Modeling the pH dependent hydrolysis of VX for aqueous releases

The fate of chemical warfare agents (CWAs) in aqueous environments is not well characterized. Limited physical and kinetic data are available in the open literature for this class of chemicals, in part due to the dangers associated with exposure to these compounds. As a result, the development of methods for determining the persistence and extent of impact of a waterborne chemical agent release remains largely unanswered. In this study a basic hydrolysis model was developed to track the fate of VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate) from an instantaneous point source aqueous release. Hydrolysis product generation tracking was developed to determine the instantaneous pH within the local dispersive environment. Using instantaneous local pH values, the impact of pH on the persistence of VX hydrolysis rate was investigated for three different aqueous environments with varying dispersive conditions. Modeling results indicate that an accurate characterization of the pH dependence of the hydrolysis rate constant becomes more important in lower pH and lower turbulence environments. With this basic model, estimates of the time and extent of lethality of a VX release can be made.     

Anxiety management training and relaxation as self-control in the treatment of generalized anxiety in medical outpatients.

55 23–72 yr old outpatients expressing interest in a 6-wk program on coping with stress and anxiety were assigned to 1 of 3 groups: relaxation as self-control (RSC), anxiety management training (AMT), or waiting-list control groups. Pre- and posttreatment assessments included the State–Trait Anxiety Inventory and the Multiple Affect Adjective Check List. At posttreatment and 4-wk follow-up assessments, AMT and RSC groups reported significantly less trait and state anxiety and stress reactivity in 2 stressful situations, general physiological arousal, person-specific anxiety symptoms, depression, and anger than the control group. Among these measures only 1 difference was found between AMT and RSC, and it was not significant at follow-up. No between-groups differences were found on systolic or diastolic blood pressure. No differences were found on resting heart rate posttreatment. At follow-up, however, the RSC group had a significantly lower heart rate than the control group. Results are interpreted in terms of both the efficient development of relaxation coping skills for medical outpatients and the potential for counseling psychology in behavioral medicine. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)