Using electron spin resonance (ESR) spectroscopy, we revealed the presence of four radical species in γ ray irradiated ginseng (Agaliaceae) . The representative ESR spectrum of ginseng is composed of a sextet centered at g=2.0, a sharp singlet at the same g-value and a singles at g=4.0. The first one is attributable to a hyperfine (hf) signal of Mn2+ion (hf constant: 7.4 mT) . The second one is due to an organic free radical. The third one is originated from Fe3+. Upon γ ray irradiation, a new ESR signal was detectable in the vicinity of g=2.0 region. The progressive saturation behaviors of the ESR signals at various microwave power levels were indicative of different relaxation of those radicals. Thus, ESR method clarified four independent radical species in the irradiated ginseng. The anisotropic ESR spectra were detected upon angular rotation of the sample tube. This is due to the existence of anisotropic microcrystal in the ginseng powder sample.
The activity concentrations of natural (226Ra, 232Th and40K) and anthropogenic (137Cs) radioactive elements in local and imported wood samples have been investigated during the last few years. Seven local and four imported wood types were measured. The activities of the natural isotopes in both local and imported wood samples were comparable. The Chernobyl accident didn't only affect European countries through contamination of the forested areas but also non-wood producing countries like Egypt. A fraction of the deposited fallout radionuclides has become incorporated into wood. Most of the imported samples (-83%) showed measurable concentration of137Cs. The average137Cs activity levels in local and imported wood were 0.16 and 2.75 Bq/kg dry weight, respectively. The result of this study has its importance to many other woodimporting countries.
A preliminary study of radon concentration in the air was carried out in a tunnel under construction over three different sampling periods from June 2001 to August 2002. The concentration was measured with LR-115 Type II nuclear track etch detectors and E-PERM detectors. The average radon concentrations for each sampling period were : 1082 Bq m-3, 1550 Bq m-3and 414 Bq m-3. Possible formation of convection cells inside the tunnel can explain the variation of radon concentration. A dose assessment calculation was carried out to estimate the effective doses of the construction workers. The maximum effective dose was estimated at 13.5 msv y-1for an eight-hour shift.