Comets: chemistry and chemical evolution.

Lasting commitment to cosmic chemistry and an awareness of the fascinating role of comets in that study was a consequence of an association with Harold Urey early in my astronomical career. Urey's influence on cometary research spread as colleagues with whom I was associated, in turn, developed their own programs in cometary chemistry. One phase of the Chicago research shows that Whipple's icy nucleus would be below about 250 K.

Condensation of nonequilibrium phases of refractory silicates from the vapor.

Silicon monoxide solid was evaporated in a bell jar containing reducing, neutral, or oxidizing atmospheres at pressures of a few torr. The vapor invariably condensed as smoke-sized particles of silicon sesquioxide, Si(2)O(3). The condensation of a solid whose composition differs from that of the parent gas and is apparently the least stable of the three solid species illustrates the importance of specific nucleation effects in the condensation process.

The free connective tissue autograft: a clinical and histologic wound healing study in humans.

In this report a new method for the management of the soft tissue autograft, based on the concept that some form of control lies in the connective tissue of the periodontium which determines the type and character of the overlying epithelial tissues is presented, along with an insight into the wound healing process.