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Abstract  

We report the temperature dependence of Mössbauer spectra of a mixed-valence dinuclear Fe(II) Fe(III) complex, [Fe2(bpmp)(Ph(CH2)2COO−)2](BF4)2 1, where Hbpmp represents 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol. Two quadrupole doublets observed at 78 K approach each other as the temperature is increased. The two high-energy components of a doublet due to Fe(II) and of that due to Fe(III) become broad in the temperature range from 78 to 230 K and then become narrow above 260 K. The temperature dependence of the spectra was interpreted by assuming of intramolecular electron exchanges between two energetically inequivalent vibronic states FeA(II)FeB(III) and FeA(III)FeB(II) where one of them is slightly more stable than the other.

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Abstract  

Concentrations of239+249Pu in environmental samples were detemined by ICP-MS and spectrometry, showing consistent results, which suggests an applicability of ICP-MS to239Pu and240Pu measurement. The activity ratios of238Pu/239+240Pu and240Pu/239Pu were significantly different in samples from the general environment and near Sellafield reprocessing plants, indicating the usefulness of these ratios for identification of the Pu contamination source.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Osaki, Y. Tagawa, T. Chijiiwa, S. Sugihara, and Y. Maeda

Abstract  

The35S content in atmospheric deposition, aerosol and rain water was determined about every 10 days for a year with7Be,32P and some stable elements. Average35S concentrations were 110 mBq·m−2·d−1 for atmospheric deposition, 0.078 mBq·m−3 for aerosol in surface air and 45 mBq·l−1 for rain water. The ratios of7Be/35S were abnormally low, although most of32P/7Be showed the reasonable values corresponding to the residence times from 10 to 60 days. The excess35S suggests an external source of35S or/and a faster cycle of35S than that of7Be and32P.

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Abstract  

The dry deposition rates on various grass fields and two forests have been measured by the use of 212Pb (T 1/2 = 10.6 hours). The deposition rate on grass fields (average: 7 mm·s−1) roughly depends on the logarithms of the heights or densities of the grasses. The dry deposition rates on a broadleaved forest (Lithocarpus edulis) and a coniferous forest (Cryptomeria Japonica) were also measured. The highest (ave. 26 mm·s−1) was on the forest of C. Japonica because of the dense and adhesive surfaces of the leaves.

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Abstract  

Fall water, stem flow water and falling litter in a coniferous forest (C. japonica) and a broad-leaved forest (L. edulis), and rainwater on a grassland near the forests were collected, and their 7Be and 210Pb contents were measured. The average residence times of 7Be and 210Pb in the forest crowns were calculated from the balances of their radionuclides, those in the forest crown of C. japonica were 88 days for 7Be and 9.2 years for 210Pb, and those in the forest crown of L. edulis were 52 days and <1 year, respectively.

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Abstract  

The enthalpies of dilution of aqueous solutions of methanol, ethanol, l-propanol, 2-propanol, 1-butanol, l-pentanol, 1-hexanol, cyclohexanol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol and poly-alcohol(cyclohexaamylose) have been determined at high dilution as a function of the mole fraction of alcohol at 298.15 K, by a rocking twin-microcalorimeter of the heat-conduction type. A smoothing equation of the enthalpies of dilution against the mole fractions of alcohols are given. The graphical comparison of experimental results with their smoothed values or literature ones, taking into account the dependence of the mole fractions, are also presented. It has been found for the aqueous solutions of shorter n-alcohols than hexanol that at very high dilution, exothermic values of molar enthalpies of dilution from a definite mole fraction of alcohols to infinite dilution with the change of mole fraction is proportional to carbon number of n-alcohols. The molar enthalpies of infinite dilution of aqueous butanediol isomers and 1-hexanol were very large. Molar enthalpies of infinite dilution of aqueous poly-alcohol (cyclohexaamylose) were endothermic.

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Summary  

Iron(III) spin-crossover complexes [Fe(pap)2]ClO4 . H2O (1), [Fe(pap)2]BF4 . H2O (2), [Fe(pap)2]PF6 . CH3OH (3), [Fe(CH3-pap)2]ClO4 . H2O (4), [Fe0.5Al0.5(pap)2]ClO4 . CH3OH (5) and [Fe0.25Al0.75(pap)2] ClO4 . CH3OH (6)were prepared andthe spin transition behaviors of the complexes have been studied from magnetic susceptibility and Mössbauer spectroscopy measurements. The magnetic properties of light-induced metastable state are measured using Hg-Xe light source. T 1/2is temperature at which the populations of the high-spin and low-spin species are fifty-fifty. Metastable HS is produced by light irradiation at 5 K. T(LIESST) is the temperature at which the populations of the metastable high-spin species decrease to one half and cooperativity factor Cis defined as the parameter which presents the strength of cooperativity. The value of T(LIESST) decreases as T 1/2increases and the plots of T(LIESST) vs. Cshow linear correlation. The effect of cooperativity of the complexes on the relaxations in solid was confirmed for the iron(III) complexes.

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Abstract  

Depth distribution of atmospheric 210Pb and 7Be and 90Sr and 137Cs fission products was measured in two types of aeolian soils (desert dust and volcanic ash), irrigated paddy soil and strongly acidic soil. The depth dependence of 210Pb, 7Be and 137Cs show that these radionuclides have been diffused as solid soil particles in surface soil layers. In aeolian soil layers, about 50% of 90Sr were diffused in surface soil layer and the remaining 50% had penetrated to deeper layers. The half of the fission particles containing 90Sr were shown to have decomposed over the past 35 years.

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Abstract  

A rapid and sensitive method for the neutron activation analysis of selenium, arsenic, and antimony is described. These elements and their compounds present in rocks and sediments were simultaneously evolved as their gaseous bromides from sodium bromide-strong phosphoric acid medium only by heating the irradiated samples in the medium. The evolved gas was absorbed in an appropriate absorption solution and then each element was finally recovered as metals for selenium and arsenic, and as sulphide for antimony. The preferable conditions for the distillation and for the separation of these elements are discussed. The method thus established was applied for the activation analyses of rocks and of river sediments, and profitable data were obtained.

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Abstract  

Variation of tritium concentration was examined for 100 days in the course of degradation of fresh pine needles, which were left on a pine forest floor. No difference was observed on free water tritium (FWT) and organically bound tritium (OBT) concentrations of sterilized samples by gamma-ray irradiation or fumigation and control samples, attributable to incomplete sterilization. The OBT concentrations did not increase within the experimental period as the level of humus collected from the forest floor. The results suggest that a longer degradation time, more than 100 days, is necessary to elevate OBT up to the level, which is observed in the general environment.

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