Nitrogen isotopic

The half-lives of the elements vary widely, as shown in Table 3.2. Some isotopes, nitrogen-14 for example, are stable and experience no natural radioactive decay. However, bombarding even a stable element with energetic alpha rays can cause transmutation. Rutherford discovered the proton when he created hydrogen from a stable isotope of nitrogen. 

Nitrogen is one of the main components of the amino acids the weight ratio between its stable isotopes, nitrogen-15 and nitrogen-14 reflects the nature of... 

Burris, R.H. Distribution of isotopic nitrogen in Azotobacter vindandii. J. Biol. Chem. 143, 509-517 (1942). 

Two other reactions have been examined and will be discussed briefly. One is the exchange of isotopic nitrogen,... 

Studies on the photolysis of simple aliphatic and alicyclic nitrites have confirmed the need for a six-membered transition state, which decides the point of attack on a carbon chain [ 18]. The photolysis of a nitrite (9) gives an active alkoxy radical and a molecule of nitric oxide, which is itself a stable free radical. These radicals must at first be confined within a solvent cage (lo), for no significant scrambling of isotopic nitrogen occurred when a mixture of the nitrite (14) and... 

The formation of the mixed-isotope nitrogen molecule was found to be first-order in N2 and first-order in the diluent gas, Ar, thus ruling out as the ratedetermining step, the bimolecular reaction of two nitrogen molecules. The second-order rate coefficient for the reaction is given by... 

Nitrogen is a non-metallic element located in group 15 of the periodic table. It has two stable isotopes nitrogen-14, with an abundance of 99.634%, and nitrogen-15, with an abundance of 0.366%. At least five radioactive isotopes of the element have been prepared, with atomic weights of 12, 13, 16, 17, and 18. 

P5. Plentl, A. A., and Schoenheimer, R., Studies in metabolism of purines and pyrimidines by means of isotopic nitrogen. J. Biol. Chem. 163, 203-217 (1944). 

Stable heavy isotope nitrogen ( N) is determined using either mass spectrometry or emission spectrometry (Fiedler and Proksch 1975, Hauck 1982). Radioactive is measured by direct emission measurements or by liquid scintillation methods (Tiedje 1981). 

KROHN AND MATHIS Isotopic Nitrogen as a Biochemical Tracer 235... 

Keywords stable isotopes, nitrogen, organic matter, palaeolimnology, C/N, mass spectrometry... 

The approach Is tested by considering the relative vapor pressures of three Isotopic molecules. One finds for the isotopic nitrogens and N N . 

In addition to being a small neutral molecule, urea has a considerable advantage over uric acid as a terminal product of nitrogen metabolism in that it is much more soluble. As has been the case for many other pathways in intermediary metabolism, the understanding of ureas biosynthesis began with the availability of isotopic nitrogen and carbon. The administration of [ NJammonium salt and " C-labeled bicarbonate salt demonstrated that urea nitrogen derives from ammonia and urea carbon from respiratory CO2. 

Before 1934, the study of radioactivity was limited to reactions of the relatively few radioisotopes found in nature. In that year, Irene and Frederic Joliot-Curie, French physical chemists, found that radioactivity could be induced in nonradioactive nuclei by bombarding them with small, subatomic particles. They produced an artificial radioactive isotope, nitrogen-13, by bombarding boron-10 with alpha particles from a natural radioisotope ... 

Nitrogen has two naturally occurring isotopes nitrogen-14 (mass = 14.00 amu) and nitrogen-15 (mass = 15.00 amu). Bromine also has two naturally occurring isotopes bromine-79 (mass = 78.92 amu) and bromine-81 (mass = 80.92 amu). How many NBr3 molecules of different masses can exist Determine the mass (in amu) of each of them. 

D. Relative Vapor Pressures of Isotopic Nitrogens, Carbon... 

Equation (1-4 ) is very well obeyed by the vapor pressures of isotopic nitrogens where the experimental values of the vapor pressures show that... 

This notation shows the isotope nitrogen-14 reacting with a neutron, n, giving off a proton, p, and forming the carbon-14 isotope other nuclear reactions can be deduced from this notation where x represents nuclear fragments from spallation. 

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