Organic-inorganic hybrid gels have been synthesized from siloxane, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), tetrakis(dimethylsilyloxy)silane (TDSS) or silsesquioxane, 1,3,5,7,9,11,13,15-octakis(dimethylsilyloxy)-pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as crosslinking reagents and a,o-nonconjugated dienes, 1,5-hexadiene (HD), 1,7-octadiene (OD) and 1,9-decadiene (DD), using a hydrosilylation reaction with a Pt catalyst. The network structures of the resulting gels were investigated by means of a novel scanning microscopic light scattering system. The structures of the crosslinking reagent and the length of the a,o-non-conjugated dienes strongly affected the formation and network structures of the resulting gels. The critical gel concentration decreased when the molecular length of the non-conjugated diene used was increased. The structures and Si-H group numbers of the crosslinking reagents affected the critical gel concentration, and its values decreased in the following order: TDSS > TMCTS > POSS. The mesh size distribution in the network structure was quantitatively characterized using the light scattering system and almost presupposed sizes with quite narrow size distributions were attained in the gels from TMCTS-HD, OD systems and TDSS-OD systems. On the other hand, the gels derived from POSS or DD showed larger mesh sizes than expected.

Organic-inorganic hybrid gels have been synthesized by means of co-gelation of multi-functional cyclic siloxane, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), or cubic silsesquioxane, 1,3,5,7,9, 11,13,15-octakis(dimethylsilyloxy)pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as crosslinking reagents with a,v-non-conjugated dienes, a hexa-1,5-diene (HD) and deca-1,9-diene (DD) mixture, using hydrosilylation reaction with Pt catalyst. Network structures of the resulting co-gels have been quantitatively characterized by means of a novel scanning microscopic light scattering system. The feed ratio of HD to DD strongly affects the gelation and mesh size of the co-gels. Whereas the mesh size of the POSS-HD/DD co-gel increased with an increase of DD in the feed ratio. The mesh-size distribution of the co-gels was narrower than the gels synthesized from single a,v-non-conjugated dienes. Co-gelation of a TMCT/POSS-DD system was also investigated, and the critical gelation concentration showed maximum values for the co-gelation with a feed ratio of [TMCTS]/[POSS] ¼ 1. The mesh size of the co-gel increased with increasing POSS ratio in the feed.

Doubly labeled water (DLW) can be used to measure energy expenditure in free-ranging animals, but questions have been raised about its accuracy in different species or contexts. We investigated whether differences in the extent of isotope elimination affects the precision and accuracy of the DLW method, which can vary according to the experimental design or metabolic rate of the species. Estimated total energy expenditure by the DLW method (TEEdlw) was compared with actual total energy expenditure simultaneously measured via respirometry (TEEresp) in streaked shearwaters Calonectris leucomelas, a pelagic seabird. Subjects were divided into three groups with different experimental conditions: at rest on the ground for 24 h (Group A) or for 48 h (Group B), and at rest on the water for 24 h (Group C). TEEdlw in Group A matched TEEresp, whereas there was an overestimation of TEEdlw in both Groups B and C compared with TEEresp. However, compared with Group A, TEEdlw in Groups B and C had reduced the isotopic analytical variability and thus higher precision. The best regression model (TEEdlw = 1.37 TEEresp − 14.12) showed a high correlation (R2 = 0.82) between TEEdlw and TEEresp and allows a correction factor for field metabolic rates in streaked shearwaters. Our results demonstrate that the commonly made assumption that the DLW method is not appropriate for individual-based estimates may be incorrect in certain circumstances. Although a correction factor may be necessary when using the DLW method to estimate metabolic rate, greater levels of isotope eliminations provides DLW estimates with high precision, which can adequately represent relative individual estimates. Nevertheless, the DLW method, should be used with caution when characterizing interspecies difference of energy expenditures.

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