[en] Effects of main magnetic field time-variation upon MR (Magnetic Resonance) images are presented. In permanent magnet MRI system, main magnetic field strength varies linearly with time according to the magnet's temperature variation. The effects of this field strength time-variation upon MR images are simply. (author)

[en] An echo-time encoding proton NMR chemical shift imaging proposed by Dixon is extended to be applicable to low filed systems. The method utilizes the small phase angle between magnetic vectors of water and lipid protons to decrease the signal decays with spin-spin relaxation. The inevitable phase error caused by the static field inhomogeneity is corrected by using phase images of phantom measured under the same conditions as the actual measurements. The experiments were carried out using CuSO₄ doped water and vegetable oil at 0.5 T. Two chemical shift images could be clearly resolved with only one scan when the field inhomogeneity was larger than the chemical shift difference. (author)

[en] A new particle recovery method and a sensitive screening method were developed for subsequent isotope ratio analysis of uranium particles in safeguards swipe samples. The particles in the swipe sample were recovered onto a carrier by means of vacuum suction-impact collection method. When grease coating was applied to the carrier, the recovery efficiency was improved to 48±9%, which is superior to that of conventionally-used ultrasoneration method. Prior to isotope ratio analysis with secondary ion mass spectrometry (SIMS), total reflection X-ray fluorescence spectrometry (TXRF) was applied to screen the sample for the presence of uranium particles. By the use of Si carriers in TXRF analysis, the detection limit of 22 pg was achieved for uranium. By combining these methods with SIMS, the isotope ratios of ²³⁵U/²³⁸U for individual uranium particles were efficiently determined. (author)

[en] JAEA has been developing, under the auspices of the Ministry of Education, Culture, Sports, Science and Technology of Japan, analytical techniques for ultra-trace amounts of nuclear materials in the environmental samples in order to contribute to the strengthened safeguards system. In January 2003, JAEA was qualified as a member of the IAEA Network Analytical Laboratories (NWAL) for environmental sample analysis. Since then, JAEA has conducted the analysis of domestic and the IAEA samples. Two techniques, bulk and particle analyses, are available for the environmental samples and the latter method generally provides more detailed information about history of nuclear materials in a facility. However, isotope ratios of uranium are measured in the particle analysis at present and it is wished to develop analytical method for isotope ratios of plutonium in individual particles. We commence the development of the plutonium particle analysis and the consideration of age-dating for plutonium particles through the atomic ratio of Pu-241 and Am-241. At the presentation, our activities as a member of IAEA NWAL and current status for the development of the analytical methods will be discussed. (author)

[en] Highlights: • Isotopic ratios of NO₃⁻ were determined in municipal wastewater treatment processes. • Spatial change in stable isotope ratios was found within treatment steps. • Isotope signatures rely on treatment types and steps. • Treatment performance and characteristics may influence isotopic fluctuation. Stable isotope ratios of nitrate are a powerful tool to evaluate aquatic environment stress from treated and untreated sewage. However, there is generally a lack of knowledge on the change in stable isotope ratios within wastewater treatment plants. We investigated nitrogen and oxygen stable isotope ratios (δ¹⁵N and δ¹⁸O) of nitrate in four types of advanced treatment processes operated in parallel; (A) extended aeration activated sludge, (B) anaerobic-anoxic-aerobic (A²O), (C) recycled nitrification-denitrification, and (D) modified Bardenpho. The results exhibited spatial variation of δ¹⁵N and δ¹⁸O for nitrate within the treatment steps. The changes in δ¹⁵N and δ¹⁸O may result from the reactor conditions (aerobic, anoxic, and anaerobic) and the order of these processes. As decreasing nitrate concentration in the anoxic stages, the δ¹⁵N/δ¹⁸O ratio for nitrate increased at a rate of 1.3 to 1.6 coupling with the reduction in the nitrate concentration in the anoxic stages. The δ¹⁵N and δ¹⁸O signatures were attributed to process performance in regard to nitrogen removal. In particular, the modified Bardenpho process has higher nitrogen removal efficiency over other processes, producing effluent with lower nitrate concentration and higher stable isotopes (δ¹⁵N: 23.6 to 25.5‰, δ¹⁸O: 2.8 to 4.5‰). We concluded that the stable isotope signatures mirrored the treatment efficiency and effluent characteristics.

[en] JAEA has been developing analytical techniques for ultra-trace amounts of nuclear materials in the environmental samples in order to contribute to the strengthened safeguards system. Development of essential techniques for bulk and particle analysis of the environmental swipe samples has been established as ultra-trace analytical methods of uranium and plutonium. In January 2003, JAEA was qualified as a member of the IAEA network analytical laboratories for environmental samples. Since then, JAEA has conducted the analysis of domestic and the IAEA samples. JAEA is developing the analytical techniques to improve the analytical ability for the safeguards environmental samples. For bulk analysis, study is focused on the improvement of reliability of isotope ratio measurements by ICP-MS. New chemical separation techniques are under development and a desolvation module is introduced to reduce the polyatomic interferences. In particle analysis, the sample preparation procedure for SIMS method is modified to measure the ²³⁴U/²³⁸U and ²³⁶U/²³⁸U ratios for individual particles. We are also developing fission track-TIMS method to measure uranium isotope ratios in particles of sub-micrometer size. A screening instrument of X-ray fluorescent analysis is equipped to measure elemental distribution on a swipe surface. (author)

[en] The dependence of the precision of uranium isotope ratio on particle diameter in secondary ion mass spectrometry (SIMS) was investigated. Each uranium particle in certified reference materials with different isotopic composition (²³⁵U/²³⁸U = 0.01-1.00) was observed with a scanning electron microscope (SEM) and transferred by a manipulator on a glassy-carbon planchet for subsequent isotope ratio analysis with SIMS. The relative standard deviation (RSD) of uranium isotope ratios varied with particle diameter, the amount of less abundant uranium isotope and the number of measurement cycles. For the particle with the diameter less than 1.0 μm, the RSD significantly increased with increasing the number of measurement cycles, which is due to the difficulty of obtaining constant signals for a long duration. In contrast, no significant increase in the RSD was observed in the analysis of the particle with the diameter larger than 2.0 μm. As the results, it is estimated that the ²³⁵U amount of 4.5 fg is sufficient to obtain the ²³⁵U/²³⁸U ratio with the RSD within 5.0%. For the analysis of minor isotopes, the ²³⁴U amount of 0.42 fg and the ²³⁶U amount of 1.1 fg are sufficient to obtain the ²³⁴U/²³⁸U and ²³⁶U/²³⁸U ratios with the RSD within 20%, respectively

[en] Japan Atomic Energy Research Institute (JAERI) has been developing techniques for the environmental sample analysis since 1996. A clean-room facility named as Clean Laboratory for Environmental Analysis and Research (CLEAR) was constructed in 2001. By the end of 2002, fundamental techniques for ultra-trace analysis of uranium and plutonium were established with sufficient sensitivity and accuracy. This resulted in the qualification of JAERI, in 2003, as a member of the IAEA Network of Analytical Laboratories (NWAL) with regard to both particle analysis and bulk analysis, the latter of which covered hot-cell swipe samples as well. Thereafter JAERI has contributed to the international safeguards as well as to the domestic safeguards, by carrying out the analysis of safeguards environmental sample. Since 2003, the second phase was started to develop advanced techniques, with which JAERI aims at technical support to the enhancement of safeguards system. This paper deals with the R and D activities at JAERI in the field of safeguards environmental sample analysis will be reported, including the current status of development of the advanced techniques, their applications and future perspectives. (author)

[en] Splenocytes of wild-type (Prnp ^+/+) and prion protein gene-deficient (Prnp ^-/-) mice were treated with various activation stimuli such as T cell mitogen concanavalin A (ConA), phorbol 12-myristate 13-acetate (PMA) + ionomycin (Io), or B cell mitogen lipopolysaccharide (LPS). Cellular prion protein (PrP^C) expression was enhanced following ConA stimulation, but not PMA + Io or LPS in Prnp ^+/+ splenocytes. Rikn Prnp ^-/- splenocytes elicited lower cell proliferations than Prnp ^+/+ or Zrch I Prnp ^-/- splenocytes after LPS stimulation and showed sporadic nerve cells in the cerebral cortex and deeper structure. Around the degenerated nerve cells, mild vacuolation in the neuropil was observed. This neural alteration correlated well to the suppressed response of B cells in the spleen. The finding that discrete lesions within the central nervous systems induced marked modulation of immune function probably indicates the existence of a delicately balanced neural-endocrine network by PrP^C and PrPLP/Doppel