W.J. O'Sullivan

Thermal expansion of methanol + cyclohexane near the critical solution point☆

Abstract We report precise measurement of volume changes as function of temperature in the one phase region of methanol + cyclohexane near the critical solution point. We find a value for the critical exponent α of 0.11 ± 0.07 in the region 11 Mk 1 8 . For temperatures closer to Tc we observe a stronger divergence. In addition we observe unusual behavior over a small region of temperature centered at T – Tc = 15 mK.

The effect of double scattering on critical fluid Rayleigh linewidth measurements

Abstract We apply recent work on the intensity correlation function of light double scattered from a system of brownian diffusing balls to the case of a fluid near the critical point. We evaluate the relative intensities and intensity correlation times of the polarized and depolarized components of the double scattered light as a function of k 0 ξ. We compare these correlation times to those found for single scattering and find that the more intense polarized component of the double scattered light has a correlation time nearly equal to the singly scattered light in the critical region where k 0 ξ ⪆ 8 .

On lysozyme as a possible high-temperature superconductor

Intensity autocorrelation measurements of the diffusion constant of lysozyme molecules in aqueous solutions as a function of applied magnetic field reveal no evidence of the cooperative behaviour proposed by Ahmed, Calderwood, Frohlich and Smith (1975, 1976) to explain their observation of a large peak in the diamagnetic susceptibility of lysozyme at an applied field of 600 Oe. Careful susceptibility measurements using a SQUID system show that the diamagnetic susceptibility of lysozyme and lysozyme solutions is constant up to a maximum field of 720 Oe.

K‐dependent Brownian diffusion constant in a critical mixture

The K ‐dependent diffusion constant of 0.3μ Teflon particles in the critical mixture isooctane‐nitroethane has been measured for 0.001 < T − T c < 2 °C. The results are presented along with a simple theory that gives good agreement by considering the surface energy force on the particle due to concentration fluctuations.

Droplet model for sound absorption in fluids near the critical point

Abstract The dynamic droplet model of critical fluids is applied to understanding critical fluid sound absorption. The resonance frequency of an oscillating droplet is used to explain the scaling on frequency and temperature observed in sound absorption data.

Simulation of critical fluid Rayleigh linewidth behavior by a normal fluid system

Abstract The dynamic droplet model of a critical fluid provides a simple physical model of a critical fluid. We use this to model an emulsion which mimics the Rayleigh linewidth behavior of a critical fluid in the nonhydrodynamic regime.