We demonstrate the fabrication of chitin nanofibril aerogels and their successful application as base catalysts for the production of useful chemicals. Squid-pen chitin nanofibrils (ChNF) with primary C2-amine groups on their crystalline surfaces were fabricated into highly porous aerogels with high specific surface areas up to 289 m(2) g(-1) using freeze-drying or a supercritical drying process. The prepared ChNF aerogel was used in the aqueous Knoevenagel-condensation reaction and acted as a highly efficient base catalyst, suggesting that the combination of the nanofibrous aerogel structure and primary C2-amines exposed on the crystalline ChNF surface was effective for continuous flow catalysis. Because the ChNF aerogel can be easily prepared from abundant and renewable chitin present in nature, this strategy is a gateway to promoting and conducting green and sustainable chemistry.

Aqueous dispersions of partially deacetylated a-chitin (PDACh) were prepared using various organic and inorganic acids in water under various pH and ionic strength conditions. The degree of PDACh nanofibrillation in the dispersions was investigated by measuring their light transmittances, nanofibrillation yields, and zeta-potentials, and by atomic force microscopy observations. Highly transparent dispersions, consisting of mostly individualized PDACh nanofibrils (w = 3.4 ¡ 1.5 nm), were obtained when ascorbic acid and certain monovalent acids were used in water at pH 3.5. However, unfibrillated PDACh bundles were present in dispersions prepared with divalent and trivalent acids, probably because of formation of ionic cross-linkages between PDACh fibrils. When the acid concentration in the dispersions was adjusted to 0.04 M, those with higher dispersion pH exhibited higher nanofibrillation efficiency.Addition of excess acid inhibited efficient nanofibrillation of PDACh, owing to the high ionic strength that concomitantly occurred.

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A procedure based on the Janbu method for slope stability analysis and Newmark's sliding block method for displacement calculation is proposed to evaluate rationally the earthquake-induced displacement of slopes containing a weak layer. In the procedure, the eŠects of the irregular geometry of the sliding plane and generation of excess pore water pressure in the weak layer which forms partly the sliding plane are considered. In the computation following the proposed procedure, a negative yield seismic coe‹cient to induce a safety factor of unity can be obtained because of the eŠect of excess pore water pressure, while the residual displacement can become aˆnite value because the sliding plane becomes ‰atter in general after the slope undergoes a large displacement.

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