The nanosecond pulse radiolysis technique has been applied to study the rate constants for charge transfer and substitution reactions of radical ions. Electron transfer from biphenyl anion to styrene derivatives shows a correlation with the reduction potential of the acceptors expected from the Marcus theory. The positive charge transfer from biphenyl cation to the same acceptors shows a much larger rate constant, suggesting a considerable shift of the free energy relationship to the positive side of Go. The substitution reaction of fluorenone anion with organic halides shows an SN2 character, while that of diethyl fumarate shows electron transfer nature. The dimerization of radical anions has been proven for benzophenone and fluorenone, when their lifetime of the parent anions are prolonged by countercations.
We investigated the influence of ionic strength on migration behaviors of Sr and Eu in the presence of humic acid (HA). The
breakthrough curve of Sr through a quartz sand column in the presence of HA was identical to that in the absence of HA. Europium
migration in quartz sand was enhanced by the presence of HA at low ionic strength. At high ionic strength, Eu migration in
the presence of HA was hindered compared to that in the absence of HA. Adsorption of europium on quartz sand in the absence
of HA decreases with increased ionic strength.
Authors:C. Mothé, C. de Araujo, M. de Oliveira, and M. Yoshida
Polyurethane composites with bagasse of sugar cane (BSC) at different proportions: 5, 10 and 20 mass/mass% were prepared by
melt mixing method. The thermal behavior of these composites were studied by thermogravimetry (TG/DTG). The influence of fiber
concentration on the kinetic parameters of the composites was studied and a better interaction was suggested between PU/BSC
with 5mass/mass% of fiber. Scanning electron microscopy was carried out to investigate surface morphology.
Authors:K. Minewaki, T. Kato, H. Yoshida, and M. Imai
We have investigated effects of shear flow on the structure of lamellar phase in hepta(oxyethylene glycol)—n—hexadecylether—water system using small-angle neutron scattering (SANS) under shear flow at the shear rates (
=10–2 ~1 s–1, significant changes have been observed in both intensity and position of the reflection peak. Small-angle X-ray scattering without shear has been also measured at various concentrations and temperatures. It has been suggested from these results that the shear flow causes contraction of lamellar domains and formation of a new domain composed of disrupted bilayers which grows rapidly with increasing shear rate and reconstructs original microstructures.
Authors:M. Yoshida, S. Sumiya, H. Watanabe, and K. Tobita
A rapid separation method was developed for determination of low level promethium-147 and samarium-151. The rapid method, applied to environmental samples, provided speed and efficiency for the respective separation of Pm and Sm from other lanthanides with the simplified technique of high performance liquid chromatography (HPLC) system. The separation time of Pm and Sm in HPLC separation was shortened by stepwise eluent method of -hydroxyisobutyric acid as compared with a gradient eluent method of lactic acid with HPLC despite increase in sample volume for significant determination of Pm-147 and Sm-151. This method permitted the detection limit around 0.1 Bq/kg-dry-soil for Pm-147 and Sm-151 in 200 g soil sample by counting for 500 min with a liquid scintillation counter.
Authors:D. Ishii, T. Yamada, M. Nakagawa, T. Iyoda, and H. Yoshida
Summary Thermally induced structural transformation of fibrous hydrogen-bonded molecular assemblage formed from an amphoteric pyridinecarboxylic acid of 6-[2-propyl- 4-(4-pyridylazo)phenoxy]hexanoic acid (C5PR) was studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetry (TG). The organized fibrous morphology formed in an aqueous solution was stable at temperatures below 150°C. The ordered crystalline solid phase (K1) of the original fibrous material altered to a disordered crystalline solid phase (K2) at 150°C and subsequently to an isotropic phase (I) at 172°C. In the isotropic state, the C5PR molecule was slowly decomposed by decarboxylation. Once the molecular assemblage was subjected to the mesophase by heating, another ordered crystalline solid phase (K3) appeared reversibly at 17°C. The heat budget analyses by DSC indicated that a conformational entropy change such as the side-chain propyl group and the main-chain pentamethylene unit in the hydrogen-bonded molecular assemblage took place between the two ordered crystalline solid phases K1 and K3.
Authors:Y. Muramatsu, S. Yoshida, T. Ban-nai, and M. Akashi
For three heavily exposed workers in the Tokai-mura criticality accident, the levels of 24Na, 42K and 82Br were measured in blood, urine, vomit and hair. 24Na showed the highest activity and was found to have a specific activity of 8.24·104, 4.34·104 and 1.23·104 Bq 24Na per g Na in blood of the three exposed workers. Based on these data the individual neutron fluences were calculated. Radionuclides
were also measured in environmental samples from the JCO campus. The fission products 131I, 133I, 140Ba-140La and 137Cs were determined in plant samples and the activation products 59Fe, 46Sc, 60Co and 152Eu were identified in soil samples. 235U/238U ratios in soil and plant samples were measured by ICP-MS.
Authors:D. Ishii, T. Yamada, M. Nakagawa, T. Iyoda, and H. Yoshida
thermally induced structural transformation of a hydrogen-bonded crystal formed
from an amphoteric molecule of 6-[2-methoxy-4-(pyridylazo)phenoxy]hexanoic
acid MeO was studied using differential scanning calorimetry (DSC), Fourier
transform infrared spectroscopy (FTIR) and X-ray diffraction measurement (XRD).
Crystal form of the hydrogen-bonded crystal was measured by single crystal
four circle diffractometer (Mo-Kα radiation). As
a result, the crystal of MeO was stabilized by many C–H⋅⋅⋅O hydrogen
bonds, and the C–H⋅⋅⋅O hydrogen bonds were broken by thermal energy
reversibly. After transformation the supramolecular architecture was composed
of supramolecular polymer including free-rotation pentamethylene main chains.
Authors:M. Arisaka, T. Kimura, H. Suganuma, and Z. Yoshida
Coordination states of Eu(III) in anion exchange resin (AG 1X8) systems with LiCl-H2O/alcohol mixed media were determined from the luminescence lifetimes and the emission spectra of Eu(III). The sorption equilibrium of Eu(III) was discussed on the basis of the correlation between the distribution coefficients and the coordination states in the solution and resin phases. The sorption of Eu(III) was mainly caused by the formation of an anionic Eu(III)-chloro complex in the resin phase, which was enhanced by the decrease of 'free' water activity due to the addition of alcohol. The effect of ethanol added was larger than that of methanol.