Plutonium isotopes and 137Cs in Dolon settlement near the Semipalatinsk Nuclear Test Site: About 50 years after the first nuclear weapon testing

Recent controversies concerning the radiation doses for populations living in the village of Dolon due to the nuclear explosions carried out at the Semipalatinsk Nuclear Test Site (SNTS) have encouraged us to evaluate in more detail the levels and distributions of residual long-lived radionuclides¹³⁷Cs and Pu isotopes (²³⁸Pu,^239,240Pu) in soils within the village. Soil core samples up to a depth of about 30 cm and/or 100 cm were collected at 25 sites and subjected to analysis of ¹³⁷Cs and Pu isotopes. The inventories of ¹³⁷Cs and ^239,240Pu were found to be in the wide range of 790-10,310 and 530-14,320 Bq/m², respectively. Sequential leaching of Pu from the soil showed that more than ca. 80% of the ^239,240Pu was not leached by hot digestion with conc. HNO³ + H₂O₂, indicating the presence of Pu associated with fused silicates. Further, the presence of hot-particles from the Pu contaminants by a-track radiography technique using CR-39 polycarbonate was confirmed in the soil, even at present, after about 50 years from the first nuclear weapon testing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)(n)() (n = 2 or 3)

A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)(2) in acetic acid at 100 degrees C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their alpha-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (k(H)/k(D)) in the oxidation of ethylbenzene and ethylbenzene-d(10) with dioxygen using NHPI/Co(acac)(2) was 3.8.     

Geochemical record of U and Th isotopes in bottom sediments of Lake Kawaguchi at the foot of Mt. Fuji, Central Japan

Sediment cores from Lake Kawaguchi at the foot of Mt. Fuji in Japan were analyzed for U and Th isotopes (²³⁸U, ²³⁴U, ²³²Th, ²³⁰Th and ²²⁸Th) in the light of the linkage to paleoenvironmental changes. These isotopic concentrations and their ratios varied widely with depth of sediment core. A marked disequilibrium (1.1–1.5) higher than the value of 1.0 was observed for ²³⁴U/²³⁸U activity ratios, indicating that U from lake water with high ²³⁴U/²³⁸U ratio (ca. 1.6) was transferred to the bottom sediment by adsorption and/or adhesion onto the settling particles. By using model equations, the U found in the sediment core was separated into lithogenous and autogenous U fractions. These depth profiles were compared with parameters such as organic matter and biogenic-SiO₂ contents and amount of rainfall. Some variations of selected parameters with depth coincided with those of lithogenous or autogenous U. The results obtained suggest that variation in the lithogenous and/or autogenous U in the sediment with depth might be helpful in tracing the geochemical behavior of U and the past environmental changes in the area surrounding Lake Kawaguchi.The authors would like to express their gratitude to Dr. Y. Ohtsuka of Department of Radioecology, Institute for Environmental Sciences and Dr. K. Sasaki of Department of Cultural Properties and Heritage, Kanazawa Gakuin University for sampling of water and rock samples at Lake Kawaguchi.     

Local distribution of radioactivity in tree leaves contaminated by fallout of the radionuclides emitted from the Fukushima Daiichi Nuclear Power Plant

We analyzed fresh and dead leaves collected in forests in Fukushima after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, using autoradiography. Both fresh and dead leaves of Cryptomeria japonica were contaminated by radionuclides (¹³⁴Cs and ¹³⁷Cs). Contamination of the fresh leaves was possibly attributed to interception of radionuclides by tree canopies, whereas the dead leaves indicated the direct deposition of radionuclides by fallout and/or washout of radionuclides intercepted by tree canopies. Translocation of radiocesium from a contaminated branch to new leaves growing after the FDNPP accident was not clearly observed, although transfer of radiocesium from leaf parts to male flowers occurred. Fallen leaves of Quercus serrata, which started growing after the FDNPP accident, did not show radioactivity, indicating that significant amounts of translocation from other parts to new leaves did not occur. Fallen leaves of Q. serrata collected from a litter showed hot spots originating from direct fallout. Needles of Pinus densiflora were also contaminated by fallout. Leaching with pure water removed soluble fractions of radiocesium and hot particles from the surface of the contaminated leaves, but significant amounts of radioactivity remained. This means that foliar absorption occurred in both fresh and dead leaves. Further leaching experiments using surfactant and acetone could not remove the remaining radiocesium from the leaves. The leaching experiments indicate that radiocesium in the contaminated leaves is strongly fixed in leaf tissues and is not readily released unless leaf tissues are decomposed.     

A Dual Functional-Group Derivatization Liquid Chromatography–Tandem Mass Spectrometry Method: Application for Quantification of Human Insulin

Chromatographia - Recently, we developed a sensitive and accurate quantification method for short-chain peptides using dual functional-group derivatization. Sensitive and accurate quantification...     

Dominant Li+ ion conduction in Li+/Na+ mixed crystal, 15NaI∙LiBH4

Journal of Solid State Electrochemistry - In the present work, the conduction ions in 15NaI∙LiBH4 are investigated by secondary ion mass spectroscopy (SIMS) and galvanostatic measurements. An...     

Isotopic dependence of the giant monopole resonance in the even-A 112-124Sn isotopes and the asymmetry term in nuclear incompressibility

The strength distributions of the giant monopole resonance (GMR) have been measured in the even-A Sn isotopes (A=112-124) with inelastic scattering of 400-MeV alpha particles in the angular range 0 degrees -8.5 degrees . We find that the experimentally observed GMR energies of the Sn isotopes are lower than the values predicted by theoretical calculations that reproduce the GMR energies in 208Pb and 90Zr very well. From the GMR data, a value of Ktau = -550 +/- 100 MeV is obtained for the asymmetry term in the nuclear incompressibility.     

Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method

Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the (n,L)=(37,35) state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure arising from the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of nu(+)(HF)=12.895 96+/-0.000 34 GHz and nu(-)(HF)=12.924 67+/-0.000 29 GHz agree with recent theoretical calculations on a level of 6x10(-5).     

Primary populations of metastable antiprotonic (4)He and (3)He atoms

Initial distributions of metastable antiprotonic (4)He and (3)He atoms over principal (n) and angular momentum (l) quantum numbers have been deduced using laser spectroscopy experiments. The regions n = 37-40 and n = 35-38 in the two atoms account for almost all of the observed fractions [(3.0 +/- 0.1)% and (2.4 +/- 0.1)%] of antiprotons captured into metastable states.