Nafion has been the mostly used perfluorosulfonated proton exchange membrane (PEM) in fuel cell. Although a number of problems remain to be resolved on the application of Nafion as a PEM, a less expensive alternative PEM has not been found mainly because of its high proton conductivity. Therefore, much effort has been invested to modify it or find a better and inexpensive material. The exploration of the methods to counter degradation and aging of Nafion is also an important direction of research. In this work, the behavior of PEG in Nafion is investigated with solid state NMR spectroscopy. A series of samples with different PEG sizes and concentrations in Nafion was prepared and the variable temperature proton spectra and longitudinal relaxation times (T1) were measured on two spectrometers. Some interesting findings were made, e.g., the 1H chemical shift of water in concentrated PEG solution decrease while its T1 increase, the higher the concentration of PEG, the larger the increase (of water 1H chemical shift) or decrease (of water 1H T1). These findings provide valuable information on further improving the performance of Nafion in proton conductivity and durability.

Perfluororated proton exchange membrane Nafion is the mostly used type of ion exchange membrane in fuel cells. Over the past decades, various studies have been carried out on their structures at different scales, proton conduction mechanism, electrochemical performance, thermal and mechanical properties etc, but many problems are still open, such as the precise picture of proton conduction, degradation and aging of the membrane, even the distribution of pores and channels etc. Because membrane degradation is crucial for practical operation of fuel cells and its understanding offers insights for developing new generation membranes, more and more attention is paid to this issue. Methanol is used in direct methanol fuel cells (DMFC) and alcohols are sensitive to the structure and dynamics of Nafion. In addition, aqueous solutions of alcohols are known to have special mesoscopic structures. Therefore, this thesis employs the aqueous solution of methanol as a probe and investigate the physicochemical mechanism of the degradation of Nafion 117 by means of solid state NMR spectra, relaxation, exchange, diffusion and micro-imaging. A series of methanol-water binary solution samples covering the entire range of concentration (0% ~ 99%(w/w)) were prepared and the 1H,17O NMR spectra,T1¡BT2, exchange rate, diffusion coefficient of these samples in bulk and in Nafion were measured. In bulk samples, the OH peak of water and that of methanol could be resolved with concentration at or above 40% (w/w). The microscopic and mesoscopic structure and dynamics of methanol solutions (in bulk) were subsequently investigated with variable temperature and diffusion experiments. By measuring the variable temperature 1H and 17O spectra, T1, T2, diffusion and micro-images of the methanol solutions in Nafion 117, the structure and dynamics of methanol solutions in bulk and in Nafion 117 were then compared. Based on these data, the structure an dynamics of Nafion 117 and the correlations between methanol and proton conduction and membrane degradation are discussed. The results of this work provides valuable reference for further understanding the structure, dynamics and degradation of Nafion and their relationship with proton conduction.

This dissertation considers a class of closely related NP-hard otpimization problems on graphs that arise in many important applications, including network-based data mining, analysis of the stock market, social networks, coding theory, fault diagnosis, molecular biology, biochemistry and genomics. In particular, the problems of interest include the classical maximum independent set problem (MISP) and maximum clique problem (MCP), their vertex-weighted vesrions, as well as novel optimization models that can be viewed as practical relaxations of their classical counterparts. The concept of clique has been a popular instrument in analysis of networks, and is, essentially, an idealized model of a “closely connected group”, or a cluster. But, at the same time, the restrictive nature of the definition of clique makes the clique model impractical in many applications. This motivated the development of clique relaxation models that relax different properties of a clique. On the one hand, while still possessing some clique-like properties, clique relaxations are not as “perfect” as cliques; and on the other hand, they do not exhibit the disadvantages associated with a clique. Using clique relaxations allows one to compromise between perfectness and flexibility, between ideality and reality, which is a usual issue that an engineer deals with when applying theoretical knowledge to solve practical problems in industry. The clique relaxation models studied in this dissertation were first proposed in the literature on social network analysis, however they have not been well investigated from a mathematical programming perspective. This dissertation considers new techniques for solving the MWISP and clique relaxation problems and investigates their effectiveness from theoretical and computational perspectives. The main results obtained in this work include (i) developing a scale-reduction approach for MWISP based on the concept of critical set and comparing it theoretically with other approaches; (ii) obtaining theoretical complexity results for clique relaxation problems; (iii) developing algorithms for solving the clique relaxation problems exactly; (iv) carrying out computational experiments to demonstrate the performance of the proposed approaches, and, finally, (v) applying the obtained theoretical results to several real-life problems.

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Thèse de doctorat : Génie des matériaux : Villeurbanne, INSA : 2002. / Titre provenant de l'écran-titre. Bibliogr. p.149-158.

Reproduction de : Thèse de doctorat : Informatique : Clermont Ferrand 2 : 2005. Reproduction de : Thèse de doctorat : Informatique : Université de Sherbrooke : 2005. / Thèse en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. p.141-149.

Thesis (Ph. D.)--Lehigh University, 2003. / Includes bibliographical references and vita.

The effectiveness of progressive relaxation training in decreasing the severity of neuroleptic-induced tardive dyskinesia (TD) was examined in the current study. Three residents at a county-owned nursing home who had been receiving neuroleptic medications for a number of years to treat severe mental illness participated in this study. A multiple baseline across subjects design was used to evaluate the effect of progressive relaxation training on the participant's orofacial TD symptomatology. The severity of each participant's orofacial TD was observed to improve when the intervention was introduced. Treatment integrity and IOA data that were collected indicate that the intervention was implemented at a high level of fidelity and that data were reliable. Thus, a clear functional relationship was established between progressive relaxation training and severity of orofacial TD in this study. Although the present study was preliminary in nature, the results that were obtained provide a basis upon which to develop a behavioral treatment protocol for managing TD.

Stress and anxiety during pregnancy predict perinatal complications over the course of pregnancy and labor as well as premature birth and low infant birth weight. The current study examined whether relaxation training provided to women at the beginning of the 2nd trimester could reduce stress and anxiety and assessed the impact of the intervention on perinatal complications, premature delivery, and infant outcomes at birth. Twenty-six moderately anxious pregnant women between 14 and 20 weeks gestation participated in the treatment study. Women completed a baseline laboratory assessment that involved questionnaires and a psychophysiological assessment. They were randomized to receive either six weeks of relaxation training or a list of tips for reducing stress (control). Women repeated the laboratory tasks post-treatment (Time 2) and again between 34 and 36 weeks gestation (Time 3). The treatment condition did not lead to greater mood change than the control condition at either Time 2 or 3. Several analyses, however, suggest relaxation training has the potential for reducing negative mood and complications over the course of pregnancy. Moderator analyses also revealed the treatment more efficacious for those with greater physiological flexibility.

Previous studies have shown positive results on the use of music as postoperative pain relief. Quantitative studies have examined the effect of music on rated pain and otherparameters such as anxiety, relaxation and blood-pressure. The purpose of this study was to investigate the expectations and experiences of patients and nurses onimplementing music as postoperative pain relief in an orthopedic unit Qualitative design and semi-structured interviews were used to examine expectations and experiences. Five patients and five nurses in the unit were interviewed. Four themes developed during the data-analysis. These themes were “Expectations on music as postoperative pain relief”, “Experiences of music as postoperative pain relief”,“Effects of music as postoperative pain relief” and “Continued implementation of musicas postoperative pain relief”. A general theme was distraction. Both patients and nurses described the distracting ability of music. Music distracted the patients from both painand the unfamiliar environment and provided relaxation. According to the results of this study there is a connection between the distracting effect of the music and pain relief. More research needs to be done to examine how musicaffects the human body and mind.