1,3-Diacylglycerols were synthesized by direct esterification of glycerol with free fatty acids in a solvent-free system. Free fatty acids with relatively low melting points (<45°C) such as unsaturated and medium-chain saturated fatty acids were used. With stoichiometric ratios of the reactants and water removal by evaporation at 3 mm Hg vacuum applied at 1 h and thereafter, the maximal 1,3-diacylglycerol content in the reaction mixture was: 84.6% for 1,3-dicaprylin, 84.4% for 1,3-dicaprin, 74.3% for 1,3-dilinolein, 71.7% for 1,3-dieicosapentaenoin, 67.4% for 1,3-dilaurin, and 61.1% for 1,3-diolein. Some of the system's parameters (temperature, water removal, and molar ratio of the reactants) were optimized for the production of 1,3-dicaprylin, and the maximal yield reached 98%. The product was used for the chemical synthesis of 1,3-dicapryloyl-2-eicosapentaenoylglycerol. The yield after purification was 42%, and the purity of the triacylglycerol was 98% (both 1,3-dicapryloyl-2-eicosapentaenoylglycerol and 1,2-dicapryloyl-3-eicosapentaenoylglycerol included) by gas chromatographic analysis, of which 90% was the desired structured triacylglycerol (1,3-dicapryloyl-2-eicosapentaenoylglycerol) as determined by silver ion high-performance liquid chromatographic analysis.

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[1] We conducted deformation experiments of ice-1 mm silica beads mixture to clarify the effects of silica beads volume fraction and temperature on the strength. The silica beads volume fraction was changed from 0 to 0.63 to simulate the surfaces of icy bodies. Unconfined uniaxial compression tests were made in a cold room at the temperatures from À10°C to À25°C and the constant strain rates ranged from 2.9 Â 10 À3 to 8.5 Â 10 À7 s À1. We determined the rate dependent strength of the mixture written by _ e = A Á s max n from the relationship between the maximum stress, s max , on the stress-strain curve and the applied strain rate, _ e. At À10°C, the mixtures with silica volume fractions of 0.004 -0.04 had almost the same strength with pure ice and the stress exponent, n, is about 3. On the other hands, at the silica volume fractions more than 0.15, the mixture became harder as the beads were more included, and it had the same stress exponent, about 6. This high stress exponent might be caused by crack generation. Also, we found that the A for silica volume fractions more than 0.15 was written by an exponential equation related to the silica volume fraction, f, A = 6.86 Â 10 À8 exp(À6.35f). Furthermore, we found that the n of f = 0.15 was independent of the temperature, and the brittle-ductile boundary of f = 0.29 and 0.63 was more than 30°C higher than that of pure ice. Citation: Yasui, M., and M. Arakawa (2008), Experimental study on the rate dependent strength of ice-silica mixture with silica volume fractions up to 0.63, Geophys. Res. Lett., 35, L12206,