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This thesis describes studies directed towards the preparation of bis (imido) complexes of the Group 6 metals containing olefin, phosphine, acetylene, and alkyl ligands with particular emphasis on their relationship with Group 4 bent metallocenes. The polymerisation mechanism of the Phillips catalyst (CrO(_3)/SiO(_2)) is examined using XPS (X-Ray Photoelectron Spectroscopy) and in situ mass spectroscopy. Chapter 1 highlights properties of some of the important ligand classes that are used throughout the remainder of this thesis. Chapter 2 describes a high yield one-pot synthesis of molybdenum bis (imido) complexes of the type Mo(NR')(NR")Cl(_2).DME. In addition a number of attempts to extend this strategy to other metals are described, including a novel synthesis of the chromium complex [Cr(_2)Cl(_9)] [NHEt(_3)](_3). Chapter 3 describes the synthesis, characterisation, and reactivity of the bis (imido) bis (phosphine) complexes Mo(NAr)(_2)(PMe(_3))(_2) and [Mo(N(^t)Bu)(µ-N(^t)Bu)(PMe(_3))](_2). Further studies on bis (imido) olefin complexes of the type Mo(NAr)(_2)(PMe(_3))2(η(^2)-C(_2)H (_2)) and Mo(N(^t)Bu)(_2)(PMe(_3))(η(^2)-C(_2)H(_4)) was undertaken and concentrated on their structural relationship to Group 4 metallocene species. Chapter 4 describes the preparation, structure, and reactivity of some bis (imido) acetylene complexes Mo(NR)(_2)(PMe(_3)) (PhC=CR’) (R= Ar, (^t)Bu; R'= Ph, H). Preparation of bis (imido) alkyls was undertaken in attempts to generate benzyne and alkylidene derivatives. Chapter 5 studies the Phillips polymerisation catalyst using XPS and mass spectroscopy. Model systems were used to probe reactive surface species their use reveals a number of features that are difficult to observe with the actual catalyst. Aspects of molecular chemistry have been examined which are believed to relate directly to the heterogeneous system allowing a possible polymerisation mechanism to be postulated. Chapter 6 gives experimental details for Chapters 2-5. Philip William Dyer (November 1993)

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Residual stress distributions in injection moulded polystyrene plaques have been computed using various calculation methods based on procedures from the literature. Some of the mathematical procedures have been extended to provide improved analysis of the process. The results have been compared with measured distributions obtained using the layer removal technique. The purpose of this work was to resolve some of the disagreements between the measured residual stress distributions in injection moulded parts and those predicted by computations made in the literature. The calculations are made using the general purpose software "Mathcad". Various temperature, time and pressure dependent material models have been used to calculate the residual stress and they are compared. Special attention has been paid to choosing boundary conditions that match the moulding parameters used in the manufacture of the injection mouldings on which the measurements were made. Similarly, care has been taken to choose boundary conditions that correspond with the different actual storage times before analysis for the samples and also boundary conditions that correspond with the post-moulding conditioning. Measurements of residual stresses distributions were made on mouldings produced under conditions chosen to simplify the modelling requirements. The sensitivity of the calculations to the materials property data and to the boundary conditions used have been examined. The experimental verification includes examination of the postmoulding changes. The predicted residual stress distributions over the entire moulding and post-moulding history have been found to be in generally good agreement with the corresponding experimental results under various processing conditions and post-moulding changes. In particular, kinematic boundary conditions for the moulding conditions and the postmoulding conditions, due to different temperaturesa nd relaxation times of the polymer, have been found to be critical ingredients in the calculation of the residual stress distributions.

The purpose of this study was to explore how Dual Credit (DC) programs at Ontario high schools impacted the persistence of students when they are in college and what specific features of these programs affected the participating students’ academic performance. This study focused on the Dual Credit students enrolled full-time at Sir Sandford Fleming College who successfully completed one full-time semester of academic study. Fleming College is one of the 24 Ontario Colleges of Applied Arts & Technology. This was a case study based on both qualitative and quantitative data collected by a number of methods including survey questionnaires, audio-recorded phone and face-to-face interviews, and document analysis. There were a number of findings related to persistence at College. For example, the DC student group persisted at the same rate as did all College students and DC students who enrolled in a College program that was “related” to their DC program were more likely to persist at college. Although there was no attempt to compare the data for the two groups because of uncontrollable variables, this study found that DC students (as a group) did not achieve academically quite at the same level, as did all Fleming College students. However, considering that the DC target group was “at risk” students, the overall academic achievement (64%) of the DC students (2011) was similar to the academic achievement of all College students (68%). The participants in this study recommended that the DC program be as much like college as possible. This study supports previous research, which indicates that the DC courses should be delivered at the college campus (rather than in the high school) and DC students should be integrated with other college students. Although this was a case study of DC students at only one Ontario College and the findings are not generalizable to other sites, the findings of this study will partially address a gap in the research literature and add to the body of knowledge about the impact of DC programs in the areas of student engagement, integration and persistence with respect to DC programs elsewhere.

The purpose of this study was to explore how Dual Credit (DC) programs at Ontario high schools impacted the persistence of students when they are in college and what specific features of these programs affected the participating students’ academic performance. This study focused on the Dual Credit students enrolled full-time at Sir Sandford Fleming College who successfully completed one full-time semester of academic study. Fleming College is one of the 24 Ontario Colleges of Applied Arts & Technology. This was a case study based on both qualitative and quantitative data collected by a number of methods including survey questionnaires, audio-recorded phone and face-to-face interviews, and document analysis. There were a number of findings related to persistence at College. For example, the DC student group persisted at the same rate as did all College students and DC students who enrolled in a College program that was “related” to their DC program were more likely to persist at college. Although there was no attempt to compare the data for the two groups because of uncontrollable variables, this study found that DC students (as a group) did not achieve academically quite at the same level, as did all Fleming College students. However, considering that the DC target group was “at risk” students, the overall academic achievement (64%) of the DC students (2011) was similar to the academic achievement of all College students (68%). The participants in this study recommended that the DC program be as much like college as possible. This study supports previous research, which indicates that the DC courses should be delivered at the college campus (rather than in the high school) and DC students should be integrated with other college students. Although this was a case study of DC students at only one Ontario College and the findings are not generalizable to other sites, the findings of this study will partially address a gap in the research literature and add to the body of knowledge about the impact of DC programs in the areas of student engagement, integration and persistence with respect to DC programs elsewhere.

This study modeled trajectories of four psychosocial competencies (autonomy, industry, identity, and intimacy) across four years of university and year-to-year covariation of these competencies with typical student experiences (living away from parents, academic performance, dating, and alcohol use) in 195 Canadian students. Analyses revealed that, on average, autonomy and identity did not change over time. Accounting for gender differences, however, revealed some linear changes across time for these competencies. Industry and intimacy showed curvilinear trajectories of change. Year-to-year, students reported higher autonomy and identity when living away from their parents and when getting higher grades. They also reported higher industry when getting higher grades. When students dated they reported higher identity and intimacy; dating women also reported higher autonomy than dating men. When dating students reported higher intimacy they reported higher perceived affection within their romantic relationships. Possible mechanisms for the observed patterns and their implications are discussed.

This critical ethnographic study explores couples experiences of spousal support during the transition to first-time parenthood and the organization of paid and family work. How first-time parents manage paid and family work is central to the experience of support and critical to an ongoing nurturing relationship. Seven couples were selected from the principal study, Mobilizing Intergenerational Social Support during the Transition to Parenthood, and were interviewed prior to the birth and again when infants were nine months to one year of age. On the whole, first-time parents reported positive support experiences with their spouses. Nonsupport occurred most often when parents were required to manage the interface between family work and paid or student work. The exchange of support between first-time parents may be strengthened by offering flexible work options and enhanced access to and provisions in parental leave policies. Prenatal education highlighting the common concerns of first-time parents may further strengthen support.

Transition dairy cows are vulnerable to negative consequences of depressed feed intake due to a transient state of negative energy balance that predisposes them to disease after calving. Competition has been identified as one factor that can decrease feeding activity in mid-lactation cows, but the effects of competition on the transition cow are less well understood. The objective of this study was to test the effect of a competition on the behaviour and feed intake of transition cows. Standing behaviour, feeding behaviour and dry matter intake (DMI) was monitored from 1 wk before to 2 wk after calving for 110 Holstein dairy cows. Social behaviour was recorded in the week before calving. Cows were assigned to a competitive (2:1 cows:bin) or non-competitive (1:1 cow:bin) treatment at the start of the study. Treatment groups were balanced for parity and baseline feeding data, resulting in 8 primiparous and 10 multiparous cows per treatment. Competition dramatically increased the number of agonistic behaviours between cows at the feeder. Primiparous cows showed no change in either feeding or standing behaviour when fed in a competitive environment; however, they increased their total meal duration and within-meal intervals in the wk -1 before and wk +1 after calving. In wk -1 before calving, competitively fed multiparous cows increased the frequency of visits to the feeder but consumed less feed at each visit, resulting in decreased daily DMI. Throughout the experiment, multiparous cows fed competitively spent less time eating at each visit and ate at a faster rate, particularly during the 2 wk after calving. Multiparous cows on the competitive treatment also increased the time they spent standing (without eating) compared to cows on the non-competitive treatment. Feeding rate was negatively correlated with social status in multiparous cows. In summary, the results of this study indicate that restricting access to the feeder increases agonistic behaviours regardless of parity, and cows of different parity and social status respond differently in terms of feeding and standing behaviour.