No abstract available

[en] The radiation resistances of the bioburden of cut-gut sutures filled with isopropyl-alcohol solution (IPA) were studied. In order to maintain the reliability of delivered doses, Ceric-cerous dosimeters (the facility standard) were calibrated with NPL alanine dosimeters and uniform dose rate areas in the gamma irradiation field were established. The doses measured for 3 batches by a Ceric-cerous dosimeter were equal to the difference within an accuracy of ±2% and the measured doses between Fricke-dosimeter and Ceric-cerous(E98) dosimeter agreed within about 2.3%. Recovery methods of natural bioburden from the sutures were validated by a double filtration method. Reciprocal-shaker treatment showed high recovery deficiency for the bioburden. The bioburden consisted of 5 types of spore forming bacteria and the most radiation-resistant strain was identified as Bacillus megaterium, which occupies 6.1% of all (473 isolates). The radiation-resistances of the bacteria were 2.33 kGy in IPA solution and 2.15 kGy in dried TSB. Using the distribution of radiation-resistance of the bioburden, the doses required for 10^-2 or 10^-6 SAL were calculated. It was found that ISO Method 1 gives a higher 10^-6 SAL dose in spite of a lower 10^-2 SAL dose at over 0.56 of average bioburden, compared with these for the suture. (author)

[en] Chicken meat with bone was irradiated by gamma rays at -19 - 10degC. Both amounts of hydrocarbons formed from fatty acids and intensity of ESR signals in bone fragments were measured. Very good correlation was found between the amount of hydrocarbons and the intensity of ESR signals. The amount of hydrocarbons (C_n-2:1), having 2 carbon atoms less than the original fatty acids and an additional double bond, was almost constant irrespective of the irradiation temperature. The amount of hydrocarbons (C_n-1:0), having 1 carbon atom less than the original fatty acids, increased as the irradiation temperature raised. As the ratio between corresponding fatty acids, the ratio between hydrocarbons (C_n-2:1) is a suitable index in the detection of the irradiation. On the contrary, the ratio of hydrocarbons from the same fatty acid, (C_n-2:1)/(C_n-1:0), varied according to the kind of fatty acid and irradiation temperature. It was found that under the irradiation temperature of -19 - 10degC, the intensity of ESR signals of bone is not affected by the irradiation temperature. (J.P.N.)

[en] We examined postembryonic effects after helium ion and gamma ray irradiation of an isolated whole flower (a flower with pedicel) of Brassica napus through a flower organ culture, and estimated the effects of irradiation on embryogenesis in sexual reproductive stages. The whole flowers were irradiated with 30 Gy of helium ions and gamma rays in the early globular embryo and/or torpedo embryo stages. The helium ion and gamma ray irradiation of early globular embryos caused some drastic malformations in the first true leaves. Those malformations were classified into four types: cup-shaped, funnel-shaped, shrunk and the other varied leaves. The types were observed in 40% of plants that developed first true leaves. Both cup-shaped and funnel-shaped types were observed in over 15%. On the other hand, the irradiation of gamma rays of torpedo embryos caused sectors lacking chlorophyll in first true leaves. (author)

No abstract available

[en] A new method of radon measurement, absorptive polymer dissolved liquid scintillation counting, was developed. A polystyrene foam absorber which absorbed radon was dissolved in liquid scintillator, and the radioactivity was measured. This measurement has merits in that, (1) a solid state absorber has no chemical hazard, and is easy to treat, (2) the absorber itself is easily dissolved in liquid scintillator, and maintains ideal condition for liquid scintillation counting. The measurement will be available for liquid state or gas state. The time to reach equilibrium was 24 hours for a cross section 10 x 10 mm polystyrene foam. Absorbed radioactivity was proportional to the mass of polystyrene foam and to the partial pressure of radon. Absorbed radon activity of polystyrene foam was 130 fold that of water, or 2.6 fold that of toluene. Although the accuracy is less than the toluene extraction method, quantitative measurement is suitable not only to radon but to other radioisotope gases. (author)

[en] Simple measurement methods of C-14 contents in natural materials are studied. Three methods, 1) measuring by liquid scintillator dissolved sample directly, 2) measuring by liquid scintillator mixed with aqueous solution of sample, 3) measuring by liquid scintillator dissolved bicarbonate produced from sample by combustion, are examined. As a result, the first and second methods have merit of simple handling, but have faults of application to limited samples and variable accuracy of C-14 contents for each sample. The third method is more complex than the others, but has stable accuracy of C-14 contents for many samples. Carbon-14 contents of organic materials excavated from relics are measured by the third method and the ages of the materials are estimated by the C-14 contents. (author)

[en] The dual ion implantation of silicon and carbon into copper (99.9%), iron (99.9%), SKD11 steel and SUS304 austenitic stainless steels was carried out with a MeV energy ion accelerator. The cross-section of the implanted layer were observed with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The surface layers of the implanted substrates were investigated with X-ray photoelectron spectroscopy (XPS) and a transmission electron microscope (TEM). The hardness of the samples was tested with a nano-indentation. It was found with XPS Si (2p) spectra and TEM that a part of the Si ions and C ions formed an amorphous layer of SiC, carbide and metals by dual ion-implantation. The hardness of the dual ion-implanted steels were improved. The mechanism of hardness was suggested by cross-sectional TEM images. (author)