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- Author or Editor: H. Nakahara x
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Abstract
Use of an enriched isotope as an activable tracer is proposed for the preconcentration of trace elements in neutron activation analysis. As a test of this method, contents of cadmium in various biological standard samples were determined by addition of an enriched116Cd tracer in the preconcentration step followed by neutron irradiation and 
-ray spectrometry. The principle, advantage, and limitations of the method are also discussed.
Abstract
Prompt 
-ray analysis with the internal monostandard method was used to organs taken from rats. After B or Cd was administered, the B/H and Cd/H contents ratios were determined in the brain, kidney, and liver to study their distribution and metabolism. Boron was distributed in all organs but metabolized quickly. Cd was slowly accumulated in the liver and kidneys during the 65 hours studied but no Cd was detected in the brain.
Abstract
Use of an enriched156Dy isotope as an activable yield tracer for the determination of lanthanoid contents in various biological reference materials has been proposed. The method consists of preconcentration of the lanthanoid in the156Dy doped samples followed by neutron irradiation and further chemical purification steps. The chemical behaviour of lanthanoid elements in the whole procedure was found, in separate runs, similar to that of the added156Dy within experimental errors. Simple purification steps after irradiation allow the measurement of relatively short-lived nuclides and diminish the radiation dose received during the chemical treatment. The present results for orchard leaves (NBS SRM 1571) are generally in good agreement with the previously reported data. Some new data are obtained for other biological reference materials.
Abstract
KX-ray-gated emission Mössbauer spectra of57Co-labelled CoF2 and CoF2.2H2O were measured at room temperature, using the coincidence technique. A difference was found in the relative intensity of57Fe(II)/57Fe(III) between the X-ray-gated and non-gated emission spectra. The results are explained in terms of local radiolytic effects of water of crystallization and the chemical effects associated with the de-excitation processes caused by EC-decay.
Abstract
The improvement obtained by epithermal neutron activation analysis was studied in terms of the detection sensitivity and precision in the γ-ray spectrometry for geological and biological reference samples. For geological samples, small improvement was observed only for the elements As, Ba, Sb, Se and U. For biological samples, however, large improvement was observed for As, Br, Sb and U. The ratio of the resonance integral to the effective thermal-neutron capture cross section was observed for 19 nuclides. The effect of the (n, p) reaction to the determination of Al and Mg by the ordinary reaktor-neutron activation analysis was estimated.
Abstract
Nondestructive determination of major and trace elements within voluminous materials has been demonstrated by prompt γ-ray neutron activation analysis. Some fragmented pieces of pottery bowls considered to have been produced in the late 18th century were analyzed by a new internal monostandard method, and noticeable differences of the elemental contents and significant correlations of the elemental distributions were observed among the samples. The possibility of identification of producing areas of unearthened material is demonstrated by the analytical results and the applicability of this method to the investigation of precious samples in a completely nondestructive way is verified in practice.
Abstract
The effect of β−-decay on the stability of metallofullerenes was investigated for three decay chains of155Sm-155Eu,161Gd-161Tb and177Yb-177Lu. For the former two cases, the metallofullerenes were found stable even after the β−-decay while in the case of177Yb, the metallofullerene became unstable after β−-decay. The present results point to the fact that metallofullerenes are stable against ordinary β−-decay unstable after β−-decay. The present results point to the fact that metallofullerenes are stable against ordinary β−-decay recoil energies, but they become unstable if the oxidation state of the metal atom is changed by nuclear transformation.
Abstract
Neutron activation analyses were performed for the newly issued reference rocks, GSJ JA-1 and JB-2, and also for the widely distributed GSJ JG-1 and JB-1. The contents of fourteen elements could be newly determined for the former two rocks and those of eleven elements were re-determined for the latter rocks.
Abstract
The thermal decomposition of methano-fullerene derivatives such as ethoxycarbonyl methano[60] fullerene and various isomers of bis-(ethoxycarbonyl methano)[60] fullerene leads to new fullerene derivatives, which have been preliminary characterized. The analysis of separated species was performed by UV-VIS, IR, H- and C-NMR, STM, FAB, LDI and MALDI-TOF MS spectroscopy. One of the isolated phases is a C122 molecule with a dumbbell-like structure.
Abstract
Neutron-induced prompt gamma-ray analysis (PGA) was applied to seven meteorite samples (Allende, Zagami, Acfer 209, ALH77005, ALH84001, EET79001 and Neagari). Samples were irradiated in both the thermal neutron and the cold neutron guided beams of JRR-3M at JAERI. Multiple samples of an Allende standard powder were analyzed for Si using two different methods: (1) the comparison method, using a Si standard, and (2) the mono-standard method, using Fe as an internal reference element. The Si concentrations determined by these two methods are in good agreement with literature values. The analytical sensitivity for Si using the cold neutron guided beam is∼14.3× higher than that for the thermal neutron guided beam. Other elements determined (B, Ca, Ti and S) also showed higher sensitivities using the cold neutron beam. The other meteorites studied showed some anomalous B and S values likely due to the effects of terrestrial weathering/contamination.
