Enhancing Thermomechanical Strength and Thermal Stability of Poly(dicyclopentadiene) Composites through Cost-Effective Fly Ash Reinforcement for Structural and Impact Applications.

Poly(dicyclopentadiene) (poly-DCPD) is a thermoset with potential for high-performance applications. In this research, epoxy resin was blended with different concentrations of fly ash class F particles at 0.0, 1.0, 10.0, and 50.0 wt.%, aiming to improve its use as a high-volume structural material by decreasing costs and reducing its negative environmental impact through using fly ash particles. A planetary Thinky mixer was used to initially mix the resin with the curing agent, followed by incorporating a Grubbs catalyst. The microstructures were analyzed using scanning electron microscopy (SEM), where particles were found to be homogeneously distributed over the polymer matrix. The thermomechanical behavior was evaluated via curing, compression, dynamic mechanical analysis (DMA), and thermo-gravimetric analysis (TGA). Nanoindentation tests were also conducted. Fly ash was found to decelerate the curing of the resin through the release of calcium ions that enhanced the exothermic reaction.

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs). A Study on Creep Response and Dynamic Loading.

Force Sensing Resistors (FSRs) are manufactured by sandwiching a Conductive Polymer Composite (CPC) between metal electrodes. The piezoresistive property of FSRs has been exploited to perform stress and strain measurements, but the rheological property of polymers has undermined the repeatability of measurements causing creep in the electrical resistance of FSRs. With the aim of understanding the creep phenomenon, the drift response of thirty two specimens of FSRs was studied using a statistical approach. Similarly, a theoretical model for the creep response was developed by combining the Burger's rheological model with the equations for the quantum tunneling conduction through thin insulating films. The proposed model and the experimental observations showed that the sourcing voltage has a strong influence on the creep response; this observation-and the corresponding model-is an important contribution that has not been previously accounted. The phenomenon of sensitivity degradation was also studied. It was found that sensitivity degradation is a voltage-related phenomenon that can be avoided by choosing an appropriate sourcing voltage in the driving circuit. The models and experimental observations from this study are key aspects to enhance the repeatability of measurements and the accuracy of FSRs.

Flammability limits of hydrated and anhydrous ethanol at reduced pressures in aeronautical applications.

There is interest in finding the flammability limits of ethanol at reduced pressures for the future use of this biofuel in aeronautical applications taking into account typical commercial aviation altitude (<40,000 ft). The lower and upper flammability limits (LFL and UFL, respectively) for hydrated ethanol and anhydrous ethanol (92.6% and 99.5% p/p, respectively) were determined for a pressure of 101.3 kPa at temperatures between 0 and 200°C. A heating chamber with a spherical 20-l vessel was used. First, LFL and the UFL were determined as functions of temperature and atmospheric pressure to compare results with data published in the scientific literature. Second, after checking the veracity of the data obtained for standard atmospheric pressure, the work proceeded with reduced pressures in the same temperature range. 295 experiments were carried out in total; the first 80 were to calibrate the heating chamber and compare the results with those given in the published scientific literature. 215 experiments were performed both at atmospheric and reduced pressures. The results had a correlation with the values obtained for the LFL, but values for the UFL had some differences. With respect to the water content in ethanol, it was shown that the water vapor contained in the fuel can act as an inert substance, narrowing flammability.

Drug-loaded nanocarriers: passive targeting and crossing of biological barriers.

Poor bioavailability and poor pharmacokinetic characteristics are some of the leading causes of drug development failure. Therefore, poorly-soluble drugs, fragile proteins or nucleic acid products may benefit from their encapsulation in nanosized vehicles, providing enhanced solubilization, protection against degradation, and increased access to pathological compartments. A key element for the success of drug-loaded nanocarriers is their ability to either cross biological barriers themselves, or allow loaded drugs to traverse them to achieve optimal pharmacological action at pathological sites. Depending on the mode of administration, nanocarriers may have to cross different physiological barriers in their journey towards their target. In this review, the crossing of biological barriers by passive targeting strategies will be presented for intravenous delivery (vascular endothelial lining, particularly for tumor vasculature and blood brain barrier targeting), oral administration (gastrointestinal lining), and upper airway administration (pulmonary epithelium). For each specific barrier, background information will be provided on the structure and biology of the tissues involved as well as available pathways for nano-objects or loaded drugs (diffusion and convection through fenestration, transcytosis, tight junction crossing, etc.). The determinants of passive targeting - size, shape, surface chemistry, surface patterning of nanovectors - will be discussed in light of current results. Perspectives on each mode of administration will be presented. The focus will be on polymeric nanoparticles and dendrimers, although advances in liposome technology will be also reported as they represent the largest body in the drug delivery literature.

Therapist competence ratings in relation to clinical outcome in cognitive therapy of depression.

This study reports on the relationship of therapist competence to the outcome of cognitive-behavioral treatment in the National Institute of Mental Health Treatment of Depression Collaborative Research Program. Outpatients suffering from major depressive disorder were treated by cognitive-behavioral therapists at each of 3 U.S. sites using a format of 20 sessions in 16 weeks. Findings provide some support for the relationship of therapist competence (as measured by the Cognitive Therapy Scale) to reduction of depressive symptomatology when controlling for therapist adherence and facilitative conditions. The results are, however, not as strong or consistent as expected. The component of competence that was most highly related to outcome is a factor that reflects the therapist's ability to structure the treatment.

Does the gender of a patient or the gender of a therapist affect the treatment of patients with major depression?

The role of gender was examined in the process and outcome of therapy in the treatment of depressed outpatients seen in the National Institute of Mental Health Treatment of Depression Collaborative Research Program. Patients received either interpersonal therapy, cognitive-behavioral therapy, imipramine plus clinical management, or placebo plus clinical management. None of the therapist-patient by gender groupings (i.e., therapist gender, therapist-patient gender matching vs. mismatching, or patients' beliefs about whether a male or female therapist would be more helpful) were significantly related to measures of treatment process and outcome, controlling for type of treatment and severity of pretreatment depressive symptoms. Findings were duplicated when examining the effects of gender within only the psychotherapeutic modes of treatment for the groupings of therapist gender and therapist-patient gender matching versus mismatching.

Gender, type of treatment, dysfunctional attitudes, social support, life events, and depressive symptoms over naturalistic follow-up.

OBJECTIVE: The present study investigated gender differences in depressive symptoms during a naturalistic follow-up for outpatients with major depressive disorder in the National Institute of Mental Health Treatment of Depression Collaborative Research Program. Specifically, the study investigated whether gender interacted with type of treatment received, dysfunctional attitudes, life events, or social support to predict severity of depressive symptoms. In addition, aspects of these psychosocial factors (need for approval, interpersonal life events, and close friendships), hypothesized to be more salient for women, were examined to determine if they had a differential impact on level of depressive symptoms in men and women. METHOD: Assessments conducted 6, 12, and 18 months after treatment included measures of depressive symptoms, dysfunctional attitudes, current life events, and social support. Data were available for 188 subjects (134 women and 54 men). Regression analyses were conducted to examine whether gender as a main effect, or interacting with dysfunctional attitudes, life events, social support, or subtypes of these variables, predicted cross-sectional or longitudinal measures of depressive symptoms during follow-up. RESULTS: A consistent finding of the study was that over the 18 months of this naturalistic follow-up, there were no main effects for gender or any significant interactions involving gender and any of the variables of interest. The study demonstrated that life events and social support were related to severity of depressive symptoms for both genders. CONCLUSIONS: Despite differential prevalence rates of major depression for men and women, findings do not support a different process in outcome of illness for men and women.

The role of the therapeutic alliance in psychotherapy and pharmacotherapy outcome: findings in the National Institute of Mental Health Treatment of Depression Collaborative Research Program.

The relationship between therapeutic alliance and treatment outcome was examined for depressed outpatients who received interpersonal psychotherapy, cognitive-behavior therapy, imipramine with clinical management, or placebo with clinical management. Clinical raters scored videotapes of early, middle, and late therapy sessions for 225 cases (619 sessions). Outcome was assessed from patients' and clinical evaluators' perspectives and from depressive symptomatology. Therapeutic alliance was found to have a significant effect on clinical outcome for both psychotherapies and for active and placebo pharmacotherapy. Ratings of patient contribution to the alliance were significantly related to treatment outcome; ratings of therapist contribution to the alliance and outcome were not significantly linked. These results indicate that the therapeutic alliance is a common factor with significant influence on outcome.

Initial severity and differential treatment outcome in the National Institute of Mental Health Treatment of Depression Collaborative Research Program.

Random regression models (RRMs) were used to investigate the role of initial severity in the outcome of 4 treatments (cognitive-behavior therapy [CBT], interpersonal psychotherapy [IPT], imipramine plus clinical management [IMI-CM], and placebo plus clinical management [PLA-CM]) for outpatients with major depressive disorder seen in the National Institute of Mental Health Treatment of Depression Collaborative Research Program. Initial severity of depression and impairment of functioning significantly predicted differential treatment effects. A larger number of differences than previously reported were found among the active treatments for the more severely ill patients; this was due, in large part, to the greater power of the present statistical analyses.

Temporal course of change of depression.

Two hundred fifty moderately to severely depressed outpatients were randomly assigned to 16 weeks of cognitive-behavioral therapy, interpersonal psychotherapy, imipramine plus clinical management (IMI-CM), or pill placebo plus clinical management. Two hundred thirty-nine patients actually began treatment. The most rapid change in depressive symptoms occurred in the IMI-CM condition, which achieved significantly better results than the other treatments at 8 and 12 weeks on 1 or more variables. Change over the course of treatment on variables hypothesized to be most specifically affected by the respective treatments was found only in the case of pharmacotherapy, in which imipramine produced significantly greater changes on the endogenous measure at 8 and 12 weeks.

Some conceptual and statistical issues in analysis of longitudinal psychiatric data. Application to the NIMH treatment of Depression Collaborative Research Program dataset.

Longitudinal studies have a prominent role in psychiatric research; however, statistical methods for analyzing these data are rarely commensurate with the effort involved in their acquisition. Frequently the majority of data are discarded and a simple end-point analysis is performed. In other cases, so called repeated-measures analysis of variance procedures are used with little regard to their restrictive and often unrealistic assumptions and the effect of missing data on the statistical properties of their estimates. We explored the unique features of longitudinal psychiatric data from both statistical and conceptual perspectives. We used a family of statistical models termed random regression models that provide a more realistic approach to analysis of longitudinal psychiatric data. Random regression models provide solutions to commonly observed problems of missing data, serial correlation, time-varying covariates, and irregular measurement occasions, and they accommodate systematic person-specific deviations from the average time trend. Properties of these models were compared with traditional approaches at a conceptual level. The approach was then illustrated in a new analysis of the National Institute of Mental Health Treatment of Depression Collaborative Research Program dataset, which investigated two forms of psychotherapy, pharmacotherapy with clinical management, and a placebo with clinical management control. Results indicated that both person-specific effects and serial correlation play major roles in the longitudinal psychiatric response process. Ignoring either of these effects produces misleading estimates of uncertainty that form the basis of statistical tests of hypotheses.

Course of depressive symptoms over follow-up. Findings from the National Institute of Mental Health Treatment of Depression Collaborative Research Program.

We studied the course of depressive symptoms during an 18-month naturalistic follow-up period for outpatients with Major Depressive Disorder treated in the National Institute of Mental Health Treatment of Depression Collaborative Research Program. The treatment phase consisted of 16 weeks of randomly assigned treatment with the following: cognitive behavior therapy, interpersonal therapy, imipramine hydrochloride plus clinical management (CM), or placebo plus CM. Follow-up assessments were conducted at 6, 12, and 18 months after treatment. Of all patients entering treatment and having follow-up data, the percent who recovered (8 weeks of minimal or no symptoms following the end of treatment) and remained well during follow-up (no Major Depressive Disorder relapse) did not differ significantly among the four treatments: 30% (14/46) for those in the cognitive behavior therapy group, 26% (14/53) for those in the interpersonal therapy group, 19% (9/48) for those in the imipramine plus CM group, and 20% (10/51) for those in the placebo plus CM group. Among patients who had recovered, rates of Major Depressive Disorder relapse were 36% (8/22) for those in the cognitive behavior therapy group, 33% (7/21) for those in the interpersonal therapy group, 50% (9/18) for those in the imipramine plus CM group, and 33% (5/15) for those in the placebo plus CM group. The major finding of this study is that 16 weeks of these specific forms of treatment is insufficient for most patients to achieve full recovery and lasting remission. Future research should be directed at improving success rates of initial and maintenance treatments for depression.

Applying the Collaborative Study Psychotherapy Rating Scale to rate therapist adherence in cognitive-behavior therapy, interpersonal therapy, and clinical management.

Adherence of therapists to behaviors specified in cognitive-behavior therapy, interpersonal therapy, and clinical management manuals was studied. Raters used the Collaborative Study Psychotherapy Rating Scale (CSPRS) to rate therapist adherence in each of four sessions from 180 patients in the treatment phase of the National Institute of Mental Health Treatment of Depression Collaborative Research Program (TDCRP). Results indicate that therapists exhibited more behaviors appropriate to their own respective treatment approaches than to other treatment approaches. In fact, the three treatments could be discriminated almost perfectly using the CSPRS. Analysis of the psychometric properties of the CSPRS revealed high interrater reliability and high internal consistency. However, a five-component structure extracted from the intercorrelations of the CSPRS items was substantially different from a five-factor structure found in an earlier study.

Patient predictors of response to psychotherapy and pharmacotherapy: findings in the NIMH Treatment of Depression Collaborative Research Program.

OBJECTIVE: The authors investigated patient characteristics predictive of treatment response in the National Institute of Mental Health (NIMH) Treatment of Depression Collaborative Research Program. METHOD: Two hundred thirty-nine outpatients with major depressive disorder according to the Research Diagnostic Criteria entered a 16-week multicenter clinical trial and were randomly assigned to interpersonal psychotherapy, cognitive-behavior therapy, imipramine with clinical management, or placebo with clinical management. Pretreatment sociodemographic features, diagnosis, course of illness, function, personality, and symptoms were studied to identify patient predictors of depression severity (measured with the Hamilton Rating Scale for Depression) and complete response (measured with the Hamilton scale and the Beck Depression Inventory). RESULTS: One hundred sixty-two patients completed the entire 16-week trial. Six patient characteristics, in addition to depression severity previously reported, predicted outcome across all treatments: social dysfunction, cognitive dysfunction, expectation of improvement, endogenous depression, double depression, and duration of current episode. Significant patient predictors of differential treatment outcome were identified. 1) Low social dysfunction predicted superior response to interpersonal psychotherapy. 2) Low cognitive dysfunction predicted superior response to cognitive-behavior therapy and to imipramine. 3) High work dysfunction predicted superior response to imipramine. 4) High depression severity and impairment of function predicted superior response to imipramine and to interpersonal psychotherapy. CONCLUSIONS: The results demonstrate the relevance of patient characteristics, including social, cognitive, and work function, for prediction of the outcome of major depressive disorder. They provide indirect evidence of treatment specificity by identifying characteristics responsive to different modalities, which may be of value in the selection of patients for alternative treatments.

Mode-specific effects among three treatments for depression.

In the NIMH Treatment of Depression Collaborative Research Program (TDCRP), 250 depressed outpatients were randomly assigned to interpersonal psychotherapy, cognitive-behavioral therapy, imipramine plus clinical management, or pill placebo plus clinical management treatments. Although all treatments demonstrated significant symptom reduction with few differences in general outcomes, an important question concerned possible effects specific to each treatment. The therapies differ in rationale and procedures, suggesting that mode-specific effects may differ among treatments, each of which was precisely specified, applied appropriately, and shown to be discriminable. Outcome measures were selected for presumed sensitivity to the different treatments. Findings provided only scattered and relatively insubstantial support for mode-specific differences. None of the therapies produced consistent effects on measures related to its theoretical origins.

Personality disorders and treatment outcome in the NIMH Treatment of Depression Collaborative Research Program.

The authors investigated the relationship between personality disorders and treatment outcome in the National Institute of Mental Health Treatment of Depression Collaborative Research Program, which involved 239 outpatients with major depressive disorder randomly assigned to one of four 16-week treatment conditions. Patients with personality disorders (74% of the sample) had a significantly worse outcome in social functioning than patients without personality disorders and were significantly more likely to have residual symptoms of depression. There were no significant differences in work functioning or in mean depression scores at treatment termination. Outcome was similar for patients in the different clusters of personality disorders.

National Institute of Mental Health Treatment of Depression Collaborative Research Program. General effectiveness of treatments.

We investigated the effectiveness of two brief psychotherapies, interpersonal psychotherapy and cognitive behavior therapy, for the treatment of outpatients with major depression disorder diagnosed by Research Diagnostic Criteria. Two hundred fifty patients were randomly assigned to one of four 16-week treatment conditions: interpersonal psychotherapy, cognitive behavior therapy, imipramine hydrochloride plus clinical management (as a standard reference treatment), and placebo plus clinical management. Patients in all treatments showed significant reduction in depressive symptoms and improvement in functioning over the course of treatment. There was a consistent ordering of treatments at termination, with imipramine plus clinical management generally doing best, placebo plus clinical management worst, and the two psychotherapies in between but generally closer to imipramine plus clinical management. In analyses carried out on the total samples without regard to initial severity of illness (the primary analyses), there was no evidence of greater effectiveness of one of the psychotherapies as compared with the other and no evidence that either of the psychotherapies was significantly less effective than the standard reference treatment, imipramine plus clinical management. Comparing each of the psychotherapies with the placebo plus clinical management condition, there was limited evidence of the specific effectiveness of interpersonal psychotherapy and none for cognitive behavior therapy. Superior recovery rates were found for both interpersonal psychotherapy and imipramine plus clinical management, as compared with placebo plus clinical management. On mean scores, however, there were few significant differences in effectiveness among the four treatments in the primary analyses. Secondary analyses, in which patients were dichotomized on initial level of severity of depressive symptoms and impairment of functioning, helped to explain the relative lack of significant findings in the primary analyses. Significant differences among treatments were present only for the subgroup of patients who were more severely depressed and functionally impaired; here, there was some evidence of the effectiveness of interpersonal psychotherapy with these patients and strong evidence of the effectiveness of imipramine plus clinical management. In contrast, there were no significant differences among treatments, including placebo plus clinical management, for the less severely depressed and functionally impaired patients.

Conceptual and methodological issues in comparative studies of psychotherapy and pharmacotherapy, II: Nature and timing of treatment effects.

This is the second of two articles on the conceptual and methodological problems involved in comparing the effectiveness of drugs and psychotherapy in the treatment of mental disorders. Part II focuses on differences between psychotherapy and pharmacotherapy in the nature of treatment effects and related goals for treatment, differences in the time course of treatment effects, and potential sources of bias in the research setting. In designing comparative studies of psychotherapy and pharmacotherapy, investigators should address methodological choices explicitly and consider the implications for interpretation of findings.

Conceptual and methodological issues in comparative studies of psychotherapy and pharmacotherapy, I: Active ingredients and mechanisms of change.

There has recently been an increased focus on comparing the effectiveness of drugs and psychotherapy in the treatment of mental disorders. The marked differences between these two treatment forms raise many conceptual and methodological problems for the investigator. In a two-part series, the authors discuss a number of these conceptual issues and their implications for research design, implementation, and interpretation of findings. Part I focuses on differences in the active ingredients and hypothesized mechanisms of change of psychotherapy and pharmacotherapy. Issues addressed include the need for standardization of treatments, adequate delivery of treatments, and controlling for factors other than the active ingredients of each treatment.