Radioactivity residual activity

If the presence of radon 222 in a water sample can be verified in this manner, and if an airtight water sample is examined again after, for example, 5 half-lives and radon 222 radioactivity (residual activity) is... 

Williams [176] has studied the rate of oxidation of C-labelled glucose in seawater by persulfate. After the oxidation, carbon dioxide was blown off and residual activity was measured. For glucose concentrations of 2000, 200, and 20 xg/l, residual radioactivities (as percentage of total original radioactivity) were 0.04, 0.05, and 0.025, respectively, showing that biochemical compounds are extensively oxidised by persulfate. With the exception of change of temperature, modifications of conditions had little or no effect. Oxidation for 2.5 h at 100 °C was the most efficient. 

Bathymetry changes (seabed) Residual underground radioactivity Residua radioactivity and activation X X X X X X... 

Metabolite Profiles in Liver. The total radioactive residue in all 12 livers was efficiently extracted with a mixture of formic, trifluoroacetic, and hydrochloric acids. After neutralization of the acids with ammonium hydroxide and partial purification by solid phase extraction techniques, HPLC/RAM analysis produced essentially a two-component profile. The minor component was pirlimycin itself in relative amounts of 27.6% 9.7%. The bulk of the residue, 77%, was a single substance and was identified by co-chromatography with an authentic standard and by FAB/MS as pirlimycin sulfoxide (PS). The microbiological analysis of the extracts confirmed this relative ratio since PS has an antibiotic activity 142 times less than that of pirlimycin against M.luteus. The ratio of pirlimycin to total residue was therefore established and will provide the necessary correlation of residue depletion needed for the calculation of residue marker concentration (Rm) and the establishment of a tissue withdrawal period. 

Not only must the experimental radioactive materials be stored properly, but all of the waste products which could contain any residual active materials must be kept and stored within the laboratory until they can be disposed of safely, usually by a radiation safety specialist. The temporary storage of radioactive waste gives rise to the possibility of accidental removal of the radioactive waste as ordinary trash. Any trash containers containing radioactive waste should be distinctively marked, and custodial persormel should receive special training to recognize the... 

For determining what is known as the residual activity, water samples are filled into bottles which can be closed airtight, so that they can be analyzed for their radon content in the laboratory at a later stage, possibly after radioactive equilibrium has been established. For this, 1-litre or 2-litre glass bottles with double-bore rubber stoppers are used. 

Unexpectedly, some radiolabel did appear on the ester carbonyl of resin-retained and autocleaved esters. The ratio of C radiolabel of ester carbonyl and keto group could be determined by measuring the radioactivity of the carbon dioxide produced by keto ester hydrolysis and decarboxylation, as well as residual activity in the ketone. The ratio of C label in ester carbonyl and keto groups is presented in Table 9-1. 

The values of activity concentration provided in this Safety Guide are not intended to be applied to the control of radioactive discharges of liquid and airborne effluents from authorized practices, or to radioactive residues in the environment. Guidance on the authorization of discharges of liquid and airborne effluents and the reuse of contaminated land is provided in Refs [9, 10],... 

At Final End State it is expected that the site will be removed from the nuclear licensing regime. The relevant test is A demonstration that any residual activity, above background radioactivity, which remains on the site, which may or may not have arisen from licensable activities, will lead to a risk of death to an individual using the site for any reasonably foreseeable purpose, of no greater than 1 in a million per year . ... 

The same group (Kirby et ai, 1978) tested the status of 12 as a free intermediate in T. viride by an intermediate-trapping experiment. Non-radioactive 12 was incubated with the organism and, 2 hr later, L-[t/- C]-phenylalanine was added to the medium. The culture filtrate was extracted with chloroform to remove gliotoxin and then with ethyl acetate to remove the cyclodipeptide (12). This was diluted with pure, inactive 12, and the mixture crystallized to constant " C activity. The residual activity corresponded to 1.3% of that administered as L-[f/- C]phenylalanine. Thus, 12 had been formed from phenylalanine and is presumably present in the organism under normal conditions of growth. It remains to be seen whether... 

Radioactivity in environmental waters can originate from both natural and artificial sources. The natural or background radioactivity usuaUy amounts to <100 mBq/L. The development of the nuclear power industry as weU as other industrial and medical uses of radioisotopes (qv) necessitates the deterrnination of gross alpha and beta activity of some water samples. These measurements are relatively inexpensive and are useful for screening samples. The gross alpha or beta activity of an acidified sample is deterrnined after an appropriate volume is evaporated to near dryness, transferred to a flat sample-mounting dish, and evaporated to dryness in an oven at 103—105°C. The amount of original sample taken depends on the amount of residue needed to provide measurable alpha or beta activity. 

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