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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Asymmetric Syntheses of Analogs of Kainic Acid

Wang, Wentian 02 November 2012 (has links)
Kainic acid has been used for nearly 50 years as a tool in neuroscience due to its pronounced neuroexcitatory properties. However, the significant price increase of kainic acid resulting from the disruption in the supply from its natural source, the alga Digenea Simplex, as well as inefficient synthesis of kainic acid, call for the exploration of functional mimics of kainic acid that can be synthesized in a simpler way. Aza kainoids analog could be one of them. The unsubstituted aza analog of kainoids has demonstrates its ability as an ionotropic glutamate receptor agonist and showed affinity in the chloride dependent glutamate (GluCl) binding site. This opened a question of the importance of the presence of one nitrogen or both nitrogens in the aza kainoid analogs for binding to glutamate receptors. Therefore, two different pyrrolidine analogs of kainic acid, trans-4-(carboxymethyl)pyrrolidine-3-carboxylic acid and trans-2-carboxy-3-pyrrolidineacetic acid, were synthesized through multi-step sequences. The lack of the affinity of both pyrrolidine analogs in GluCl binding site indicated that both nitrogens in aza kainoid analogs are involved in hydrogen bonding with receptors, significantly enhancing their affinity in GluCl binding site. Another potential functional mimic of kainic acid is isoxazolidine analogs of kainoids whose skeleton can be constituted directly via a 1, 3 dipolar cycloaddition as the key step. The difficulty in synthesizing N-unsubstituted isoxazolidines when applying such common protecting groups as alkyl, phenyl and benzyl groups, and the requirement of a desired enantioselectivity due to the three chiral ceneters in kainic acid, pose great challenges. Hence, several different protected nitrones were studied to establish that diphenylmethine nitrone may be a good candidate as the dipole in that the generated isoxazolidines can be deprotected in mild conditions with high yields. Our investigations also indicated that the exo/endo selectivity of the 1, 3 dipolar cycloaddition can be controlled by Lewis acids, and that the application of a directing group in dipolarophiles can accomplish a satisfied enantioselectivity. Those results demonstrated the synthesis of isoxazoldines analogs of kainic acid is very promising.
2

Mark Mosher's reconstruction of the development of the woodworkers union in the Alberni Valley 1935-1950 : a participant's history

McIntosh, Jean Elizabeth January 1987 (has links)
This thesis presents a participant's history of the development of the woodworkers' union in the Alberni Valley of British Columbia during the period 1935 to 1950. It is developed through Mosher's own accounts, which are treated as narratives, as the way of most effectively presenting his "insiders point of view". Mosher's interpretation, from his position as a logger, a local union leader, and a Communist Party member, adds to our understanding of the union movement by providing the perspective from the Left and information on the processes of unionization. In spite of the central position held by the union movement in the social structure of British Columbia, and the importance of the IWA within that movement, both have been under researched. Mosher's accounts are given in the context of the documentary history of the union movement and the IWA, and his narratives create a challenging interpretation in response to those established accounts. Comparisons are drawn between the interpretations of the same issues given by Mosher and by the documentary sources. Mosher's accounts express the themes and values important to his alternative history, such as the need for a union and the leadership role of the Communist Party in improving work conditions, which he claims has not before been acknowledged. This thesis is based on the assumption that there is no one true version of history. History is viewed as a process in which differing interpretations continually add to our overall understanding of a subject. / Arts, Faculty of / Anthropology, Department of / Graduate
3

Synthèse stéréosélective d'hétéroaryl alcools et alanines

Pop, Laura Ancuta 27 October 2011 (has links) (PDF)
Cette thèse présente la synthèse stéréosélective de plusieurs nouveaux acides aminés et alcools secondaires en utilisant la biocatalyse. Le travail est divisé en deux parties principales. La première partie est consacrée à la synthèse stéréosélective des alanines hétéroaryles en utilisant deux différents biocatalyseurs avec le même énantiopréférence, l'aminocatalyse I et la levure de boulanger (Saccharomyces cerevisiae). A l'aide de ces deux biocatalyseurs, les L-alanines ont été obtenus avec des excès énantiomériques et rendements élevé. La deuxième partie est consacrée à la synthèse des deux énantiomètres des alcools secondaires (hétéro)aryles en utilisant les lipases comme biocatalyseurs. Cette partie est divisée en deux sous-chapitres, un pour la synthèse stéréosélective de différents (thiazole-2-yl) - méthanols C-substitués et leurs dérivés acylés. Ces composés ont été obtenus par l'acylation enzymatique stéréosélective des alcools racémiques et par l'hydrolise enzymatique de leurs dérivés acylés.
4

Synthèse stéréosélective d'hétéroaryl alcools et alanines / Stereoselective synthesis of heteroaryl alcohols and alanines

Pop, Laura Ancuta 27 October 2011 (has links)
Cette thèse présente la synthèse stéréosélective de plusieurs nouveaux acides aminés et alcools secondaires en utilisant la biocatalyse. Le travail est divisé en deux parties principales. La première partie est consacrée à la synthèse stéréosélective des alanines hétéroaryles en utilisant deux différents biocatalyseurs avec le même énantiopréférence, l'aminocatalyse I et la levure de boulanger (Saccharomyces cerevisiae). A l'aide de ces deux biocatalyseurs, les L-alanines ont été obtenus avec des excès énantiomériques et rendements élevé. La deuxième partie est consacrée à la synthèse des deux énantiomètres des alcools secondaires (hétéro)aryles en utilisant les lipases comme biocatalyseurs. Cette partie est divisée en deux sous-chapitres, un pour la synthèse stéréosélective de différents (thiazole-2-yl) - méthanols C-substitués et leurs dérivés acylés. Ces composés ont été obtenus par l'acylation enzymatique stéréosélective des alcools racémiques et par l'hydrolise enzymatique de leurs dérivés acylés. / This PhD thesis presents the stereoselecticve synthesis of several novel amino acids and secondary alcohols using biocatalysis. The work is divided in two main parts.The first part is dedicated to the stereoselective synthesis of novel heteroaryl alanines using two different biocatalysts with the same enantiopreference, the aminoacylase I and the baker's yeast (Saccharomyces cerevisiae). Using these two biocatalysts the L-alanines were obtained with a high enantiometric excess and yields.The second part is dedicated to the syntehsis of the txo enantiomers of the novel (hetero)aryl secondary alcohols using lipases as the biocatalysts. This part is divided in two sub-chapters, one for the stereoselective synthesis of (S)- and (R)-1-aryl-3-chloro propanols and the other for the streoselective synthesis of different (thiazole-2-yl)-methanols C-substituted and their acylated derivatives. These compounds were obtained by the stereoselective enzymatic acylation of the racemic alcohols and the enzymatic hydrolisis ot their acylatic derivatives.
5

Pharmacochimie de nouveaux inhibiteurs contre les infections à rhinovirus / Pharmacochemistry of new inhibitors against rhinovirus infections

Da Costa, Laurène 19 October 2017 (has links)
Le rhinovirus (RV) est connu pour être l'étiologie de plus de la moitié des rhumes bénins. Ces virus ont également été associés à des pathologies respiratoires beaucoup plus graves (asthme, bronchopneumopathie chronique obstructive (BPCO) et mucoviscidose). Le développement d'inhibiteurs de décapsidation du virus, appelés agents « capsid-binders », est ainsi devenu une priorité pour de nombreux laboratoires de recherche. Dans ce contexte, une classe d’inhibiteurs se liant au sein de la poche hydrophobe de la protéine capsidaire VP1 a été développée par notre équipe au travers d’une stratégie radicalaire médiée par le TDAE (Tétrakis(DiméthylAmino)Ethylène). Dans le but de poursuivre les investigations sur le hit LPCRW_0005, un travail de pharmacochimie a été entrepris selon deux approches. Dans un premier temps, une optimisation de la taille du LPCRW_0005 a été envisagée par un allongement du squelette chimique. La conception de ces molécules a été guidée par l’utilisation de modélisation moléculaire via la réalisation de docking rigide ligand/protéine. La synthèse de nombreux composés et leur évaluation in vitro, ont permis de mieux apprécier le potentiel biologique de ce type de dérivés. L’identification de la configuration active du centre stéréogène porté par le linker alcool a été rendue possible par la séparation énantiosélective de certains inhibiteurs suivie d’une caractérisation basée sur un protocole de Mosher. Dans un second temps, une étude comparative des séquences primaires protéiques, nous ont conduits à concevoir de nouveaux composés afin de développer des « capsid-binders » à plus large spectre d'action. / Rhinovirus (RV), virus of Picornaviridae family, is known to be the aetiology of more than half of the common cold. Through advances in molecular biology, the rhinoviruses have been associated with much more serious respiratory pathologies (asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis). So, the development of viral attachment and/or uncoating inhibitors named « capsid-binders » molecules has become a priority for many research laboratories. In this context, a class of inhibitors binding into a hydrophobic pocket of the VP1 capsid protein has been identified by our team through a TDAE strategy. In order to follow the investigations on the LPCRW_0005 hit, a pharmacochemistry work was begun according to two approaches. Initially, an optimisation of the LPCRW_0005 size was envisaged by an extension of the scaffold via various pallado-catalyzed cross-coupling reactions. The design of these molecules was guided by the use of molecular modeling via a rigid ligand/protein docking. The synthesis of many compounds and their in vitro biological evaluation on HeLa cells infected with the rhinovirus 14 (RV-B14), refined our knowledge about the biological potential of such a scaffold. The enantioselective separation of some inhibitors followed by a Mosher’s protocol allowed us to identify the active configuration of the alcohol linker. Finally, a comparative study of protein primary sequences as well as drug design, led us to design and develop more potent broad-spectrum capsid-binders.
6

The midlife crisis, gender, and social science in the United States, 1970-2000

Schmidt, Susanne Antje January 2018 (has links)
This thesis provides the first rigorous history of the concept of midlife crisis. It highlights the close connections between understandings of the life course and social change. It reverses accounts of popularization by showing how an idea moved from the public sphere into academia. Above all, it uncovers the feminist origins of the concept and places this in a historically little-studied tradition of writing about middle age that rejected the gendered "double standard of aging." Constructions of middle age and life-planning were not always oppressive, but often used for feminist purposes. The idea of midlife crisis became popular in the United States with journalist Gail Sheehy's Passages (1976), a critique of Erik Erikson's male-centered model of ego development and psychoanalytic constructions of gender and identity more generally. Drawing on mid-century notions of middle life as the time of a woman's entry into the public sphere, Sheehy's midlife crisis defined the onset of middle age, for men and women, as the end of traditional gender roles. As dual-earner families replaced the male breadwinner model, Passages circulated widely, read by women and men of different generations, including social scientists. Three psychoanalytic experts-Daniel Levinson, George Vaillant, and Roger Gould-rebutted Sheehy by putting forward a male-only concept of midlife as the end of a man's family obligations; they banned women from reimagining their lives. Though this became the dominant meaning of midlife crisis, it was not universally accepted. Feminist scholars, most famously the psychologist and ethicist Carol Gilligan, drew on women's experiences to challenge the midlife crisis, turning it into a sign of emotional instability, immaturity, and egotism. Resonating with widespread understandings of mental health and social responsibility, and confirmed by large-scale surveys in the late 1990s, this relegated the midlife crisis to a chauvinist cliché. It has remained a contested concept for negotiating the balances between work and life, production and reproduction into the present day.

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