Nitrogen radioactive, production

Whereas addition of hydrogen to feedwater helps solve the O2 or ECP problem, other complications develop. An increase in shutdown radiation levels and up to a fivefold increase in operating steam plant radiation levels result from the increased volatiUty of the short-Hved radioactive product nitrogen-16, N, (7.1 s half-life) formed from the coolant passing through the core. Without H2 addition, the in the fluid leaving the reactor core is in the form of nitric acid, HNO with H2 addition, the forms ammonia, NH, which is more volatile than HNO, and thus is carried over with the steam going to the turbine. 

After 1 s of assimilation of NH4% 77 (Anacystis nidulans) to 97% (C. licheniforme and A. cylindrica) of the in organic compounds extracted with methanol was associated with glutamine (Figure 7). In A. cylindrica, approximately 88% of the associated vsdth glutamine after 3 s of assimilation distilled as amide nitrogen (13). The second major radioactive product of assimilation of was glutamate in all... 

The isolated heterocysts also reduced [ N]N2 to radioactive products that could be steam-distilled in the presence of alkali from the methanolic extracts, with a fixation rate of up to 23% of the rate (per imit hetero-cysts/min) of intact filaments (Table III Reference J). When the suspension of isolated heterocysts was additionally supplemented with ImM glutamate, incubated for 120 s with [ N]N2 and the methanolic extracts subjected to sequential vacuum distillation at pH 10.0 and steam distillation in the presence of alkali, 66% of the fixed distilled as amide nitrogen and the remainder distilled as free ammonia (Table IV). The higher fraction of free in these experiments compared to... 

Unstable isotopes decompose (decay) by a process referred to as radioactivity. Ordinarily the result is the transmutation of elements the atomic number of the product nucleus differs from that of the reactant. For example, radioactive decay of produces a stable isotope of nitrogen, N. The radiation given off (Figure 2.6) may be in the form of—... 

In the carbon-14 expts, HMX/RDX product was isolated qualitatively, separated Into its components, and each component assayed for carbon-14 beta radioactivity using a liquid scintillation counting technique (Ref 11). DPT-l4C was isolated as an intermediate product from the reaction mixt and similarly radioassayed. For the nitrogen-15 tagged AN expts, HMX and RDX were assayed mass spectrometrically for i5N/i4N ratios from which atom %1SN contents were calcd. In die course of these expts, each tagged species was added initially and also at subsequent stages of the reaction process. The important observations and results are summarized as ... 

Ernest Rutherford was the first person to observe a binuclear reaction, hi 1919, he exposed a sample of nitrogen to a particles from a naturally radioactive source. He observed the production of protons and deduced from the requirements of charge and mass balance that the other product was oxygen-17 ... 

In order to clarify the possible existence of these intermediates, 6-chloro-5-cyano-4-phenyl[l(3)- N]pyrimidine (20) (the label is scrambled over both nitrogens) and the radioactive 6-chloro-5-[ " C-cyano]-4-phenylpyrimidine (23) were synthesized as substrates. Because of the presence of the cyano function at C-5, one can expect that 20 (and 23) would undergo amination involving an Sn(ANRORC) mechanism. This has indeed been found. When 20 was reacted with potassium amide in liquid ammonia, two products were obtained as main product, 6-amino-5-cyano-4-phenylpyrimidine (21, 75%), and as minor product, a-amino-jS,jS -dicyanostyrene (22, about 20%) (Scheme 11.15). 

Wolfe has presented an excellent description of the systematic application of stable and radioactive isotope tracers in determining the kinetics of urea production, urea recycling, and interorgan nitrogen transfer in living systems. 

Since the alpha-ray impacts shattered only a minute proportion of the total number of atoms of boron, aluminum, or magnesium, the chemical identification of the products was extremely difficult. These indefatigable workers, however, accomplished even this. Although it would have been impossible to identify the products simply by ordinary chemical means, the Joliots were able to take advantage of the radioactive nature of the products formed. Since they had good reason to believe that the boron atom had captured a helion and ejected a neutron and that the new element was therefore probably an isotope of nitrogen, they heated some bombarded boron nitride with caustic soda and found that the liberated... 

The new product, which they named radionitrogen, was a hitherto unknown radioactive isotope of ordinary nitrogen. It disintegrates with a half period of fourteen minutes and expulsion of positrons, forming a stable, inactive isotope of carbon ... 

After combustion of the sample and carriers in an oxygen stream, reducing conditions are achieved by a flow of carbon monoxide over the sample ash. Arsenic, zinc, cadmium, and any remaining selenium and mercury are reduced to elemental form. When the sample is heated to 1150°C in a slow carbon monoxide stream in a quartz tube in a furnace, recovery of all five elements in the liquid nitrogen trap is complete in 30 min. The recovery trap is washed with nitric acid to dissolve all the metals, and the radioactivity of a nitric acid solution of the products is counted with a Ge(Li) detector. 

The production of artificially produced radioactive elements dales back to the early work of Rutherford in 1919 when it was found that alpha particles reacted with nitrogen atoms to yield protons and oxygen atoms. Curie and Joliot found (1933) that when boron, magnesium, or aluminum were bombarded with alpha particles from polonium, the elements would emit neutrons, protons, and positrons. They also found that upon cessation... 

Radiocarbon dating of archaeological artifacts depends on the slow and constant production of radioactive carbon-14 in the upper atmosphere by neutron bombardment of nitrogen atoms. (The neutrons come from the bombardment of other atoms by cosmic rays.)... 

Owing to the possible production of radioactive isotopes, ozone, and oxides of nitrogen, the accelerator cell is equipped with an independent... 

The management of cancer includes treatment with alkylating agents (nitrogen mustards and alkyl sulfonates), antimetabolites (methotrexate and purine analogs), natural products (vinca alkaloids and antibiotics), miscellaneous compounds (hydroxyurea, procarbazine, and cis-platinum), hormones (estrogens and corticosteroids), and radioactive isotopes (see Chapter 62). 

One may rightfully raise the question as to why some products of nuclear reactions are radioactive while others are not. The answer concerns the stability of atomic nuclei. Essentially, any radioactive element, whether artificial or natural, can be considered abnormal. A nucleus that undergoes radioactive decay is in an unstable condition, and the process of decay always leads to stable isotopes. This tendency toward the achievement of stability is illustrated by the stepwise decay of naturally radioactive uranium to form a stable isotope of lead and the formation of stable carbon by the decay of artificial radioactive nitrogen. Although the conditions resulting in the instability of atomic nuclei are fairly well understood, further consideration of these factors is beyond the scope of this discussion. 

Tritium is also one of the products obtained by bombardment of fluorine, beryllium, antimony, copper, or silver with deuterons, or the bombardment of boron and nitrogen with neutrons. Tritium is the simplest known radioactive isotope. It decays by emission of beta particles to form an isotope of helium and has a half-life of about 12 years. 

The ethyl acetate extracts of the reaction mixture were concentrated under nitrogen and applied to 250p Silica Gel G plates (Analtech). The solvent used for the mobile phase was CHCl3-ethyl acetate (8 2). The plates were examined under an ultraviolet lamp and the bands were scraped clear into separate tubes. The products were then dissolved in ethyl acetate or n-butanol and analyzed by UV-visible spectrophotometry and the spectra from 254-450 nm were compared with those of authentic standards. Radioactivity levels were determined and the products were analyzed by mass spectrometry. 

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