The evaporation of a small droplet of a volatile fluid from a solid surface differs according to whether the fluid wets the surface. When the initial contact angle is less than 90°, the evaporation initially proceeds with an accompanying decrease in the contact angle but no change in the contact radius. This stage of evaporation dominates the time scale and has previously been described by a diffusion model. However, when the initial contact angle is greater than 90°, it is the contact radius that decreases rather than the contact angle. In this work we report detailed measurements of the evaporation of drops of water from Teflon film. On deposition the contact angles rapidly relax from around 112° to 108°, which is the equilibrium value for droplets in a saturated vapor. The angle then remains constant for the majority of the evaporation time. Eventually the system changes to a mode of evaporation in which both contact angle and radius change simultaneously. The data are compared to an extension of the diffusion model, and this provides estimates of the diffusion coefficient. It is suggested that the constant contact angle observed during much of the evaporation is a result of a local saturation of the vapor in the region of the contact line.

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Baryon masses are calculated in chiral perturbation theory at the one-loop-O(p 3 ) level in the chiral expansion and to leading order in the heavy baryon expansion. Ultraviolet divergences occur requiring the introduction of counter-terms. Despite this neccessity, no knowledge of the counter terms is required to determine the violations to the Gell-Mann Okubo mass relation for the baryon octet or to the decuplet equal mass-spacing rule, as all divergences cancel exactly at this order. For the same reason all reference to an arbitrary scale µ is absent. Neither of these features continue to higher-powers in the chiral expansion. We also discuss critically the absolute neccessity of simultaneously going beyond the leading order heavy baryon expansion, if one goes beyond the one-loop-O(p 3 ) level. We point out that these corrections in 1/MB generate new divergences ∝ m 4 /M10. These divergences together with the divergences occuring in one-loop-O(p 4 ) graphs of chiral perturbation theory are taken care of by the same set of counter-terms. Because of these unknown counter-terms one cannot predict the baryon mass splittings at the one-loop-O(p 4 ) level. We point out another serious problem of going to the one-loop-O(p 4 ) level. When the decuplet is off its mass-shell there are additional πN ∆ and π∆∆ interaction terms. These interactions contribute not only to the divergent terms ∝ (m 4 /M10), but also to nonanalytic terms such as ∝ (m 4 /M10)ln(m/M10). Thus without a knowledge of the coupling constants appearing in these interactions one cannot carry out a consistent one-loop-O(p 4 ) level calculation.

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The leading-order correlation corrections to the independent particle shell model momentum density distribution for ' 0 are calculated using the' Brueckner theory of finite nuclei. The Pauli corrected defect functions are calculated using Reid soft core B and de Tourreil-Sprung interaction potentials with harmonic oscillator starting wave functions and experimental shell model starting energies. The short-range correlations are found to modify significantly the independent particle shell model momentum density distribution for low momenta and to dominate it for' high momenta. Comments are made concerning the selection of ground state nuclear wave functions for calculating quasielastic scattering processes. NUCLEAR STRUCTURE '60, calculated momentum density distribution. Brueckner method finite nuclei; Reid soft core, Sprang potentials used.