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Abstract  

Multiple radionuclide mixtures which have similar scintillation pulse height distributions can be accurately radioassayed by the most probable value theory. This liquid scintillation technique is based on the construction of more observation equations than the number of nuclides to be analyzed. The technique has been applied to3H–14C–125I and3H–14C–51Cr mixture samples, and found to be very practicable with the aid of computerized data processing for mixture samples having a wide range (ca. 10 times) of activity ratios.

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Abstract  

The resistance against radiation of the tertiary pyridine resins synthesized for the treatment of spent nuclear fuels and high level radioactive waste was evaluated. After irradiation at 10 MGy, only approximately 10% or less of the exchange groups were lost in HCl solutions regardless of their concentrations, while 3040% were lost in HNO3. The pyridine resin has shown remarkable resistance against radiation particularly in HCl solution. It has been revealed that the decomposition of pyridine type resins results from the scission of the principal chains. An irradiation study was conducted also on the quaternary ammonium resins. Quatemization ratio was found to be reduced in HNO3 solutions at 10 MGy irradiation.

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Abstract  

The isotope fractionation of potassium in an aqueous (KOH)/amalgam system has been studied. Two types of isotope effects with opposite isotope enrichment directions were observed in the electrolysis of potassium from the aqueous into the amalgam phase under constant electrolytic potentials. It was found that the first isotope effect causing the light isotope enriched in the amalgam is related to the kinetic process of the mass transfer through the aqueous/amalgam interface, while the second one leading to the enrichment of the heavy isotope in the amalgam phase is produced by the isotope-exchange equilibrium. The temperature dependence of the equilibrium isotope effect was also investigated using single-stage and multi-stage techniques. It was observed that the equilibrium isotope effect increases as the temperature increases in the range of 293-371 K. An empirical equation was used to fit the variations of the isotope effects with temperature for potassium together with the other alkaline and alkaline earth metals studied in the same system. The origin of the equilibrium isotope fractionation in the electron-exchange system was discussed. Furthermore, the mass dependence of the separation coefficients of the alkaline and alkaline earth metals observed in aqueous/amalgam and ion-exchange systems were compared. At 293 K the equilibrium isotope separation coefficient for the 39K/41K isotopes in the amalgam system was determined as (5.6±0.6).10-3.

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Abstract  

The separation of strontium from other alkaline earth elements and alkali metal elements is necessary for precise strontium isotope measurement in natural samples. The adsorption behavior of alkaline earth elements on tertiary pyridine resin was investigated using the methanol/nitric acid mixed solution, and the feasibility of strontium separation was studied. We found that strontium can be completely separated from other alkaline earth elements and alkali metal elements using the tertiary pyridine resin. The extraction of strontium from coral sample was demonstrated.

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Abstract  

In this work, we determined the levels of trace metals in protein fractions isolated from rock oysters by neutron activation analysis (NAA) and particle induced X-ray emission (PIXE). Proteins were extracted from mantles and hepatopancreases of rock oysters and fractionated by size-exclusion high performance liquid chromatography (HPLC). The protein fractions from mantles and hepatopancreases are found to be abundant in Fe, Cu, Zn, Mn, Pb, and Ag. HPLC profiles of Fe, Cu, Zn, and Ag indicate that those elements are bound to proteins extracted from mantles and hepatopancreases.

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Abstract  

The most probable value theory has been applied to analytical radioassay for mixture samples of six pure-beta emitters by using a liquid scintillation spectrometer. Activities of each nuclide in the mixture sample can be determined by solving normal equations which are derived from twelve observation equations, the number of which is twice that of nuclides to be radioassayed. Requirement for the technique is to construct quenching correction curves of the respective nuclides. This technique has been tested to3H–63Ni–14C–45Ca–36Cl–32P mixture samples, and found to be very useful with the aid of computerized data processing.

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Abstract  

The synthesis of [γ-32P]ATP with high specific radioactivity was investigated by the enzymatic method. We utilized a part of the glycolytic pathway which consists of three reaction steps. First, we examined the maximum radioactivity of H3 32PO4 without the decrease of labeling yield. Next, we examined the minimum amount of reagent without the decrease of labeling yield, because some reagents contain the phosphorus species as impurity. In this paper, we propose the optimum condition for synthesis of [γ-32P]ATP with high specific radioactivity. As our calculation, we will be able to obtain about 220 TBq/mmol specific radioactivity using 1.5 GBq of H3 32PO4.

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Summary  

An efficient method for the isolation of iodine-accumulating bacteria was established. A total number of 138 bacterial strains were grown on agar media containing 125I, and the strains having strong radioactivity were chosen by autoradiography. They were then grown in liquid media containing 125I, and the radioactivity of the cells and the supernatants was determined after centrifugation through silicone oil. Eight strains were found to remove 78 to 90% of iodine from the media within 24 hours, and corresponding amount of iodine was detected in their cells. The advantage of this method is in its simplicity and the low detection limit.

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Abstract  

We have investigated the concentrations of REEs in fern leaves collected indifferently to the fern species from 9 sampling sites in Japan using INAA. The results indicated a large variation in the values obtained between fern leaves. In the present investigation we applied the same analytical method on the samples (Blechnaceae, a kind of fern, mature and developing leaves were collected from the same plant) restrictively gathered from the University Forests in Ashiu, Kyoto University. It was demonstrated that the variations in the REE concentrations decreased by one to two order of magnitude, and that the REE contents in developing leaves were also one to two orders of magnitude lower than those in mature leaves. It can be considered that fern accumulates REEs with their growth stages.

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Journal of Thermal Analysis and Calorimetry
Authors: K. Fujii, Y. Matsumoto, Y. Kaieda, D. Kobayashi, Y. Umebayashi, and S. Ishiguro

Abstract  

Cobalt(II) chloro complexation has been studied by titration calorimetry and spectrophotometry in solvent mixtures of N-methylformamide (NMF) and N,N-dimethylformamide (DMF). It revealed that a series of mononuclear CoClnn (2–n)+ (n=1–4) complexes are formed in the mixtures of NMF mole fraction x NMF=0.05 and 0.25, and the CoCl+, CoCl3 and CoCl4 2– complexes in the mixture of x NMF=0.5, and their formation constants, enthalpies and entropies were obtained. As compared with DMF, the complexation is markedly suppressed in the mixtures, as well as in NMF. The decreasing formation constant of CoCl+ with the NMF content is mainly ascribed to the decreasing formation entropy. DMF is aprotic and thus less-structured, whereas NMF is protic to form hydrogen- bonded clusters. In DMF-NMF mixtures, solvent clusters in neat NMF are ruptured to yield new clusters involving DMF, the structure of which depends on the solvent composition. The entropy of formation of CoCl+ will be discussed in relation to the liquid structure of DMF, NMF and their mixtures.

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