identifier: Yadav, Arpita <https://research.library.mun.ca/view/creator_az/Yadav=3AArpita=3A=3A.html>   (1989) A study of AB initio computational techniques and their application to cis-trans photoisomerization of retinal analogs.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: Ab initio Hartree Fock self consistent field calculations are performed on retinal analogs using the STO-3G basis set.  Complete geometry optimizations are performed. The ground state properties (bond lengths, bond orders, net atomic charge distribution) of various cis and trans isomers of retinal analogs are studied in detail. Where necessary correlational effects are also taken into account by a simple model of strictly localized geminals. The effect of protonation on the properties of retinal Schiff base analogs  is studied Convergence in various properties is studied with  increasing chain length justifying the use of smaller analogs mimicking retinal. Convergence, is however slower for retinal protonated Schiff base analogs. The retinal protonated Schiff base analogs show an increased conjugation  in the vicinity of the NH₂⁺ group. The cyclohexene ring is shown to have little effect on bonding and other properties of the molecule, but causes local torsional distortions. Methyl groups also cause torsional distortions as they introduce steric hindrance. The potential energy surfaces for conformational change around the 6-s-bond and 12-s-bond are studied in detail. The introduction of a methyl group at C13 leads to a skewed geometry around C12-C13 and C10-C11 single bonds. The results indicate that for retinal PSB the preferred conformation is planar 11-cis, 12-s-trans as compared to 11-cis, skewed 12-s-cis in retinal. The introduction of methyl groups on the cyclohexene ring leads to two stable skewed 6-s-cis conformations, one at 58.5ﾟ above the plane and the other at 65.0ﾟ below the plane, plane being defined by C1-C6-C5-C4. Planar 6-s-trans conformation is predicted to be a transition state for the isolated chromophore. -- After a complete study of ground state properties, geometry relaxation studies are performed in the lowest lying triplet (³B) excited state utilizing RHF   and CHF methods. Since the UHF results suffer from significant spin contamination (even with the split valence 3-21G basis set), only the RHF results are considered. The RHF results on the other hand, lead into the methodological difficulties concerning the intrinsic RHF instabilities. The ³B excited state results are also discussed from the solid state physics point of view. The results suggest highly delocalized spin density in the vicinity of the NH₂⁺ group. π → π∙ excitation energies are calculated using 'Singlet-triplet Approximation' and all singles doubles configuration  interaction (SDCI) calculations, π → π∙ excitation energies are studied as a function of chain length and rotation around the single bond. A red shift in the lowest π → π∙ excitation energy is obtained on going from planar trans to planar cis conformation around a single bond or a double bond. Twisting around single bond leads to blue shift in accordance with the torsion model. SDCI calculations predict the lowest lying excited state to be ¹Ag-like corresponding to the forbidden transition from the ground state. -- Finally, based on ground and excited state results mechanisms for photocyclcs of rhodopsin, isorhodopsin and bacteriorhodopsin are discussed. Structural information on certain intermediates (bathorhodopsin, lumirhodopsin, metarhodopsin) is presented.


identifier: Jacob, Jayanthi <https://research.library.mun.ca/view/creator_az/Jacob=3AJayanthi=3A=3A.html>   (1990) An investigation of carbonyl insertion into M-CF3 bonds.  Masters thesis, Memorial University of Newfoundland.

type: Thesis NonPeerReviewed

format: application/pdf application/pdf

abstract: Carbonyl insertion continues to be of current interest as it  plays a vital role in many industrial preparations like hydroformylation, Reppe synthesis, Fischer-Tropsch process, etc. Carbonyl insertion has not been observed in M-CF₃ bonds  (M = transition metals) and the first report of apparent carbonyl insertion in a Fe-CF₃ bond stands in open conflict with both experimental and theoretical results. An investigation of the above report is presented in this thesis. -- Fe(CO)₃(diars) (diars = o-phenylenebis(dimethylarsine)) reacts with excess CF₃)I to form the perfluoroacyl Fe(CO)₂(diars)(C(O)CF₃)I and the per-fluoroalkyl Fe(CO)₂(diars)(CF₃)I compounds in varying yields, depending on the reaction conditions. A high concentration ratio of CF₃I to Fe(CO)₃(diars) favours the perfluoroalkyl while a dilute solution favours the perfluoroacyl compound. Concentration vs. time profiles of the reaction monitored by ¹⁹F NMR, indicate that the perfluoroalkyl and perfluoroacyl compounds are formed by two  independent reaction pathways. The perfluoroalkyl is formed by oxidative addition of CF₃I to Fe(CO)₃(diars) by a nonchain, free radical mechanism while the perfluoroacyl is formed by an intermolecular insertion mechanism via an ionic  intermediate. The higher analogues of CF₃I form only the perfluoroalkyl owing to the greater stability of the Rf radical which enhances the rate of the free radical reaction. -- Two isomers of the perfluoroalkyl compound were  isolated and spectroscopically identified by ¹H, ¹³C, ¹⁹F NMR, IR and Mass spectra as cis,cis and cis,trans isomers. Similarly, four isomers of the perfluoroacyl compound were isolated and identified. The structures of one perfluoroacyl  and one perfluoromethyl isomer were confirmed by single crystal X-ray data.


identifier: Mao, Huanyu <https://research.library.mun.ca/view/creator_az/Mao=3AHuanyu=3A=3A.html>   (1987) Analytical and kinetic investigations of the ferrous-ferric redox system in aqueous sulphuric acid with platinum electrodes.  Masters thesis, Memorial University of Newfoundland.

abstract: In process


identifier: Liang, Weimin <https://research.library.mun.ca/view/creator_az/Liang=3AWeimin=3A=3A.html>   (1994) Coordination chemistry of crown thiothers.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis describes the properties of thio-oxa crown ligands and their coordination chemistry. Chapter I briefly reviews the synthesis, conformation and coordination chemistry of crown thioethers. In Chapter II, synthesis and characterization of l-oxa-4,7-dithiacyclononane ([9]aneOS₂) and 1,10-dioxa-4,7,13,16-tetrathiacyclooctadecane ([18]aneO₂S₄) are reported. Molecular mechanics calculations are reported on [9]aneOS₂ and the molecular structure of [18]aneO₂S₄ has been determined by X-ray methods. In Chapter III, synthesis and properties of [Pd([9]aneOS₂)Cl₂] and [Pt([9]aneOS₂)Cl₂] have been described. Variable-temperature ¹H and ¹³C NMR studies reveal the unusual stereochemical non-rigidity in [Pd([9]aneOS₂)Cl₂], and the mechanism has been proposed. In Chapter IV and V, the structures of [Cu([9]ane0S₂)₂][ClO₄]CH₃CN and [Cu([9]aneOS₂)Br]₂ are presented together with their electrochemical properties. The results indicate that ligand [9]aneOS₂ considerably stabilizes Cu(I) over Cu(II). The synthesis and structure of  [Ag([18]aneO₂S₄)]ClO₄ are reported in Chapter VI.


identifier: Wu, Huikang <https://research.library.mun.ca/view/creator_az/Wu=3AHuikang=3A=3A.html>   (1992) Coordination chemistry of thioether ligands.  Masters thesis, Memorial University of Newfoundland.

abstract: A series of thiophene-containing thioethers (L1 = l,6-bis(2-thienyl)-2,5-dithiahexane; L2 = 1, 9-bis(2-thienyl)-2,5,8-trithianonane; L3 = 1, 9-bis(2-thienyl)-2,8-dithia-5-oxononane; L4 = 1, 7-bis(2-thienyl)-2,6-dithiaheptane) were prepared. Preparation of copper(II), copper(I), molybdenum (0), and tungsten(0) complexes with these ligands and L5 (L5= 2,5,7,10-tetrathia[12](2,5) thiophenophane) are described. The complexes were studied by nmr, esr, ir, electronic spectroscopy and by magnetic, X-ray structural and electrochemical methods. The structure and properties of  the copper complexes were studied in both the solid state and in solution and the structures were correlated with the spectroscopic characteristics. It has been shown that the structures of the copper-thioether complexes change when they dissolve and the extent of the change depends on the solvent and the solution concentrations. Variable temperature nmr studies have been used to examine the stereochemically non-rigid processes of molybdenum and tungsten carbonyl complexes of several of the ligands. At room temperature, all are undergoing rapid inversion of configuration at their metal-bound sulfurs by a solvent-independent process. No evidence of any 1,4-heteroatom fluxional processes was found at room temperature, but at elevated temperatures an unprecedented acyclic 1,4-heteroatom binding site fluxionality in Mo(CO)₄∙L2 has been observed. The molecular structures of CuCl₂∙2Ll, CuCl₂∙L3, CuBr∙L3, and W(CO)₄∙L5 have been determined by X-ray methods.


identifier: Golding, Peter David <https://research.library.mun.ca/view/creator_az/Golding=3APeter_David=3A=3A.html>   (1974) Isotope effects on chemical equilibria.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

title: Isotope effects on chemical equilibria

abstract: PART I -- The themodynamic equilibrium constants, Kt(H), of five monosubstituted acetic acids, RGH₂COOH, where R = Cl, Ph, PhO, PhS, and PhSO₂, have been measured conductimetrically. The syntheses of five isotopically substituted acetic acids, RCD₂-COOH, where R = Cl, PhO, PhS, PhSO, and PhS0₂, are described and the thermodynamic equilibrium constants, Kt(D), of three of these, R = Cl, PhO, and PhS, are reported. The calculation of secondary isotope effects of the second kind for the three isotopic acid pair's, RCH₂COOH/RCD₂COOH, where R = Cl, PhO, and PhS, has been accomplished by the appropriate comparison of thermodynamic equilibrium constants, Kt(H)/Kt(D), and by the  comparison of isotopic slopes, mt(D)mt(H). These slopes, mt(D) and mt(H), are derived from linear least squares treatments of the Classical and Shedlovsky conductance equations, and their comparison is demonstrated as a superior method in the calculation of isotope effects. -- A linear least squares interpolation to minimum deviation of Shedlovsky Kt values with variation of limiting equivalent conductance (Ao) is tested as a suitable method for the calculation of Ao. The effect of substituent variation on the isotope effects reported here disqualifies the simple inductive model as a legitimate description of secondary isotope effects of the second kind. The correlation of diminishing isotope effect per deuterium atom with increasing acidity is also invalidated by the present results. -- PART II -- The syntheses of 9-thia-9,10-dihydrophenanthrene-9-oxide and thioxanthene-10-oxide are described. These compounds have been partially deuterated at  their respective methylene positions by dissolution in alkaline deuterium oxide. Spectral evidence indicates stereoselectivity of the methylene protons in the exchange reactions of both compounds. Unlike phenylsulfinylacetic acid, interchange of the methylene proton chemical shifts does not occur for either compound when the solvent medium is varied from dimethyl sulfoxide-d₆ to trifluoroacetic acid. The proposed conformational change of thioxanthene-10-oxide from the pseudoequatorial array in chloroform-d to the  pseudoaxial array in trifluoroacetic acid is considered.


identifier: Qi, Zhigang <https://research.library.mun.ca/view/creator_az/Qi=3AZhigang=3A=3A.html>   (1992) Electrochemical studies on conducting polymers: copolymerization, ion transport, restructuring, overoxidation and reactivation.  Masters thesis, Memorial University of Newfoundland.

abstract: The electrochemical copolymerization of 1-methyl-3-(pyrrol-1-ylmethyl)pyridinium (MPMP⁺) with 3-methylthiophene (MeTh) has been accomplished from a wide compositional range of monomer solutions. An x-ray emission analysis method was developed to determine elemental composition and oxidation levels of such copolymers. A linear relationship was found to exist between the polymerization current density and the composition. The morphologies of the cationic copolymers were studied using scanning electron microscopy with the conclusion that surface roughness increases with increasing MeTh content and film thickness. Dual electrode and AC impedance measurements revealed that both the electronic and  ionic conductivities of the copolymers increased with increasing MeTh content. -- When poly(MeThx-MPMP⁺) was studied in aqueous Fe(CN)₆³⁻/⁴⁻, it was found that the anodic  to cathodic peak height ratios for Fe(CN)₆³⁻/⁴⁻ were about 1:1 and 0.75:1 at fast and slow scan rates, respectively. This difference was concluded to arise from the competition between HPO₄²⁻ and Fe(CN)₆³⁻/⁴⁻ during the redox process. HPO₄²⁻ is kinetically favoured, while Fe(CN)₆³⁻/⁴⁻ is thermodynamically favoured as the charge compensating counter ion in the copolymer. At fast scan rates, HPO₄²⁻ is the species that moves into and out of the copolymer to balance the excess charge during the redox process. At slow scan rates, Fe(CN)₆³⁻/⁴⁻ transport balances the excess charge during the redox process. It was also found that Fe(CN)₆³⁻/⁴⁻ in the copolymer could not be replaced by HPO₄²⁻ even in aqueous 0.1 M K₂HPO₄, and that cations such as K⁺ and Na⁺ were not involved in the ion transport process. -- Another finding was that the electrochemical response of a Fe(CN)₆³⁻/⁴⁻ saturated copolymer decreased with time. Since x-ray emission analysis revealed that the amount of Fe(CN)₆⁴⁻ in the film did not change during this decrease, it was realized that this decrease resulted from the formation of a  strong association between Fe(CN)₆⁴⁻ and the cationic sites in the copolymer. This association limits the mobility of Fe(CN)₆⁴⁻ ions, which in turn leads to a slower charge transport rate between Fe(CN)₆³⁻/⁴⁻ sites. The whole process has been termed restructuring of the copolymer film. The electrochemical activity of restructured copolymers could not be completely restored by C10₄⁻ exchange and resaturated  with Fe(CN)₆³⁻/⁴⁻. Restructured films retarded the reentry of Fe(CN)₆³⁻/⁴⁻ into the copolymer. -- Two methods to reactivate poly(3-methylthiophene) films overoxidized in Cl⁺ solution have been discovered. The first is an electrochemical method. The overoxidized polymer was reactivated in Et₄NClO₄/acetonitrile when the potential exceeded 0.9 V. The other method is to oxidize the overoxidized polymer with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The overoxidation process is proposed to occur through a nucleophilic addition between oxidized poly-MeTh and Cl⁺. The reactivation process is believed to involve further oxidation of the overoxidized polymer with the elimination of protons. Oxidation of poly-MeTh in Br⁻ and I⁻ solutions is also discussed.


identifier: Rice, Bernard Charles <https://research.library.mun.ca/view/creator_az/Rice=3ABernard_Charles=3A=3A.html>   (1984) Low frequency raman investigation of water and aqueous solutions.  Masters thesis, Memorial University of Newfoundland.

abstract: The Raman spectra of water and aqueous salt solutions are presented in the form of a vibrational density of states. R(ω). This R(ω) format reveals with greater definition the low frequency Raman bands due to polarizability changes in the weak bonds of intermolecular complexes. For pure water at 25ﾟC, broad bands were observed at 66 cm⁻¹ and 192 cm⁻¹ due to hydrogen bond bending and stretching modes. High signal to noise ratios achieved by multiple scans permitted the construction of difference spectra which greatly assisted the measurement of peak frequencies and depolarization data. The 192 cm⁻¹ band in the spectrum of water was found to be slightly polarized while the remainder  of spectrum exhibited largely depolarized features. The hydrogen bond stretching mode of water shifted 6 cm⁻¹ in D₂O and 17 cm⁻¹ in H₂¹⁸O. This mode is interpreted as arising from oxygens moving about the hydrogen involved in the hydrogen bond but with the proton remaining closer to one of  the oxygens. The effects of salts on the water spectrum have  also been investigated. Most salts increase the relative intensity of the water spectrum although typical structure breakers cause a decrease in the relative intensity. New bands have also been observed when salts are added to water.   Reorientation of the CO3²⁻ ion give rise to a depolarized scattering at 92 cm⁻¹ in aqueous solutions. Polarized bands due to cation and anion hydrates have also been observed. The symmetric stretch of the Mg(H₂O)₆²⁺ ion is observed at 359 cm⁻¹ in MgCl₂ while a polarized band for LICI(aq) occurs at 384 cm⁻¹. Polarized bands at 263 cm⁻¹ for saturated KF(aq). 298 cm⁻¹ for 10M NaOH(aq), 293 cm⁻¹ for 11.5M KOH(aq), 286 cm⁻¹ for 5.9M RbOH(aq) and in CsOH(aq) are assigned to stretching of the O-H∙∙∙X⁻ band.


identifier: Liu, Qingjun. 1962- <https://research.library.mun.ca/view/creator_az/Liu=3AQingjun=2E_1962-=3A=3A.html>   (1994) Lipid class and carbohydrate concentrations in marine colloids.  Masters thesis, Memorial University of Newfoundland.

abstract: Cross-flow filtration (CFF) was used to concentrate marine colloids from microalgal cultures and surface seawater. Lipid classes in different size fractions were determined using the Chromarod-Iatroscan thin-layer chromatography with  the flame ionization detection method. Total carbohydrate concentrations were determined colorimetrically using methyl  benzothiazolinone hydrazone reagent. Extensive determinations of CFF blanks and recoveries were conducted for each lipid class to optimize CFF operating procedures. The total lipid blank in the CFF system was approximately 6-7 μg (~0.5 μM C). Recoveries for the major lipid classes in marine samples varied from 80% to 120%. -- Both colloidal lipid and carbohydrate concentrations in microalgal cultures  were found to be 120-140 μg/L. Triacylglycerol (TAG) and polar lipids were the major lipid classes in colloids from microalgal cultures. Concentrations of colloidal (> 10,000 dalton) lipids and carbohydrates in Newfoundland seawater ranged from 0.9 μg/L to 8.7 μg/L and from 21 μg/L to 30 μg/L, respectively. The major lipid classes present in coastal seawater colloids were TAG, free fatty acids, and phospholipids. -- Data from both algal cultures and actual seawater samples showed that marine colloids are characterized by having high proportions of free fatty acids, phospholipids and hydrocarbons by comparison with truly dissolved material. The free fatty acids may be produced by microbial degradation, the phospholipids are probably derived from biological membranes, and the hydrocarbons are likely preferentially adsorbed from the surrounding water onto the colloids.


identifier: Dawson, Christopher John <https://research.library.mun.ca/view/creator_az/Dawson=3AChristopher_John=3A=3A.html>   (1973) Metabolites of some microorganisms.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

title: Metabolites of some microorganisms

abstract: In process


identifier: Zhao, Ziwei <https://research.library.mun.ca/view/creator_az/Zhao=3AZiwei=3A=3A.html>   (1993) Mechanistic studies of the electrodeposition of polythiophenes.  Masters thesis, Memorial University of Newfoundland.

abstract: The electrochemical deposition of poly(3-methylthiophene) and the electrochemical polymerization of 3-bromothiophene in the presence of 2,2'-bithiophene have been studied. Mechanisms have been proposed, based on the electrochemical responses recorded during polymer formation and characterization of the resulting polymer films by cyclic voltammetry, ac impedance spectroscopy, scanning electron microscopy as well as by x-ray emission spectroscopy. -- A rotating Pt disc electrode was applied to probe the potentiostatic deposition of poly(3-methylthiophene). It was  observed that poly(3-methylthiophene) films could be formed on both stationary and rotating electrodes even at rotation rates as high as 1600 rpm (revolutions per minute), and that the quantity of polymer deposited decreased with increasing rotation rate. It was therefore concluded that polymer deposition takes place both through the precipitation of oligomeric intermediates from the solution, and via the coupling of monomeric species with polymer chain ends in the  polymer film matrix. Chronoamperometric responses recorded during polymerization, as well as the characterization of the resulting polymer films by cyclic voltammetry, ac impedance spectroscopy and scanning electron microscopy, demonstrated that the deposition of oligomeric intermediates  from the solution contributes most to polymer formation on a  stationary electrode. On the other hand, polymer growth on a  rapidly rotating electrode occurs primarily by the incorporation of monomeric species into polymer chains grafted on the electrode surface. Much smoother, more homogeneous films were deposited on rotating electrodes. -- The polymerization of 3-bromothiophene in the presence of 2,2'-bithiophene was investigated by cyclic voltammetry. With a catalytic amount of 2,2'-bithiophene, a significant increase in the polymerization rate, together with a decrease in the potential required for poly(3-bromothiophene) formation, was observed. The polymer coated electrodes from the mixed solution exhibited characteristic electrochemical behaviour in cyclic voltammograms and Br and S peaks in x-ray emission spectroscopy for pure poly(3-bromothiophene). The 2,2'-bithiophene catalyst produces better quality poly(3-bromothiophene) films. A polymerization mechanism involving radical-monomer coupling is supported by these experimental observations. In this mechanism, the 2,2'-bithiophene catalyst is oxidized first, and then couples with 3-bromothiophene to initiate the polymerization.


identifier: Wellman, Mark A. <https://research.library.mun.ca/view/creator_az/Wellman=3AMark_A=2E=3A=3A.html>   (1996) Facial selectivity in the Diels-Alder reaction of plane-nonsymmetric cyclopentadiene derivatives.  Masters thesis, Memorial University of Newfoundland.

abstract: π-Facial selectivity in the Diels-Alder reaction of 1,3-cyclopentadienes substituted at C-5 with various halogens (C1, Br, I) and alkyl groups (Me, Et, π-Bu, CH₂OCH₃) is detailed. It was found that N-phenylmaleimide, 4-phenyl-1,2,4-triazoline-3,5-dione and tetra- cyanoethylene gave markedly different diastereofacial outcomes with a given diene thus proving that the nature of the dienophile as well  as the C-5 substituent on the diene imparts a significant influence on the reaction. -- The results obtained were investigated by collaborators using high level 6-31G* theoretical calculations. The mechanism of facial selectivity is explained on the basis of a steric interaction between the diene and the dienophile that induces bending mainly in the diene. This bending translates  into torsional strain in the diene in its syn transition state and the amount of distortion that occurs determines the diastereofacial outcome of the reaction. It was also found that the dienophiles studied imparted different steric  effects on the substituted dienes thereby each affording different facial outcomes with a given diene. These results also disprove many popular theories that have recently been proposed involving the mechanism of π-facial selectivity in Diels-Alder reactions.


identifier: Yang, Zheng <https://research.library.mun.ca/view/creator_az/Yang=3AZheng=3A=3A.html>   (1995) Development of a gas chromatographic method for profiling neutral lipids in marine samples.  Masters thesis, Memorial University of Newfoundland.

abstract: Profiling neutral lipids is one of more difficult applications of gas chromatography (GC), but it can contribute important information on unrevealed neutral lipid  suites in their entirety from marine environments. Thin layer chromatography with flame ionization detection (TLC-FID) is extensively used today but has many inherent limitations. In this study, a high temperature GC lipid profiling method was optimized for use with neutral lipids in highly unsaturated samples from a subpolar marine environment. Chemometrics was employed to optimize autoinjection procedures and column temperature programs. Other components in the GC, including the selection of carrier gas types, injection techniques, length of the column, septum types and retention gap, were investigated. A  hydrogenation step was required to avoid discrimination of the FID responses in highly unsaturated samples. Analyses of  fatty acids, moieties of the neutral lipids, supported the neutral lipid profile data. The identification of major sterols was confirmed by GC coupled to mass spectrometry (GC-MS). Summed molecular species from each neutral lipid class determined gas chromatographically were linearly correlated with neutral lipid subclasses determined by Chromarod TLC-FID. The developed method was applied to a range of marine samples, including algae, bivalves, polychaetes, fish eggs and fish larvae, revealing for the first time, neutral lipid carbon number distributions in marine species from cold oceans.


identifier: Kelly, John Francis <https://research.library.mun.ca/view/creator_az/Kelly=3AJohn_Francis=3A=3A.html>   (1992) Development of a quantitative method for the analysis of neutral saccharides in wood pulp using analytical pyrolysis.  Masters thesis, Memorial University of Newfoundland.

abstract: Traditional methods for the determination of the neutral saccharide composition of complex biomaterials such as wood pulp are difficult and time-consuming.  By comparison analytical pyrolysis techniques offer the advantages of speed and simplicity.  Under the appropriate conditions, pyrolysis yields products that retain the stereoconfiguration of the parent neutral saccharide (the anhydrosugars).  The objective of this investigation was to develop a method to quantitate the neutral saccharides in wood pulp using on-line pyrolysis - gas chromatography (Py-GC).  Initial efforts focussed on maximizing the yields of anhydrosugars from isolated polysaccharides resembling those found in wood.  Factors such as pyrolysis temperature and cation-exchange were investigated.  Next, a variety of wood pulps of differing composition and origin were investigated by Py-GC.  The numerous pyrolyzates produced by these pulps were characterized by Py-GC-MS using both electron impact (EI) and chemical ionisation (CI).  Finally, Py-GC methods were developed to quantify the saccharide compositions of the pulps.  Comparisons were made with results obtained by acid hydrolysis - derivatization /gas chromatography.  Two on-line pyrolyzers, the CDS Pyroprobe 120® and the SGE Pyrojector®, were compared as to their suitability for quantitative analysis.


identifier: Hillier, Judith Margaret <https://research.library.mun.ca/view/creator_az/Hillier=3AJudith_Margaret=3A=3A.html>   (1975) A study of the indicator pigment isolated from the slime mould Physarum Flavicomum.  Masters thesis, Memorial University of Newfoundland.

abstract: The slime mould Physarum flavicomum exhibits synchronous nuclear divisions and has been widely used to study the biochemical changes which take place on differentiation. One example of this, sporulation, has been shown to require light and the plasmodial pigments have been implicated as possible photocatalysts or photoreceptors. In order to fully understand this process it is necessary to know the chemical structure of the pigments. One pigment shows changes in absorption maxima with variations in the pH of the solution and has been called the “indicator” pigment. It is with this pigment that the present investigation is concerned. -- The pigment was isolated and purified using a modification of the method employed Khalil. Elemental analyses gave empirical formulae of C₁₂.₁H₁₃.₁O₅N for the protonated pigment and C₁₁.₂H₁₆.₅O₇.₂N Na and C₁₂.₃H₁₃.₉O₇.₇N Na₂.₅ for the sodium salt of the pigment. The n.m.r. spectrum agrees with a high degree of unsaturation in the pigment molecule. -- The presence of the tetraene, identified by Khalil, was confirmed by oxidation experiments. Hydrolysis indicated the presence of a carbohydrate, possibly sorbose, and basic compounds which were isolated, by several methods, as their hydrochlorides, but were not identified. -- Pigment isolated from frozen plasmodia had a molecular mass of approximately 1880, determined by oxidation techniques, and a low E1%/1cm value of 200. This pigment yielded five amino acids on hydrolysis, two of which were tentatively identified as glycine and alanine. There was also evidence, on hydrolysis, of an amino sugar which was possibly glucosamine. It is suggested that this pigment contains a peptide. -- Khalil proposed a tetraene conjugated to a 2,4-pyranone system to be the chromophore of the pigment. In order to investigate this possibility, compounds were synthesized by reacting triacetic acid lactone at the 3 and 6α positions. On of the products, 4-hydroxy-6-(4-(2-furyl)buta-2,4-dienyl)-2H-pyran-2-one, had the same absorption maximum as the pigment but the hyperchromic, bathochromic shifts it displayed on acidification were not as great as those shown by the pigment. However, it does represent the best model system for the pigment available at the present time.


identifier: Naperstkow, Arvin Mark <https://research.library.mun.ca/view/creator_az/Naperstkow=3AArvin_Mark=3A=3A.html>   (1990) A) [Pi]-facial diastereoselectivity in Diels-Alder reactions of 2,5-dimethylthiophene oxide and related compounds ; B) A synthetic approach to a chiral ketene equivalent.  Masters thesis, Memorial University of Newfoundland.

abstract: The reactivity and diastereofacial selectivity of some thiophene oxides particularly 2,5-dimethylthiophene oxide in  Diels-Alder reactions are reported. The sulphoxides were generated "in situ" by peracid oxidation (m-chloroperoxybenzoic acid). In all successful cases of cycloaddition, the dienophiles benzoquinone, naphthoquinone,  tetracyanoethylene, N-phenylmaleimide and 2-chloroacrylonitrile afforded exclusively the syn adduct with  respect to the sulphoxide oxygen. The structures were confirmed by X-ray crystallographic analysis. -- This facial  preference is consistent with the relative donor ability of the lone pair versus the sulphoxide oxygen. In accord with the concept of transition state stabilization by ϭ electron donation into the vacant ϭ†∙ orbital, associated with the incipient bond, addition should occur anti to the better donor, (i.e.) the lone pair, as observed. Thiophene oxides thus represent latent butadiene equivalents that react with complete facial control. -- The second and third parts of this thesis describe unsuccessful synthetic studies directed  toward intramolecular thiophene oxide cycloadditions and the  preparation of a sulphoxide based ketene equivalent.


identifier: Zhu, Yanyi <https://research.library.mun.ca/view/creator_az/Zhu=3AYanyi=3A=3A.html>   (1993) A synthetic study of some triquinane natural products and microbial reduction of prochiral spirodiketones.  Masters thesis, Memorial University of Newfoundland.

abstract: The first half of this thesis describes an approach to the synthesis of a group of triquinane sesquiterpenes, with (±) deoxypentalenic acid as the particular target. The synthesis  started from readily available isophorone. The central quaternary center of the natural product was established in an early step by a double acylation reaction on a cyclohexene derivative. Cleavage of the double bond was followed by reclosure to a five-membered ring. The relative stereochemistry at a stereogenic methine was controlled by catalytic hydrogenation. An intramolecular aldol reaction was used to cyclize the third ring of the triquinane moiety.  The remaining steps to (±)-deoxypentalenic acid were modeled  in reactions leading to β-keto esters and in reductions of the ketone moiety of a β-keto ester. -- The second part of the thesis provides the results of chiral reductions of 1,3-cyclopentanedione derivatives using baker's yeast. The series of diketones that was examined included 7,9,9-trimethylspiro[4.5|dec-7-ene-1,4-dione. The yeast reduction of this compound to (4S,5R)-4-hydroxy-7,9,9-trimethylspiro[4.5]dec-7-en-l-one (123) proceeded with high facial selectivity and enantioselectivity, as determined by an analysis of the corresponding Mosher's ester [(+)-α-methoxy-α-trifluoromethylphenyl-acetate derivative]. The facial selectivity was compared with that of the chemical  reduction using sodium borohydride. The absolute stereochemistry was established from CD spectra and an X-ray  structure. The transformation of compound 123 into (4R,5S)-4-hydroxy-4,7,9,9-tetramethylspiro[4.5]dec-7-en-l-one, an optically active form of an intermediate in the triquinane synthesis, required four steps.


identifier: Walters, Robin V. <https://research.library.mun.ca/view/creator_az/Walters=3ARobin_V=2E=3A=3A.html>   (1989) Investigation of the phase transitions in the alkali metal nitrites using Raman spectroscopy.  Masters thesis, Memorial University of Newfoundland.

abstract: The alkali metal nitrites have been studied from 77 K through the phase transitions and in the molten state by Raman spectroscopy. With the exception of LiNO₂, all the alkali metal nitrites go through at least one solid-solid phase transition. The presence of NO₂ groups disordered over  non-equivalent crystallographic sites is a common feature of  at least one phase for each salt. -- The results for LiNO₂ are not consistent with the suggested D⁵₃d crystal structure. Spectroscopic evidence and ab initio calculations  indicated that the NaNO₂ order-disorder transition occurs via a nitrite rotation about the crystallographic a axis. No  evidence was obtained for the reported phase transitions at 343 or 380 K in KNO₂ or for the high temperature phase transition in CsNO₂. For RbNO₂, the effect of nitrate impurity was considered. The spectroscopic observables are discussed in relation to available thermodynamic quantities.


identifier: Winter, J. (nee Martin) <https://research.library.mun.ca/view/creator_az/Winter=3AJ=2E_=28nee_Martin=29=3A=3A.html>   (1968) Solvolysis of esters of trifluoracetic acid.  Masters thesis, Memorial University of Newfoundland.

abstract: Although the spontaneous hydrolysis of simple alkyl esters related to halogenoacetic acids has frequently been studied, no systematic body of rate data is presently available concerning the reactivity of these substances in light and heavy water. The purpose of the present study is to survey the temperature dependence of the rates of hydrolysis in water and deuterium oxide of four esters derived from triflouoracetic acid (CF₃COOR: R = methyl, ethyl, i-propyl and tertiary butyl). -- On the basis of ¹⁸O tracer Bunton and Hadwick (1) have concluded that the spontaneous hydrolysis of methyl trifluoroacetate in pure water takes place by acyl-oxygen fission (B Ac² mechanism). On the other hand, Moffat and Hunt (2) have concluded that tertiary butyl trifluoroacetate reacts by an SN1 mechanism in acetone-water mixtures. These observations suggest that a change in mechanism (B Ac² → SN1) is to be expected in the hydrolysis of the series of trifluoroacetates mentioned above. The aim of this work is to attempt to locate the region of mechanistic change by using the thermodynamic parameters characteristic of the activation process (ΔG⁺, ΔH⁺, ΔS⁺, and ΔC⁺p) as well as the ratio of the rates of hydrolysis of each substrate in light and heavy water. An attempt has also been made to assess the significance of the parameter, ΔC⁺p, in cases where a reaction is occurring by more than one mechanism.


identifier: Pi, Zulan <https://research.library.mun.ca/view/creator_az/Pi=3AZulan=3A=3A.html>   (1996) New electron deficient dienes and their normal and inverse electron demand Diels-Alder reactions.  Masters thesis, Memorial University of Newfoundland.

abstract: 1.3-Butadienes bearing electron donating groups at their 1 and 3 positions (e.g. Danishefsky's diene 50) are popular dienes for the normal Diels-Alder reaction due to their regiochemically predictable cycloaddition with a variety of electron deficient dienophiles and the multifunctional adducts they provide.  However, their counterparts which bear electron withdrawing groups at their 1 and 3 positions, and their inverse electron demand Diels-Alder reactions are uncommon.  Due to the instability of the few known parent dienes, e.g. dienes 56a-d and 59, the cycloalkane-annulated diene system 63d was chosen for initial study. -- The protected dienes (68, 70, 72) and the deprotected dienes (69, 71, 73) were prepared from the commercially available 2-cyclohexen-1-one in four and five steps, respectively.  All these dienes were obtained as pure 2E isomers except 72, which was obtained as a mixture of 2E and 2Z isomers (72a and 72b).  The synthetic methodology was also employed to prepare dienes such as 83-86, which feature a five-membered ring. -- The protected dienes 68 and 72 underwent cycloaddition with electron deficient dienophiles (TCNE, PTAD, DMAD, NPM, MA, NQ and BQ) to give endo adducts as the major products.  The structures of the adducts 100,103,106,110, 113 and 114 were determined by X-ray crystal structure analysis whereas the structures of other adducts were assigned by analogy.  Epimerization was observed in the reactions of 68 with TCNE and with DMAD.  Treatment of the protected diene 68 with an electron rich dienophile, 1,1-diethoxyethylene, in refluxing toluene resulted in no reaction. -- The deprotected dienes 69, 71 and 73 participated in cycloaddition with the electron rich dienophiles ethyl vinyl ether, 1,1-diethoxyethylene, 1-ethoxy-1-(trimethylsilyloxy)ethylene and styrene.  Nothing less than 100% regioselectivity was ever observed.  The resulting adducts incorporated a variety of functionality and offer the potential to be elaborated in a number of ways. -- Dienes 69 and 71 reacted with ethyl vinyl ether with 100% regioselectivity to give the endo adducts 118a and 122.  Epimerization of 118a to give 118c was observed during chromatography. -- The reactions of dienes 69 and 71 with 1.1-diethoxyethylene occurred with complete regioselectivity and in 81-86% yield.  The structure of the adduct 123a was assigned by X-ray crystallography.  Reaction of 73 and the same dienophile resulted the formation of a new diene 125 by the elimination ethanol from the initially formed adduct. -- Diene 69 underwent cycloaddition with styrene to provide the endo adduct 127 as the major product, as determined by X-ray crystallography.  The minor product was assigned as the exo adduct 128 by comparing its nmr spectra with those of other adducts. -- Dienes 69 and 73 reacted with enamines to give the aromatized compounds 132 and 138 by elimination of an amine from the initially formed adducts and subsequent dehydrogenation.  Both 69 and 79 underwent cycloaddition with PTAD to give crystalline adducts 141 and 143.  Epimerization was observed during chromatographic purification of these adducts to give a mixture of them and their epimers 142 and 144.  Reaction of 69 with NPM followed by chromatography resulted in one major product in 90% yield, but a conclusive structural assignment of the adduct has not been made.


identifier: Copp, Steven B. <https://research.library.mun.ca/view/creator_az/Copp=3ASteven_B=2E=3A=3A.html>   (1995) New heterocycles with hydrocarbon cage substituents.  Masters thesis, Memorial University of Newfoundland.

abstract: The proficiency with which main group (n≥3) π systems (e.g. the nitrile sulphides (C≡N⁺-S') and phosphaalkynes (C≡P)) imitate organic chemistry has been well documented. An investigation of the ability of main group π systems to be stabilized by mono- and di-substituted hydrocarbon cages (adamantane, bicyclo[2.2.2]octane) was undertaken. These types of compounds have not been extensively reported in the  literature. Adamantyl-1,3,4-oxathiazol-2-one and bis-(3-Mesityl-1,2,4-oxazaphosphole)bicyclo [2.2.2]octane, have been prepared for the first time. The first X-Ray crystal structures of the oxathiazolone and oxazaphosphole heterocyclic rings will also be reported. The synthesis of precursors to these compounds will be presented along with full spectral characterisation. Attempts to generate a molecule containing two independent phosphaalkyne moieties will also be discussed.


identifier: Griffiths, Stephen John <https://research.library.mun.ca/view/creator_az/Griffiths=3AStephen_John=3A=3A.html>   (1974) Studies in aromatic reactivity.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

title: Studies in aromatic reactivity

abstract: The half-wave potentials of six series of Schiff basese each  of nineteen compounds, of the types ArCH=NAr' and ArN=CHAr',  where Ar represents an unsubstituted aryl group and Ar' represents a phenyl group substituted in the meta or para positions, have been measured in dimethylformamide, using a mercury pool reference electrode. The effects on the half-wave potentials of changing the substituent in Ar' and of varying the structure of Ar have been investigated. Substituent effects have been examined in terms of the Hammett ϭ-ρ relationship and also in terms of a substituent constant, ϭSB, generated from the data of the Schiff bases (Series B) having the general formula C₆H₅CH=NC₆H₄X. Structural variations in Ar have been studied by adopting Series B as the standard Schiff base series and by generating substituent constants for each structure. -- The values of the reaction constant, ρ, obtained in the present study range from 10.06 to 23.23 and are much larger than ρ values usually obtained in solution. These values are similar in magnitude to ρ values obtained in gas phase reactions. This suggests, in the polarographic reduction of Schiff bases in dimethylformamide, that solvent effects are virtually absent. -- Variations in the half-wave potentials with structure of Ar for the unsubstituted aldehyde fragment  of tne molecules have been correlated with quantities derived from the perturbed molecular orbital version of the Huckel molecular orbital theory. Correlations between series  of Schiff bases of the type ArCH=NAr' (Ar=C₆H₅, 2-naphthyl, 9-phenanthryl, 9-anthryl) and a' correlation between two series of the type ArN=CHAr' (Ar-C₆H₅, 2-naphthyl) have also been obtained as predicted previously.


identifier: Ogbomo, Sunny M. <https://research.library.mun.ca/view/creator_az/Ogbomo=3ASunny_M=2E=3A=3A.html>   (1995) π-Facial diastereoselectivity in the Diels-Alder reactions of substituted cyclohexadienes.  Masters thesis, Memorial University of Newfoundland.

abstract: The Diels-Alder reaction of cis-cyclohexa-3,5-diene-1,2-diol  derivatives 50, 51, 40a, 41a and 42a with diethyl azodicarboxylate (DEAD) gave very predominantly products 56,  58, 59, 60 and 62, which arose by addition to the oxygen functions. -- Similarly, cis-cyclohexa-3,5-diene-1,2-diol derivatives 50, 51, 40a, 41a, 42a, and benzene oxide-oxepin 48 reacted with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) 109 to afford anti adducts 70, 68, 70, 71 and 69 exclusively, and the anti adduct 66 was the predominant product in the case of diene 50. Moreover, there was a reversal of selectivity when the cis-diol 49 reacted with PTAD, the predominant product 64 arose by addition syn to the oxygen function. The structures of the adducts were determined by nmr, and X-ray crystallography in the cases of  72, 67, and 64. While the anti selectivity was rationalized in terms of electronic effects, hydrogen bonding explained the syn selectivity obtained with diene 49. -- The acetonide  40a and its Diels-Alder reaction with dienophiles are described. The experiments indicated that the acetonide dimerized in a Diels-Alder manner affording two products in a ratio of 6:1. The major dimer was that in which addition occurred to the anti face of both reacting partners. -- The results of Diels-Alder reactions of acetonide 40a with PTAD, DEAD, dimethyl acethylenedicarboxylate (DMAD), tetracyanoethylene (TCNE) and ethyl propiolate (EP) afforded  exclusively anti products 69, 59, 73, 81 and 86, respectively. When butenone, benzoquinone, maleimide and N-methylmaleimide were used, the predominant products were anti adducts, but selectivity was in favor of syn with vinylene carbonate and there was no selectivity when dimethyl maleate was used. Lone pair-lone pair i.e. electronic factor is invoked to explain these selectivities,  an alternative rationalization is in terms of electron-donating and electron-withdrawing effects. -- A study of the  influence of solvent on facial selectivity was carried out using the acetonide 40a with maleimide. The kinetic results indicated that there was significant facial selectivity when  water or a polar solvent was used but selectivity was less in a non-polar solvent. A 1M solution of LiCI in 100 mL water gave higher selectivity than a 5M solution of LiCIO₄ in ether. However, selectivity was with LiCIO₄ in water. Solubility and concentration phenomena are used to rationalize these selectivities.


identifier: Gillard, James R. <https://research.library.mun.ca/view/creator_az/Gillard=3AJames_R=2E=3A=3A.html>   (1992) π-Facial selectivity in the Diels-Alder reactions of the 1,3-cyclohexadienes bearing allylic oxygen substitution.  Masters thesis, Memorial University of Newfoundland.

abstract: The Diels-Alder reaction of cis-3,5-cyclohexadiene-1,2-diol (121) and a number of its acyclic derivatives, cis-1,2-diacetoxy-3,5-cyclohexadiene (109), cis-1,2-bis- (trimethylsiloxy)-3I5-cyclohexadiene(122)andcis-1,2-dimethoxy-3l5-cyclohexadiene(124) were found to add N-phenylmaleimide in a kinetically controlled manner to yield adducts that arose mainly by attachment of the dienophile to the face of the diene syn to the oxygen atoms. Some cyclic derivatives of 121, cis-3a,7a-dihydro-2,2-dimethyl -1,3- benzodioxole (114) ,cis-3a,7a-dihydro-2,2-dimethyl-1,3,2-ben2odioxasilole (123) and cis-2- ethyl-3a,7a-dihydro-2,1,3-benzoboradioxoie (125), afforded nearly equal quantities of both syn and anti adducts. Benzylidene-protected derivatives (2α,3aβ,7aβ)-3a,7a-dihydro-2- phenyl-1,3-benzodioxole (132) and (2α,3aα,7aβ)-3a,7a-dihydro-2-phenyl-1,3-benzodioxole (133) also reacted with N-phenylmaleimide, but they gave predominantly anti-addition products. -- 1,3,5-Cyclohexatriene-1,2-oxide (142) and its more substituted derivatives, 1,2- dimethyl-1,3,5-cyclohexatriene-1,2-oxide (148a) and 10-oxatricyclo[4.3.1.0]deca-2,4- diene (148b) reacted also with N-phenylmaleimide to give only products that resulted from addition of the addends to the face of the diene anti to the epoxide oxygen. -- The results obtained have been discussed in the context of the many theories that attempt to define the controlling factors involved in determining (syn/anti) π-facial selectivity of plane-nonsymmetric dienes bearing an allylic heteroatom. Steric effects and stereoelectronic effects are invoked in this study to rationalize the results we report here. In particular, our contrasting results with the diol-derived dienes and the benzene oxides are consistent with syn-addition being determined by the presence of a favorable secondary orbital interaction between the LUMO of the dienophile and the components of the highest occupied molecular orbitals that reside on the allylic oxygens of the dienes.


identifier: Zhang, Yisheng <https://research.library.mun.ca/view/creator_az/Zhang=3AYisheng=3A=3A.html>   (1993) Polynuclear coordination complexes of some polyisoindolines and polyphthalazines.  Masters thesis, Memorial University of Newfoundland.

abstract: In an attempt to enhance the bulk extended magnetic properties of antiferromagnetically coupled Cu(II) complexes a series of tetranuclear, hexanuclear and octanuclear Cu(Il) coordination complexes of some dendritic polyphthalazine ligands was synthesized and studied. The ligands were obtained by reacting various polyalcohols with 4-nitro-1,2-dicyano-benzene to produce a series of polyphthalonitriles, then condensing with 2-aminopyridine to produce the polyisoindoline intermediates and finally ring expanding with aqueous hydrazine to form the polyphthalazines. Dinuclear complexes were also obtained by reacting two dinucleating polyisoindolines with Cu(II) salts. Analytical spectral, X-ray, and magnetic studies on the complexes reveal that the polyphthalazine ligands are able to bind two pairs, three pairs and four pairs of metal ions in triple bridged, spin-coupled dinuclear centers, one on each branch of the extended polyphthalazine ligands. Two tetranuclear Cu(II) nitrate complexes, [Cu₄(C-P)(μ₂-OH)₂(μ2-NO₃)₂(NO₃)₂(H₂O)₂](NO₃)₂4H₂O and [Cu₄(O-P)(μ₂-OH)₂(μ₂-NO₃)₂(NO₃)₂(H₂O)₂] (NO₃)₂10H₂O, of the tetranucleating polyphthalazines (O-P, C-P) have been characterized by single crystal X-ray diffraction. In these dinuclear centres two, five or six-coordinate Cu(II) ions are brought into close proximity and bridged by the phthalazine diazine (N₂) and hydroxide groups equatorially and by a bidentate nitrate group axially. The overall structure of the tetranuclear Cu(II) complex of O-P reveals that the Cu4 complexes are connected through bridging bidentate nitrates and hydrogen bonding interactions, forming a zig-zag, nanometre scaled, molecular tube with hydrophilic groups inside and hydrophobic groups outside. Variable-temperature magnetic susceptibility measurements on some complexes indicate that strong anti ferromagnetic couplings exist within each dinuclear centre, but across the ligand framework coupling is very weak. These polynuclear Cu(II) complexes usually exhibit cyclic voltammograms at positive potentials (V vs SSCE) associated with Cu(II)->Cu(I) reduction. -- Preliminary studies have also been carried out on the synthesis of a 'star-like' lithium phthalocyanine peripherally substituted with isoindoline and phthalazine groups in an attempt to generate a system with spin coupled centres linked to a macrocyclic core with extensive π conjugation.


identifier: Ren, Yi <https://research.library.mun.ca/view/creator_az/Ren=3AYi=3A=3A.html>   (1992) Synthesis of 1α, 5α-cyclosteroids.  Masters thesis, Memorial University of Newfoundland.

title: Synthesis of 1α, 5α-cyclosteroids

abstract: Epoxidation of 4,4-dimethylcholesta-1,5-dien-3-one with m-chloroperbenzoic acid gave a mixture of the epimeric 5α, 6α-epoxy- and 5β, 6β-epoxy-4,4-dimethylcholest-1-en-3-one. Unexpectedly, the major product was found to be the 5β, 6β-epoxide, in contradiction to what had been reported by others. The unambiguous assignment of the structures of these epoxides was based upon ¹H NMR experiments and X-ray crystallographic analysis of the 5α, 6α-epoxide. In this thesis, the chemistry of the 5β, 6β-epoxide is described in the context of attempts at the synthesis of the corresponding 1α, 5α-cyclosteroids.  -- The synthesis of a new 1α, 5α-cyclosteroid, 4, 4-dimethyl- 1α, 5α-cyclocholesta-3,7-dione, by lithium or ytterbium in liquid ammonia reduction of the bis-α, β-unsaturated ketone 4, 4-dimethylcholesta-1,5-diene-3,7-dione, is described. The chemistry of the reductive cyclization is discussed. The ¹H- NMR spectra of the mono- and dihydroxy derivatives of the 1α, 5α-cyclosteroid reveal an unusually high-field signal due to H-9. X-ray diffraction analysis of 7β-hydroxy-4, 4-dimethyl- 1α, 5α-cyclocholestan-3-one indicates that ring B of the steroid nucleus possesses a boat conformation, and that H-9 partially eclipses the cyclopropyl ring. An anisotropic ring current effect is postulated to account for the chemical shifts of H-9 in these cyclosteroids. The chemistry of these compounds are described. -- Various other attempts at the synthesis of 1a, 5a- cyclosteroids are also described.


identifier: Miller, David O. <https://research.library.mun.ca/view/creator_az/Miller=3ADavid_O=2E=3A=3A.html>   (1989) Synthesis of a novel deazaaminopterin analogue.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis describes the synthesis of a novel deazaaminopterin analogue, which has the glutamate-derived NH group replaced by methylene. This involved the preparation of an aminobenzoyl glutarate by a troublesome decarboxylation of an aroylmalonate, which was studied in some detail. Antibacterial screening revealed activity at 100 μg/mL against Stapliylococcus aureus in the case of the aminopterin analogue, but the aminobenzoylmethylglutarate was inactive against a variety of organisms. -- During synthetic work directed towards the corresponding methotrexate analogue it was found that N-methylation of N-arylbenzenesulfonamides causes enhanced loss of SO₂ in the mass spectrum, as well as interesting shielding effects in the proton and carbon magnetic resonance spectra. This was studied through synthesis and spectroscopic examination of a series of sulfonamides having electron-releasing and/or electron withdrawing substituents.


identifier: Zhou, Yixin <https://research.library.mun.ca/view/creator_az/Zhou=3AYixin=3A=3A.html>   (1995) Raman studies on the aluminate and carbonate anions in aqueous solutions.  Masters thesis, Memorial University of Newfoundland.

abstract: Sodium aluminate solutions and their precipitates have been investigated by Raman spectroscopy. All Raman data are consistent with the existence of Al(OH)₄⁻ and Al₂O(OH)₆ ²⁻ anionic species in sodium aluminate solutions. In supersaturated solutions, both anions are in equilibrium during the induction process. After the induction period, sodium aluminate solutions produce a precipitate which contains neither the Al(OH)₄⁻ anion nor the Al₂O(OH)₆ ²⁻ anion. -- Quantitative Raman studies with 0.23 M NaNO₃ as an internal standard were employed to elucidate the equilibria in sodium aluminate solutions. The best values of the molar scattering constants Ji are equal to 0.25 ± 0.03 for the Al(OH)₄⁻ and 0.57 ± 0.18 for the Al₂O(OH)₆ ²⁻ species relative to the 1.0 M NO₃⁻ ionic mode at 1052 cm⁻¹. With these Ji values the formation quotient Q and equilibrium constant K are estimated. -- In addition, studies of the effects of temperature on the Raman frequencies and halfwiths of CO₃²⁻, Al(OH)₄⁻ and Al(OD)₄ anions in H₂O and D₂O reveal evidence for the presence of strong hydrogen bonds between these anions and water. There is no significant change in the hydrogen band strength at temperatures up to 150°C.


identifier: Shilton, Roy <https://research.library.mun.ca/view/creator_az/Shilton=3ARoy=3A=3A.html>   (1958) The spectra of enones and conjugated dienes.  Masters thesis, Memorial University of Newfoundland.

abstract: The ultra-violet absorption spectra of α,β-unsaturated aldehydes, α,β-unsaturated ketones and conjugated dienes are discussed with special reference to the effect of steric interaction on spectra. Assignments of s-cis or s-trans conformations are made when possible. A modification of the rules for determining wavelength of maximal absorption in conjugated compounds is proposed. Some effects in the spectral curves of conjugated dienes are discussed. Evidence is presented that in these series spectra may be determined by inductive effects.


identifier: Er, Song-Swee <https://research.library.mun.ca/view/creator_az/Er=3ASong-Swee=3A=3A.html>   (1974) The chemical polymerization of pyrryl Mannich base methiodide salt to porphyrins.  Masters thesis, Memorial University of Newfoundland.

abstract: Pyrryl Mannich base methiodides were polymerized in both anhydrous hydroxylic and nonhydroxylic solvents with the hope of clarifying some aspects of the mechanism of porphyrin formation.  Although a mixture of type isomers were obtained, the product composition was found to consist of ~ 95% type (III and IV) and ~ 5% type (I and II) isomers from various solvents.  The results suggested that the isomer composition is not dependent on the presence of “active” hydrogen in the solvent, and polymerization is not due to separation of formaldehyde (or equivalent) from the pyrrole and then a “random” polymerization; formation of type III and IV porphyrins is an inherent property of trimethylaminopyrrole salts and rearrangement in some form is a normal part of polymerization.  On the basis of these results and published data, an intermediate with ring D porphobilinogen unit in the pyrrolenine form at right angles to the macrocycle formed from the other three pyrrole units and methane bridges is suggested and a scheme for the natural type III porphyrin formation is also proposed. -- A new compound diethyl 2,5-dimethyl-3,6-pyrazine-dithiolcarboxylate is reported as a by-product of a pyrryl thiolester synthesis.


identifier: Ho, Chi Keung <https://research.library.mun.ca/view/creator_az/Ho=3AChi_Keung=3A=3A.html>   (1987) The chemistry of the chromotropic acid method for the analysis of formaldehyde.  Masters thesis, Memorial University of Newfoundland.

abstract: Formaldehyde is present in the indoor air of many industrial and non-industrial environments.  The procedure most commonly employed in North America for its analysis is one that uses chromotropic acid and concentrated sulphuric acid.  The nature of the purple chromogen that is produced in the analytical procedure has not been fully understood until now.  Evidence will be presented to support the hypothesis that the chromogen has a mono-cationic dibenzoxanthylium structure and not a para.para-quinoidal one that is commonly cited.


identifier: Xu, Jie <https://research.library.mun.ca/view/creator_az/Xu=3AJie=3A=3A.html>   (1990) The deamination of cytosine: an ab initio SCF mo study.  Masters thesis, Memorial University of Newfoundland.

abstract: In 1974, Lindahl and Nyberg studied the rate of deamination of cytokine residues in single and double stranded DNA. After studying the rate at several temperatures the activation energy for the conversion of cytosine to uracil was estimated to be 121 kJ/mol. -- Possible mechanisms for deamination of cytosine are studied using ab initio SCF molecular orbital calculations. Ab initio calculations with STO-3G, 3-21G and 6-31G* basis sets have been performed to investigate the optimized structures and energies.  -- First the deamination of amidine is studied as a model compound and the calculations are then extended to cytosine. The results for both calculations indicate that the rate-determining step (second step) with OH- has a barrier of 209 kJ/mol and with H₂O has a barrier of 174 kJ/mol. The results show that the reaction is hermodynamically favourable but kinetically not very favourable.


identifier: Wadden, John Terrence <https://research.library.mun.ca/view/creator_az/Wadden=3AJohn_Terrence=3A=3A.html>   (1978) The Kinetics of the ferrous-ferric redox reaction in aqueous perchloric acid.  Masters thesis, Memorial University of Newfoundland.

abstract: The rotating disc electrode (RDE) has been used to investigate the kinetics of the ferrous-ferric redox reaction on platinum, palladium, and gold in aqueous perchloric acid. The electrode shape was optimized, precise speed control was used for the rotating disc and possible noble metal dissolution was minimized during cyclic activation of the test electrode. Each system was studied using counter and reference electrodes constructed from the same metal as the RDE. -- Mass transport effects were eliminated by making a long extrapolation to infinite rotation speed (i₀⁻¹ versus ω⁻¹/²). The data were analyzed in several ways including the slope-intercept method of Jahn and Vielstich and the constant mass transport method of Randles. In this regard, diffusion coefficients of the ferrous and ferric species were determined as well as their temperature dependencies. -- Observed rates were corrected for real surface areas as measured by oxygen desorption of by hydrogen adsorption techniques. Heterogeneous rate constants at 298 K were measured on platinum, gold and palladium and were found to be 5.41 x 10⁻¹³ cm.s⁻¹, 2.11 x 10⁻³ cm.s⁻¹, and 1.77 x 10⁻³ cm.s⁻¹, respectively. A different trend was observed for the pre-exponential factor, A⁺, decreasing from gold to platinum to palladium. Experimental activation enthalpies for all three metals were essentially constant within experimental error having a median value of 39 ± 3.5 kJ.mol⁻¹. An attempt was made to correlate kinetic parameters with the thermionic work function of each metal. The possible effect upon the kinetics of chloride impurity, arising from reduction of the perchlorate ion was also considered. Utilizing radiochemical chloride adsorption data, the rate constants of the reaction on a chloride-free and fully covered platinum electrode were estimated to be 2.62 x 10⁻⁵ and 6.76 x 10⁻³ cm.s⁻¹ respectively.


identifier: Paulse, Chris D. <https://research.library.mun.ca/view/creator_az/Paulse=3AChris_D=2E=3A=3A.html>   (1990) The microwave spectra of two halogenated pyrimidines.  Masters thesis, Memorial University of Newfoundland.

abstract: The microwave spectra of seven isotopomers of 2-chloropyrimidine have been measured in the 33-80 GHz frequency range. These data have been analysed to yield, in the first instance, values of rotational constants, quartic centrifugal distortion constants and chlorine nuclear quadrupole coupling constants. The isotopic rotational constants confirm that the molecule is planar and has C₂ν symmetry and have allowed the determination of partial substitution and ground state effective molecular geometries. For the normal isotopic species the pure rotational spectra of the molecule in five excited vibrational states have been observed and assignments made to vibrational quantum numbers on the bases of the observed inertial defects. A careful analysis of the nitrogen nuclear quadrupole hyperfine structure for the molecule 2-fluoropyrimidine is also presented. The experimental values of chlorine and nitrogen nuclear quadrupole coupling constants determined here are compared with the results of ab initio SCF calculations of the electric field gradients at the chlorine and nitrogen nuclei using a series of contracted Gaussian basis sets.


identifier: Hancock, Gary Robert <https://research.library.mun.ca/view/creator_az/Hancock=3AGary_Robert=3A=3A.html>   (1984) Photo-assisted electrolysis of water using p-type III-V semiconductors.  Masters thesis, Memorial University of Newfoundland.

abstract: The recent interest in photoelectrochemical methods of solar energy conversion has led to the investigation of many semiconductors for their suitability as electrodes for the process. Attempts have also been made to improve the photoelectrochemical performance of many of these semiconductor electrodes by various surface treatments. -- In the first part of this work, the current density-potential characteristics for the photo-assisted electrolysis of water were compared for p-GaP, P-GaAs and p-InP photocathodes, unplated and with thin electrodeposits (2-200-monolayers) of platinum or palladium. The photocathodes were used in a cell with a platinum anode and 0.5 M H₂SO₄ as electrolyte. For all three semiconductors the noble metal platings resulted in favourable positive potential shifts of the cathodic current-potential curves. Positive energy conversion efficiencies were realized (maximum value of 0.03% in 200 mW.cm⁻² simulated sunlight) for GaP only. It is suggested that the noble metal atoms plated on the surface improve performance by catalytic acceleration of the hydrogen evolution reactions (h.e.r.). -- In the second part of this work photoelectrochemical kinetic parameters were determined for the h.e.r. on the same three semiconductors in 0.5 M H₂SO₄. Room temperature measurements showed the results to conform reasonably well to equations derived by W.L. Ahlgren, based largely on theory developed by J.F. Dewald and H. Gerischer, and modified here for the particular situation of interest. The method involved recording current-potential characteristics at several light intensities and extracting data from them to construct a so-called Ahlgren plot to yield the exchange current density. A jacketed cell was employed later to enable exchange current densities at several temperatures to be determined and used to construct Arrhenius plots. The average values of the exchange current densities (in μA.cm⁻² at 298 K) were 5 x 10⁻², 3 x 10⁻² and 2 x 10⁻⁴ for GaP, GaAs and InP, respectively. The weighted mean activation enthalpies, in kJ.mol⁻¹, were 16.0 for GaP, 25.7 for GaAs, and 61.6 for InP. These results suggest that for the h.e.r. on the bare (unplated) electrodes, GaP is a more suitable electrode than GaAs, and both are much better than InP. -- The agreement with theory and problems of achieving reproducibility are discussed. The significance of the exchange current densities and activation enthalpies determined by this method is explained and a comparison of the exchange current densities with those for the h.e.r. on some metals is presented. Some recent promising work by other researchers is documented and suggestions for future experiments made.


identifier: Tan, Beck Yu Yap <https://research.library.mun.ca/view/creator_az/Tan=3ABeck_Yu_Yap=3A=3A.html>   (1975) A study of sulfur and selenium containing ligands.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: The substituted (arylthio)-, (arylseleno)- and (arylsulfoxy)- acetic acids, RC₆H₄YCH₂CO₂H (Y = S, Se, So; -R = H o, m, p-CH ₃) are studied as ligands towards Pt(II), Pd(II) and Cu(II) ions. The thoi and seleno ligands RC₆H₄XCH₂CO₂H (X = S, Se) form bis-complexes, ML₂, with Pt(II) and Pd(II) whereas the sulfoxy ligands (Y = SO) form only complexed ions (MLX₂)⁻ with Pt(II) and Pd(II) (where X = Cl, Br). -- The bis-complexes of platinum(II) and palladium(II) are coordinated via the thio or seleno group and the carboxylate group of the ligands. The assignment of trans structure is based on the non-coincidence of the υM-O and υM-S bands in the infrared and Raman spectra and also from steric consideration. In these bis-complexes, chelate formation causes magnetic inequivalence of the methylene protons in the ¹H n.m.r. spectra. In addition the presence of chiral centers at sulfur or selenium atoms results in the observations of two sets of methyl and methylene absorptions which coalesce at high temperature. This phenomenon of the ¹H n.m.r. spectra indicates the co-existence of the diastereoisomers (meso and dl). -- (Arylsulfoxy) acetic acid is a potential ambident ligand. In the sulfoxy complexed ions (MLX₂)⁻ the sulfoxy group utilizes the sulfur atom in bonding. The effects of chelatiori and strong electron withdrawing ability of the sulfoxy group render the methylene protons acidic. -- For the bis-complexes of copper(II), CuL₂, (Y = S, Se; R = m or p=CH₃), whether the S or Se atoms participate in the chelate formation is still not clear.


identifier: Wang, Youliang <https://research.library.mun.ca/view/creator_az/Wang=3AYouliang=3A=3A.html>   (1995) A study of ab initio generalized valence bond theory: methodology, programming and applications.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: Please see thesis for abstract.


identifier: Kean, Christopher L. <https://research.library.mun.ca/view/creator_az/Kean=3AChristopher_L=2E=3A=3A.html>   (2001) Dithiolene based conjugated metallopolymers.  Masters thesis, Memorial University of Newfoundland.

abstract: Incorporation of metals into conjugated organic polymers is a relatively novel concept, and offers promise for the development of advanced electronic, catalytic and sensing materials. Dithiolene complexes are attractive building blocks for such systems since they exhibit superconductivity and have been shown to display interesting non-linear optical properties. Also, their aromaticity provides for facile n-doping. -- This project entails the synthesis of several monomeric nickel dithiolene complexes having peripheral thiophene moieties. These thiophene units permit electropolymerization of these complexes to yield metallopolymers which have 100% coordination of a metal center. Redox properties of both complexes and polymeric films were characterized by cyclic voltammetry. Also described is the further characterization of poly(bis[1,2-di(2-thienyl)-1,2-ethenedithiolene]-nickel) by electronic absorption, spectroelectrochemistry and conductivity measurements. The later were accomplished by impedance spectroscopy and interdigitated microsensor electrodes. The conductivity of poly(bis[1,2-di(2-thienyl)-1,2-ethenedithiolene]nickel) was determined to be 10-6 S cm-1 and 10-4 S cm-1 at +0.2 V and +1.0 V respectively. It is anticipated that further optimization of film growth procedures will lead to an increase in these conductivities.


identifier: Tang, Shu <https://research.library.mun.ca/view/creator_az/Tang=3AShu=3A=3A.html>   (1999) Characterization of thiophene-based conducting polymers by pyrolysis-gas chromatography-mass spectrometry.  Masters thesis, Memorial University of Newfoundland.

abstract: Conducting polymers have attracted great attention since their discovery at the end of the 70's due to their high conductivity, versatility and structural flexibility. Various methods have been developed for their structural characterization but few are useful for microstructure elucidation. This study demonstrates the ability of Pyroiysis-Gas Chromatography-Mass Spectrometry to examine both the thermal degradation behavior and microstructure of thiophene-based conducting polymers. -- Unsubstituted polythiophenes, i.e., polythiophene, poly(2,2'-bithiophene),  and poly(2,2':5',2"-terthiophene) were prepared by galvanostatical electropolymerization. β-substituted polythiophenes, i.e. poly (3-alkylthiophene)s (alkyl = methyl, hexyl, octyl), poly(3-methoxythiophene) and poly(3,4-ethylenedioxy-thiophene), were synthesized either electrochemicaliy or chemically. Optimum pyrolysis temperatures for high yields of structurally-important fragments were established by investigating pyrolysis temperatures from 300 to 1400°C. Comparison of polythiophenes shows that the yield of H₂S decreases, while the yield of thiophene oligomer fragments increases, as the chain length of the precursor oligomer increases. These results reflect decreasing the conjugation length from polythiophene to poiyterthiophene. The predominant polymeric  linkage in unsubstituted polythiophenes is α-α' along with non-negligible amounts of α-β' linkage. Evidence of partial overoxidation of polythiophene during electropolymerization was also obtained from the pyrograms. Structural analysis of oligomer fragments obtained from pyrolysis of poly(3-alkylthiophene)s gave useful stereoregularity information (i.e., head / tail configurations). Furthermore, based on the pyrolysis products, possible degradation pathways of poly(3-alkylthiophene)s were established.


identifier: Ren, Xiaoming <https://research.library.mun.ca/view/creator_az/Ren=3AXiaoming=3A=3A.html>   (1993) Charge transport in polypyrrole-based conducting polymers.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract: Impedance spectroscopy has been used to study polypyrrole/perchlorate (PPY/CIO₄), PPY/poly(styrene sulphonate) (PPY/PSS), poly-(3-methyl-pyrrole-4-carboxylic acid) (poly-MPCA), poly-[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium] (poly-MPMP), bilayers of PPY/CIO₄ and PPY/PSS, and polypyrrole formed in mixed perchlorate and poly(styrene sulphonate) (PPY/CIO₄ +PSS) polymer films coated Pt electrodes in electrolyte solutions. All impedance  responses can be modelled with a porous electrode theory to extract reliable electronic and ionic conductivities, which agree with the results of other independent measurements. -- The impedances of PPY/CIO₄ and PPY/PSS reveal dominant anion  and cation transport, respectively, in these polymers. A strong interaction between the anions and the positive charges on the oxidized polypyrrole chains hinders anion movement in PPY/CIO₄. Absence of such an interaction for the  mobile cations in PPY/PSS gives this polymer a ca. 20 times higher ionic conductivity than PPY/CIO₄. -- Deviation from the ideal model impedance response occurs for poly-MPCA because of its non-uniform structure. Mixed ion conduction can cause another type of deviation as shown by the impedance of PPY/CIO₄ +PSS polymers and the simulated data. High frequency data for reduced films of PPY/PSS and poly-MPCA form a semicircle in the complex impedance plane. This semicircle is attributed to electron transfer at the Pt/polymer interface for PPY/PSS but ion transfer at the polymer/solution interface for poly-MPCA. -- The impedances of the PPY/CIO₄ and PPY/PSS bilayer films show that the location of the initial reaction induced by a potential perturbation for a highly conducting PPY film coated electrode is at the polymer/solution interface. The impedances of poly-MPMP and PPY/PSS show that the location of the initial reaction depends on the relative magnitudes of the film's electronic and ionic conductivities, as theoretically predicted. -- Ionic conductivity measurements were used to probe polymer structure. Films of PPY/CIO₄, PPY/PSS and poly-MPCA all have a two phase structure, a polymer phase and a pore solution phase. Ionic conduction in  the polymer phase occurs mainly through the movement of mobile counterions via an ion-exchanging process, while in the pore solution phase migration of both electrolyte cations and anions contributes to conduction.


identifier: Chai, Wenmao <https://research.library.mun.ca/view/creator_az/Chai=3AWenmao=3A=3A.html>   (1994) A parallel algorithm of constructing a Voronoi diagram on hypercube connected computer networks.  Masters thesis, Memorial University of Newfoundland.

abstract: Computational geometry is a branch of computer science concerned with the design and analysis of algorithms to solve geometric problems. The Voronoi diagram of a set S of n points (called sites) is a well known structure in computational geometry. In the Voronoi diagram, each point is surrounded by a convex polygon enclosing that territory which is closer to the surrounded point than to any other point in the set. Voronoi diagrams are useful in solving geometric problems such as proximity problems and the Euclidean minimum spanning tree problem. Voronoi diagrams also have applications in diverse areas like biology, visual  perception, physics, and archeology. -- There exist many methods to construct Voronoi diagrams on a single computer. Two of them are proposed by Shamos and Brown. In 1975, Shamos applied two-dimensional Voronoi diagrams to obtain elegant solutions in computational geometry, such as finding the nearest neighbor and construction of minimum spanning trees. Shamos described an O(n log n) time sequential algorithm to construct the planar Voronoi diagram for a set of planar points. The strategy he used in the serial algorithm is divide-and-conquer. In 1979, Brown demonstrated  an interesting linkage between the Voronoi diagram and the convex hull. He presented an O(n log n) algorithm for constructing the Voronoi diagram, by transforming the problem of constructing a planar Voronoi diagram for an n-points set to the construction of a convex hull of n points in 3-dimensional space via a geometric transformation known as inversion. -- Due to the nature of some applications in which geometric problems arise, fast and even real-time algorithms are often required. Here, as in many other areas,  parallelism seems to hold the greatest promise for major reduction in computation time. The idea is to use several processors which cooperate to solve a given problem simultaneously in a fraction of the time taken by a single processor. Therefore, it is not surprising that the interest  in parallel algorithms for geometric problems has grown in recent years. -- Based on Shamos's and Brown's methods, several parallel algorithms to construct Voronoi diagrams have been presented. Some of them are implemented on parallel random access machines. Some of them are run on processor networks such as mesh, cube-connected cycles, stars and pancakes. We will discuss them in the literature review. With the development of communication technique and concurrent programming, computer networks have become popular. The most popular processor interconnection topology  today is undoubtedly the hypercube. Hypercubes have several advantages. First, the number of nodes in a hypercube grows exponentially with the number of connections per node, so that a small increase in the hardware at each node allows a large increase in the size of the computer. Second, the number of alternative paths between nodes increases with the  size of the hypercube, which helps relieve congestion. Third, efficient algorithms are known for routing messages between processors in a hypercube. Finally, and today most importantly, a large corpus of software and programming techniques exists for hypercube. -- The hypercube is one of the most versatile and efficient networks yet discovered for  parallel computation. In this thesis, a single instruction multiple data stream hypercube connected computer network is  chosen as our parallel computation model. In a hypercube connected computer network, local computations as well as message exchanges are taken into consideration when analyzing the time taken by the processor networks to solve a problem. Based on Nassimi and Sahni's paper fundamental operations on hypercube connect computer networks are descriptively discussed. The corresponding programs are also  given. Based on Brown's approach, a parallel algorithm to construct Voronoi diagrams are developed. Our algorithm runs  in O(log³n) time on an O(n)-processor hypercube connected computer network. Our algorithm has several advantages. First, our algorithm is based on Brown's method which transforms the problem of construction of a planar a Voronoi  diagram for an n-point set to construction of a convex hull of n points in three dimensional space. Compared with the parallel algorithms which are based on the divide-and-conquer approach used by Shamos, our algorithm can be used to solve two computational geometry problems: constructing 2—dimensional Voronoi diagrams and 3—dimensional convex hulls. Second, comparing with Chow's methods which runs on a  O(n) processors CCC (Cube-Connected Cycles) model has O(log⁴n) time complexity, our algorithm has better time complexity. Third, comparing with Chang-Sung Jeong's algorithm which runs in O(√n) on an √n x √n mesh, our parallel computation model is more general because most other popular networks can be easily mapped onto a hypercube.


identifier: Brake, Robert Blaine Boyd <https://research.library.mun.ca/view/creator_az/Brake=3ARobert_Blaine_Boyd=3A=3A.html>   (1985) Implementation of data abstractions via an event based program transformation technique.  Masters thesis, Memorial University of Newfoundland.

abstract: Conventional data abstraction techniques enhance several aspects of a software system, its development, maintainability, reusability and comprehensibility.  However, using conventional techniques one must manually implement a data abstraction and it's operators, which may result in an inefficient implementation. -- This paper introduces a program transformation technique which mechanically implements a fixed data abstraction with a limited set of efficient implementations. -- Within the limited scope, the event based technique has all the advantages of the conventional methods, as well as, automatic and efficient implementation by using an inline coding technique which is based on the properties (attributes) of the data representation being used to implement the data abstraction.


identifier: Lu, Xi <https://research.library.mun.ca/view/creator_az/Lu=3AXi=3A=3A.html>   (1995) A graphical user interface for CAD programs.  Masters thesis, Memorial University of Newfoundland.

abstract: The aim of this project is to outline the design and implementation of graphical user interfaces for engineering and scientific computer-aided design tools.  Graphical interfaces are quite important for sophisticated software tools because they simplify the use of the tools and reduce the learning phase.  A properly designed user interface "guides" a user through the interactions with design tools, clearly indicating the design decisions and supplying all relevant information which is helpful in making these decisions. -- A package for graphical presentation and manipulation of numerical results is designed and implemented for existing computer aided design programs SPICE-PAC and FIT.  The implementation is based on the Athena widget set under the X Window system. -- The methodology developed during this project is applicable to many other tools, reducing their development time and simplifying the use of developed programs.


identifier: Chen, Zhenjie <https://research.library.mun.ca/view/creator_az/Chen=3AZhenjie=3A=3A.html>   (1995) Dependence analysis and evaluation of inherent parallelism of programs.  Masters thesis, Memorial University of Newfoundland.

abstract: Dependencies are relations between statements of a program. They indicate the constraints imposed on the order of statement execution, and are often used for the evaluation, optimization, vectorization and parallelization of programs. By means of dependence analysis, much work has been done to exploit the parallelism in the loops in which there are no dependencies that cross from one iteration of the loop to another. Only recently an approach was proposed for exploiting the parallelism available in loops with cross-iteration dependencies. -- The aim of this project is to evaluate inherent parallelism of sequential programs by means of dependence analysis. The thesis first introduces the definitions, concepts and basic dependency analysis algorithms, and presents a uniform representation of dependencies called a dependence graph. Then, using the dependence graph, a general approach is presented which can be used to analyze the parallelism between loops as well as between loops and other parts of a program. This approach was implemented as a program called DSA (Dependence and Speedup Analyzer), used to perform the dependence analysis and to evaluate the inherent parallelism of Fortran programs. Finally, the implementation of DSA is briefly described and its use is illustrated by a series of examples.


identifier: Shi, Zhimin <https://research.library.mun.ca/view/creator_az/Shi=3AZhimin=3A=3A.html>   (1994) Exploring linear speedup in parallel ATPG through special topology.  Masters thesis, Memorial University of Newfoundland.

abstract: In digital system design, test pattern generation requires a  considerable amount of computing time. Using a level-sensitive scan design, test pattern generation can be confined to the combinational circuits. It has been shown that the problem of test pattern generation for combinational circuits is NP-complete. Although many excellent algorithms have been developed to generate test patterns, they still do not keep pace with VLSI technology. Research is ongoing in the development of parallel processing techniques for test pattern generation, but there has been little research into what kind of topology has the greatest potential to speed up test pattern generation. -- In this work, simulation software was developed for measurement of the speedup, and three topologies are proposed to explore the parallelism for automatic test pattern generation. These topologies are: modified complete binary tree (MCBTA), autonomous modified complete binary tree (AMCBTA), and square array structure (SQARRAY). The empirical results for these topologies show that a special topology has the potential capability to speed up test pattern generation and super-linear speedup can often result  if an autonomous structure is adopted.


identifier: Craig, Donald C. <https://research.library.mun.ca/view/creator_az/Craig=3ADonald_C=2E=3A=3A.html>   (1996) Extensible hierarchical object-oriented logic simulation with an adaptable graphical user interface.  Masters thesis, Memorial University of Newfoundland.

abstract: Simulators provide an economical means of understanding and evaluating the performance of both abstract and real world systems. In addition to being efficient and easy to use, modern day simulators must be able to cope with the demands of increasing complexity within systems. Simulators must also be easily extensible so that the behaviour and performance of a wide variety of systems may be studied. -- This report will outline the design and implementation of a utility which integrates an interactive, graphical design tool with a discrete event simulation engine that employs the object-oriented paradigm as a means of combating complexity. Central to the simulation technique is the concept of local time, in which each entity being simulated maintains its own notion of time throughout the simulation. This concept promotes component encapsulation and self-containment thereby facilitating the implementation of distributed event-driven simulators. Although the simulation  domain described in this report will consist primarily of digital logic circuits, the simulation techniques should also be amenable to the simulation of any discrete event system. -- The graphical user interface front-end to the simulator engine is designed to be easy to use, hence making  the underlying simulator engine accessible to a wide audience. The implementation of the interface is loosely integrated with the simulator engine, thereby providing a high degree flexibility between the interface and the simulator itself. The interface and the simulator can each operate as distinct, self-contained applications. As a result, the simulator engine could be configured to employ a  different graphical interface and the graphical interface can be adapted for a variety of existing text-based simulator engines.


identifier: Luo, Xiao <https://research.library.mun.ca/view/creator_az/Luo=3AXiao=3A=3A.html>   (1989) A VLSI design for an efficient multiprocessor cache memory.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis proposes a cache memory, used for a 32-bit processor system, which consists of four components: the Directory, Line Replacement Unit (LRU), Cache Memory, and Control Unit. An 8-way set-associative mapping method is employed in the directory. The Line Replacement Unit is based on the least recently used line replacement algorithm.  The cache memory unit has a capacity of 8k bytes, 32 bytes in each line, and it is directly accessible to 1, 2, 3, or 4  bytes (one word) once by the associated processor. This cache memory is designed for a multiple processor system as well as in single processor system; a write-through algorithm and an updating algorithm are combined together to  keep the information in main memory consistent with that of the cache and to make the multicaches coherent. The hit ratios are predicted to be over 95 percent. A two-phase clock of 40ns is employed to pipeline this cache, and it can  turn out a result in 20ns during read operations without line misses. This cache is implemented into a single chip, and is designed so that it is possible to build cache systems of various sizes using these chips, without decreasing the system speed. This cache memory has been laid  out as a single integrated circuit using 3 Micron NTCMOS technology, and its electrical and logical behavior has been  simulated.


identifier: Venguswamy, Kumar <https://research.library.mun.ca/view/creator_az/Venguswamy=3AKumar=3A=3A.html>   (1990) An analysis of the single row transformation (SRT) approach to VLSI channel routing.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis addresses the problem of detailed routing of Very Large Scale Integrated (VLSI) circuits using channel routing. Recently, a novel approach to detailed VLSI routing  has been proposed by Wong and Kwok [Wong88]. This method, called the Single Row Transformation (SRT) approach, requires three steps, namely, Forward Transformation (FT), Single Row Routing (SRR) and finally Backward Transformation  (BT). When this apparently simple approach was looked at more closely, it was realised that this approach has many hidden problems, the most important being those posed by the  crossovers in the SRR layout while carrying out the BT step.  Thus, although SRT based routing appeared to be a potential approach, further research was required. The goal of this thesis is to make a study and analysis of the SRT approach as it applies to channel routing, and to use the results of the analysis to design a channel router. -- Although different FT-BT pairs are possible, only straightforward pairs are practical, and even for simple FT-BT pairs the problems posed by crossovers in the SRR solution necessitate  a minimum crossover routing, calling for the design of new algorithms, because most of the existing SRR algorithms have  been designed with the goal of track optimisation, not crossover minimisation. To facilitate the design of these algorithms, a taxonomy of SRR problems is useful. A proposed  taxonomy classifies SRR problems into bipartite and non-bipartite problems, and further into permutation and mixed SRR problems. Based on this taxonomy, various algorithms for  the different classes of SRR problems have been developed. Since some crossovers may he inevitable, effective crossover  handling techniques are necessary. To this end different crossover handling techniques are discussed and a generalised crossover handling technique is proposed. The application of the analysis to the software design of a channel router and implementation of this software is also addressed.


identifier: Chen, Hao <https://research.library.mun.ca/view/creator_az/Chen=3AHao=3A=3A.html>   (1994) An efficient mutual exclusion method in distributed systems.  Masters thesis, Memorial University of Newfoundland.

abstract: Many operations in a distributed system require mutual exclusion to guarantee correctness.  Quorum methods have been widely proposed for implementing mutual exclusion.  Majority quorum consensus is the best known quorum method.  It has the merit of simplicity, but may incur high message overhead.  Tree algorithm is an efficient structured quorum method to the mutual exclusion problems.  The quorums generated by a tree algorithm are smaller on the average than those by a majority quorum consensus.  However, the tree algorithm enforces a highly biased treatment to the nodes at different levels.  This affects its performance in a distributed system where the nodes have similar characteristics.  We propose a new structured quorum method called triangular net quorum algorithm, which treats the nodes more evenly than the tree algorithm while preserving a satisfactory availability, as well as lowering average quorum size.  We believe that this method is desirable for implementing mutual exclusion in a truly distributed system.


identifier: Wee, Dennis Ju-Xieng <https://research.library.mun.ca/view/creator_az/Wee=3ADennis_Ju-Xieng=3A=3A.html>   (1993) Formal software development using Z and the refinement calculus.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis is a study of a formal software development process that uses a formal specification language called Z [42] and the formal development method called the refinement  calculus [31]. The software development process is divided into five stages: formal specification in Z, data refinement, translation into the refinement calculus, operation refinement, and translation into the target programming language [25]. In this thesis, many of the important results for understanding and using this process are collected together and numerous examples are given to illustrate their use. Through a case study of the Paragraph Problem [5, 31], we show how formality may be appropriately employed to manage the algorithmic complexity in a development, and indicate directions on how predefined programming language and library routines may be introduced into a formal development. The thesis concludes with some suggestions for further research.


identifier: Szeto, Anthony Wing Kay <https://research.library.mun.ca/view/creator_az/Szeto=3AAnthony_Wing_Kay=3A=3A.html>   (1991) Hierarchical neural network system for improving edge detection.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis presents a hierarchical neural network system for improving the edge measurements obtained by an edge operator.  The neural network system is designed to adjust the edge measurements based on the information provided by neighbouring edges.  The adopted strategy is to analyze the local edge patterns to determine and reinforce edge structures while suppressing unwanted noise and false edges.  The hierarchical neural network system is made up of four levels of subnets.  The subnet in the first level consists of high-order neural nets to determine the potential adjustment on the element of interest by detecting edge contours according to the selected processes in the neural nets and the input local edge pattern.  The second level consists of a cooperative-competitive neural net model to determine the orientation of the strongest edge contour in the local edge pattern.  The subnet in the third level consists of two types of neural net models.  A high-order neural net ascertains the conditions for adjusting the gradient magnitude and determines the amount of adjustment to the gradient magnitude.  A semilinear feedforward net is used to compute the new adjusted gradient magnitude and determines if the element of interest is to be an edge element or a non-edge element.  The subnet in level four is a semilinear feedforward net which is used to determine the new orientation for the element of interest.  A fast learning algorithm is developed to derive suitable weights for the neural nets to perform efficiently and correctly.  Using the hierarchical neural network system for each element in the image, highly parallel processing can be achieved.  An iterative approach incorporated into the neural network system has also enabled the application of global analysis in the process of adjusting the edge measurements.  As a result, the final edge measurements are more accurate.


identifier: Ren, Ying <https://research.library.mun.ca/view/creator_az/Ren=3AYing=3A=3A.html>   (1991) Hierarchichal attributed graph representation and recognition of handwritten Chinese characters.  Masters thesis, Memorial University of Newfoundland.

abstract: This thesis presents a system which is capable of recognizing handwritten Chinese characters.  The hierarchical attributed graph representation (HAGR), a two-level graph, is introduced to describe the structural and statistical information of handwritten Chinese characters.  The first level describes radicals and relations between radicals within a character, the second level describes strokes and relations between strokes in a radical.  With HAGR, the recognition process becomes a simple task of graph matching.  A cost function mapping a candidate to a model graph is introduced.  This approach can tolerate the variations of HAGR which reflect the instablities and variabilities of handwritten Chinese characters resulting from different writing styles.  Several rules have been used to re-arrange the order of the vertices of the graphs in order to avoid the combinatorial explosion inherent in graph matching.  Based on HAGR, the model database is organized as a heterogeneous multi-way tree structure.  For an input character, the search process can be divided into a number of simple and local decisions at different levels of the tree to find a corresponding model character in the database.  The matching process is very efficient and accurate, and as well the system can acquire representations of characters by a learning process.  Several HAGRs of samples of a character can be synthesized into a single HAGR of the character which can then be included in the model database.  In addition, the learning process can update the models of characters with the HAGRs of their samples.  The system is implemented in C on a MIPS/M-120 running RISC/OS (Version-3.1).


identifier: Muthu, Muthuraman <https://research.library.mun.ca/view/creator_az/Muthu=3AMuthuraman=3A=3A.html>   (1997) High-level specification of graphical user interfaces.  Masters thesis, Memorial University of Newfoundland.

abstract: Recent studies have shown that users of GUIs make fewer mistakes, feel less frustrated, suffer less fatigue and are more able to learn for themselves about the operation of new packages than users of non-graphical or character-based user interfaces.  On the other hand, other surveys on user interface programming show that developing a GUI is a very complex task, that in today's applications a considerable amount of resources (time and effort) are devoted to the user interface portion both in the development phase and in the maintenance phase. -- This report discusses currently available toolkits and specification methods that facilitate the development of a GUI in an efficient way and compares their merits and demerits.  A new solution is then proposed by developing a high-level specification language for interfaces.  The proposed approach is implemented using Java/JavaCompilerCompiler (JavaCC).  A simple application is also presented. -- Key Words: Graphical User Interfaces; Toolkits; Interface Specification Languages; User Interface Design.