In several decades, iron (II) bromide (FeBr2) has been investigated as a typical Ising-type antiferromagnet by several kinds of experimental techniques. By the Mössbauer measurements, it was normally observed that only the magnetic spectrum appeared just below Néel temperature in FeBr2. However, we found the anomalous spectra, in which paramagnetic component coexisted with magnetic one near Neel temperature. For two kinds of single crystal FeBr2samples, IM and IIM, we determined the Mössbauer parameters of the observed spectra by the computer analyses : the relative absorption intensity Ip of the paramagnetic component to the total absorption area of the best fitting spectrum and the value of the hyperfine field Hhf of the magnetic component and values of the quadrupole splitting 1/2⋅e2gQ of the magnetic and the paramagnetic components. The temperature variation of Hhf is unique and the same as that observed for the sample in which the anomaly was not found. The fact means that the spins in the paramagnetic component behave as if they have just one Néel temperature, when they go to the magnetic state. It is found that the coexisted paramagnetic component does not indicate the distribution of Néel temperature. The temperature range of the coexistence spreads over -2 K for the sample I M and -0.4 K for the sample IIM, indicating that the sample IIM is purer than the sample IM. It was clarified microscopically that the anomaly appeared larger in the less pure sample. That is consistent with the results obtained macroscopically in the magnetization and ac-susceptibility measurements. FeBr2is known that some stacking faults are apt to be formed in the system. We consider that the anomalous phenomenon was caused by the anomalous exchange couplings resulted by the stacking faults those gave the anomaly to the normal antiferromagnetic interactions.
Hybridization of a thermo-responsive N-isopropylacrylamide (NIPAAm) hydrogel with poly (vinyl chloride) (PVC ) has been studied in order to improve its mechanical property without compensation for its functionality. In this study, a simultaneous radiation grafting method was applied to the hybridization. In an aqueous solution containing NIPAAm monomers without contacting to PVC, effective radiation-induced polymerization of NIPAAm was achieved. In the presence of a PVC film, graft polymers composed of PVC and NIPAAm was obtained. The graft polymers manifested the thermo-responsive deformation repeatedly.
Since sorghum plant (Sorghum bicolor L.) has a big potential to be cultivated in Indonesia especially in drought prone areas, improvement of sorghum had been carried out through mutation breeding methods. The seeds of the sorghum plant was irradiated by gamma rays emitted from cobalt-60 source. The total dose was 0.4 kGy. Through selection process in the M2 generation, a number of promising mutant lines of sorghum have been obtained and registered in the M3 generation. In the M4, a number of 100 mutant lines were tested against drought in Gunung Kidul District during the dry season in 2000. Results of the test showed that mutant line DU/20/Psj/1, DU/20/Psj/4, DU/20/Psj/24, JA/30/Cty/21, ET/40/Psj/4 and DU/20/Psj/10 had relatively high grain yield compared to the control variety.
Accumulation and excretion of85Sr in goldfish, Carassius auratus auratus, rearing in the radioactive freshwater were investigated in order to elucidate the accumulation mechanism of90Sr in naturally living fishes. The accumulation of85Sr, expressed in concentration ratio (CR) between fish and water, in whole body of the fish showed a increasing tendency with the rearing time, and the CR value reached 5.4±0.4 (mean±standard error) at 7th day. On the other hand, the excretion of85Sr, expressed in retention rate, in whole body rearing in non-radioactive freshwater following the accumulation above for 7 days demonstrated a rapid decreasing at first few days, and then a gradual decreasing tendency indicating the biological half lives about 4 days and 205 days, respectively. The retention rate resulted in nearly 75% of initial radioactivity, i. e. 25% of excretion, at 25th day. As for the tissues and organs, the CR values of85Sr reared in the radioactive freshwater for 7 days were 62.3 (vertebra : bone), 31.1 (scale), 12.5 (gill), 0.6 (viscera) and 0.4 (muscle) . On the other hand, higher excretion was found in the viscera and the muscle than that in the bone, the scale and the gill. It is so suggested that the metabolic turnover rate of this radionuclide is different among these tissues and organs particularly characterizing higher accumulation and lower excretion in the vertebra (bone) and scale.
This paper described experiments on the adsorption of radon gas on surfaces of various materials. The experiments were carried out on three kinds of materials : Poly (vinyl chloride), polyethylene and stainless steel. On stainless steel, adsorption was not detectable. On the other hand, there was clearly adsorption on poly (vinyl chloride) and polyethylene. A poly (vinyl chloride) sheet of one square meter surface in a 5.3 L container absorbed approximately 20% of the radon. Radon adsorption has to be taken into account when radon concentration measurements in the air.
In order to the practical use of radicidation of beet red, natural food colorant with low heat stability and high possibility of microbe contamination, we studied on the energy dependency and dose rate effect for the influence on functional properties of the beet red colorant. For the elucidation of energy dependency, the γ-ray (1.33 MeV) and electron beams with different accelerating voltages (0.75, 1, 2.5, 5 and 10 MeV) were used. The dose rate effect was studied under the different dose rate by using γ-ray (0.723, 1.91 and 4.55 kGy/h) and electron beams with accelerating voltage of 10 MeV (1.0×103, 2.6×103, 7.0×103, 2.0×104 and 5.0×104kGy/h) . The results obtained in this study showed that regardness of these energy and dose rate, the functional properties o f the beet red colorant were little affected by irradiation less than 25 kGy of ionizing radiations.