Role of Displacing Confined Solvent in the Conformational Equilibrium of ß-Cyclodextrin.

This study investigates the role of hydration and its relationship to the conformational equilibrium of the host molecule ß-cyclodextrin. Molecular dynamics simulations indicate that the unbound ß-cyclodextrin exhibits two state behavior in explicit solvent due to the opening and closing of its cavity. In implicit solvent, these transitions are not observed, and there is one dominant conformation of ß-cyclodextrin with an open cavity. Based on these observations, we investigate the hypothesis that the expulsion of thermodynamically unfavorable water molecules into the bulk plays an important role in controlling the accessibility of the closed macrostate at room temperature. We compare the results of the molecular mechanics analytical generalized Born plus nonpolar solvation approach to those obtained through grid inhomogeneous solvation theory analysis with explicit solvation to elucidate the thermodynamic forces at play. The work illustrates the use of continuum solvent models to tease out solvation effects related to the inhomogeneity and the molecular nature of water and demonstrates the key role of the thermodynamics of enclosed hydration in driving the conformational equilibrium of molecules in solution.

Who uses safe ride programs: an examination of the dynamics of individuals who use a safe ride program instead of driving home while drunk.

Drinking and driving are still a serious concern on the roads, even though the last twenty years has seen an increase in exposure to various designated driver programs. Even though a majority of people have either been one or used one, most designated drivers have still consumed some alcohol. Another option is that of an outside driver, such as a safe ride program in which a safe ride is offered for free by taxis or volunteers. One such program under study, offers a ride home for both the driver as well as their vehicle. To examine the population who utilizes such a program two studies were conducted which included 1,985 participants (1206 male, 744 female) from two major California cities. The volunteer drivers gathered data during their rounds between January 2002 and September 2002. If the current safe ride program not been in place 632 Participants (44%) reported that they would have driven themselves home. 582 participants (40%) have used back roads in the past to evade being stopped by the police; on average they used back roads 3.4 times in the past month. When questioned about having control over not drinking and driving 455 (32%) participants didn't feel they had control over their choice to avoid drinking and driving. Participants who reported having driven back roads in the past to avoid confrontation with the police after drinking had significantly higher estimated BAC levels than those who said they had never done so. This sample reflected similar populations.

Acceptance of and engagement in risky driving behaviors by teenagers.

Data gathered from 1,430 teenage student drivers and 880 teenage traffic violators were used to examine the levels of exposure to risky driving behaviors and perceptions concerning the level of danger of such behaviors. For student drivers, 55% reported exposure to risky driving by being in a car with a driver engaging in such activities as drunk driving, drag racing, and reckless driving. For the traffic violators, 43% had been engaged in one or more of the risky driving behaviors. Teenagers who had been exposed to risky driving practices were more accepting of risky driving behaviors.