Several proteins, such as tobacco mosaic virus coat protein and the beta protein of the bacteriophage lambda, are known to exhibit unique dynamic self-organization processes involving ring-shaped and extended helical nanostructures triggered by chemical stimuli. However, transformation of rings into coils as observed in biological assemblies has never been realized with synthetic molecular building blocks. Oligo(p-phenylenevinylene) functionalized on one end with barbituric acid and on the other end with aliphatic tails self-organizes in aliphatic solvents to form nanorings through hydrogen-bonding and pi-stacking interactions. Upon an increase in concentration, the nanorings transform into rodlike nanostructures, which are considered to be formed through helically coiled objects consisting of quasi-one-dimensional fibers.

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A method for evaluating the mean effective gain (MEG) of mobile antennas in line-of-sight (LOS) street microcells with low base station antennas is investigated. The received power patterns of incident radio waves along typical streets measured in actual street microcells in urban areas of Tokyo are presented to clarify the proper distribution model for the incident radio waves. A two-dimensional statistical distribution model is proposed based on the measured received power patterns for the incident radio waves that follow a Gaussian distribution in the azimuth angle, but are concentrated in the horizontal plane in the elevation angle. The two-dimensional theoretical expression of the MEG that consists of the incident distribution model function and the radiation patterns in the horizontal plane of the mobile antennas is derived to evaluate easily the MEG. We show that the MEG values in street microcells are not defined as only one value and form the MEG pattern because the MEG values are changed by the relative direction of the radio waves arriving at the mobile station antennas. The measured and calculated MEG values (MEG patterns) of the whip antennas used in the experiments are in good agreement. The average error between the measured and calculated MEG values is within approximately 4.5 dB at maximum. The results show that the MEG degradation of the mobile station antennas due to the effect of the human body is properly evaluated by the proposed distribution model. The proposed statistical distribution model is valid and effective in both estimating the MEG values of mobile antennas and designing the LOS street microcell systems with low base station antennas.Index Terms-Line-of-sight (LOS) street microcells, low base station antennas, mean effective gain (MEG), mobile antennas, statistical distribution model of incoming radio waves.

Bis- and monoureas hybridized with the oligo(p-phenylene vinylene) (OPV) pi-electronic segment and 3,4,5-tridodecyloxyphenyl wedge were synthesized and their supramolecular polymerization in diluted solution, gel formation in concentrated solution, and liquid crystallinity in bulk state were investigated. Bisurea 1a featuring a hexamethylene linker showed the highest supramolecular polymerization ability and formed tapelike nanofibers that can gelate various organic solvents. On the other hand, bisurea 1b featuring a dodecamethylene linker and monourea 2 showed a lower degree of supramolecular polymerization, resulting in gel formations in a smaller variety of solvents. These results clearly reflect a high level of cooperativity between the two urea sites and the two OPV segments of 1a upon hydrogen-bonding and pi-pi stacking interactions, respectively. When the gels of 1a, 1b, and 2 were dried, all the compounds self-organized into multilamellar superstructures. Thermal treatment of these lamellae at high temperatures induces columnar liquid-crystalline mesophases as a result of microsegregation between the rigid OPV parts and the molten aliphatic wedges. These results demonstrate that the present molecular constituent is very useful for fabricating dye-based functional assemblies providing nanoscale pi-electronic fibers, and solvent-incorporated and bulk soft materials.