Some difficulties have arisen on appropriate design of the graphite dies, on applying the DC pulse resistance pressure sintering process, which is more efficient process than other conventional sintering processes such as hot pressing process, to a complex shaped part of non-conductive ceramics powder such as zirconia powder. In the present paper, the non-steady electro-thermomechanical finite element analysis of the sintering process of the zirconia cylindrical can was performed. As a result, it was found that the enough heating of the graphite dies that contacts with zirconia powder, and heat transmission from the die to zirconia powder was essential for the success of the sintering with adequate density. Moreover, the lower density region was found at the inside of the can during the process, which corresponded to the region where the convex shape formed in experiments. Furthermore, the high tensile residual circumferential stress was observed at the side wall from the simulation of the cooling process, which is caused by the different thermal expansion ratio of the graphite and zirconia materials. This stress was considered to be related with the fracture of the can longitudinally during cooling process in experiments.

Citreoviridin (CTV) is a mycotoxin that is produced by Aspergillus terreus, Eupenicillium ochrosalmoneum and Penicillium citreonigrum, and CTV has been detected in a wide range of cereal grains throughout the world. Furthermore, it is especially a serious problem in regions where rice is consumed as a staple food. Moreover, CTV is a well-known yellow rice toxin, and outbreaks of beriberi have occurred due to consumption of rice that is contaminated by CTV even in the recent years. Although CTV biosynthetic genes of A. terreus have been described, those of P. citreonigrum remain unclear, which is concerning since P. citreonigrum is the main cause of CTV contamination in rice. In the present study, we determined the draft genome of the P. citreonigrum strain IMI92228 and revealed the presence of all four genes that form a gene cluster and that are homologous to the CTV biosynthesis genes of A. terreus. The expression of these four homologous genes were highly correlated with CTV production, suggesting that they may play an important role in CTV biosynthesis in P. citreonigrum. We concluded that the gene cluster is a CTV biosynthesis cluster of P. citreonigrum. The findings will contribute to the understanding of the biosynthetic pathway of CTV and will ultimately lead to improvements in the CTV management of agricultural products.

Hydrophilic copolymers containing N-isopropylacrylamide and acrylate with coumarin or 4-methylcoumarin moieties have been synthesized. We reveal that the copolymers with a very small content of coumarin and 4-methylcoumarin units exhibit macroscopic photoinduced and reversible sol-gel conversions. UV light (λ>310 nm) irradiation of aqueous solutions for the copolymers causes the increase in viscosity and the formation of hydrogels, based on photodimerization of coumarin moieties. Subsequent irradiation with UV light (λ=254 nm) of the hydrogels induces the return of fluidity and the change to sol state, due to the decomposition of coumarin dimers. The amount of crosslink structures in the copolymers can be regulated by the reversible photoreaction of coumarin moieties.

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