Incorporation of radionuclides

Radioactive isotopes have been used since the mid-1940s for the elucidation of metabolic irregularities. Today, radionuchdes - principally H, and I - are used as tracers in all areas of pharmaceutical and biological research and in genetic technology [107]. In classical radio TLC, from the early 1960s, labeled prepared samples were applied to the TLC plate, which was then developed, and the p radiation was then measured with a TLC scaimer (raytest). 

in radio TLC the radioactive-labeled molecules are transported by the migrating solvent along the thin-layer trace and are finally stay at a certain point along the trace on the TLC. The radioactive fraction is distributed equally in the depth of the thin-layer material (silica gel) between the surface and bottom. 

Further information on radio TLC can be obtained from the company raytest (see Section 12.5). 

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Pereira, C., Hash, M. C., Lewis, M. A., Richmann, M. K. Basco, J. 1999. Incorporation of radionuclides from the electrometallurgical treatment of spent fuel into a ceramic waste form. Materials Research Society Symposium Proceedings, 556, 115-120. 

Traditionally the overall process of incorporation of radionuclides into plant tissues from contaminated soils via the root uptake process has been quantified using the soil-to-plant transfer factor, or TF. This is defined simply as the ratio of the specific radionuclide activities in the plant tissue of concern (usually some edible organ) and the soil, with the dry masses of each material usually being taken into account ... 

Thirdly, DNA was shown to be an important target using external radiation beams with very shallow penetration, or by intracellular incorporation of radionuclides with known penetration characteristics in nucleus or membrane. (Recently, considerable progress has been made in developing radiation beams with micron and sub-micron spatial resolution ( microbeams ), which are more sophisticated tools to probe sites of cellular radiosensitivity [75].)... 

Methylation is possible by the reaction of arylstannane with Mel. In order to find a general protocol for the synthesis of short-lived CH3-labeled PET (positron emission tomography) tracers for incorporation of radionuclides into bioactive organic compounds, Suzuki and co-workers carried out the coupling of Mel with tributylphenylstannane (24) to afford toluene as a model reaction in 91 % yield within 5 min. P(o-Tol)3 was used as a ligand, together with CuCl [25]. 

The dose in the environment - the delivered dose to a human body - depends on many factors, namely, on the spatial distribution of radionuclides (in soils or in the atmosphere), the characteristics of the radiation (energy, type, etc.), the living site of individuals (at sea level or high elevation, indoors or outdoors), including the incorporation of radionuclides into the body through inhalation and food intake. With high local variation, the worldwide average annual effective dose is about 4 mSv, nearly 3 mSv of it from natural sources and 1 mSv from artificial sources (O Table 47.6). 

In general, the results reported by different authors on the dependence of the deposition rates of corrosion product radionuclides on the nature of the pretreatment of the material surfaces do not show good agreement. Presumably, these discrepancies are due to differences in the details of the performance of the tests (e. g. pretreatment process, deposition testing) they reflect the fact that the essential details of the mechanisms of incorporation of radionuclides from the solution into the superficial oxide layers are not yet fully understood. On the other hand, the possibility cannot be ruled out that the nature of the superficial oxide layer plays only a minor role in the deposition of radionuclides from the solution. 

Other measures, such as chromium plating of the surfaces of the materials, which in experiments showed a beneficial effect in retarding the incorporation of radionuclides into the oxide layers have also been considered. As yet, however, no technical-scale application has been reported presumably, there are still technical questions to be solved. 

Incorporation of radionuclide in melt of glass with subsequent grinding... 

There are various parameters and assumptions defining radionuclide behavior that are frequently part of model descriptions that require constraints. While these must generally be determined for each particular site, laboratory experiments must also be conducted to further define the range of possibilities and the operation of particular mechanisms. These include the reversibility of adsorption, the relative rates of radionuclide leaching, the rates of irreversible incorporation of sorbed nuclides, and the rates of precipitation when concentrations are above Th or U mineral solubility limits. A key issue is whether the recoil rates of radionuclides can be clearly related to the release rates of Rn the models are most useful for providing precise values for parameters such as retardation factors, and many values rely on a reliable value for the recoil fluxes, and this is always obtained from Rn groundwater activities. These values are only as well constrained as this assumption, which therefore must be bolstered by clearer evidence. 

Muller, W.A., A.B. Murray, U. Linzner, and A. Luz. 1990. Osteosarcoma risk after simultaneous incorporation of the long-lived radionuclide 227Ac and the short-lived radionuclide 227Th. Radiation Res. 121 14-20. 

Recent years have also seen the development of a variety of com-plexation reagents incorporating C-P bonds and their associated functionalities, such as phosphoryl linkages. For example, substituted calixarenes (Figure 1.4) have been developed for extraction of radionuclides, and phosphorus-derivatized cyclodextrins for stereospecific inclusion interactions. 

The interaction and sorption of metal ions with metal oxide and clay surfaces has occupied the attention of chemists, soil scientists, and geochemists for decades (1-4). Transition metal oxides receiving particular emphasis have included various oxides of manganese and iron (5). Interest in sorption phenomena is promoted by the desire to better understand incorporation of metals into minerals, especially marine deposits ( ), the removal of trace metal pollutants and radionuclides from rivers and streams, via sorption and/or precipitation phenomena (1,6), and the deposition of metals on solid substrates in the preparation of catalysts (7,8). 

Luz A, Linzner U, Muller WA, et al. 1979. Osteosarcoma induction by simultaneous incorporation of Yh and inkc. Biological implications of radionuclides released from nuclear industries, Vol. 1. International Atomic Energy Agency, Vienna, 141-151. 

The ability of KI to block the thyroidal uptake of I and its incorporation into Tg would prove useful in the event of an accident at a nuclear power plant. In such an event, large quantities of radionuclides, including isotopes of radioiodine, could be released into the atmosphere. Administration of KI Thyro-Block) to inhibit the uptake and incorporation of radioiodine would be the most effective means of limiting the potential damage to the thyroid gland. 

The hosts for ACT and REE immobilization are phases with a fluorite-derived structure (cubic zirconia-based solid solutions, pyrochlore, zirco-nolite, murataite), and zircon. The REEs and minor ACTs may be incorporated in perovskite, monazite, apatite-britholite, and titanite. Perovskite and titanite are also hosts for Sr, whereas hollandite is a host phase for Cs and corrosion products. None of these ceramics is truly a single-phase material, and other phases such as silicates (pyroxene, nepheliiie, plagioclase), oxides (spinel, hibonite/loveringite, crichtonite), or phosphates may be present and incorporate some radionuclides and process contaminants. A brief description of the most important phases suitable for immobilization of ACTs and REEs is given below. 

Much stronger kinetic stabilization can be expected for processes leading to the inclusion of radionuclide ions into the colloid structure (Fig. 7, lower part). Spectroscopic indications for such processes have indeed been found again by TRLFS for the Cm(III) interaction with colloidal and particulate amorphous silica, calcite and CSH phases (Chung et al. 1998 Stumpf Fanghanel 2002 Tits et al. 2003). The incorporation of actinide ions into colloidal precursor clay phases has been recently investigated as a possible mechanism in natural... 

Mechanisms that may lead to the quasi irreversible binding of radionuclides to colloids belong to the key uncertainties of the assessment of the colloid problem. The kinetics of the dissociation of colloid-bound radionuclides are not yet understood. Radionuclide incorporation into stable colloids may enhance the colloid-mediated radionuclide release considerably. It is clear that only the investigation of the interaction mechanisms by spectroscopic methods is able to unravel the relevance of such processes. In order to allow the description of colloid-facilitated radionuclide migration, it is furthermore required to improve our understanding of the colloid interaction... 

The system has a specific capability for the resolution of very complex mixtures in which large energy peaks tend to mask small adjacent ones. It is therefore particularly suitable for rigorous studies of the slow incorporation of low levels of radionuclides into biological or environmental systems. It should encourage investigation in these areas, where up to now the accumulation of data has been slow, laborious, and expensive. 

Compute the amount of a radionuclide necessary to perform an experiment with a sample count rate of 1000 cpm, a detector efficiency of 33%, a sample aliquot for counting consisting of 10% of the total isolated sample and where the percent incorporation of the nuclide into the total isolated sample was 0.5%. 

Carriers frequently are stable isotopes of the radionuclide of interest, but they need not be. Nonisotopic carriers are used in a variety of situations. Scavengers are nonisotopic carriers used in precipitations that carry/incorporate other radionuclides into their precipitates indiscriminately. For example, the precipitation of Fe (OH)3 frequently carries, quantitatively, many other cations that are absorbed on the surface of the gelatinous precipitate. Such scavengers are frequently used in chemical separations by precipitation in which a radionuclide is put in a soluble oxidation state, a scavenging precipitation is used to remove radioactive impurities, and then the nuclide is oxidized/reduced to an oxidation state where it can be precipitated. In such scavenging precipitations, holdback carriers are introduced to dilute the radionuclide atoms by inactive atoms and thus prevent them from being scavenged. 

The oldest, most well-established chemical separation technique is precipitation. Because the amount of the radionuclide present may be very small, carriers are frequently used. The carrier is added in macroscopic quantities and ensures the radioactive species will be part of a kinetic and thermodynamic equilibrium system. Recovery of the carrier also serves as a measure of the yield of the separation. It is important that there is an isotopic exchange between the carrier and the radionuclide. There is the related phenomenon of co-precipitation wherein the radionuclide is incorporated into or adsorbed on the surface of a precipitate that does not involve an isotope of the radionuclide or isomorphously replaces one of the elements in the precipitate. Examples of this behavior are the sorption of radionuclides by Fe(OH)3 or the co-precipitation of the actinides with LaF3. Separation by precipitation is largely restricted to laboratory procedures and apart from the bismuth phosphate process used in World War II to purify Pu, has little commercial application. 

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