1,2-Bis(2-methyl-6-nitro-1-benzothiophen-3-yl)perfluorocyclopentene was found to undergo a reversible photochromic reaction in the single-crystalline phase. Upon irradiation with 366-nm light, the single crystal turned green with keeping the crystal shape. The colored crystal showed dichroism. When the crystal was rotated under polarized light, the color changed from yellow to blue. The yellow and blue colors were attributed to two perpendicular electronic transitions at 465 and 600 nm of the closed-ring form. The two transition moments coincide with the directions of short and long axes of the closed-ring form isomers, which were regularly packed in the crystal lattice.

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In April and May 2011, there was a serious food-poisoning outbreak in Japan caused by enterohemorrhagic Escherichia coli (EHEC) strains O111:H8 and O157:H7 from raw beef dishes at branches of a barbecue restaurant. This outbreak involved 181 infected patients, including 34 hemolytic-uremic syndrome (HUS) cases (19%). Among the 34 HUS patients, 21 developed acute encephalopathy (AE) and 5 died. Patient stool specimens yielded E. coli O111 and O157 strains. We also detected both EHEC O111 stx 2 and stx-negative E. coli O111 strains in a stock of meat block from the restaurant. Pulsed-field gel electrophoresis (PFGE) and multilocus variable-number tandem-repeat analysis (MLVA) showed that the stx-negative E. coli O111 isolates were closely related to EHEC O111 stx 2 isolates. Although the EHEC O157 strains had diverse stx gene profiles (stx 1 , stx 2 , and stx 1 stx 2 ), the PFGE and MLVA analyses indicated that these isolates originated from a single clone. Deletion of the Stx2-converting prophage from the EHEC O111 stx 2 isolates was frequently observed during in vitro growth, suggesting that strain conversion from an EHEC O111 stx 2 to an stx-negative strain may have occurred during infection.

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