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Abstract  

Binding constants of Eu(III)- and Am(III)-complexes with soil-derived humic acid were determined by solvent extraction at various pH and ionic strength. Based on the dependence of binding constants on pH and ionic strength, stabilities of the humate complexes in land water and seawater were estimated. Speciation calculation based on the binding constants indicated that Am(III) could combine with humic substances in natural water system.

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Abstract  

Extracton, of Am3+ in benzene with 2-thenoyltrifluoroacetone (HTTA) and crown ethers (CEs) such as 15-crown-5, 18-crown-6, dicyclohexano-18-crown-6, dibenzo-18-crown-6, dicyclohexano-24-crown-8, and dibenzo-24-crown-8 was investigated. Synergistic effect by CE was observed regardless of the kind of CE examined. The extracted species was found to be Am(TTA)3(CE), and adduct formation constants between Am(TTA)3 and CE in the organic phase were determined. The sequence of constant could not be explained only by basicity of CE and the steric effect of CE should be taken into account to elucidate the adduct complex formation.

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Acta Biologica Hungarica
Authors: Kanako Aono, A. Fusada, Y. Fusada, W. Ishii, Y. Kanaya, Mami Komuro, Kanae Matsui, S. Meguro, Ayumi Miyamae, Yurie Miyamae, Aya Murata, Shizuka Narita, Hiroe Nozaka, Wakana Saito, Ayumi Watanabe, Kaori Nishikata, A. Kanazawa, Y. Fujito, R. Okada, K. Lukowiak, and E. Ito

The pond snail, Lymnaea stagnalis , can locomote on its back utilizing the surface tension of the water. We have called this form of movement ‘back-swimming’. In order to perform this behavior, the snail must flip itself over on its back so that its foot is visible from above. Little is known about the mechanism of this back-swimming. As a first step for the elucidation of this mechanism, we measured the speed of back-swimming of Lymnaea at the different times of the day. They back-swam significantly faster in the morning than just before dark. These data are consistent with our earlier findings on circadian-timed activity pattern in Lymnaea. Lymnaea appear to secrete a thin membrane-like substance from their foot that may allow them to back-swim. To confirm the existence of this substance and to examine whether this substance is hydrophobic or hydrophilic, we applied a detergent onto the foot during back-swimming. A single drop of 1% Tween 20 drifted Lymnaea away that were still kept at the water surface. These results suggest that Lymnaea secrete a hydrophobic substance from their foot that floats to the water surface allowing Lymnaea to back-swim.

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