title: A second best voyage: Judaism and Jesus on oaths and vows

contributor:
Meyer, B. F.
Religion

subject: Religion Religion

abstract: The language of oaths and vows--reserved in the Bible for extraordinary situations--by the end of the Second Temple period had become the language of the marketplace. Carelessness in swearing oaths and taking vows regularly led to swift regret. Religious leaders within Judaism accordingly found themselves confronted with two questions: Which oath and vow-formulae were binding? And how did one gain release from an oath or vow? A number of persons and groups within Judaism offered solutions to these problems: Philo, the Dead Sea Covenanters, the Pharisees, and Jesus, whose solution was the most radical of all. The thesis examines all these answers, sets all of them in context, and relates them to one another. It is particularly concerned to relate the answer of Jesus to those of his contemporaries. The peculiarly Jewish bent of the question of oaths has led some to doubt the authenticity of Jesus' prohibition. That is, the discussion in Matt 5:33-37 may have entered the tradition, not from Jesus, but directly from Judaism. Here, however, it is important to identify the occasion of Jesus' prohibition, to locate it in the context of Jesus' concern for sins of the tongue, the sanctification of God's name, and the radical demands of the Kingdom of God. A series of observations relevant to historicity, including a look at such comparable pericopes as Matt 23:16-22 and Mark 7:11, vindicates the prohibition of Jesus as probably historical. A new question arises, however, respecting the history of this tradition within the Matthean redaction. Did Matthew modify or deflect the thrust of Jesus' word? The critical probabilities favour a negative answer. Matthew at this point was probably Jesus' best interpreter. The dissertation proposes and defends the independent integrity of the stands on oaths and vows adopted by Philo, Qumran, and the Pharisees. It is their concern for the proper use of oaths that invites comparison with Jesus. The contrast between the answer of Jesus and other Jewish responses to the issue of oaths and vows is irreducible to the time-honoured distinctions between principle and casuistry, transparency and hypocrisy. Rather, the key question bears on whether the Hebrew Bible is the definitive authority. Jesus, with his distinctive vision of the Kingdom of God and its demands, disregards some of the problems with which others contend and claims an authority that transcends that of Moses: the will of God.

abstract: Doctor of Philosophy (PhD)


title: A study of α/β boundaries in a Zr-2.5 wt % Nb alloy

contributor:
Purdy, G.R.
Materials Science and Engineering

subject:
Materials Science and Engineering
Materials Science and Engineering

abstract: The crystallography and the interfacial structure of interphase boundaries in a Zr-2.5 wt% Nb alloy have been studied by transmission electron microscopy (TEM), and the results compared with the predictions of a model developed in this work. The α phase (HCP), when precipitated from β (BCC), usually forms as intragranular plates. The habit plane of an α plate is characterized by the regularly spaced dislocations, parallel to the long axis of the α plate. These dislocations, about 10nm apart, have a Burgers vector [0 1 0] with respect to β phase. The orientation relationship between α and β phases was found to deviate slightly from the ideal Burgers orientation relationship. Based on the O-lattice and invariant line analysis a geometrical model has been further developed. The cell structure of O-lattice, which is the key information in predicting the configuration of the interfacial dislocations, has been constructed by a simple calculation made in reciprocal space of the O-lattice. This is expected to improve the general application of the existing O-lattice model. The plane of the least lattice mismatch, determined by the O-lattice plane of the smallest spacing, is consistent with the observed habit plane. The optimum orientation relationship suggested based on the analysis of mismatch in the habit plane is shown to deviate slightly from the Burgers orientation, which is supported by experimental evidence. The analysis also indicated that the misfit in the habit plane could be accommodated completely by a set of to [0 1 0]ᵦ dislocations of ~10nm in spacing, lying along the invariant line, in agreement with the experimental observations.

abstract: Doctor of Philosophy (PhD)


title: The Dynamics of a Barrier Island Chain, Prince Edward Island, Canada

contributor:
McCann, S. B.
Geography

subject: Geography Geography

abstract:
The Malpeque barrier chain is a 43 km long sandy barrier shoreline, consisting of three islands and a spit at the present time. This shoreline has limited fetch distances to the north, northeast, and east, and storm waves dominate the coastal environment in the 8 to 10 month period of ice-free conditions. Longshore sediment transport is to the southeast for the exposed eastern section of the field area, at rates generally between 160,000 and 250,000 m³ yr⁻¹, but transport rates are lower in the sheltered northwestern section. The longshore sediment transport rates are comparable with moderate rates for open ocean coasts.

The age of the barrier shoreline is between 1,500 and 3,000 years. The oldest section of shore, Hog Island in the east, incorporates a progradational series of ridgos formed earlier than 1765, which possibly relates to the initiation of the barrier island chain. This western section of coast is a transgressive barrier shore, owing much of its present form to coastal actions in the last 200 years. The barrier islands occur as a shallow sediment body over bedrock, and are generally less than 15 m thick in the duno area, thinning seawards to the outcrop of bedrock at depths between 9 and 17 m.

The occurrence of numerous temporary inlets within the last 200 years has resulted in 12.5 km of the present barrier island chain's morphology being affected by actions associated with inlet development and closure. The temporary inlets provide the setting for much of the landward movement of sediments within the island system. Over 90% of the sand moving landwards in the 1935-68 period in the Malpeque barrier chain occurred at contemporary and former inlet locations. Inlets appear to be more important in this regard than on transgressive barriers along some ocean coasts, where widespread overwash and wind action are also significant in moving sand landwards.

The restricted nature of overwash results in the common occurrence at narrow barrier island sections, less than 200 m in width. The combination of closed inlets, washover passages, and narrow sections gives rise to the unusual highly irregular lagoon margin characteristic of the transgressivity barrier shore here.

The average shoreline erosion rate for the 1935-68 period is low - 0.26 m yr⁻¹. Erosion was discontinuous in location along the shore in that period and in the 200 year period, occurring mainly in the lower energy western half of the field area and along eastermost Hog Island. The bread alongshore variations in the occurrence of erosion imply sediment deficits in the littoral zone of the eroding sectors: the irregular discontinuous nature of the shoreline retreat in those locations over years to decades indicates the marginal mature of the deficits. Shoreline erosion in the eroding sectors appears to result from the short-lived formation of 400-600 m lengths of narrow foreshore, causing accelerated erosion under storms encountered each winter.

Shoreline erosion at Malpeque is a result of the limited sand reserves in the nearshore and on the shoreface, in relation to the energy levels of the coastal processes moving sand seawards and alongshore. Sea-level rise is not the primary cause of shoreline retreat on this shore; evidence also suggests that sea-level rise is not significant on barrier coasts elsewhere.

\,~ut, ,nd l4tormwtw\'l!I dl~n\tl\nt" tl(\~ ('oat'\~Al,~nvtl'onml'nt il\'~lW a tl.'·lO u\Qu.th ('dod I.'f tC(\"'f~l't' ,,(\nd t ~tN'N. 1,~~nf'\~hol'~' I,itl"\HIMl\t tt"nn[~p\l1.·t bt t\.) th0 I outhet'\8t for th,'I ~xposyd "'l\!it,\rn tltl'Ct lon,or thl~ fh'lh\ l\f\"l.l. ftt r{\tllf\ I (\n,\r«l1y b('t"''''''N\ lb0000 n~\d r~o,ooo m) yr-t • but trftuf'l'\wt ,~fttl\!i nt'" OW0r in th0 ·8ht.'ltl.~rJd northw"'l.i\tl'l"U (4\"ction. 'Ihl\ r'ongt"lt\,'\n' tl0d'l\ynt < ... ' rnl\t\port rat(>t' nr~ ~omlH\t'Ab)l' ....1th mNh'rnu' t'~t~~f\ for (.l\Wn o~"t\ C\)(\8tf'. Tbo"&\Stl of thll bnrri,'r 8ho1'l'll1\('1 16 h..'twNm \t~OO ~\ld 3.0ll0 '-'arN. Th('l oldNlt ~l\ction of flbon't UOR ll\~l\t\d in th\' ""at tincot\po.t'&\t\.'l\ . I ' . .. pr"l\rndat io••l .ortao 0 f rids". forUled o.r11or tim. 17C~' whie11 I possibly rcl'l.lte9to the initiation of thl' barrier island ch.:lin. Th~\ . ! !o ~et"t~rn l"(let!on of COl.lftt iN n trft1\~Brl'lf\t\lv\.l \larril'lr flhon\, owing Illl,cb ~f ito presont form to cont'\tnl action6 in the Ift~t 20B y~ar~. Th~ . I barrior i81~~d8 occur as a shallow sedimQnt body.over bl'drock; and ar~ , . 1.U

abstract: Doctor of Philosophy (PhD)


title: Synthesis of β-lactam-4-ylidenes and their application as synthons for novel β-lactam synthetic methodologies

contributor:
Warkentin, John
Chemistry

subject: Chemistry Chemistry

abstract: The first portion of this thesis deals with the chemistry of the imino-triazoline, imino-thiadiazoline, and imino-oxadiazoline systems. All three systems have the cyclic cis azo function as a common feature, but it was found that each system has its own characteristic chemistry. Upon quaternization of the sp² ring carbon the stability of the resulting cyclic azo compounds increased in the following order: triazolines < thiadiazolines < oxadiazolines. Thus, the reaction of the imino-triazoline with benzoylcyanide formed the aziridine. Moreover, the imino-triazoline system did not form a stable spiro-β-lactam triazoline when treated with diphenylketene. On the other hand, the quaternization of the imino-thiadiazoline sp² ring carbon did not always lead to N₂ extrusion. The reaction of the imino-thiadiazoline with diphenylketene led to N₂ extrusion followed by electrocyclic ring closure to form the spiro-β-lactam thiirane as the only product, if the substituent on nitrogen was a phenyl group. Replacing the phenyl group on nitrogen by a benzyl group led to the isolation of both the spiro-β-lactam thiadiazoline and the product of N₂ extrusion, the corresponding spiro-β-lactam thiirane. The spiro-β-lactam thiadiazoline loses N₂ thermally to form the thiirane as the only product. The chemistry of the oxadiazoline system was very different. Imino-oxadiazolines reacted with different substituted ketenes to form the corresponding spiro-β-lactam oxadiazolines. Quaternization of the sp² ring carbon did not lead to N₂ extrusion; the spiro-β-lactam oxadiazoline system (172) was very stable at room temperature. The thermolysis of the spiro-β-lactam oxadiazoline system (172) at 100°C gave products derived from the novel β-lactam-4-ylidene (181), as an intermediate. Product analysis implied the generation of the carbene 181 quantitatively. [Image Removed] The second portion of this thesis deals with a study on the scope of the spiro-β-lactam oxadiazoline system (172), as a source for β-lactam-4-ylidenes (181). This oxadiazoline system (172) proved to be an excellent source for the β-lactam-4-ylidene (181), in the sense that it is a mild, bottleable, and a quantitative source. On the other hand, the chemistry and scope of the novel β-lactam-4-ylidene (181) were studied. The β-lactam-4-ylidenes (181) were trapped inter- and intra-molecularly by insertion and addition reactions. Carbene trapping experiments were carried out to form the novel spiro-β-lactam cyclopropenes, spiro-β-lactam cyclopropanes, various carbene insertion products and fused bicyclic β-lactams. Thus, the β-lactam-4-ylidene (181) proved to be an excellent synthon for novel β-lactam systems that could not be synthesized, in a single step, otherwise.

abstract: Doctor of Philosophy (PhD)


title: An empirical study of round and block norms for modelling actual distances

contributor:
Love, R.F.
Management Science/Systems

subject: Management Information Systems

subject: Management Sciences and Quantitative Methods

subject: Management Information Systems

abstract: In this dissertation, we look at two families of distance predicting functions, the ℓkpθ norm family and the block norm family, that can be used for modelling actual distances. To compare the distance-predicting accuracy of the two families, an empirical study is conducted. Two types of regions, which are large geographic regions and urban centres, are used in the study. In the large geographic regions, actual distances between cities in each region are modelled, whereas in the urban centres, actual distances within a city are modelled. To evaluate the accuracy of the different norms, two goodness-of-fit criteria are employed. For the block norms, new procedures that determine global solutions for the criteria are developed. Normality assumptions regarding the individual terms of the criteria are examined since these terms are used to formulate statistical tests that are sensitive to departures from normality. A new criterion for evaluating the accuracy of a distance predicting function is developed. This criterion, unlike the other two criteria, is impartial both to short actual distances and to long actual distances. The criterion is used to evaluate the accuracy of the ℓkpθ norm for the geographic regions that were used in the empirical study. A statistical analysis of the errors from this new criterion leads to the development of confidence intervals for unknown distances in any geographic region. The results from this thesis will help an analyst select an appropriate distance predicting function to model actual distances in any application. Further, a new measure for evaluating distance predicting functions may be considered by an analyst, and confidence intervals for unknown distances can be easily constructed.

abstract: Doctor of Philosophy (PhD)


title: Construction and characterization of E1B mutants of adenovirus type 12

contributor:
Mak, Stanley
Branton, Philip E.
Biology

subject: Biology Biology

abstract: Early region 1 (E1) of the adenovirus (Ad) genome contains two overlapping transcription units, E1A and E1B, which encode proteins essential for productive viral infection of permissive human cells and for transformation of nonpermissive rodent cells. E1B of Ad12 produces two major proteins of 482 and 163 amino acid residues. termed 482R and 163R (495R and 175R in Ad2, or 496R and 176R in Ad5). Studies with a variety of mutants affecting the 175R, 176R or 163R proteins have indicated that this product is multifunctional and involved in the protection from degradation of viral and cellular DNA and in the determination of the cytopathic phenotype of infected cells. In addition it is required for complete and efficient transformation of cells. However, a recent report in which the mutants with no initiation codon for 163R or with a downstream stop codon in the 163R coding region were found to be capable of transforming primary baby rat kidney cells has seriously questioned the transformation function of 163R. The functions of the E1B 482R protein in Ad12 have also been characterized. This protein is involved in cellular transformation and is required for accumulation of viral late mRNA and proteins while blocking the same processes for cellular mRNAs and proteins. It is also required for tumour induction and plays some role in viral DNA synthesis. To examine the role of the Ad12 E1B 163R protein more thoroughly, in particular to determine the transforming function of the protein, deletion and point mutations were introduced at various positions in the coding sequence of 163R by oligonucleotide-directed mutagenesis, including a mutant that lacks the 163R AUG initiation codon. The results indicated that many of these mutants yielded unstable 163R-related products induced DNA degradation and enhanced cytopathic effect (cyt/deg phenotype) in infected KB cells, and transformed primary rodent cells at efficiencies significantly lower than wild-type Ad12. Deletion of the final 16 residues at the carboxy terminus did not affect the phenotypes. Alteration of residue 105 reduced transforming efficiency significantly, suggesting that this region of 163R is functionally import. Removal of the initiation codon at nucleotide 1541 blocked production of 163R but resulted in a large increase in the synthesis of the E1B 482R protein and a transforming efficiency similar to that of wild-type Ad12. These results suggested that 163R plays a role in transformation but that normal transforming efficiencies can be obtained in its absence if a sufficient quantity of 482R is produced. To define the functional role of Ad12 E1B 163R and 482R in viral gene expression, viral mRNA accumulation from infected cells was assessed by Northern blot analysis. The results demonstrated that the E1B 163R protein does not play a crucial role in modulating viral gene expression. However, a 482R mutant lacking residues 114-155 produced greatly reduced levels of both early (E2B and E4) mRNA and late protein and was defective for viral DNA replication. These results indicated that the 482R protein plays a role in viral early mRNA metabolism resulting in secondary effects on viral DNA replication and viral late protein synthesis.

abstract: Doctor of Philosophy (PhD)


title: Electrochemical Determination of the Standard Free Energy of Formation of Alumina at Steelmaking Temperatures

contributor:
Kay, D.A.R.
Metallurgy and Materials Science

subject:
Materials Science and Engineering
Metallurgy
Materials Science and Engineering

abstract:
A high temperature electrochemical formation cell

[equation removed]

has been used to determine the standard free energy of formation of alumina at steelmaking temperatures. The temperature variation of the free energy was determined as

[equation removed]

in the temperature range 1700º-1850ºK. These results are in good agreement with those reported in the literature at ~1300ºK using a similar technique but are 3.3% more positive than the generally accepted thermochemical value at 1800ºK. In order to confirm the absence of any systematic errors in the above cell, the following cell was designed and operated in the temperature range 1641º-1785°K

[equation removed]

The results from this cell are in good agreement with those of the first cell within the experimental error.

The Third Law analysis of the present data gives an average value of the standard heat of formation of alumina at 298ºK, Hº₂₉₈, of -392.6 (± 0.92) kcal/mole which is in good agreement with the Third Law analysis of lower temperature cell (~1300ºK) data and the values of ΔHº₂₉₈ calculated from phase equilibria and solution calorimetric data in mineralogical systems. All these values are at variance with the presently accepted "best" value of ΔHº₂₉₈ = -400.40 (± 0.3) kcal/mole from oxygen bomb calorimetry, although the average of all bomb calorimetric data is in agreement. Using the presently determined ΔGºf (Al₂O₃), the temperature dependence of K = h²Al h³₀, the aluminum deoxidation constant, can be calculated as

[equation removed]

The value of K = 4.7x10⁻¹³ at 1600ºC is in good agreement with the most recent work of Jacquemont et al. (1973) and is an order of magnitude higher than previous calculations. An independent calorimetric determination of ΔHº₂₉₈ using a method other than oxygen bomb calorimetry is therefore suggested.

abstract: Doctor of Philosophy (PhD)


title: Shell Model States in ¹³⁸La

contributor:
Summers-Gill, R.G.
Physics

subject: Physics Physics

abstract:
A ·cornbinationof particle andy-r';'ij' spectroscopy. has: . ,: '., \". '. " ~:'" been utilized' to elucidate the nuclear structure ,~'f 138La . The'~in

The complementary information from the proton transfer and neutron pick-up reactions, together with their spin assignments, is used to analyze the wave functions for the twelve lowest levels. These appear to be simple shell model states arising from the coupling of a neutron hole in the 2d₃⁄₂ or 3s½ orbit to the j = 7/2 or 5/2 proton configurations observed at low energy in ¹³⁹La.

Two groups of negative parity states, predicted by the simple shell model, have also been identified. Unfortunately only tentative spin assignments, based on the 2J+1 rule for spectroscopic strengths have been possible for most of these because the (p,n) reaction does not populate the many high spin states involved.

A lowest seniority shell model calculation, employing the surface delta interaction, was carried out for the low-lying levels. Spectroscopic factors are calculated for both the proton transfer and neutron pick-up reactions. A comparison with the experimental findings shows disappointing agreement.

abstract: Doctor of Philosophy (PhD)


title: Design and implementation of model based controller for systems with input saturation and model mismatch

contributor:
Taylor, P.A.
Wright, J.D.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract: This research deals primarily with the design and implementation aspects of model based digital control algorithms. The performance of model based digital controllers degrades whenever the process input saturates or the process model is significantly different from the true process. Simulations and experiments have been performed to identify the saturation problems in model based controllers and four algorithms were proposed to compensate for this problem. The saturation problem was generalized to cover all situations where the output computed by the model based controller cannot be applied to the actual process. This includes actuator saturation, operator override, temporary actuator failure and asynchronous control. A generalized implementation scheme of model based controllers was proposed and a dramatic performance improvement was observed by using such an implementation scheme. The second part of the thesis focuses on the robustness aspect of model based controllers. The work reported here takes a time domain, rather than the traditional frequency domain approach. A new stability theorem and corollaries for uncertain systems have been derived and applied to simulated processes. A new analysis method, Error Band Method (EBM), has been developed to analyse the performance of a dynamic uncertain control system. Monte Carlo simulations have been performed to verify the validity of this approach. The method was extended to include controller design and controller comparisons. This methodology provides a different perspective to the analysis and design of uncertain model based digital control system.

abstract: Doctor of Philosophy (PhD)


title: Gamma-Ray Studies of ⁷¹Ge

contributor:
Kuehner, J. A.
Physics

subject: Physics Physics

abstract:
The ⁶⁸Zn(α,nϒ) ⁷¹Ge reaction has been used to study the gamma decays of levels below 1.3MeV excitation in ⁷¹Ge. Gamma-ray angular distributions and angular correlations of gamma-gamma cascades were measured, using Ge(Li) detectors. The results were analysed using the compound Nucleus Statistical Reaction Model, to determine the angular momenta of most of the leveIs known in ⁷¹Ge below 1.3MeV, and the multipole mixing ratios of their gamma decays.

The deduced level scheme has been compared with the predictions of a nuclear model calculation, in which the odd neutron in ⁷¹Ge is coupled to the collective quadrupole vibrations of the ⁷⁰Ge core. The model allowed for a pairing residual interaction between the core neutrons, and anharmonic terms in the core vibrations.

abstract: Doctor of Philosophy (PhD)


title: Empirical modeling and correlation of the interactions between blood and artificial surfaces

contributor:
Brash, J.L.
Chemical Engineering

abstract: Blood coagulation and protein adsorption were studied on a series of model surfaces. Silanes were used to covalently attach chemical groups (including sulfonate. amine, polyethylene oxide (PEO), lysine methyl, and octadecyl) to pure silica substrates. Surface chemical analysis by x-ray photoelectron spectroscopy (XPS) was used to quantify the elemental composition of these surfaces. All silane layers were estimated to be monolayers or less with thickness in the range 0.2 nm (for methyl groups) to 2.0 nm (for PEO). Contact angles were measured to help quantify the interaction between the model surfaces and pure solvents (water, glycerol, dimethyl sulfoxide (DMSO)). The data were fit to established interfacial tension (interfacial free energy) models but none was found to be adequate. A new empirical model, not related to surface energetics, was developed and demonstrated to be capable of fitting the data more precisely. Small deviations from the empirical model (± 2° to 8°) for DMSO and water contact angles were attributed to the possible influence of surface charge. Protein adsorption kinetics on the model surfaces was measured using ¹²⁵I-labeled fibrinogen and albumin as single proteins under static conditions. A simulation of transport and reaction in this experimental system was written and used to fit data to proposed models for protein adsorption. A simple bilayer mechanism was found to fit the kinetic data better than a number of multistate monolayer models for adsorption. The adsorption of fibrinogen from plasma was also measured in order to investigate a possible relationship between the Vroman effect and surface activated blood coagulation. A surface activated blood coagulation assay based on the partial thromboplastin time test was used to characterize the blood compatibility of model surfaces prepared on glass test tubes. The kinetics of cleavage of a fluorogenic substrate for thrombin was measured in real time on surfaces which were assumed to be closely comparable to those prepared on pure silica. Clotting times ranging between 2 and 11 minutes were measured. A correlation analysis was performed using surface chemistry, contact angle, protein adsorption, and blood coagulation data. Clotting times were found to be empirically related to surface chemistry, but not to fibrinogen adsorption or the Vroman effect. The Vroman effect for fibrinogen was found to be predictable in most cases given only single component fibrinogen adsorption data. Fibrinogen adsorption from buffer was found to increase with sulfur (sulfonate) content and decrease with nitrogen (amino) content, but contrary to suggestions in the literature was not a strong function of wettability. A multivariate approach to studying the interactions between blood, proteins and model surfaces proved to be a practical approach to a complex problem. It was demonstrated that univariate relationships are often inadequate in their ability to explain the interfacial behavior of blood and its elements, and in fact may lead to erroneous conclusions

abstract: Doctor of Philosophy (PhD)


title: The Preparation and Chemistry of Oxadiazolinones and Oxadiazolines

contributor:
Warkentin, J.
Chemistry

subject: Chemistry Chemistry

abstract: The objectives of this work were fourfold. Firstly, the oxidation of semicarbazones with lead tetraacetate was examined from the point of view of products and of mechanism, as related to the mechanisms of other lead tetraacetate oxidations of carbonyl derivatives. Secondly, the chemistry of the acetone semicarbazone oxidation product, 5,5-dimethyl-Δ³-1,3,4-oxadiazolin-2-one was investigated. Thirdly, the chemistry of the methyl Iithium addition product of 5,5-dimethyl-Δ³-1,3,4-oxadiazolin-2-one, 2-hydroxy-2,5,5-trimethyl-Δ³-1,3,4-oxadiazoline, was studied mainly from the aspect of its novel radical chain thermal decomposition. Fourthly, a general principle regarding radical pathways was put forward.

abstract: Doctor of Philosophy (PhD)


title: Oxo and Oxyfluoro Complexes of Iodine (V) and (VII)

contributor:
Gillespie, R. J.
Chemistry

subject: Chemistry Chemistry

abstract:
The behaviour of potassium iodate, iodic acid and various other iodine V compounds as solutes in fluorosulfuric acid has been studied using cryoscopy, conductivity, Raman and nmr spectroscopy. Evidence has been obtained for the species IOF₂SO₃F as the major product of the reactions, and this species has been shown by Raman spectroscopy to be fluorosulfate bridged. The IO₂⁺ and IOF₂⁺ cations have been prepared from the corresponding oxyfluorides and a strong fluoride ion acceptor and characterized for the first time.

The structure of IO₂F₃ has been the subject of several publications and although they all agree that the molecule is polymeric, no definite conclusion on the polymer size had been reached. It has been shown in this work, that IO₂F₃ is a cis oxygen bridged trimer in the solid, liquid and solution phases. The chemistry of IO₂F₃ with strong Lewis acids was studied and it was found to be a fluoride ion acceptor forming polymeric complexes of the type (IO₂F₄ MF₄)n. The previously unknown salt KIO₂F₄ was prepared and characterized and it was found to exist as the trans isomer in the solid and in acetonitrile solution but as a mixture of cis and trans in solvents where fluoride ion transfer can occur. IOF₅ has previously been shown not to be a fluoride ion donor but the ¹⁹F nmr and Raman spectrum of solutions containing IOF₅ and SbF₅ indicated an interaction between IOF₅ and the Lewis acid through the oxygen. At low temperature in SO₂F₂ as a solvent, 1:1 and 1:2 complexes were observed. An attempt to prepare periodyl fluoride IO₃F, the last of the series of iodine (VII) oxyfluorides proved unsuccessful.

abstract: Doctor of Philosophy (PhD)


title: Quasigraphs in n-Dimensional Manifolds

contributor:
Lane, N.D.
Mathematics

subject: Mathematics Mathematics

abstract: A definition of quasigraphs in n-dimensional manifolds in given. A continuous family of quasigraphs is then introduced and the intersection and support properties of these quasigraphs are studied.

abstract: Master of Science (MS)


title: The Luminescence of Perhydro, Deutero, and Halo-Phenylacetylenes in Rigid Solutions at 77ºK

contributor:
Laposa, J. D.
Chemistry

subject: Chemistry Chemistry

abstract:
The fluorescence, and phosphorescence spectra of phenylacetylene-H₆, -D₁, -D₅ and -D₆ as dilute (10⁻³ or less) solutions at 77°K are reported.

Vibrational analyses of the fluorescence and phosphorescence spectra of these compounds in polycrystalline methylcyclohexane indicate that the geometries of the emitting singlet (S₁) and triplet (T₁) states are different. The fluorescence spectra are interpreted in terms of a weak allowed component and a strong forbidden one, the latter based on one quantum of non-totally symmetric b₂ vibrations. The main progression in up to five quanta of the ring breathing fundamental is explained to signify a planar, slightly expanded regular ring geometry of S₁. The phosphorescence spectra show a relatively long progression in the totally symmetric C-C ring stretching mode indicating a planar, non-regular-hexagonal ring in the T₁ state.

Polarization of the fluorescence and phosphorescence spectra of phenylacetylene-H₆ in a rigid glass at 77ºK are used to assign the orbital symmetries of the T₁ state as well as the symmetries of the major bands of these spectra.

The phosphorescence lifetimes of -H₆, -D₁, -D₅ and -D₆ in rigid glasses at 77°K show that deuterium substitution for the single acetylenic hydrogen has almost the same effect as deuterium substitution for all five ring hydrogens in altering the radiationless deactivation of T₁. These result are interpreted on the basis of a current theory of radiationless transitions.

The effect of halo-substitution in the ring on radiative and non-radiative rates is investigated for seven monohalophenylacetylenes. The phosphorescence lifetimes (in 10⁻³ glassy solutions) decrease markedly with increasing mass of the halogen, and the effect is greatest for the para position. Heavy atom perturbation affects the ∫(d values of the S₁ ← S₀ and S₁ ← S₀ absorptions only slightly. Intersystem crossing yields are also found to increase with halogen mass. The vibrational analyses of the phosphorescence spectra of the halophenylacetylenes (in rigid solutions at 77ºK) indicate the presence of two subspectra. Subspectrum I consists of the 0,0 band and bands due to in-plane modes (mainly totally-symmetric) while Subspectrum II arises from out-of-plane modes. Subspectrum II is found to increase relative to Subspectrum I with halogen substitution. Polarization measurements of the main bands of the phosphorescence spectra are interpreted in terms of contributions from several spin-orbit mechanisms.

abstract: Doctor of Philosophy (PhD)


title: Preparation, Structural Characterization and Electrical Properties of Some Polyatomic Cations of Mercury

contributor:
Gillespie, R.J.
Chemistry

subject: Chemistry Chemistry

abstract:
The preparation of a number of new compounds containing mercury in formally low oxidation states is reported. The preparations are described and Raman spectra are reported for Hg₂(AsF₆)₂.SO₂, Hg₂(AsF₆)₂, Hg₂(Sb₂F₁₁)₂.SO₂, Hg₂(SbF₆)₂.SO₂, Hg₂(SbF₆)₂, and Hg₂(SO₃F)₂. All of the mercurous salts have been prepared for the first time. The preparations of Hg₃(AsF₆)₂ and Hg₃(Sb₂F₁₁)₂, both of which contain the Hg₃²⁺ cation are presented. The Hg₄²⁺ cation, which has not been identified previously, is present in Hg₄(AsF₆)₂. The preparation of this compound and its Raman and UV-visible spectra are discussed. Raman spectroscopic and x-ray crystallographic studies show that the ions are linear, and that the bond lengths increase in the order Hg₂²⁺ < Hg₃²⁺ < Hg₄²⁺.

Two new compounds containing infinite, linear, non-intersecting chains of mercury atoms in two mutually perpendicular directions have been prepared. The bonding in the metal atoms chains can be described as metallic, with the charge delocalized over the mercury atom chains.

An experimental technique for measuring the electrical conductivity of these extremely hygroscopic compounds is described, and conductivity and optical studies show that the compounds are anisotropic, metallic conductors. They constitute a new class of anisotropic materials.

abstract: Doctor of Philosophy (PhD)


title: Nuclear Structure of Two Transitional Nuclei: ¹⁵⁴₆₄Gd₉₀ and ¹⁵²₆₃Eu₈₈

contributor:
Waddington, J. C.
Physics

subject: Physics Physics

abstract:
The nuclear structure of two transitional nuclei, ¹⁵⁴₆₄Gd₉₀ (doubly-even) and ¹⁵²₆₃EU₈₉ (doubly-odd) has been investigated by single neutron and proton transfer reactions. In general, it was found that the unified nuclear model with the inclusion of pairing, Coriolis and ΔN=2 interactions gives a good description of these nuclei. The reaction strengths to the many two-quasiparticle states have been predicted by the distorted wave Born approximation.

Experimentally deduced values of the splitting energies for the various two-quasiparticle configurations in ¹⁵⁴Gd and ¹⁵²Eu have been found to be in reasonable agreement with a calculation based upon a zero range interaction between the two unpaired particles.

abstract: Doctor of Philosophy (PhD)


title: Studies in Crystalline and Amorphous Structures in PbO-V₂O₅-P₂O₅

contributor:
Calvo, Crispin
Physics

subject: Physics Physics

abstract:
The crystal structures of PbV₂O₆ and α-VPO₅, both from within the glass-forming region of PbO-V₂O₅-P₂O₅, have been determined by X-ray methods to help provide models for the local structure of the glass. A temperature dependent displacive disordering of oxygen atoms is found in α-VPO₅. A specimen has been studied which is still ordered at room temperature but appears to be vanadium rich.

X-ray scattering intensities, measured for five compositions of V₁₊ᵪP₁₋ᵪO₅ glass, are compared with a model for the local structure of the glass based upon structural features from a-VPO₅. Available data on the physical properties of the glass, such as density and electrical conductivity, are discussed in relation to the proposed structural model.

Methodological problems of X-ray scattering from glass, involved with Compton scattering and multiple scattering, are discussed.

abstract: Doctor of Philosophy (PhD)


title: LASER RAMAN SPECTROSCOPIC INVESTIGATIONS OF SOME FLUOROXENON COMPOUNDS

subject: Chemistry Chemistry

abstract:
The Raman spectra of a number of salts of fluoro- and oxy-fluoro cations of xenon compounds, in a variety of oxidation states are reported. The preparation of some of these compounds is reported for the first time. Characteristic frequencies along with comprehensive assignments are given for the Xe₂F₃⁺, XeF⁺, XeF₃, XeOF₃⁺, Xe₂OF⁺, XeF₅⁺ and Xe₂F₁₁⁺ cations, and some other related compounds both in the solid state and in HF solution. Reactions of XeF₂ with BF₃ have been shown to give the new BF₄⁻ salts, XeF⁺BF₄⁻ and Xe₂F₃⁺BF₄⁻, while the reaction of XeF₄ with AsF₅ has been shown to give the new salt XeF₃⁺As₂F₁₁⁻⁻. Largely, by the aid of Raman spectroscopy, the molecular geometries of these cations are shown to be in accord with electron pair repulsion theory.

Direct spectroscopic evidence is presented for the first time for the presence of weak covalent interaction, i.e., fluorine bridges, in a number of the salts studied. With the aid of the available X-ray crystallographic data, and the vibrational data presented, it was found that fluorine bridge interactions increase in strength in the series XeF₅⁺ < XeF₃⁺ < XeF⁺. Thus, in contrast to the previously supposed order the fluoride ion donating ability of the fluorides was found to decrease, in the order XeF₆ > XeF₄ > XeF₂.

A useful correlation has been found between the xenon-fluorine stretching frequencies and the bond lengths. This correlation has been found to hold for a wide variety of fluorocations, and neutral molecules, in a number of different oxidation states and for a wide range of Xe-F bond lengths, including the Xe---F bridge bonds.

abstract: Doctor of Philosophy (PhD)


title: Fréchet Algebras with Schauder Bases

contributor:
Husain, T.
Mathematics

subject: Mathematics Mathematics

abstract: Let A be a Fréchet algebra with the defining sequence {qn}n≥1 of seminorms and identity e. Let {xᵢ} be a Schauder basis in A. Then each xεA, can be written as: x = ᵢ∑₁αᵢxᵢ, where {αᵢ} is a unique sequence of complex numbers depending upon x. αᵢ's are called coordinate functionals or coefficients. This thesis is concerned with some relations among coefficients, seminorms and the identity, e of A. Further, it is shown that each multiplicative linear functional on A is continuous provided a certain condition is satisfied. Some of the results needed to prove the above results are shown to be true for Fréchet spaces. Finally, a representation theorem for Fréchet * - algebra is given.

abstract: Doctor of Philosophy (PhD)


title: Fermi surface of donor and acceptor graphite intercalation compounds

contributor:
Datars, W.R.
Physics

subject: Physics Physics

abstract: The Fermi surfaces and the electronic properties of the donor-type stage-1 C₈K and stage-2 C₂₄K, as well as the acceptor-type stage-2 BiCl₃, stage-3 HgCl₂ and stage-3 SbF₅ graphite intercalation compounds were investigated by means of the de Haas-van Alphen effect. The dHvA spectra of the stage-1 C₈K exhibit two dHvA frequencies, 3126 T and 4250 T. The corresponding effective masses were 0.86 m₀ and 0.92 m₀, respectively. The angular dependence of the dHvA frequencies for a direction within ±18° of the c-axis showed that there are both three-dimensional and two dimensional parts of the Fermi surfaces in C₈K. The three-dimensional Fermi surface has a cross-sectional area corresponding to the dHvA frequency of 3126 T. The charge transfer per potassium atom measured from the dHvA effect is 0.97. This implies that the potassium is ionized completely. These dHvA experimental results support both the Tatar and Rabii model and the revised Ohno, Nakao and Kamimura model for C₈K. Two dominant dHvA frequencies were obtained in stage-2 C₂₄K. They are 286 T and 2570 T, respectively. The predictions of Blinowski's model are in agreement with the experimental data. The charge transfer per potassium is found to be 0.88. This suggests that the potassium s-band is above the Fermi level in C₂₄K. The dHvA measurements for the acceptor compounds show that the stage-2 BiCl₃ GIC had two dHvA frequencies, 327T and 1012T, and each stage-3 compound had three dominant frequencies. They are 121T, 523T and 664T for HgCl₂, and 172T, 656T and 852T for SbF₅. The cyclotron masses corresponding to the dHvA frequencies for these compounds were measured from the temperature dependence of the dHvA amplitudes. The theoretical predictions of the dHvA frequencies and the cyclotron masses from the Blinowski's band models for stage-2 and stage-3 compounds are in agreement with the experimental results. The angular dependence of the dHvA frequencies show that the Fermi surfaces in these acceptor compounds are cylinders. This proves the two-dimensionality of the band structures of the Blinowski model. In addition, the charge transfer coefficient per carbon atom is directly determined from the observed sum of the dHvA frequencies for each of the acceptor compounds. The fractional charge distribution along the c axis of the stage-3 compounds is found to be between the uniform charge distribution model and the metallic sandwich model.

abstract: Doctor of Philosophy (PhD)


title: Electric Field Gradient at ¹⁸¹Ta Nuclei in Hafnium Coordination Compounds

contributor:
Prestwich, W. V.
Physics

subject: Physics Physics

abstract:
The quadrupole interaction of ¹⁸¹Ta with the electric field gradient (EFG) at Hf sites in the coordination compounds (NH₄)₃ HfF₇, K₃HfF₇ and Hf(acac)₄ has been measured by the method of differential perturbed angular correlations.

The heptafluorates which possess identical crystal structures were found to produce vastly different EFG's at the sites of the ¹⁸¹Ta probe nuclei. Over the range from liquid nitrogen to room temperature, the EFG in (NH₄)₃HfF₇ was observed to change from a static to a dynamic nature due to the reorienting HfF₇⁻³ ion add the effects of the dynamic NH⁴⁺ ions. No comparable time-dependent effects were observed in K₃HfF₇ which required a two site static model for the Hf atoms at liquid nitrogen temperature and a one site model, with only a slight dynamic modification, at room temperature. The results were found to be in agreement with other NMR and X-ray studies of these compounds.

The measurement of the EFG at the metal site in Hf(acac)₄ yielded a large asymmetry value that is discussed in terms of the crystal structure and type of ligand bonding involved in this octocoordinated complex. Comparison of the results for synthetic and irradiated samples of Hf(acac)₄ gave no indications of radiation produced damage to the crystal structure. Evidence for the existence of two sites with different asymmetry parameters as suggested by a previous study was not found.

A detailed investigation of instrumental effects in perturbed angular correlation measurements was also carried out. This study included the measurement and correction of system nonlinearities and background anomalies in time spectra measurements.

Finally, a precise measurement of the half-life of the 482 keV level in ¹⁸¹Ta was performed using the delayed coincidence method.

abstract: Doctor of Philosophy (PhD)


title: Structures of hydroxy/alkoxy substituted carbenium ion systems

contributor:
Childs, R.F.
Chemistry

subject: Chemistry Chemistry

abstract: The structures of two series of hydroxy/alkoxy substituted carbenium ion systems have been explored in this thesis. The structural effect of systematic substituent changes on cationic geometries has been probed and related to variable charge distributions within these cations. The structures of three 2-substituted 6-ethoxy-tetrahydropyrylium salts have been determined with use of x-ray crystallographic and NMR spectroscopic techniques. It has been shown that the conformations and structures of the tetrahydropyrylium ions observed in the crystalline state are similar, and that these conformations are also present in solution. The six-membered ring in each cation exists in a shallow half-chair conformation with the cationic centers C₆, C₅, O₁ and O₆ having an approximately planar arrangement. These cations each exhibit a Z-conformation about the O₆-C₆ bonds. Systematic analysis of the bond distances obtained has indicated severe C-O bond length distortions and has suggested variable degrees of positive charge delocalization to C₂ and C₇ in these systems. The conformations, details of C-O bonding and closest cation-anion contacts observed have been discussed in terms of the concept of stereoelectronic control. The crystal structures of three alkyl-substituted hydroxycyclopropylcarbinyl cations have also been determined. Each cation adopts, or approximately adopts, a bisected conformation. The systematic cyclopropyl bond length distortions observed, namely vicinal bond lengthening, distal bond shortening and C₁-C₂ bond contraction when compared to those observed for neutral cyclopropyl ketones, have been related to the degree of charge delocalization into the cyclopropyl ring in each cation and to variable substituent charge stabilizing ability. Semi-empirical and ab initio calculations have also been performed to further probe the nature of bonding within these systems. The optimized gas phase conformations and structures are very similar to those observed crystallographically. However, theory appears to underestimate the degree of structural distortion experimentally observed.

abstract: Doctor of Philosophy (PhD)


title: Time-frequency analysis and design of signals: The Wigner distribution and its applications

contributor:
Wong, Kon Max
Luo, Tom Zhi-quan
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract: Time frequency representations provide us with an efficient way to process non-stationary signals and systems with time-dependent spectrum. In this thesis, a tutorial review of several time-frequency representations is presented. The historical development and the properties are discussed with the emphasis being placed on the Wigner distribution (WD). Three important applications of time-frequency representations are studied. They are the tracking of instantaneous frequency, high resolution estimation of frequencies in the non-stationary environment, and the design of signals for optimum simultaneous estimation of time delay and Doppler shift. An efficient way to calculate the Cramer-Rao lower bound for the time-varying frequency estimation is obtained. The theoretical performance of the WD when applied to the estimation of this time-varying frequency is derived and the simulation examples are provided. Using the properties of the instantaneous spectrum, new algorithms are developed which can accurately estimate the frequencies of the non-stationary signals with fast varying amplitude. A particular example of the applications is the frequency estimation in Search and Rescue Satellite (SARSAT). For tests on real SARSAT signals, our new algorithms exhibit superior performance to other spectrum estimation methods. The Cramer-Rao bound (CRB) for the joint time delay and Doppler shift estimation is derived and it is proved that the joint estimates of these two parameters using time-frequency representations are optimum under high SNR in the sense that it is unbiased and the variance reaches the CRB. Several efficient methods are developed to obtain the optimum signal for the joint time delay and Doppler shift estimation under different practical constraints.

abstract: Doctor of Philosophy (PhD)


title: One and Two Photon Annihilation Processes in a Strong Magnetic Field

contributor:
Sutherland, P. G.
Physics

subject: Physics Physics

abstract: We present theoretical calculations of the annihilation rates for one and two photon decay of ground state positronium in a strong magnetic field, of order (10¹²-10¹³) Gauss such as assumed for neutron star surfaces. The calculation indicate that the one photon process at field of 10¹³ Gauss is of order (10ˉ⁴) compared to the two photon process. Consequently, a one photon annihilation line at 1.022 MeV is not expected in the spectra of neutron stars. The two photon rate is of order (5x10¹³ secˉ¹) at 10¹³ G; the half width is 43 keV. Thus, at such fields, the two photon line is fairly narrow and not smeared out through the magnetic field effects.

abstract: Master of Science (MS)


title: Electro-absorption in InGaAs-GaAs strained-layer multiple quantum well waveguide modulators

contributor:
Jessop, P. E.
Engineering Physics

subject:
Engineering Physics
Nuclear Engineering
Other Engineering
Nuclear Engineering

abstract: Electric field induced changes in the excitonic band-edge absorption spectra of Multiple Quantum-Well (MQW) structures were investigated theoretically and experimentally. Three In(x)Ga(1-x)-GaAs quantum-well p-i-n waveguide structures were designed, and were then grown by the National Research Council of Canada. Band edge absorption changes with field were then investigated using light incident perpendicular to the sample surface. Theoretically, a comparison was made of three different exactly solvable methods for calculating quantum-well energies in an electric field, both with and without conduction-band non-parabolicity. An exactly solvable method was used to calculate the hole dispersion and thereby determine the heavy-hole parallel effective mass. By using calculated wavefunctions, and these mass values, a numerical method was used (Wu, 1989) to solve for the exciton binding energies. After determining broadening factors, the absorption edge was calculated at low and moderate fields for three In(x)Ga(1-x)As-GaAs structures for various fields. At high fields, a different Franz-Keldysh type of absorption calculation was developed. Comparisons vs. experiment were favourable, but some discrepancy was noted. Slab and rib waveguide modulators, with operating wavelengths from about 970nm to 1035nm, were processed from the three material growths. Waveguiding transmission spectra again agreed favourably with theory, although some differences were seen. The modulators typically exhibited greater than 20 dB of switching over a 40nm range with less than 2 dB of low-bias absorption loss. Switching speed was not examined. Theoretical analysis of different structures revealed many trade-offs, in design, with 3% to 17% indium, and 6.5nm to 13nm well-widths being acceptable.

abstract: Doctor of Philosophy (PhD)


title: Control and operability of recycle processes

contributor:
Taylor, P. A.
Wright, J. D.
Chemical Engineering

abstract: This thesis presents an investigation into the effect of recycle on the dynamic controllability and operability of chemical processing systems. In particular, this investigation focuses on the effect that recycle has on the behaviour of individual chemical units when they are configured such that the product of the last unit is returned as a partial feed to the first unit. An experimental extractive distillation unit, which separates a mixture of methanol and acetone using a water solvent, was chosen for this study. Two aspects of this system were highlighted in this thesis. The first is that the system is subject to, and is to be controlled against, feed flow and compositional disturbances. The second aspect is that the system contains deadtime, and the analysis techniques must take this into account. There are currently several techniques for analyzing the dynamic behaviour of chemical systems (without resorting to exhaustive numerical simulations). It is demonstrated that these techniques contain severe limitations which preclude their use for a recycle system. Modifications presented in this thesis to these techniques allow for their successful application on a recycle system; furthermore, these modifications are not limited to recycle systems exclusively, but should be utilized on chemical engineering systems in general. In particular, these modifications are: (1) A methodology was formulated for determining interaction for regulatory control systems. To date, dynamic interaction techniques were constrained to servo systems; the technique presented in this thesis is the first to consider the regulatory interactions of the system. (2) Interaction techniques were modified to take into account deadtime, as all present techniques have the shortcoming of being invariant to deadtime. (3) A technique for simplifying recycle transfer functions was formulated. This was necessary because recycle transfer functions formed from their constituent subsystems cannot be inverted to the time domain or used to design controllers. These techniques were applied to the extraction unit and compared against simulations to demonstrate their effectiveness. The large effect that recycle has on the open and closed loop response of this system was also demonstrated, illustrating the importance of considering the response of the entire system, and not just its component parts.

abstract: Doctor of Philosophy (PhD)


title: New Polyatomic Cations of Sulphur, Selenium, Tellurium and Bismuth

subject: Chemistry Chemistry

abstract:
A number of new compounds containing polyatomic cations of the chalcogens have been prepared and their structures investigated. In particular methods for preparing heteroatomic cations containing two of the elements in the same cation have been extensively studied for the first time. Particular emphasis has been given to the preparation of crystalline samples suitable for the investigation of structure by x-ray crystallography. In addition some structural studies have been made by Raman spectroscopy.

The following compounds containing homopolyatomic cations have been prepared by the reaction of ASF₅ or SbF₅ with the appropriate element in solution in SO₂ and their structures investigated: S₁₆(AsF₆)₂, Se₁₀(AsF₆)₂, Te₆(SbF₆)₂, and TeAsF₆. By reactions between two different homopolyatomic cations or by reactions of a single homopolyatomic cation with one of the elements sulphur, selenium or tellurium the following compounds of new heteropolyatomic cations were prepared and their structures studied. Te₂Se₈(AsF₆)₂.SO₂, Te₃.₇Se₆.₃(AsF₆)₂, Te₂Se₂(AsF₆)₂, Te₃S₃(AsF₆)₂ and S₂Se₈(AsF₆)₂.

In a rather limited investigation of the reactions of bismuth with AsF₅ and SbF₅ the following compounds containing the Bi₅³⁺ cation have been prepared and characterized by Raman spectroscopy: Bi₅(AsF₆)₃2SO₂ and Bi₅(SbF₆)₃. A polymeric compound of composition BiF₂.AsF₆ was also prepared.

abstract: Doctor of Philosophy (PhD)


title: Characterization, measurement and prediction of the turbulent flow in stirred tanks

contributor:
Wood, Philip Eric
Chemical Engineering

abstract: Characterization of the Rushton turbine (RT) and pitched blade turbine (PBT) impellers was undertaken with two objectives: (1) development of impeller boundary conditions which can be generally applied to CFD simulations of stirred tank flows for predictive purposes, and (2) accurate characterization of the turbulence quantities k and ε for use in model development and verification. Since the flow field for the RT is well characterized in the literature, work on this impeller proceeded directly to a fundamental model of the discharge flow. Using this swirling radial jet (SRJ) model, it was possible to accurately predict the impeller boundary condition, including k and ε. The predicted boundary condition was used in a three dimensional CFD simulation of the entire flow field. The results of this simulation accurately reproduce mean velocity profiles, the decay of k and ε in the bulk of the tank, and details of the flow behind the baffles. Characterization of the PBT commenced with mean velocity and flow visualization studies of the impeller discharge zone for various geometries. It was found that there is a definite transition of the entire time averaged flow field from a single circulation loop, to two circulation loops, which occurs at a specific off bottom clearance. It was also shown that the boundary condition is affected by feedback from this transition in the flow field. The time varying characteristics of the flow field were examined in some detail. Various proposed methods of estimating ε were applied, and the results compared. It was found that autocorrelation function methods revealed useful physical information about the flow, particularly the existence of not only the dominant blade passage frequency (BPF), but also a second, low frequency component in the flow. The effects of these frequencies on the calculated value of ε were examined. It has been possible to characterize the boundary conditions for both the RT and the PBT impellers, using both theoretical and experimental methods; and to show that mathematical modelling and CFD simulations based on the k-ε model can yield accurate and useful information about the flow field.

abstract: Doctor of Philosophy (PhD)


title: Sulphur Isotope Fractionation in Troilite Oxidation, Evaporation and Dissociation, and the ³⁴S/³²S Ratios in the Canyon Diablo Metallic Spheroids

contributor:
Thode, H.G.
Physics

subject: Physics Physics

abstract:
Canyon Diablo metallic spheroids are roughly spherical in form, approximately 1 mm in diameter, consist mainly of nickel and iron and are found in conjunction with Canyon Diablo meteorite fragments in the vicinity of Barrlnger Meteorite Crater, Arlzona.

Conventional chemical techniques and a gas source mass spectrometer, using SF₆ as the analysis gas, were used to measure the sulphur contents and ³⁴S/³²S ratios in spheroid samples of different sizes. Also, material was removed from various depths within the spheroids by means of ablation using a mixer/mill so that the radial dependence of the sulphur contents and ³⁴S/³²S ratios could be studied. This was the first time that the ³⁴S/³²S ratios in the Canyon Diablo metallic spheroids have been measured.

It was found that the spheroids are enriched in ³⁴S compared to the Canyon Diablo meteorite fragments and that the enrichment is greater in the smaller spheroids than in the larger ones. Also, the layers nearest the surface are more enriched than the inner portions.

In order to investigate the possible causes of this enrichment the sulphur isotope effects associated with the oxidation, dissociation and evaporation of the meteoritic mineral troilite, (FeS), were measured. The troilite samples were heated in a furnace at approximately 1200ºC in a dry-air atmosphere for oxidation and in a vacuum for dissociation and evaporation. In the oxidation experiment it was found that the residue has a σ³⁴S value relative to the starting material of approximately -0.33 ‰ apparently independent of the extent of reaction. Also, dissociation and evaporation occur simultaneously in a two-branch reaction with the σ³⁴S values of the residues strongly dependent on the extent of reaction in a manner similar to the Rayleigh distillation process. The sulphur isotope effects associated with evaporation and dissociation were found to be (+4.8 ± 0.3) ‰ and (+12.9 ± 0.3) ‰ respectively. Consequently, the σ³⁴S values (relative to the starting material) of the initial products are respectively about -4.8 ‰ and -12.9 ‰. This is the first time that the sulphur isotope effect associated with the high temperature oxidation of troilite has been measured. It is also the first time that the sulphur isotope etfect associated with either the vacuum dissociation or evaporation of troilite has been measured. This latter information has proven useful in the interpretation of the sulphur content and σ³⁴S data obtained from the analyses of lunar soils. The equations governing the relationships between the σ³⁴S values of the residue and products in two-branch first-order reactions are presented.

Published hypothetical accounts of the events that the Canyon Diablo metallic spheroids having their present chemical composition are reviewed and discussed. The following new explanation is presented that is consistent with the isotope ratio data and the chemical compositional differences between the spheroids and the meteorite fragments. It is suggested that the Canyon Diablo meteoroid included a portion containing greater nickel and cobalt contents than do the fragments presently found at the crater site. This portion was shock-melted by the impact and splash-dispersed to form the spheroids. The ³⁴S enrichment occurred when the spheroids lost sulphur by dissociation/evaporation upon exposure to the near-vacuum of the meteoroid's train.

abstract: Doctor of Philosophy (PhD)


title: Magnetic resonance studies of organometallic cations and clusters

contributor:
McGlinchey, M. J.
Eaton, D. R.
Chemistry

subject: Chemistry Chemistry

abstract: This thesis describes the application of magnetic resonance methods to some problems in organometallic chemistry. The reactions of nitroso compounds with the (cyclohexadienyl)Fe(CO)₃ cation have been investigated by using ESR spectroscopy and yield nitroxides of the type (OC)₃Fe(C₆H₇)(Ar)N-O•, and also the corresponding C₆H₅(Ar)N-O• radical. With bulky nitrosoarenes, such as C₆Me₅NO, isomers are observed in which the aryl ring rotation is slow on the ESR time-scale. The analogous reactions with the cyclohexadienyl cation derived from the B ring of (ergosteryl acetate)Fe(CO)₃ lead to attack at the central carbon, i.e, at C-7. Subsequent hydrogen migration leads to the (5,7-diene)Fe(CO)₃ complex bearing the aryl nitroxide at the 7-position. In contrast, the reaction of ((η⁵-cyclohexadienyl)Fe(CO)₃)⁺BF₄⁻ with 2-methyl-2-nitrosopropane yields the bis(t-butyl)nitroxide radical and the most interesting observation is that the intensity of the ESR signal varies in an oscillatory manner with time. This is the first oscillating reaction that can be followed by ESR spectroscopy The experimental results and a mechanistic rationale are described. In the second part of the thesis, a 1- and 2-dimensional ¹³C NMR study on the carbonyl migration processes in trimetal clusters is discussed. The variable-temperature ¹³C NMR spectra of the clusters (C₅HｎMe₅₋n)MCo₂(CO)₈CCO₂-i-Pr, where n = 5, 4, and 0 and M = Mo and W, reveal the existence of two interconverting rotamers whereby the CpM(CO)₂ vertex is oriented either proximal or distal to the capping carbonyl group. Simulation of the carbonyl exchange process reveals that the migration of CO ligands between Co and Mo has the same activation energy barrier as the interconversion of proximal and distal cyclopentadienyl rings; it is proposed that these fluxional processes are correlated. Use of a capping fragment derived from a natural product such as menthol or podocarpic acid renders the cluster chiral and allows the detection of slowed carbonyl exchange between the diastereotopic cobalt centers. The 125.7 MHz ¹³C NMR spectrum of CH₃CCo₃(CO)₈P(cyclo-C₆H₁₁)₃ at -90°C exhibits a 1:2:1:2:2 carbonyl pattern consistent with the triply-bridged structure found in the solid state, showing that carbonyl exchange can be slowed on the NMR time scale. The coalescence behavior of the ¹³CO resonances can be simulated by invoking a mechanism in which a completely bridge-opened structure is required; local rotation of each Co(CO)₃ vertex is shown to be rapid. 2D-EXCHANGE spectroscopy is used as an independent probe for the fluxional processes and shows that, in accord with the bridge-opened model, all carbonyl sites do not exchange at the same rate. It is also demonstrated that rotation about the cobalt-phosphorus and P-C(ipso) bonds is slowed on the NMR time-scale.

abstract: Doctor of Philosophy (PhD)


title: Magnetic ordering of Erbium and UNi₂Si₂ by neutron scattering

contributor:
Collins, M. F.
Physics

subject: Physics Physics

abstract: The magnetic ordering has been studied in UNi₂Si₂ and erbium single crystals by elastic neutron scattering. Abundant results are given regarding the magnetic structure, magnetic phase transitions, and the effect of a magnetic field on these properties. Three ordered phases are observed in UNi₂Si₂. They have been determined to be an incommensurate longitudinal spin density wave with a magnetic wave vector around q = 0.74c* in the high temperature phase, a simple body-centred antiferromagnet in the intermediate temperature phase, and a square wave in the low temperature phase. This square wave can be viewed equivalently as a longitudinal spin density wave with q = 2/3c* superimposed on a ferromagnetic component. Hysteresis and sample dependence are observed in the low-temperature phase transition. The two lower temperature phase transitions are both first order. The transition to paramagnetism is second order with a critical exponent β=0.35±0.03. When a magnetic field is applied along the c axis, the intermediate temperature phase is destabilised and disappears above a field of 3.5T. Although there is no new phase induced by the field, there exists a reentrant point where the three ordered phases can coexist. Erbium has three distinct ordered phases: the cone phase at low temperatures, the c-axis modulated (CAM) phase at higher temperatures, and the intermediate phase with moments modulated both along c and perpendicular to c. Within these phases the modulation of the moments may lock in to the lattice. The observed weak harmonics of the wave vector q in the basal plane for the cone phase and the q = 1/4c* structure in the intermediate phase can be explained by a basal-plane spin slip model. The effect of magnetic field along the c axis on the magnetic structure is to stabilise the cone phase and to destabilise the intermediate phase. A new lock-in structure with q = 1/4c* in the cone phase is induced by fields above 1.8T. The presence of the field also stabilises the lock-in structure with q = 2/7c* in both the intermediate and the CAM phases.

abstract: Doctor of Philosophy (PhD)


title: Fluorocations of Krypton, Xenon and Bromine(VII)

subject: Chemistry Chemistry

abstract:
The formation, structures and reactions of a number of noble gas species have been investigated by ¹⁹F nmr and Raman spectroscopy. The XeF₃⁺, XeOF₃⁺ and XeO₂F⁺ cations have been prepared from the corresponding xenon fluoride or oxyfluoride and a strong fluoride acceptor such as SbF₅, and characterized for the first time. Their geometries have been determined largely by the aid of ¹⁹F nmr spectroscopy and shown to be in accord with the predictions of the electron pair repulsion theory. The reactions of Xe₂F₃⁺ and XeF₆ with HSO₃F have been shown to give rise to two new fluorosulfate species, (FXe)₂SO₃F⁺ and F₅XeSO₃F, respectively.

The chemistry of krypton difluoride has, until the present work, been very limited. The only known fluoride is KrF₂ and its only reported derivative was KrF⁺ which has, itself, been little studied. A number of new KrF⁺ salts and the previously unknown Kr₂F₃⁺ and Kr₂F₃⁺·xKrF₂ species have been synthesized and studied. The cations of krypton (II) are extremely powerful oxidative fluorinating agents and have been used to prepare the hitherto unknown BrF₆⁺ cation from BrF₅. Attempts to prepare BrF₇ from the BrF₆⁺ cation were not successful. The krypton (II) cations and BrF₆⁺ have been shown to be extremely powerful oxidants, oxidizing O₂ to O₂⁺ and Xe to XeF⁺ under ambient conditions and are probably the most potent oxidants presently known.

Although the majority of the noble gas compounds studied in this work can be approximately formulated as NgFᵪ⁺MF₆⁻ or NgFᵪOy₃⁺MF₆⁻, direct vibrational spectroscopic evidence for a weak covalent interaction between the cation and a fluorine on the anion has been obtained in the case of the krypton (II) salts and XeF₃⁺SbF₆⁻. The X-ray crystal structure of XeF₃⁺SbF₆⁻ has also been determined and supports the view that these "fluorine bridge interactions exhibit a substantial degree of covalent character. Consequently, the electron pair repulsion theory, which has proven highly successful in predicting the geometries of isolated molecules has also proven useful in assessing the preferred relative geometries of the fluorine-bridged anion and cation in solid XeF₃⁺SbF₆⁻ and related noble gas compounds.

abstract: Doctor of Philosophy (PhD)


title: Human sweet taste reactivity: Determinants of hedonic response

contributor:
Weingarten, Harvey P.
Psychology

subject: Psychology Psychology

abstract: This series of experiments explored aspects of sweet taste reactivity in humans, primarily focusing on individual differences which may be relevant for understanding the interactions between taste and food intake. The effect of metabolic state on sweet reactivity depends upon the subjects' underlying hedonic response to sweet (Experiment 1). Subjects can be classified into two major categories: sweet likers (i.e., increased liking with increasing concentration) and sweet dislikers (i.e., decreased liking with increasing concentration). Only the sweet dislikers show an attenuated dislike for concentrated sucrose when deprived; as well, they sip less solution when sated than deprived. Experiment 2 establishes the predictive validity of the hedonic response measures by demonstrating that another known index of hedonic response, facial expressions, can be used to predict sweet liker/disliker status. The sweet liker/disliker distinction correlates strongly with the genetically-determined ability to taste 6-n-propylthiouracil (PROP): PROP nontasters are almost always sweet likers, while sweet dislikers are almost always PROP tasters. This relationship also holds for 7-to-10 year old children, as Experiment 3 shows. Sensory differences may underlie the hedonic differences in taste response, since Sweet dislikers perceive a purer sweet sensation than likers, who report nonsweet (bitter, salty or sour) components in pure sucrose solutions (Experiment 4). The sweet liker/disliker distinction transfers almost perfectly to red, strawberry-flavoured solutions (Experiment 5). However, sweet dislikers show an attenuated dislike for concentrated sweet tastes with the addition of the odour and colour, suggesting that other sensory dimensions of the taste stimulus, such as smell and vision, have an impact on the hedonic value of the taste. These experiments suggest that the sweet liker/disliker distinction reflects an individual difference in taste reactivity which should be accounted for in future explorations of other gustatory encoding, and of the role of taste in eating. Further studies should explore the generality of the sweet liker/disliker distinction to other gustatory stimuli, its predictive value for "real food" preferences and intake, and identify the specific sensory differences which underlie these hedonic response patterns.

abstract: Doctor of Philosophy (PhD)


title: Space Time Finite Elements and Dynamics

contributor:
Dokainish, M.A.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract: Variational methods using the least action principle are used to set up equations for the vibration of systems. Using variational methods, finite elements of structures can be formulated on the space time domain to allow calculation of transient vibratory response to initial conditions and forcing functions. This work attempts to systematize such formulations, discuss limitations in the methods, and compare the accuracy of the two simplest methods to conventional finite difference techniques. Examples are given for single degree of freedom systems, the stretched string, simply supported beam, and plate. No method superior to the Newmark ß method has been developed.

abstract: Master of Engineering (ME)


title: A Laser Raman Spectroscopic Study of Iodine Cations

contributor:
Gillespie, R.J.
Chemistry

subject: Chemistry Chemistry

abstract:
I₂⁺Sb₂F₁₁⁻, a dark blue crystalline solid, was prepared by reaction of I₂ with SbF₅ using dried liquid SO₂ as solvent. The compound melts at 122°C and is moisture-sensitive. The presence of the I₂⁺ cation was established by laser Raman spectroscopy and by X-ray crystallography. The structure determination showed that the I₂⁺ cation has an I - I bond length of 2.557(4) Å.

The triatomic cations I₃⁺, IBr₂⁺ and ICI₂⁺ were produced in acidic solutions and their Raman spectra were obtained using specially designed spinning Raman cells. IBr₂⁺ and ICI₂⁺ were also prepared as the solid compounds IBr₂⁺SO₃F⁻ and ICI₂⁺SbCl₆⁻ and their Raman spectra were recorded. A simple valence force field treatment was applied to the Raman data for these three symmetric IX₂⁺ cations. Force constants were calculated and the bond angles of the bent structures were estimated.

The triatomic interhalogen cation I₂Cl⁺ was prepared by direct reaction of ICI and SbCl₅ to yield solid I₂Cl⁺SbCl₆⁻. By a similar halogen transfer process I₂Br⁺SbCl₅Br⁻ was prepared from IBr and SbCl₅. The Raman spectra of both of these dark-colored, low-melting solids were obtained using spinning cell techniques. Observation of Raman bands which could be assigned to a bending mode and to I - I and I - X stretching modes established that these two iodine-containing cations have an unsymmetric angular structure.

The existence of a new polyatomic cation Inⁿ⁺ containing iodine in a +1 oxidation state is proposed. This species has a strong Raman band at 195 cm⁻¹. The Raman evidence indicates that Inⁿ⁺ exists in H₂SO₄ and HSO₃F solutions and also in solid or molten ISO₃F.

abstract: Doctor of Philosophy (PhD)


title: Metal Vapors in Synthesis: The Chemistry of Chromium Sandwich Complexes

contributor:
McGlinchey, M.J.
Chemistry

subject: Chemistry Chemistry

abstract:
A series of substituted bis(fluorobenzene)chromium complexes, (C₆H₄FX)₂Cr, where X is ortho, meta and para H, F, Cl, CH₃ and CF₃, have been synthesized by cocondensing chromium atoms and fluoroarenes. The ¹⁹F n.m.r. chemical shifts of these compounds correlate well with those of the corresponding C₆F₅X system suggesting that the overall electron-withdrawing effect of a π-bonded chromium atom is similar to the effect of four ring fluorine substituents.

This correlation suggested that nucleophilic substitution reactions might be possible for fluorosubstituted bis(arene)chromium complexes; indeed bis(anisole) chromium was obtained in low yield from the reaction of bis{η-fluorobenzene)- chromium and sodium methoxide. Furthermore, a series of alkyl-and aryl-lithium reagents reacted readily with (C₆H₆)Cr(C₆F₆) at low temperature to yield polysubstituted products. Proton abstraction from the π-complexed C₆H₆ ring was a competing process and led to telomeric sandwich complexes of which several were identified spectroscopically.

The behaviour of these complexes was consistent with the view that the π-{C₆H₆)Cr moiety donated electron density to the C₆F₆ ring and, to investigate this further, a series of complexes (C₆H₆)Cr(C₆F₅X) was prepared via the lithium reagent (C₆H₆)Cr(C₆F₅Li). These data supported the view of the π-complexed C₆F₅X system being more electron rich than the free C₆F₅X rings.

These new sandwich complexes pose severe nomenclatural problems, and the CHROMARENE nomenclature has been proposed in an attempt to overcome these difficulties.

Preliminary studies with other metals, viz., iron and germanium have provided direct routes to ferrocenophanes and organogermenes respectively.

abstract: Doctor of Philosophy (PhD)


title: A Study of the Heavy Rhenium Isotopes

contributor:
Burke, D.G.
Physics

subject: Physics Physics

abstract: The structures of the transitional nuclei ¹⁸⁷Re , ¹⁸⁹Re and ¹⁹¹Re have been studied using the (t,α) proton pickup reaction. Beams of 15 MeV unpolarized tritons and 17 MeV polarized tritons were produced by the tandam Van de Graaff accelerator facility of the Los Alamos Scientific Laboratory. The reaction products were analyzed in a Q3D magnetic spectrometer and detected with a helical-cathode position-sensitive proportional counter. The unpolarized (t,α) reaction on thin targets of ¹⁸⁸,¹⁹⁰,¹⁹²Os produced spectra with energy resolutions of 8-12 keV (FWMH), from which level energies were accurately determined. Later, when the polarized-triton source became operational, the polarized (t,α) reaction on thicker osmium targets yielded angular distributions of analyzing powers and cross sections. Distorted-wave calculations were done to determine a set of optical model parameters which could reproduce the experimental results for known levels in ¹⁸⁷Re. The predictions of DWBA calculations were then used to assign spins and parities to other level in ¹⁸⁷Re, and to levels in ¹⁸⁹Re and ¹⁹¹Re. This is the first time the (t,α) reaction has been used to study deformed nuclei, and its usefulness for the purpose has been clearly demonstrated. The analyzing powers obtained were large, and their angular distributions were quite distinctive for different values of ℓ and j. This is also the first time level schemes have been assigned in the nuclei ¹⁸⁹Re and ¹⁹¹Re. The results have been interpreted within the framework of the Nilsson model, with corrections for pairing and Coriolis coupling included. The model has been found to provide a fairly good explanation for most of the experimental results. Some aspects of the data were better explained by including a hexadecapole component in the nuclear deformation. The hexadecapole deformation parameter winch gave the best agreement with the experimental results was ε₄ = 0.06 ± 0.01, which agrees well with theoretical predictions for nuclei in this mass region.

abstract: Doctor of Philosophy (PhD)


title: Antiferromagnetism in CsMnF₃

contributor:
Collins, M.F.
Physics

subject: Physics Physics

abstract:
Two of the magnetic properties of antiferromagnet, CsMnF₃, were studied by thermal neutron scattering techniques.

Spin wave-dispersion curves, along the two high symmetry directions (00ξ) and (ξ00), were determined and were satisfactorily fitted to a theoretical model with two nearest neighbour exchange constants, J₁₂ = 0.134±.003 THz and J₂₃ = 0.094±.0105 THz, and one second nearest neighbour exchange constant, J₃₅=-0.0138±.003 THz. The spin wave properties can be described in terms of an effective anisotropy field of -2700±900 Oe along the crystal c axis. This field constrains the spins to the basal plane of the crystal. The calculations show that magnetic dipole-dipole interactions, alone, provide enough anisotropy to account for the observed results.

The sublattice magnetization, over the temperature range of 6.8 K to 72.2 K, was measured. This shows a critical phase transition with a critical exponent β given by β = 0.317±.009.

abstract: Doctor of Philosophy (PhD)


title: Perturbations of semi-Fredholm operators in locally convex topological vector spaces

contributor:
Husain, T.
Mathematics

subject: Mathematics Mathematics

abstract:
It is a well-known result of I.C. Gohberg, M.G. Krein and T. Kato that if T is a semi-Fredholm operator between Banach spaces and P a bounded operator of norm small enough, or a compact operator, then T+P is a semi-Fredholm operator with the same index as T.

This thesis is concerned with extensions of this result to more general locally made of suitably defined small bounded or precompact perturbations or Φ₊ and Φ₋ -operators. The results obtained apply in particular to Frechet spaces and effectively extend the theorems of I.C. Gohberg, M.G. Krein and T. Kata as well as several or Ju.M. Vladimirski.

Duality is shown to be a convenient tool to prove many or these results. Some applications are also given.

abstract: Doctor of Philosophy (PhD)


title: Electron Transfer Reactions of Cytochromes c

contributor:
Morton, R.A.
Biology

subject: Biology Biology

abstract:
In the work described in this thesis we undertook studies of the electron transfer between cytochromes c and iron hexacyanides, a reaction which serves as a simple, well defined model for electron transfer in vivo. In particular, we were interested in the following aspects of electron transfer: the mechanism of the oxidation of ferrocytochrome c by ferricyanide, the mechanism of reduction of ferricytochrome c by ferrocyanide, the effect of charges on the protein and the ionic strength of the medium on electron transfer, and the effect of ions which bind to cytochrome c on oxidation and reduction. Since ion binding to cytochrome c has been observed by several techniques, cytochrome c preparations in this study were electrodialyzed, whenever possible, in order to remove contaminating bound ions.

The results of our work indicate that the oxidation of ferrocytochrome c by ferricyanide in nonbinding (tris-cacodylate) buffer follows irreversible second-order kinetics. The reduction of ferricytochrome by ferrocyanide was found consistent with the following reaction scheme:

[equation removed]

Our data suggests that there are different pathways for reduction and oxidation of cytochrome c when iron hexacyanides are used.

The effect of the ionic strength on the bimolecular rate for the oxidation of horse heart and P. aeruginosa ferrocytochromes in non-binding buffer was analyzed using Debye-Huckel theory, and suggested that the oxidation of horse heart ferrocytochrome c proceeds at nearly the diffusion-controlled rate. From this analysis an effective charge of +7.8 units for horse heart cytochrome c was obtained. The oxidation of P. aeruginosa cytochrome c was much slower and was not consistent with a diffusion-controlled reaction. The ionic strength dependence of the rate of oxidation for M. denitrificans ferrocytochrome c could not be fitted to Debye-auckel theory.

The ionic strength was also found to affect the reduction of ferricytochrome c by ferrocyanide. The measurements revealed that the dissociation constant Kd (= k₁/k₂) and the rate constant k₄ in the above mechanism are ionic strength dependent.

Analysis of the effect of binding ions on the rate of oxidation for horse heart ferrocytochrome c indicated that more than one chloride, phosphate, potassium and picrate ion were bound to horse heart ferrocytochrome c. The bound ion slowed the rate of oxidation.

The reduction of ferricytochrome c by ferrocyanide was approximated by a reversible second-order reaction, and the overall reduction and oxidation rates were derived. The ratios of these rate constants, measured in various buffers, were used to estimate the number of ions bound to ferricytochrome c and their respective binding constants. Approximately one chloride ion and almost two picrate ions were bound to horse heart ferricytochrome c. The rate of reduction of ferricytochrome c having bound ion(s) was also slower than normal.

Chemical modification (guanidination) of all the lysine residues of cytochrome c showed that positive charges and not lysines are necessary for efficient electron transfer between cytochrome c and iron hexacyanides.

abstract: Doctor of Philosophy (PhD)


title: Photochemical etching of n-InP

contributor:
Cassidy, D.T.
Kitai, A.H.
Materials Science and Engineering

abstract: The photochemical etching behaviour of n-InP was examined by producing holes or vias through the samples. The rate of material removal and quality of the resulting vias were studied as a function of: electrolyte pH, temperature, and type of metal ion impurity, illumination level, frequency, and duty cycle, sample surface quality, area, and roughness, and a second light source. The project was undertaken to prepare thin samples for the transmission electron microscope (TEM). The quality of sample produced for the TEM was acceptable, as determined by comparing the thin sections to thin sections produced by other traditional sample preparation techniques. This new method of sample preparation has the important advantages of being able to thin at a precisely predetermined region and that the resulting thin regions are surrounded by a thick built-in stabilizing structure which improves handleability.

abstract: Doctor of Philosophy (PhD)


title: Kinetics of trace metal interactions with lake sediments

contributor:
Kramer, James R.
Geochemistry

subject: Geochemistry Geochemistry

abstract: This study evaluates: (1) the use of a radiotracer technique to obtain kinetic data on trace metal interactions with sediments in a freshwater environment, and (2) the importance of kinetic considerations in trace metal partitioning between sediment and water in a lake. The technique consists of measuring the distribution of a small radiotracer spike between the sediment and the aqueous phase over time. The system is assumed to be at equilibrium prior to spiking. The radiotracer uptake by sediments is first determined, the aqueous phase is then replaced by a non-tracer solution, and finally the tracer release is measured. Preliminary studies with cadmium and zinc showed: (1) stable solution conditions (no tracer added) with negligible change in trace metal concentrations and master parameters (pH, DOC) over several weeks, (2) precision in replicate analysis and experiments, and (3) confirmation of the technique as demonstrated with a synthetic TiO₂ suspension. A novel experimental design was devised, consisting of a kinetic model fitting using the "adsorption" kinetic data, followed by confirmation comparing the model data to "desorption" kinetic data. The technique was applied to surficial samples from three lacustrine systems using ⁶⁵Zn and ¹⁰⁹Cd. The kinetics of metal exchange are very similar for all samples for both "adsorption" and "desorption". The general kinetic behaviour was a fast reaction (hours) followed by a slower interaction (weeks). Three kinetic models were investigated to explain the "adsorption-desorption" data. A two-box model (TBM), describes the system as a reversible solid-liquid first-order reaction. It does not, however, explain the slower exchange well. Two other models include two distinctive kinetic reactions. They differ mostly by the nature of the "desorption" reaction prediction. A "two-box model with a leak" (TBL) considers a fast reversible first-order reaction followed by a slower first-order reaction (leak). A "restricted three-box model" (RTB) considers two independent reactions, both first-order and reversible, but of different rates. The TBL and RTB models can be fitted to the "adsorption" data very well. The "desorption" data is, however, better predicted by the TBL model revealing the slower short-term (hours-days) interactions of trace metals with lake sediments. Trace metal partitioning determined by short-term (hours-days) interactions gives higher solution concentration than longer-term (weeks-months) "equilibrium" partitioning. Thus short-term prediction of metal partitioning based on long-term "equilibrium" distribution would overestimate the role of natural sediments as metal sinks. This kinetic approach gives good estimates of the uptake and release of trace metals between sediment and water in lacustrine systems.

abstract: Doctor of Philosophy (PhD)


title: Generative assembly process planning

contributor:
El, Hoda A.
Mechanical Engineering

abstract: The benefits of automating assembly sequence generation include: (1) insuring that no potentially good assembly sequence is overlooked, (2) reducing planning costs, (3) accelerating the analysis of the economical impact of different design solutions, (4) standardizing and improving the quality of the produced plans, and (5) contributing to achieving autonomous assembly systems. Previous research in assembly planning focussed on the generation and evaluation of all possible assembly plans for the product under consideration. This thesis presents a graph-theoretic approach for simultaneously generating and evaluating products' assembly/disassembly sequence alternatives and producing an optimum assembly plan according to predefined criteria. It aims at improving the efficiency of the assembly planning process and producing optimal assembly/disassembly plans. The developed graph-theoretic approach enables the determination of assembly sequences which transform any arbitrary initial state of the product into any arbitrary final state. Practically, this means many different types of assembly problems to be handled uniformly. A product is described in terms of its components and the assembly relationships between them. This description lends itself to a graph representation, where vertices correspond to the set C of assembly components and edges correspond to the set R of assembly relationships. For a product with "n" components, the generation of an assembly sequence is mapped into the problem of finding a sequence of "n-1" mutually exclusive cutsets in the graph model and its subgraphs. Each cutset corresponds to a disassembly operation of the physical product which produces two smaller subassemblies. Assembly sequences are encoded in a directed graph of assembly states, representing the search space. Geometric feasibility and accessibility constraints have been developed to help reduce this combinatorial search space. Assembly-related criteria which guide the search to an optimal solution are described. They are: (1) the number of re-orientations, (2) parallelism among assembly operations, (3) stability of subassemblies, and (4) clustering of similar assembly operations. Integrating the evaluation of these criteria as the search graph gets expanded, enables the direct generation of an optimal disassembly sequence of a given product with respect of these criteria. Standard search methods, including breadth first, depth first, best first, A* and hill climbing, are used to guide the search towards a single and optimal assembly sequence. The A* method can generate optimal solutions without explicitly generating the whole directed graph of assembly states. An interactive computer tool, based on the above approach, was developed. GAPP--a Generative Assembly Process Planner uses various search methods to incrementally construct the directed graph of assembly states and generate optimal assembly/disassembly sequences. Examples of real products are included to demonstrate GAPP's use and potential for assessing assembly, disassembly, repair, maintenance, assembly of multiple products and assembly error recovery procedures.

abstract: Doctor of Philosophy (PhD)


title: Biframes

contributor:
Banaschewski, Bernhard
Mathematics

subject: Mathematics Mathematics

abstract: Biframes and their homomorphisms are the subject of this thesis. Various traditional notions from topology and frame theory are extended to this setting: compactness, regularity, normality, zero-dimensionality, Booleanness, coherence, super-coherence, continuity, supercontinuity and connectedness. The category of biframes is shown to be complete and cocomplete, and its monomorphisms, epimorphisms and projectives characterized. Of particular importance are the compactifications--their correspondence with strong inclusions, the existence of zero-dimensional ones and of least ones, and their relations to rim-compactness and normality.

abstract: Doctor of Philosophy (PhD)


title: A Mechanism for Self Excitation in Hydraulic Control Devices

contributor:
Weaver, D. S.
Mechanical Engineering

abstract:
Researchers in recent years have attributed the dynamic instability of certain hydraulic control devices (such as gates, valves, and seals) to a velocity dependent hydrodynamic load which is equivalent to a negative damping coefficient in the differential equation of motion. Such a model is not capable of predicting certain important features of observed check valve behaviour.

A semi-empirical model for check valve self-excited vibrations is derived. The results show that the gross behaviour of this model is qualitatively the same as the experimental observations. Hence, the existence of a hydrodynamic load component in phase with displacement appears essential for the hydrodynamic load modelling.

A general mathematical model is then derived from first principles. Closure of the hydraulic control device during vibrations and unsteady flow phenomenon including viscous losses are taken into account. The proposed model can be applied to any type of hydraulic control device with a jet-flow mechanism of excitation. Two applications for the model have been examined. Check valve and seal applications show that the model results are in reasonable agreement with the experimental observations.

abstract: Master of Engineering (ME)


title: The application of partial least squares to problems in chemical engineering

contributor:
MacGregor, John F.
Marlin, Thomas E.
Chemical Engineering

abstract: The objectives of this work were to investigate the applicability of using Partial Least Squares (PLS) in three areas of chemical engineering: (1) for performance monitoring, (2) for inferential model development, and (3) in dynamic model identification. One further goal of this work was to gain understanding of the properties of the PLS method in the context of chemical engineering. Properties investigated included: (1) effects of scaling, (2) the objective function in the algorithm, and (3) the configuration of the X and Y data blocks. The first application of PLS was in the area of performance monitoring of a multivariate processes. A multivariate Statistical Process Control (SPC) procedure has been proposed for handling large numbers of process and quality variables. PLS is used to reduce the dimensionality of these large and highly correlated data sets down to a few latent variables which contain most of the information about the process behaviour under normal operating conditions. By compressing all the information on the process down to low dimensional spaces, and using simple plots of the data in these spaces, together with meaningful control limits, the essential idea and philosophy of Shewart's (1931) SPC methods have been preserved and extended to handle the large number of variables collected in most process industries today. PLS has also been shown to be a very powerful approach to inferential model building when large numbers of highly correlated measured variables are available. By retaining all the measurements without overfitting the data PLS is able to utilize all the information obtained from the process measurements. Further, PLS models are extremely robust to missing data and sensor failures, an important feature of any inferential control scheme. The importance of obtaining a representative reference data set, (i.e., one that represents the process relationships for the expected range of process conditions, and the structure of the process and control configuration under which the model is to be used), when using empirical models has also been demonstrated. The comparison of PLS, Ridge Regression (RR) and Least Squares identification of non-parsimonious (Finite Impulse Response (FIR) and Autoregressive exogeneous (ARX)) models for multiple input single output (MISO) systems shows that the biased estimates obtained from PLS and RR provide smoother estimates of the impulse and step weights. The difficulty in characterizing structured noise when using these non-parsimonious models is discussed. Finally, the use of PLS for identification of multiple input multiple output (MIMO) processes was investigated.

abstract: Doctor of Philosophy (PhD)


title: Patient-specific FDG dosimetry for adult males, adult females, and very low birth weight infants

contributor:
Nahmias, Claude
Medical Physics

abstract:
Fluorodeoxyglucose is the most commonly used radiopharmaceutical in Positron Emission Tomography, with applications in neurology, cardiology, and oncology. Despite its routine use worldwide, the radiation absorbed dose estimates from FDG have been based primarily on data obtained from two dogs studied in 1977 and 11 adults (most likely males) studied in 1982. In addition, the dose estimates calculated for FDG have been centered on the adult male, with little or no mention of variations in the dose estimates due to sex, age, height, weight, nationality, diet, or pathological condition.

Through an extensive investigation into the Medical Internal Radiation Dose schema for calculating absorbed doses, I have developed a simple patient-specific equation; this equation incorporates the parameters necessary for alterations to the mathematical values of the human model to produce an estimate more representative of the individual under consideration. I have used this method to determine the range of absorbed doses to FDG from the collection of a large quantity of biological data obtained in adult males, adult females, and very low birth weight infants. Therefore, a more accurate quantification of the dose to humans from FDG has been completed. My results show that per unit administered activity, the absorbed dose from FDG is higher for infants compared to adults, and the dose for adult women is higher than for adult men. Given an injected activity of approximately 3.7 MBq kg -1 , the doses for adult men, adult women, and full-term newborns would be on the order of 5.5, 7.1, and 2.8 mSv, respectively. These absorbed doses are comparable to the doses received from other nuclear medicine procedures.

abstract: Doctor of Science  (PhD)