Direct numerical simulations with a spectral method are performed to study the effects of spanwise rotation on a turbulent Poiseuille flow at very low Reynolds number. At this Reynolds number, the region of zero absolute vorticity, typically observed in the mean velocity profile of rotating Poiseuille flow, disappears in the channel center, and the mean velocity gradient becomes opposite to that of zero absolute vorticity. When zero absolute vorticity disappears, very long low-speed streaks, accompanied by the vortices aligned in the streamwise direction like a chain, dominate the flow, in which the transfer of turbulent kinetic energy into the vicinity of the wall and small-scale streamwise vortices disappear there. However, low-speed fluids are pumped up from the near-wall region, and trapped into the channel center by the larger-scale chain vortices away from the wall, which decreases the mean velocity in the channel center and shifts its peak location toward the wall.

The fluorescence behaviors of potential-sensitive dyes including anionic DiBAC4(3) (denoted by dye A), DiSBAC2(3) (dye B), and zwitterionic di-4-ANEPPS (dye C) were studied in oil-in-water (O/W) emulsions. In this study, the equilibrium Galvani potential difference (Δ O W eq) of the O/W-emulsion droplets was controlled by changing the ratio of the concentrations of electrolytes added to the O (=1,2-dichloroethane) and W phases. When using an adequate combination of the dyes, i.e., B and C, we could observe that the ratio of their fluorescence peak intensities was changed from 1.08 to 1.38, depending on the change of (Δ O W eq from 26 to 73 mV. It is desirable to apply this method to study the potentialdependent ion or electron-transfer reactions occurring at vesicles or liposomes, and also to biomembranes.

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Preparation and characterization of a WO3-based thin film gas sensor are reported. The WO3 film was prepared on a polished alumina substrate by a sol-gel method using an aqueous mixture solution of ammonium metatungstate hydrate and poly-vinyl alcohol, and fabricated into the gas sensor by forming interdigital electrodes on the surface. The characterization was conducted by measuring the electrical resistance change in NO, H2, and NH3 ambient as a function of gas concentration. It is revealed that the sensor has a specific sensitivity to NO, NO is detected as oxidizing gas although it is expected to be reducing gas, and the resistance changes with gas concentration in accordance with the Langmuir isotherm plot.

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