Mechanoresponsive Fluorescence On-off Switching of Two-component Emitters Composed of Mechanochromically Luminescent Dyes and Non-emissive Pigments.

Organic emitters capable of changing their luminescence properties in response to mechanical stimuli have recently attracted considerable attention. While mechanoresponsive switching of luminescence color has been widely investigated, there are only a limited examples regarding the on-off luminescence intensity switching by mechanical stimulation. Consequently, rational design guidelines for mechanoresponsive switching of luminescence intensity have not been established. Herein, on-off luminescence switching has been achieved by two-component organic emitters composed of phenanthroimidazolylbenzothiadiazoles, which exhibit mechanochromic luminescence (MCL), and non-emissive pigments. In these two-component emitters, the emission color can be tuned by changing the MCL dye, and the apparent color under room light can be modulated by changing the non-emissive pigment. Moreover, we have demonstrated the encryption and decryption of luminescent displays by using the two-component emitter. The present two-component strategy is expected to serve as a useful method for developing advanced mechanoresponsive luminescent materials.

In Situ Exploration of Stimulus-Induced Emission Changes in Mechanochromic Dyes.

The development of in situ analysis techniques for visualizing and linking macro- and nanoscopic features of external stimulus-responsive materials is crucial for their rational design and applications. Herein, we investigate the mechanical stress-induced emission changes in electron donor-acceptor type organic dye molecules in solid states through in situ single-particle fluorescence spectroscopy combined with macroscopic and nanoscopic stimulation systems. The change in emission color from green to yellow was attributed to repeated rubbing or scratching of the crystal surface, and not to simple cutting. This change was due to partial amorphization, which changed the intra- and intermolecular charge-transfer interactions of stacked molecules near the surface. We believe that this study will facilitate the efficient design of mechano-responsive materials with finely controlled and responsive properties.

The bovine lactophorin C-terminal fragment and PAS6/7 were both potent in the inhibition of human rotavirus replication in cultured epithelial cells and the prevention of experimental gastroenteritis.

Rotaviruses are the leading cause of severe dehydrating diarrhea in children worldwide. We have found that high-M(r) glycoprotein fraction (F1) from cow's milk whey has potent inhibitory activity against human rotavirus (HRV) in cell culture. The present study was undertaken to identify and characterize the components responsible for this inhibitory activity. F1 was initially heated at 95 degrees C for 30 min, rendering milk antibodies inert, subjected to ammonium sulfate fractionation, and then resolved by two-dimensional polyacrylamide gel electrophoresis. After electroelution, we found that a heat-stable milk protein lactophorin C-terminal fragment (LP16) and bovine milk fat globule membrane protein PAS6/7 strongly inhibited the replication of HRV MO strains in MA104 cells. Furthermore, we found that prophylactic oral administration of F1 once before inoculation of the HRV MO strain obviously prevented the development of diarrhea in vivo. These non-immunoglobulin components are a promising candidate for a prophylactic food additive against HRV infection.

Volatile components of the straw of Oryza sativa L.

The components of the volatile oils from the straws of Oryza sativa L. (Onshinomai, Asamurasaki, Hinohikari) were analyzed by capillary GC/GC-MS. The quantification of volatile compounds in the oils was made by the internal standard method, using palmitic acid as reference substance. Palmitic acid was the most abundant component in these samples, followed by hexahydrofarnesyl acetone and phytol.