In the preceding paper, the enzymatic formation of the ascidian flavor derived from n-alcohols in viscera of Halocynthia roretzi was demonstrated. This paper deals with the isolation and identification of the precursors responsible for the flavor formation. The precursors have been isolated from the ethanol extracts of viscera by using solvent fractionation and chromatographic techniques. Each fraction was assayed for the activity of octanol generation in reaction with crude enzyme. The precursors have been identified as salts of alkyl sulfates with carbon atoms 8 to 10. The structures were confirmed by elementary analyses, composition of hydrolysis products, and direct comparison of IR spectra and Rf values on TLC with those of an authentic sample. The role of alkyl sulfates in the ascidian is also discussed.
Three types of geotomographic surveys (seismic tomography, resistivity tomography, and radar tomography) were conducted at a highway bridge pier construction site to investigate rock characteristics. After the geophysical investigation, bedrock was excavated to construct the bridge foundation. Geological surveys and plate-loading tests were carried out on the excavated surface. The geophysical and geological results were generally in good agreement.
Seismic tomography can distinguish highly fractured rock from unfractured rock, and resistivity tomography and radar tomography can classify rock according to different water contents. The combined use of these three geotomographic surveys made it possible to detect the anomalous zone which was highly fractured and saturated.
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