Evaluation of Dynamic Models of Distillation Columns with Emphasis on the Initial Response

The flow dynamics (tray hydraulics) are of key importance for the initial dynamic response of distillation columns. The most important parameters are the liquid holdup, the liquid hydraulic time constant and the vapor constant representing the initial effect of a change in vapor flow on liquid flow. In the paper we present methods for determining these parameters experimentally, and compare the results with estimates from available correlations such as the Francis Weir formula

Contingent reinforcement for benzodiazepine-free urines: evaluation of a drug abuse treatment intervention.

This study evaluated contingent reinforcement for benzodiazepine-free urines as a therapeutic intervention for promoting reduced use of supplemental benzodiazepine drugs among methadone maintenance outpatients. Ten methadone maintenance patients were selected for participation on the basis of positive urinalysis results. During a 12-week intervention period these patients were offered clinic privileges, including monetary payments or methadone take-home doses, contingent on benzodiazepine negative urinalysis test results. Eight of ten participants responded to the intervention with at least 2.5 weeks of consecutive clean urines. An increase in benzodiazepine-negative tests during the contingent reinforcement period was significant for the group as a whole. The results suggest that more widespread application of contingent reinforcement procedures may be warranted in drug abuse treatment clinics

Contingency management interventions: effects on treatment outcome during methadone detoxification.

We examined the effectiveness of a contingency management program in preventing relapse to illicit opiate use and increasing treatment retention during outpatient methadone detoxification treatment. Twenty male opiate addicts were randomly assigned to an experimental or control group. Following a 3-week methadone stabilization period, men in both groups received identical gradual methadone dose reductions during Weeks 4 through 9 and were maintained on placebo during Weeks 10 through 13. Beginning in Week 4, control patients received $5.00 for providing a specimen twice weekly. Experimental patients received$10.00 and a take home methadone dose for each opiate-free urine specimen but forfeited the incentives and participated in more intensive clinic procedures when specimens were opiate positive. The contingency management procedure slowed the rate of relapse to illicit opiate use. Experimental patients provided significantly more opiate-free urines during the methadone dose reduction in Weeks 4 through 9 than control patients, although the difference between groups was no longer significant during placebo administration in Weeks 10 through 13. In addition, the contingency management program improved treatment retention and reduced symptom complaints during the detoxification. The usefulness and limitations of contingency management procedures for outpatient methadone detoxification are discussed