1,378 research outputs found

    The development of a senior unit operations laboratory on the supercritical extraction of solid naphthalene with supercritical carbon dioxide

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    A Senior level Undergraduate Unit Operations Laboratory experiment was developed for the extraction of Naphthalene with supercritical Carbon Dioxide. A Supercritical Extraction Screening System purchased from Autoclave Engineers of Erie, Pennsylvania was modified slightly for use as the laboratory equipment. The experiment consists of extracting solid naphthalene from a sand bed in a fixed bed extractor and determining the mass transfer coefficient for the unit. The lab has been designed to allow the students to develop their own experimental plan without much direct input. The experimental outline provided for the students primarily focuses on information needed for safe and proper operation of the equipment. The discussion questions the students are asked to consider, however, have been developed to provide some guidance on how the experimental plan should be developed. Additionally, these questions focus the students onto some of the other concerns of Supercritical Fluid Extraction like heat transfer and material handling. Finally, the experiment allows the student to apply basic thermodynamic principles to real world problems like the prediction of unavailable physical properties near the critical point. These predictions are necessary to do calculations related to scale-up and equipment performance on Supercritical Fluid Extraction processes. A computer program written in BASIC that utilizes the Peng-Robinson equation of state with mixing rules that use a single binary interaction parameter is also included

    The development of h Homogeneous nucleation rate model for thermoplastic foams based on a molecular partition function and Fickian diffusion

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    An improved homogeneous nucleation rate model for thermoplastic foams has been developed. This model does not rely on experimentally determined parameters and only uses pure component physical property data and a binary diffusion coefficient. This model, like those derived from classical nucleation theory, is made up of two parts, one that determines the size of the energy barrier in the nucleation process and one that estimates the forward rate of the process. A statistical-mechanical approach was used to create an energy term that is based on a molecular partition function. In this approach, the bulk phase (polymer and blowing, agent mixture) of the system is treated as a regular solution and the potential energy of this phase is estimated from regular solution theory. The rate component of the model is obtained by utilizing a diffusion-based model derived from Fick\u27s law, Additional approaches including a diffusion only based approach, a fluctuation theory based approach, and a lattice model based approach were all unsuccessfully investigated. The predictions obtained from the model have been compared to a polymethylmethacrylate/carbon system with limited success. Althoulgh the model results do not match the experimental data, there is a significant improvement over the results obtained from current models available in the literature. The data is limited to the one system described above as there was significant evidence of heterogeneous nucleation in most other systems identified in the literature. Finally, the work also provides a comprehensive review of the literature on foam nucleation in thermoplastics. The review covers both homogeneous and heterogeneous models and looks at results obtained experimentally and theoretically. This review clearly identifies the need for an improved nucleation model that is not dependent on experimental parameters like the one developed in this work

    History of on-orbit satellite fragmentations

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    The causes of on-orbit fragmentations are varied and may be intentional or accidental. The cause of many fragmentations remains unknown. While a few cases are currently under investigation as on-orbit collision candidates, man is directly responsible for the vast majority of artificial debris polluting the near-Earth space environment. It should be emphasized that the number of fragments listed with each event in this document represent only those debris officially cataloged by NORAD. Each known on-orbit satellite fragementation is described within this document in module format. Also listed are pertinent characteristics of each fragmentation event. Comments regarding the nature of the satellite and additional details of the events are given

    Efficacy of a ML336 Derivative Against Venezuelan and Eastern Equine Encephalitis Viruses

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    Currently, there are no licensed human vaccines or antivirals for treatment of or prevention from infection with encephalitic alphaviruses. Because epidemics are sporadic and unpredictable, and endemic disease is common but rarely diagnosed, it is difficult to identify all populations requiring vaccination; thus, an effective post-exposure treatment method is needed to interrupt ongoing outbreaks. To address this public health need, we have continued development of ML336 to deliver a molecule with prophylactic and therapeutic potential that could be relevant for use in natural epidemics or deliberate release scenario for Venezuelan equine encephalitis virus (VEEV). We report findings from in vitro assessments of four analogs of ML336, and in vivo screening of three of these new derivatives, BDGR-4, BDGR-69 and BDGR-70. The optimal dosing for maximal protection was observed at 12.5 mg/kg/day, twice daily for 8 days. BDGR-4 was tested further for prophylactic and therapeutic efficacy in mice challenged with VEEV Trinidad Donkey (TrD). Mice challenged with VEEV TrD showed 100% and 90% protection from lethal disease when treated at 24 and 48 h post-infection, respectively. We also measured 90% protection for BDGR-4 in mice challenged with Eastern equine encephalitis virus. In additional assessments of BDGR-4 in mice alone, we observed no appreciable toxicity as evaluated by clinical chemistry indicators up to a dose of 25 mg/kg/day over 4 days. In these same mice, we observed no induction of interferon. Lastly, the resistance of VEEV to BDGR-4 was evaluated by next-generation sequencing which revealed specific mutations in nsP4, the viral polymerase

    Is there still a place for the concept of therapeutic regression in psychoanalysis?

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    The author uses his own failure to find a place for the idea of therapeutic regression in his clinical thinking or practice as the basis for an investigation into its meaning and usefulness. He makes a distinction between three ways the term ‘regression’ is used in psychoanalytic discourse: as a way of evoking a primitive level of experience; as a reminder in some clinical situations of the value of non-intervention on the part of the analyst; and as a description of a phase of an analytic treatment with some patients where the analyst needs to put aside normal analytic technique in order to foster a regression in the patient. It is this third meaning, which the author terms “therapeutic regression” that this paper examines, principally by means of an extended discussion of two clinical examples of a patient making a so-called therapeutic regression, one given by Winnicott and the other by Masud Khan. The author argues that in these examples the introduction of the concept of therapeutic regression obscures rather than clarifies the clinical process. He concludes that, as a substantial clinical concept, the idea of therapeutic regression has outlived its usefulness. However he also notes that many psychoanalytic writers continue to find a use for the more generic concept of regression, and that the very engagement with the more particular idea of therapeutic regression has value in provoking questions as to what is truly therapeutic in psychoanalytic treatment

    The role of empathy in psychoanalytic psychotherapy: A historical exploration

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    Empathy is one of the most consistent outcome predictors in contemporary psychotherapy research. The function of empathy is particularly important for the development of a positive therapeutic relationship: patients report positive therapeutic experiences when they feel understood, safe, and able to disclose personal information to their therapists. Despite its clear significance in the consulting room and psychotherapy research, there is no single, consensual definition of empathy. This can be accounted by the complex and multi-faceted nature of empathy, as well as the ambiguous and conflicting literature surrounding it. This paper provides a historical exploration of empathy and its impact on the therapeutic relationship across the most influential psychoanalytic psychotherapies: classic psychoanalysis, person-centered therapy and self-psychology. By comparing the three clinical schools of thought, the paper identifies significant differences in the function of transference and therapist’s role. Then, drawing on the different clinical uses of empathy, the paper argues that the earlier uses of empathy (most notably through Jaspers’ and Freud’s writings) are limited to its epistemological (intellectual or cognitive) features, whilst person-centered and self-psychology therapies capitalise on its affective qualities. Finally, the paper provides a rationale for further study of the overarching features of empathy in contemporary psychotherapy research

    The reliability of two visual motor integration tests used with children

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    Occupational therapists often assess the visual motor integration (VMI) skills of children and young people. It is important that therapists use tools with strong psychometric properties. This study aims to examine the reliability of 2 VMI tests. Ninety-two children between the ages of 5 and 17 years (response rate of 31%) completed 2 VMI tests: the Developmental Test of Visual Motor Integration (DTVMI) and the Full Range Test of Visual Motor Integration (FRTVMI). Cronbach\u27s alpha coefficient was used to examine the internal consistency of the 2 VMI tests whereas Spearman\u27s rho correlation was used to evaluate the test&ndash;retest reliability, intrarater reliability, and interrater reliability of the 2 VMI tests. The Cronbach\u27s alpha coefficient for the DTVMI was .82 and .72 for the FRTVMI. The test&ndash;retest reliability coefficient was .73 (p = .000) for the DTVMI and .49 (p = .05) for the FRTVMI. The interrater correlation was significant for both the DTVMI at .94 (p = .000) and FRTVMI at .68 (p = .001). The DTVMI intrarater reliability correlation result was .90 (p = .000) and the FRTVMI at .85 (p = .000). Overall, the DTVMI exhibited a higher level of reliability than the FRTVMI. Both VMI tests appear to exhibit reasonable levels of reliability and are recommended for use with children and young people.<br /
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