Pressure-induced conformation transition of o-phenylene solvated in bulk hydrocarbons.

The conformational behavior of o-phenylene 8-mers and 10-mers solvated in a series of linear alkane solvents by means of classical molecular dynamics and first-principles calculations was studied. Irrespective of the solvent used, we find that at ambient pressure the molecule sits in the well-defined close-helical arrangement previously observed in light polar solvents. However, for pressures greater than 50 atm, and for tetradecane or larger solvent molecules, our simulations predict that o-phenylene undergoes a conformational transition to an uncoiled, extended geometry with a 35% longer head-to-tail distance and a much larger overlap between its lateral aromatic ring groups.

Ten Ways to Provide a High-Quality Acoustical Environment in Schools.

The purpose of this article is to describe the use of impulse response measures and observations in Florida classrooms. As a result of measures and observations in "healthy" and poor acoustical environments, 10 practical recommendations are proposed for improving the acoustical environment in schools. The primary research for these recommendations consisted of recording acoustical measurements of reverberation time and background noise, as well as newer acoustical measurements based on impulse response techniques, in 56 actual classrooms.