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  • Author or Editor: T. Kato x
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Abstract  

A nondestructive photon activation analysis with 30 MeV bremsstrahlung has been applied to the multielement determination in the floor sediments in a region of the Japan Sea. The abundances for 5 major and 11 trace elements were measured in several terrigeous and pelagic deposits, discussion being given on the results. Enrichments in certain trace elements, such as Mn, Ni and Co, were observed in the samples of pelagic areas, but to less extent relative to those of the mid-Pacific areas.

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Abstract  

Yields of the photonuclear reactions of various types induced in 71 elements have been determined experimentally by means of bremsstrahlung irradiation with different maximum energies, and detection of the resultant activities with a lithium-drifted germanium detector. From the results obtained, sensitivities in photon-activation analysis were evaluated and the reactivity of high-energy photons with nuclei in a wide range of atomic number was discussed.

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Abstract  

Iodine abundances in NBS biological SRMs and various organs of rats were evaluated by epithermal neutron activation analysis with a boron carbide filter. Detectability of iodine in different biological materials by this method is discussed.

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Abstract  

The trace element levels in various organs of normal rats have been determined by means of thermal neutron activation followed by high-resolution gamma-spectroscopy. Abundances for 11 elements (Cu, Mn, Fe, Zn, Rb, Sb, Se, Cr, Co, Cs and Sc) were evaluated in the individual subjects. The present results were generally found within the ranges of the literature values, except for ultra-trace elements. Reliability of the method was assessed by analyzing NBS standard reference materials, Orchard Leaves and Bovine Liver. The trace element contents of the rat diet have also been measured, and comparison of them with those of the rat organs was given.

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Abstract  

The combination of photon activation and solid state γ-ray detection provides a very effective method of analysis of rare earths. The present report describes the production rates of almost all of the product nuclides found in yttrium and 14 rare earths irradiated with 70 MeV bremsstrahlung photons from an electron synchrotron. A 20 cm3 lithium-drifted germanium diode was used as a detector. Sensitivities of this method have been summarized for photon activation analysis, and experimental reaction yields have been obtained in order to discuss the reactivity of high-energy photons with nuclei in the rare earth region.

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Résumé  

On a appliqué l'activation aux photons à l'analyse non-destructive de roches étalons USGS. 16 éléments sont dosés. On a irradié simultanément l'échantillon de roche et les étalons multiéléments dans un bremsstrahlung de 30 MeV, et on a mesuré l'activité des adioisotopes produits par les réactions (λ,n)et (λ,p) avec un détecteur Ge(Li). La validité de la méthode est démontrée par les résultats obtenus pour ces roches. Les résultats concernent les éléments suivants: Na, Mg, Ca, Ti, Cr, Mn, Fe, Co, Ni, Rb, Sr, Y, Zr, Nb, Ba et Ce.

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Abstract  

A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is quite simple and gives good reproducible results for at least 12 elements.

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Abstract  

Rate constant of intermolecular electron transfer (ET) in a photoexcited donor-acceptor model system solvated by a cluster of polar molecules has been expressed in terms of the statistical distribution of the electrostatic potential energy difference between the reacting sites. This distribution has been calculated for a particular case of acetonitrile clusters a ≈120 K by MD computer simulation. The MD values of the cluster reorganization energy and the ET rate constant have been compared with the corresponding MD results for the donor-acceptor pair solvated in bulk acetonitrile and with theoretical predictions based on the continuum model.

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Abstract  

Luminescence lifetime of Eu(III) in polyacrylate and polymaleate complexes has been measured to evaluate the number of water molecules bound to the ion. The number of residual water molecules hydrated to Eu(III) in the polyacrylate and polymaleate complexes ranged from 3.5 to 4.5 when the supporting electrolyte concentration was 0.01. The residual hydration number decreased with the addition of supporting electrolyte. These results indicate that Eu(III) is surrounded by polymolecular ligands in these complexes.

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Abstract  

A comprehensive study on the yields of photonuclear reactions of various types has been performed, and sensitivities and the effects of interferences in multielement photon-activation analysis have been evaluated by bremsstrahlung activation of many elements with maximum energies ranging from 30 to 60 MeV. The applicability and reliability of the method were demonstrated by analyzing standard round-robin samples and then by presenting the elemental abundances in several geological, biological and environmental materials. The method was almost insensitive to matrix effects and was assessed to be promising for nondestructive multielement determination of the materials of wide variety, giving good reproducible results for 20 or more elements.

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