its significance is uncertain. In this study, an isotope dilution method specifically designed to detect the process of anaerobic methane oxidation in methanogenic wetland soils is applied. Methane emissions of soils from three contrasting permanently waterlogged sites in Scotland are investigated in strictly anoxic microcosms to which 13C- labelled methane is added, and changes in the concentration and 12C/13C isotope ratios of methane and carbon dioxide are subsequently measured and used to calculate separate the separate components of the methane flux. The method used takes into account the 13C-methane associated with methanogenesis, and the amount of methane dissolved in the soil. The calculations make no prior assumptions about the kinetics of methane production or oxidation. The results indicate that methane oxidation can take place in anoxic soil environments. The clearest evidence for anaerobic methane oxidation is provided by soils from a minerotrophic fen site (pH 6.0) in Bin Forest underlain by ultra-basic and serpentine till. In the fresh soil anoxic microcosms, net consumption methane was observed, and the amount of headspace 13C-CO2 increased at a greater rate than the 12+13C-CO2, further proof of methane oxidation. A net increase in methane was measured in microcosms of soil from Murder Moss, an alkaline site, pH 6.5, with a strong calcareous influence. However, the 13C-CH4 data provided evidence of methane oxidation, both in the disappearance of C- CH4 and appearance of smaller quantities of 13C-CO2. The least alkaline (pH 5.5) microcosms, of Gateside Farm soil - a granitic till - exhibited net methanogenesis and the changes in 13C-CH4 and 13C-CO2 here followed the pattern expected if no methane is consumed

  5. Monitoring electron donor metabolism under variable electron acceptor conditions using 13C-labeled lactate

    NASA Astrophysics Data System (ADS)

    Bill, M.; Conrad, M. E.; Yang, L.; Beller, H. R.; Brodie, E. L.

    2010-12-01

    Three sets of flow-through columns constructed with aquifer sediment from Hanford (WA) were used to study reduction of Cr(VI) to poorly soluble Cr(III) under denitrifying, sulfate-reducing/fermentative, and iron-reducing conditions with lactate as the electron donor. In order to understand the relationship between electron donors and biomarkers, and to determine the differences in carbon isotope fractionation resulting from different microbial metabolic processes, we monitored the variation in carbon isotopes in dissolved inorganic carbon (DIC), in total organic carbon (TOC), and in lactate, acetate and propionate. The greatest enrichment in 13C in columns was observed under denitrifying conditions. The δ13C of DIC increased by ~1750 to ~2000‰ fifteen days after supplementation of natural abundance lactate with a 13C-labeled lactate tracer (for an influent δ13C of ~2250‰ for the lactate) indicating almost complete oxidation of the electron donor. The denitrifying columns were among the most active columns and had the highest cell counts and the denitrification rate was highly correlated with Cr(VI) reduction rate. δ13C values of DIC ranged from ~540 to ~1170‰ for iron-reducing conditions. The lower enrichment in iron columns was related to the lower biological activity observed with lower yields of RNA and cell numbers in the column effluents. The carbon isotope shift in the sulfate-reducing ~198 to ~1960‰ for sulfate-reducing conditions reflecting the lower levels of the lactate in these columns. Additionally, in two of the sulfate columns, almost complete fermentation of the lactate occurred, producing acetate and propionate with the labeled carbon signature, but relatively smaller amounts of inorganic carbon. For all electron-accepting conditions, TOC yielded similar δ13C values as lactate stock solutions. Differences in C use efficiency, metabolic rate or metabolic pathway contributed to the differing TOC δ13C to DIC δ13C ratios between treatments

  6. A Method to Constrain Genome-Scale Models with 13C Labeling Data

    PubMed Central

    García Martín, Héctor; Kumar, Vinay Satish; Weaver, Daniel; Ghosh, Amit; Chubukov, Victor; Mukhopadhyay, Aindrila; Arkin, Adam; Keasling, Jay D.

    2015-01-01

    Current limitations in quantitatively predicting biological behavior hinder our efforts to engineer biological systems to produce biofuels and other desired chemicals. Here, we present a new method for calculating metabolic fluxes, key targets in metabolic engineering, that incorporates data from 13C labeling experiments and genome-scale models. The data from 13C labeling experiments provide strong flux constraints that eliminate the need to assume an evolutionary optimization principle such as the growth rate optimization assumption used in Flux Balance Analysis (FBA). This effective constraining is achieved by making the simple but biologically relevant assumption that flux flows from core to peripheral metabolism and does not flow back. The new method is significantly more robust than FBA with respect to errors in genome-scale model reconstruction. Furthermore, it can provide a comprehensive picture of metabolite balancing and predictions for unmeasured extracellular fluxes as constrained by 13C labeling data. A comparison shows that the results of this new method are similar to those found through 13C Metabolic Flux Analysis (13C MFA) for central carbon metabolism but, additionally, it provides flux estimates for peripheral metabolism. The extra validation gained by matching 48 relative labeling measurements is used to identify where and why several existing COnstraint Based Reconstruction and Analysis (COBRA) flux prediction algorithms fail. We demonstrate how to use this knowledge to refine these methods and improve their predictive capabilities. This method provides a reliable base upon which to improve the design of biological systems. PMID:26379153

  7. Production and NMR signal optimization of hyperpolarized 13C-labeled amino acids

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Ferguson, Sarah; Kiswandhi, Andhika; Lumata, Lloyd

    Amino acids are targeted nutrients for consumption by cancers to sustain their rapid growth and proliferation. 13C-enriched amino acids are important metabolic tracers for cancer diagnostics using nuclear magnetic resonance (NMR) spectroscopy. Despite this diagnostic potential, 13C NMR of amino acids however is hampered by the inherently low NMR sensitivity of the 13C nuclei. In this work, we have employed a physics technique known as dynamic nuclear polarization (DNP) to enhance the NMR signals of 13C-enriched amino acids. DNP works by transferring the high polarization of electrons to the nuclear spins via microwave irradiation at low temperature and high magnetic field. Using a fast dissolution method in which the frozen polarized samples are dissolved rapidly with superheated water, injectable solutions of 13C-amino acids with highly enhanced NMR signals (by at least 5,000-fold) were produced at room temperature. Factors that affect the NMR signal enhancement levels such as the choice of free radical polarizing agents and sample preparation will be discussed along with the thermal mixing physics model of DNP. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  8. A predictive tool for assessing (13)C NMR chemical shifts of flavonoids.

    PubMed

    Burns, Darcy C; Ellis, David A; March, Raymond E

    2007-10-01

    Herein are presented the (1)H and (13)C NMR data for seven monohydroxyflavones (3-, 5-, 6-, 7-, 2'-, 3'-, and 4'-hydroxyflavone), five dihydroxyflavones (3,2'-, 3,3'-, 3,4'-, 3,6-, 2',3'-dihydroxyflavone), a trihydroxyflavone (apigenin; 5,7,4'-trihydroxyflavone), a tetrahydroxyflavone (luteolin; 5,7,3',4'-tetrahydroxyflavone), and three glycosylated hydroxyflavones (orientin; luteolin-6C-beta-D-glucoside, homoorientin; luteolin-8C-beta-D-glucoside, vitexin; apigenin-8C-beta-D-glucoside). When these NMR spectra are compared, it is possible to assess the impact of flavone modification and to elucidate detailed structural and electronic information for these flavonoids. A simple predictive tool for assigning flavonoid (13)C chemical shifts, which is based on the cumulative differences between the monohydroxyflavones and flavone (13)C chemical shifts, is demonstrated. The tool can be used to accurately predict (13)C flavonoid chemical shifts and it is expected to be useful for rapid assessment of flavonoid (13)C NMR spectra and for assigning substitution patterns in newly isolated flavonoids.

  9. Global-mean marine δ13C and its uncertainty in a glacial state estimate

    NASA Astrophysics Data System (ADS)

    Gebbie, Geoffrey; Peterson, Carlye D.; Lisiecki, Lorraine E.; Spero, Howard J.

    2015-10-01

    A paleo-data compilation with 492 δ13C and δ18O observations provides the opportunity to better sample the Last Glacial Maximum (LGM) and infer its global properties, such as the mean δ13C of dissolved inorganic carbon. Here, the paleo-compilation is used to reconstruct a steady-state water-mass distribution for the LGM, that in turn is used to map the data onto a 3D global grid. A global-mean marine δ13C value and a self-consistent uncertainty estimate are derived using the framework of state estimation (i.e., combining a numerical model and observations). The LGM global-mean δ13C is estimated to be 0.14‰ ± 0.20‰ at the two standard error level, giving a glacial-to-modern change of 0.32‰ ± 0.20‰. The magnitude of the error bar is attributed to the uncertain glacial ocean circulation and the lack of observational constraints in the Pacific, Indian, and Southern Oceans. To halve the error bar, roughly four times more observations are needed, although strategic sampling may reduce this number. If dynamical constraints can be used to better characterize the LGM circulation, the error bar can also be reduced to 0.05 to 0.1‰, emphasizing that knowledge of the circulation is vital to accurately map δ13C in three dimensions.

  10. Hyperpolarized 13C dehydroascorbate as an endogenous redox sensor for in vivo metabolic imaging.

    PubMed

    Keshari, Kayvan R; Kurhanewicz, John; Bok, Robert; Larson, Peder E Z; Vigneron, Daniel B; Wilson, David M

    2011-11-15

    Reduction and oxidation (redox) chemistry is involved in both normal and abnormal cellular function, in processes as diverse as circadian rhythms and neurotransmission. Intracellular redox is maintained by coupled reactions involving NADPH, glutathione (GSH), and vitamin C, as well as their corresponding oxidized counterparts. In addition to functioning as enzyme cofactors, these reducing agents have a critical role in dealing with reactive oxygen species (ROS), the toxic products of oxidative metabolism seen as culprits in aging, neurodegenerative disease, and ischemia/ reperfusion injury. Despite this strong relationship between redox and human disease, methods to interrogate a redox pair in vivo are limited. Here we report the development of [1-(13)C] dehydroascorbate [DHA], the oxidized form of Vitamin C, as an endogenous redox sensor for in vivo imaging using hyperpolarized (13)C spectroscopy. In murine models, hyperpolarized [1-(13)C] DHA was rapidly converted to [1-(13)C] vitamin C within the liver, kidneys, and brain, as well as within tumor in a transgenic prostate cancer mouse. This result is consistent with what has been previously described for the DHA/Vitamin C redox pair, and points to a role for hyperpolarized [1-(13)C] DHA in characterizing the concentrations of key intracellular reducing agents, including GSH. More broadly, these findings suggest a prognostic role for this new redox sensor in determining vulnerability of both normal and abnormal tissues to ROS.

  11. Profiling human gut bacterial metabolism and its kinetics using [U-13C]glucose and NMR.

    PubMed

    de Graaf, Albert A; Maathuis, Annet; de Waard, Pieter; Deutz, Nicolaas E P; Dijkema, Cor; de Vos, Willem M; Venema, Koen

    2010-01-01

    This study introduces a stable-isotope metabolic approach employing [U-(13)C]glucose that, as a novelty, allows selective profiling of the human intestinal microbial metabolic products of carbohydrate food components, as well as the measurement of the kinetics of their formation pathways, in a single experiment. A well-established, validated in vitro model of human intestinal fermentation was inoculated with standardized gastrointestinal microbiota from volunteers. After culture stabilization, [U-(13)C]glucose was added as an isotopically labeled metabolic precursor. System lumen and dialysate samples were taken at regular intervals. Metabolite concentrations and isotopic labeling were determined by NMR, GC, and enzymatic methods. The main microbial metabolites were lactate, acetate, butyrate, formate, ethanol, and glycerol. They together accounted for a (13)C recovery rate as high as 91.2%. Using an NMR chemical shift prediction approach, several minor products that showed (13)C incorporation were identified as organic acids, amino acids, and various alcohols. Using computer modeling of the (12)C contents and (13)C labeling kinetics, the metabolic fluxes in the gut microbial pathways for synthesis of lactate, formate, acetate, and butyrate were determined separately for glucose and unlabeled background substrates. This novel approach enables the study of the modulation of human intestinal function by single nutrients, providing a new rational basis for achieving control of the short-chain fatty acids profile by manipulating substrate and microbiota composition in a purposeful manner.

  12. A Peptide-Based Method for 13C Metabolic Flux Analysis in Microbial Communities

    PubMed Central

    Ghosh, Amit; Nilmeier, Jerome; Weaver, Daniel; Adams, Paul D.; Keasling, Jay D.; Mukhopadhyay, Aindrila; Petzold, Christopher J.; Martín, Héctor García

    2014-01-01

    The study of intracellular metabolic fluxes and inter-species metabolite exchange for microbial communities is of crucial importance to understand and predict their behaviour. The most authoritative method of measuring intracellular fluxes, 13C Metabolic Flux Analysis (13C MFA), uses the labeling pattern obtained from metabolites (typically amino acids) during 13C labeling experiments to derive intracellular fluxes. However, these metabolite labeling patterns cannot easily be obtained for each of the members of the community. Here we propose a new type of 13C MFA that infers fluxes based on peptide labeling, instead of amino acid labeling. The advantage of this method resides in the fact that the peptide sequence can be used to identify the microbial species it originates from and, simultaneously, the peptide labeling can be used to infer intracellular metabolic fluxes. Peptide identity and labeling patterns can be obtained in a high-throughput manner from modern proteomics techniques. We show that, using this method, it is theoretically possible to recover intracellular metabolic fluxes in the same way as through the standard amino acid based 13C MFA, and quantify the amount of information lost as a consequence of using peptides instead of amino acids. We show that by using a relatively small number of peptides we can counter this information loss. We computationally tested this method with a well-characterized simple microbial community consisting of two species. PMID:25188426

  13. Emission of highly 13C-depleted methane from an upland blanket mire

    NASA Astrophysics Data System (ADS)

    Bowes, Helen L.; Hornibrook, Edward R. C.

    2006-02-01

    Rates and δ13C values of CH4 flux are reported from an upland blanket mire (Blaen Fign) situated in Wales UK. The δ13C values of CH4 flux were similar from Sphagnum and vascular flora dominated areas despite flux rates being an order of magnitude greater from the latter. Methane flux was 13C-depleted relative to belowground CH4, indicating that transport occurred predominately via passive diffusion through vascular flora and that pore water diffusion and ebullition contributed little to CH4 flux. The strong influence of vascular flora abundance on CH4 flux strength suggests that any factors altering vegetation assemblages in blanket mires will likely impact CH4 emission rates. Methane flux from Blaen Fign was highly 13C-depleted compared to emissions from minerotrophic wetlands, suggesting that δ13C values may be useful for tracing CH4 flux from blanket mires and other types of ombrogenous peatlands to the global CH4 budget.

  14. Ruminant Methane δ (13C/12C) - Values: Relation to Atmospheric Methane

    NASA Astrophysics Data System (ADS)

    Rust, Fleet

    1981-03-01

    The δ (13C/12C) - values of methane produced by fistulated steers, dairy cattle, and wethers, and dairy and beef cattle herds show a bimodal distribution that appears to be correlated with the plant type (C3 or C4, that is, producing either a three- or a four-carbon acid in the first step of photosynthesis) consumed by the animals. These results indicate that cattle and sheep, on a global basis, release methane with an average δ (13C/12C) value of -60 and -63 per mil, respectively. Together they are a source of atmospheric methane whose δ (13C/12C) is similar to published values for marsh gas and cannot explain the 20 per mil higher values for atmospheric methane.

  15. Parallel labeling experiments for pathway elucidation and (13)C metabolic flux analysis.

    PubMed

    Antoniewicz, Maciek R

    2015-12-01

    Metabolic pathway models provide the foundation for quantitative studies of cellular physiology through the measurement of intracellular metabolic fluxes. For model organisms metabolic models are well established, with many manually curated genome-scale model reconstructions, gene knockout studies and stable-isotope tracing studies. However, for non-model organisms a similar level of knowledge is often lacking. Compartmentation of cellular metabolism in eukaryotic systems also presents significant challenges for quantitative (13)C-metabolic flux analysis ((13)C-MFA). Recently, innovative (13)C-MFA approaches have been developed based on parallel labeling experiments, the use of multiple isotopic tracers and integrated data analysis, that allow more rigorous validation of pathway models and improved quantification of metabolic fluxes. Applications of these approaches open new research directions in metabolic engineering, biotechnology and medicine.

  16. Following Glycolysis Using 13C NMR: An Experiment Adaptable to Different Undergraduate Levels

    NASA Astrophysics Data System (ADS)

    Mega, T. L.; Carlson, C. B.; Cleary, D. A.

    1997-12-01

    This paper describes a laboratory exercise where the glycolysis of [1-13C] glucose under anaerobic conditions was followed using 13C NMR spectroscopy. The exercise is described in terms of its suitability for a variety of different undergraduate levels, although the emphasis in this paper is on its use in a n advanced chemistry laboratory course. The kinetics of the loss of glucose and the production of ethanol were investigated and found not to fit simple first or second order kinetics. In addition, the relative reaction rates of the two anomeric forms of glucose were analyzed, and it was determined that the a anomeric form reacted faster than the β anomeric form. Using proton-coupled 13C NMR, some of the metabolites were identified including ethanol (major) and glycerol (minor). Reaction and spectroscopic details are included.

  17. Anthropogenic and solar forcing in δ13C time pattern of coralline sponges.

    PubMed

    Madonia, Paolo; Reitner, Joachim

    2014-01-01

    We present the results of a re-analysis of a previously published carbon isotope data-set related to coralline sponges in the Caribbean Sea. The original interpretation led to the discrimination between a pre-industrial period, with a signal controlled by solar-induced climatic variations, followed by the industrial era, characterized by a progressive δ(13)C negative shift due to the massive anthropogenic carbon emissions. Our re-analysis allowed to extract from the raw isotopic data evidence of a solar forcing still visible during the industrial era, with a particular reference to the 88-year Gleissberg periods. These signals are related to slope changes in both the δ(13)C versus time and the δ(13)C versus carbon emission curves.

  18. Transmembrane exchange of hyperpolarized 13C-urea in human erythrocytes: subminute timescale kinetic analysis.

    PubMed

    Pagès, Guilhem; Puckeridge, Max; Liangfeng, Guo; Tan, Yee Ling; Jacob, Chacko; Garland, Marc; Kuchel, Philip W

    2013-11-05

    The rate of exchange of urea across the membranes of human erythrocytes (red blood cells) was quantified on the 1-s to 2-min timescale. (13)C-urea was hyperpolarized and subjected to rapid dissolution and the previously reported (partial) resolution of (13)C NMR resonances from the molecules inside and outside red blood cells in suspensions was observed. This enabled a stopped-flow type of experiment to measure the (initially) zero-trans transport of urea with sequential single-pulse (13)C NMR spectra, every second for up to ~2 min. Data were analyzed using Bayesian reasoning and a Markov chain Monte Carlo method with a set of simultaneous nonlinear differential equations that described nuclear magnetic relaxation combined with transmembrane exchange. Our results contribute to quantitative understanding of urea-exchange kinetics in the whole body; and the methodological approach is likely to be applicable to other cellular systems and tissues in vivo.

  19. GFT projection NMR for efficient (1)H/ (13)C sugar spin system identification in nucleic acids.

    PubMed

    Atreya, Hanudatta S; Sathyamoorthy, Bharathwaj; Jaipuria, Garima; Beaumont, Victor; Varani, Gabriele; Szyperski, Thomas

    2012-12-01

    A newly implemented G-matrix Fourier transform (GFT) (4,3)D HC(C)CH experiment is presented in conjunction with (4,3)D HCCH to efficiently identify (1)H/(13)C sugar spin systems in (13)C labeled nucleic acids. This experiment enables rapid collection of highly resolved relay 4D HC(C)CH spectral information, that is, shift correlations of (13)C-(1)H groups separated by two carbon bonds. For RNA, (4,3)D HC(C)CH takes advantage of the comparably favorable 1'- and 3'-CH signal dispersion for complete spin system identification including 5'-CH. The (4,3)D HC(C)CH/HCCH based strategy is exemplified for the 30-nucleotide 3'-untranslated region of the pre-mRNA of human U1A protein.

  20. Magnetic susceptibility effects on 13C MAS NMR spectra of carbon materials and graphite.

    PubMed

    Freita, J C; Emmerich, F G; Cernicchiaro, G R; Sampaio, L C; Bonagamba, T J

    2001-01-01

    13C high-resolution solid-state nuclear magnetic resonance (NMR) was employed to study carbon materials prepared through the thermal decomposition of four different organic precursors (rice hulls, endocarp of babassu coconut, peat, and PVC). For heat treatment temperatures (HTTs) above about 600 C, all materials presented 13C NMR spectra composed of a unique resonance line associated with carbon atoms in aromatic planes. With increasing HTT a continuous broadening of this resonance and a diamagnetic shift in its central frequency were verified for all samples. The evolution of the magnitude and anisotropy of the magnetic susceptibility of the heat-treated carbon samples with HTT explains well these findings. It is shown that these results are better understood when a comparison is made with the features of the 13C NMR spectrum of polycrystalline graphite, for which the magnetic susceptibility effect is also present and is much more pronounced.

  1. δ13C in aspen tree-rings using a long-term soil moisture record

    NASA Astrophysics Data System (ADS)

    Dymond, S.; Roden, J. S.; Bolstad, P.; Kolka, R. K.

    2013-12-01

    Isotopes have been used to assess the relationship between δ13C and climate variables such as precipitation, temperature, and PDSI. However, soil moisture, which gives a much better indication of the water available to the tree as well as its evaporative process, has either been ignored or has been modeled. At the Marcell Experimental Forest (MEF), scientists have collected 50 years of uniform, depth- resolved, seasonal, and spatially replicated soil moisture in addition to climate measurements (e.g. precipitation and temperature) and stream discharge. We utilized this unique soil moisture dataset to evaluate whether δ13C preserved annually in aspen tree-rings can be used as an indicator of past soil water availability. We found inter-annual variation between individual trees that was consistent with soil moisture availability, suggesting that δ13C can be successfully used to understand water-plant dynamics in aspen trees.

  2. *d13C composition of primary producers and role of detritus in a freshwater coastal ecosystem

    USGS Publications Warehouse

    Keough, J.R.; Hagley, C.A.; Sierszen, M.

    1998-01-01

    Stable-isotope ratio signatures of primary producers in a coastal wetland and in adjacent offshore waters of western Lake Superior indicated that phytoplankton are the primary source of carbon for the grazing food web of this ecosystem. This study outlines the possible roles of other autotrophs in this regard. Isotopic signatures of macrophytes reflected their life-form-associated constraints on diffusion of inorganic carbon. Data indicated that differences between wetland and lake phytoplankton may be explained by the isotopic signatures of their dissolved inorganic carbon (DIC) sources. Results of an in situ experiment showed that respiration associated with macrophyte decomposition is capable of enriching surrounding water with significant amounts of *d13C-depleted DIC and lowering the net *d13C ratio of DIC in water in low-turbulence situations. The *d13C ratio for wetland phytoplankton may be depleted relative to pelagic algae because the fixed carbon is derived from decomposing detritus.

  3. Probing crystal packing of uniformly (13)C-enriched powder samples using homonuclear dipolar coupling measurements.

    PubMed

    Mollica, Giulia; Dekhil, Myriam; Ziarelli, Fabio; Thureau, Pierre; Viel, Stéphane

    2015-02-01

    The relationship between the crystal packing of powder samples and long-range (13)C-(13)C homonuclear dipolar couplings is presented and illustrated for the case of uniformly (13)C-enriched L-alanine and L-histidine·HCl·H2O. Dipolar coupling measurement is based on the partial reintroduction of dipolar interactions by spinning the sample slightly off-magic-angle, while the coupling of interest for a given spin pair is isolated with a frequency-selective pulse. A cost function is used to correlate the so-derived dipolar couplings to trial crystal structures of the samples under study. This procedure allowed for the investigation of the l-alanine space group and L-histidine·HCl·H2O space group and unit-cell parameters.

  4. δ 13C response surface resolves humidity and temperature signals in trees

    NASA Astrophysics Data System (ADS)

    Edwards, T. W. D.; Graf, W.; Trimborn, P.; Stichler, W.; Lipp, J.; Payer, H. D.

    2000-01-01

    Stem cellulose of bean plants ( Vicia faba) grown under controlled conditions exhibits inverse linear carbon-isotope reactions to changes in both relative humidity (RH) and temperature (T), readily mappable as a planar δ 13C response surface in RH-T space. The analogous response surface for annual late-wood cellulose δ 13C from a field calibration using fir trees ( Abies alba) in the Black Forest, southern Germany, also supports resolution of independent δ-RH and δ-T effects. The response of cellulose δ 13C to RH and T derived from this new calibration differs markedly from estimates based on univariate linear regression analysis: The sensitivity of δ 13C to RH is stronger than that inferred previously ( c. -0.17‰/% vs. -0.12‰/%, respectively), whereas the δ-T coefficient is weaker and reversed in sign ( c. -0.15‰/K vs. +0.36‰/K). This new perspective on the coupled influence of moisture and temperature changes on tree-ring cellulose δ 13C helps to unify divergent observations about carbon-isotope signals in trees, especially the broad range of apparent δ-T relations obtained in calibration studies, which are often used as paleoclimate transfer functions. Although this highlights the large potential uncertainties surrounding paleoclimate reconstruction based solely on δ 13C data, coupling of the carbon-isotope response-surface approach with equivalent response surfaces for hydrogen or oxygen isotopes may afford new opportunities for investigating the nature of past climate variability and change from tree-ring sequences.

  5. Process Model for Studying Regional 13C Stable Isotope Exchange between Vegetation and Atmosphere

    NASA Astrophysics Data System (ADS)

    Chen, J. M.; Chen, B.; Huang, L.; Tans, P.; Worthy, D.; Ishizawa, M.; Chan, D.

    2007-12-01

    The variation of the stable isotope 13CO2 in the air in exchange with land ecosystems results from fractionation processes in both plants and soil during photosynthesis and respiration. Its diurnal and seasonal variations therefore contain information on the carbon cycle. We developed a model (BEPS-iso) to simulate its exchange between vegetation and the atmosphere. To be useful for regional carbon cycle studies, the model has the following characteristics: (i) it considers the turbulent mixing in the vertical profile from the soil surface to the top of the planetary boundary layer (PBL); (ii) it scales individual leaf photosynthetic discrimination to the whole canopy through the separation of sunlit and shaded leaf groups; (iii) through simulating leaf-level photosynthetic processes, it has the capacity to mechanistically examine isotope discrimination resulting from meteorological forcings, such as radiation, precipitation and humidity; and (iv) through complete modeling of radiation, energy and water fluxes, it also simulates soil moisture and temperature needed for estimating ecosystem respiration and the 13C signal from the soil. After validation using flask data acquired at 20 m level on a tower near Fraserdale, Ontario, Canada, during intensive campaigns (1998-2000), the model has been used for several purposes: (i) to investigate the diurnal and seasonal variations in the disequilibrium in 13C fractionation between ecosystem respiration and photosynthesis, which is an important step in using 13C measurements to separate these carbon cycle components; (ii) to quantify the 13C rectification in the PBL, which differs significantly from CO2 rectification because of the diurnal and seasonal disequilibriums; and (iii) to model the 13C spatial and temporal variations over the global land surface for the purpose of CO2 inversion using 13C as an additional constraint.

  6. Neuroprotective effects of caffeine in MPTP model of Parkinson's disease: A (13)C NMR study.

    PubMed

    Bagga, Puneet; Chugani, Anup N; Patel, Anant B

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of nigrostriatal dopaminergic neurons with an accompanying neuroinflammation leading to loss of dopamine in the basal ganglia. Caffeine, a well-known A2A receptor antagonist is reported to slow down the neuroinflammation caused by activated microglia and reduce the extracellular glutamate in the brain. In this study, we have evaluated the neuroprotective effect of caffeine in the MPTP model of PD by monitoring the region specific cerebral energy metabolism. Adult C57BL6 mice were treated with caffeine (30 mg/kg, i.p.) 30 min prior to MPTP (25 mg/kg, i.p.) administration for 8 days. The paw grip strength of mice was assessed in order to evaluate the motor function after various treatments. For metabolic studies, mice were infused with [1,6-(13)C2]glucose, and (13)C labeling of amino acids was monitored using ex vivo(1)H-[(13)C]-NMR spectroscopy. The paw grip strength was found to be reduced following the MPTP treatment. The caffeine pretreatment showed significant protection against the reduction of paw grip strength in MPTP treated mice. The levels of GABA and myo-inositol were found to be elevated in the striatum of MPTP treated mice. The (13)C labeling of GluC4, GABAC2 and GlnC4 from [1,6-(13)C2]glucose was decreased in the cerebral cortex, striatum, olfactory bulb, thalamus and cerebellum suggesting impaired glutamatergic and GABAergic neuronal activity and neurotransmission of the MPTP treated mice. Most interestingly, the pretreatment of caffeine maintained the (13)C labeling of amino acids to the control values in cortical, olfactory bulb and cerebellum regions while it partially retained in striatal and thalamic regions in MPTP treated mice. The pretreatment of caffeine provides a partial neuro-protection against severe striatal degeneration in the MPTP model of PD.

  7. Kinetic modeling of hyperpolarized 13C 1-pyruvate metabolism in normal rats and TRAMP mice

    NASA Astrophysics Data System (ADS)

    Zierhut, Matthew L.; Yen, Yi-Fen; Chen, Albert P.; Bok, Robert; Albers, Mark J.; Zhang, Vickie; Tropp, Jim; Park, Ilwoo; Vigneron, Daniel B.; Kurhanewicz, John; Hurd, Ralph E.; Nelson, Sarah J.

    2010-01-01

    PurposeTo investigate metabolic exchange between 13C 1-pyruvate, 13C 1-lactate, and 13C 1-alanine in pre-clinical model systems using kinetic modeling of dynamic hyperpolarized 13C spectroscopic data and to examine the relationship between fitted parameters and dose-response. Materials and methodsDynamic 13C spectroscopy data were acquired in normal rats, wild type mice, and mice with transgenic prostate tumors (TRAMP) either within a single slice or using a one-dimensional echo-planar spectroscopic imaging (1D-EPSI) encoding technique. Rate constants were estimated by fitting a set of exponential equations to the dynamic data. Variations in fitted parameters were used to determine model robustness in 15 mm slices centered on normal rat kidneys. Parameter values were used to investigate differences in metabolism between and within TRAMP and wild type mice. ResultsThe kinetic model was shown here to be robust when fitting data from a rat given similar doses. In normal rats, Michaelis-Menten kinetics were able to describe the dose-response of the fitted exchange rate constants with a 13.65% and 16.75% scaled fitting error (SFE) for kpyr→lac and kpyr→ala, respectively. In TRAMP mice, kpyr→lac increased an average of 94% after up to 23 days of disease progression, whether the mice were untreated or treated with casodex. Parameters estimated from dynamic 13C 1D-EPSI data were able to differentiate anatomical structures within both wild type and TRAMP mice. ConclusionsThe metabolic parameters estimated using this approach may be useful for in vivo monitoring of tumor progression and treatment efficacy, as well as to distinguish between various tissues based on metabolic activity.

  8. Habitat-specific differences in plasticity of foliar δ13C in temperate steppe grasses

    PubMed Central

    Liu, Yanjie; Zhang, Lirong; Niu, Haishan; Sun, Yue; Xu, Xingliang

    2014-01-01

    A decrease in foliar δ13C with increasing precipitation is a common tendency in steppe plants. However, the rate of decrease has been reported to differ between different species or populations. We here hypothesized that plant populations in the same habitat of temperate steppes may not differ in foliar δ13C response patterns to precipitation, but could differ in the levels of plasticity of foliar δ13C across different habitats. In order to test this hypothesis, we conducted controlled watering experiments in northeast China at five sites along a west–east transect at latitude 44°N, which show substantial interannual fluctuations and intra-annual changes in precipitation among them. In 2001, watering treatment (six levels, three replicates) was assigned to 18 plots at each site. The responses of foliar δ13C to precipitation (i.e., the sum of watering and rainfall) were determined in populations of several grass species that were common across all sites. Although similar linear regression slopes were observed for populations of different species growing at the same site, significantly different slopes were obtained for populations of the same species growing at different sites. Further, the slope of the line progressively decreased from Site I to Site V for all species in this study. These results suggest habitat-specific differences in plasticity of foliar δ13C in temperate steppe grasses. This indicates that species' δ13C response to precipitation is conservative at the same site due to their long-term acclimation, but the mechanism responsible behind this needs further investigations. PMID:25035804

  9. {sup 13}C-enrichment at carbons 8 and 2 of uric acid after {sup 13}C-labeled folate dose in man

    SciTech Connect

    Baggott, Joseph E.; Gorman, Gregory S.; Morgan, Sarah L.; Tamura, Tsunenobu . E-mail: tamurat@uab.edu

    2007-09-21

    To evaluate folate-dependent carbon incorporation into the purine ring, we measured {sup 13}C-enrichment independently at C{sub 2} and C{sub 8} of urinary uric acid (the final catabolite of purines) in a healthy male after an independent oral dose of [6RS]-5-[{sup 13}C]-formyltetrahydrofolate ([6RS]-5-H{sup 13}CO-H{sub 4}folate) or 10-H{sup 13}CO-7,8-dihydrofolate (10-H{sup 13}CO-H{sub 2}folate). The C{sub 2} position was {sup 13}C-enriched more than C{sub 8} after [6RS]-5-H{sup 13}CO-H{sub 4}folate, and C{sub 2} was exclusively enriched after 10-H{sup 13}CO-H{sub 2}folate. The enrichment of C{sub 2} was greater from [6RS]-5-H{sup 13}CO-H{sub 4}folate than 10-H{sup 13}CO-H{sub 2}folate using equimolar bioactive doses. Our data suggest that formyl C of [6RS]-10-H{sup 13}CO-H{sub 4}folate was not equally utilized by glycinamide ribotide transformylase (enriches C{sub 8}) and aminoimidazolecarboxamide ribotide (AICAR) transformylase (enriches C{sub 2}), and the formyl C of 10-H{sup 13}CO-H{sub 2}folate was exclusively used by AICAR transformylase. 10-HCO-H{sub 2}folate may function in vivo as the predominant substrate for AICAR transformylase in humans.

  10. 13C-NMR spectra and contact time experiment for Skjervatjern fulvic and humic acids

    USGS Publications Warehouse

    Malcolm, R.L.

    1992-01-01

    The T(CP) and T(1p) time constants for Skjervatjern fulvic and humic acids were determined to be short with T(CP) values ranging from 0.14 ms to 0.53 ms and T(1p) values ranging from 3.3 ms to 5.9 ms. T(CP) or T(1p) time constants at a contact time of 1 ms are favorable for quantification of 13C-NMR spectra. Because of the short T(CP) values, correction factors for signal intensity for various regions of the 13C-NMR spectra would be necessary at contact times greater than 1.1 ms or less than 0.9 ms. T(CP) and T(1p) values have a limited non-homogeneity within Skjervatjern fulvic and humic acids. A pulse delay or repeat time of 700 ms is more than adequate for quantification of these 13C-NMR spectra. Paramagnetic effects in these humic substances are precluded due to low inorganic ash contents, low contents of Fe, Mn, and Co, and low organic free-radical contents. The observed T(CP) values suggest that all the carbon types in Skjervatjern fulvic and humic acids are fully cross-polarized before significant proton relaxation occurs. The 13C-NMR spectra for Skjervatjern fulvic acid is similar to most aquatic fulvic acids as it is predominantly aliphatic, low in aromaticity (fa1 = 24), low in phenolic content, high in carboxyl content, and has no resolution of a methoxyl peak. The 13C-NMR spectra for Skjervatjern humic acid is also similar to most other aquatic humic acids in that it is also predominantly aliphatic, high in aromaticity (fa1 = 38), moderate in phenolic content, moderate in carboxyl content, and has a clear resolution of a methoxyl carbon region. After the consideration of the necessary 13C-NMR experimental conditions, these spectra are considered to be quantitative. With careful consideration of the previously determined 13C-NMR experimental conditions, quantitative spectra can be obtained for humic substances in the future from the HUMEX site. Possible changes in humic substances due to acidification should be determined from 13C-NMR data.

  11. Stratification of δ(13)C values of leaves in Amazonian rain forests.

    PubMed

    Medina, E; Minchin, P

    1980-01-01

    The contribution of soil respiration to the photosynthesis of the shade flora in the Amazon forest was evaluated by measuring the δ(13)C values of leaves collected at different levels in two forest communities. Canopy leaves have an average δ(13)C of-30.5‰ in the podsol forest and-28.7‰ in the laterite forest. Leaves from plants in the lower forest strata have a significantly lower value of-35.2‰ in the podsol forest and-34.3‰ in the laterite forest.

  12. Spinning sidebands from chemical shift anisotropy in 13C MAS imaging.

    PubMed

    Scheler, U; Blümich, B; Spiess, H W

    1993-07-01

    Solid state imaging by 13C MAS imaging is described. The spinning sidebands occurring at moderate spinning speeds, which disturb the images, can be suppressed by TOSS. For rigid solids the spatial resolution that can be achieved in this way is better than that of 1H images at the same spinning speed. Spatially resolved spectra with or without spinning sidebands can likewise be recorded providing information about the isotropic and the anisotropic chemical shifts which can be exploited for the study of structure, order and dynamics. The techniques are demonstrated on a phantom made with 13C-labelled glycine.

  13. 13C-methionine breath tests for mitochondrial liver function assessment.

    PubMed

    Candelli, M; Miele, L; Armuzzi, A; Nista, E C; Pignataro, G; Fini, L; Cazzato, I A; Zocco, M A; Bartolozzi, F; Gasbarrini, G; Grieco, A; Gasbarrini, A

    2008-01-01

    13C-methionine breath test has been proposed as a non-invasive tool for the assessment of human hepatic mithocondrial function. Two methionine breath labeled with 13C in differents point of his molecular structure have been used for breath test analisys. Aim of this study was to compare two differently 13C-labeled methionines in the evaluation of mitochondrial oxidation in basal conditions and after an acute oxidative stress. 15 healthy male subjects (mean age 30.5 +/- 3.1) received [methyl-13C]-methionine dissolved in water. Breath samples were taken at baseline and and 10, 20, 30, 45, 60, 75, 90, 105 and 120 minutes after the ingestion of the labeled substrate. Forthy-eight hours later, subjects underwent the same test 30 minutes after ethanol ingestion (0,3 g/kg of body weight). Seven-day later, subjects underwent breath test using (L-methionine-1-13COOH) as substrate, in basal condition and after ethanol ingestion. At basal condition, the cumulative percentage of 13CO2 recovered in breath during the test period (%cum-dose) was higher using L-methionine-1-13COOH than [methyl-13C]-methionine (10.25 +/- 1.0 vs 4.07 +/- 0.8; p < 0.01). After ethanol ingestion, % cum dose was significantly decreased at 60 and 120 minutes with both methionines (120 min: 10.25 +/- 1.0 vs 5.03% +/- 1.8; < 0.01 and 4.07 +/- 0.8 vs 2.16% +/- 0.9; p < 0.01, respectively). However, %cum-dose during L-methionine-1-13C-breath test was significantly lower than that observed during methyl-13C-methionine breath test (120 minutes: 5.03% +/- 1.8 vs 2.16% +/- 0.9; p < 0.01). In conclusion, breath test based on L-methionine-1-13COOH seems to show a greater reliability when compared to [methyl-13C]-methionine to assess mitochondrial function because a larger amount of labeled carbon that reaches the Krebs' cicle.

  14. Analysis and theoretical modeling of 18O enriched carbon dioxide spectrum by CRDS near 1.35 μm: (II) 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O

    NASA Astrophysics Data System (ADS)

    Karlovets, E. V.; Campargue, A.; Kassi, S.; Tashkun, S. A.; Perevalov, V. I.

    2017-04-01

    This contribution is the second part of the analysis of the room temperature absorption spectrum of 18O enriched carbon dioxide by very high sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm-1 (1.43-1.26 μm). Overall, more than 8600 lines belonging to 166 bands of eleven carbon dioxide isotopologues were rovibrationnally assigned. In a first part (Kassi et al. J Quant Spectrosc Radiat Transfer 187 (2017) 414-425, http://dx.doi.org/10.1016/j.jqsrt.2016.09.002), the results relative to mono-substituted isotopologues, 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2, were presented. This second contribution is devoted to the multiply-substituted isotopologues or clumped isotopologues of particular importance in geochemistry: 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O. On the basis of the predictions of effective Hamiltonian models, a total of 3195 transitions belonging to 73 bands were rovibrationnally assigned for these seven species. Among the 73 observed bands, 55 are newly reported. All the identified bands correspond to ΔP=10 and 11 series of transitions, where P= 2V1+V2+3V3 is the polyad number (Vi are vibrational quantum numbers). The accurate spectroscopic parameters of 70 bands have been determined from the standard band-by-band analysis. Global fits of the measured line intensities of the ΔP=10 series of transitions of 17O12C18O and 16O13C18O and of the ΔP=11 series of transitions of 12C18O2, 17O12C18O, 16O13C18O and 13C18O2 were performed to determine the corresponding sets of the effective dipole moment parameters.

  15. CO bands in V4334 Sgr (Sakurai's Object): The 12C/13C ratio

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.; Geballe, T. R.; Evans, A.; Smalley, B.; Eyres, S. P. S.; Tyne, V. H.; Yakovina, L. A.

    2004-04-01

    We present the results of our analysis of a high resolution (R≃30 000) infrared spectrum of V4334 Sgr (Sakurai's Object) around the first overtone CO bands, obtained in 1998 July. The 12CO and 13CO bands are well-resolved, and we compute synthetic hydrogen-deficient model atmosphere spectra to determine the 12C/13C ratio. We find 12C/13C ≃ 4 ± 1, consistent with the interpretation of V4334 Sgr as an object that has undergone a very late thermal pulse.

  16. Synthesis and NMR studies of (13)C-labeled vitamin D metabolites.

    PubMed

    Okamura, William H; Zhu, Gui-Dong; Hill, David K; Thomas, Richard J; Ringe, Kerstin; Borchardt, Daniel B; Norman, Anthony W; Mueller, Leonard J

    2002-03-08

    Isotope-labeled drug molecules may be useful for probing by NMR spectroscopy the conformation of ligand associated with biological hosts such as membranes and proteins. Triple-labeled [7,9,19-(13)C(3)]-vitamin D(3) (56), its 25-hydroxylated and 1 alpha,25-dihydroxylated metabolites (58 and 68, respectively), and other labeled materials have been synthesized via coupling of [9-(13)C]-Grundmann's ketone 39 or its protected 25-hydroxy derivative 43 with labeled A ring enyne fragments 25 or 26. The labeled CD-ring fragment 39 was prepared by a sequence involving Grignard addition of [(13)C]-methylmagnesium iodide to Grundmann's enone 28, oxidative cleavage, functional group modifications leading to seco-iodide 38, and finally a kinetic enolate S(N)2 cycloalkylation. The C-7,19 double labeling of the A-ring enyne was achieved by the Corey-Fuchs/Wittig processes on keto aldehyde 11. By employing these labeled fragments in the Wilson-Mazur route, the C-7,9,19 triple-(13)C-labeled metabolites 56, 58, and 68 as well as other (13)C-labeled metabolites have been prepared. In an initial NMR investigation of one of the labeled metabolites prepared in this study, namely [7,9,19-(13)C(3)]-25-hydroxyvitamin D(3) (58), the three (13)C-labeled carbons of the otherwise water insoluble steroid could be clearly detected by (13)C NMR analysis at 0.1 mM in a mixture of CD(3)OD/D(2)O (60/40) or in aqueous dimethylcyclodextrin solution and at 2 mM in 20 mM sodium dodecyl sulfate (SDS) aqueous micellar solution. In the SDS micellar solution, a double half-filter NOESY experiment revealed that the distance between the H(19Z) and H(7) protons is significantly shorter than that of the corresponding distance calculated from the solid state (X-ray) structure of the free ligand. The NMR data in micelles reveals that 58 exists essentially completely in the alpha-conformer with the 3 beta-hydroxyl equatorially oriented, just as in the solid state. The shortened distance (H(19Z))-H(7)) in micellar

  17. Coupling aboveground and belowground activities using short term fluctuations in 13C composition of soil respiration

    NASA Astrophysics Data System (ADS)

    Epron, D.; Parent, F.; Grossiord, C.; Plain, C.; Longdoz, B.; Granier, A.

    2011-12-01

    There is a growing amount of evidence that belowground processes in forest ecosystems are tightly coupled to aboveground activities. Soil CO2 efflux, the largest flux of CO2 to the atmosphere, is dominated by root respiration and by respiration of microorganisms that find the carbohydrates required to fulfil their energetic costs in the rhizosphere. A close coupling between aboveground photosynthetic activity and soil CO2 efflux is therefore expected. The isotopic signature of photosynthates varies with time because photosynthetic carbon isotope discrimination is dynamically controlled by environmental factors. This temporal variation of δ13C of photosynthate is thought to be transferred along the tree-soil continuum and it will be retrieved in soil CO2 efflux after a time lag that reflects the velocity of carbon transport from canopy to belowground. However, isotopic signature of soil CO2 efflux is not solely affected by photosynthetic carbon discrimination, bur also by post photosynthetic fractionation, and especially by fractionation processes affecting CO2 during the transport from soil layers to surface. Tunable diode laser spectrometry is a useful tool to quantify short-term variation in δ13C of soil CO2 efflux and of CO2 in the soil atmosphere. We set up hydrophobic tubes to measure the vertical profile of soil CO2 concentration and its δ13C composition in a temperate beech forest, and we monitored simultaneously δ13C of trunk and soil CO2 efflux, δ13C of phloem exudate and δ13C of leaf sugars. We evidenced that temporal changes in δ13C of soil CO2 and soil CO2 efflux reflected changes in environmental conditions that affect photosynthetic discrimination and that soil CO2 was 4.4% enriched compared to soil CO2 efflux according to diffusion fractionation. However, this close coupling can be disrupted when advective transport of CO2 took place. We also reported evidences that temporal variations in the isotopic composition of soil CO2 efflux reflect

  18. Origin of acetaldehyde during milk fermentation using (13)C-labeled precursors.

    PubMed

    Ott, A; Germond, J E; Chaintreau, A

    2000-05-01

    Acetaldehyde formation by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus during fermentation of cow's milk was investigated using (13)C-labeled glucose, L-threonine, and pyruvate with a recent static-and-trapped-headspace technique that does not require derivatization of acetaldehyde prior to gas chromatography-mass spectrometry. Over 90% and almost 100% of acetaldehyde originated from glucose during fermentation by L. delbrueckii subsp. bulgaricus and S. thermophilus, respectively, taking into account both singly and doubly labeled acetaldehyde. As both microorganisms showed threonine aldolase activity and formed labeled acetaldehyde from (13)C-labeled threonine during the fermentation of milk, this amino acid should also contribute to the acetaldehyde produced.

  19. Methyl [13C]glucopyranosiduronic acids: effect of COOH ionization and exocyclic structure on NMR spin-couplings.

    PubMed

    Zhang, Wenhui; Hu, Xiaosong; Carmichael, Ian; Serianni, Anthony S

    2012-11-02

    Methyl α- and β-D-glucopyranuronides singly labeled with (13)C at C1-C6 were prepared from the corresponding (13)C-labeled methyl D-glucopyranosides, and multiple NMR J-couplings (J(HH), J(CH), and J(CC)) were measured in their protonated and ionized forms in aqueous ((2)H(2)O) solution. Solvated density functional theory (DFT) calculations of J-couplings in structurally related model compounds were performed to determine how well the calculated J-couplings matched the experimental values in saccharides bearing an ionizable substituent. Intraring J(HH) values in both uronide anomers, including (3)J(H4,H5), are unaffected by solution pD, and COOH ionization exerts little effect on J(CH) and J(CC) except for (1)J(C1,H1), (1)J(C4,H4), (1)J(C5,H5), (1)J(C5,C6), and (2)J(C3,C5), where changes of up to 5 Hz were observed. Some of these changes are associated with changes in bond lengths upon ionization; in general, better agreement between theory and experiment was observed for couplings less sensitive to exocyclic C-O bond conformation. Titration of (1)H and (13)C chemical shifts, and some J-couplings, yielded a COOH pK(a) of 3.0 ± 0.1 in both anomers. DFT calculations suggest that substituents proximal to the exocyclic COOH group (i.e., the C4-O4 bond) influence the activation barrier to C5-C6 bond rotation due to transient intramolecular H-bonding. A comparison of J-couplings in the glucopyranuronides to corresponding J-couplings in the glucopyranosides showed that more pervasive changes occur upon conversion from a COOH to a CH(2)OH substituent at C6 than from COOH ionization within the uronides. Twelve J-couplings are affected, with the largest being (1)J(C5,C6) (∼18 Hz larger in the uronides), followed by (2)J(C6,H5) (∼2.5 Hz more negative in the uronides).

  20. Simultaneous steady-state and dynamic 13C NMR can differentiate alternative routes of pyruvate metabolism in living cancer cells.

    PubMed

    Yang, Chendong; Harrison, Crystal; Jin, Eunsook S; Chuang, David T; Sherry, A Dean; Malloy, Craig R; Merritt, Matthew E; DeBerardinis, Ralph J

    2014-02-28

    Metabolic reprogramming facilitates cancer cell growth, so quantitative metabolic flux measurements could produce useful biomarkers. However, current methods to analyze flux in vivo provide either a steady-state overview of relative activities (infusion of (13)C and analysis of extracted metabolites) or a dynamic view of a few reactions (hyperpolarized (13)C spectroscopy). Moreover, although hyperpolarization has successfully quantified pyruvate-lactate exchanges, its ability to assess mitochondrial pyruvate metabolism is unproven in cancer. Here, we combined (13)C hyperpolarization and isotopomer analysis to quantify multiple fates of pyruvate simultaneously. Two cancer cell lines with divergent pyruvate metabolism were incubated with thermally polarized [3-(13)C]pyruvate for several hours, then briefly exposed to hyperpolarized [1-(13)C]pyruvate during acquisition of NMR spectra using selective excitation to maximize detection of H[(13)C]O3(-) and [1-(13)C]lactate. Metabolites were then extracted and subjected to isotopomer analysis to determine relative rates of pathways involving [3-(13)C]pyruvate. Quantitation of hyperpolarized H[(13)C]O3(-) provided a single definitive metabolic rate, which was then used to convert relative rates derived from isotopomer analysis into quantitative fluxes. This revealed that H[(13)C]O3(-) appearance reflects activity of pyruvate dehydrogenase rather than pyruvate carboxylation followed by subsequent decarboxylation reactions. Glucose substantially altered [1-(13)C]pyruvate metabolism, enhancing exchanges with [1-(13)C]lactate and suppressing H[(13)C]O3(-) formation. Furthermore, inhibiting Akt, an oncogenic kinase that stimulates glycolysis, reversed these effects, indicating that metabolism of pyruvate by both LDH and pyruvate dehydrogenase is subject to the acute effects of oncogenic signaling on glycolysis. The data suggest that combining (13)C isotopomer analyses and dynamic hyperpolarized (13)C spectroscopy may enable

  1. Spatio-temporal variability of Δ13C in tree-rings of Aleppo pine

    NASA Astrophysics Data System (ADS)

    del Castillo, Jorge; Ferrio, Juan Pedro; Voltas, Jordi

    2014-05-01

    Aim: To study the spatiotemporal variability of Δ13C using a tree-ring network of Aleppo pine (Pinus halepensis Mill.) in the eastern part of the Iberian Peninsula. In this study, we tried to understand some of the environmental drivers behind changes in Δ13C as well as to decide the most optimal sites to infer paleoclimatic information using such variables. We also try to understand key physiological aspects of P. halepensis. Methods: In order to do that, we have collected biannual Δ13C time series (1950-1998) together with mean annual precipitation (MAP), tree-ring width (TRW) and remote sensing (NDVI) data, for 7 different locations along a precipitation gradient. We assessed how correlations between variables changed along that gradient. In addition to that, we have also looked at how that precipitation gradient changed along the years and thus its relationships with the Δ13C at the spatial level, giving us an idea whether changes in MAP at each site could affect the relationship between these two variables. Results: We found that a log model better explains the relationship between Δ13C and MAP and that it reaches a saturation point at values above 800 mm of MAP. Similarly, we found that, in the drier sites, correlations between Δ13C and precipitation were higher than in wetter ones. In addition, the coefficient of variation (CV) of Δ13C was a good indicator of the correlation between Δ13C and MAP. Similarly, the mean and the CV of TRW and summer NDVI were good indicators of the level of such correlation between Δ13C and MAP. On the other hand, the inter-site analysis of the data suggested that during dry years exists a stronger relationship between Δ13C and precipitation than in wet years. Discussion: Our results pointed out that the threshold for water limitation for Aleppo pine was around MAP=800 mm, an amount that might be sufficient for the tree to grow during most of the growing season without altering its water use efficiency (WUE) by closing

  2. Pre-treatment Effects on Coral Skeletal δ 13C and δ 18O

    NASA Astrophysics Data System (ADS)

    Grottoli, A. G.; Gibb, O.; Wellington, G. M.

    2003-12-01

    Pre-treatment protocols for coral skeletal stable carbon (δ 13C) and oxygen (δ 18O) isotope analyses include no treatment, bleach (NaOH), hydrogen peroxide (H2O2), or vacuum roasting prior to analysis. Such pre-treatments are used to remove organic material prior to isotopic analyses. Researchers that do not pre-treat samples argue that such treatments result in non-linear shifts in coral skeletal δ 13C and δ 18O thus increasing the analytical error in the δ 13C and δ 18O values. Vacuum roasting does cause isotopic shifts and is no longer practiced. However, both no pre-treatment and pre-treatment (with either NaOH or H2O2) coral δ 13C and δ 18O values continue to be published in the literature. In all previous studies of the effects of NaOH and H2O2 pre-treatments on coral δ 13C and δ 18O, the samples sizes were typically small and the exact time interval being sampled and compared was not specifically controlled. Here, we evaluated the effects of NaOH and H2O2 pre-treatments on coral skeletal δ 13C and δ 18O in Pavona clavus and Pavona gigantea from Panama, and Porites compressa from Hawaii. In Panama, at least five coral fragments from five different colonies of each species were stained on November 1978 and April 1979 then collected in November 1979. In Hawaii, at least five coral fragments from five different colonies at 1.7 and 7 m depths were stained on 1 September and 21 November 1996 then collected 2 March 1997. For each fragment, a bulk skeletal sample was extracted representing the entire growth interval between the two stain lines yielding at least 24 mg of material. Sampling between the stain lines ensured that all of the fragments from a given site and species were sampled over the same time interval and avoided any potential contamination from the tissue layer. Eight milligram subsamples from each fragment were subjected to 24 hours of the following treatments: NaOH, H2O2, Milli-Q filtered water (control), or no pre-treatment (control

  3. Effects of Ergot Alkaloids on Liver Function of Piglets as Evaluated by the 13C-Methacetin and 13C-α-Ketoisocaproic Acid Breath Test

    PubMed Central

    Dänicke, Sven; Diers, Sonja

    2013-01-01

    Ergot alkaloids (the sum of individual ergot alkaloids are termed as total alkaloids, TA) are produced by the fungus Claviceps purpurea, which infests cereal grains commonly used as feedstuffs. Ergot alkaloids potentially modulate microsomal and mitochondrial hepatic enzymes. Thus, the aim of the present experiment was to assess their effects on microsomal and mitochondrial liver function using the 13C-Methacetin (MC) and 13C-α-ketoisocaproic acid (KICA) breath test, respectively. Two ergot batches were mixed into piglet diets, resulting in 11 and 22 mg (Ergot 5-low and Ergot 5-high), 9 and 14 mg TA/kg (Ergot 15-low and Ergot 15-high) and compared to an ergot-free control group. Feed intake and live weight gain decreased significantly with the TA content (p < 0.001). Feeding the Ergot 5-high diet tended to decrease the 60-min-cumulative 13CO2 percentage of the dose recovery (cPDR60) by 26% and 28% in the MC and KICA breath test, respectively, compared to the control group (p = 0.065). Therefore, both microsomal and mitochondrial liver function was slightly affected by ergot alkaloids. PMID:23322130

  4. The Late Devonian Frasnian-Famennian (F/F) biotic crisis: Insights from δ13C carb, δ13C org and 87Sr / 86Sr isotopic systematics

    NASA Astrophysics Data System (ADS)

    Chen, Daizhao; Qing, Hairuo; Li, Renwei

    2005-06-01

    A severe biotic crisis occurred during the Late Devonian Frasnian-Famennian (F/F) transition (± 367 Myr). Here we present δ13C carb, δ13C org and 87Sr / 86Sr isotopic systematics, from identical samples of two sections across F/F boundary in South China, which directly demonstrate large and frequent climatic fluctuations (˜200 kyr) from warming to cooling during the F/F transition. These climate fluctuations are interpreted to have been induced initially by increased volcanic outgassing, and subsequent enhanced chemical weathering linked to the rapid expansion of vascular plants on land, which would have increased riverine delivery to oceans and primary bioproductivity, and subsequent burial of organic matter, thereby resulting in climate cooling. Such large and frequent climatic fluctuations, together with volcanic-induced increases in nutrient (e.g., biolimiting Fe), toxin (sulfide) and anoxic water supply, and subsequent enhanced riverine fluxes and microbial bloom, were likely responsible for the stepwise faunal demise of F/F biotic crisis.

  5. OpenMebius: an open source software for isotopically nonstationary 13C-based metabolic flux analysis.

    PubMed

    Kajihata, Shuichi; Furusawa, Chikara; Matsuda, Fumio; Shimizu, Hiroshi

    2014-01-01

    The in vivo measurement of metabolic flux by (13)C-based metabolic flux analysis ((13)C-MFA) provides valuable information regarding cell physiology. Bioinformatics tools have been developed to estimate metabolic flux distributions from the results of tracer isotopic labeling experiments using a (13)C-labeled carbon source. Metabolic flux is determined by nonlinear fitting of a metabolic model to the isotopic labeling enrichment of intracellular metabolites measured by mass spectrometry. Whereas (13)C-MFA is conventionally performed under isotopically constant conditions, isotopically nonstationary (13)C metabolic flux analysis (INST-(13)C-MFA) has recently been developed for flux analysis of cells with photosynthetic activity and cells at a quasi-steady metabolic state (e.g., primary cells or microorganisms under stationary phase). Here, the development of a novel open source software for INST-(13)C-MFA on the Windows platform is reported. OpenMebius (Open source software for Metabolic flux analysis) provides the function of autogenerating metabolic models for simulating isotopic labeling enrichment from a user-defined configuration worksheet. Analysis using simulated data demonstrated the applicability of OpenMebius for INST-(13)C-MFA. Confidence intervals determined by INST-(13)C-MFA were less than those determined by conventional methods, indicating the potential of INST-(13)C-MFA for precise metabolic flux analysis. OpenMebius is the open source software for the general application of INST-(13)C-MFA.

  6. Probing metabolic processes of intact soil microbial communities using position-specific 13C-labeled glucose

    NASA Astrophysics Data System (ADS)

    Fairbanks, D. E.; Hungate, B. A.; KOCH, G. W.; Schwartz, E.; Dijkstra, P.

    2012-12-01

    Soils represent one of the largest carbon pools in the terrestrial biosphere and fluxes into or out of this pool may feedback to current climate change. Understanding the mechanisms behind microbial processes regulating C cycling, microbial turnover, and soil organic matter stabilization is hindered by our lack of understanding of the details of microbial physiology in soils. Position-specific 13C labeled metabolic tracers are proposed as a new way to probe microbial community energy production, biosynthesis, C use efficiency (the proportion of substrate incorporated into microbial biomass), and enables the determination of C fluxes through the various C metabolic pathways. We determined the 13CO2 production from microbial communities within a one hour time frame by adding six isotopomers (1-13C, 2-13C, 3-13C, 4-13C, 5-13C, 6-13C) of glucose in parallel incubations using a young volcanic soil (Pinyon-juniper wood, near Sunset Crater, Flagstaff, Arizona). We compared the measured rates of position-specific 13CO2 production with modeled results based on glucose (1-13C and U-13C) and pyruvate (1-13C and 2,3-13C) incubations. These labeling and modeling techniques may improve our ability to analyze the biochemistry and ecophysiology of intact soil microbial communities.

  7. Imazalil-cyclomaltoheptaose (beta-cyclodextrin) inclusion complex: preparation by supercritical carbon dioxide and 13C CPMAS and 1H NMR characterization.

    PubMed

    Lai, Simona; Locci, Emanuela; Piras, Alessandra; Porcedda, Silvia; Lai, Adolfo; Marongiu, Bruno

    2003-10-10

    An inclusion complex between imazalil (IMZ), a selected fungicide, and cyclomaltoheptaose (beta-cyclodextrin, betaCD) was obtained using supercritical fluid carbon dioxide. The best preparation conditions were determined, and the inclusion complex was investigated by means of 1H NMR spectroscopy in aqueous solution and 13C CPMAS NMR spectroscopy in the solid state. Information on the geometry of the betaCD/IMZ complex was obtained from ROESY spectroscopy, while the dynamics of the inclusion complex in the kilohertz range was obtained from the proton spin-lattice relaxation times in the rotating frame, T(1rho) (1H).

  8. High-resolution study of 13C16O A-X(v' = 0-9) bands using the VUV-FTS at SOLEIL: revised term values.

    PubMed

    Gavilan, Lisseth; Lemaire, Jean Louis; Eidelsberg, Michèle; Federman, S R; Stark, Glenn; Heays, Alan N; Fillion, Jean-Hugues; Lyons, James R; de Oliveira, Nelson

    2013-10-03

    We present high-resolution absorption spectral measurements of the A(1)Π-X(1)Σ(+) band system of (13)C(16)O. These were recorded with the VUV Fourier transform spectrometer (VUV-FTS) installed on the DESIRS beamline at the SOLEIL synchrotron. This work includes revised term values that extend to higher J' values than previous measurements for most v' levels and lower J' values for v' = 0. We confirm previously observed perturbations of the rotational levels in greater detail and present evidence for new perturbations. The accuracy in the wavelength determination and term values is on average within 0.01 cm(-1), improving upon previous measurements.

  9. Methylation patterns of aquatic humic substances determined by 13C NMR spectroscopy

    USGS Publications Warehouse

    Thorn, K.A.; Steelink, C.; Wershaw, R. L.

    1987-01-01

    13C NMR spectroscopy is used to examine the hydroxyl group functionality of a series of humic and fulvic acids from different aquatic environments. Samples first are methylated with 13C-labeled diazomethane. The NMR spectra of the diazomethylated samples allow one to distinguish between methyl esters of carboxylic acids, methyl ethers of phenolic hydroxyls, and methyl ethers of phenolic hydroxyls adjacent to two substituents. Samples are then permethylated with 13C-labeled methyl iodide/NaH. 13C NMR spectra of permethylated samples show that a significant fraction of the hydroxyl groups is not methylated with diazomethane alone. In these spectra methyl ethers of carbohydrate and aliphatic hydroxyls overlap with methyl ethers of phenolic hydroxyls. Side reactions of the methyltion procedure including carbon methylation in the CH3I/NaH procedure, are also examined. Humic and fulvic acids from bog, swamp, groundwater, and lake waters showssome differences in their distribution of hydroxyl groups, mainly in the concentrations of phenolic hydroxyls, which may be attributed to their different biogeochemical origins. ?? 1987.

  10. Mapping carbon fate during bleaching in a model cnidarian symbiosis: the application of (13) C metabolomics.

    PubMed

    Hillyer, Katie E; Dias, Daniel A; Lutz, Adrian; Roessner, Ute; Davy, Simon K

    2017-03-08

    Coral bleaching is a major threat to the persistence of coral reefs. Yet we lack detailed knowledge of the metabolic interactions that determine symbiosis function and bleaching-induced change. We mapped autotrophic carbon fate within the free metabolite pools of both partners of a model cnidarian-dinoflagellate symbiosis (Aiptasia-Symbiodinium) during exposure to thermal stress via the stable isotope tracer ((13) C bicarbonate), coupled to GC-MS. Symbiont photodamage and pronounced bleaching coincided with substantial increases in the turnover of non(13) C-labelled pools in the dinoflagellate (lipid and starch store catabolism). However, (13) C enrichment of multiple compounds associated with ongoing carbon fixation and de novo biosynthesis pathways was maintained (glucose, fatty acid and lipogenesis intermediates). Minimal change was also observed in host pools of (13) C-enriched glucose (a major symbiont-derived mobile product). However, host pathways downstream showed altered carbon fate and/or pool composition, with accumulation of compatible solutes and nonenzymic antioxidant precursors. In hospite symbionts continue to provide mobile products to the host, but at a significant cost to themselves, necessitating the mobilization of energy stores. These data highlight the need to further elucidate the role of metabolic interactions between symbiotic partners, during the process of thermal acclimation and coral bleaching.

  11. Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Nixon, C. A.; Romani, P. N.; Bjoraker, G. L.; Sada, P. V.; Lunsford, A. W.; Boyle, R. J.; Hesman, B. E.; McCabe, G. H.

    2009-01-01

    As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.

  12. First airborne samples of a volcanic plume for δ13C of CO2 determinations

    NASA Astrophysics Data System (ADS)

    Fischer, Tobias P.; Lopez, Taryn M.

    2016-04-01

    Volcanic degassing is one of the main natural sources of CO2 to the atmosphere. Carbon isotopes of volcanic gases enable the determination of CO2 sources including mantle, organic or carbonate sediments, and atmosphere. Until recently, this work required sample collection from vents followed by laboratory analyses. Isotope ratio infrared analyzers now enable rapid analyses of plume δ13C-CO2, in situ and in real time. Here we report the first analyses of δ13C-CO2 from airborne samples. These data combined with plume samples from the vent area enable extrapolation to the volcanic source δ13C. We performed our experiment at the previously unsampled and remote Kanaga Volcano in the Western Aleutians. We find a δ13C source composition of -4.4‰, suggesting that CO2 from Kanaga is primarily sourced from the upper mantle with minimal contributions from subducted components. Our method is widely applicable to volcanoes where remote location or activity level precludes sampling using traditional methods.

  13. Computer-assisted structural analysis of regular glycopolymers on the basis of 13C NMR data.

    PubMed

    Toukach, F V; Shashkov, A S

    2001-09-28

    A computer-assisted approach to the prediction of the primary structures of regular glycopolymers is described. The analysis is based on comparing the calculated 13C NMR spectra of all the possible structures of the repeating unit (for the given monomeric composition) to an experimental 13C NMR spectrum. The spectra generation is based on the spectral database containing information on the 13C chemical shifts of monomers, di- and trimeric fragments. If the required data are missing from this database, the special database for average glycosylation effects is used. The analysis reveals those structures with the calculated 13C NMR spectrum most close to observed. The structures of repeating units of any topology containing up to six residues linked by glycosidic, amidic or phospho-diester bridges can be predicted. Unambiguous selection of the proper structure from the output list of possible structures may require additional experimental data. Testing the created program and databases on bacterial polysaccharides and their derivatives containing up to three non-sugar residues (alditols, amino acids, phosphate groups etc.) per repeating unit revealed the good convergence of prediction with independently obtained structural data.

  14. (13)C-Labeling the carbon-fixation pathway of a highly efficient artificial photosynthetic system.

    PubMed

    Liu, Chong; Nangle, Shannon N; Colón, Brendan C; Silver, Pamela A; Nocera, Daniel G

    2017-03-15

    Interfacing the CO2-fixing microorganism, Ralstonia eutropha, to the energy derived from hydrogen produced by water splitting is a viable approach to achieving renewable CO2 reduction at high efficiencies. We employ (13)C-labeling to report on the nature of CO2 reduction in the inorganic water splitting|R. eutropha hybrid system. Accumulated biomass in a reactor under a (13)C-enriched CO2 atmosphere may be sampled at different time points during CO2 reduction. Converting the sampled biomass into gaseous CO2 allows the (13)C/(12)C ratio to be determined by gas chromatography-mass spectrometry. After 2 hours of inoculation and the initiation of water splitting, the microbes adapted and began to convert CO2 into biomass. The observed time evolution of the (13)C/(12)C ratio in accumulated biomass is consistent with a Monod model for carbon fixation. Carbon dioxide produced by catabolism was found to be minimal. This rapid response of the bacteria to a hydrogen input and to subsequent CO2 reduction at high efficiency are beneficial to achieving artificial photosynthesis for the storage of renewable energy.

  15. Determination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710

    USGS Publications Warehouse

    Singleton, Glenda L.; Revesz, Kinga; Coplen, Tyler B.

    2012-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1710 is to present a method to determine the δ13C of dissolved inorganic carbon (DIC) of water. The DIC of water is precipitated using ammoniacal strontium chloride (SrCl2) solution to form strontium carbonate (SrCO3). The δ13C is analyzed by reacting SrCO3 with 100-percent phosphoric acid (H3PO4) to liberate carbon quantitatively as carbon dioxide (CO2), which is collected, purified by vacuum sublimation, and analyzed by dual inlet isotope-ratio mass spectrometry (DI-IRMS). The DI-IRMS is a DuPont double-focusing mass spectrometer. One ion beam passes through a slit in a forward collector and is collected in the rear collector. The other measurable ion beams are collected in the front collector. By changing the ion-accelerating voltage under computer control, the instrument is capable of measuring mass/charge (m/z) 45 or 46 in the rear collector and m/z 44 and 46 or 44 and 45, respectively, in the front collector. The ion beams from these m/z values are as follows: m/z 44 = CO2 = 12C16O16O, m/z 45 = CO2 = 13C16O16O primarily, and m/z 46 = CO2 = 12C16O18O primarily. The data acquisition and control software calculates δ13C values.

  16. The 13C Neutron Source and s-Processing in AGB Stars

    NASA Astrophysics Data System (ADS)

    Trippella, Oscar; Busso, Maurizio; Palmerini, Sara; La Cognata, Marco

    The main component of the s-process accounts for about 50% of elements heavier than Kr, through n-captures occurring in asymptotic giant branch (AGB) stars, where the 13C(α, n)16O reaction is the main neutron source. Its activation below the convective envelope at third dredge-up (TDU) and its efficiency are still matters of debate, as: (i) the astrophysical factor is affected by a broad resonance near the reaction threshold and (ii) mixing mechanisms to locally produce 13C were so far mimicked mainly parametrically. We discuss both problems and, in particular, we adopt one of the recent model proposed for producing 13C and based on an exact multi-D analytical solution of MHD equations, where magnetic buoyancy induces partial mixing at the envelope border. The resulting distribution of 13C is used, together with our upgraded prescription for the reaction rate, to reproduce solar abundances through AGB models. It can account for the chemical evolution of s-elements and for the s/(C/O) ratios in low-metallicity post-AGB stars.

  17. 13C Tracking after 13CO2 Supply Revealed Diurnal Patterns of Wood Formation in Aspen.

    PubMed

    Mahboubi, Amir; Linden, Pernilla; Hedenström, Mattias; Moritz, Thomas; Niittylä, Totte

    2015-06-01

    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 (13)CO2 labeling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula × tremuloides). Tracking of (13)C 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 (13)C incorporation to lignin and cell wall carbohydrates. No (13)C 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 (13)C labeling method for the analysis of wood formation and secondary growth in trees.

  18. Optimal tracers for parallel labeling experiments and (13)C metabolic flux analysis: A new precision and synergy scoring system.

    PubMed

    Crown, Scott B; Long, Christopher P; Antoniewicz, Maciek R

    2016-11-01

    (13)C-Metabolic flux analysis ((13)C-MFA) is a widely used approach in metabolic engineering for quantifying intracellular metabolic fluxes. The precision of fluxes determined by (13)C-MFA depends largely on the choice of isotopic tracers and the specific set of labeling measurements. A recent advance in the field is the use of parallel labeling experiments for improved flux precision and accuracy. However, as of today, no systemic methods exist for identifying optimal tracers for parallel labeling experiments. In this contribution, we have addressed this problem by introducing a new scoring system and evaluating thousands of different isotopic tracer schemes. Based on this extensive analysis we have identified optimal tracers for (13)C-MFA. The best single tracers were doubly (13)C-labeled glucose tracers, including [1,6-(13)C]glucose, [5,6-(13)C]glucose and [1,2-(13)C]glucose, which consistently produced the highest flux precision independent of the metabolic flux map (here, 100 random flux maps were evaluated). Moreover, we demonstrate that pure glucose tracers perform better overall than mixtures of glucose tracers. For parallel labeling experiments the optimal isotopic tracers were [1,6-(13)C]glucose and [1,2-(13)C]glucose. Combined analysis of [1,6-(13)C]glucose and [1,2-(13)C]glucose labeling data improved the flux precision score by nearly 20-fold compared to widely use tracer mixture 80% [1-(13)C]glucose +20% [U-(13)C]glucose.

  19. Control of Mercury Accumulation And Mobility in a Forest Soil as Indicated by δ13C

    NASA Astrophysics Data System (ADS)

    Bajracharya, U.; Jackson, B.; Feng, X.

    2015-12-01

    Mobility and cycling of mercury (Hg) in soils is important. Hg leaching results in its transport to wetlands, where Hg methylates and bioaccumulates through aquatic food webs. It has been shown that Hg cycle in soil is controlled by organic matter (OM) quantity as well as quality. The latter is indicated by increase of Hg/C ratio as C/N decreases by decomposition. Here we investigate the Hg-C relationship in a temperate forest soil in Hanover, NH, with a focus of examining the control of OM quality on soil Hg accumulation and mobility. We use δ13C as an indicator of carbon quality. The soil samples from A, B and C horizons were separated into six particle size fractionations from <25 µm to 1 mm. Both the bulk soil and particle size separates were analyzed for Hg concentrations, carbon content (C%), δ13C, and Hg partition coefficient (Kd =mg gSoil-1/mg Lsolution-1). We found that the bulk Hg concentration decreases significantly with increasing δ13C (R2=0.90, p <0.0001), but Hg/C increases with δ13C (R2=0.59, p =0.009). Both Hg/C and δ13C increase with soil depth, and at a given horizon, they both increase with decreasing particle size. These results indicate that high Hg/C ratios are associated with aged, decomposed, and low quality OM. Mostly likely, this accumulation of Hg in older OM is a result of retention of Hg upon carbon loss during soil respiration. However, the relationship between particle size and Hg/C is significantly different among different horizons; the most prominent relationship occurs at the deepest C horizon. This cross effect of horizon and particle size cannot be explained by normal aging of the OM through decomposition, pointing to mechanisms of changing in Hg bonding characteristics with OM aging or particle aggregation. The measured Kd value decreased with increasing δ13C (R2=0.43, p =0.0031), indicating that Hg associated with older OM is more subject to leaching compared to younger, fresher OM. This association can also be

  20. Vertical δ13C and δ15N changes during pedogenesis

    NASA Astrophysics Data System (ADS)

    Brunn, Melanie; Spielvogel, Sandra; Wells, Andrew; Condron, Leo; Oelmann, Yvonne

    2015-04-01

    The natural abundance of soil organic matter (SOM) stable C and N isotope ratios are subjected to vertical changes throughout the soil profile. This vertical distribution is a widely reported phenomenon across varieties of ecosystems and constitutes important insights of soil carbon cycling. In most ecosystems, SOM becomes enriched in heavy isotopes by several per mill in the first few centimeters of the topsoil. The enrichment of 13C in SOM with soil depth is attributed to biological and physical-chemical processes in soil e.g., plant physiological impacts, microbial decomposition, sorption and transport processes. Such vertical trends in 13C and 15N abundance have rarely been related to SOM composition during pedogenesis. The aims of our study were to investigate short and long-term δ13C and δ15N depth changes and their interrelations under progressing pedogenesis and ecosystem development. We sampled soils across the well studied fordune progradation Haast-chronosequence, a dune ridge system under super-humid climate at the West Coast of New Zealand's South Island (43° 53' S, 169° 3' E). Soils from 11 sites with five replicates each covered a time span of around 2870 yr of soil development (from Arenosol to Podzol). Vertical changes of δ13C and δ15N values of SOM were investigated in the organic layers and in 1-cm depth intervals of the upper 10 cm of the mineral soil. With increasing soil depth SOM became enriched in δ13C by 1.9 ± SE 0.1 o and in δ15N by 6.0 ± 0.4 ‰˙Litter δ13C values slightly decreased with increasing soil age (r = -0.61; p = 0.00) likely due to less efficient assimilation linked to nutrient limitations. Fractionation processes during mycorrhizal transfer appeared to affect δ15N values in the litter. We found a strong decrease of δ15N in the early succession stages ≤ 300 yr B.P. (r = -0.95; p = 0.00). Positive relations of vertical 13C and 15N enrichment with soil age might be related to decomposition and appeared to be

  1. Turnover of microbial groups and cell components in soil: 13C analysis of cellular biomarkers

    NASA Astrophysics Data System (ADS)

    Gunina, Anna; Dippold, Michaela; Glaser, Bruno; Kuzyakov, Yakov

    2017-01-01

    Microorganisms regulate the carbon (C) cycle in soil, controlling the utilization and recycling of organic substances. To reveal the contribution of particular microbial groups to C utilization and turnover within the microbial cells, the fate of 13C-labelled glucose was studied under field conditions. Glucose-derived 13C was traced in cytosol, amino sugars and phospholipid fatty acid (PLFA) pools at intervals of 3, 10 and 50 days after glucose addition into the soil. 13C enrichment in PLFAs ( ˜ 1.5 % of PLFA C at day 3) was an order of magnitude greater than in cytosol, showing the importance of cell membranes for initial C utilization. The 13C enrichment in amino sugars of living microorganisms at day 3 accounted for 0.57 % of total C pool; as a result, we infer that the replacement of C in cell wall components is 3 times slower than that of cell membranes. The C turnover time in the cytosol (150 days) was 3 times longer than in PLFAs (47 days). Consequently, even though the cytosol pool has the fastest processing rates compared to other cellular compartments, intensive recycling of components here leads to a long C turnover time. Both PLFA and amino-sugar profiles indicated that bacteria dominated in glucose utilization. 13C enrichment decreased with time for bacterial cell membrane components, but it remained constant or even increased for filamentous microorganisms. 13C enrichment of muramic acid was the 3.5 times greater than for galactosamine, showing a more rapid turnover of bacterial cell wall components compared to fungal. Thus, bacteria utilize a greater proportion of low-molecular-weight organic substances, whereas filamentous microorganisms are responsible for further C transformations. Thus, tracing 13C in cellular compounds with contrasting turnover rates elucidated the role of microbial groups and their cellular compartments in C utilization and recycling in soil. The results also reflect that microbial C turnover is not restricted to the death or

  2. Coral 13C/12C records of vertical seafloor displacement during megathrust earthquakes west of Sumatra

    NASA Astrophysics Data System (ADS)

    Gagan, Michael K.; Sosdian, Sindia M.; Scott-Gagan, Heather; Sieh, Kerry; Hantoro, Wahyoe S.; Natawidjaja, Danny H.; Briggs, Richard W.; Suwargadi, Bambang W.; Rifai, Hamdi

    2015-12-01

    The recent surge of megathrust earthquakes and tsunami disasters has highlighted the need for a comprehensive understanding of earthquake cycles along convergent plate boundaries. Space geodesy has been used to document recent crustal deformation patterns with unprecedented precision, however the production of long paleogeodetic records of vertical seafloor motion is still a major challenge. Here we show that carbon isotope ratios (δ13C) in the skeletons of massive Porites corals from west Sumatra record abrupt changes in light exposure resulting from coseismic seafloor displacements. Validation of the method is based on the coral δ13C response to uplift (and subsidence) produced by the March 2005 Mw 8.6 Nias-Simeulue earthquake, and uplift further south around Sipora Island during a M ∼ 8.4 megathrust earthquake in February 1797. At Nias, the average step-change in coral δ13C was 0.6 ± 0.1 ‰ /m for coseismic displacements of +1.8 m and -0.4 m in 2005. At Sipora, a distinct change in Porites microatoll growth morphology marks coseismic uplift of 0.7 m in 1797. In this shallow water setting, with a steep light attenuation gradient, the step-change in microatoll δ13C is 2.3 ‰ /m, nearly four times greater than for the Nias Porites. Considering the natural variability in coral skeletal δ13C, we show that the lower detection limit of the method is around 0.2 m of vertical seafloor motion. Analysis of vertical displacement for well-documented earthquakes suggests this sensitivity equates to shallow events exceeding Mw ∼ 7.2 in central megathrust and back-arc thrust fault settings. Our findings indicate that the coral 13C /12C paleogeodesy technique could be applied to convergent tectonic margins throughout the tropical western Pacific and eastern Indian oceans, which host prolific coral reefs, and some of the world's greatest earthquake catastrophes. While our focus here is the link between coral δ13C, light exposure and coseismic crustal deformation, the

  3. Millimeter-Wave Observations of Circumstellar 14N/15N and 12C/13C Ratios: New Insights into J-Type Stars

    NASA Astrophysics Data System (ADS)

    Adande, Gilles; Ziurys, Lucy M.; Woolf, Neville

    2016-06-01

    Measurements of 14N/15N and 12C/13C isotopic ratios have been conducted towards circumstellar envelopes of a sample of evolved stars using the J = 3→2 rotational transitions of the isotopologues of HCN, observed with the Submillimeter Telescope (SMT) of the Arizona Radio Observatory (ARO). Towards the J-type stars Y CVn and RY Dra, where 12C/13C ~ 3, the 14N/15N ratios were found to be 120-180 and 225, respectively. The 14N/15N ratio is thus anomalously low relative to interstellar values and a factor ~100 lower than equilibrium values predicted from the CNO cycle. Combining these results with previous chemical and isotopic prior observations of these stars, we conclude that two anomalous behaviors are likely to have occurred in Y CVn and RY Dra. First, the stellar envelope failed to participate in the normal mixing seen in low mass red giants, in which C and then O are substantially converted to N. Secondly, both the carbon enrichment and anomalous isotopic composition of both 13C and15N could have been caused by a plume of hot gas, hydrogen poor but enriched in 12C, from a helium flash mixing into the envelope.

  4. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    PubMed

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

  5. Microbial metabolism in soil at low temperatures: Mechanisms unraveled by position-specific 13C labeling

    NASA Astrophysics Data System (ADS)

    Bore, Ezekiel

    2016-04-01

    Microbial transformation of organic substances in soil is the most important process of the C cycle. Most of the current studies base their information about transformation of organic substances on incubation studies under laboratory conditions and thus, we have a profound knowledge on SOM transformations at ambient temperatures. However, metabolic pathway activities at low temperature are not well understood, despite the fact that the processes are relevant for many soils globally and seasonally. To analyze microbial metabolism at low soil temperatures, isotopomeres of position-specifically 13C labeled glucose were incubated at three temperature; 5, -5 -20 oC. Soils were sampled after 1, 3 and 10 days and additionally after 30 days for samples at -20 °C. The 13C from individual molecule position was quantifed in respired CO2, bulk soil, extractable organic C and extractable microbial biomass by chloroform fumigation extraction (CFE) and cell membranes of microbial communities classified by 13C phospholipid fatty acid (PLFA) analysis. 13CO2 released showed a dominance of the flux from C-1 position at 5 °C. Consequently, at 5 °C, pentose phosphate pathway activity is a dominant metabolic pathway of glucose metabolization. In contrast to -5 °C and -20 oC, metabolic behaviors completely switched towards a preferential respiration of the glucose C-4 position. With decreasing temperature, microorganism strongly shifted towards metabolization of glucose via glycolysis which indicates a switch to cellular maintenance. High recoveries of 13C in extractable microbial biomass at -5 °C indicates optimal growth condition for the microorganisms. PLFA analysis showed high incorporation of 13C into Gram negative bacteria at 5 °C but decreased with temperature. Gram positive bacteria out-competed Gram negatives with decreasing temperature. This study revealed a remarkable microbial activity at temperatures below 0 °C, differing significantly from that at ambient

  6. A 13C mass isotopomer study of anaplerotic pyruvate carboxylation in perfused rat hearts.

    PubMed

    Comte, B; Vincent, G; Bouchard, B; Jetté, M; Cordeau, S; Rosiers, C D

    1997-10-17

    Anaplerotic pyruvate carboxylation was examined in hearts perfused with physiological concentrations of glucose, [U-13C3]lactate, and [U-13C3]pyruvate. Also, a fatty acid, [1-13C]octanoate, or ketone bodies were added at concentrations providing acetyl-CoA at a rate resulting in either low or substantial pyruvate decarboxylation. Relative contributions of pyruvate and fatty acids to citrate synthesis were determined from the 13C labeling pattern of effluent citrate by gas chromatography-mass spectrometry (see companion article, Comte, B., Vincent, G., Bouchard, B., and Des Rosiers, C. (1997) J. Biol. Chem. 272, 26117-26124). Precision on flux measurements of anaplerotic pyruvate carboxylation depended on the mix of substrates supplied to the heart. Anaplerotic fluxes were precisely determined under conditions where acetyl-CoA was predominantly supplied by beta-oxidation, as it occurred with 0.2 or 1 mM octanoate. Then, anaplerotic pyruvate carboxylation provided 3-8% of the OAA moiety of citrate and was modulated by concentrations of lactate and pyruvate in the physiological range. Also, the contribution of pyruvate to citrate formation through carboxylation was equal to or greater than through decarboxylation. Furthermore, 13C labeling data on tissue citric acid cycle intermediates and pyruvate suggest that (i) anaplerosis occurs also at succinate and (ii) cataplerotic malate decarboxylation is low. Rather, the presence of citrate in the effluent perfusate of hearts perfused with physiological concentrations of glucose, lactate, and pyruvate and concentrations of octanoate leading to maximal oxidative rates suggests a cataplerotic citrate efflux from mitochondria to cytosol. Taken altogether, our data raise the possibility of a link between pyruvate carboxylation and mitochondrial citrate efflux. In view of the proposed feedback regulation of glycolysis by cytosolic citrate, such a link would support a role of anaplerosis and cataplerosis in metabolic signal

  7. Single shot three‐dimensional pulse sequence for hyperpolarized 13C MRI

    PubMed Central

    Wang, Jiazheng; Wright, Alan J.; Hu, De‐en; Hesketh, Richard

    2016-01-01

    Purpose Metabolic imaging with hyperpolarized 13C‐labeled cell substrates is a promising technique for imaging tissue metabolism in vivo. However, the transient nature of the hyperpolarization, and its depletion following excitation, limits the imaging time and the number of excitation pulses that can be used. We describe here a single‐shot three‐dimensional (3D) imaging sequence and demonstrate its capability to generate 13C MR images in tumor‐bearing mice injected with hyperpolarized [1‐13C]pyruvate. Methods The pulse sequence acquires a stack‐of‐spirals at two spin echoes after a single excitation pulse and encodes the kz‐dimension in an interleaved manner to enhance robustness to B0 inhomogeneity. Spectral‐spatial pulses are used to acquire dynamic 3D images from selected hyperpolarized 13C‐labeled metabolites. Results A nominal spatial/temporal resolution of 1.25 × 1.25 × 2.5 mm3 × 2 s was achieved in tumor images of hyperpolarized [1‐13C]pyruvate and [1‐13C]lactate acquired in vivo. Higher resolution in the z‐direction, with a different k‐space trajectory, was demonstrated in measurements on a thermally polarized [1‐13C]lactate phantom. Conclusion The pulse sequence is capable of imaging hyperpolarized 13C‐labeled substrates at relatively high spatial and temporal resolutions and is robust to moderate system imperfections. Magn Reson Med 77:740–752, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26916384

  8. 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

  9. 13C-engineered carbon quantum dots for in vivo magnetic resonance and fluorescence dual-response.

    PubMed

    Xu, Yang; Li, Yu-Hao; Wang, Yue; Cui, Jian-Lin; Yin, Xue-Bo; He, Xi-Wen; Zhang, Yu-Kui

    2014-10-21

    (13)C-engineered carbon quantum dots ((13)C-QDs) were used as magnetic resonance (MR) and fluorescence dual-response probe. The enhanced (13)C-MR signal was observed at 171 ppm from carboxylic and carboxyl carbons in (13)C-QDs with 160-fold improvement on signal-to-noise ratio even when no hyperpolarization was applied, whereas the intrinsic fluorescence of C-QDs was still maintained. The stable MR and fluorescence dual-response was successfully used for long-term observation of zebrafish embryonic development. Cross-validation between MR and fluorescence confirmed the distribution of (13)C-QD in zebrafish. (13)C-MR provides specific information about the presence, magnitude, and progression of (13)C-QDs by defining MR intensity, whereas fluorescence reveals the location of (13)C-QDs with its high sensitivity. (13)C-MR and fluorescence was simultaneously observed within (13)C-QDs, and this work may expand the applications of isotope-engineered nanomaterials.

  10. Transfer of (13) C between paired Douglas-fir seedlings reveals plant kinship effects and uptake of exudates by ectomycorrhizas.

    PubMed

    Pickles, Brian J; Wilhelm, Roland; Asay, Amanda K; Hahn, Aria S; Simard, Suzanne W; Mohn, William W

    2017-04-01

    Processes governing the fixation, partitioning, and mineralization of carbon in soils are under increasing scrutiny as we develop a more comprehensive understanding of global carbon cycling. Here we examined fixation by Douglas-fir seedlings and transfer to associated ectomycorrhizal fungi, soil microbes, and full-sibling or nonsibling neighbouring seedlings. Stable isotope probing with 99% (13) C-CO2 was applied to trace (13) C-labelled photosynthate throughout plants, fungi, and soil microbes in an experiment designed to assess the effect of relatedness on (13) C transfer between plant pairs. The fixation and transfer of the (13) C label to plant, fungal, and soil microbial tissue was examined in biomass and phospholipid fatty acids. After a 6 d chase period, c. 26.8% of the (13) C remaining in the system was translocated below ground. Enrichment was proportionally greatest in ectomycorrhizal biomass. The presence of mesh barriers (0.5 or 35 μm) between seedlings did not restrict (13) C transfer. Fungi were the primary recipients of (13) C-labelled photosynthate throughout the system, representing 60-70% of total (13) C-enriched phospholipids. Full-sibling pairs exhibited significantly greater (13) C transfer to recipient roots in two of four Douglas-fir families, representing three- and fourfold increases (+ c. 4 μg excess (13) C) compared with nonsibling pairs. The existence of a root/mycorrhizal exudation-hyphal uptake pathway was supported.

  11. A method to trace root-respired CO2 using a 13C label

    NASA Astrophysics Data System (ADS)

    Cooperdock, S.; Breecker, D.; Litvak, M. E.

    2014-12-01

    In order to partition total soil respiration into root respiration and decomposition under ambient conditions in desert soils, the following method was developed using 13C-labeled CO2 in a modern juniper savannah in central New Mexico. The labeled CO2 was mixed with ambient air and pumped into a small (2.5 m diameter and 1.4 m tall) juniper tree canopy . 10 L of the 13CO2 was sufficient to generate a stream of air at 20 L/min for 1 hour with a CO2 concentration of 540 ppm and a δ13C value of approximately 35,000‰. Plastic tarpaulins were used as a wind block. The 13CO2 -labeled air was applied to the canopy during peak photosynthesis between 10 and 11 am on June 30 2014 during which canopy air CO2 was elevated by approximately 10 ppm over ambient and had δ13C values ranging from 50 to 1000 ‰. Over the next three days, gas and tissue samples were collected in order to trace the 13C label through the juniper tree. Leaf and root samples collected from the labeled tree and from several control trees were loaded into exetainer vials, flushed with CO2-free air and incubated in the dark for 5 hours in order to measure the carbon isotope composition of respired CO2. Samples of soil pore space gas were collected from wells under the labeled tree and a control tree and were transported to the laboratory in He-flushed exetainer vials. The δ13C values of CO2 in the soil gas samples and in the headspace of incubation vials were measured using an isotope ratio mass spectrometer. The δ13C values of foliar respiration were significantly higher than those of the control (by 3.6‰, p < 0.01) one and two days after labeling and δ13C values of root-respired CO2 were significantly higher (by 0.7‰, p = 0.01) than those of the control three days after labeling. In addition, δ13C values of soil respired CO2, determined from measurements of soil pore space CO2 at 50 cm three days after labeling, were significantly higher (by 0.7‰, p < 0.03)) for the labeled tree than control

  12. Decoupling of coral skeletal δ13C and solar irradiance over the past millennium caused by the oceanic Suess effect

    NASA Astrophysics Data System (ADS)

    Deng, Wenfeng; Chen, Xuefei; Wei, Gangjian; Zeng, Ti; Zhao, Jian-xin

    2017-02-01

    Many factors influence the seasonal changes in δ13C levels in coral skeletons; consequently, the climatic and environmental significance of such changes is complicated and controversial. However, it is widely accepted that the secular declining trend of coral δ13C over the past 200 years reflects the changes in the additional flux of anthropogenic CO2 from the atmosphere into the surface oceans. Even so, the centennial-scale variations, and their significance, of coral δ13C before the Industrial Revolution remain unclear. Based on an annually resolved coral δ13C record from the northern South China Sea, the centennial-scale variations of coral δ13C over the past millennium were studied. The coral δ13C and total solar irradiance (TSI) have a significant positive Pearson correlation and coupled variation during the Medieval Warm Period and Little Ice Age, when natural forcing controlled the climate and environment. This covariation suggests that TSI controls coral δ13C by affecting the photosynthetic activity of the endosymbiotic zooxanthellae over centennial timescales. However, there was a decoupling of the coral skeletal δ13C and TSI during the Current Warm Period, the period in which the climate and environment became linked to anthropogenic factors. Instead, coral δ13C levels have a significant Pearson correlation with both the atmospheric CO2 concentration and δ13C levels in atmospheric CO2. The correlation between coral δ13C and atmospheric CO2 suggests that the oceanic 13C Suess effect, caused by the addition of increasing amounts of anthropogenic 12CO2 to the surface ocean, has led to the decoupling of coral δ13C and TSI at the centennial scale.

  13. Multidimensional solid-state NMR studies of the structure and dynamics of pectic polysaccharides in uniformly 13C-labeled Arabidopsis primary cell walls

    SciTech Connect

    Dick-Perez, Marilu; Wang, Tuo; Salazar, Andre; Zabotina, Olga A.; Hong, Mei

    2012-07-08

    Plant cell wall (CW) polysaccharides are responsible for the mechanical strength and growth of plant cells; however, the high-resolution structure and dynamics of the CW polysaccharides are still poorly understood because of the insoluble nature of these molecules. Here, we use 2D and 3D magic-angle-spinning (MAS) solid-state NMR (SSNMR) to investigate the structural role of pectins in the plant CW. Intact and partially depectinated primary CWs of Arabidopsis thaliana were uniformly labeled with 13C and their NMR spectra were compared. Recent 13C resonance assignment of the major polysaccharides in Arabidopsis thaliana CWs allowed us to determine the effects of depectination on the intermolecular packing and dynamics of the remaining wall polysaccharides. 2D and 3D correlation spectra show the suppression of pectin signals, confirming partial pectin removal by chelating agents and sodium carbonate. Importantly, higher cross peaks are observed in 2D and 3D 13C spectra of the depectinated CW, suggesting higher rigidity and denser packing of the remaining wall polysaccharides compared with the intact CW. 13C spin–lattice relaxation times and 1H rotating-frame spin–lattice relaxation times indicate that the polysaccharides are more rigid on both the nanosecond and microsecond timescales in the depectinated CW. Taken together, these results indicate that pectic polysaccharides are highly dynamic and endow the polysaccharide network of the primary CW with mobility and flexibility, which may be important for pectin functions. This study demonstrates the capability of multidimensional SSNMR to determine the intermolecular interactions and dynamic structures of complex plant materials under near-native conditions. Copyright © 2012 John Wiley & Sons, Ltd.

  14. Isotopic variability of cave bears (δ15N, δ13C) across Europe during MIS 3

    NASA Astrophysics Data System (ADS)

    Krajcarz, Magdalena; Pacher, Martina; Krajcarz, Maciej T.; Laughlan, Lana; Rabeder, Gernot; Sabol, Martin; Wojtal, Piotr; Bocherens, Hervé

    2016-01-01

    Collagen, the organic fraction of bone, records the isotopic parameters of consumed food for carbon (δ13C) and nitrogen (δ15N). This relationship of isotopic signature between diet and tissue is an important tool for the study of dietary preferences of modern and fossil animal species. Since the first information on the isotopic signature of cave bear was reported, numerous data from Europe have become available. The goal of this work is to track the geographical variation of cave bear collagen isotopic values in Europe during Marine Isotopic Stage 3 (about 60,000-25,000 yr BP). In this study the results of new δ13C and δ15N isotopic analyses of cave bear collagen from four Central-Eastern European sites are presented, as well as a review of all published isotopic data for cave bears of the same period. The main conclusion is a lack of geographical East-West pattern in the variations of δ13C and δ15N values of cave bear collagen. Moreover, no relationship was found between cave bear taxonomy and isotopic composition. The cave bears from Central-Eastern Europe exhibit δ13C and δ15N values near the average of the range of Central, Western and Southern European cave bears. Despite the fact that most cave bear sites follow an altitudinal gradient, separate groups of sites exhibit shift in absolute values of δ13C, what disturbs an altitude-related isotopic pattern. The most distinct groups are: high Alpine sites situated over 1500 m a.s.l. - in terms of δ13C; and two Romanian sites Peştera cu Oase and Urşilor - in case of δ15N. Although the cave bear isotopic signature is driven by altitude, the altitudinal adjustment of isotopic data is not enough to explain the isotopic dissimilarity of these cave bears. The unusually high δ15N signature of mentioned Romanian sites is an isolated case in Europe. Cave bears from relatively closely situated Central-Eastern European sites and other Romanian sites are more similar to Western European than to Romanian

  15. Diploptene δ13C values from contemporary thermokarst lake sediments show complex spatial variation

    NASA Astrophysics Data System (ADS)

    Davies, Kimberley L.; Pancost, Richard D.; Edwards, Mary E.; Anthony, Katey M. Walter; Langdon, Peter G.; Chaves Torres, Lidia

    2016-05-01

    Cryospheric changes in northern high latitudes are linked to significant greenhouse gas flux to the atmosphere, for example, methane that originates from organic matter decomposition in thermokarst lakes. The set of pathways that link methane production in sediments, via oxidation in the lake system, to the flux of residual methane to the atmosphere is complex and exhibits temporal and spatial variation. The isotopic signal of bacterial biomarkers (hopanoids, e.g. diploptene) in sediments has been used to identify contemporary ocean-floor methane seeps and, in the geological record, periods of enhanced methane production (e.g. the PETM). The biomarker approach could potentially be used to assess temporal changes in lake emissions through the Holocene via the sedimentary biomarker record. However, there are no data on the consistency of the signal of isotopic depletion in relation to source or on the amount of noise (unexplained variation) in biomarker values from modern lake sediments. We assessed methane oxidation as represented by the isotopic signal of biomarkers from methane oxidising bacteria (MOB) in multiple surface sediment samples in three distinct areas known to emit varying levels of methane in two shallow Alaskan thermokarst lakes. Diploptene was present and had δ13C values lower than -38 ‰ in all sediments analysed, suggesting methane oxidation was widespread. However, there was considerable variation in δ13C values within each area. The most 13C-depleted diploptene was found in an area of high methane ebullition in Ace Lake (diploptene δ13C values between -68.2 and -50.1 ‰). In contrast, significantly higher diploptene δ13C values (between -42.9 and -38.8 ‰) were found in an area of methane ebullition in Smith Lake. δ13C values of diploptene between -56.8 and -46.9 ‰ were found in the centre of Smith Lake, where ebullition rates are low but diffusive methane efflux occurs. The small-scale heterogeneity of the samples may reflect patchy

  16. Synthesis and applications of selectively {sup 13}C-labeled RNA

    SciTech Connect

    SantaLucia, J. Jr.; Shen, L.X.; Lewis, H.; Cai, Z.; Tinoci, I. Jr.

    1994-12-01

    Spectral overlap is a substantial problem in NMR studies of RNA molecules >30 nucleotides. To overcome this difficulty, we synthesized selectively {sup 13}C-labeled RNAs and adapted several isotope-edited two- and three-dimensional NMR experiments originally developed for protein studies. We optimized protocols for synthesis of multi-gram quantities of CTP, UTp, ATP, and GTP using a combination of synthetic organic and enzymatic methods. Uracil is prepared in 40 to 50% yield from {sup 13}C-cyanide in two steps. Using acetyl- tribenzoyl-ribose and standard chemistry uracil is then attached to the sugar (90% yield). The tribenzoyl-uridine intermediate is converted into uridine or cytidine quantitatively, depending on the deblocking protocol. Labeled purines are synthesized using simple pyrimidine precursors and reacting with {sup 13}C-formic acid (80% yield). Purine nucleosides are then synthesized using uridine phosphorylase and purine nucleoside phosphorylase. The nucleosides were converted to NMPs by treatment with POC1{sub 3} in triethylphosphate. We converted NMPs to NTPs by standard enzymatic methods. Selectively labeled RNAs were synthesized by run-off transcription using {sup 13}C-labeled NTPs. Several different strategies help solve over-lap problems in larger RNAs. Isotope-edited two-dimensional NMR experiments such as {omega}1-1/2 X-filtered NOESY simplify NMR spectra by dividing the normal NOESY spectrum into two subspectra-one involving NOEs from protons bound to {sup 12}C and one from protons bound to {sup 13}C. For example, we labeled A and U residues of a 34-nucleotide pseudoknot, and the {sup 12}C subspectrum of the 1/2 X-filtered NOESY contained NOEs only from G and C residues (along with adenine 2H); the {sup 13}C subspectrum contained NOEs only from A and U residues. Each subspectrum has less overlap than the NOESY of an unlabeled sample; the editing strategy allows each resonance to be identified by residue type (A, C, G, or U).

  17. Towards coherent manipulation of the ground states of single cesium atom confined in a microscopic far-off-resonance optical dipole trap

    NASA Astrophysics Data System (ADS)

    Diao, Wenting; He, Jun; Liu, Bei; Wang, Junmin

    2012-11-01

    This work deals with the cooling and trapping of single cesium (Cs) atoms in a large-magnetic-gradient magneto-optical trap (MOT) and the confinement of single Cs atoms in a far-off-resonance optical dipole trap (FORT). The experiment setup is based on two large-numerical-aperture lens assemblies which allow us to strongly focus a 1064-nm TEM00-mode Gaussian laser beam to a 1/e2 radius of ~ 2.3 μm to form a microscopic FORT for isolating single atom with environment and to efficiently collect the laser-induced-fluorescence photons emitted by single atoms for detecting and recognizing single atom's internal state. We have tried both of "bottom-up" and "top-down" loading schemes to confine single atoms in the microscopic FORT. In the "bottom-up" scheme, we have successfully prepared single Cs atoms in the MOT and transferred it into FORT with a probability of almost 100%. In the "top-down" scheme, we have achieved ~ 74% of single atom loading probability in the FORT using light-assisted collisions induced by blue detuning laser and with prepared many Cs atoms in the MOT. The relaxation time in hyperfine level of ground state of trapped single Cs atom is measured to be ~5.4 s. To coherently manipulate atomic quantum bits (qubit) encoded in the clock states (mF = 0 states in Fg = 3 and 4 hyperfine levels) of single Cs atom via the two-photon simulated Raman adiabatic passage (STIRAP), we have prepared two phase-locked laser beams with a frequency difference of ~ 9.192 GHz by optically injecting an 852-nm master laser to lock the +1-order sideband of a 9-GHz current-modulated slave diode laser. The two phase-locked laser beams are used to drive STIRAP process in the Λ-type three-level system consists of Cs |6S1/2 Fg = 4, mF = 0> and |6S1/2 Fg = 3, mF = 0< long-lived clock states and Cs |6S1/2 Fe = 4, mF = +1 > excited state with the single-photon detuning of ~ -20 GHz. Rabi flopping experiments are in progress.

  18. Simple and accurate determination of global tau(R) in proteins using (13)C or (15)N relaxation data.

    PubMed

    Mispelter, J; Izadi-Pruneyre, N; Quiniou, E; Adjadj, E

    2000-03-01

    In the study of protein dynamics by (13)C or (15)N relaxation measurements different models from the Lipari-Szabo formalism are used in order to determine the motion parameters. The global rotational correlation time tau(R) of the molecule must be estimated prior to the analysis. In this Communication, the authors propose a new approach in determining an accurate value for tau(R) in order to realize the best fit of R(2) for the whole sequence of the protein, regardless of the different type of motions atoms may experience. The method first determines the highly structured regions of the sequence. For each corresponding site, the Lipari-Szabo parameters are calculated for R(1) and NOE, using an arbitrary value for tau(R). The chi(2) for R(2), summed over the selected sites, shows a clear minimum, as a function of tau(R). This minimum is used to better estimate a proper value for tau(R).

  19. Dipolar cross-relaxation modulates signal amplitudes in the 1H NMR spectrum of hyperpolarized [ 13C]formate

    NASA Astrophysics Data System (ADS)

    Merritt, Matthew E.; Harrison, Crystal; Mander, William; Malloy, Craig R.; Dean Sherry, A.

    2007-12-01

    The asymmetry in the doublet of a spin coupled to hyperpolarized 13C has been used previously to measure the initial polarization of 13C. We tested the hypothesis that a single observation of the 1H NMR spectrum of hyperpolarized 13C formate monitors 13C polarization. Depending on the microwave frequency during the polarization process, in-phase or out-of-phase doublets were observed in the 1H NMR spectrum. Even in this simple two-spin system, 13C polarization was not reflected in the relative area of the JCH doublet components due to strong heteronuclear cross-relaxation. The Solomon equations were used to model the proton signal as a function of time after polarization and to estimate 13C polarization from the 1H NMR spectra.

  20. Optical Potential Parameters of Weakly Bound Nuclear System 17F+13C

    NASA Astrophysics Data System (ADS)

    An, Guang-Peng; Lin, Cheng-Jian; Zhang, Huan-Qiao; Liu, Zu-Hua; Yang, Feng; Zhang, Gao-Long; Zhang, Chun-Lei; Wu, Zhen-Dong; Jia, Fei; Jia, Hui-Ming; Xu, Xin-Xing; Bai, Chun-Lin; Yu, Ning

    2008-12-01

    Elastic scattering angular distributions of the 14N+16O system and the angular distributions of transfer reaction 16O(14N,13 C)17 F at ELab = 76.2 MeV and 57MeV have been measured and calculated by means of the exact finite-range distorted-wave Born approximation with the PTOLEMY code. The optical potential parameters for the weakly bound nuclear system 17F+13 C have been deduced and applied to analyse the elastic scattering angular distributions of the similar systems 17F+12C and 17F+14N which are taken from literature. The result shows that the transfer reaction with stable projectile and target combination can be used as an alternative method to extract the optical potential parameters for the weakly bound nuclear system.

  1. NMR analyses of the cold cataract. III. /sup 13/C acrylamide studies

    SciTech Connect

    Lerman, S.; Megaw, J.M.; Moran, M.N.

    1985-10-01

    /sup 13/C-enriched acrylamide was employed to further delineate the action of this compound in preventing the cold cataract phenomenon when it is incorporated (in vitro) into young human and rabbit lenses. The extent of acrylamide incorporation, in the dark and with concurrent UV exposure, was monitored by /sup 13/C NMR spectroscopy. These studies provide further evidence that UV exposure causes permanent acrylamide photobinding within the lens. In such lenses, the gamma crystallin fraction of the soluble lens proteins is affected to the greatest extent. It appears to become aggregated and/or combined with the alpha and beta fractions resulting in an apparent loss of most of the gamma monomers. There is also an age-related effect with respect to the amount of acrylamide that can be incorporated into the lens. The decrease in acrylamide incorporation with age directly parallels the age-related decline in gamma crystallin levels.

  2. Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates

    NASA Astrophysics Data System (ADS)

    Tossell, J. A.

    1995-04-01

    13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2

  3. Characterization of covalent protein conjugates using solid-state sup 13 C NMR spectroscopy

    SciTech Connect

    Garbow, J.R.; Fujiwara, Hideji; Sharp, C.R.; Logusch, E.W. )

    1991-07-23

    Cross-polarization magic-angle spinning (CPMAS) {sup 13}C NMR spectroscopy has been used to characterize covalent conjugates of alachlor, an {alpha}-chloroacetamide hapten, with glutathione (GSH) and bovine serum albumin (BSA). The solid-state NMR method demonstrates definitively the covalent nature of these conjugates and can also be used to characterize the sites of hapten attachment to proteins. Three different sites of alachlor binding are observed in the BSA system. Accurate quantitation of the amount of hapten covalently bound to GSH and BSA is reported. The solid-state {sup 13}C NMR technique can easily be generalized to study other small molecule/protein conjugates and can be used to assist the development and refinement of synthetic methods needed for the successful formation of such protein alkylation products.

  4. (1)H-(13)C NMR-Based Profiling of Biotechnological Starch Utilization.

    PubMed

    Sundekilde, Ulrik K; Meier, Sebastian

    2016-10-04

    Starch is used in food- and nonfood applications as a renewable and degradable source of carbon and energy. Insight into the chemical detail of starch degradation remains challenging as the starch constituents amylose and amylopectin are homopolymers. We show that considerable molecular detail of starch fragmentation can be obtained from multivariate analysis of spectral features in optimized (1)H-(13)C NMR spectroscopy of starch fragments to identify relevant features that distinguish processes in starch utilization. As a case study, we compare the profiles of starch fragments in commercial beer samples. Spectroscopic profiles of homooligomeric starch fragments can be excellent indicators of process conditions. In addition, differences in the structure and composition of starch fragments have predictive value for downstream process output such as ethanol production from starch. Thus, high-resolution (1)H-(13)C NMR spectroscopic profiles of homooligomeric fragment mixtures in conjunction with chemometric methods provide a useful addition to the analytical chemistry toolbox of biotechnological starch utilization.

  5. 13C NMR spectroscopy of the insoluble carbon of carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Pizzarello, S.; Frye, J. S.

    1987-01-01

    13C NMR spectra have been obtained of the insoluble carbon residues resulting from HF-digestion of three carbonaceous chondrites, Orgueil (C1), Murchison (CM2), and Allende (CV3). Spectra obtained using the cross polarization magic-angle spinning technique show two major features attributable respectively to carbon in aliphatic/olefinic structures. The spectrum obtained from the Allende sample was weak, presumably as a consequence of its low hydrogen content. Single pulse excitation spectra, which do not depend on 1H-13C polarization transfer for signal enhancement were also obtained. These spectra, which may be more representative of the total carbon in the meteorite samples, indicate a greater content of carbon in aromatic/olefinic structures. These results suggest that extensive polycyclic aromatic sheets are important structural features of the insoluble carbon of all three meteorites. The Orgueil and Murchison materials contain additional hydrogenated aromatic/olefinic and aliphatic groups.

  6. Reconstructing past climate using a multi-specific 13C-approach

    NASA Astrophysics Data System (ADS)

    Ferrio, Juan Pedro; Aguilera, Mónica; Voltas, Jordi

    2010-05-01

    Carbon isotope composition (δ13C) in tree-rings has become routinely used in palaeoclimatic research for the assessment of changes in water availability in seasonally dry climates. Long tree-ring chronologies, however, are relatively scarce, whereas the original climate signal of wood δ13C is usually well preserved in fossil charcoal [1, 4] Accordingly, charcoal δ13C records are an alternative to classic dendroclimatology to characterize past changes in water availability (e.g. precipitation). In this work, we explore the potential for palaeoenvironmental research of two co-occuring Mediterranean species with contrasting strategies to cope with drought [2]: Aleppo pine (Pinus halepensis Mill.) and holm oak (Quercus ilex L.). We hypothesize that the differential sensitivity of pine and oak to climate variables can be exploited to refine palaeoclimate reconstructions based on δ13C in wood or charcoal. For this purpose, we put together published tree-core-δ13C data from 40 sites across Spain [2, 3] and new δ13C data from 15 sites where both species co-existed in mixed stands. The sites were selected to represent the range of variation in thermal and precipitation regimes for these species, while avoiding any correlation between precipitation and temperature across sites. Five dominant or codominant trees were selected per site, and microcores including the most recently formed tree rings were obtained with a Trephor tool [5]. Fragments were oven-dried at 60 ° C for 48 h and milled separately to a fine powder using a ball mill (Retsch MM301, Haan, Germany) for δ13C analysis. Current meteorological data (monthly estimates of air mean temperature (minimum, mean and maximum), precipitation and solar radiation) was obtained from the Digital Climatic Atlas of the Iberian Peninsula (http://opengis.uab.es/wms/iberia/index.htm) (spatial resolution of 200 m). A family of models (either linear or exponential) best predicting monthly and annual precipitation from δ13C

  7. Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds

    NASA Astrophysics Data System (ADS)

    Panich, A. M.; Sergeev, N. A.; Shames, A. I.; Osipov, V. Yu; Boudou, J.-P.; Goren, S. D.

    2015-02-01

    Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and 13C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of 13C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

  8. Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds.

    PubMed

    Panich, A M; Sergeev, N A; Shames, A I; Osipov, V Yu; Boudou, J-P; Goren, S D

    2015-02-25

    Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and (13)C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of (13)C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

  9. Determination of 15N/14N and 13C/12C in Solid and Aqueous Cyanides

    USGS Publications Warehouse

    Johnson, C.A.

    1996-01-01

    The stable isotopic compositions of nitrogen and carbon in cyanide compounds can be determined by combusting aliquots in sealed tubes to form N2 gas and CO2 gas and analyzing the gases by mass spectrometry. Free cyanide (CN-aq + HCNaq) in simple solutions can also be analyzed by first precipitating the cyanide as copper(II) ferrocyanide and then combusting the precipitate. Reproducibility is ??0.5??? or better for both ??15N and ??13C. If empirical corrections are made on the basis of carbon yields, the reproducibility of ??13C can be improved to ??0.2???. The analytical methods described herein are sufficiently accurate and precise to apply stable isotope techniques to problems of cyanide degradation in natural waters and industrial process solutions.

  10. C-13/C-12 ratio in methane from the flooded Amazon forest

    NASA Technical Reports Server (NTRS)

    Tyler, Stanley C.; Blake, Donald R.; Rowland, F. Sherwood

    1987-01-01

    The C1-C4 hydrocarbon concentrations and the C-13/C-12 ratio in CH4 detected in air samples collected in the Amazon region (3.5 deg S latitude and 5.9 deg W longitude) are analyzed. It is observed that the CH4 concentrations of each sample are enhanced over the background concentration for remote locations, and the C-13/C-12 ratio in this biogenic methane is depleted in C-13 relative to atmospheric CH4. It is concluded, from the C2-C4 hydrocarbon data, that minor yields of C2-C4 hyrocarbons are released coincident with CH4; however, the minor yields do not contribute to the regionally enhanced concentrations of hydrocarbons found in Amazonia and the global atmosphere release of C2-C4 compounds.

  11. Hyperpolarized 13C pyruvate mouse brain metabolism with absorptive-mode EPSI at 1 T

    NASA Astrophysics Data System (ADS)

    Miloushev, Vesselin Z.; Di Gialleonardo, Valentina; Salamanca-Cardona, Lucia; Correa, Fabian; Granlund, Kristin L.; Keshari, Kayvan R.

    2017-02-01

    The expected signal in echo-planar spectroscopic imaging experiments was explicitly modeled jointly in spatial and spectral dimensions. Using this as a basis, absorptive-mode type detection can be achieved by appropriate choice of spectral delays and post-processing techniques. We discuss the effects of gradient imperfections and demonstrate the implementation of this sequence at low field (1.05 T), with application to hyperpolarized [1-13C] pyruvate imaging of the mouse brain. The sequence achieves sufficient signal-to-noise to monitor the conversion of hyperpolarized [1-13C] pyruvate to lactate in the mouse brain. Hyperpolarized pyruvate imaging of mouse brain metabolism using an absorptive-mode EPSI sequence can be applied to more sophisticated murine disease and treatment models. The simple modifications presented in this work, which permit absorptive-mode detection, are directly translatable to human clinical imaging and generate improved absorptive-mode spectra without the need for refocusing pulses.

  12. Neutron yield from a thick 13C target irradiated by 90 MeV protons

    NASA Astrophysics Data System (ADS)

    Alyakrinskiy, O.; Andrighetto, A.; Barbui, M.; Brandenburg, S.; Cinausero, M.; Dalena, B.; Dendooven, P.; Fioretto, E.; Lhersonneau, G.; Lyapin, W.; Prete, G.; Simonetti, G.; Stroe, L.; Tecchio, L. B.; Trzaska, W. H.

    2005-08-01

    In the context of the design of an intense source of low and intermediate energy neutrons, the angular and energy distributions of neutrons produced in the interaction of 90 MeV protons in a 13C target, in which the protons are stopped, have been measured by time-of-flight and activation techniques. As compared to 12C the yield is less than a factor two higher, while it is somewhat less than for a 9Be target.

  13. Quantitative analysis of deuterium using the isotopic effect on quaternary (13)C NMR chemical shifts.

    PubMed

    Darwish, Tamim A; Yepuri, Nageshwar Rao; Holden, Peter J; James, Michael

    2016-07-13

    Quantitative analysis of specifically deuterated compounds can be achieved by a number of conventional methods, such as mass spectroscopy, or by quantifying the residual (1)H NMR signals compared to signals from internal standards. However, site specific quantification using these methods becomes challenging when dealing with non-specifically or randomly deuterated compounds that are produced by metal catalyzed hydrothermal reactions in D2O, one of the most convenient deuteration methods. In this study, deuterium-induced NMR isotope shifts of quaternary (13)C resonances neighboring deuterated sites have been utilized to quantify the degree of isotope labeling of molecular sites in non-specifically deuterated molecules. By probing (13)C NMR signals while decoupling both proton and deuterium nuclei, it is possible to resolve (13)C resonances of the different isotopologues based on the isotopic shifts and the degree of deuteration of the carbon atoms. We demonstrate that in different isotopologues, the same quaternary carbon, neighboring partially deuterated carbon atoms, are affected to an equal extent by relaxation. Decoupling both nuclei ((1)H, (2)H) resolves closely separated quaternary (13)C signals of the different isotopologues, and allows their accurate integration and quantification under short relaxation delays (D1 = 1 s) and hence fast accumulative spectral acquisition. We have performed a number of approaches to quantify the deuterium content at different specific sites to demonstrate a convenient and generic analysis method for use in randomly deuterated molecules, or in cases of specifically deuterated molecules where back-exchange processes may take place during work up.

  14. Deconvolution of the tree ring based delta/sup 13/C record

    SciTech Connect

    Peng, T.; Broecker, W.S.; Freyer, H.D.; Trumbore, S.

    1983-04-20

    We assumed that the tree-ring based /sup 13/C//sup 12/C record constructed by Freyer and Belacy (1983) to be representative of the fossil fuel and forest-soil induced /sup 13/C//sup 12/C change for atmospheric CO/sub 2/. Through the use of a modification of the Oeschger et al. ocean model, we have computed the contribution of the combustion of coal, oil, and natural gas to this observed /sup 13/C//sup 12/C change. A large residual remains when the tree-ring-based record is corrected for the contribution of fossil fuel CO/sub 2/. A deconvolution was performed on this residual to determine the time history and magnitude of the forest-soil reservoir changes over the past 150 years. Several important conclusions were reached. (1) The magnitude of the integrated CO/sub 2/ input from these sources was about 1.6 times that from fossil fuels. (2) The forest-soil contribution reached a broad maximum centered at about 1900. (3) Over the 2 decade period covered by the Mauna Loa atmospheric CO/sub 2/ content record, the input from forests and soils was about 30% that from fossil fuels. (4) The /sup 13/C//sup 12/C trend over the last 20 years was dominated by the input of fossil fuel CO/sub 2/. (5) The forest-soil release did not contribute significantly to the secular increase in atmospheric CO/sub 2/ observed over the last 20 years. (6) The pre-1850 atmospheric p2 values must have been in the range 245 to 270 x 10/sup -6/ atmospheres.

  15. (13)C-NMR Spectral Data of Alkaloids Isolated from Psychotria Species (Rubiaceae).

    PubMed

    Carvalho Junior, Almir Ribeiro de; Vieira, Ivo Jose Curcino; Carvalho, Mario Geraldo de; Braz-Filho, Raimundo; S Lima, Mary Anne; Ferreira, Rafaela Oliveira; José Maria, Edmilson; Oliveira, Daniela Barros de

    2017-01-11

    The genus Psychotria (Rubiaceae) comprises more than 2000 species, mainly found in tropical and subtropical forests. Several studies have been conducted concerning their chemical compositions, showing that this genus is a potential source of alkaloids. At least 70 indole alkaloids have been identified from this genus so far. This review aimed to compile (13)C-NMR data of alkaloids isolated from the genus Psychotria as well as describe the main spectral features of different skeletons.

  16. On the status of IAEA delta-13C stable isotope reference materials.

    NASA Astrophysics Data System (ADS)

    Assonov, Sergey; Groening, Manfred; Fajgelj, Ales

    2016-04-01

    For practical reasons all isotope measurements are performed on relative scales realized through the use of international, scale-defining primary standards. In fact these standards were materials (artefacts, similar to prototypes of meter and kg) selected based on their properties. The VPDB delta-13C scale is realised via two highest-level reference materials NBS19 and LSVEC, the first defining the scale and the second aimed to normalise lab-to-lab calibrations. These two reference materials (RMs) have been maintained and distributed by IAEA and NIST. The priority task is to maintain these primary RMs at the required uncertainty level, thus ensuring the long-term scale consistency. The second task is to introduce replacements when needed (currently for exhausted NBS19, work in progress). The next is to produce a family of lower level RMs (secondary, tertiary) addressing needs of various applications (with different delta values, in different physical-chemical forms) and their needs for the uncertainty; these RMs should be traceable to the highest level RMs. Presently three is a need for a range of RMs addressing existing and newly emerging analytical techniques (e.g. optical isotopic analysers) in form of calibrated CO2 gases with different delta-13C values. All that implies creating a family of delta-13C stable isotope reference materials. Presently IAEA works on replacement for NBS19 and planning new RMs. Besides, we found that LSVEC (introduced as second anchor for the VPDB scale in 2006) demonstrate a considerable scatter of its delta-13C value which implies a potential bias of the property value and increased value uncertainty which may conflict with uncertainty requirements for atmospheric monitoring. That is not compatible with the status of LSVEC, and therefore it should be replaced as soon as possible. The presentation will give an overview of the current status, the strategic plan of developments and the near future steps.

  17. 15N and 13C NMR Determination of Allantoin Metabolism in Developing Soybean Cotyledons 1

    PubMed Central

    Coker, George T.; Schaefer, Jacob

    1985-01-01

    The metabolism of allantoin by immature cotyledons of soybean (Glycine max L. cv Elf) grown in culture was investigated using solid state 13C and 15N nuclear magnetic resonance. All of the nitrogens of allantoin were incorporated into protein in a manner similar to that of each other and to the amide nitrogen of glutamine. The C-2 of allantoin was not incorporated into cellular material; presumably it was lost as CO2. About 50% of the C-5 of allantoin was incorporated into cellular material as a methylene carbon; the other 50% was presumably also lost as CO2. The 13C-15N bonds of [5-13C;1-15N] and [2-13C;1,3-15N]allantoin were broken prior to the incorporation of the nitrogens into protein. These data are consistent with allantoin's degradation to two molecules of urea and one two-carbon fragment. Cotyledons grown on allantoin as a source of nitrogen accumulated 21% of the nitrogen of cotyledons grown on glutamine. Only 50% of the nitrogen of the degraded allantoin was incorporated into the cotyledon as organic nitrogen; the other 50% was recovered as NH4+ in the media in which the cotyledons had been grown. The latter results suggests that the lower accumulation of nitrogen by cotyledons grown on allantoin was in part due to failure to assimilate NH4+ produced from allantoin. The seed coats had a higher activity of glutamine synthetase and a higher rate of allantoin degradation than cotyledons indicating that seed coats play an important role in the assimilation and degradation of allantoin. PMID:16663995

  18. 1H and 13C NMR assignments for two new angular furanocoumarin glycosides from Peucedanum praeruptorum.

    PubMed

    Chang, Haitao; Okada, Yoshihito; Okuyama, Toru; Tu, Pengfei

    2007-07-01

    Two novel angular-type furanocoumarin glycosides, peucedanoside A (1) and peucedanoside B (2), along with a known compound apterin (3), were isolated from the roots of Peucedanum praeruptorum Dunn. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments including DEPT, HSQC, HMBC and ROESY.

  19. A deconvolution of the tree ring based δ13C record

    NASA Astrophysics Data System (ADS)

    Peng, Tsung-Hung; Broecker, Wallace S.; Freyer, Hans D.; Trumbore, Susan

    1983-04-01

    We assumed that the tree-ring-based 13C/12C record constructed by Freyer and Belacy (1983) to be representative of the fossil fuel and forest-soil induced 13C/12C change for atmospheric CO2. Through the use of a modification of the Oeschger et al. ocean model, we have computed the contribution of the combustion of coal, oil, and natural gas to this observed 13C/12C change. A large residual remains when the tree-ring-based record is corrected for the contribution of fossil fuel CO2. A deconvolution was performed on this residual to determine the time history and magnitude of the forest-soil reservoir changes over the past 150 years. Several important conclusions were reached. (1) The magnitude of the integrated CO2 input from these sources was about 1.6 times that from fossil fuels. (2) The forest-soil contribution reached a broad maximum centered at about 1900. (3) Over the 2 decade period covered by the Mauna Loa atmospheric CO2 content record, the input from forests and soils was about 30% that from fossil fuels. (4) The 13C/12C trend over the last 20 years was dominated by the input of fossil fuel CO2. (5) The forest-soil release did not contribute significantly to the secular increase in atmospheric CO2 observed over the last 20 years. (6) The pre-1850 atmospheric ?values must have been in the range 245 to 270×10-6 atmospheres.

  20. Tracing solid waste leachate in groundwater using δ13 C from dissolved inorganic carbon.

    PubMed

    Haarstad, Ketil; Mæhlum, Trond

    2013-01-01

    Tracers can be used to monitor emissions of leachate from landfills in order to detect hydrological pathways and to evaluate environmental pollution. We investigated the stable carbon isotope ratio (δ(13)C-Σ CO (2)) in dissolved inorganic carbon and tritium ((3)H) in water, in addition to the tracers of pollution commonly found in relatively high concentrations in leachate, such as chloride (Cl), organic matter (COD), nitrogen (total and NH(4)-N), iron (Fe), electrical conductivity (EC) and pH. The sampling was performed at seven landfills in the south-eastern part of Norway during a period of 5 years. The objective was to evaluate the potential for tracing leachate in the environment with emphasis on groundwater pollution. By measuring the δ(13)C-Σ CO (2) in leachates, groundwaters and surface waters, the influence of leachate can be identified. The value of δ(13)C-Σ CO (2) varied from-5.5 to 25.9 ‰ in leachate, from-25.4 to 14.7 ‰ in groundwater and from-19.7 to-13.1 ‰ in creeks. A comparison of the carbon isotope ratio with COD, EC and the concentrations of total and NH (4)-N, Cl and Fe showed that δ(13)C-Σ CO (2) is a good tracer for leachate due to higher sensitivity compared to other parameters. The mean concentrations of all the studied parameters were higher in the leachate samples; however, only the carbon isotope ratio showed significant differences between all the groups with strong and middle pollution and samples with low pollution, showing that it can be used as a convenient tracer for leachate in groundwater and surface water. The carbon isotope ratio showed strong correlation between nitrogen, EC and bicarbonate, but not with pH. Tritium was only sporadically found in measureable concentrations and is not considered as a suitable tracer at the sampled locations.

  1. Quantifying the chemical composition of soil organic carbon with solid-state 13C NMR

    NASA Astrophysics Data System (ADS)

    Baldock, J. A.; Sanderman, J.

    2011-12-01

    The vulnerability of soil organic carbon (SOC) to biological decomposition and mineralisation to CO2 is defined at least partially by its chemical composition. Highly aromatic charcoal-like SOC components are more stable to biological decomposition than other forms of carbon including cellulose. Solid-state 13C NMR has gained wide acceptance as a method capable of defining SOC chemical composition and mathematical fitting processes have been developed to estimate biochemical composition. Obtaining accurate estimates depends on an ability to quantitatively detect all carbon present in a sample. Often little attention has been paid to defining the proportion of organic carbon present in a soil that is observable in solid-state 13C NMR analyses of soil samples. However, if such data is to be used to inform carbon cycling studies, it is critical that quantitative assessments of SOC observability be undertaken. For example, it is now well established that a significant discrimination exists against the detection of the low proton content polyaromatic structures typical of charcoal using cross polarisation 13C NMR analyses. Such discrimination does not exist where direct polarisation analyses are completed. In this study, the chemical composition of SOC as defined by cross polarisation and direct polarisation13C NMR analyses will be compared for Australian soils collected from under a diverse range of agricultural managements and climatic conditions. Results indicate that where significant charcoal C contents exist, it is highly under-represented in the acquired CP spectra. For some soils, a discrimination against alkyl carbon was also evident. The ability to derive correction factors to compensate for such discriminations will be assessed and presented.

  2. 13C-18O isotope signatures and ‘clumped isotope’ thermometry in foraminifera and coccoliths

    NASA Astrophysics Data System (ADS)

    Tripati, Aradhna K.; Eagle, Robert A.; Thiagarajan, Nivedita; Gagnon, Alexander C.; Bauch, Henning; Halloran, Paul R.; Eiler, John M.

    2010-10-01

    Accurate constraints on past ocean temperatures and compositions are critical for documenting climate change and resolving its causes. Most proxies for temperature are not thermodynamically based, appear to be subject to biological processes, require regional calibrations, and/or are influenced by fluid composition. As a result, their interpretation becomes uncertain when they are applied in settings not necessarily resembling those in which they were empirically calibrated. Independent proxies for past temperature could provide an important means of testing and/or expanding on existing reconstructions. Here we report measurements of abundances of stable isotopologues of calcitic and aragonitic benthic and planktic foraminifera and coccoliths, relate those abundances to independently estimated growth temperatures, and discuss the possible scope of equilibrium and kinetic isotope effects. The proportions of 13C- 18O bonds in these samples exhibits a temperature dependence that is generally similar to that previously been reported for inorganic calcite and other biologically precipitated carbonate-containing minerals (apatite from fish, reptile, and mammal teeth; calcitic brachiopods and molluscs; aragonitic coral and mollusks). Most species that exhibit non-equilibrium 18O/ 16O (δ 18O) and 13C/ 12C (δ 13C) ratios are characterized by 13C- 18O bond abundances that are similar to inorganic calcite and are generally indistinguishable from apparent equilibrium, with possible exceptions among benthic foraminiferal samples from the Arctic Ocean where temperatures are near-freezing. Observed isotope ratios in biogenic carbonates can be explained if carbonate minerals generally preserve a state of ordering that reflects the extent of isotopic equilibration of the dissolved inorganic carbon species.

  3. EDGE2D Simulations of JET{sup 13}C Migration Experiments

    SciTech Connect

    J.D. Strachan; J.P. Coad; G. Corrigan; G.F. Matthews; J. Spence

    2004-06-16

    Material migration has received renewed interest due to tritium retention associated with carbon transport to remote vessel locations. Those results influence the desirability of carbon usage on ITER. Subsequently, additional experiments have been performed, including tracer experiments attempting to identify material migration from specific locations. In this paper, EDGE2D models a well-diagnosed JET{sup 13}C tracer migration experiment. The role of SOL flows upon the migration patterns is identified.

  4. Cardiac perfusion imaging using hyperpolarized 13c urea using flow sensitizing gradients

    PubMed Central

    Miller, Jack J.; Robson, Matthew D.; Tyler, Damian J.

    2015-01-01

    Purpose To demonstrate the feasibility of imaging the first passage of a bolus of hyperpolarized 13C urea through the rodent heart using flow‐sensitizing gradients to reduce signal from the blood pool. Methods A flow‐sensitizing bipolar gradient was optimized to reduce the bright signal within the cardiac chambers, enabling improved contrast of the agent within the tissue capillary bed. The gradient was incorporated into a dynamic golden angle spiral 13C imaging sequence. Healthy rats were scanned during rest (n = 3) and under adenosine stress‐induced hyperemia (n = 3). Results A two‐fold increase in myocardial perfusion relative to rest was detected during adenosine stress‐induced hyperemia, consistent with a myocardial perfusion reserve of two in rodents. Conclusion The new pulse sequence was used to obtain dynamic images of the first passage of hyperpolarized 13C urea in the rodent heart, without contamination from bright signal within the neighboring cardiac lumen. This probe of myocardial perfusion is expected to enable new hyperpolarized 13C studies in which the cardiac metabolism/perfusion mismatch can be identified. Magn Reson Med, 2015. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Magn Reson Med 75:1474–1483, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance. PMID:25991580

  5. A comparison of quantitative methods for clinical imaging with hyperpolarized (13)C-pyruvate.

    PubMed

    Daniels, Charlie J; McLean, Mary A; Schulte, Rolf F; Robb, Fraser J; Gill, Andrew B; McGlashan, Nicholas; Graves, Martin J; Schwaiger, Markus; Lomas, David J; Brindle, Kevin M; Gallagher, Ferdia A

    2016-04-01

    Dissolution dynamic nuclear polarization (DNP) enables the metabolism of hyperpolarized (13)C-labelled molecules, such as the conversion of [1-(13)C]pyruvate to [1-(13)C]lactate, to be dynamically and non-invasively imaged in tissue. Imaging of this exchange reaction in animal models has been shown to detect early treatment response and correlate with tumour grade. The first human DNP study has recently been completed, and, for widespread clinical translation, simple and reliable methods are necessary to accurately probe the reaction in patients. However, there is currently no consensus on the most appropriate method to quantify this exchange reaction. In this study, an in vitro system was used to compare several kinetic models, as well as simple model-free methods. Experiments were performed using a clinical hyperpolarizer, a human 3 T MR system, and spectroscopic imaging sequences. The quantitative methods were compared in vivo by using subcutaneous breast tumours in rats to examine the effect of pyruvate inflow. The two-way kinetic model was the most accurate method for characterizing the exchange reaction in vitro, and the incorporation of a Heaviside step inflow profile was best able to describe the in vivo data. The lactate time-to-peak and the lactate-to-pyruvate area under the curve ratio were simple model-free approaches that accurately represented the full reaction, with the time-to-peak method performing indistinguishably from the best kinetic model. Finally, extracting data from a single pixel was a robust and reliable surrogate of the whole region of interest. This work has identified appropriate quantitative methods for future work in the analysis of human hyperpolarized (13)C data.

  6. 13C 12C exchange between calcite and graphite: A possible thermometer in Grenville marbles

    USGS Publications Warehouse

    Valley, J.W.; O'Neil, J.R.

    1981-01-01

    The fractionation of 13C between calcite and graphite, ??(Cc-Gr). is consistently small (2.6-4.8 permil) in 34 assemblages from upper amphibolite- and granulite-facies marbles of the Grenville Province. In 25 samples from the Adirondack Mountains, New York, it decreases regularly with increasing metamorphic temperature. The fractionations are independent of absolute ??13C values of calcite (-2.9 to +5.0). For T = 600-800??C, the Adirondack data are described by ??(Cc-Gr) = -0.00748T (??C) + 8.68. This good correlation between ?? and T suggests that carbon isotope equilibrium was attained in these high-grade marbles and that the theoretical calculations of this fractionation by Bottinga are approximately 2 permil too large in this temperature range. Because of the relatively high temperature sensitivity suggested by these results and by Bottinga's calculations, and the pressure independence of isotope fractionation, ??(Cc-Gr) may provide a very good thermometer for high-grade marbles. Comparison of this field calibration for ??(Cc-Gr) vs temperature with results from other terranes supports the utility of ??(Cc-Gr) for geothermometry and suggests that graphite is much more sluggish to exchange than calcite, that exchange between calcite and graphite occurs at temperatures as low as 300??C, and that equilibrium may normally be attained only when peak metamorphic temperatures are greater than 500-600??C. Because 13C exchange is an unavoidable metamorphic process at temperatures above 300??C, high values of ??13C(Gr) in moderate- to high-grade carbonate-bearing rocks do not provide a sufficient criterion to infer an abiogenic origin for the graphite. ?? 1981.

  7. Analysis of defect structure in silicon. Characterization of samples from UCP ingot 5848-13C

    NASA Technical Reports Server (NTRS)

    Natesh, R.; Guyer, T.; Stringfellow, G. B.

    1982-01-01

    Statistically significant quantitative structural imperfection measurements were made on samples from ubiquitous crystalline process (UCP) Ingot 5848 - 13 C. Important trends were noticed between the measured data, cell efficiency, and diffusion length. Grain boundary substructure appears to have an important effect on the conversion efficiency of solar cells from Semix material. Quantitative microscopy measurements give statistically significant information compared to other microanalytical techniques. A surface preparation technique to obtain proper contrast of structural defects suitable for QTM analysis was perfected.

  8. Degradation of Mustard on Moist Sand, Asphalt, and Limestone Using 13C SSMAS NMR

    DTIC Science & Technology

    2006-12-01

    ASPHALT, AND LIMESTONE USING 13C SSMAS NMR Carol A. S. Brevett Carroll L. Cook Robert G. Nickol SA•C SAIC Abingdon, MD 21009 Kenneth B. Sumpter Monicia R...Cook, Carroll L.; Robert G. Nickol (SAIC);* Sumpter, Kenneth B.; Hall, Monicia R. (ECBC) Se. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING...James Savage, H. Dupont Durst , and Mark Brickhouse for programmatic support. 3 Blank CONTENTS 1. INTRODU CTION

  9. Phenotypic Analysis of Individuals With Costello Syndrome due to HRAS p.G13C

    PubMed Central

    Gripp, Karen W.; Hopkins, Elizabeth; Sol-Church, Katia; Stabley, Deborah L.; Axelrad, Marni E.; Doyle, Daniel; Dobyns, William B.; Hudson, Cindy; Johnson, John; Tenconi, Romano; Graham, Gail E.; Sousa, Ana Berta; Heller, Raoul; Piccione, Maria; Corsello, Giovanni; Herman, Gail E.; Tartaglia, Marco; Lin, Angela E.

    2014-01-01

    Costello syndrome is characterized by severe failure-to-thrive, short stature, cardiac abnormalities (heart defects, tachyarrhythmia, and hypertrophic cardiomyopathy (HCM)), distinctive facial features, a predisposition to papillomata and malignant tumors, postnatal cerebellar overgrowth resulting in Chiari 1 malformation, and cognitive disabilities. De novo germline mutations in the proto-oncogene HRAS cause Costello syndrome. Most mutations affect the glycine residues in position 12 or 13, and more than 80% of patients share p.G12S. To test the hypothesis that subtle genotype–phenotype differences exist, we report the first cohortcomparison between 12 Costello syndrome individuals with p.G13C and individuals with p.G12S. The individuals with p.G13C had many typical findings including polyhydramnios, failure-to-thrive, HCM, macrocephaly with posterior fossa crowding, and developmental delay. Subjectively, their facial features were less coarse. Statistically significant differences included the absence of multifocal atrial tachycardia (P-value =0.033), ulnar deviation of the wrist (P <0.001) and papillomata (P =0.003), and fewer neurosurgical procedures (P =0.024). Fewer individuals with p.G13C had short stature (height below −2 SD) without use of growth hormone (P <0.001). The noteworthy absence of malignant tumors did not reach statistical significance. Novel ectodermal findings were noted in individuals with p.G13C, including loose anagen hair resulting in easily pluckable hair with a matted appearance, different from the tight curls typical for most Costello syndrome individuals. Unusually long eye lashes requiring trimming are a novel finding we termed dolichocilia. These distinctive ectodermal findings suggest a cell type specific effect of this particular mutation. Additional patients are needed to validate these findings. PMID:21438134

  10. Phenotypic analysis of individuals with Costello syndrome due to HRAS p.G13C.

    PubMed

    Gripp, Karen W; Hopkins, Elizabeth; Sol-Church, Katia; Stabley, Deborah L; Axelrad, Marni E; Doyle, Daniel; Dobyns, William B; Hudson, Cindy; Johnson, John; Tenconi, Romano; Graham, Gail E; Sousa, Ana Berta; Heller, Raoul; Piccione, Maria; Corsello, Giovanni; Herman, Gail E; Tartaglia, Marco; Lin, Angela E

    2011-04-01

    Costello syndrome is characterized by severe failure-to-thrive, short stature, cardiac abnormalities (heart defects, tachyarrhythmia, and hypertrophic cardiomyopathy (HCM)), distinctive facial features, a predisposition to papillomata and malignant tumors, postnatal cerebellar overgrowth resulting in Chiari 1 malformation, and cognitive disabilities. De novo germline mutations in the proto-oncogene HRAS cause Costello syndrome. Most mutations affect the glycine residues in position 12 or 13, and more than 80% of patients share p.G12S. To test the hypothesis that subtle genotype-phenotype differences exist, we report the first cohort comparison between 12 Costello syndrome individuals with p.G13C and individuals with p.G12S. The individuals with p.G13C had many typical findings including polyhydramnios, failure-to-thrive, HCM, macrocephaly with posterior fossa crowding, and developmental delay. Subjectively, their facial features were less coarse. Statistically significant differences included the absence of multifocal atrial tachycardia (P-value = 0.033), ulnar deviation of the wrist (P < 0.001) and papillomata (P = 0.003), and fewer neurosurgical procedures (P = 0.024). Fewer individuals with p.G13C had short stature (height below -2 SD) without use of growth hormone (P < 0.001). The noteworthy absence of malignant tumors did not reach statistical significance. Novel ectodermal findings were noted in individuals with p.G13C, including loose anagen hair resulting in easily pluckable hair with a matted appearance, different from the tight curls typical for most Costello syndrome individuals. Unusually long eye lashes requiring trimming are a novel finding we termed dolichocilia. These distinctive ectodermal findings suggest a cell type specific effect of this particular mutation. Additional patients are needed to validate these findings.

  11. Sensitivity and specificity of an abbreviated 13C-mixed triglyceride breath test for measurement of pancreatic exocrine function

    PubMed Central

    Meier, Viola; Wolfram, Kristina U; Rosien, Ulrich; Layer, Peter

    2014-01-01

    Background A modified 13C-mixed triglyceride breath test (13C -MTGT) detects moderate pancreatic exocrine insufficiency noninvasively and reliably, but it requires prolonged breath sampling (6 hours (hr)). Objective We aimed to investigate whether 13C -MTGT can be abbreviated, to optimize clinical usability. Methods We analyzed the 13C-MTGT of 200 consecutive patients, retrospectively. Cumulative 1–5 hr 13C-exhalation values were compared with the standard parameter (6-hr cumulative 13C-exhalation). We determined the sensitivity and specificity of shortened breath sampling periods, by comparison with the normal values from 10 healthy volunteers, whom also underwent a secretin test to quantitate pancreatic secretion. Moreover, we evaluated the influence of gastric emptying (GE), using a 13C-octanoic acid breath test in a subset (N = 117). Results The 1–5 hr cumulative 13C-exhalation tests correlated highly and significantly with the standard parameter (p < 0.0001). Sensitivity for detection of impaired lipolysis was high (≥77%), but the specificity was low (≥38%) for the early measurements. Both parameters were high after 4 hrs (88% and 94%, respectively) and 5 hrs (98% and 91%, respectively). Multivariate linear correlation analysis confirmed that GE strongly influenced early postprandial 13C-exhalation during the 13C-MTGT. Conclusion Shortening of the 13C -MTGT from 6 to 4 hrs of duration was associated with similar diagnostic accuracy, yet increased clinical usability. The influence of GE on early postprandial results of the 13C-MTGT precluded further abbreviation of the test. PMID:25083286

  12. Real-time cardiac metabolism assessed with hyperpolarized [1-13C]acetate in a large-animal model

    PubMed Central

    Flori, Alessandra; Liserani, Matteo; Frijia, Francesca; Giovannetti, Giulio; Lionetti, Vincenzo; Casieri, Valentina; Positano, Vincenzo; Aquaro, Giovanni Donato; Recchia, Fabio A.; Santarelli, Maria Filomena; Landini, Luigi; Ardenkjaer-Larsen, Jan Henrik; Menichetti, Luca

    2014-01-01

    Dissolution-Dynamic Nuclear Polarization (dissolution-DNP) for Magnetic Resonance (MR) Spectroscopic Imaging has recently emerged as a novel technique for non invasive studies of the metabolic fate of biomolecules in vivo. Since acetate is the most abundant extra- and intra-cellular short-chain fatty acid, we focused on [1-13C]acetate as a promising candidate for a chemical probe to study myocardial metabolism of beating heart. Dissolution-DNP procedure of Na[1-13C]acetate for in vivo cardiac applications with 3T MR scanner was optimized in pigs during bolus injection of doses up to 3 mmoles. The Na[1-13C]acetate formulation was characterized by a liquid-state polarization of 14.2% and T1Eff in vivo of 17.6 ± 1.7 s. In vivo Na[1-13C]acetate kinetic displayed a bimodal shape: [1-13C]acetyl carnitine (AcC) was detected in a slice covering the cardiac volume, and the signal of 13C-acetate and 13C-AcC was modeled using the total Area Under the Curve (AUC) for kinetic analysis. A good correlation was found between the ratio AUC(AcC)/AUC(acetate) and the apparent kinetic constant of metabolic conversion kAcC/r1 from [1-13C]acetate to [1-13C]AcC. Our study proved the feasibility and limitations of administration of large doses of hyperpolarized [1-13C]acetate with dissolution DNP to study by MR spectroscopy the myocardial conversion of [1-13C]acetate in [1-13C]acetyl-carnitine generated by acetyltransferase in healthy pigs. PMID:25201079

  13. Paleoclimate record from Zidita Cave (Romania) using guano-derived δ13C isotopic data

    NASA Astrophysics Data System (ADS)

    Forray, Ferenc L.; Giurgiu, Alexandra; Onac, Bogdan P.; Tămaş, Tudor

    2014-05-01

    In this study, we measured the carbon isotopic composition of a core taken from a bat guano deposit in Zidita Cave (Metaliferi Mountains, Romania). The cave develops in Late Jurassic limestones, has a total length of 547 m, and its entrance was fortified during the XIV - XVIII centuries. The cave is a fossil maze with a filling represented by limestone blocks, clay sediments, and scarce calcite speleothems. The guano accumulation, 1.5 m thick, is located in a small room towards the end of the cave, under a Rhinolophus euryale roost site.The core was recovered with a Russian peat corer. 14C dating performed on the guano indicates a continuous deposition since ca. 500 years BP, but however, the upper first meter of the core has a modern age and high radiocarbon activity acquired from atmospheric radiocarbon bomb pulse. The core was sampled at 2 cm ± 2 mm intervals for δ13C analyses (76 samples) and at 5 cm for pollen. The investigations were carried out using a Picarro G2121-i δ13C analyzer (Combustion Module coupled with a Cavity Ring Down Spectroscopy technique) at the Stable Isotope Laboratory of the Department of Geology, Babes-Bolyai University (Cluj-Napoca, Romania). The result shows that guano δ13C range from -24.07 to -27.61 o‰The carbon isotopic profile indicates two major wet periods and 2 to 3 shorter periods characterized by drier climate.

  14. Neutron production by a 13C thick target irradiated by 20 90 MeV protons

    NASA Astrophysics Data System (ADS)

    Lhersonneau, G.; Malkiewicz, T.; Vakhtin, D.; Plokhoi, V.; Alyakrinskiy, O.; Barbui, M.; Brandenburg, S.; Dendooven, P.; Cinausero, M.; Kandiev, Ya.; Kettunen, H.; Khlebnikov, S.; Lyapin, V.; Penttilä, H.; Prete, G.; Rizzi, V.; Samarin, S.; Tecchio, L. B.; Trzaska, W. H.; Tyurin, G.

    2008-10-01

    Neutron production using an enriched 13C carbon converter has been measured during the design study of the italian RIB facility SPES. Energy and angular distributions of neutrons emitted by bombarding a 13C target of stopping length with protons in the range of 20 to 90 MeV have been measured by time-of-flight and activation and compared with the prediction of a Monte Carlo code developed at Snezhinsk. At the proton energy of 100 MeV, firstly envisaged for SPES, the gain with respect to a natural C target is less than a factor of two, while yields still compare well with those for 40 MeV deuterons on natural carbon adopted by SPIRAL-II. At energies near 30 MeV the 13C thick target is definitely more prolific than the target of natural carbon, but both yields with protons are clearly lower than the one with deuterons. At the energy of 20 MeV envisaged for a first stage of SPES it might be more efficient to irradiate the uranium target with protons rather than using the two-stage method with converter.

  15. (13) C-metabolic flux analysis of human adenovirus infection: Implications for viral vector production.

    PubMed

    Carinhas, Nuno; Koshkin, Alexey; Pais, Daniel A M; Alves, Paula M; Teixeira, Ana P

    2017-01-01

    Adenoviruses are human pathogens increasingly used as gene therapy and vaccination vectors. However, their impact on cell metabolism is poorly characterized. We performed carbon labeling experiments with [1,2-(13) C]glucose or [U-(13) C]glutamine to evaluate metabolic alterations in the amniocyte-derived, E1-transformed 1G3 cell line during production of a human adenovirus type 5 vector (AdV5). Nonstationary (13) C-metabolic flux analysis revealed increased fluxes of glycolysis (17%) and markedly PPP (over fourfold) and cytosolic AcCoA formation (nearly twofold) following infection of growing cells. Interestingly, infection of growth-arrested cells increased overall carbon flow even more, including glutamine anaplerosis and TCA cycle activity (both over 1.5-fold), but was unable to stimulate the PPP and was associated with a steep drop in AdV5 replication (almost 80%). Our results underscore the importance of nucleic and fatty acid biosynthesis for adenovirus replication. Overall, we portray a metabolic blueprint of human adenovirus infection, highlighting similarities with other viruses and cancer, and suggest strategies to improve AdV5 production. Biotechnol. Bioeng. 2017;114: 195-207. © 2016 Wiley Periodicals, Inc.

  16. (13)C-metabolic flux analysis of co-cultures: A novel approach.

    PubMed

    Gebreselassie, Nikodimos A; Antoniewicz, Maciek R

    2015-09-01

    In this work, we present a novel approach for performing (13)C metabolic flux analysis ((13)C-MFA) of co-culture systems. We demonstrate for the first time that it is possible to determine metabolic flux distributions in multiple species simultaneously without the need for physical separation of cells or proteins, or overexpression of species-specific products. Instead, metabolic fluxes for each species in a co-culture are estimated directly from isotopic labeling of total biomass obtained using conventional mass spectrometry approaches such as GC-MS. In addition to determining metabolic fluxes, this approach estimates the relative population size of each species in a mixed culture and inter-species metabolite exchange. As such, it enables detailed studies of microbial communities including species dynamics and interactions between community members. The methodology is experimentally validated here using a co-culture of two E. coli knockout strains. Taken together, this work greatly extends the scope of (13)C-MFA to a large number of multi-cellular systems that are of significant importance in biotechnology and medicine.

  17. SUMOFLUX: A Generalized Method for Targeted 13C Metabolic Flux Ratio Analysis.

    PubMed

    Kogadeeva, Maria; Zamboni, Nicola

    2016-09-01

    Metabolic fluxes are a cornerstone of cellular physiology that emerge from a complex interplay of enzymes, carriers, and nutrients. The experimental assessment of in vivo intracellular fluxes using stable isotopic tracers is essential if we are to understand metabolic function and regulation. Flux estimation based on 13C or 2H labeling relies on complex simulation and iterative fitting; processes that necessitate a level of expertise that ordinarily preclude the non-expert user. To overcome this, we have developed SUMOFLUX, a methodology that is broadly applicable to the targeted analysis of 13C-metabolic fluxes. By combining surrogate modeling and machine learning, we trained a predictor to specialize in estimating flux ratios from measurable 13C-data. SUMOFLUX targets specific flux features individually, which makes it fast, user-friendly, applicable to experimental design and robust in terms of experimental noise and exchange flux magnitude. Collectively, we predict that SUMOFLUX's properties realistically pave the way to high-throughput flux analyses.

  18. (13)C-metabolic flux analysis in S-adenosyl-L-methionine production by Saccharomyces cerevisiae.

    PubMed

    Hayakawa, Kenshi; Kajihata, Shuichi; Matsuda, Fumio; Shimizu, Hiroshi

    2015-11-01

    S-Adenosyl-L-methionine (SAM) is a major biological methyl group donor, and is used as a nutritional supplement and prescription drug. Yeast is used for the industrial production of SAM owing to its high intracellular SAM concentrations. To determine the regulation mechanisms responsible for such high SAM production, (13)C-metabolic flux analysis ((13)C-MFA) was conducted to compare the flux distributions in the central metabolism between Kyokai no. 6 (high SAM-producing) and S288C (control) strains. (13)C-MFA showed that the levels of tricarboxylic acid (TCA) cycle flux in SAM-overproducing strain were considerably increased compared to those in the S228C strain. Analysis of ATP balance also showed that a larger amount of excess ATP was produced in the Kyokai 6 strain because of increased oxidative phosphorylation. These results suggest that high SAM production in Kyokai 6 strains could be attributed to enhanced ATP regeneration with high TCA cycle fluxes and respiration activity. Thus, maintaining high respiration efficiency during cultivation is important for improving SAM production.

  19. Evidence of Anomalously Low δ13C of Marine Organic Matter in an Arctic Fjord

    NASA Astrophysics Data System (ADS)

    Kumar, Vikash; Tiwari, Manish; Nagoji, Siddhesh; Tripathi, Shubham

    2016-11-01

    Accurate estimation of relative carbon deposition (marine vs. terrestrial) is required for understanding the global carbon budget, particularly in the Arctic region, which holds disproportionate importance with respect to global carbon cycling. Although the sedimentary organic matter (SOM) concentration and its isotopic composition are important tools for such calculations, uncertainties loom over estimates provided by organic-geochemical bulk parameters. We report carbon and nitrogen concentrations and isotopes (δ13C and δ15N) of SOM at an Arctic fjord namely Kongsfjorden. We find that the bound inorganic nitrogen (ammonium attached to the clay minerals) forms a significant proportion of total nitrogen concentration (~77% in the inner fjord to ~24% in the outer part). On removing the bound nitrogen, the C/N ratio shows that the SOM in the inner fjord is made up of terrestrial carbon while the outer fjord shows mixed marine-terrestrial signal. We further show that the marine organic matter is unusually more depleted in 13C (~‑24‰) than the terrestrial organic matter (~‑22.5‰). This particular finding also helps explain high δ13C values of SOM as noted by earlier studies in central Arctic sediments despite a high terrestrial contribution.

  20. Dynamic nuclear polarization of carbonyl and methyl 13C spins in acetate using trityl OX063

    NASA Astrophysics Data System (ADS)

    Niedbalski, Peter; Parish, Christopher; Lumata, Lloyd

    2015-03-01

    Hyperpolarization via dissolution dynamic nuclear polarization (DNP) is a physics technique that amplifies the magnetic resonance signals by several thousand-fold for biomedical NMR spectroscopy and imaging (MRI). Herein we have investigated the effect of carbon-13 isotopic location on the DNP of acetate (one of the biomolecules commonly used for hyperpolarization) at 3.35 T and 1.4 K using a narrow ESR linewidth free radical trityl OX063. We have found that the carbonyl 13C spins yielded about twice the polarization produced in methyl 13C spins. Deuteration of the methyl group, beneficial in the liquid-state, did not produce an improvement in the polarization level at cryogenic conditions. Concurrently, the solid-state nuclear relaxation of these samples correlate with the polarization levels achieved. These results suggest that the location of the 13C isotopic labeling in acetate has a direct impact on the solid-state polarization achieved and is mainly governed by the nuclear relaxation leakage factor.

  1. 13C Tracers for Glucose Degrading Pathway Discrimination in Gluconobacter oxydans 621H

    PubMed Central

    Ostermann, Steffen; Richhardt, Janine; Bringer, Stephanie; Bott, Michael; Wiechert, Wolfgang; Oldiges, Marco

    2015-01-01

    Gluconobacter oxydans 621H is used as an industrial production organism due to its exceptional ability to incompletely oxidize a great variety of carbohydrates in the periplasm. With glucose as the carbon source, up to 90% of the initial concentration is oxidized periplasmatically to gluconate and ketogluconates. Growth on glucose is biphasic and intracellular sugar catabolism proceeds via the Entner–Doudoroff pathway (EDP) and the pentose phosphate pathway (PPP). Here we studied the in vivo contributions of the two pathways to glucose catabolism on a microtiter scale. In our approach we applied specifically 13C labeled glucose, whereby a labeling pattern in alanine was generated intracellularly. This method revealed a dynamic growth phase-dependent pathway activity with increased activity of EDP in the first and PPP in the second growth phase, respectively. Evidence for a growth phase-independent decarboxylation-carboxylation cycle around the pyruvate node was obtained from 13C fragmentation patterns of alanine. For the first time, down-scaled microtiter plate cultivation together with 13C-labeled substrate was applied for G. oxydans to elucidate pathway operation, exhibiting reasonable labeling costs and allowing for sufficient replicate experiments. PMID:26404385

  2. Evidence of Anomalously Low δ13C of Marine Organic Matter in an Arctic Fjord

    PubMed Central

    Kumar, Vikash; Tiwari, Manish; Nagoji, Siddhesh; Tripathi, Shubham

    2016-01-01

    Accurate estimation of relative carbon deposition (marine vs. terrestrial) is required for understanding the global carbon budget, particularly in the Arctic region, which holds disproportionate importance with respect to global carbon cycling. Although the sedimentary organic matter (SOM) concentration and its isotopic composition are important tools for such calculations, uncertainties loom over estimates provided by organic-geochemical bulk parameters. We report carbon and nitrogen concentrations and isotopes (δ13C and δ15N) of SOM at an Arctic fjord namely Kongsfjorden. We find that the bound inorganic nitrogen (ammonium attached to the clay minerals) forms a significant proportion of total nitrogen concentration (~77% in the inner fjord to ~24% in the outer part). On removing the bound nitrogen, the C/N ratio shows that the SOM in the inner fjord is made up of terrestrial carbon while the outer fjord shows mixed marine-terrestrial signal. We further show that the marine organic matter is unusually more depleted in 13C (~−24‰) than the terrestrial organic matter (~−22.5‰). This particular finding also helps explain high δ13C values of SOM as noted by earlier studies in central Arctic sediments despite a high terrestrial contribution. PMID:27827457

  3. Moss δ(13) C: an accurate proxy for past water environments in polar regions.

    PubMed

    Bramley-Alves, Jessica; Wanek, Wolfgang; French, Kristine; Robinson, Sharon A

    2015-06-01

    Increased aridity is of global concern. Polar regions provide an opportunity to monitor changes in bioavailable water free of local anthropogenic influences. However, sophisticated proxy measures are needed. We explored the possibility of using stable carbon isotopes in segments of moss as a fine-scale proxy for past bioavailable water. Variation in δ(13) C with water availability was measured in three species across three peninsulas in the Windmill Islands, East Antarctica and verified using controlled chamber experiments. The δ(13) C from Antarctic mosses accurately recorded long-term variations in water availability in the field, regardless of location, but significant disparities in δ(13) C between species indicated some make more sensitive proxies. δ(13) CSUGAR derived from living tissues can change significantly within the span of an Antarctic season (5 weeks) in chambers, but under field conditions, slow growth means that this technique likely represents multiple seasons. δ(13) CCELLULOSE provides a precise and direct proxy for bioavailable water, allowing reconstructions for coastal Antarctica and potentially other cold regions over past centuries.

  4. 14N + 13C fusion cross sections and compound nucleus limitation in 27Al

    NASA Astrophysics Data System (ADS)

    Digregorio, D. E.; Gomez del Campo, J.; Chan, Y. D.; Ford, J. L. C., Jr.; Shapira, D.; Ortiz, M. E.

    1982-10-01

    Fusion cross sections for the 14N + 13C system have been measured by detecting the evaporation residues at five bombarding energies which correspond to high excitation energies in the compound nucleus: E*(27Al)=64-110 MeV. The 27Al nucleus can be populated by four different heavy-ion entrance channels-15N + 12C, 16O + 11B, 14N + 13C, and 17O + 10B-which are accessible to experimental measurements. Comparing the present data with those already existing for the above channels, it is found that for E*>60 MeV the curves E* vs Jcr for each system converge, which may be indicative of a limitation imposed by the compound nucleus. The data are discussed in terms of existing models for entrance channel and statistical yrast line limitations. The highest energy point also suggests the existence of a maximum absolute angular momentum limit of ~28ℏ. NUCLEAR REACTIONS 14N + 13C E(14N)=86.0, 103.8, 149.0, 161.3, and 180.0 MeV; measured d2σdΩdE for reaction products from Z=5 to 12. Extracted σfus, σD, σR.

  5. Theoretical study of the structure of boron carbide B13C2

    NASA Astrophysics Data System (ADS)

    Shirai, Koun; Sakuma, Kyohei; Uemura, Naoki

    2014-08-01

    We have resolved long-standing discrepancies between the theoretical and experimental crystal structures of boron carbide B13C2. Theoretical studies predict that B13C2 should be stoichiometric and have the highest symmetry of the boron carbides. Experimentally, B13C2 is a semiconductor and many defect states have been reported, particularly in the CBC chain. Reconciling the disordered states of the chain, the chemical composition, and the lowest-energy state is problematic. We have solved this problem by constructing a structural model where approximately three-quarters of the unit cells contain (B11C)(CBC) and one-quarter of them contain (B12)(B4). This structural model explains many experimental results, such as the large thermal factors in x-ray diffraction and the broadening of the Raman spectra, without introducing unstable CBB chains. The model also solves the energy-gap problem. We show that there are many arrangements of these two types of unit cells, which are energetically almost degenerate. This demonstrates that boron carbides are well described by a geometrically frustrated system, similar to that proposed for β-rhombohedral boron.

  6. Temperature-mediated changes in microbial carbon use efficiency and 13C discrimination

    NASA Astrophysics Data System (ADS)

    Lehmeier, C. A.; Ballantyne, F., IV; Min, K.; Billings, S. A.

    2015-10-01

    Understanding how carbon dioxide (CO2) flux from soils feeds back to climate warming depends in part on our ability to quantify the efficiency with which microorganisms convert soil organic carbon (C) into either biomass or CO2. Quantifying ecosystem-level respiratory CO2 losses often also requires assumptions about stable C isotope fractionations associated with the microbial transformation of soil organic substrates. However, the diversity of organic substrates' δ13C and the challenges of measuring microbial C use efficiency (CUE) in soils fundamentally limit our ability to project soil, and thus ecosystem, C budgets in a warming climate. Here, we quantify the effect of temperature on C fluxes during metabolic transformations of cellobiose, a common microbial substrate, by a cosmopolitan soil microorganism growing at a constant rate. Specific respiration rate increased by 250 % between 13 and 26.5 °C, decreasing CUE from 77 to 56 %. Specific respiration rate was positively correlated with an increase in respiratory 13C discrimination from 4.4 to 6.7 ‰ across the same temperature range. This first demonstration of a direct link between temperature, microbial CUE and associated isotope fluxes provides a critical step towards understanding δ13C of respired CO2 at multiple scales, and towards a framework for predicting future soil C fluxes.

  7. Solid state (13)C NMR analysis of human gallstones from cancer and benign gall bladder diseases.

    PubMed

    Jayalakshmi, K; Sonkar, Kanchan; Behari, Anu; Kapoor, V K; Sinha, Neeraj

    2009-09-01

    Natural abundance (13)C cross polarized (CP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) analysis of human gall bladder stones collected from patients suffering from malignant and benign gall bladder disease was carried out which revealed different polymorphs of cholesterol in these stones. All gall bladder stones in present study had cholesterol as their main constituent. (13)C CP-MAS NMR analysis revealed three forms of cholesterol molecules in these stones, which are anhydrous form, monohydrate crystalline with amorphous form and monohydrate crystalline form. Our study revealed that stones collected from patients associated with chronic cholecystitis (CC) disease have mostly different polymorph of cholesterol than stones collected from patients associated with gall bladder cancer (GBC). Such study will be helpful in understanding the mechanism of formation of gallstones which are associated with different gall bladder diseases. This is the first study by solid state NMR revealing different crystal polymorphism of cholesterol in human gallstones, extending the applicability of (13)C CP-MAS NMR technique for the routine study of gallstones.

  8. Extreme 13C depletion of CCl2F2 in firn air samples from NEEM, Greenland

    NASA Astrophysics Data System (ADS)

    Zuiderweg, A.; Holzinger, R.; Martinerie, P.; Schneider, R.; Kaiser, J.; Witrant, E.; Etheridge, D.; Rubino, M.; Petrenko, V.; Blunier, T.; Röckmann, T.

    2012-07-01

    A series of 12 high volume air samples collected from the S2 firn core during the North Greenland Eemian Ice Drilling (NEEM) 2009 campaign have been measured for mixing ratio and stable carbon isotope composition of the chlorofluorocarbon CFC-12 (CCl2F2). While the mixing ratio measurements compare favorably to other firn air studies, the isotope results show extreme 13C depletion at the deepest measurable depth (65 m), to values lower than δ13C = -80‰ vs. VPDB (the international stable carbon isotope scale), compared to present day surface tropospheric measurements near -40‰. Firn air modeling was used to interpret these measurements. Reconstructed atmospheric time series indicate even larger depletions (to -120‰) near 1950 AD, with subsequent rapid enrichment of the atmospheric reservoir of the compound to the present day value. Mass-balance calculations show that this change must have been caused by a large change in the isotopic composition of anthropogenic CFC-12 emissions, probably due to technological changes in the CFC production process over the last 80 yr. Propagating the mass-balance calculations into the future demonstrates that as emissions decrease to zero, isotopic fractionation by the stratospheric sinks will lead to continued 13C enrichment in atmospheric CFC-12.

  9. Feasibility study of the 13C(α, n)16O reaction at LUNA

    NASA Astrophysics Data System (ADS)

    Kochanek, I.; Boeltzig, A.; Ciani, G. F.

    2017-03-01

    The 13C(α, n)16O reaction determines the dominant neutron source of the sprocess in thermally pulsing, low-mass, asymptotic giant branch (TP-AGB) stars. The temperature during the s-process in the 13C pocket of 90×106 K corresponds to a Gamow window of 140-230 keV. Since this energy is far below the Coulomb barrier, the cross section of this reaction is extremely small and its rate can only be extrapolated from the measurements at higher energies. At present, the cross section at Gamow peak is uncertain by almost one order of magnitude. An experimental campaign aimed at measuring low energy cross section in 13C(α n)16O is scheduled at the underground LUNA-400 accelerator in Gran Sasso Laboratory, Italy. The unique underground location of this facility offers significant improvement in sensitivity compared with previous investigations. It will allow to establish the interference pattern of the resonances and the absolute scale of this reaction.

  10. Metabolism of [U-13C]glucose in Human Brain Tumors In Vivo

    PubMed Central

    Maher, Elizabeth A.; Marin-Valencia, Isaac; Bachoo, Robert M.; Mashimo, Tomoyuki; Raisanen, Jack; Hatanpaa, Kimmo J.; Jindal, Ashish; Jeffrey, F. Mark; Choi, Changho; Madden, Christopher; Mathews, Dana; Pascual, Juan M.; Mickey, Bruce E.; Malloy, Craig R.; DeBerardinis, Ralph J.

    2012-01-01

    Glioblastomas (GBMs) and brain metastases demonstrate avid uptake of 18fluoro-2-deoxyglucose (FDG) by positron emission tomography (PET) and display perturbations of intracellular metabolite pools by 1H magnetic resonance spectroscopy (MRS). These observations suggest that metabolic reprogramming contributes to brain tumor growth in vivo. The Warburg effect, excess metabolism of glucose to lactate in the presence of oxygen, is a hallmark of cancer cells in culture. FDG-positive tumors are assumed to metabolize glucose in a similar manner, with high rates of lactate formation compared to mitochondrial glucose oxidation, but few studies have specifically examined the metabolic fates of glucose in vivo. In particular, the capacity of human brain malignancies to oxidize glucose in the tricarboxylic acid cycle is unknown. Here we studied the metabolism of human brain tumors in situ. [U-13C]glucose was infused during surgical resection, and tumor samples were subsequently subjected to 13C NMR spectroscopy. Analysis of tumor metabolites revealed lactate production, as expected. We also determined that pyruvate dehydrogenase, turnover of the TCA cycle, anaplerosis and de novo glutamine and glycine synthesis contributed significantly to the ultimate disposition of glucose carbon. Surprisingly, less than 50% of the acetyl-CoA pool was derived from blood-borne glucose, suggesting that additional substrates contribute to tumor bioenergetics. This study illustrates a convenient approach that capitalizes on the high information content of 13C NMR spectroscopy and enables the analysis of intermediary metabolism in diverse malignancies growing in their native microenvironment. PMID:22419606

  11. 12C/13C ratio in ethane on titan and implications for methane's replenishment.

    PubMed

    Jennings, Donald E; Romani, Paul N; Bjoraker, Gordon L; Sada, Pedro V; Nixon, Conor A; Lunsford, Allen W; Boyle, Robert J; Hesman, Brigette E; McCabe, George H

    2009-10-22

    The (12)C/(13)C abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(-1) from high spectral resolution ground-based observations. The value, 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The (12)C/(13)C ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(1), representing an enrichment of (12)C in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same (12)C/(13)C ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.

  12. [Characterization of biochar by X-ray photoelectron spectroscopy and 13C nuclear magnetic resonance].

    PubMed

    Xu, Dong-yu; Jin, Jie; Yan, Yu; Han, Lan-fang; Kang, Ming-jie; Wang, Zi-ying; Zhao, Ye; Sun, Ke

    2014-12-01

    The wood (willow branch) and grass (rice straw) materials were pyrolyzed at different temperatures (300, 450 and 600 °C) to obtain the biochars used in the present study. The biochars were characterized using elementary analysis, X-ray photoelectron spectroscopy (XPS) and solid state 13C cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy (13C NMR) to illuminate the structure and composition of the biochars which were derived from the different thermal temperatures and biomass. The results showed that the H/C, O/C and (O+N)/C ratios of the biochars decreased with the increase in the pyrolysis temperatures. The surface polarity and ash content of the grass-derived biochars were higher than those of the wood-derived biochars. The minerals of the wood-derived biochars were mainly covered by the organic matter; in contrast, parts of the mineral surfaces of the grass-derived biochars were not covered by organic matter? The 13C NMR of the low temperature-derived biochars revealed a large contribution of aromatic carbon, aliphatic carbon, carboxyl and carbonyl carbon, while the high temperature-derived biochars contained a large amount of aromatic carbon. Moreover, the wood-derived biochars produced at low heat treatment temperatures contained more lignin residues than grass-derived ones, probably due to the existence of high lignin content in the feedstock soures of wood-derived biochars. The results of the study would be useful for environmental application of biochars.

  13. Methanogenic capabilities of ANME-archaea deduced from (13) C-labelling approaches.

    PubMed

    Bertram, Sebastian; Blumenberg, Martin; Michaelis, Walter; Siegert, Michael; Krüger, Martin; Seifert, Richard

    2013-08-01

    Anaerobic methanotrophic archaea (ANME) are ubiquitous in marine sediments where sulfate dependent anaerobic oxidation of methane (AOM) occurs. Despite considerable progress in the understanding of AOM, physiological details are still widely unresolved. We investigated two distinct microbial mat samples from the Black Sea that were dominated by either ANME-1 or ANME-2. The (13) C lipid stable isotope probing (SIP) method using labelled substances, namely methane, bicarbonate, acetate, and methanol, was applied, and the substrate-dependent methanogenic capabilities were tested. Our data provide strong evidence for a versatile physiology of both, ANME-1 and ANME-2. Considerable methane production rates (MPRs) from CO2 -reduction were observed, particularly from ANME-2 dominated samples and in the presence of methane, which supports the hypothesis of a co-occurrence of methanotrophy and methanogenesis in the AOM systems (AOM/MPR up to 2:1). The experiments also revealed strong methylotrophic capabilities through (13) C-assimilation from labelled methanol, which was independent of the presence of methane. Additionally, high MPRs from methanol were detected in both of the mat samples. As demonstrated by the (13) C-uptake into lipids, ANME-1 was found to thrive also under methane free conditions. Finally, C35 -isoprenoid hydrocarbons were identified as new lipid biomarkers for ANME-1, most likely functioning as a hydrogen sink during methanogenesis.

  14. Temperature-mediated changes in microbial carbon use efficiency and 13C discrimination

    NASA Astrophysics Data System (ADS)

    Lehmeier, Christoph A.; Ballantyne, Ford, IV; Min, Kyungjin; Billings, Sharon A.

    2016-06-01

    Understanding how carbon dioxide (CO2) flux from ecosystems feeds back to climate warming depends in part on our ability to quantify the efficiency with which microorganisms convert organic carbon (C) into either biomass or CO2. Quantifying ecosystem-level respiratory CO2 losses often also requires assumptions about stable C isotope fractionations associated with the microbial transformation of organic substrates. However, the diversity of organic substrates' δ13C and the challenges of measuring microbial C use efficiency (CUE) in their natural environment fundamentally limit our ability to project ecosystem C budgets in a warming climate. Here, we quantify the effect of temperature on C fluxes during metabolic transformations of cellobiose, a common microbial substrate, by a cosmopolitan microorganism growing at a constant rate. Biomass C specific respiration rate increased by 250 % between 13 and 26.5 °C, decreasing CUE from 77 to 56 %. Biomass C specific respiration rate was positively correlated with an increase in respiratory 13C discrimination from 4.4 to 6.7 ‰ across the same temperature range. This first demonstration of a direct link between temperature, microbial CUE, and associated isotope fluxes provides a critical step towards understanding δ13C of respired CO2 at multiple scales, and towards a framework for predicting future ecosystem C fluxes.

  15. A Low Energy Measurement of the 13C(α,n) Reaction

    NASA Astrophysics Data System (ADS)

    Toomey, Rebecca; Febbraro, Michael; Pain, Steven; Cizewski, Jolie

    2016-09-01

    The slow neutron capture process (s process) is a key mechanism in heavy-element synthesis, reaching up to 209Bi. The s process creates elements along the line of beta-stability via neutron capture and beta decay in a low neutron flux environment in AGB stars. The dominant source of neutrons for the s process is the 13C(α,n) reaction. At the low energies occurring in these stellar conditions, this reaction cross section is very low, making direct measurement of the reaction rate difficult. Currently the state-of-the-art measurements using high-efficiency moderated neutron counter detectors have constrained this cross section down to approximately 300 keV - still well above stellar conditions, therefore requiring extrapolation of the S factor into the Gamow window ( 140-230 keV). This talk will focus on the motivation and preparation for low-energy measurements of the 13C(α,n) reaction using a neutron spectroscopic technique with the aim of reducing uncertainties in current measurements, and also attempt measurements at lower energies. Background measurements and the characterisation of the experimental set up from the measurement of 13C(α,n) at higher energies at the University of Notre Dame will be presented. This work is supported in part by the U.S. Department of Energy and National Science Foundation.

  16. Late Ordovician land plant spore 13C fractionation records atmospheric CO2 and climate change

    NASA Astrophysics Data System (ADS)

    Beerling, D. J.; Nelson, D. M.; Pearson, A.; Wellman, C.

    2008-12-01

    Molecular systematics and spore wall ultrastructure studies indicate that late Ordovician diad and triad fossil spores were likely produced by plants most closely related to liverworts. Here, we report the first δ13C estimates of Ordovician fossil land plant spores, which were obtained using a spooling wire micro-combustion device interfaced with an isotope-ratio mass spectrometer (Sessions et al., 2005, Analytical Chemistry, 77, 6519). The spores all originate from Saudi Arabia on the west of Gondwana and date to before (Cardadoc, ca. 460 Ma), during (443Ma) and after (Llandovery, ca. 440Ma) the Hirnantian glaciation. We use these numbers along with marine carbonate δ13C records to estimate atmospheric CO2 by implementing a theoretical model that captures the strong CO2-dependency of 13C fractionation in non-vascular land plants (Fletcher et al., 2008, Nature Geoscience, 1, 43). Although provisional at this stage, reconstructed CO2 changes are consistent with the Kump et al. (2008) (Paleo. Paleo. Paleo. 152, 173) 'weathering hypothesis' whereby pre-Hirnantian cooling is caused by relatively low CO2 (ca. 700ppm) related to enhanced weathering of young basaltic rocks during the early phase of the Taconic uplift, with background values subsequently rising to around double this value by the earliest Silurian. Further analyses will better constrain atmospheric CO2 change during the late Ordovician climatic perturbation and address controversial hypotheses concerning the causes and timing of the Earth system transition into an icehouse state.

  17. The use of 13-C-labelled polyaromatic hydrocarbons in soil bound residue formation

    SciTech Connect

    Richnow, H.H.; Seifert, R.; Hefter, J.

    1996-12-31

    The formation of non-extractable residues during biodegradation and humification processes in soils and sediments represent a major sink for organic contaminants. We studied the mode of incorporation of polycyclic aromatic hydrocarbons (PAM) and their metabolites into macromolecular organic matter during microbial degradation applying {sup 13}C-labelled compounds. Mineralization rates were determined by measuring the {sup 13}CO{sub 2} production. An incorporation of {sup 13}C-PAH-fragments into humic material could be traced by isotopic analysis of the bulk organic matter. Furthermore, selective chemical degradation reactions were applied to analyze the precise chemical structure of covalently bound {sup 13}C-labelled PAH fragments in soil humic substances. Structural assignments by GC-MS combined with isotope measurements on the bulk organic carbon and the molecular level (IRM-GC-MS) provide useful information on the fate of xenobiotics within the soil. The results are discussed in the context of long-term risk assessment of bioremediated soils.

  18. Optimization of 13C dynamic nuclear polarization: isotopic labeling of free radicals

    NASA Astrophysics Data System (ADS)

    Niedbalski, Peter; Parish, Christopher; Kiswandi, Andhika; Lumata, Lloyd

    Dynamic nuclear polarization (DNP) is a physics technique that amplifies the nuclear magnetic resonance (NMR) signals by transferring the high polarization of the electrons to the nuclear spins. Thus, the choice of free radical is crucial in DNP as it can directly affect the NMR signal enhancement levels, typically on the order of several thousand-fold in the liquid-state. In this study, we have investigated the efficiency of four variants of the well-known 4-oxo-TEMPO radical (normal 4-oxo-TEMPO plus its 15N-enriched and/or perdeuterated variants) for use in DNP of an important metabolic tracer [1-13C]acetate. Though the variants have significant differences in electron paramagnetic resonance (EPR) spectra, we have found that changing the composition of the TEMPO radical through deuteration or 15N doping yields no significant difference in 13C DNP efficiency at 3.35 T and 1.2 K. On the other hand, deuteration of the solvent causes a significant increase of 13C polarization that is consistent over all the 4-oxo-TEMPO variants. These findings are consistent with the thermal mixing model of DNP. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and the Robert A. Welch Foundation Grant No. AT-1877.

  19. Density functional theory study of (13)C NMR chemical shift of chlorinated compounds.

    PubMed

    Li, Songqing; Zhou, Wenfeng; Gao, Haixiang; Zhou, Zhiqiang

    2012-02-01

    The use of the standard density functional theory (DFT) leads to an overestimation of the paramagnetic contribution and underestimation of the shielding constants, especially for chlorinated carbon nuclei. For that reason, the predictions of chlorinated compounds often yield too high chemical shift values. In this study, the WC04 functional is shown to be capable of reducing the overestimation of the chemical shift of Cl-bonded carbons in standard DFT functionals and to show a good performance in the prediction of (13)C NMR chemical shifts of chlorinated organic compounds. The capability is attributed to the minimization of the contributions that intensively increase the chemical shift in the WC04. Extensive computations and analyses were performed to search for the optimal procedure for WC04. The B3LYP and mPW1PW91 standard functionals were also used to evaluate the performance. Through detailed comparisons between the basis set effects and the solvent effects on the results, the gas-phase GIAO/WC04/6-311+G(2d,p)//B3LYP/6-31+G(d,p) was found to be specifically suitable for the prediction of (13)C NMR chemical shifts of chlorides in both chlorinated and non-chlorinated carbons. Further tests with eight molecules in the probe set sufficiently confirmed that WC04 was undoubtedly effective for accurately predicting (13) C NMR chemical shifts of chlorinated organic compounds.

  20. Potential of δ13C in Pollen to Serve as Paleotemperature Proxy

    NASA Astrophysics Data System (ADS)

    King, D. P.; Foelber, K.; Schubert, B.; Jahren, A.

    2010-12-01

    Fossil pollen is an invaluable indicator of vegetation composition, is notably resilient against diagenetic alteration, and can be found in large quantities within highly chronologically-resolved substrates such as lake sediments. In addition, several recent isotopic techniques have made possible the analysis of small quantities (approaching <100 pollen grains) while nanomaterials hold promise for efficient shape-sorting of pollen assemblages. Because environmental conditions affect the stable isotope signature of plant tissues, we explored the potential for the δ13C value of pollen produced by plants growing under diverse climate regimes to reflect paleotemperature. We examined the relationship between temperature and δ13C of the pollen produced in several settings including: laboratory growth chambers, single-genus field comparisons, and whole-community comparisons from botanical gardens. In each of these settings the relationship between growing season temperature and the δ13C of pollen produced resulted in a positive correlation with R2 > 0.5; our presentation will discuss the practical implementation of stable isotopes in pollen as a paleotemperature proxy, both in terms of substrate recovery and produced-certainty of temperature estimates.

  1. SUMOFLUX: A Generalized Method for Targeted 13C Metabolic Flux Ratio Analysis

    PubMed Central

    Kogadeeva, Maria

    2016-01-01

    Metabolic fluxes are a cornerstone of cellular physiology that emerge from a complex interplay of enzymes, carriers, and nutrients. The experimental assessment of in vivo intracellular fluxes using stable isotopic tracers is essential if we are to understand metabolic function and regulation. Flux estimation based on 13C or 2H labeling relies on complex simulation and iterative fitting; processes that necessitate a level of expertise that ordinarily preclude the non-expert user. To overcome this, we have developed SUMOFLUX, a methodology that is broadly applicable to the targeted analysis of 13C-metabolic fluxes. By combining surrogate modeling and machine learning, we trained a predictor to specialize in estimating flux ratios from measurable 13C-data. SUMOFLUX targets specific flux features individually, which makes it fast, user-friendly, applicable to experimental design and robust in terms of experimental noise and exchange flux magnitude. Collectively, we predict that SUMOFLUX's properties realistically pave the way to high-throughput flux analyses. PMID:27626798

  2. Prediction of successive steps of SOM formation in aggregates and density fractions based on the 13C natural abundance

    NASA Astrophysics Data System (ADS)

    Gunina, Anna; Kuzyakov, Yakov

    2014-05-01

    Aggregate formation is a key process of soil development, which promotes carbon (C) stabilization by hindering decomposition of particulate organic matter (POM) and its interactions with mineral particles. C stabilization processes lead to 13C fractionation and consequently to various δ13C values of soil organic matter (SOM) fractions. Differences in δ13C within the aggregates and fractions may have two reasons: 1) preferential stabilization of organic compounds with light or heavy δ13C and/or 2) stabilization of organic materials after passing one or more microbial utilization cycles, leading to heavier δ13C in remaining C. We hypothesized that: 1) 13C enrichment between the SOM fractions corresponds to successive steps of SOM formation; 2) 13C fractionation (but not the δ13C signature) depends mainly on the transformation steps and not on the C precursors. Consequently, minimal differences between Δ13C of SOM fractions between various ecosystems correspond to maximal probability of the SOM formation pathways. We tested these hypotheses on three soils formed from cover loam during 45 years of growth of coniferous or deciduous forests or arable crops. Organic C pools in large macroaggregates, small macroaggregates, and microaggregates were fractionated sequentially for four density fractions to obtain free POM with ρ

  3. 13C-detected NMR experiments for measuring chemical shifts and coupling constants in nucleic acid bases.

    PubMed

    Fiala, Radovan; Sklenár, Vladimír

    2007-10-01

    The paper presents a set of two-dimensional experiments that utilize direct (13)C detection to provide proton-carbon, carbon-carbon and carbon-nitrogen correlations in the bases of nucleic acids. The set includes a (13)C-detected proton-carbon correlation experiment for the measurement of (13)C-(13)C couplings, the CaCb experiment for correlating two quaternary carbons, the HCaCb experiment for the (13)C-(13)C correlations in cases where one of the carbons has a proton attached, the HCC-TOCSY experiment for correlating a proton with a network of coupled carbons, and a (13)C-detected (13)C-(15)N correlation experiment for detecting the nitrogen nuclei that cannot be detected via protons. The IPAP procedure is used for extracting the carbon-carbon couplings and/or carbon decoupling in the direct dimension, while the S(3)E procedure is preferred in the indirect dimension of the carbon-nitrogen experiment to obtain the value of the coupling constant. The experiments supply accurate values of (13)C and (15)N chemical shifts and carbon-carbon and carbon-nitrogen coupling constants. These values can help to reveal structural features of nucleic acids either directly or via induced changes when the sample is dissolved in oriented media.

  4. Gastrointestinal handling of [1-13C]palmitic acid in healthy controls and patients with cystic fibrosis

    PubMed Central

    Murphy, J.; Jones, A.; Stolinski, M.; Wootton, S.

    1997-01-01

    Accepted 2 January 1997
 AIM—To examine the gastrointestinal handling of [1-13C]palmitic acid given as the free acid by measuring the excretion of 13C label in stool in 16 healthy children and 11 patients with cystic fibrosis on their habitual enzyme replacement treatment.
METHODS—After an overnight fast, each child ingested 10 mg/kg body weight [1-13C]palmitic acid with a standardised test meal of low natural 13C abundance. A stool sample was collected before the test and all stools were collected thereafter for a period of up to five days. The total enrichment of 13C in stool and the species bearing the 13C label was measured using isotope ratio mass spectrometry.
RESULTS—The proportion of administered 13C label excreted in stool was 24.0% (range 10.7-64.9%) in healthy children and only 4.4% (range 1.2-11.6%) in cystic fibrosis patients. The enrichment of 13C in stool was primarily restricted to the species consumed by the subjects (that is as palmitic acid).
CONCLUSION—There does not appear to be a specific defect in the absorption of [1-13C]palmitic acid in patients with cystic fibrosis. The reasons why cystic fibrosis patients appear to absorb more of this saturated fatty acid than healthy children is not clear and requires further investigation.

 PMID:9196358

  5. Temperature signal instability of tree-ring δ13C chronology in the northeastern Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Wenzhi; Liu, Xiaohong; Xu, Guobao; Zeng, Xiaomin; Wu, Guoju; Zhang, Xuanwen; Qin, Dahe

    2016-04-01

    Tree ring δ13C as a climate proxy is widely used for palaeoclimate research, however, its temporal stability response to the climate change remains unclear under more than one limited factors on tree growth. Here, we used a millennium tree-ring δ13C chronology combining two annual-resolution δ13C chronologies since 1800 from long-lived Qilian juniper (Sabina przewalskii) to assess its instability of the climate signal in the northeastern Qinghai-Tibetan Plateau. Tree-ring δ13C chronologies were strongly correlated with the regional mean April to August temperature from 1956 to 2008, but the associations were absent within the period 1901 to 1955 values in the CRU TS dataset. Comparison of the millennium-long δ13C series with reconstructed Asian temperatures also demonstrated that the δ13C chronology exhibited climate signal temporal instability. Substantial oscillations were revealed using a frequency-dependent analysis and 51-year running correlation analysis from the millennium-long tree-ring δ13C and δ18O series. Dual-isotope approach indicated that stomatal limitations created a statistical significant positive correlation between tree-ring δ13C and δ18O, but photosynthetic rate may be dominant when the correlations were not significant. Our results suggest that tree-ring δ13C series in the northeastern Qinghai-Tibetan Plateau is responded instability to temperature variations in the past 1000 years.

  6. Assessing microbial utilization of free versus sorbed Alanine by using position-specific 13C labeling and 13C-PLFA analysis

    NASA Astrophysics Data System (ADS)

    Herschbach, Jennifer; Apostel, Carolin; Spielvogel, Sandra; Kuzyakov, Yakov; Dippold, Michaela

    2016-04-01

    Microbial utilization is a key transformation process of soil organic matter (SOM). Sorption of low molecular weight organic substances (LMWOS) to soil mineral surfaces blocks or delays microbial uptake and therefore mineralization of LMWOS to CO2, as well as all other biochemical transformations. We used position-specific labeling, a tool of isotope applications novel to soil science, combined with 13C-phospholipid fatty acid (PLFA) analysis, to assess microbial utilization of sorbed and non-sorbed Alanine in soil. Alanine has various functional groups enabling different sorption mechanisms via its positive charge (e.g. to clay minerals by cation exchange), as well as via its negative charge (e.g. to iron oxides by ligand exchange). To assess changes in the transformation pathways caused by sorption, we added uniformly and position-specifically 13C and 14C labeled Alanine to the Ap of a loamy Luvisol in a short-term (10 days) incubation experiment. To allow for sorption of the tracer solution to an aliquot of this soil, microbial activity was minimized in this subsample by sterilizing the soil by γ-radiation. After shaking, the remaining solutions were filtered and the non-sorbed Alanine was removed with Millipore water and then added to non-sterilized soil. For the free Alanine treatment, solutions with Alanine of similar amount and isotopic composition were prepared, added to the soil and incubated as well. The respired CO2 was trapped in NaOH and its 14C-activity was determined at increasing times intervals. Microbial utilization of Alanine's individual C positions was evaluated in distinct microbial groups classified by 13C-PLFA analysis. Sorption to soil minerals delayed respiration to CO2 and reduced initial respiration rate by 80%. Irrespective of sorption, the highest amount was respired from the carboxylic position (C-1), whereas the amino-bound (C-2) and the methylic position (C-3) were preferentially incorporated into PLFA of microorganisms due to the

  7. Using Position-Specific 13C and 14C Labeling and 13C-PLFA Analysis to Assess Microbial Transformations of Free Versus Sorbed Alanine

    NASA Astrophysics Data System (ADS)

    Apostel, C.; Herschbach, J.; Bore, E. K.; Kuzyakov, Y.; Dippold, M. A.

    2015-12-01

    Sorption of charged or partially charged low molecular weight organic substances (LMWOS) to soil mineral surfaces delays microbial uptake and therefore mineralization of LMWOS to CO2, as well as all other biochemical transformations. We used position-specific labeling, a tool of isotope applications novel to soil sciences, to compare the transformation mechanisms of sorbed and non-sorbed alanine in soil. Alanine as an amino acid links C- and N-cycles in soil and therefore is a model substance for the pool of LMWOS. To assess transformations of sorbed alanine, we added position-specific and uniformly 13C and 14C labeled alanine tracer to soil that had previously been sterilized by γ-radiation. The labeled soil was added to non-sterilized soil from the same site and incubated. Soil labeled with the same tracers without previous sorption was prepared and incubated as well. We captured the respired CO2 and determined its 14C-activity at increasing time intervals. The incorporation of 14C into microbial biomass was determined by chloroform fumigation extraction (CFE), and utilization of individual C positions by distinct microbial groups was evaluated by 13C-phospholipid fatty acid analysis (PLFA). A dual peak in the respired CO2 revealed two sorption mechanisms. To compare the fate of individual C atoms independent of their concentration and pool size in soil, we applied the divergence index (DI). The DI reveals the convergent or divergent behavior of C from individual molecule positions during microbial utilization. Alanine C-1 position was mainly oxidized to CO2, while its C-2 and C-3 were preferentially incorporated in microbial biomass and PLFA. This indicates that sorption by the COOH group does not protect this group from preferential oxidation. Microbial metabolism was determinative for the preferential oxidation of individual molecule positions. The use of position-specific labeling revealed mechanisms and kinetics of microbial utilization of sorbed and non

  8. A comparison of substrate oxidation during prolonged exercise in men at terrestrial altitude and normobaric normoxia following the coingestion of 13C glucose and 13C fructose.

    PubMed

    O'Hara, John P; Woods, David R; Mellor, Adrian; Boos, Christopher; Gallagher, Liam; Tsakirides, Costas; Arjomandkhah, Nicola C; Holdsworth, David A; Cooke, Carlton B; Morrison, Douglas J; Preston, Thomas; King, Roderick Fgj

    2017-01-01

    This study compared the effects of coingesting glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at altitude and sea level, in men. Seven male British military personnel completed two bouts of cycling at the same relative workload (55% Wmax) for 120 min on acute exposure to altitude (3375 m) and at sea level (~113 m). In each trial, participants ingested 1.2 g·min(-1) of glucose (enriched with (13)C glucose) and 0.6 g·min(-1) of fructose (enriched with (13)C fructose) directly before and every 15 min during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation, and endogenous glucose oxidation derived from liver and muscle glycogen. Total carbohydrate oxidation during the exercise period was lower at altitude (157.7 ± 56.3 g) than sea level (286.5 ± 56.2 g, P = 0.006, ES = 2.28), whereas fat oxidation was higher at altitude (75.5 ± 26.8 g) than sea level (42.5 ± 21.3 g, P = 0.024, ES = 1.23). Peak exogenous carbohydrate oxidation was lower at altitude (1.13 ± 0.2 g·min(-1)) than sea level (1.42 ± 0.16 g·min(-1), P = 0.034, ES = 1.33). There were no differences in rates, or absolute and relative contributions of plasma or liver glucose oxidation between conditions during the second hour of exercise. However, absolute and relative contributions of muscle glycogen during the second hour were lower at altitude (29.3 ± 28.9 g, 16.6 ± 15.2%) than sea level (78.7 ± 5.2 g (P = 0.008, ES = 1.71), 37.7 ± 13.0% (P = 0.016, ES = 1.45). Acute exposure to altitude reduces the reliance on muscle glycogen and increases fat oxidation during prolonged cycling in men compared with sea level.

  9. Enhancing Phospholipid Fatty Acid Profiling of Soil Bacterial Communities via Substrate- Specific 13C-labelling

    NASA Astrophysics Data System (ADS)

    Evershed, R. P.; Maxfield, P. J.; Bingham, E. M.; Dildar, N.; Brennand, E. L.; Hornibrook, E.

    2008-12-01

    A range of culture-independent methods, has recently emerged to study environmental microorganisms in situ[1]. One such method is phospholipid fatty acid (PLFA) analysis, wherein these ubiquitous membrane lipids provide a powerful tool for the study of unculturable soil microorganisms. PLFA analyses have been used to investigate the impacts of a wide range of environmental factors on the soil microbial community. An acknowledged shortcoming of the PLFAs approach is the lack the chemotaxonoic specificity, which restricts the ability of the method to probe the activities of specific functional groups of the microbial community selectively. However, the selectivity of PLFAs analyses can be enhanced by incubating soils with 13C- labelled substrates followed by gas chromatography-combustion-isotope ratio mass spectrometry to reveal the specific PLFAs incorporating the 13C-label. The application of this approach will be demonstrated through our recent work on methanotrophic bacteria in soils. We applied this approach initially to mineral soils[2] and then extended chemotaxonomic assessments by using a combination of 13C-labelled PLFAs and hopanoids [3]. We have used this approach to explore the properties of high affinity methanotrophs in a range of environments, investigating the relationship between methane oxidation rates and the nature and magnitude of the methanotrophic community for the first time[4,5] More recently we extended the technique using a novel time series 13C-labelling of PLFAs[6] to estimate the rate and progression of 13C- label incorporation and turnover of methanotrophic populations. This modified approach has been used to investigate the impacts of various environmental variables, e.g. soil type, vegetation cover and land use, on the methanotrophic biomass[7.8]. The unique nature of the 13CH4 as a gaseous substate/carbon source means that can be readily introduced into soils via a specific subset of the soil microbial biomass, thereby offering many

  10. δ13C Degassing Dynamics of a Young Volcanic Center, Cerro Negro, Nicaragua

    NASA Astrophysics Data System (ADS)

    Lucic, G.; Stix, J.; Wing, B. A.; Muñoz, A.; Ibarra, M.; Sherwood Lollar, B.; Lacrampe-Couloume, G.

    2011-12-01

    Measurement of gas-phase δ13C values above active volcanic centers has the potential for monitoring magma dynamics associated with degassing and recharge events above subduction zones. The strong isotopic partitioning between C in the gas and melt, and C isotopic differences among magmas enables degassed CO2 to give insight into processes happening deep underground. Cerro Negro volcano in Nicaragua is an ideal center for detecting such magma interactions due to its rich history of volcanic activity and unusual eruption style. It is a subduction-driven, basaltic cinder cone that erupts on average once every 20 years with light to moderate intensity explosive eruptions (Volcanic Explosivity Index: 1-3) commonly accompanied by lava flows. Amid these eruptions are periods of extreme quiescence with very little seismic activity and gas emissions, suggesting rapid magmatic changes beneath the volcano. The brief lag time (on average 30 min). separating precursors and eruption supports this interpretation. In this study, we compare the isotopic composition of gas samples collected from fumaroles, fractures and other thermal areas on the volcano over a period of nearly 2 decades (1992-2011) in order to constrain the magmatic evolution beneath Cerro Negro. While the general systematics of the entire dataset are broadly consistent with degassing models for the natural evolution of CO2 and δ13C values, recent sampling campaigns suggest that new magma may be entering the system. Gases collected in January 2011 after 12 years of quiescence reveal CO2 concentrations ranging from 1-100%, with δ13C values varying from -1.5% to -10.4% with a mean of -3.3±0.28 % for 32 samples. Only limited spatial variability is present in this dataset: inner crater mean δ13C = -4.0±0.12 %, outer crater (-2.4±0.46 %), flanks (-4.4±0.26 %), and thermal areas to the N (-3.5±0.24 %) and SE (-2.5±0.25 %). Based on previous work, a lack of substantial spatial variation in δ values is

  11. Hyperfine structure in the J = 1-0 transitions of DCO^+, DNC, and HN13C: astronomical observations and quantum-chemical calculations

    NASA Astrophysics Data System (ADS)

    van der Tak, F. F. S.; Müller, H. S. P.; Harding, M. E.; Gauss, J.

    2009-11-01

    Context: Knowledge of the hyperfine structure of molecular lines is useful for estimating reliable column densities from observed emission, and essential for the derivation of kinematic information from line profiles. Aims: Deuterium bearing molecules are especially useful in this regard, because they are good probes of the physical and chemical structure of molecular cloud cores on the verge of star formation. However, the necessary spectroscopic data are often missing, especially for molecules which are too unstable for laboratory study. Methods: We have observed the ground-state (J = 1{-}0) rotational transitions of DCO^+, HN13C and DNC with the IRAM 30 m telescope toward the dark cloud LDN 1512 which has exceptionally narrow lines permitting hyperfine splitting to be resolved in part. The measured splittings of 50-300 kHz are used to derive nuclear quadrupole and spin-rotation parameters for these species. The measurements are supplemented by high-level quantum-chemical calculations using coupled-cluster techniques and large atomic-orbital basis sets. Results: We find eQq = + 151.12 (400) kHz and CI = -1.12 (43) kHz for DCO^+, eQq = 272.5 (51) kHz for HN13C, and eQq(D) =265.9 (83) kHz and eQq(N) = 288.2 (71) kHz for DNC. The numbers for DNC are consistent with previous laboratory data, while our constants for DCO+ are somewhat smaller than previous results based on astronomical data. For both DCO+ and DNC, our results are more accurate than previous determinations. Our results are in good agreement with the corresponding best theoretical estimates, which amount to eQq = 156.0 kHz and CI = -0.69 kHz for DCO^+, eQq = 279.5 kHz for HN13C, and eQq(D) = 257.6 kHz and eQq(N) = 309.6 kHz for DNC. We also derive updated rotational constants for HN13C: B = 43 545.6000 (47) MHz and D = 93.7 (20) kHz. Conclusions: The hyperfine splittings of the DCO^+, DNC and HN13C J = 1{-}0 lines range over 0.47-1.28 km s-1, which is comparable to typical line widths in pre

  12. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    NASA Astrophysics Data System (ADS)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    Cross polarization (CP) magic angle spinning (MAS) 13C-NMR spectroscopy is a solid state NMR technique widely used to study chemical composition of organic materials with low or no solubility in the common deuterated solvents used to run liquid state NMR experiments. Based on the magnetization transfer from abundant nuclei (with spin of 1 -2) having a high gyromagnetic ratio (γ), such as protons, to the less abundant 13C nuclei with low γ values, 13C-CPMAS NMR spectroscopy is often applied in environmental chemistry to obtain quantitative information on the chemical composition of natural organic matter (NOM) (Conte et al., 2004), although its quantitative assessment is still matter of heavy debates. Many authors (Baldock et al., 1997; Conte et al., 1997, 2002; Dria et al., 2002; Kiem et al., 2000; Kögel-Knabner, 2000; Preston, 2001), reported that the application of appropriate instrument setup as well as the use of special pulse sequences and correct spectra elaboration may provide signal intensities that are directly proportional to the amount of nuclei creating a NMR signal. However, many other papers dealt with the quantitative unsuitability of 13C-CPMAS NMR spectroscopy. Among those, Mao et al. (2000), Smernik and Oades (2000 a,b), and Preston (2001) reported that cross-polarized NMR techniques may fail in a complete excitation of the 13C nuclei. In fact, the amount of observable carbons via 13C-CPMAS NMR spectroscopy appeared, in many cases, lower than that measured by a direct observation of the 13C nuclei. As a consequence, cross-polarized NMR techniques may provide spectra where signal distribution may not be representative of the quantitative distribution of the different natural organic matter components. Cross-polarization is obtained after application of an initial 90° x pulse on protons and a further spin lock pulse (along the y axis) having a fixed length (contact time) for both nuclei (1H and 13C) once the Hartmann-Hahn condition is matched

  13. Physical and biogeochemical correlates of spatio-temporal variation in the δ13C of marine macroalgae

    NASA Astrophysics Data System (ADS)

    Mackey, Andrew P.; Hyndes, Glenn A.; Carvalho, Matheus C.; Eyre, Bradley D.

    2015-05-01

    Carbon isotope ratios (13C/12C) can be used to trace sources of production supporting food chains, as δ13C undergoes relatively small and predictable increases (∼0.5‰) through each trophic level. However, for this technique to be precise, variation in δ13C signatures of different sources of production (baseline sources) must be clearly defined and distinct from each other. Despite this, δ13C in the primary producers of marine systems are highly variable over space and time, due to the complexity of physical and biogeochemical processes that drive δ13C variation at the base of these foodwebs. We measured spatial and temporal variation in the δ13C of two species of macroalgae that are important dietary components of grazers over temperate reefs: the small kelp Ecklonia radiata, and the red alga Plocamium preissianum, and related any variation to a suite of physical and biogeochemical variables. Patterns in δ13C variation, over different spatial (10 s m to 100 km) and temporal scales (weeks to seasons), differed greatly between taxa, but these were partly explained by the δ13C of dissolved inorganic carbon (DIC) and light. However, while the δ13C in E. radiata was not related to water temperature, a highly significant proportion of the spatio-temporal variation in δ13C of P. preissianum was explained by temperature alone. Accordingly, we applied this relationship to project (across temperate Australasia) and forecast (in time, south-western Australia) patterns in P. preissianum δ13C. The mean projected δ13C for P. preissianum in the study region varied by only ∼1‰ over a 12-month period, compared to ∼3‰ over 2000 km. This illustrates the potential scale in the shift of δ13C in baseline food sources over broad scales, and its implications to food web studies. While we show that those relationships differ across taxonomic groups, we recommend developing models to explain variability in δ13C of other baseline sources to facilitate the

  14. Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    NASA Astrophysics Data System (ADS)

    Alexandre, A.; Balesdent, J.; Cazevieille, P.; Chevassus-Rosset, C.; Signoret, P.; Mazur, J.-C.; Harutyunyan, A.; Doelsch, E.; Basile-Doelsch, I.; Miche, H.; Santos, G. M.

    2015-12-01

    In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5 % of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13 % of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15 % of the

  15. Specific 13C functional pathways as diagnostic targets in gastroenterology breath-tests: tricks for a correct interpretation.

    PubMed

    Pizzoferrato, M; Del Zompo, F; Mangiola, F; Lopetuso, L R; Petito, V; Cammarota, G; Gasbarrini, A; Scaldaferri, F

    2013-01-01

    Breath tests are non-invasive, non-radioactive, safe, simple and effective tests able to determine significant metabolic alterations due to specific diseases or lack of specific enzymes. Carbon isotope (13)C, the stable-non radioactive isotope of carbon, is the most used substrate in breath testing, in which (13)C/(12)C ratio is measured and expressed as a delta value, a differences between readings and a fixed standard. (13)C/(12)C ratio is measured with isotope ratio mass spectrometry or non-dispersive isotope-selective infrared spectrometer and generally there is a good agreement between these techniques in the isotope ratio estimation. (13)C/(12)C ratio can be expressed as static measurement (like delta over baseline in urea breath test) or as dynamic measurement as percent dose recovery, but more dosages are necessary. (13)C Breath-tests are involved in many fields of interest within gastroenterology, such as detection of Helicobacter pylori infection, study of gastric emptying, assessment of liver and exocrine pancreatic functions, determination of oro-caecal transit time, evaluation of absorption and to a lesser extend detection of bacterial overgrowth. The use of every single test in a clinical setting is vary depending on accuracy and substrate costs. This review is meant to present (13)C the meaning of (13)C/(12)C ratio and static and dynamic measure and, finally, the instruments dedicated to its use in gastroenterology. A brief presentation of (13)C breath tests in gastroenterology is also provided.

  16. Hyperpolarized 13C NMR lifetimes in the liquid-state: relating structures and T1 relaxation times

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Hashami, Zohreh; Fidelino, Leila; Kovacs, Zoltan; Lumata, Lloyd

    Among the various attempts to solve the insensitivity problem in nuclear magnetic resonance (NMR), the physics-based technique dissolution dynamic nuclear polarization (DNP) is probably the most successful method of hyperpolarization or amplifying NMR signals. Using this technique, liquid-state NMR signal enhancements of several thousand-fold are expected for low-gamma nuclei such as carbon-13. The lifetimes of these hyperpolarized 13C NMR signals are directly related to their 13C spin-lattice relaxation times T1. Depending upon the 13C isotopic location, the lifetimes of hyperpolarized 13C compounds can range from a few seconds to minutes. In this study, we have investigated the hyperpolarized 13C NMR lifetimes of several 13C compounds with various chemical structures from glucose, acetate, citric acid, naphthalene to tetramethylallene and their deuterated analogs at 9.4 T and 25 deg C. Our results show that the 13C T1s of these compounds can range from a few seconds to more than 60 s at this field. Correlations between the chemical structures and T1 relaxation times will be discussed and corresponding implications of these results on 13C DNP experiments will be revealed. US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  17. 13C-NMR relation study of heparin-disaccharide interactions with tripeptides GRG and GKG.

    PubMed Central

    Mikhailov, D; Mayo, K H; Pervin, A; Linhardt, R J

    1996-01-01

    Heparin is a polydisperse sulphated copolymer consisting mostly of 1-->4 linked glucosamine and uronic acid residues, i.e. 2-deoxy-2-sulphamido-D-glucopyranose 6-sulphate and L-idopyranosyluronic acid 2-sulphate. 13C NMR has been used to study the interactions of heparinase-derived and purified heparin disaccharide with N- and C-terminally-blocked tripeptides GRG and GKG. Titration of the disaccharide with peptide indicates that GRG binds the disaccharide more strongly than does GKG, with interactions in either case being stronger at uronate ring positions. In the presence of GRG, a carboxylate pKa depression suggests electrostatic interactions between the arginine guanidinium group and the uronate carboxylate group. 13C relaxation data have been acquired for all disaccharide and peptide carbons in the presence and absence of GRG and GKG. 13C relaxation rates for the disaccharide are significantly faster in the presence of peptide, especially with GRG. Analysis of these relaxation data has been done in terms of molecular diffusion constants, D [symbol: see text] and D parallel, and an angle alpha between D parallel and a molecular frame defined by the moment of inertia tensor calculated for an internally rigid disaccharide. Disaccharide conformational space in these calculations has been sampled for both uronate half-chair forms (2H1 and 1H2) and over a range of glycosidic bond angles defined by motional order parameters and inter-residue nuclear Overhauser effects (+/- 30 degree from the average). In the absence of peptide, the ratio D [symbol: see text] /D parallel falls between 0.4 and 0.7; therefore molecular diffusion occurs preferentially about D parallel, which runs through both disaccharide rings. In the presence of peptide, D [symbol: see text] /D parallel is decreased, indicating that GRG is oriented along D parallel and proximal to the uronic acid ring. A model for this is shown. PMID:8615813

  18. Regulatory issues on breath tests and updates of recent advances on [13C]-breath tests.

    PubMed

    Modak, Anil S

    2013-09-01

    Over the last decade non invasive diagnostic phenotype [(13)C]-breath tests as well as tests using endogenous volatile organic compounds (VOCs) in breath have been researched extensively. However, only three breath tests have been approved by the FDA over the last 15 years. Despite the potential benefits of these companion diagnostic tests (CDx) for evaluation of drug metabolizing enzyme activities and standalone diagnostic tests for disease diagnosis to personalize medicine, the clinical and commercial development of breath tests will need to overcome a number of regulatory, financial and scientific hurdles prior to their acceptance into routine clinical practice. The regulatory agencies (FDA and EMEA) need to adapt and harmonize their approval process for companion diagnostic tests as well as standalone diagnostic breath tests for personalized medicine. The Center for Devices and Radiological Health has deemed any breath test that involves a labeled (13)C substrate/drug and a device requires a Pre Market Approval (PMA), which is analogous to an approved New Drug Application. A PMA is in effect, a private license granted to the applicant for marketing a particular medical device. Any breath test with endogenous VOCs along with a device can be approved via the 510(k) application. A number of (13)C breath tests with clinical applications have been researched recently and results have been published in reputed journals. Diagnostic companies will need to invest the necessary financial resources to develop and get regulatory approval for diagnostic breath tests capable of identifying responders/non responders for FDA approved drugs with narrow therapeutic indices (personalized medicine) or for evaluating the activity of drug metabolizing P450 polymorphic enzymes or for diagnosing diseases at an early stage or for monitoring the efficacy of medications. The financial success of these diagnostic breath tests will then depend entirely on how the test is marketed to

  19. Tracking the flow of bacterially derived 13C and 15N through soil faunal feeding channels.

    PubMed

    Crotty, F V; Blackshaw, R P; Murray, P J

    2011-06-15

    The soil food web has been referred to as a 'black box', a 'poor man's tropical rainforest' and an 'enigma', due to its opacity, diversity and the limited insight into feeding specificity. Here we investigate the flow of C and N through the soil food web as a way to gain understanding of the feeding interactions occurring. A bacterium, Pseudomonas lurida, was introduced to soil cores from two different habitats, a grassland and a woodland with the same soil type, enriched to 99 atom% in (13)C and (15)N, to trace the flow of bacterial C and N through the soil food web. Throughout the experiment the soil remained enriched in (13)C and (15)N. Almost all the invertebrates tested gained C and N enrichment indicative of the labelled bacteria, implying that bacterial feeding is a common mechanism within the soil. Only three groups were significantly enriched in both (13)C and (15)N in both habitats. These were Collembola (Entomobryomorpha), Acari (Oribatida), and Nematoda, indicating that these organisms are consuming the most bacteria within both systems. When the invertebrates were grouped into hypothesised trophic levels, those considered secondary decomposers were gaining the most enrichment across all invertebrates tested. This enrichment was also high in the micro-predators within the soil, implying that their main food source was the secondary decomposers, particularly the Collembola. Using an enriched bacterium to track the trophic transfer between organisms within the soil food web is a novel way of empirically showing that interactions are occurring, which normally cannot be seen.

  20. Microhabitat effects on Cd/Ca and δ 13C of benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Tachikawa, K.; Elderfield, H.

    2002-09-01

    Cd/Ca and δ 13C were measured on bottom and pore water samples, and samples comprising dead individuals of six species of benthic foraminifera, including Cibicidoides wuellerstorfi, Uvigerina peregrina and Melonis barleeanum, from throughout the sediment mixed layer at three well-characterised sites in the Northeastern Atlantic. 'Living' (i.e., Rose Bengal stained) U. peregrina and M. barleeanum from one of the three sites were also analysed. Co-existing living and dead foraminifera of the same species from the same site have similar Cd/Ca and δ 13C, and show no significant down core variability. Therefore, comparison of δ 13C in foraminifera with bottom water and pore waters was used to estimate average calcification depths within the sediment for each species and thereby determine DCd based on the Cd concentrations at these depths. Pore waters are 2-4 times more enriched in Cd than bottom waters; consequently, DCd values are different from estimates based on bottom water Cd. Results give DCd of ˜1 for all the infaunal species, with no significant water depth dependence. DCd for C. wuellerstorfi based on bottom water Cd are 3.2±1.1 at 3600 m water depth and 3.9±1.3 at 1900 m water depth, being consistent with DCd estimated from culture experiments. The results suggest that the depth dependence of DCd based on bottom water Cd may be partly explained by a pore water influence on the test chemistry for infaunal species.

  1. Enrichment in 13C of atmospheric CH4 during the Younger Dryas termination

    NASA Astrophysics Data System (ADS)

    Melton, J. R.; Schaefer, H.; Whiticar, M. J.

    2012-07-01

    The abrupt warming across the Younger Dryas termination (~11 600 yr before present) was marked by a large increase in the global atmospheric methane mixing ratio. The debate over sources responsible for the rise in methane centers on the roles of global wetlands, marine gas hydrates, and thermokarst lakes. We present a new, higher-precision methane stable carbon isotope ratio (δ13CH4) dataset from ice sampled at Påkitsoq, Greenland that shows distinct 13C-enrichment associated with this rise. We investigate the validity of this finding in face of known anomalous methane concentrations that occur at Påkitsoq. Comparison with previously published datasets to determine the robustness of our results indicates a similar trend in ice from both an Antarctic ice core and previously published Påkitsoq data measured using four different extraction and analytical techniques. The δ13CH4 trend suggests that 13C-enriched CH4 sources played an important role in the concentration increase. In a first attempt at quantifying the various contributions from our data, we apply a methane triple mass balance of stable carbon and hydrogen isotope ratios and radiocarbon. The mass balance results suggest biomass burning (42-66% of total methane flux increase) and thermokarst lakes (27-59%) as the dominant contributing sources. Given the high uncertainty and low temporal resolution of the 14CH4 dataset used in the triple mass balance, we also performed a mass balance test using just δ13C and δD. These results further support biomass burning as a dominant source, but do not allow distinguishing of thermokarst lake contributions from boreal wetlands, aerobic plant methane, or termites. Our results in both mass balance tests do not suggest as large a role for tropical wetlands or marine gas hydrates as commonly proposed.

  2. Line Positions and Intensities for the ν12 Band of 13C12CH_6

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Crawford, Timothy J.; Mantz, Arlan; Smith, Mary Ann H.

    2014-06-01

    High-resolution, high signal-to-noise spectra of mono-substituted 13C-ethane (13C12CH_6) in the 12.2 μm region were recorded with a Bruker IFS 125HR Fourier transform spectrometer. The spectra were obtained for four sample pressures at three different temperatures between 130 and 208 K using a 99% 13C-enriched ethane sample contained in a 20.38-cm long coolable absorption cell. A multispectrum nonlinear least squares fitting technique was used to fit the same intervals in the four spectra simultaneously to determine line positions and intensities. Similar to our previous analyses of 12C_2H_6 spectra in this same region, constraints were applied to accurately fit each pair of doublet components arising