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  • Author or Editor: D. Jia x
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Abstract  

A simple, sensitive and selective method is described for the simultaneous determination of plutonium and americium in lichen and moss samples which can be used as the atmospheric radioactivity bioindicators. Plutonium is separated from a HCl leaching solution by a Microthene-TNOA column; americium is separated by a KL-HDEHP column and purified by PMBP-TOPO extraction. A special attention has been paid to the decontamination of plutonium and americium from210Po. Ten lichen and 12 moss samples from tree trunks have been analyzed: starting from 2 g sample, the average yields and the detection limits were 70.2±12.5% and 28 mBq/kg for plutonium and 70.0±15.1% and 34 mBq/kg for americium. The concentrations (mBq/kg) ranged from 28 to 4960 for239,240Pu, from 28 to 171 for238Pu and from 34 to 1930 for241Am, respectively.

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Abstract  

A sensitive and reliable metbod for the sequential separation and determination of plutonium,241Am and90Sr in soil samples was developed. Plutonium was separated by a Microthene-TNOA column. Then90Y (for90Sr determination) was separated from americium by a HDEHP column after elimination of large amounts of interfering stable or radioactive nuclides (iron,210Bi and210Po etc.) by an oxalate precipitation and a Microthene-TNOA column. Finally americium was purified by another HDEHP column and a PMBP-TOPO extraction. A special attention was paid to the decontamination of Pu and Am from210Po and of90Y from210Bi; the relevant decontamination factors resulted greater than 105, 106 and 104 respectively. The detection limits were 1.2 mBq/kg for Pu and 1.7 mBq/kg for241Am and 0.32 Bq/kg for90Sr. The procedure was checked by analyzing three certified samples supplied by IAEA. Some Italian soil samples were also analyzed giving average yields of 84.9±7.2% for Pu, 57.8±3.2%for Am and 96.7±1.6% for Y; the239+240Pu,238Pu,241Am and90Sr contents (Bq/kg) ranged from 0.347 to 1.53, from 0.013 to 0.048, from 0.126 to 0.556 and from 2.89 to 11.6 respectively and the average ratios were 0.037±0.017 for238Pu/239+240Pu, 0.357±0.040 for241Am/239+240Pu and 7.0±1.2 for90Sr/239+240Pu.

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Abstract  

Many lanthanide radionuclides, having various nuclear properties but similar chemical properties, are considered suitable for different radiotherapeutic applications. This paper describes the production of a number of radiolanthanides (e.g.153Sm,166Dy,166Ho,161Tb and177Lu) and the radiotherapy research involving these radionuclides at the University of Missouri Research Reactor Center (MURR).

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Abstract  

A radiochemical method is described for the determination of238Pu,239(240)Pu and241Am in a single soil sample. Plutonium is separated from a HNO3 leaching solution by a Microthene-TNOA column; amcricium is coprecipitated by oxalic acid, decontaminated from polonium by a TNOA-column in HCl medium, separated from the rare earth elements by a Microthene-HDEHP column, eluted with a 0.07M DTPA+1M lactic acid solution and finally purified by a PMBP-TOPO extraction. The method supplies a good decontamination of Am and Pu from natural alpha emitters; starting from 50 g soil, the average yields were 75.1±13.4% for plutonium and 57.7±10.8% for Am.239(240)Pu,238Pu and241Am concentrations (mBq/kg) in three different kinds of soil were the following: 255, 10.4, 81.3 (uncultivated soils); 236, 11.6, 76.7 (cultivated soils); 46, 1.9, 19.8 (river sediment). The average ratios238Pu to239(240)Pu and241Am to239(240)Pu were 0.044 and 0.350, respectively.

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Abstract  

Thermal behaviors of two mixed-ligand complexes, [Ni(PMPP-SAL)(Py)3] and [Cu(PMPP-SAL)Py]·MeOH, (PMPP-SAL=1-phenyl-3-methyl-4-(salicylidene hydrazide)-propenylidene-pyrazolone-5, Py=pyridine), were studied by TG-DTG-DTA in dynamic air atmosphere. The complexes show the loss of pyridine molecule is followed by the decomposition of the PMPP-SAL anion and give respective metal oxides as residues. Meanwhile, the Ozawa-Flynn-Wall model-free analyses and multivariate non-linear regressions were applied to perform single and overall steps optimization. Kinetic parameters were given and the most probable mechanism functions were suggested in this study.

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Abstract  

We have examined the uptake of actinide elements Am and, Pu by different species of lichen and moss collected in two locations (Urbino, Central Italy; Alps region, North-east Italy). Plutonium and americium were separated and determined by extraction chromatography, electrodeposition and alpha-spectrometry. This paper summarizes our results with a special emphasis on the vertical profiles of these actinides in two different species of mosses. Several 1–2 cm depth sections were obtained and dated by210Pb method. A typical peak for239,240Pu and241Am was found in the very old moss species (“Sphagnum Compactum”) at a depth corresponding to the period 1960–1970 which was the period characterized by the maximum nuclear weapon tests. In a younger moss species (“Neckeria Crispa”) no peak was observed and the regression curves showed that Am is more mobile than239,240Pu and238Pu.

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Abstract  

Separation chemistry plays an important role when alpha-and beta-emitting natural and artificial radionuclides at low levels must be determined in complex environmental matrices. This paper describes some separation techniques used in radioecology, with special emphasis on extraction chromatography. The very high necessary decontamination factors are pointed out together with the suggested techniques. The following examples are given: (a) determination of90Sr in soils in the presence of high concentration of210Bi; (b) determination of cosmogenic32P in sea water and its decontamination from234Th; (c) determination of63Ni and59Ni in liquid effluents; (d) separation techniques used for the speciation of plutonium in sea sediments and (e) plutonium and241Am concentration and vertical distribution in mosses.

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Abstract  

A microcalorimetric technique was used to evaluate the influence of La3+ on mitochondria isolated from the liver tissue of Avian chicken. By means of LKB-2277 bioactivity monitor, ampoule method at 37C, we obtained the thermogenic curves of the metabolism of mitochondria. After isolation from the chicken liver tissue, mitochondria still have metabolic activity and can live for a long time depending on the stored nutrients. In order to analyze the results, the maximum power (P m) and the decline rate constants (k d) were obtained. The addition of La3+ results in an increase of the maximum heat production and decline rate constants. Furthermore, values of P m and k d are linked to the concentration of La3+. According to the thermogenic curves under different conditions, it is clear that metabolic mechanism of mitochondria has been changed with the addition of La3+.

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