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  • Author or Editor: M. Bonardi x
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Abstract  

Excitation functions fornatZn (p, xn) and (p, pxn) nuclear reactions in the 5–45 MeV proton energy range were measured. Evaluations were made both of target thickness and proton energy in order to optimize the67Ga production rate, at the same time minimizing contamination by the66Ga. Optimal irradiation conditions, depending both on the beam current available and on the power dissipated into the target were determined.

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Abstract  

Proton activation analysis is applied to the determination of As in high-purity silicon, ion implanted with nominal doses ranging from 1014 to 1016 atoms/cm2. Both instrumental and radiochemical versions have been developed. The75 As(p, n)75Se,75 As(p, 3n)73Se and75 As(p, pn)74 As nuclear reactions have been considered in order to get the best activation conditions for delayed measurements by gamma spectrometry.

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Abstract  

Proton activation analysis (PAA) can be considered as complementary to NAA for the determination of elements of great environmental importance such as Pb, T1, Ti, Ge, V. The method was calibrated for the determination of lead in biological standard reference materials by instrumental analysis (IPAA), obtaining a detection limit of 0.1 ppm, for this type of matrices. Selective radiochemical separations in order to improve the sensitivity of the contemporary determination of Pb, T1, Ge ... are described in some details. A lead determination in pooled serum and red blood cells of 15 unexposed subjects by instrumental and radio-chemical analysis is carried out.

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Summary  

The fission of highly enriched uranium (HEU) by thermal neutrons creates dozens of isotopic products. The Isotope and Nuclear Chemistry Group participates in programs that involve analysis of “fresh' fission products by beta counting following radiochemical separations. This is a laborious and time-consuming process that can take several days to generate results. Gamma-spectroscopy can provide a more immediate path to isotopic activities, however, short-lived, high-yield isotopes can swamp a gamma-spectrum, making difficult the identification and quantification of isotopes on the wings and valley of the fission yield curve. The gamma-spectrum of a sample of newly produced fission products is dominated by the many emissions of a very few high-yield isotopes. Specifically, 132Te (T1/2 = 3.2 d), its daughter, 132I (T1/2 = 2.28 h), 140Ba (T1/2 = 12.75 d), and its daughter 140La (T1/2 = 1.68 d) emit at least 18 gamma-rays above 100 keV that are greater than 5& abundance. Additionally, the 1596 keV emission from 140La imposes a Compton background that hinders the detection of isotopes that are neither subject to matrix dependent fractionation nor gaseous or volatile precursors. Some of these isotopes of interest are 111Ag, 115Cd, and the rare earths, 153Sm, 154Eu, 156Eu, and 160Tb. C-INC has performed an HEU irradiation and also “cold' carrier analyses by ICP-AES to determine methods for rapid and reliable separations that may be used to detect and quantify low-yield fission products by gamma-spectroscopy. Results and progress are presented.

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Summary  

Radiochemistry laboratories are challenged to find efficient methods to handle a wide variety of sample types and sizes. To achieve accurate results, required decontamination factors and low detection limits, methods adequate for smaller, simpler matrices may need to be enhanced. This paper will review recent presentations made during Eichrom Users' Workshops. These include methods and data involving the analysis of actinides in large soil samples, 90Sr in bone, uranium in air filters containing significant 210Po and 99Tc in samples high in 234 Th.

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Abstract  

High specific activity radiotracers, used in studies related to trace elements and human health, must be characterized by the following specific requirements: (i) high specific activity (activity/mass of isotopic carrier), (ii) high activity concentration (activity/volume or mass of substrate), (iii) radionuclidic, radiochemical and chemical purities, (iv) biological compatibility (physiological pH, sterility and physiological values). For this purpose, selective radiochemical separations and quality control procedures have been developed and tested at our laboratories for the production of several NCA radiotracers.

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Abstract  

The atmospheric particulate of industrialized cities had become a mixture of potentially toxic substances whose concentrations must be monitored to assess the pollution levels. Trace metals and elements are part of these pollutants and the knowledge of their total concentration in the air as well as their distribution in the different aerosol particle sizes is necessary to evaluate the pollution risk in terms of maximum present levels and long term exposure. In the present work, a preliminary part of a study initiated for monitoring the trace element levels present in the atmospheric particulate of the city of Milan (north Italy) and of its suburban areas is presented. More than 25 elements have been determined in Milan downtown along a period of three years and in different weather conditions. The granulometric distribution of selected potentially toxic elements (such as vanadium, lead, cadmium, nickel) has been also determined to evaluate their concentrations in different inhalable fractions (alveolar and bronchial — tracheal). Instrumental Neutron Activation Analysis (INAA) has been used for the determination of the great part of the elements while Graphite Furnace Atomic Absorption Spectroscopy (GF-AAS) has been employed for the determination of lead and, in some cases, for nickel, cadmium and copper.

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Abstract  

High specific activity radiotracers are very suitable for studies related to the toxicological impact of trace elements onto human health. In order to investigate the metabolic behaviour of Low Level Exposure (LLE) to trace elements, it is necessary to carry out in-vitro and in-vivo experiments with tracers whose concentration is of the same order of magnitude as the present environmental exposure values (ng-g/kg day). Preparations, separations and purifications of some No Carrier Added (NCA) radiotracers (48V,95m,96Tc,195m,g,197m,gHg,199Au,202Tl) produced by either cyclotron or nuclear reactor irradiation, are presented and discussed. This work reviews the more recent advances in this field carried out by our groups.

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Abstract  

[186gRe]Re-HEDP is a radiopharmaceutical used for pain palliation in bone metastases from various primary tumors. The negatron emitter with 〈E β〉 = 357 keV 186gRe is suitable to irradiate cancer and inflammatory cells, but it needs labeling bis-phosphonates as vectors to reach target tissue. Paper radiochromatography was used to evaluate the radiochemical purity of [186gRe]Re-HEDP in radiopharmaceutical solution as well as in biological samples (serum and urine) from treated patients, in order to follow bone-targeting and excretion. Following the activity concentration in each sample vs. time it is effective to elaborate a bio-kinetic model of the radiopharmaceutical and to optimize administration protocols.

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