Metal-containing polymers (MCPs) are emerging as a class of interesting materials with promising properties and functions. Although many techniques are available for their synthesis, the range of main-chain MCPs available for material applications is limited. Most well-defined main-chain MCP syntheses rely only on the ring-opening polymerization (ROP) of metallocene monomers, thereby new synthetic approaches for novel MCPs are in high demand. In this study a new polymerization technique, migratory insertion polymerization (MIP), was explored and used to produce novel types of MCPs with asymmetric iron repeat-units connected by phosphine-iron (Ph2P-Fe) and iron-acyl (Fe-CO) bonds in the backbone. This research work involved the synthesis, characterization and polymerization of cyclopentadienyl(dicarbonyl)(diphenylphosphinopropyl)iron (FpP). FpP consists of an Fp functional group capable of undergoing a migratory insertion reaction (MIR) and a phosphine group to assist the MIR. FpP was prepared via the reaction between cyclopentadienyl dicarbonyl iron metalate (Fp anion) and (3-chloropropyl)diphenylphosphine, and was characterized using Fourier transform infrared (FTIR), 1H NMR, 31P NMR, 13C NMR, and ultraviolet-visible (UV-Vis) spectroscopies. The molecules undergo intramolecular cyclization reactions at low concentrations in organic solvents, while polymerization occurs in bulk at 70°C, leading to polymers with number-average molecular weights (Mn) up to 12,000 g/mol and narrow molecular weight distributions (PDI=1.08-1.33). These polymers are soluble in a wide range of organic solvents and have a Tg of 100°C.

Thèses (M.A.)--Université de Sherbrooke (Canada), 2001. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Thèses (M.A.)--Université de Sherbrooke (Canada), 2003. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Thèse (Ps.D.)--Université de Sherbrooke (Canada), 2007. / Titre de l'écran-titre (visionné le 21 févr. 2008). In ProQuest dissertations and theses. Publié aussi en version papier.

Universiẗat, Diss., 2000--München.

Colorectal cancer is the second leading cause of cancer-related deaths behind lung cancer in the United States. Colonoscopy is the preferred screening method for detection of diseases like Colorectal Cancer. In the year 2006, American Society for Gastrointestinal Endoscopy (ASGE) and American College of Gastroenterology (ACG) issued guidelines for quality colonoscopy. The guidelines suggest that on average the withdrawal phase during a screening colonoscopy should last a minimum of 6 minutes. My aim is to classify the colonoscopy video into insertion and withdrawal phase. The problem is that currently existing shot detection techniques cannot be applied because colonoscopy is a single camera shot from start to end. An algorithm to detect phase boundary has already been developed by the MIGLAB team. Existing method has acceptable levels of accuracy but the main issue is dependency on MPEG (Moving Pictures Expert Group) 1/2. I implemented exhaustive search for motion estimation to reduce the execution time and improve the accuracy. I took advantages of the C/C++ programming languages with multithreading which helped us get even better performances in terms of execution time. I propose a method for improving the current method of colonoscopy video analysis and also an extension for the same to make it usable for real time videos. The real time version we implemented is capable of handling streams coming directly from the camera in the form of uncompressed bitmap frames. Existing implementation could not be applied to real time scenario because of its dependency on MPEG 1/2. Future direction of this research includes improved motion search and GPU parallel computing techniques.

Transposable elements (TEs) are mobile genetic elements. They are a significant component of many eukaryotic genomes. They are involved in chromosomal rearrangement by serving as substrates for homologous recombination, in creating new genes through a process of TE "domestication", and in modifying and shuffling existing genes by transducing neighboring sequences (Lander et al., 2001). Therefore, both active and inactive TEs are potentially potent agents for genomic change (Kidwell and Lisch, 2001, 2002; Rizzon et al., 2002; Petrov et al., 2003). In the meantime, active TEs are being explored as useful tools for genetic transformation and possible gene drive mechanisms to deliver genes in natural populations (Ashburner et al.,1998; Alphey et al.,2002; Handler and O'Brochta, 2004). My thesis project focuses on AGH1, a novel DNA-mediated TE in Anopheles gambiae and related mosquitoes. I have studied its genomic structure, insertion polymorphism, evolution, and transposition activity. As part of the sequence and structural characterization of AGH1 in the A. gambiae genome, the boundaries of AGH1were determined. The TA target site duplications flanking AGH1 were verified by comparing a genomic sequence that had an AGH1 insertion with the sequence of a corresponding empty site. AGH1 has relatively long, 350bp, TIRs (Terminal inverted repeats). In addition to the transposase ORF (ORF1) that contains a DD34E catalytic motif, it contains an unusual ORF2 with unknown function. Phylogenic analyses clearly suggest that unlike most DD34E transposons that are similar to the Tc1 family, AGH1 belongs to a different clade that is related to the previously characterized fungal TE Ant and protozoan TEC1 and TEC2. Truncated AGH1 and AGH1-related MITE (Miniature inverted-repeat TE) families were also identified. AGH1 insertion polymorphism was studied using 4 natural populations that belong to two molecular forms of A. gambiae, M and S. AGH1 insertions showed considerable differences between M and S forms and the insertions of AGH1 are highly variable in two populations of M. These results are potentially significant in light of the hypothesis that M forms are newly derived incipient species that are only found in West Africa. PCR and sequencing results showed more than 99% sequence identity between AGH1 sequences in A. gambiae, A. arabiensis, and A. melas, which may indicate either purifying selection or recent horizontal transfer. To assess whether AGH1 is currently active, inverse PCR was performed which provided evidence for extrachromosomal circular AGH1 that may be a product of imprecise excision. RT-PCR detected transcripts for both intact and truncated transposase. Preliminary TE display experiments using genomic DNA isolated from different passages of an A. gambiae Sua1B cell line showed possible new insertions and deletions of AGH1 related elements, which may have been mobilized by AGH1. In summary, the structural and genomic characteristics of AGH1 and the phylogenetic relationship between AGH1 and other known transposons in the IS630-Tc1-mariner superfamily have been determined. Significant divergence was shown between M and S forms of A. gambiae according to AGH1 insertion patterns. Observations of high level of insertion polymorphism and low insertion frequency per site in M populations are preliminary indications that AGH1 may be active in some populations. AGH1 has at least been recently transposing and there are also indications for its current activity in A. gambiae cell lines. If AGH1 is indeed active, it has the potential to be used as genetic tools to study mosquito biology and to spread refractory genes into the field populations to help control mosquito-borne diseases. Although a few active DNA transposons have been discovered in different insects and are being used as tools to transform mosquitoes, no DNA active transposons have been reported in mosquitoes. It is our hope that active endogenous DNA transposons may present new features that will help us overcome some of the deficiencies of current transformation tools developed based on exogenous transposons. In addition, the discovery of an active DNA transposon will help us understand how TEs spread in natural populations of mosquitoes, which is critical if we are to use TEs to drive refractory genes into mosquito populations to control vector-borne infectious diseases. The differential insertion patterns of AGH1 in M and S populations are consistent with the hypothesis that the M and S forms of A. gambiae are in the process of incipient speciation. AgH1 showed much higher levels of insertion polymorphisms in two west African populations of the M molecular form compared to two east African S populations. Similarly, the maximum level of chromosomal differentiation is observed in west African dry savannah areas, while a much lower degree of chromosomal polymorphism is observed in east Africa. Therefore our insertion data support the hypothesis that the speciation process is likely to be originated in west Africa, probably as the result of the need of ecological flexibility created by the greater ecological variability of this region. From a biomedical perspective, this type of analysis is critical because the genetic differences between M and S forms may directly impact the effectiveness of mosquito control measure and perhaps disease transmission. / Master of Science

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