Radiation induced radioactivity

Medieval alchemists spent years trying to convert other metals into gold without success. Years of failure and the acceptance of Dalton s atomic theory early in the nineteenth century convinced scientists that one element could not be converted into another. Then, in 1896 Henri Becquerel discovered radioactive rays (natural radioactivity) coming from a uranium compound. Ernest Rutherford s study of these rays showed that atoms of one element may indeed be converted into atoms of other elements by spontaneous nuclear disintegrations. Many years later it was shown that nuclear reactions initiated by bombardment of nuclei with accelerated subatomic particles or other nuclei can also transform one element into another—accompanied by the release of radiation (induced radioactivity). 

Activation Process of inducing radioactivity in a material by bombardment with other types of radiation, such as neutrons. 

Radioactivity. Methods based on the measurement of radioactivity belong to the realm of radiochemistry and may involve measurement of the intensity of the radiation from a naturally radioactive material measurement of induced radioactivity arising from exposure of the sample under investigation to a neutron source (activation analysis) or the application of what is known as the isotope dilution technique. 

Pohl-Ruling, J. and P. Fischer, Chromosome Aberrations in Inhabitants of Areas With ELevated Natural Radioactivity, in Radiation-Induced Chromosome Damage in Man (T. Ishihara and M.S. Sasaki, ed) pp. 527-560, A.R. Liss, Inc., New York (1982). 

Various other radiation-induced reactions have been studied for potential use in the industry on a pilot-plant scale. Among these may be mentioned hydrocarbon cracking (i.e., production of lower-molecular-weight hydrocarbons from higher-molecular-weight material), isomerization of organic molecules, and synthesis of labeled compounds with radioactive nuclei. When organic compounds are irradiated in the pure state or in aqueous solution, dimeric... 

Following intravenous injection of Thorotrast in humans and animals, various malignancies were found, primarily liver cancers (latency period of 25-30 years), leukemia (latency period of 20 years), and bone cancers (latency period of about 26 years). Short-lived daughter products of thorium also resulted in the induction of bone sarcoma because of their short radioactive half-lives. Intravenous injection of thorium-228 resulted in dose-dependent induction of bone sarcoma in dogs (Lloyd et al. 1985 Mays et al. 1987 Stover 1981 Wrenn et al. 1986). At the highest administered level, the animals died from systemic radiological effects (e.g., radiation induced blood dyscrasia and nephritis) before the bone sarcoma could develop (Stover 1981 Taylor et al. 1966). A relationship was found between the amount of thorium-227 (half-life of 18.7 days) injected intraperitoneally and the incidence of bone sarcoma in mice (Luz et al. 1985 Muller et al. 1978). 

There are three significant possible effects when radiation interacts with matter (5,6). First, the radiation can interact with the nucleus and induce radioactivity as in the case of neutrons. Second, displacement of atoms can occur. This has happened in a number of uranium- and thorium-containing minerals over geological periods. The outstanding example is zircon, which can contain over 10% Th and 2% U. The internal bombardment from these materials and their decay products over geological periods produces low or metamict zircon, where the disorder gives an amorphous state having a low density. 

Reactions of atomic carbon, produced by nuclear reactions, with a number of hydrocarbons have been studied by Wolfgang and his collaborators (69). To minimize radiation induced secondary reactions which occur when use is made of C14, a technique has been developed using short-lived C11 produced by a neutron exchange reaction between a platinum foil and a C12 ion beam from a heavy ion accelerator. Part of the scattered Cu atoms has been allowed to penetrate through the thin brass foil wall of a brass vessel and come in contact with the compound wrhose reaction is studied. Products have been analyzed by gas chromatography using a technique of simultaneous mass and radioactivity determination. 

Radiation beams induce radioactivity primarily by photonuclear reactions. In these reactions, the absorption of energy from the incident electron, x-ray, or 7-ray will produce an excited nucleus that will then emit a neutron, proton, triton, 7-ray, or other secondary radiation. The chart of the nuclides from carbon to sodium in Figure 1 demonstrates the type of nuclide resulting from the emission of a secondary radiation from a given parent nuclide (10). The threshold energies necessary for the incoming radiation to produce a secondary radiation are given for a few of the reactions most relevant to this report. 

In 1954, the book by Professor B.N. Tarusov "Principles of Biological Effects of Radioactive Emissions" was published [1] the book made a great impression on me. The author, an outstanding Soviet biophysicist. Head of the Biophysics Department at the Faculty of Biology of the Moscow State University, put forward a hypothesis that the development of radiation-induced disease is associated with the induction of ramified chain reaction of oxidation of fats of cellular shells (membranes), the oxidation products are very toxic for the cell. 

On the other hand, natural radioactivity has been noticeable throughout evolution, and radiation-induced damages are usually efficient triggers of DNA repair. 

By far the most important application of tritium is its use as a radioactive tracer in extensive labeling studies. The production of tritium-labeled organic compounds was greatly enhanced with the discovery that tritium could be introduced to a compound merely by storing that compound under tritium gas for a few days or weeks the radiation induces exchange... 

All absolute dating methods that have proven dependable are based on radioactive decay. Virtually all of the methods depend on the methodical decrease in the amount of the radioactive nuclide and the growth of the corresponding daughter product. The one exception is in the area of radiation-induced damage in solids, which is the basis of thermoluminescence or ESR dating. This latter scheme will be dealt with later in the chapter. Here the basic principles of canonical radioactive geochronometry as applied to marine deposits is reviewed. 

There is no evidence to date of any increase in the incidence of any malignancies other than thyroid carcinoma or of any hereditary effects attributable to radiation exposure caused by the Chernobyl accident. This conclusion, surprising for some observers, is in accordance with the relatively small whole body doses incurred by the populations exposed to the radioactive material released. The lifetime doses expected to be incurred by these populations are also small. In fact, the risks of radiation-induced malignancies and hereditary effects are extremely small at low radiation doses and, as the normal incidences of these effects in people are relatively high, it is not surprising that no effects could be detected. 

This technique is used to determine the concentration of an element by inducing radioactivity in one or more isotopes by nuclear particle bombardment. It can be used as a nondestructive method, but in a multi-component sample, separation may be necessary to eliminate the effect of overlapping spectral lines. The method is similar in principle to other instrumental procedures that use energy sources to irradiate a substance to produce emission of characteristic radiation. 

Hypothyroidism is a relative deficiency in thyroid hormones. It manifests as a slowing down of all body functions or a decrease in metabolic rate. There are many causes for hypothyroidism, including Hashimoto s thyroiditis, drug-induced, radiation and radioactive iodine, dyshormono-genesis, congenital, and secondary causes (pituitary or... 

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