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Showing 1 to 20 of 54 for “"15 N"”.
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Natural abundance of ¹⁵N as a tool for assessing patterns of nitrogen loss from forest ecosystems
… contrasting nitrate loss patterns, the [delta]15 N of soil and plant material should be higher at sites with higher nitrate losses. An underlying assumption in natural abundance isotope studies is that soil [delta]15 N is at steady-state over time. I found that [delta]15 N was not at steady …
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Development and application of isotopically-selective assays for nitric oxide metabolites.
… of nitric oxide. Use of L-arginine with a [15]N stable label allows determination of the NO pathway throughput, but requires sensitive detection methods which are capable of isotopic discrimination. The Griess assay for nitrite has been combined with surface enhanced resonance Raman …
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An investigation of the pathway of nitrogen incorporation into the leaf and root metabolism of Helianthus annuus L
… feeding levels has been investigated using 15 N - nitrate feeding>enzyme inhibitor studies ~nd enzymological assays. Excised leaves received feeding solutions at two · -3 · -3 concentrational levels: 300 ~g N cm and 50 µg N cm via the xylem stream prior to experimentation. Nitrate - 15 N …
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Community composition, migration and trophic positions of micronekton in two biogeochemical provinces of the South West Indian Ocean
… Since particulate organic matter had high δ 15 N values in the ISSG province, copepods were chosen as baseline in trophic level estimations. Feeding regime and size were shown to influence the trophic position of micronekon. In the ISSG, carnivores (fishes and squids) and omnivores …
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NMR as a probe for molecular adsorption on metal surfaces in electrochemical environments and at electrified interfaces
The $\sp{13}$C and $\sp{15}$N NMR spectra of surface adsorbed cyanide on a platinum electrode have been obtained for the first time. The in situ electrostatic field effect on $\sp{13}$C and $\sp{15}$N chemical shifts and the temperature effect on their relaxation times over a wide temperature range …
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Characterization of Denitrification and Leaching Losses of Fertilizer Nitrogen From Soil (Evolution, Isotope, Nitrous Oxide, Dinitrogen)
… errors in measuring denitrification by use of ('15)N-tracer techniques recently developed for determination of N(,2) and N(,2)O evolved from soil; (2) evaluate three methods of estimating fertilizer N loss under field conditions (grain yield reductions, an ('15)N difference method, and a direct …
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Role of N in Controlling Kernel Growth in Maize
… stem infused at silking with 240 mg of N, or 15 g of sucrose, or a combination of both (N + sucrose). Control plants were stem-infused with 0.05 mM ethylenediaminetetraacetic acid. To determine the recovery and subsequent distribution of N within the plant, N-deficient plants were also …
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Elucidating Structure and Dynamics of Extracellular Matrix Collagen Using Solid-State NMR
… in technology. The combination of $^13$C, $^15$N-labelled amino acid enrichment of in-vitro or in-vivo materials with two-dimensional solid-state NMR spectroscopy potentially provides a more detailed understanding of the complex collagen structure and dynamics at atomic resolution. …
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Multinuclear magnetic resonance studies of proteins
… in proteins was extended to $\sp{13}$C and $\sp{15}$N chemical shifts in proteins. Using quantum ab initio method, we refined and improved the reproduction of these chemical shifts from known protein structures. The chemical shifts from C$\sp\alpha,$ C$\sp\beta,$ C$\sp\prime$ and backbone amide …
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Structure Elucidation and Biosynthesis of Selected Bioactive Marine Natural Products (Bromophenols, Aplysina, Fistularis, Kelletia)
… was demonstrated for the first time. Also, {('15)N,('14)C}phenylalanine was shown to be a precursor of the former metabolite, thus providing evidence for the intermediacy of oximes in the conversion of amino acids to other sponge metabolites of biological interest. A biosynthetic pathway …
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Recovery of Nitrogen-15-Labeled Liquid Anhydrous Ammonia Applied to Soil
… the lack of proper isotopic concentrations of ('15)N-labeled LAA required to carry out such research. Quantitative techniques for LAA application on a laboratory scale have also been difficult.
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Synthesis, Structure, and Reactivity of osmium(VI) Nitrido, Imido, and Oxo Complexes
… 12, (Os(O)$\sb2$(CH$\sb2$SiMe$\sb3$)$\sb2$), 15 (n $>$ 2) and 16 (n = 1 and 2), and Os(O)$\sb2$(CH$\sb2$CPhMe$\sb2$)$\sb2$, 17, are discussed in Chapter 5. The reactivity of compounds 12, 15, 16 and 17 towards electrophiles such as py$\cdot$HBr, py$\cdot$HCl, and Me$\sb3$SiCl is reported. …
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Separation of the E2 and M1 form factors of the 6.32 MeV state of nitrogen-15 using (electron,electron'gamma)
The 6.32 MeV (${3\over 2}\sp-$) state of $\sp{15}$N was studied by coincident (e,e$\sp\prime\gamma$) electron scattering. The two transverse multipole form factors (E2 and M1) were separated using a combined analysis of (e,e$\sp\prime$) and (e,e$\sp\prime\gamma$) data. This experiment is the first …
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Emissões de CO2 , particionamento da respiração e qualidade da matéria orgânica em solos sob cultivo de eucalipto no Cerrado
… de plantas de eucalipto enriquecido com 13 C e 15 N para avaliação das alterações da composição molecular via 13 C e 15 N NMR multiple cross polarization (MultCP). As maiores emissões de CO 2 foram encontradas na época chuvosa, sendo que o eucalipto apresentou menores fluxos que a mata nativa na …
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Chemical synthesis of isotopically labelled (M+4) purine nucleosides and their incorporation into DNA oligomers
… very sensitive to the purity of the commercial [15]N benzylamine reagent. Having failed, after several attempts, to obtain the pure reagent from commercial suppliers, [15]N benzylamine was successfully synthesised in our laboratory and used in the first synthesis of (M+4) guanine. Although (M+4) …
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Diet Assessment in Tropical African Populations - the implications of detecting biological signals in current diets to the study of past diets
… 83), and breath (n = 186) for δ$^{13}$C and δ$^{15}$N from the six different communities, and dental moulds (n = 150) from five of those communities (no moulds were collected from the Baka), and related the findings to dietary information. Dental microwear analyses had a low success rate because …
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I SYNTHESES OF SELECTIVELY FUNCTIONALIZED 9(ANE)NITROGEN(3) AND 12(ANE)NITROGEN(3) CYCLIC TRIAMINES II SYNTHESES, COMPLEXATION, AND CONFORMATIONAL STUDIES OF SOME AZAPODANDOCORONANDS (TRANSANNULAR, TRICYCLICORTHOAMIDE, AMIDINIUM SALTS)
… to these compounds (IR, ('1)H NMR, ('13)C NMR, ('15)N NMR, DNMR) are discussed in terms of relevant stereoelectronic effects and transannular interactions. The synthetic methodology by which these compounds provide routes to selectively protected cyclic triamines is discussed relative to the …
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Ab initio calculations of NMR chemical shifts for structure determination in biology
… depends mainly on the secondary structure and 15-N NMR chemical shift depends mainly on hydrogen bonds. The importance of other relevant contributions to the chemical shifts, such as solvent and dynamical effects, is demonstrated by testing our computational method on proteins and by comparing …
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INVESTIGATING THE CONTRIBUTION OF MARINE VIRUSES TO OPTICAL BACKSCATTER IN THE <0.2 µM FRACTION OF SEAWATER
… cruise over a latitudinal transect from 15°N to 35°N at 26°W from the euphotic zone and in three areas of the Gulf of Mexico (Petit Bois, Horn Island, Cat Island). Samples were subjected to two size fractionations (0.2 µm, and 30 kDa) where marine viruses are assumed present in thefor 0.2 …
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Implementing Prediabetes Screening During Hospitalization In An Internal Medicine Unit
… The rate of undiagnosed T2DM and prediabetes was 15% (n=6) and 36% (n=15), respectively. Implementation of patient education occurred in 52% (n=11) of patients, while 76% (n=16) had primary care follow-up arranged. Though limited by a small sample size, utilization of the prediabetes screening …
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