No abstract

The purpose of these experiments was to determine the potential estrogenic, androgenic, and progestagenic activity of two cyclic siloxanes, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5). Receptor-binding experiments and a luciferase reporter gene assay were used to determine if the materials were able to bind and activate either the estrogen receptors (ERs) or progesterone receptors (PRs)-alpha or beta. The rat uterotrophic assay (RUA) for estrogenic activity and the Hershberger assay for androgenic activity were utilized as the in vivo assays. For the ER-binding studies, D4 was shown to bind to ERalpha but not to ERbeta. D5 did not bind to either of the two receptors. D4 activated the reporter gene at 10 microM, while D5 was considered negative in the estrogen reporter gene assay. Neither material was a ligand for the PRs. Both the RUA and Hershberger assays were conducted using whole-body inhalation of the two materials for 16 h/day. D4 resulted in a small but significant increase in both wet and blotted uterine weight as well as increases in both luminal and glandular epithelial cell height in both Sprague Dawley and Fischer 344 rats. D5 was negative in both rat strains, indicating that D5 does not possess estrogenic activity. Neither material possessed any significant antiestrogenic activity. Both materials were negative in the Hershberger assay indicating that neither material possesses any significant androgenic activity. Our studies have shown that D4 exhibits a low affinity for ERalpha in vitro and a weakly estrogenic response in vivo.

Carbon nanocages, with remarkably large mesoporous volumes, have been synthesized by the deposition of p-xylene over a Co/Mo catalyst in supercritical carbon dioxide. Nanocages with diameters ranging between 10 and 60 nm were synthesized at temperatures between 650 and 750 °C. The surface area and pore volume of the nanocages produced was found to depend on the reaction temperature and pressure employed. In particular, carbon nanocages with a pore volume of up to 5.8 cm 3 g -1 and a BET surface area of 1240 m 2 g -1 were readily synthesized at a temperature of 650 °C and a pressure of 10.34 MPa. The high pore volume and surface area of the carbon nanocages synthesized makes them ideal materials for use as inert adsorbents and catalytic supports.