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  • Author or Editor: T. Ishii x
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Abstract  

The resolution of a 33±3 m microprobe focussed with quadrupole doublet installed at the 3 MV Van de Graaff of the National Institute of Radiological Sciences was used for this analysis. Brown algae, Hijiki,Hizikia fusiforme was the sample target bombarded with a 2 MeV proton beam collimated mechanically into a rectangular image of 100 m × 700 m. Scanning across the sample target prepared into a longitudinal section from the caulis of the algae provided the following observations. More than 12 elements such as Al, Si, P, Cl, Ca, Mn, Fe, Cu, Zn, As, Br and Sr were determined simultaneously, together with their distributional information across the diameter. In the medullary layer, Mn and Zn were specific in their accumulation, while the deposition of Fe, Cu, As and Br were observed to be high in the epithelial layer, especially Fe and Cu which were found on the surface, where they contact ambient sea water, but no significant change in pattern was indicated for such elements as Al, P and Cl. The PIXE microprobe analysis was, therefore, effective in its detectability for elements below a few ppm level, resultantly provides further possibilities for collecting information from bio-medical and environmental samples on trace characterization of elements.

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Abstract  

Thermal behaviors of POTMDM-net-PMMA and POTMG/PMMA blends were studied by DDSC. Tg of the polymer network was lowered by increasing the POTMDM in feed for copolymerization of POTMDM and MMA. A crystallization peak was observed only when MMA in feed was less than 30%. Tg of POTMG/PMMA was also lowered by decreasing the content of PMMA, however, the change was observed only when PMMA content was more than 70%. These results suggest that thermal transitions of the polymer network are restricted by the mesh size. POTM chains of the polymer network effectively play as a plasticiser.

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Interesting effects of fluoride additives, LiF, NaF and CaF2, on the solid-state reactions in the MgO - Cr2O3 and ZnO - Cr2O3 systems under an atmosphere of nitrogen were observed by means of DTA. For the MgO Cr2O3 - MF (M=Li, Na) systems, it was concluded that the melting of the fluoride additives plays an important role in accelerating the second reaction step at around 1000°. On the other hand, for the ZnO- Cr2O3 - MF (M=Li, Na) systems, a great acceleration by the additives was observed in the first reaction step at around 700°, a much lower temperature than the melting points of the fluorides. The effect of CaF2 was not clear in either system.

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Abstract  

Cowpea (Vigna unguliculata Walp) is considered one of the most drought resistant species among the pulse crops. It was suggested that in the lower part of the stem, parenchymatous tissue for storing water has been developed for the function of drought resistance. However, such tissue has not been identified yet. In order to identify the water storing tissue in the stem of cowpea plant, the authors performed neutron radiography, which provides a non-destructive image of water distribution pattern in a plant. Common bean plant and soybean plant were used as references. Comparing the neutron radiograph for the stems of the plants, i.e., cowpea, common bean and soybean plants, the parenchymatous tissue with water storing function was distinguished in the intermode between primary leaf and the first trifoliate leaf specifically in cowpea plant.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Sakashita, T. Hama, S. Fuma, M. Doi, Y. Nakamura, N. Ishii, and H. Takeda

Abstract  

To investigate the possibility of 14CO2 fixation using microorganisms in a high-dose area, the photosynthetic activity (specific production rate: SPR) and cellular proliferation (colony forming unit: CFU) of Euglena gracilis Z irradiated with gamma-rays at a dose of 0 to 500 Gy were determined. The dose responses of SPR and CFU suggested that it was possible to operate a CO2 fixation system of Euglena up to 100 Gy. Even at a dose of 500 Gy, about half of the photosynthetic activity under non-irradiated condition was considered possible.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: H. Muramatsu, S. Yoshizawa, T. Abe, T. Ishii, M. Wada, Y. Horiuchi, and R. Kanekatsu

Abstract  

The concentration of 7Be in surface air at Nagano City has been measured during the period from August 2000 to March 2005. The average monthly concentrations of 7Be in surface air were in the range of 3.3–14 mBq/m3 with pronounced two peaks in spring and autumn. It took 30–40 hours to recover the 7Be concentrations observed before, once 7Be was washed out by wet precipitations. For a pronounced increase in the concentrations of 7Be found in winter, a low-pressure trough coming close to the Japanese Islands with high concentrations of 7Be is responsible under the characteristic distribution of atmospheric pressure around the Japanese Islands.

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Abstract  

Chondritic meteorite samples were analyzed nondestructively by photon activation analysis. Powdered samples weighing about 50 mg each were irradiated with photons (-rays) converted from electrons accelerated by a linear electron accelerator at 20 and 30 MeV. With 30-minute and 6-hour irradiations, 11 and 12 elements with duplication of 6 elements could be determined, respectively. Considering that several major elements including Mg, Si and Fe can be determined in addition to Ti, Rb, Sr, Y and Zr, which cannot or hardly be determined by instrumental neutron activation analysis (INAA) with rather high sensitivity, instrumental photon activation analysis is as effective as INAA.

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Abstract  

Proton induced X-ray analysis has been studied by the 5 MV Van de Graaff of Tohoku University emphasizing on backing materials and angular dependence of background. The method has further been applied to analyses of some environmental samples. From experimental results, it was found that 4 μm Mylar foil among Formvar, Mylar and carbon gives sufficiently low background spectrum, high sensitivity and good mechanical strength. The detection limit is much improved at the backward direction with respect to the incident beam comparing with that at 90° which has usually been adopted. The analytical results on soil and aerosol samples were compared with those by the Atomic Absorption Spectrophotometrical method (AAS). Vanadium can easily be analysed by this method, but not by the AAS method. Milk and human milk were also analysed.

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Abstract  

Chemical effects on the intensity ratio of LX-ray of molybdenum compounds irradiated by 11-keV electrons and by 3-MeV protons were studied using an X-ray crystal spectrometer. It was found that the intensity ratios of L1/L1 markedly decrease with increase of ionicity of molybdenum compounds. An exception was for the case of metallic molybdenum.

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Abstract  

A macroporous silica-based supramolecular recognition absorbent (Calix[4] + Dodecanol)/SiO2–P, was prepared by successive impregnation and fixing the 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-Calix[4]arene (Calix[4]arene-R14) and its molecule modifier 1-Dodecanol onto SiO2 silica-based polymer support. The characterization of (Calix[4] + Dodecanol)/SiO2–P was examined by thermal gravimetry and differential thermal analysis and electron probe microanalysis. Relatively large separation factors of Cs and other metal ions (α Cs/M n+ ) above 60 were obtained in the presence of 3 M HNO3. The adsorption data of Cs(I) fitted well with Langmuir isotherm and the maximum adsorption capacity was estimated to be 0.19 mmol g−1. The Cs(I) in 3 M HNO3 were also effectively adsorption on (Calix[4] + Dodecanol)/SiO2–P in the column operation, and the loaded Cs(I) was successfully eluted with an eluent of H2O. The column packed with (Calix[4] + Dodecanol)/SiO2–P had excellent reusability after three cycles.

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