To improve the irradiation performance of vessel-and conveyor-type irradiators for effcient and uniform irradiation, a method for dividing a radiation source into two elements and putting the optimum source interval between them is proposed. With the increase in the source interval, the maximum dose rate in an irradiated material decreases slowly, while the minimum dose rate in the material and efficiency of the irradiation increase sharply and become maximum at the optimum source interval. Thereafter, the minimum dose rate decreases sharply. Consequently, the best irradiation efficiency and dose rate uniformity of the irradiation are obtained by putting the optimum interval between the source elements. The optimum source intervals and approximate formula are derived to make the optimum design of the source easy.
Two stereoisomers of empenthrin, (E) -1-ethynyl-2-methyl-2-pentenyl (1 R) -cis, trans-chrysanthemates, were regioselectively labeled with carbon-14 for use in metabolic studies on the characteristic ethynyl alcohol moiety. Action of ethyl [14C] formate (2) on ethylidenetri-phenylphosphorane gave the14C-formylated phosphorane (3) . Wittig reaction of 3 with propanal stereoselectively yielded the E isomer of 2-methyl-2- [1-14C] pentenal (4), which was derivatized to a crystalline imidazolidine (5) for purification. Regeneration of 4 from purified 5 followed by reaction with ethynylmagensium bromide gave (E) -1-ethynyl-2-methyl-2- [1-14C] -pentenol (6), the a-ethynyl alcohol of14C-labeled empenthrin, in 36% overall radiochemical yield from 2. Esterification of 6 with (1R) -cis- and (1R) -traps-chrysanthemoyl chlorides afforded the corresponding optically active [pentenyl-1-14C] empenthrins (1a and 1b) in good yields after chromatographic purification.
Under Na, K and Mg stress the elements distribution in the root and cotyledon of soybean was measured by neutron activation analysis. K and Na distributions showed more depletion than halogens or Mg, and root tip was more sensitive for the stress. About halogens, absorption of Cl was observed but depletion was shown only on Br. The depletion of Mg was highest for K stress than Na or Mg. Cotyledon accumulated higher amount of Mn and Ca under the stress of each elements, suggesting the buffering action of cotyledon for the environmental change.
An agar slice suspended culture was devised for the further study of the barley root. The roots were placed into an agar covered with a nylon cloth and suspended in a water culture vessel. Barley roots grown in the agar developed hardly any root hair. The element contents of the root grown in the agar culture and that in the water culture were measured by neutron activation analysis. The concentrations of K, Mg and C1 in the root grown in the agar were about half of these grown in the water. Na and Mn concentrations were the same and Ca concentration was slightly higher when grown in the agar. The agar system is expected to provide more information to study the root hair.
For instrumental neutron activation analysis (INAA) using short-lived nuclides with a TRIGA-II research reactor (100 kW), we renewed a pneumatic capsule transfer system. The new system consists of two sets of capsule loading and ejection ports and one irradiation point, thermal nentron flux of which is 1.5×1012n⋅ cm-2⋅ s-1. Selection of a capsule from the two ports and its starting and ending time of irradiation etc, are controlled with a personal computer (NEC PC-9801 m2), which displays all the information that is required for gamma-ray spectrometry with the GAMA system.
133Xe Gas concentration during the examinations of the lung ventilating scintigraphy using133Xe for three cases, was measured continuously by the flow type ionization chamber to estimate effective dose equivalent to the operator. The air flow distribution of the examination room was also measured for reference to examining the behavior of133Xe gas. The air around the patient lingers for few minutes or more. Based on the derived air concentration (DAC) in ICRP Publication 30, effective dose equivalent to the operator per examination was estimated to be 0.1-1.0μSv, which was lower than expected.