Catalytic ethylene oligomerization is a well understood industrially viable process. The large majority of scientific literature and patents concerning this process has been developed with the use of chromium catalysts. Commercial systems producing selective tri/tetramerization, non-selective oligomerization and polymerization are all based on this metal with the exception of a few systems based on other transition metals (Zr, Ti, Ni etc.). This versatility raises interesting questions about chromium’s unique behaviour. Essentially, selective or non-selective oligomerization and polymerization processes could be regarded as belonging to the same category of C-C bond forming reactions, though different mechanisms are involved. The first part of this thesis explores a variety of chromium complexes for ethylene oligomerization purposes. In order to gather further information about the unique behaviour of chromium, we have explored a variety of nitrogen and phosphorus containing ligands. We started with a simple bi-dentate anionic amidophosphine (NP) ligand and assessed the role of the ligand’s negative charge and number of donor atoms in determining the type of catalytic behaviour in relation to the metal oxidation state. This ligand proved capable of generating a series of chromium dimeric, tetrameric or polymeric and even heterobimetallic chromium-aluminate complexes in different valence states. This allowed us to isolate a “single component” self activating Cr(II) complex as well as a rare example of mixed valence Cr(I)/Cr(II) species. Additionally, each of these species acted as switchable catalyst depending on the type of co-catalyst

Cell adhesion is the first step of cell response to materials and the extracellular matrix (ECM), and is essential to all cell behaviours such as cell proliferation, differentiation, migration and apoptosis for anchor-dependent cells. Therefore, studies of cell attachment have important implications to control and study cell behaviours. During many developed techniques for cell attachment, the manipulation of surface chemistry is a very important method to control initial cell attachment. To control cell adhesion on a two-dimensional surface is a simple model to study cell behaviours, and is a fundamental topic for cell biology, tissue engineering, and the development of biosensors. From the engineering point of view, the preparation of a material with controllable surface chemistry can help studies of cell behaviours and help scientists understand how surface features and chemistry influence cell behaviours. During the fabrication, the challenge is to create a surface with heterogeneous surface properties in the micro scale and subsequently to guide cell initial adhesion. In order to control cell adhesion in a spatial and temporal manner, a photochemical method to control surface chemistry was employed to control the surface property for cell adhesion in this project. Two photocleavable derivatives of the nitrobenzyl group were tried on two types of surfaces: a model self-assembled monolayer (SAM) with alkanethiol-gold surface and biodegradable chitosan. Reactive functional groups on two different surfaces can be inactivated by covalent binding with these photocleavable molecules, and light can be further introduced into the system as a stimulus to recover their reactivity. By simply applying a photomask with diffe

A scramjet inlet was designed for use on a small scale, Mach six, ethylene-fuelled vehicle. The inlet used strut-based cantilevered fuel injectors and a well-defined mixing duct to mix fuel prior to the combustor. Designed using theoretical and numerical analyses, the resulting inlet configuration consisted of a single body shock inlet with vertical fuel injector struts and four cantilevered injectors per strut side. This inlet was 80 cm long and 42 cm high. Numerical analysis of the vehicle was conducted with computational fluid dynamics by solving the Favre-Averaged Navier-Stokes equations; turbulence was simulated using the Wilcox k-ω model. Multispecies simulations in two and three dimensions were used to evaluate the design. Analysis of the simulated flow features, thrust potential and mixing efficiency demonstrated favourable vehicle performance. In particular, the inlet allowed for complete combustion when lean equivalence ratios of less than 0.7 were used.

A scramjet inlet was designed for use on a small scale, Mach six, ethylene-fuelled vehicle. The inlet used strut-based cantilevered fuel injectors and a well-defined mixing duct to mix fuel prior to the combustor. Designed using theoretical and numerical analyses, the resulting inlet configuration consisted of a single body shock inlet with vertical fuel injector struts and four cantilevered injectors per strut side. This inlet was 80 cm long and 42 cm high. Numerical analysis of the vehicle was conducted with computational fluid dynamics by solving the Favre-Averaged Navier-Stokes equations; turbulence was simulated using the Wilcox k-ω model. Multispecies simulations in two and three dimensions were used to evaluate the design. Analysis of the simulated flow features, thrust potential and mixing efficiency demonstrated favourable vehicle performance. In particular, the inlet allowed for complete combustion when lean equivalence ratios of less than 0.7 were used.

The synthesis of monodentate biphenyl-amido proligands is reported as well as a series of complexes of lithium with these ligand systems. The solid-state molecular structure of these lithium amides are described as well as their use as synthons in the preparation of amido-arene aluminum complexes. Structural and spectroscopic data suggest that these species exhibit weak arene to metal donation. Attempts to generate aluminum cations from these species are detailed. A new synthetic route to titanium “constrained geometry” precatalysts was utilized to prepare a series of titanium complexes with similar pendant arene groups. The homopolymerization activity of these catalyst systems with ethylene and styrene is detailed. Combination of a sterically encumbered phosphine and large, electrophilic borane was used to effect heterolytic cleavage of disulfides to afford novel thiophosphoniumthioborate salts. A series of exchange reactions demonstrated the facile reversal of this reaction. Similar phosphine-borane systems are found to exhibit divergent reactivity with terminal alkynes, affording either phosphonium-alkynylborate salts from deprotonation or phosphonium-vinyl-borate zwitterions from addition. The scope of Lewis acid, Lewis base and alkyne combinations used to effect similar reactivity is detailed. It was found that the reaction of pyrroles, boranes, and alkynes formed similar addition products that were found to undergo further reactivity to afford C-vinyl pyrroles and nitrogen-boron bicyclic compounds. The synthesis of N-alkyl-bis(pentafluorophenyl)boryl amidinates is presented. The reactivity of these compounds with a variety of small molecules is reported. Reaction with CO2, CO, di-iso-propylcarbodiimide, tert-butyl isocyanide, and benzaldehyde as well as thermally-induced intramolecular rearrangement of these compounds affords a variety of novel nitrogen-boron heterocycles.

Des nouveaux ligands multidentes associant la fonction iminophosphorane (P=N) et des donneurs de types thiolates ou phenolates ont été développés au cours de la thèse. La synthèse de ces ligands présentement plusieurs avantages comme l'utilisation des produits bon marche ou la facilité de monter en échelle. Tous les ligands montrent une grande capacité de se coordiner avec plusieurs métaux, y comprise les métaux de transition, aluminium (group principal) et yttrium (terre-rare). Les complexes résultant de ces coordinations ont été étudiés théoriquement par les calculs DFT et expérimentalement par plusieurs techniques de spectroscopies électromagnétiques (RMN multi-noyaux, diffraction aux rayons X, RPE, UV-Vis, IR). Leur activités catalytiques ont été évaluées en tant que catalyseurs dans l'oligomerisation d'éthylène et la polymérisation de lactide pour des polymères biodégradables. En particulier, la synthèse des plusieurs ligands tétradentes phosphasalens a été mise au point. Ces ligands sont des homologues phosphorés des ligands Salen, qui, eux, ont fait l'objet d'études extensives ces dernières années. Les ligands phosphasalen ont été démontrés d'avoir une grande flexibilité et d'être excellent donneurs d'électrons. Grâce à ces propriétés, ils seront capables de stabiliser des métaux de haut degré d'oxydation. Un premier exemple très encourageant a été fait avec l'étude sur le complexe [Ni(III)-phosphasalen]. Ces ligands phosphasalens s'avèrent également très intéressants en catalyse. En effet, les complexes yttrium de ces ligands sont parmi les meilleurs initiateurs pour la polymérisation de lactide par ouverture de cycles, en terme de performance et stereoselectivity, alors que les complexes salen sont pas ou très peu active pour la même réaction. Ces études pionnières ouvrent plusieurs perspectives pour l'application des ligands phosphasalen en chimie de coordination et catalyse.

The synthesis of monodentate biphenyl-amido proligands is reported as well as a series of complexes of lithium with these ligand systems. The solid-state molecular structure of these lithium amides are described as well as their use as synthons in the preparation of amido-arene aluminum complexes. Structural and spectroscopic data suggest that these species exhibit weak arene to metal donation. Attempts to generate aluminum cations from these species are detailed. A new synthetic route to titanium “constrained geometry” precatalysts was utilized to prepare a series of titanium complexes with similar pendant arene groups. The homopolymerization activity of these catalyst systems with ethylene and styrene is detailed. Combination of a sterically encumbered phosphine and large, electrophilic borane was used to effect heterolytic cleavage of disulfides to afford novel thiophosphoniumthioborate salts. A series of exchange reactions demonstrated the facile reversal of this reaction. Similar phosphine-borane systems are found to exhibit divergent reactivity with terminal alkynes, affording either phosphonium-alkynylborate salts from deprotonation or phosphonium-vinyl-borate zwitterions from addition. The scope of Lewis acid, Lewis base and alkyne combinations used to effect similar reactivity is detailed. It was found that the reaction of pyrroles, boranes, and alkynes formed similar addition products that were found to undergo further reactivity to afford C-vinyl pyrroles and nitrogen-boron bicyclic compounds. The synthesis of N-alkyl-bis(pentafluorophenyl)boryl amidinates is presented. The reactivity of these compounds with a variety of small molecules is reported. Reaction with CO2, CO, di-iso-propylcarbodiimide, tert-butyl isocyanide, and benzaldehyde as well as thermally-induced intramolecular rearrangement of these compounds affords a variety of novel nitrogen-boron heterocycles.

The feasibility of highly dispersed gold nanocatalyst supported on yttria-stabilized zirconia (YSZ) for the model reactions of C2H4 and CO oxidation is demonstrated for the first time. Gold nanoparticles are synthesized on YSZ powder by chemical reduction of the precursor salt in the mixture of ethanol, water and polyvinylpyrrolidone (PVP). Resulting metal loading of the catalysts are 1 wt.% with average particle sizes ranging from 6 to 9 nm. Results of CO and C2H4 oxidation display catalytic activity at 65 0C and 25 0C for CO and C2H4 oxidation, respectively. The catalytic properties of the catalysts are different due to their average particle size. Electrochemical Promotion of Catalysis (EPOC) of C2H4 oxidation is demonstrated. Application of constant potential difference between two electrodes in the bipolar electrochemical cell led to increase in C2H4 conversion. A proposed mechanism explains the bipolar EPOC phenomenon through formation of O2- flux across the electrochemical cell, resulting in the change of Work Function of gold nanoparticles placed in between the electrodes and is electronically isolated.

This thesis develops a novel photopatterning strategy for biomimetic scaffolds that enables spatial and biochemical control of engineered cellular architectures, such as the microvasculature. Intricate tools that allow for the three dimensional (3D) manipulation of biomaterial microenvironments will be critical for organizing cellular behavior, directing tissue formation, and ultimately, developing functional therapeutics to treat patients with critical organ failure. Poly(ethylene glycol) (PEG) based hydrogels, which without modification naturally resist protein adsorption and cellular adhesion, were utilized in combination with a two-photon laser patterning approach to covalently immobilize specific biomolecules in custom-designed, three-dimensional (3D) micropatterns. This technique, known as two-photon laser scanning lithography (TP-LSL), was shown in this thesis to possess the capability to micropattern multiple different biomolecules at modular concentrations into a single hydrogel microenvironment over a broad range of size scales with high 3D resolution. 3D cellular adhesion and migration were then explored in detail using time-lapse confocal microscopy to follow cells as they migrated along micropatterned tracks of various 3D size and composition. Further, in a valuable modification of TP-LSL, images from the endogenous microenvironment were converted into instructions to precisely direct the laser patterning of biomolecules within PEG-based hydrogels. 3D images of endogenous microvasculature from various tissues were directly converted into 3D biomolecule patterns within the hydrogel scaffold with precise pattern fidelity. While tissue engineers have previously demonstrated the formation of vessels through the encapsulation of endothelial cells and pericyte precursor cells within PEG-based hydrogels, the vessel structure had been random, uncoordinated, and therefore, ultimately non-functional. This thesis has utilized image guided TP-LSL to pattern biomolecules into a 3D structure that directs the organization of vessels to mimic that of the endogenous tissue vasculature. TP-LSL now stands as a valuable tool to control the microstructure of engineered cellular architectures, thereby providing a critical step in the development of cellularized scaffolds into functional tissues. Ultimately, this thesis develops new technologies that advance the field of regenerative medicine towards the goal of engineering viable organs to therapeutically treat the 18 patients who die every day waiting on the organ transplant list.

The exact origin of the peculiar naked barley is somewhat illusive. There   is a debate whether it has a single, monophyletic origin or a multiple, paraphyletic origin. It is from previous Asian studies on naked   barley known that a mutation   or a deletion of the nud gene expresses the   naked seed phenotype. Not much   investigation has been done outside of   Asia, least of all in the Nordic countries, on what gives naked   barley its character. Therefore this   study was set up to examine if   the Nordic variant of naked barley shares   the same nud allele as the Asian   and thus has a   close connection with it, or   if they have independent mutations. I   could confirm that the known alleles of the nud gene do determine the seed character of barley. Most of the   results of the PCR genotyping confirmed the phenotype of the tested   accessions, both naked and hulled barleys. However, one visually phenotyped naked   barley cultivar (NGB4580) still amplified with the known primers that would   match the Asian hulled allele, meaning that the Nordic accession NGB4580 of   naked barley did not carry the known nud   deletion. This suggests that naked barley has arisen independently in Asia   and in the Nordic countries.