A determination method of the gamma-ray peak area and its uncertainty is described for a well-resolved single peak. The method needs no fitting the peak region, and the lower and the upper background regions to some analytical function such as the normal distribution function or the second degree polynomial, but instead, it fits a rectangular polygon to the peak region and a flat straight line to each background region, respectively. The peak area and its standard error are given by the rational expressions of counts and a set of some channel numbers in the peak region, and the lower and the upper background regions. An algorithm of these expressions is coded with BASIC laguage for a personal computer. An example of the peak area determination is shown for nine gamma-ray peaks of a152Eu source obtained by a high purity Ge detector.
Radiation characteristics of tritium plane sources have been studied for calibration of surface contamination monitoring instruments. On estimation of the radiation characteristics, three typical tritium sources of monomolecular layer, polymer and anodized aluminum were selected. Surface emission rates and energy distributions of the β-rays and X-rays emitted from the sources were measured using a windowless proportional counter. As a result, it turned out that the structural difference of sources influenced the calibration of instrument efficiency mentioned in ISO reports. And the suitable type of tritium source for routine calibration works was concluded. In addition, the efficiency of contamination source in the ISO reports was discussed for direct determination of tritium surface activity.
For the purpose of improving hygienic quality of white ginseng powders, the comparative effects of ethylene oxide (EO) fumigation and γ-irradiation (5 -10 kGy) on the sterilization, physicochemical properties and organoleptic quality were investigated. EO fumigation and γ-irradiation (5-10 kGy) completely eliminated the microorganisms contaminating in white ginseng powder. There was no growth of microorganisms after 7 months storage at 30°C and different relative humidities. In the physicochemical properties, ginseng saponins were considerably resistant to γ-irradiation (less than 10 kGy) and commercial EO fumigation, while sulfur-containing amino acids, reducing sugar and acidity were significantly changed by EO fumigation. EO residues were 570 ppm in the samples taken immediately after deaeration and 170 ppm in the stored samples of 8 days at 30°C, respectively. Ethylene chlorohydrin and ethylene glycol residues as the secondary products of EO were 9595 ppm immediately after deaeration and 221 ppm in the stored samples of 3 months at 30°C.
Since December 1992 to March 1994, we have performed myocardial imaging with123I metaiodobenzylguanidine (123I-MIBG) in 110 patients to examine myocardial sympathetic integrity. Among them 11 patients (10%) showed no accumulation of123I-MIBG in the heart. So we have examined the mechanisms of no myocardial123I-MIBG accumulation. 123I-MIBG imaging was obtained at 20 min and 3 h after intravenous injection of123I-MIBG (148 MBq) at rest. In addition to routine tomography, anterior planar imaging of the heart and the whole body imaging were performed. Eleven patients without myocardial123I-MIBG accumulation consisted of 5 patients with orthostatic hypotension (including 3 patients with diabetic neuropathy), four patients with hypertrophic cardiomyopathy (HCM), one patient with hypertension and one normal subject. In patients with orthostatic hypotension, standing test showed cardiac sympathetic dysfunction. In addition to no myocardial123I-MIBG accumulation, accumulation of123I-MIBG in the salivary glands was not found in all of them. These indicated that in patients with orthostatic hypotension, generalized sympathetic dysfunction caused no myocardial123I-MIBG accumulation. But in other 6 patients there was no evidence which suggested the cardiac sympathetic nerve dysfunction. Age, sex, serum norepinephrine level, myocardial perfusion and the medication were not different between the patients with and without myocardial123I-MIBG accumulation. So the mechanism of no myocardial123I-MIBG accumulation was not clear in these patients. But it was noteworthy that in patients with HCM, no myocardial123I-MIBG accumulation appeared in 17% (4/24), and the frequency of no myocardial123I-MIBG accumulation in HCM was significantly (p<0.05) higher than in other disease entities when patients with orthostatic hypotension were excluded.
As222Rn is an inert gas generated from226Ra in soils and rocks, 222Rn concentration in groundwater is higher than in river water. It is, therefore, possible to determine a section by measuring222Rn concentration in the stream where groundwater is seeping into the river. Moreover, the simultaneous equations of water balance and222Rn balance make it possible to quantify groundwater seepage and river water infiltration at the same time. However, as the222Rn loss in a stream is estimated directly by measuring the decrease in222Rn concentration in river water, the traditional method of analysis using222Rn is applied only to a river which has a section with no groundwater input. In this paper, the authors proposed a new method to analyze an exchange between river water and groundwater using222Rn which is applicable to a river in any condition. The222Rn loss in a stream was calculated assuming that a stagnant film existed at the boundary between water and air. Its thickness was estimated as 20μm from field investigations and the previous research. The method using222Rn was applied to the Omoi River Basin, Tochigi, and the groundwater seepage and the river water infiltration were quantified simultaneously. The obtained values were within reasonable ranges and the applicability of the method using222Rn was troved.
Hydrogen behavior in an Fe-Cr-Ni alloy is very important for the investigation of hydrogen embrittlement. This paper shows the hydrogen trapping sites in an Fe-Cr-Ni alloy, which have not been clarified with conventional techniques, using β-ray tracking technique. This technique, application of tritium TEM-ARG (transmission electron microscopic autoradiography) technique, is applied to the visualization of hydrogen trapping sites in a radiation damaged Fe-Cr-Ni alloy.