Nitrogen tracer studies with

It is best obtained by interaction of stoichiometric quantities of NO and 02 or NO and N204. It is an intensely blue liquid (f.p. ca. —100°) and a very pale blue solid. The oxide is formally the anhydride of nitrous acid, and dissolution of an equimolar mixture of NO and N02 in alkalis gives virtually pure nitrite. Nitrogen tracer studies have shown rapid exchange between NO and N02 consistent with the above equilibrium. The solid is believed to have two forms, an unstable one of structure ONONO and the other with a long N—N bond similar to that in N204 discussed below. 

Using a high quality emissions dataset, TAPM performance is very good for the prediction of extreme pollution statistics, important for environmental impact assessments, for both non-reactive (tracer) and reactive (nitrogen dioxide, ozone and particulate) pollutants for a variety of sources (e.g. industrial stacks and surface or urban emissions) - see Luhar and Hurley (2003) Hurley et al. (2005). A study with the attention to detail that makes a big difference, is by Luhar et al. (2006a). Other findings include ... 

The concepts that are emerging with respect to the pathways of nitrogen and carbon assimilation in soybean roots and nodules are summarized in Figure 14. The scheme that is shown is based in part on the tracer studies using short-lived isotopes reported here along with published and unpublished observations. The figure is intended to present... 

Nitrosyls.—A product characterization and N-tracer study of the reaction of rra/u-[RuCl(NO)(diars)2] with nitrogen bases, for example hydrazine, indicates nucleophilic attack at the nitrosyl-N. Similarly, the reaction of azide ion with [RuCl(NO)(bipy)2] is thought to involve attack at the nitrosyl-N. The rate law for this reaction is first order in each reactant. Varying degrees of nitrosyl-protonation are involved in the following reactions of metal nitrosyl compounds with hydrogen chloride ... 

JANSSON S.L. 1958. Tracer studies on nitrogen transformations in soil with special attention to mineralization-immobilization relationships. Annals of the Royal Agricultural College, Sweden, 24, 101-361. 

Tracer studies have shown that the isomerization of /ra/zj-[Co(en)2(NH3)-(SCN)] to the A-thiocyanato-linkage isomer in basic aqueous solution is intramolecular. The detailed mechanism may involve an intimate ion pair which does not exchange its thiocyanate with the thiocyanate in solution, a species in which the thiocyanate is Ji-bonded to the cobalt, or intramolecular attack of a deprotonated amine nitrogen at the thiocyanate carbon (Scheme 5). Aquation of [Co(NH3)5(sulphamate)] - is preceded by isomerization of the starting complex to an equilibrium mixture of N- and 0-bonded isomers. The specific rate constant for approach to equilibrium is l.lxlO s at 25 °C composite activation parameters are AH = 24.7 kcal mol and AS = 10.9 cal deg mol . Inability to estimate the equilibrium constant satisfactorily precludes the separation of these kinetic parameters into their forward and backward components. ... 

Early isotope tracer experiments by David Shemin permitted the elucidation of the formation of the immediate precursor of the porphyrin needed for the cytochromes and for hemoglobin. These studies indicated that the glycine methylene carbon and nitrogen were incorporated along with both carbons of acetate. Subsequent enzymatic studies in both bacteria and animals revealed a condensation reaction between succinyl-CoA and glycine to yield 5-amino-levulinate and C02 (presumably by way of an enzyme-bound /3-keto acid, a-amino-/3-ketoadipate) (fig. 22.13). 

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