Half-Sandwich Imido into related complexes of niobium and tantulum - relative of the zirconocene family

This thesis describes studies directed towards the preparation of half- sandwich niobium and tantalirai compounds containing imido and phosphino-carbene ligands, with particular emphasis on the relationship of such species with bent metallocene complexes of the Group 4 triad. Chapter 1 highlights areas of transition metal chemistry of relevance to the general theme of this thesis, including reviews of metal imido and zirconocene chemistry. Chapter 2 describes the use of silylated anilines for convenient solution syntheses of half-sandwich imido complexes of niobium and tantalum of the type Cp'M(N-2,6-(^i)Pr(_2)-C(_6)H(_3))Cl(_2)(Cp' = Cp, Cp*). In addition, the syntheses and reactivities of mono- and bis-alkyl derivatives (methyl, neopentyl, and benzyl) are presented. The bis-neopentyl complexes CpNb(NR)(CH(_2)CMe(_3))(_2) (R = CMe(_3); 2,6-(^i)Pr(_2)-C(_6)H(_3)), reveal multiple a-agostic interactions which have been primarily studied via an X-ray crystal structure determination and NMR spectroscopy. Thermolysis of Cp*Nb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(CH(_2)Ph)(_2) in die presence of PMe(_3) affords die benzylidene complex Cp*Nb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(η(^1)-CHPh)(PMe3) whose X-ray crystal structure has been determined. Chapter 3 describes the preparation of the niobium and tantalum imido complexes Cp'M(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(L)(PMe(_3)) (M = Nb, L = C(_2)H(_4), C(_3)H(_6), CO, Me(_2)C(_2). Ph(_2)C(_2), C(_6)H(_4), PMe(_3); M = Ta, L = C(_2)H(_4), C(_3)H(_6), CO). Single crystal structure determinations on CpNb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(η(^2)-C(_3)H(_6))(PMe(_3)) and CpNb(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(η(_2)-C(_6)H(_4))(PMe(_3)) have been undertaken and their relationship to Group 4 metallocenes noted. Treatment of Cp*Ta(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(L)(PMe(_3)) (L = C(_2)H(_4),C(_3)H(_6)) with a-olefins was found to lead to displacement of PMe(_3) and the generation of tantallacycle containing species. Chapter 4 compares the reactivity of tantalum imido and phosphino-carbenederivatives of the form Cp*Ta(E)(H)(X)(PMe(_3)) (E = N-2,6-(^i)Pr2-C(_6)H(_3), η(^2)-CHPMe(_2); X = H, I) with a number of a-olefins. Investigations into die mechanism of catalytic oligomerisation of a-olefins by Cp*Ta(η(^2)-CHPMe(_2))(H)(_2)(PMe(_3)) reveal that pathways involving metallacycle intermediates are most probable, whereas Cp*Ta(N-2,6-(^i);Pr(_2)-C(_6)H(_3))(H)(_2)(PMe(_3)) reacts with a-olefins to afford stable tantallacycle complexes. The reactivity of die dihydrido species has been moderated by the preparation of mono- iodide derivatives and their reactivity towards a-olefins studied. Cp*Ta(η(^2)-CHPMe(_2))(H)(I)(PMe(_3)) dimerises ediylene selectively to but-1-ene, while Cp*Ta(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(H)(I)(PMe(_3)) reacts with ethylene to form die stable ethyl species Cp*Ta(N-2,6-(^i)Pr(_2)-C(_6)H(_3))(Et)(I). Furtherrmore, studies investigating a variety of niobium and tantalum imido species as possible catalysts for die oligomerisation and polymerisation of a-olefins under industrially relevant conditions have been undertaken in collaboration with B.P. Chemicals Ltd.. Chapter 5 gives experimental details for chapter 2-4

The integration of ProxiMAX randomisation with CIS display for the production of novel peptides

Saturation mutagenesis is a powerful tool in modern protein engineering, which permits key residues within a protein to be targeted in order to potentially enhance specific functionalities. However, the creation of large libraries using conventional saturation mutagenesis with degenerate codons (NNN or NNK/S) has inherent redundancy and consequent disparities in codon representation. Therefore, both chemical (trinucleotide phosphoramidites) and biological methods (sequential, enzymatic single codon additions) of non-degenerate saturation mutagenesis have been developed in order to combat these issues and so improve library quality. Large libraries with multiple saturated positions can be limited by the method used to screen them. Although the traditional screening method of choice, cell-dependent methods, such as phage display, are limited by the need for transformation. A number of cell-free screening methods, such as CIS display, which link the screened phenotype with the encoded genotype, have the capability of screening libraries with up to 1014 members. This thesis describes the further development of ProxiMAX technology to reduce library codon bias and its integration with CIS display to screen the resulting library. Synthetic MAX oligonucleotides are ligated to an acceptor base sequence, amplified, and digested, subsequently adding a randomised codon to the acceptor, which forms an iterative cycle using the digested product of the previous cycle as the base sequence for the next. Initial use of ProxiMAX highlighted areas of the process where changes could be implemented in order to improve the codon representation in the final library. The refined process was used to construct a monomeric anti-NGF peptide library, based on two proprietary dimeric peptides (Isogenica) that bind NGF. The resulting library showed greatly improved codon representation that equated to a theoretical diversity of ~69%. The library was subsequently screened using CIS display and the discovered peptides assessed for NGF-TrkA inhibition by ELISA. Despite binding to TrkA, these peptides showed lower levels of inhibition of the NGF-TrkA interaction than the parental dimeric peptides, highlighting the importance of dimerization for inhibition of NGF-TrkA binding

Development of post- harvest handling technologies for the under-utilised cross-jurisdictional Royal Red Prawn fishery

The Queensland Department of Agriculture and Fisheries led this research project on improving the post-harvest quality of prawns landed from the multi-jurisdictional Royal Red Prawn fishery. The research team have studied the supply chain of Royal Red Prawns including the fishing operations, prawn handling and processing, and current market supply chains. The research team has also undertaken extensive sensory investigation to understand the specific sensory qualities of the Royal Red Prawn to better understand the potential of the species more broadly. The research team determined that the Royal Red Prawn has a clear point of difference to the majority of current commercial species of prawns in Australia, and this point of difference is not being adequately exploited by the current supply chain for the prawn. The research team determined that these unique and distinctive qualities would be worth investigating further towards directing this prawn to the fine dining and food service sector specifically

Management of 'Tough' fish syndrome (TFS) in tropical Saddletail Snapper to re-instill market confidence

A major achievment of this research is the confirmation of fish age being the primary driver of toughness in cooked Saddletail snapper flesh. Knowing the cause provides confidence to develop solutions and make business decisions for the reef fish fisheries . The influence of other fish physiological factors was shown to have little impact with respect to fish flesh toughness. Additionally, there was no apparent connection between flesh toughness and seasonality nor year to year conditions. The possibility of toughness being engendered through in appropriate chilling immediately post capture was ruled out as a factor contributing to tough fish syndrome (TFS). The outcome following on from identification of the cause of TFS surrounded developing procedures for reducing the incidence of tough fish where the cause was preventable . However, as post-harvest handling was not a contributor to toughness, implementing alternative handling procedures was irrelevant. The focus of this outcome shifted to developing strategies to ensure fish at risk of exhibiting TFS did not enter the value chain . This was addressed by provision of currently available technology on non - invasive ultrasonic imaging and near infrared spectroscopy (NIRS) to the industry partners

Agile Data Offloading over Novel Fog Computing Infrastructure for CAVs

Future Connected and Automated Vehicles (CAVs) will be supervised by cloud-based systems overseeing the overall security and orchestrating traffic flows. Such systems rely on data collected from CAVs across the whole city operational area. This paper develops a Fog Computing-based infrastructure for future Intelligent Transportation Systems (ITSs) enabling an agile and reliable off-load of CAV data. Since CAVs are expected to generate large quantities of data, it is not feasible to assume data off-loading to be completed while a CAV is in the proximity of a single Road-Side Unit (RSU). CAVs are expected to be in the range of an RSU only for a limited amount of time, necessitating data reconciliation across different RSUs, if traditional approaches to data off-load were to be used. To this end, this paper proposes an agile Fog Computing infrastructure, which interconnects all the RSUs so that the data reconciliation is solved efficiently as a by-product of deploying the Random Linear Network Coding (RLNC) technique. Our numerical results confirm the feasibility of our solution and show its effectiveness when operated in a large-scale urban testbed.Comment: To appear in IEEE VTC-Spring 201

Emily Weigle’s Letter to Dan Tompkins

This edition is created from the manuscript of Emily Weigle’s letter to Daniel “Dan” Tompkins on March 20th, 1927. This letter is one of number of others that the two wrote back and forth to each another while Weigle lived in Augusta, Georgia, and Tompkins lived in Sylvia, North Carolina. The contents of the letter suggest an on-again, off-again relationship between the two, as Emily is close to Dan, discussing the events of his life at the time, but also states that she is not willing to marry him in his then-current financial state

The Eastman Scholar Mathletes: A Collaborative Partnership

Excerpt: Professional development has been of central importance throughout the mathematics education reforms in our educational history. Recognizing that math teachers represent the major link between the curriculum and student learning, expert practitioners, researchers, and policy makers emphasize professional development as an essential mechanism for deepening teachers’ content knowledge and developing their teaching practices

Pathway Possibilities: The Lilly Endowment's Pathways for Tomorrow Initiative

Looking to the future for what supervision and mentoring will look like and be utilized