Combinations of sterically encumbered Lewis acids and Lewis bases are precluded from dative bond formation, failing to yield classical Lewis acid-base adducts. These unique systems are referred to as frustrated Lewis pairs (FLPs) and demonstrate a plethora of unique small molecule activations.Herein, the syntheses of phosphonium alkoxy- and aryloxyborate salts in addition to phosphonium thioborate salts are detailed. The scope of Lewis acid and base, alcohol and thiol, that are effective in this chemistry, is also detailed. The syntheses of novel borate and boronate esters of the form B(OR)3 and (C6R4O2)B(C6F5) are detailed and applied in metal-free heterolytic dihydrogen activation with phosphines. The further study of a variety of perfluoroboranes in the activation of H2 with tertiary phosphines is also detailed. Derivatization of triarylboranes, boronate esters, borinic esters and chloroboranes by reaction with one or two equivalents of alky- or aryldiazomethane is achieved yielding the corresponding RR’C insertion products. The solid-state structures of the free boranes, in addition to Lewis base adducts of a sampling of these species, are detailed. Reactivity of the resulting sterically encumbered boranes in imine hydrogenations, H2 and XeF2 activation are also detailed. Combinations of intermolecular frustrated Lewis pairs are found to react collaboratively to activate greenhouse gases such as carbon dioxide (CO2) and nitrous oxide (N2O), yielding the corresponding zwitterionic compounds R3P(CO2)BR2R’ and R3P(N2O)BR’3. Atom connectivity has been established via X-ray crystallographic studies and molecular structures and parameters are discussed. Subsequent exchange chemistry of both CO2 and N2O species with transition metal and other d-block Lewis acids are investigated and yield zwitterionic compounds and ion pairs which are otherwise unobtainable employing more conventional methods. Transition metal containing Lewis acids are employed in conjunction with tri(tert-butyl)phosphine for the FLP-mediated direct activation of N2O.

No description available.

Within the family of transition metal oxochlorides/bromides containing lone pair elements, the transition metal cations often adopt a low-dimensional arrangement such as 2D layers, 1D chains or 0D clusters. The reduced dimensionality is attributed to the presence of stereochemically active lone pairs which are positioned in the non-bonding orbital and will not participate in bond formation and instead act as structural spacers that help to separate coordination polyhedra around transition metal cations from forming three dimensional networks. On the other hand, the chlorine and bromine ions also play an important role to open up the crystal structure because of their low coordination number. However, fluorine has been rarely used in this concept due to the difficulties in synthesis. This thesis is focused on finding new compounds in the M-L-O-F system (M = transition metal cation, L= p-block lone pair elements such as Te4+, Se4+, or Sb3+) in order to study the structural character of fluorine. Hydrothermal reactions have been adopted instead of conventional chemical transport reactions that are commonly used for synthesizing compounds in the M-L-O-(Cl, Br) family. A total of 8 new transition metal oxofluorides containing lone pair elements have been synthesized and their structures have been determined via single crystal X-ray diffraction. Bond valence sum calculations are used to distinguish in between fluorine and oxygen due to their very similar X-ray scattering factors. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.</p>

The striking similarity between Gestational Diabetes Mellitus (GDM) and Type 2 Diabetes (T2D) in terms of the pathophysiologies and the risk factors has led to the hypothesis that GDM is an early manifestation of T2D, expressed under the stress of pregnancy, and therefore both diseases should share similar susceptibility genes. GDM patients may provide a more homogeneous sample for the genetic causes of the disease than T2D, and therefore make a useful group for the identification of the genes involved. Over 200 GDM affected sib-pairs from 178 families were investigated, with parents available in 40% of cases. Genomic regions from 4 different chromosomes, 6, 8, 14 and 18 were chosen from regions that showed clustering for positive linkage scores in previous linkage studies on T2D and one control region on 13, where no previous positive linkage was reported. A total of 19 microsatellite markers were analysed for linkage to GDM using sib-pair analysis. Subset analyses were performed by ranking sib-pairs on GDM-related variables, e.g. mean BMI of sibs, age at GDM episode, etc. GENEHUNTER was run multiple times, each time including the next highest ranked family in the analysis. This gave a continuous range of scores where increasing or decreasing NPL scores indicated heterogeneity associated with different environmental factors such as age and weight. To evaluate the significance of the subset analyses, the results were compared to 10,000 permutations generated by randomly ranking the sib-pairs. Using the entire dataset, the analysis showed no significant linkage to a disease locus. Positive evidence for linkage was found with the subset analysis on chromosomes 8 and 14, suggesting heterogeneity between sib-pairs in the dataset. Marker D8S1742 on 8p23 showed an NPL score of 3.01 (p=0.001) when age at GDM diagnosis was used as a covariate. Using waist-to-hip ratio (WHR), marker D14S275 on 14q12 showed an NPL score of 2.474 (p=0.006). When adjusted for multiple testing, the results were not statistically significant for linkage to a diabetes disease locus, but gave evidence that GDM and T2D share similar genetic determinants, and defined groups of siblings for follow-up analysis of both types of diabetes.

Orientador: Maria Gorete Carreira Andrade / Banca: Pedro Luiz Queiroz Pergher / Banca: Ermínia de Lourdes Campello Fanti / Resumo: Baseado na teoria de cohomologia de grupos, Andrade e Fanti definiram um invariante algébrico, denotado por E(G;S;M), onde G é um grupo, S é uma família de subgrupos de G de índice finito e Mé um Z 2G-módulo. O objetivo deste trabalho é definir um invariante dual a E(G;S;M), que denotaremos por E (G;S;M), utilizando a homologia de grupos em vez da cohomologia. Com este invariante, obtemos diversos resultados e aplicações, principalmente nas teorias de grupos e pares de dualidade e de decomposição de grupos. Estes resultados fornecem uma maneira alternativa de obter aplicações e propriedades nestas teorias. E, para desenvolver este trabalho, estudamos as teorias de (co)homologia absoluta e relativa de grupos, bem como suas interpretações topológicas, e a teoria de grupos e pares de dualidade / Abstract: Based on the cohomology theory of groups, Andrade and Fanti defined an algebraic invariant, denoted by E(G;S;M), where G is a group, S is a family of subgroups of G with nite index and M is a Z 2G-module. The purpose of this work is to define a dual invariant of E(G;S;M), which we denote by E (G;S;M), using the homology of groups instead of cohomology. With this invariant, we obtain many results and applications, especially in the duality and splitting theories of groups. These results provide an alternative way to get applications and properties in these theories. And to develop this work, we studied the absolute and relative (co)homology theories of groups, as well as their topological interpretations, and the theories of duality groups and pairs / Mestre

This thesis deals with generalized fibre spaces. It improves upon existing definitions and introduces new ones. It establishes the category of pairs and the category of g.f.s. The relationship between classical fibre spaces and generalized fibre spaces is examined. The induced g.f.s. is defined as well as the concept of section and it is established that the lifting of a fully regular continuous g-function is equivalent to the existence of a section in the induced g.f.s. Finally the lifting theorem for g.f.s. is stated and proved. / Thesis / Doctor of Philosophy (PhD)

No description available.

rhe non-copulatory estrous behaviour of semi-free ranging female Japanese monkeys was observed for 3 months, in order to investigate the role of the female in the establishment of mating pairs. It was concluded that the females play a very active role in the formation of mating pairs, showing three times more solicitation behaviour than males. They also reject more than 30% of the advances they do receive. This is interpretated as an indication of selectivity in the choice of sexual partners. The behaviour of the female in this courtship context is described, with emphasis on preceptive or solicitation behaviour. The data were tested for behavioural differences based on the female's age, rank, parity, number of offspring and the presence of an infant, and for differences based on the age, rank and spatial status of the interacting male. Age of the female had the greatest effect on behaviour, with older females behaving in a more calm, sophisticated manner when soliciting a male. Age was also the most significant male variable, with females showing more rejection to younger males. Other than age related findings it must be concluded that these sociological characteristics of the animals are not predictive of the females' courtship behaviour. A number of alternate lines of inquiry for future research are suggested. They include an investigation of the hormonal basis of estrous behaviour, a multivariate analysis, and a sequential analysis of behaviour. / Thesis / Master of Arts (MA)

Heavy metals from natural and man-made sources can be a great threat to human and animal life. As small inorganic ions they are challenging to detect, usually requiring expensive and complicated machinery. Several heavy metals can accumulate in the human body, leading to long term toxic effects on the nervous system. Many bacteria have developed strategies to survive in heavy metal rich environments. One of these strategies is a bacterial operon containing genes for detoxification mechanisms controlled by a promoter and a regulatory protein. In this work some of these promoter-protein pairs, Pars-ArsR, PcopA-CueR, PmerTPAD-MerR and PzntA-ZntR from Escherichia coli have been employed in the design and construction of a set of biosensors aimed at the detection of heavy metals in drinking water. Biosensors usually employ biological recognition elements, transducing the signal from these to produce an output that can be integrated into electronic circuitry. The sensors presented in this work focus on reducing complexity and on providing a controlled sensor reaction. The arsenic biosensor ‘AsGard’ is based on the Pars-ArsR pair and functions by making the dissociation of an ArsR-mCherry fusion protein from its binding site in the Pars promoter visible. In the cell, ArsR dissociates from Pars upon binding of trivalent arsenic ions. Immobilising the relevant part of the Pars sequence on a solid plastic support allows for the mobilisation of previously bound ArsR-mCherry proteins in the presence of arsenic to become the sensor output. The AsGard sensor detects arsenic within minutes in a concentration range overlapping with the arsenic thresholds for drinking water as set by the World Health Organisation. Additional prototype sensors are presented bringing a reporter gene under the control of the aforementioned promoters. These sensors have been tested in vivo and in vitro in a cell free transcription translation system and partially detect metal concentrations close to relevant ranges. The Pars based sensor is tuneable in vitro by modifying the ratio of the supplied regulatory protein ArsR and is able to detect arsenic well within the relevant range. Spinach2, a fluorescent RNA aptamer, may make future designs independent from translation, drastically reducing complexity of cell free biosensors based on cis-trans transcriptional regulation.

In an unpublished study in Toronto it was observed that cases were in Hardy-Weinberg Equilibrium at a locus whereas their family members were in Hardy-Weinberg Disequilibrium (HWD). This led to an investigation of relatives of affected individuals to see whether the multiplicative model could be revealed by a nonzero HWD coefficient in relatives. Genotypic frequencies and HWD coefficients were derived for affected individuals and their affected and unaffected relatives. Methods were also developed to test for association using data from affected individuals and their relatives. In addition, a model was developed to assess whether the HWD observed in a data set from a stratified population can be explained by both genetic association and stratification. Parameter estimates for these models can be obtained using maximum likelihood methods, and used to deduce the mode of inheritance of the disease. / Departure from HWE (HWD) in a sample may indicate genotyping error, population stratification, selection bias, or some combination thereof. Therefore, loci exhibiting HWD are often excluded from association studies. However, it has been shown that in case-control studies HWD can result from a genetic effect at the locus, and HWD at a marker locus can be interpreted as evidence for association with a disease. In an unpublished study in Toronto it was observed that cases were in Hardy- Weinberg equilibrium at a locus whereas their family members were in HWD. It has been shown that the HWD coefficient for a multiplicative genetic model is zero. This led to an investigation of relatives of affected individuals to see whether the multiplicative model could be revealed by a nonzero HWD coefficient in relatives. Genotypic frequencies and HWD coefficients were derived for affected individuals and their affected and unaffected relatives. A substantial HWD was found in both individuals in dominant and recessive genetic models but HWD is only slightly nonzero for additive and multiplicative models. Methods were also developed to test for association using data from affected individuals and their relatives. Parameter estimates for these models can be obtained using maximum likelihood methods, and estimates provide valuable information regarding the mode of inheritance of the disease. The methods were applied to 112 discordant sib pairs with Alzheimer’s disease typed for the ApoE polymorphism and a significant association was observed between the "4 ApoE allele and Alzheimer’s disease. Case-control studies may indicate spurious association with a marker locus in a stratified population. Methods were developed to determine if the HWD observed in a data set from a stratified population can be explained by both genetic association and stratification. Parameter estimates for these models can be obtained using maximum likelihood methods, and used to deduce the mode of inheritance of the disease. Applying the model to the R990G SNP of the CASR gene, it was found that the HWD was adequately explained by a recessive genetic association and a stratification proportion of 10%, consistent with the population of Toronto.