Oxygen radioactive isotopes

Although the radioactive isotope H has been extensively used for studies on the uptake of xenobiotics into whole cells, the intrusion of exchange reactions and the large isotope effect renders this isotope rather less straightforward for metabolic studies. Both deuterium H-labeled substrates, and oxygen and OH2 have, however, been extensively used in metabolic studies, since essentially pure labeled compounds are readily available and mass spectrometer facilities have become an essential part of structural determination. 

The most important use of barium is as a scavenger in electronic tubes. The metal, often in powder form or as an alloy with aluminum, is employed to remove the last traces of gases from vacuum and television picture tubes. Alloys of barium have numerous applications. It is incorporated to lead alloy grids of acid batteries for better performance and added to molten steel and metals in deoxidizing alloys to lower the oxygen content. Thin films of barium are used as lubricant suitable at high temperatures on the rotors of anodes in vacuum X-ray tubes and on alloys used for spark plugs. A few radioactive isotopes of this element find applications in nuclear reactions and spectrometry. 

Indeed, this happens every moment in the Earth s atmosphere. The upper atmosphere is bombarded with cosmic rays fast-moving subatomic particles produced by extremely energetic astrophysical processes such as nuclear fusion in the sun. When cosmic rays hit molecules in the atmosphere, they induce nuclear reactions that spit out neutrons. Some of these neutrons react with nitrogen atoms in air, converting them into a radioactive isotope of carbon carbon-14 or radiocarbon , with eight neutrons in each nucleus. This carbon reacts with oxygen to form carbon dioxide. About one in every million million carbon atoms in atmospheric carbon dioxide is C. 

Recently Peterson and Wiley discussed the non-stoichiometry ofCuj- O, based on their measurement of the diffusion coefficient of Cu (radioactive isotope of Cu) in Cu2 5O as a function of temperature and oxygen partial pressure, Here let us review the results in some detail. 

Potassium has two stable isotopes (39K and 41K) and one naturally occurring radioactive isotope (4°K). Thelast, via its decay, accounts for the high abundance of 40 Ar in the Earth s atmosphere. It also provides a valuable means of dating ancient rocks. Potassium nucleosynthesis derives almost entirely from a single main-line source, the fusion of oxygen in massive stars that will become Type II supernovae. 

All uranium isotopes, for example, have unstable nuclei. They are called radioactive isotopes, or radioisotopes for short. Many isotopes are not radioisotopes. Oxygen s three naturally occurring isotopes, for example, are stable. In contrast, chemists have successfully synthesized ten other isotopes of oxygen, all of which are unstable radioisotopes. (What products result when radioisotopes decay You will find out in Chapter 4.)... 

Normal pentane oxidation was also the subject of an investigation by Cullis and Hirschler [189] with respect to the formation of 1- and 2-pentene, and the effect of their addition to pentane + oxygen mixtures. Mechanisms of reaction were interpreted from radioactive isotope tracer studies by addition of substituted pentenes to the reactants [189], albeit under conditions involving appreciable temperature change. In an earlier study, Chung and Sandler [26] showed that the proportion of pentenes formed during pentane oxidation in a flow system reached a maximum at a reactor temperature of about 750 K. 

Ten radioactive isotopes of oxygen are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. 

Radioactive isotopes are often used as tracers to follow the path of an element through a chemical reaction. For example, using radiotracers chemists have determined that the oxygen atoms in O2 that are produced by a green plant during photosynthesis come from the oxygen in water and not the oxygen in carbon dioxide. 

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