The conductometric determination was made of the association constants of α-cyclodextrin (αCD) with ionic surfactants and their homologs. For 1-alkanesulfonate ions with carbon atoms (n) of 5–12, the association constant was found to increase regularly with n and become abruptly constant at n=10. The association constants for sodium 1-dodecanesulfonate, dodecylammonium chloride, dodecyltrimethylammonium chloride, and 1-dodecylpyridinium chloride were all similar in their magnitude. The effect of complexation on the micellar properties of sodium dodecyl sulfate and dodecyltrimethylammonium chloride were also studied potentiometrically by determining the counterion activities. In both cases, the critical micelle concentration increased regularly, while the degree of counterion association to the micelle decreased almost linearly with increasing αCD concentrations. It was suggested that the αCD-surfactant ion complex is solubilized in the hydrophilic surface region of surfactant micelle to give rise to a decrease in the surface charge density.

The association constants (K) of β-cyclodextrin with 13 amphiphilic ions were determined. For a homologous series 1-alkanesulfonate ions, the saturation phenomenon of K occurred at the number of carbon atoms of 10. The values of K for amphiphilic ions with dodecyl chain were similar to one another.

The binding isotherm of dodecyltrimethylammonium ion to partially hydrolyzed poly(potassium vinyl sulfate) was determined potentiometrically as a function of the average separation (d) between neighboring ionic groups. The cooperativity in binding process was found to decrease rapidly to about d≈0.44 nm and eventually disappear at d≈3.7 nm.

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We observed the SiO ($v=1$ and $v=2$, $J=$ 1-0) maser emissions toward the Mira variable IK Tauri (IK Tau, NML Tau, IRC$+$10050) over nine epochs from 2003 November to 2005 April using the VLBI Exploration of Radio Astrometry (VERA) telescope array. We found that the SiO maser distributions around IK Tau are highly variable, depending on the stellar pulsation phase. The velocity structures were complex and also time-variable, and are inconsistent with a simply rotating shell that was suggested by previous observations. Based on fittings of the SiO maser distributions to elliptical ring models, we found that the ring size seems to vary in correlation with the pulsation phase, as previously found for TX Cam. Comparisons of the $v=1$ and $v=2$ maser distributions reveal that 42-50% of the maser pairs have a positional offset less than 0.5mas, suggesting that the maser pumping in these spots is likely to be dominated by line overlapping or collisional pumping, rather than pure radiative pumping. In order to model the velocity structure of the spoke-like features observed in IK Tau, we propose a ballistic-orbit model, in which a gas clump ejected from the stellar surface moves radially outward with a gravitational deceleration, and argue that the stellar mass can be deduced from that model.