VictorJuiz/thesis huggingface dataset:
Magnetic properties of thiogermanate open-framework materials

A history of thiogermanate materials leading to the development of novel open-framework frameworks is detailed. The materials under investigation have the chemical formula T$\rm\sb2MGe\sb4S\sb{10}$ where T is a templating cation, tetramethylammonium (TMA$\sp+$), Cs$\sp+$ or Rb$\sp+$ and M is a divalent transition metal cation, Fe(II), Mn(II) or Zn(II). The Ge$\rm\sb4S\sb{10}\sp{4-}$ adamantanoid cluster can be isolated as a water-soluble precursor and subsequently reacted with metal salts at room temperature conditions. Raman spectroscopy, Thermal Gravimetric Analysis (TGA) and Powder X-ray Diffraction (PXRD) are used to verify the purity and structure of the materials obtained, and Rietveld refinement of PXRD data was successfully used to obtain the crystal structure of Cs$\rm\sb2MnGe\sb4S\sb{10}\cdot xH\sb2$O. The magnetic properties of the materials are examined utilizing Electron Paramagnetic Resonance (EPR), bulk susceptibility measurements, and M ossbauer spectroscopy. Susceptibility measurements indicate that these materials are nearly perfect paramagnets down to 2K, though the presence of weak anti-ferromagnetic interactions could exist.
Gene trap studies of the mouse genome and embryonic development

In recent years, gene trap insertional mutagenesis strategy has been developed and successfully used to disrupt and study developmentally regulated genes in the mouse embryos. Using a gene trap approach, two independent mouse embryonic stem (ES) cell clones were identified and investigated for developmental expression pattern, disrupted gene sequences and phenotypic effects. The strategy made use of a promoterless 'lacZ' reporter gene to disrupt and mark genomic loci and to determine the expression pattern of genes. I193 and R140 gene trapped ES cell clones were isolated in a retinoic acid (RA) response screen and were then characterized by myself as described in this dissertation. The RA-induced Dr repetitive element and RA-induced 'Aquarius ' gene were cloned from the I193 clone. Dr elements are highly similar in sequence, show peculiar structural features and are expressed in a spatially restricted manner. The expression of Dr transcripts seems to be part of an ES cell differentiation program induced by RA. 'Aquarius' is a novel gene with weak similarity to RNA-dependent RNA polymerases (RRP) of the murine hepatitis viruses and it contains an RRP motif. During embryonic development, 'Aquarius' is expressed in mesoderm, neural crest and neural crest-derived tissues, and in neuroepithelium. Mice homozygous for the 'Aquarius' gene trapped allele are viable, are normal in size and weight, and breed normally. The gene trapped locus, designated 'myocyte maintenance' ('mym'), was identified and characterized in the R140 clone. ' mym' is expressed in heart, limbs, gut, meninges and choroid plexus. The disrupted 'mym' locus was transmitted through the mouse germ line on to different genetic backgrounds. Homozygous mutant embryos died during midgestation due to heart failure. Myocardial wall and trabeculae were found to be diminished in thickness and size, and were hypoplastic. In mutant myocytes the organization of actin-myosin filaments and cell junctions were disrupted and the expression of myosin light chain isoforms was deregulated. ' mym' is required for the maintenance and organization of heart myocytes during midgestation development. The results presented in this thesis indicate the facility of gene trapping to identify and study developmentally regulated mammalian genes and genetic elements.
Variability in cytochrome P450 2D6 and 1A2 activities during treatment with selective serotonin reuptake inhibitor antidepressants, relevance for antipsychotic pharmacokinetics and side effects

'Background'. The selective serotonin reuptake inhibitor (SSRI) antidepressants paroxetine, sertialine and fluvoxamine inhibit CYP2D6 and CYP1A2 isozymes in vitro. CYP2D6 and CYP1A2 contribute to disposition of 30 or more frequently used medications including antipsychotics. The studies presented in this thesis tested the effect of paroxetine on CYP2D6 activity in vivo and its clinical importance in relation to perphenazine (a CYP2D6 substrate) pharmacokinetics and side effects. The effects of different SSRIs on CYP2D6 and CYP1A2 activities were also compared in vivo. 'Methods. Study 1': Eight healthy volunteers with an extensive metabolizer (EM) phenotype for CYP2D6 were administered a single oral dose of perphenazine (0.11 mg/kg) or placebo in a randomized double blind manner. Perphenazine plasma concentration and side effects were assessed for eight hours after drug administration. Subsequently, subjects were administered paroxetine (20 mg/day) for 10 days and test sessions with perphenazine and placebo were repeated. 'Study 2': Patients and healthy volunteers were treated with paroxetine (17.7 mg/day ± 4.4) (mean ± SD), sertraline (93.5 mg/day ± 26.4) or fluvoxamine (83.3 mg/day ± 25.0) for 5 to 74 days. AD subjects had an EM phenotype for CYP2D6 and received a single oral dose of dextromethorphan (30 mg) and caffeine (100 mg) before and after SSRI treatment. The log 'O'-demethylation ratio (ODMR) of dextromethorphan and the caffeine metabolic ratio in overnight urine were used as in vivo indices of the CYP2D6 and CYP1A2 isozyme activities, respectively. 'Results. Study 1': Perphenazine peak plasma concentration increased 2- to 13-fold after paroxetine treatment (p < 0.01). This was associated by a significant increase in antipsychotic side effects (e.g. akathisia and sedation) (p < 0.05). 'Study 2': The baseline !log ODMR! significantly decreased after paroxetine treatment (from 2.28 ± 0.37 to 1.13 ± 0.44) (p < 0.05). Sertraline treatment caused only a modest change in !log ODMR! (from 2.33 ± 0.45 to 2.19 ± 0.62) (p < 0.05). Fluvoxamine did not significantly change !log ODMR! (p > 0.05). The baseline caffeine metabolic ratio (5.1 ± 1.3) decreased only after fluvoxamine (2.8 ± 1.1) treatment (p < 0.05). The extent of inhibition of CYP2D6 and CYP1A2 by paroxetine and fluvoxamine, respectively, correlated with baseline enzyme activity (p < 0.05). 'Conclusion'. Paroxetine and fluvoxamine cause a significant inhibition of CYP2D6 and CYP1A2, respectively, in vivo. The inhibition of CYP2D6 by paroxetine results in an increase in perphenazine plasma concentration and side effects. A reduction of perphenazine dose is recommended during concurrent treatment with paroxetine. These results have potential ramifications for inter-individual variability in the risk for drug-drug interactions mediated by CYP2D6 and CYP1A2.
Constitutive expression of heat shock proteins hsp90, hsc70, hsp70 and hsp60 in the rat during postnatal development

This thesis examines the expression of heat shock proteins hsp90, hsc70, hsp70 and hsp60 in neural and non-neural rat tissues during postnatal development. Western blot analyses showed abundant levels of hsp90 and hsc70 in the brain throughout postnatal development. Levels of hsp60 (which is localized primarily to mitochondria), and cytochrome oxidase, subunit IV (a mitochondrial marker), increased during development, reflecting a developmental elevation in mitochondrial content. In addition, low basal levels of hsp70 were detected throughout postnatal development in certain brain regions. In the developing kidney, hsp90 and hsc70 levels decreased while hsp70, hsp60 and cytochrome oxidase, subunit IV levels increased. Tissue-specific differences in the relative levels of these heat shock proteins were also evident. Hsp90, hsc70, hsp60 and cytochrome oxidase, subunit IV were all localized to neurons in the developing and adult brain by immunocytochemistry.
Kindling-induced changes in neurogenesis in the dentate gyrus of the rat

Dentate granule cell neurogenesis in the rat continues to occur throughout adulthood. Granule cell production is sensitive to a variety of physiological and environmental factors which suggests that the proper regulation of granule cell neurogenesis may be important to the functioning of the hippocampus. This study examined the production of new cells within the dentate gyrus in response to kindled seizures using the mitotic indicator bromodeoxyuridine. An increase in cell production was found to occur within the granule cell layer and molecular layer but not the hilus, when compared to unstimulated control animals. This study shows for the first time that the increased electrical activity of kindled seizures can stimulate the production of new neurons within the dentate gyrus. A possible role for neurogenesis in human temporal lobe epilepsy is discussed.
Ruling relations and representation, the Toronto Star thinspace's depiction of nac, 1983-1997

This thesis is concerned with objectified accounts as a form of knowledge which inform and shape our society. The focus of this work is on news accounts and how these accounts depict NAC, the National Action Committee on the Status of Women, in particular ways. In investigating how depictions of NAC are socially organized in The Toronto Star, the aim of my study is to highlight the processes and practices that enter into the creation and dissemination of these depictions. While these depictions appear to be "objective," they are underpinned by an ideological frame which shapes the account, dovetailing with what Smith (1990) calls an interpretive schemata through which reality is shaped according to the ideological frame. The ideological frame that shapes accounts of NAC in The Toronto Star is that NAC only represents a narrow subset of women which serves to devalue the centrality of NAC as the leader of the women's movement in Canada. The aim of this work is to illustrate the processes and practices that go into producing these accounts that are shaped by this ideological frame. (Abstract shortened by UMI.)
Synthesis and biological activity of conformationally constrained nucleosides and nucleotides

This thesis outlines the synthesis of a variety of conformationally constrained nucleosides and nucleotide analogues. The conformationally "locked" analogues closely resemble specific conformers of natural nucleosides and nucleotides and were used to probe the conformational specificity of particular physiological processes in PC12 cells; nucleoside transport (NT) activity and P$\sb2$-purinoceptor response. 8,2$\sp\prime$-thioanhydroadenosine (3) and the corresponding 5$\sp\prime$-triphosphate derivative are "locked" in the anti-conformation about the glycosidic bond and in the S-type sugar pucker. Both characteristics are known to be highly favoured conformations of adenosine and ATP in solution state, thus it is hypothesised that these endogenous compounds are recognized by NT proteins and P$\sb2$-purinoceptors in these conformations. 8,2$\sp\prime$-thioanhydroadenosine (3) had no effect on NT activity and the triphosphate derivative did not elicit any P$\sb2$-purinoceptor responses. 2,2$\sp\prime$-anhydrouridine (6) and the corresponding 5$\sp\prime$-triphosphate analogue are "locked" in the syn-conformation about the glycosidic bond and in the S-type sugar pucker. Similarly this analogue did not inhibit NT processes, although the 5$\sp\prime$-triphosphate analogue was an agonist for the P$\sb{\rm 2X2}$-purinoceptor. 8-bromoadenosine (1) and 8-mercaptoadenosine (8) represent molecules with modifications on the adenine base moiety; at concentrations of 300 $\mu$M these were found to inhibit the NT mediated uptake of ($\sp3$H) -adenosine by 42 $\pm$ 2 and 58 $\pm$ 2% of control, respectively. Adenosine-2$\sp\prime$,3$\sp\prime$-carbonate (9) adopts a constrained sugar pucker "intermediate" between the S and N-type sugars. This analogue was found to be a potent inhibitor of the NT process (IC$\sb{50} \sim$ 10 $\mu$M).
Study groups in first-year university classes, program development and evaluation

Research was undertaken in Economics 101 offered in the Faculty of Arts, University of Waterloo exploring the feasibility of establishing a study program to respond to the transitional challenges faced by first-year university students. A pilot project was conducted in Fall, 1993, with results indicating the most positive ways the program could be offered to students. In the Fall, 1994, the first-year study group program was offered with the pilot project enhancements incorporated into Economics 101. A total of 86 participants came from two sections of the Economics 101 course. Phase One offered an overview of the characteristics, benefits and recommendations from the study group program; while Phase Two used a case study methodology to examine one study group's meetings over the term. Phase One revealed eighteen groups met at varying times across the term. Size of the groups ranged from 3-5 members. Meetings focused primarily on academic issues including explaining concepts to each other, studying together for midterms, and previewing lecture material for future meetings. Personal discussions centered on ways of adjusting to university life while social conversations focused on topics of interest to university students. Respondents in voluntary telephone interviews said the program was useful in providing academic assistance, support and friendship to students in their first-year. The instructor felt the program offered a way for students to deal with challenges and diversity when beginning their university studies. Recommendations received from all participants--study group members, instructor and non-participants--suggested the program be expanded to other first-year courses. Phase Two analyzed the meeting transcripts from one study group providing detailed information on the content discussed over the term. Based on the analysis, seven topics were discussed over eight meetings. The academic category was the largest, composed of preparation for meetings, content, working together and evaluation topics. The opportunity to work in a group was a positive experience for the members and their personal challenges, fears, expectations and worries were discussed over the term. Cluster analysis provided three indicators--support, cohesion and risk-taking with different types of characteristics noted within each cluster. The process of working together helped students adjust to university in a way they could not have done without each other. Suggestions are provided for Canadian universities to use study group programs to help support students in adjusting to the academic, personal and social transitional challenges within new educational settings.
Flow boiling heat transfer in the quenching of a hot surface under reduced gravity conditions

An experimental set-up, which combined a new state of the art micro-sensor for instantaneous measurements of heat flux and surface temperature, was designed, constructed and used to study the effects of gravity, as well as inlet liquid flow rate and subcooling on rewetting of a hot horizontal surface. The experiments were conducted by injecting liquid R113 and PF5060 into an initially dry, heated channel, which was 40 mm wide, 5 mm high and 200 mm long, on the ground and in reduced gravity aboard the parabolic aircraft, KC-135 and DC-9 of the NASA. The measurements showed large instantaneous fluctuations in heat flux and surface temperature following the onset of rewetting, even after the maximum heat flux was passed, where the heat transfer mode changed from transition boiling to nucleate boiling. Heat flux and surface temperature data showed synchronized responses indicating sufficiently fast response of the sensors and the reliability of the measurements. The boiling curves covering film, transition and nucleate boiling regimes were obtained during quenching and analyzed. The heat transfer characteristics in each boiling mode, as well as rewetting temperature, quench velocity, liquid-solid contact frequency in transition boiling and maximum heat flux were examined in detail for different gravity levels, inlet liquid flow rate and subcooling. The quench velocity and rewetting temperature were found to decrease for R113 but only showed very slight decreases for PF5060 in reduced gravity. A peak in the liquid-solid contact frequency curve was found at wall superheats of 107 ~ 118°C for R113 and 65 ~ 83°C for PF5060 in both gravity conditions. The maximum heat flux for both fluids decreased in reduced gravity except for R113 at high flow rate.
Characteristics of higher education doctoral theses, defrosting some frozen assets

The purpose of this study was to examine characteristics of doctoral theses completed in the Higher Education Group at the Ontario Institute for Studies in Education of the University of Toronto, and to compare specific dissertation properties to corresponding ones from the 'Canadian Journal of Higher Education'. The study was guided by the following three broad questions: (1) What have been the principal characteristics of theses in the Higher Education Group over the past quarter century? (2) What relationships exist between selected characteristics of the theses? (3) How do theses characteristics compare with the corresponding characteristics of the 'Canadian Journal of Higher Education' articles between 1971 and 1995. Content analysis was the methodology employed in this study. Data were collected and then coded from 115 Higher Education Group doctoral dissertations. Selected data from 262 research articles published in the 'Canadian Journal of Higher Education', and from other databases, were also collected and coded appropriately. Tests of reliability and validity were performed on data from the theses and journal articles to ensure accuracy and consistency. The investigation found that roughly an equal number of males and females wrote dissertations, that the majority of authors were pursuing the Ph.D. degree, and that very few graduates disseminated their findings in periodicals or in other media. The most frequent topic areas of research were Administration, Planning, and Management; History and Philosophy; and Professional Education. The data suggest a trend towards more qualitative-type dissertations and a decrease in page-length of theses. As well, the study suggests that specific attributes from theses and the 'Canadian Journal of Higher Education' followed similar patterns of development. Other findings are reported and conclusions are discussed.
Destructive and ultrasonic characterization of adhesive joint durability using open-faced specimens

A major concern in the use of adhesive joints is their durability when exposed to a moist environment. This thesis investigated the durability of two typical commercial adhesives, Permabond E04 and Hysol EA9346, using the peel test and ultrasonic reflection measurements, employing a novel open-faced specimen. The new specimen geometry overcame the drawbacks of the conventional closed adhesive sandwich, resulting in accelerated degradation in a uniform manner. In addition, it facilitated the testing of the joint in a wet (along with the absorbed water) and dry (after drying out the absorbed water) condition. An analytical approach was developed and experimentally verified, to predict the adherend plastic dissipation in the peel test, allowing the determination of the critical fracture energy, <math> <f> G<inf>c</inf></f> </math>, from peel data. The model was used to calculate <math> <f> G<inf>c</inf></f> </math> values for the two adhesive systems as a function of the duration of exposure to water at 67°C. The durability studies showed that for the E04 adhesive, the peeling should be performed in a dry state to assess interfacial weakening, whereas for the EA9346 adhesive, both wet and dry tests revealed interfacial weakening. Failure analysis showed that the degradation for the E04 adhesive was associated with the formation of micro-defects at the interface. Durability of the two adhesive systems was characterized ultrasonically using open-faced specimens. It was found that ultrasound can detect the interfacial degradation of the E04 adhesive, but did not show any significant change in response with degradation of the EA9346 adhesive. Measured values of normal-incidence, longitudinal and shear reflection coefficients were in good agreement with a spring model of the interfacial region for the E04 adhesive, enabling the determination of the spring constants as a function of degradation. An oblique-incidence shear-wave measurement system was developed for the inspection of the interfacial region, and implemented using a novel transducer. An efficient angular spectrum approach was developed to model the oblique measurement system, and the experiments were in good agreement with theory.
Studies of mesoporous inorganic materials

Studies in synthesis and characterization of mesoporous silica have been performed. In particular, four aspects have been studied. Primarily, a new synthetic route to enlarge the porosity of mesoporous silica materials has been developed. The synthetic strategy involves aging the syntheses mixture in the mother liquor and depending on the aging time, a gradual increase in pore sizes is observed from 40 to 65 Å. The growth process involves restructuring of the mesopores under mild aqueous conditions without changing the length of the alkyl chain of the surfactant or addition of auxiliary hydrocarbon molecules. The pore-enlarged products retain the crystal morphology of the starting materials and appreciable solubilization of the structure is not observed during the aging process. Templating behavior of cetylpyridinium chloride in the synthesis of mesoporous silica has also been evaluated. Noticeable improvement in the quality of the resulting product is observed through PXRD, TEM, and adsorption analyses. Synthesis of mesoporous silica is also demonstrated using templating behavior of a mixture of two surfactants: cetylpyridinium chloride (CPCl) and cetyltrimethylammonium chloride (CTACl). As the CPCl:CTACl molar ratio is decreased, a gradual increase in the d100-spacing is observed starting at 'ca'. 41 Å and in sub-angstrom increments reaching to that of 'ca'. 43 Å. A model is presented that simultaneously accounts for the higher degree of structural order of the mesoporous silica templated with CPCl and the ability to fine tune d-spacings on a sub-angstrom length scale using CPCl/CTACl mixtures. In addition, a novel non-aqueous route to formation of lamellar and hexagonal phase of mesoporous silica has been developed. Ethylene glycol is employed as a solvent and as a chelating agent. The chelate effect results in stable glycosilicate(IV) complexes which are necessary for the syntheses and the framework thermal stability of the products has been found to increase via chemical vapor deposition of disilane. This synthetic route has been extended to the synthesis of a novel mesostructured titanium oxide and mixed mesostructured titanium/silicon oxides. The mesoporous mixed titanium/silicon oxides are envisaged to have diverse applications in catalysis, large molecule adsorption and separation science, and the synthetic route developed provides the potential for synthesis of other mesoporous mixed metal oxides over a wide range of compositions.