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Showing 1 to 20 of 31 for “"17O"”.
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Electroexcitation of the giant resonance of 17O
The 11 to 30 MeV excitation region of 17O has been investigated by means of inelastic electron scattering, with special emphasis placed on the giant resonance. The scattering angle employed was 75.1°, and the incident energies were 64.9, 83.3, 101.3, 113.6, and 124.0 MeV. These conditions …
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The (p,n) reaction on 9Be and 17O at 135 MeV
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1985.
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Solid-State 17O NMR as a New Probe to Study Acyl-Enzyme Intermediates
This thesis reports on a combined solid-state 17O NMR and quantum mechanical study of three acyl-enzyme intermediates: p-N,N-dimethylaminobenzoyl-chymotrypsin (DAB-CHT), trans¬¬-¬o-methoxycinnamoyl-chymotrypsin (oMC-CHT), and trans-p-methoxycinnamoyl-chymotrypsin (pMC-CHT). At pH 7.8, the three …
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Use Of 17o-Nmr Spectroscopy To Study The Coordination Chemistry Of Trivalent Lanthanide Ions In Solution
… solvent molecules coordinated to Dy3+ ions using 17O-NMR spectroscopy in acetone, ethyl acetate, tetrahydrofuran, dimethylsulfonate, dimethylformaldehyde, di-isopropyl ketone, hexamethyl acetone and 4-chlorobenzaldehyde. These solvents were selected because they contain a range of functional …
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Large contribution of light-dependent oxygen uptake to global O2 cycling
The oxygen triple-isotope composition (Δ′17O = δ′17O - θ × δ′18O) of tropospheric O2 is an important parameter used in mass-balance proxy estimates of gross oxygen productivity in the modern ocean and the global biosphere. We created a chemical reaction network box model of the Δ′17O budget of …
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ΜΕΛΕΤΗ ΤΗΣ ΔΙΑΜΟΡΦΩΣΗΣ ΚΑΙ ΤΗΣ ΜΟΡΙΑΚΗΣ ΔΥΝΑΜΙΚΗΣ ΤΩΝ ΕΓΚΕΦΑΛΙΝΩΝ ΜΕ ΦΑΣΜΑΤΟΣΚΟΠΙΑ ΠΥΡΗΝΙΚΟΥ ΜΑΓΝΗΤΙΚΟΥ ΣΥΝΤΟΝΙΣΜΟΥ (17Ο-NMR) ΚΑΙ ΥΠΕΡΥΘΡΟΥ...
IN THIS STUDY THE RESULTS OF 17O-NMR STUDIES OF LEU-ENKEPHALIN SELECTIVELY ENRICHED IN 17O IN POSITIONS GLY-2, GLY-3 AND THE TERMINAL CARBOXYL GROUP ARE REPORTED. FROM STUDIES IN AQUEOUS SOLUTIONS AND IN CH3CH/DMSO (4:1) MIXTURES, IN SEVERAL PH AND TEMPERATURE VALUES IT IS CONCLUDED THAT BOTH …
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Structural studies on Functional Materials using Solid-State NMR, Powder X-ray Diffraction and DFT Calculations
… materials. One and two dimensional 31P and 17O solid state NMR experiments highlight subtle thermally induced structural changes in (MoO2)2P2O7 pyrophosphate, tungsten trioxide WO3 and negative thermal expansion ZrW2O8. DFT methods using CASTEP software to calculate 31P and 17O NMR …
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Concentration and isotopic composition of marine nitrous oxide, in particular the oxygen-17 isotope excess
The oxygen isotope excess Δ(17O) is a potential tracer of biological nitrous oxide (N2O) cycling. This study presents the first measurements of Δ(17O) in marine N2O together with details about the design and development of a custom-built Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-IRMS) …
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Solid-State NMR of Metallic and Paramagnetic Systems
… following studies have been performed: 1) The 17O NMR of Sm2O3, Eu2O3 and Sm/Eu-substituted CeO2, for which the lanthanide ions induce paramagnetic shifts with unusual temperature dependences due to the presence of low-lying excited electronic states. The spectra of the monoclinic polymorphs of …
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Low-nuclearity titanium alkoxides and their rhodium derivatives
… of Ti(OPri)4 with 0.078 equiv. of 10 atom% 17O enriched water and 0.6 equiv. of MeOH in i-PrOH solution gave [Ti3O](OPr i)9(OMe) (1). A single crystal X-ray diffraction study of this material indicated that 1 contains two crystallographically-independent Ti3(mu3-O)(mu3-OMe)(mu2-OPr …
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Nuclear magnetic resonance study of the bonding of carbon monoxide to palladium and platinum surfaces
The 13c and 17o NMR of CO chemisorbed on small particles of Pd and Pt has been observed. The 17o resonance represents the first reported NMR observation of a spin larger than 1/2 adsorbed on a metal surface. At low temperatures, the 13c resonance of CO on Pd is centered at 540 ppm down field from …
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Constraining air-sea equilibrium and biological end-members for marine gross productivity estimates using oxygen triple isotopes
… 2000). This approach exploits the relative 17O/16O and 18O/16O isotope ratio differences of dissolved O2 compared to atmospheric O2 to work out the rate of biological production. Two parameters are key for this calculation: the isotopic composition of dissolved O2 in equilibrium with air and …
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Investigation of the Oxygen Isotope Exchange Between Carbon Dioxide and O3 via O(1D)
… with altitude which preferential enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, but details of the mechanism are not understood yet. A systematic study was carried out using O2 …
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Triple oxygen isotope measurements by tunable infrared laser direct absorption spectroscopy, and applications to ratite eggshell
… with previously reported values. In addition, Δ'17O 1σ reproducibilities of 10, 19, and 60 per meg (1 per meg = 0.001‰) of these standards, respectively, are achieved. Analysis of RES suggests notable environmental differences between the central and southern Namib through time. RES D' 17O signal …
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An NMR Spectroscopy and Density-Functional Theory Study of Organometallic Complexes and Heme Proteins With Carbonyl, Alkylisocyanide, Nitrosoarene and Olefin Ligands: Applications to Structure Determinations
… shift and shift anisotropy as well as the 17O chemical shift, and the 17O nuclear quadrupole coupling constant (NQCC) lead to most probable ligand tilt (tau) and bend (beta) angles of 0°,l° for the Ao-substate when using a Bayesian probability or Z-surface method for structure …
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Alteration mechanisms of spent nuclear fuel and characterization of potential uranium secondary phases.
… Raman spectroscopy with a chapter dedicated on 17O NMR. For the latter, given the long alteration timeline for uranium dioxide, it is challenging to achieve sufficient alteration products for analysis within a short 4-year PhD program. Some known uranium compounds were synthesized and enriched …
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Production of C, N and O fragments in the interaction of 12C with 12C at an incident energy of 200 MeV.
… the spectra. The fragments heavier than 17O are almost entirely produced as evaporation residues.
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Water Transport in the Vadose Zone and Hydrological Processes in Soil-Plant-Atmosphere Continuum (SPAC) in West Texas, USA
… is isotopically depleted. In addition, the high 17O-excess record in atmospheric vapor in the summer of 2022 resulted from the intense evaporation fractionation of the preceding precipitation. Soil water monitoring and HYDRUS simulations show that typical rainfall events in summer 2022 can hardly …
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Symmetry Specific Study of Ozone Isotopomer Formation
… All atmospherically relevant, i.e. the simply 17O or 18O substituted ozone isotopomers could thereby be quantified. Precision in the measurement of the isotope abundance was improved to 0.3%. Systematic errors in earlier investigations were identified and minimized in the present measurements. …
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Multinuclear Solid-State Nuclear Magnetic Resonance Spectroscopy of Microporous Materials
… also thoroughly investigated by 1H, 2H, 13C, 17O, and 25Mg SSNMR. A comprehensive study of titanosilicates by 29Si, 23Na, 39K, and 47/49Ti SSNMR was also performed. This work is highlighted by the acquisition of natural abundance SSNMR spectra for three unreceptive quadrupolar nuclei, 47/49Ti …
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