Heavy nitrogen

In 1967 the scientists of the Joint Institute of Nuclear Research in Dubna, Russia, bombarded americium-243 with neon-22 to produce two isotopes of unnilpentium, then known as hahnium. The reaction is as follows jAm-243 + Ne-22 —> jjjjHahnium-260 and 261 (Unp-260 and 261). In 1970 Albert Ghiorso and his team at Berkeley bombarded califor-nium-249 with heavy nitrogen (N-15) in their Heavy Ion Linear Accelerator (HILAC). The reaction is as follows gCf-249 + -15 —> j jHa-260 (Unp-260). 

Das Sharma S, Patil DT, Gopalan K (2002) Temperature dependence of oxygen isotope fractionation of CO2 from magnesite-phosphoric acid reaction. Geochim Cosmochim Acta 66 589-593 Dauphas N, Marty B (1999) Heavy nitrogen in carbonatites of the Kola peninsula a possible signature of the deep mantle. Science 286 2488-2490 Dauphas N, Rouxel O (2006) Mass spectrometry and natural variations in iron isotopes. Mass Spectrom Rev 25 515-550... 

Apart from compound (I) an insignificant amount of product (II) is formed in which the heavy nitrogen occupies a different position C6H5—N=15N=N. 

A recent research by McGeer on the exchange reaction between light and heavy nitrogen on iron synthetic ammonia catalysis and on rhenium surfaces at 450° C provides a clue to such an attempt. The velocity of... 

Dauphas N. and Marty B. (1999) Heavy nitrogen in carbonatities of the Kola Peninsula a possible signature of the deep mantle. Science 286, 2488-2490. 

Fig. 8. Isotopic compositions of nitrogen and neon released from a lunar ilmenite separate subjected to stepwise etching by hydrofluoric acid. Close to grain surfaces, on the right of the plot, isotopically heavy nitrogen is associated with neon whose Ne/ Ne ratio equals that observed directly in the solar wind, whereas at greater depths within the grains, lighter nitrogen is associated with isotopically heavier neon, attributed by Wieler et al (1986) to solar energetic particles. From Mathew et al (1998).

How were the simple precursors of the pyrimidine ring recognized In 1943, Barnes and Schoenheimer showed that heavy nitrogen from N-ammonium citrate was incorporated into animal polynucleotides. It was apparent as early as 1944 that orotate (6-carboxyuracil) was involved in pyrimidine biosynthesis, because this compound would satisfy the pyrimidine requirement for some bacteria [see review (5)]. Between 1949 and 1952 it became apparent that orotate was probably an intermediate in pyrimidine biosynthesis because this compound was utilized efficiently in mammalian tissues as a precursor of both DNA and RNA p uimidines. However, the possibility remained that orotate per se w as not an actual intermediate, but rather was easily converted to one. 

Cells from tobacco callus tissue can be grown in liquid nutrient media as well as on solid. In a liquid medium the number of the cells doubles in about two days. Thus, in about two days the cells pass through one round of DNA synthesis. Now the cells were first maintained for several rounds of DNA synthesis in a medium with compounds containing heavy nitrogen, N. This leads to N being incorporated in the purine and pyrimidine bases of the DNA. Finally, all of the DNA is present as heavy DNA with N bases. This heavy DNA can be separated from normal DNA with N bases in a cesium chloride gradient in the ultracentrifuge. 

Similar experiments were carried out with plasma produced by administering to dogs the amino acid lysine synthesized with heavy nitrogen 50% of the labeled protein was found to have left the blood stream in about 24 hours 75% in about six days. Shock due to trauma of intestine or leg was found to show a dilution curve of labeled protein not ynlike that of the normal dog (49). 

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