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  • Author or Editor: K. Nakamura x
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Abstract  

The rate constant of radiation induced exchange reaction between thallium(I) and thallium(III) ions has been studied for elucidating the mechanisms which are responsible for (T1(II) intermediates or bridging groups (SO 4 2– ) in sulfuric acid and perchloric acid solutions. It was found that the radiation induced exchange reaction is accelerated by the sulfate ion, and the rate of the thallium(II)-thallium(I) reaction is faster than that of the thallium(II)-thallium(III) process in perchloric acid solution.

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Abstract  

The substoichiometric separation of Yb(III) can be achieved by the extraction of a substoichiometric amount of thenoyltrifluoroacetone and an excess amount of phenanthroline in benzene. The appropriate pH range for the substoichiometric extraction is 6–8. The reproducibility of the substoichiometric extraction of Yb(III) is very good as RSD 1%. As an example, Yb in a manganese nodule is determined by the substoichiometry combined with the radioactivation analysis. The content of Yb is 17.63±0.23 g/g. The present procedure can be applied to the determination of other rare earth elements.

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Abstract  

The extraction behavior of Eu(III) has been studied using di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA, HA) in kerosene. Europium was extracted as Eu(HA2)3 with the extraction constant of 2.0·10–3. This extraction system was applied to the transport of Eu(III) across a DTMPPA liquid membrane supported on porous polytetrafluoroethylene. Europium was quantitatively moved through the liquid membrane containing 0.1M (HA)2 as a mobile carrier from the feed solution of pH above 3 into the product solution of 0.1M HNO3, yielding a concentration factor of ten. The transport rate increased with increasing pH and DTMPPA concentration.

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Abstract  

Acetanilide and para-substituted acetanilides were tritiated by heating with HTO in the presence of RhCl3.3H2O as a catalyst in an N,N-dimethylformamide solution at 105–107°C for 18 h. Under such conditions, tritium introduced into the anilide molecules was found at the adjacent ortho positions to the acetamido group with virtually 100% regioselectivity. The substituent effect on the rate of tritiation was observed.

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Abstract  

Transport of La, Nd, Eu, Tb, Tm and Lu through a supported liquid membrane (SLM) was investigated by using di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA) as a mobile carrier. Lanthanoid elements in the feed solution were quantitatively transported and concentrated into the product solution of mild acidity. The transport rates increased with increasing atomic number of lanthanoids in the low pH region of the feed solution. Separation factors evaluated from the transport rates for lanthanoids were close to those from the distribution ratios in liquid-liquid extraction.

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Abstract  

The curing agents of epoxy resin, trimethylsilyl ethers of phenol novolak (TMSPN) and cresol novolak (TMSCN) were prepared by refluxing phenol novolak and cresol novolak respectively, with the mixture of hexamethyldisilazane and chlorotrimethylsilane in THF. The curing reaction of epoxy resin with these curing agents and the thermal properties of cured resins were examined. The Tg values of epoxy resins cured with TMSPN were a little higher than those cured with TMSCN. The maximum of Tg is 118C for TMSPN-cured epoxy resin against 112C for TMSPN-cured epoxy resin. The water absorption of hydrophobic epoxy resins cured with TMSPN was a little lower than those cured with TMSCN. The clear decrease of water absorption is attributed to the difficulty of the micro-void formation caused by the more tight primary structures of TMSPN. The water absorption at 25C containing trimethylsilyl groups is about one-tenth of that of epoxy resins cured with conventional curing agents and even one-half of that of the epoxy resins cured with active esters. The low water absorption is attributed to the presence of trimethylsilyl groups, which are more hydrophobic than ester groups, and to the absence of hydroxyl groups of the cured resins.

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Abstract  

Neutron activation analyses were performed for the newly issued reference rocks, GSJ JA-1 and JB-2, and also for the widely distributed GSJ JG-1 and JB-1. The contents of fourteen elements could be newly determined for the former two rocks and those of eleven elements were re-determined for the latter rocks.

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Abstract  

Phase transition process of polyester from phenanthrene, poly(oxyheptamethyleneoxy-2,7-phenantrenedicarbonyl), a main chain type liquid crystalline polymer, was investigated by simultaneous DSC-XRD measurements using the synchrotron radiation facility (PF). Three exothermic DSC peaks were observed during cooling from the isotropic liquid state. These DSC peaks were assigned to the transition from the isotropic liquid to the smectic A, that from the smectic A to C, and that from the smectic C to the crystalline state, respectively, as determined by XRD profiles. The rate of transition from the smectic A to C was very slow compared with the liquid crystalline transition and the crystallization. From the DSC-XRD results, the thermal expansion along c-axis in the crystal and smectic phases are 4.110−4 and 1.410−3 nm K−1 , respectively.

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