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Porous thin films containing very small closed pores (∼ 20 A) with a low dielectric constant (∼ 2.0) and excellent mechanical properties have been prepared using the mixture of cyclic silsesquioxane (CSSQ) and a new porogen, heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (tCD). The pore sizes vary from 16.3 A to 22.2 A when the content of tCD in the coating mixture increases to 45 wt.-% according to positronium annihilation lifetime spectroscopy (PALS) analysis. It has also been found that the pore percolation threshold (the onset of pore interconnectivity) occurs as the ∼ 50 % tCD porogen load. The dielectric constants (k = 2.4 ∼ 1.9) and refractive indices of these porous thin films decreased systematically as the amount of porogen loading increased in the coating mixture. The electrical properties and mechanical properties of such porous thin films were fairly good as interlayer dielectrics.

A new model has been developed to account for the dependence of the optical anisotropy of a dye polarizer on the dye concentration. The effect of the dye concentration has been studied through an examination of the changes in the orientation distribution of the polymer. The model takes into account the intrinsic optical anisotropy of the dichroic dye, the polymer orientation, the polymer orientation distribution, and the dye orientation with respect to the polymer. It is assumed that (1) the orientation distribution function of the polymer segments can be expressed as an elliptical distribution function and that (2) the free rotation of each dye molecule on its axis is suppressed because of the attraction force between the dye molecules and the polymer chains. The pseudo-order parameter, which takes into account the aforementioned assumptions, determines the relation between single-piece transmittance and polarizing efficiency. The orientation distribution of the polymer molecules in the experiment and its effect on the optical performance of a polarizer are quantitatively determined. The model predicts that the effect of the orientation distribution becomes more significant as the polymer chains are oriented more highly. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1363–1370, 2002

A study group of 240 impotent men receiving intracorporeal injections were divided into 2 groups: the first group received papaverine (60 mg) and the second prostaglandin E1 (PGE1 20 micrograms). The effect of the drugs was evaluated according to the onset of erection, rigidity and the duration of erection; 136 patients were treated with papaverine and 104 with PGE1. The onset of action in these groups was 6.42 +/- 5.39 vs 10.14 +/- 5.41 min; the rigidity score was 3.37 +/- 0.89 vs 3.60 +/- 1.10 and the duration of erection was 49.56 +/- 62.56 vs 63.60 +/- 44.57 min respectively. There was a significant difference in the onset of action (PGE1 was slower than papaverine) and maintenance of erection (longer with PGE1 than with papaverine). Another group of 17 patients received both papaverine and PGE1. The effects of papaverine were better in 4 cases, worse in 5 and equal to PGE1 in 8. This study indicates that compared with papaverine, treatment with PGE1 produces a slower onset of action, a longer duration of erection and fewer side effects.