Thesis (Ph. D.)--Columbia University, 1917. / Vita.

Thesis (M.S.)--University of Wisconsin--Madison, 1949. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 12-13).

Thesis (Ph.D.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 29, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Bioresource and Food Engineering, Department of Agricultural, Food and Nutritional Science, University of Alberta. Includes bibliographical references.

Thesis (Ph.D.)(Biotechnology)--University of Pretoria, 2004. / Title from opening screen (viewed March 27, 2006). Includes summary. Includes bibliographical references.

Thesis (MScAgric)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Essential oils are derived from volatile natural oils in plants and have been used by mankind for millennia. Citrus essential oils are widely used in various applications and lemon [Citrus limon (L.) Burm. f.] rind oil is the most important citrus oil in commerce. Rind oil glands are located in the exocarp, or flavedo, of the fruit and are formed schizogenously. The purpose of this study was to quantify the factors affecting rind oil content of lemons. The factors studied were light exposure and canopy position, growing region in South Africa, genotype, i.e. scion and rootstock, as well as the relationship between seedless clones of cultivars and the cultivars from which the seedless clones were derived, and various plant growth regulators were screened to determine whether they influenced rind oil content. Following the sampling of fruit from different positions in the tree's canopy, light exposure was found to affect rind oil content of 'Eureka' lemon fruit. Fruit borne on the outside of trees, higher in the tree, north-facing or not within the hedgerow had the highest rind oil content. Photosynthetically active radiation data supports the hypothesis that rind oil content is correlated with light exposure. To optimise rind oil content of lemons, trees should not be too dense or too high as to overshadow the lower parts of adjacent trees. South Africa has a diverse climate, and rind oil content from fruit produced in different growing regions was compared. 'Eureka' lemon fruit from Upington had the highest rind oil content in all seasons sampled. Fruit from Malelane and Marble Hall ranked second to Upington and rind oil content for fruit from Karino was intermediate. Rind oil content for fruit from Vaalharts was the lowest at each sampling time. When rind oil content was regressed against cumulative heat units there was a positive linear relationship in 2003, but in 2004 the relationship was weak. However, III general, rind oil content increased with increasing heat unit accumulation. A large variation exists among citrus cultivars and rootstocks and their effect on fruit growth and quality. 'Lirnoneira 8A', followed by 'Cicily', 'Lisbon' and 'Genoa' had the highest rind oil content. 'Villafranca', 'Messina' and 'Yen Ben Lisbon' had the lowest rind oil content. Rind oil content from 'Eureka' lemon fruit was disappointingly low. Seedless cultivars, 'Eureka SL' and 'Lisbon SL', had ~18.0% higher rind oil content than the seeded cultivars from which they were derived. With regards to rootstock, fruit from lemon trees budded on non-invigorating rootstocks, e.g. X639 [e. reshni Hort. ex Tan. x P. trifoliata (L.) Raf.], had the highest rind oil content, whereas rind oil content was low on invigorating rootstocks such as rough lemon (e. jambhiri Lush.). Synthetic gibberellins, cytokinins, ethylene and auxins were applied on lemon trees at different times and concentrations to screen their ability to enhance rind oil content. Of all the gibberellins and cytokinins applied, Promalin®, a combination of gibberellic acid 4/7 and benzyl adenine-phosphate, a cytokinin, had a small, but nonsignificant effect on rind oil content. Ethephon, which induces ethylene synthesis, affected rind oil content in 2004, when applied 8 weeks before harvest. However, ethephon and aminoethoxyvinylglycine (AVG, an ethylene biosynthesis inhibitor) had an inconsistent effect on lemon rind oil content. Auxins did not affect rind oil content. Further experiments should be conducted, especially on the timing and concentration of applied gibberellins, e.g. Promalin®, and ethephon. / AFRIKAANSE OPSOMMING: Essensiële olies is vlugtige, natuurlike plantolies wat al vir eeue deur die mens gebruik word. Sitrus essensiële olies het verskeie toepassings en van hierdie sitrus olies is dié verkry uit suurlemoenskil [Citrus limon (L.) Burm. f.] die belangrikste. Skiloliekliere is in die eksokarp, of flavedo, van die vrug geleë en vorm skisogenies. Die doelwit van hierdie navorsing was om faktore wat die olie-inhoud van suurlemoenskil affekteer te kwantifiseer. Faktore wat bestudeer is sluit ligblootstelling en posisie in die boom, produksiearea in Suid-Afrika, en genotipe (bo- en onderstam) in. Ook is saadlose klone vergelyk met die kultivars waaruit dit ontwikkel is. Verskeie plantgroeireguleerders se effek op skilolie-inhoud is ook geëvalueer. Ligblootstelling het skilolie-inhoud van 'Eureka' suurlemoene affekteer toe monsters van verskillende posisies in die boomtop vergelyk is. Vrugte aan die noorde- en buitekant, of hoër in die boom het die hoogste skilolie-inhoud gehad. Vrugte binne die plantry het minder skilolie bevat. Fotosinteties-aktiewe ligvlakmetings ondersteun die hipotese dat skilolieinhoud korreleer met ligblootstelling. Vir opitmale skilolie-inhoud in suurlemoene is dit dus belangrik dat bome nie te dig of te hoog moet wees nie, sodat dit nie die onderste dele van aangrensende bome oorskadu nie. Sitrus word in diverse klimaatstreke in Suid-Afrika verbou. Gevolglik is die skilolie-inhoud van vrugte uit verskillende produksieareas vergelyk. 'Eureka' suurlemoenvrugte uit Upington het met elke monsterneming die hoogste skilolie-inhoud gehad, gevolg deur vrugte uit Malelane en Marble Hall. Skilolie-inhoud van vrugte uit Karino was gemiddeld, terwyl vrugte van Vaalhaarts met elke monsterneming die laagste skilolie-inhoud gehad het. Regressie van skilolie-inhoud op kumulatiewe hitte-eenhede het 'n positiewe lineêre verwantskap in 2003 getoon. Hoewel die verwantskap swakker was in 2004, neem skilolieinhoud oor die algemeen toe met toenemende akkumulasie van hitte-eenhede. Sitruskultivars en -onderstamme varieer aansienlik in groeikrag en vrugkwaliteit. 'Lirnoneira 8A', gevolg deur 'Cicily', 'Lisbon' en 'Genoa' het die hoogste skilolie-inhoud gehad, terwyl 'Villafranca', 'Messina' en 'Yen Ben Lisbon' die laagste skilolie-inhoud gehad het. Die skilolie-inhoud van 'Eureka' suurlemoene was teleurstellend laag. Die skilolie-inhoud van die saadlose kultivars, 'Eureka SL' en 'Lisbon SL', was -18% hoër as die skilolie-inhoud van die kultivars waaruit dit ontwikkel is. Vrugte van bome wat op minder groeikragtige onderstamme geënt is, bv. X639 [C reshni Hort. ex Tan. x P. trifoliata (L.) Raf.], het 'n hoë skilolie-inhoud gehad, terwyl vrugte van bome op groeikragtige onderstamme, bv. growweskilsuurlemoen (C jambhiri Lush.), minder skilolie bevat het. Sintetiese gibberelliene, sitokiniene, etileen en ouksiene is op verskillende tye en teen verskillende dosisse op suurlemoenbome toegedien om die effek daarvan op skilolie-inhoud te bepaal. Promalin® (G~+7 en bensieladenienfosfaat) het 'n klein effek op skilolie-inhoud gehad, maar die effek was nie statisties beduidend nie. Ethephon, wat etileensintese induseer, het skilolie-inhoud in 2004 geaffekteer toe dit 8 weke voor oes toegedien is. Ethephon en aminoetoksievinielglisien (AVG, 'n etileenbiosintese inhibeerder) het egter nie 'n konstante effek op suurlemoen skilolie-inhoud gehad nie. Ouksiene het nie skilolie-inhoud geaffekteer me. Verdere eksperimente is veral nodig op die toedieningstyd en konsentrasie van toegediende gibberelliene, bv. Promalin®, en ethephon.

Blends of lubricant base stocks are commonly employed to produce lubricants with optimised performance. However, the influence of blending on lubricant behaviour within high pressure, mechanical contacts, particularly the film forming capacity and friction, have largely gone unstudied. This thesis examines both of these aspects for a range of base fluids and their blends. Film thickness generation and fluid friction are reviewed in the context of elastohydrodynamic (EHD) lubrication. Various models addressing the origin and mechanism of liquid viscosity are reviewed. The derivation of viscosity as a thermodynamic property is also reviewed and its relevance to the current study is discussed. Consideration is also given to two commonly accepted yet contrasting models of EHD traction, resulting in one being adopted for this research. The relationship of molecular structure to film generation is examined experimentally by studying a number of single component fluids with widely varying chemical structures. It is shown that pressure-viscosity coefficients derived from film thickness are strongly related to the respective chemical “family” of the lubricant. EHD friction (traction) measurements are also made and analysed in order to establish a reliable method for comparing the influence of fluid composition on traction. The method, based on a well regarded fluid model, allows accurate description of full fluid traction by means of the Eyring stress and pressure-viscosity coefficient in the central EHD contact. Binary blends of well-defined base fluids are studied. It is found that the pressure- viscosity coefficient, as derived by the aforementioned methods, varies nonlinearly with the composition and tends toward the lower value of the individual components, at times attaining values lower than either of the individual components.

A high-traction fluid is one of the vital components of a traction drive; a mechanism where input power is transformed into an output force when pressure and shear force are applied to the fluid. In this environment they need to withstand high pressures, temperatures and shear forces, and must be able to lubricate at the same time. So far there has been very little research relating engineering performance to molecular structure. Previous work with model hydrocarbon traction fluids has shown that molecular rigidity about the centre of the molecule appears to be important. This work has now been extended to cyclohexyl esters. A series of cyclohexyl esters was synthesised, and where possible, x-ray structures were obtained. Extensive 13C T1 and NOE relaxation data over a range of radiofrequencies and temperatures were obtained and used to calculate correlation times, for both overall and internal motion, using both the "model-free" and reduced Lorentzian models. This provided information on the rigidity of the molecules studied, In addition molecules have been modelled using molecular dynamics techniques to calculate order parameters and torsion angle distributions. ESR studies have been conducted to measure the viscosity of each fluid. A spin probe, with a similar structure to one of the molecules studied, was synthesised. This allowed complimentary correlation time measurement, and showed that the molecule rotated isotropically. Difficulties were encountered in fitting the NMR data to the motional models and the need for higher radiofrequency data is indicated, to check the validity of the models used. The NMR, ESR and molecular dynamics results did, however, provide a consistent indication of the differing rigidities and motions of these molecules.

I. The seed of the tree Onguekoa Goro (Olacaceae) contains nine acetylanic C18 acids comprising three quarters of the total glyceride acids. Four of these acids also contain a hydroxyl group attached to C[sub](8). 8-hydroxyootadec-terns-11-on-9-ynoic aoid is isolated for the first ime from Santalum album seed oil. II. The stomach oil of the fulmar petrel (Fulmarus glacialis) is shown to be similar to a typical fish oil; acids containing 14-22 carbon atoms are present, including docosahoxaonoic and eicosapentaonoic acids. III. The classical method of analysis of the seed oils of the Umbelliferae was unsatisfactory and a more accurate method is now devised.

The isolation and structural identification of the minor components of cod liver oil was undertaken with particular attention to those of novel structure. A series of procedures based on urea crystallisation, argentation chromatography and preparative glc were developed for the isolation of the unusual acids present at low level. With these procedures, phytol-based acids (isoprenoids), furanoid acids and a series of mono-and diunsaturated branched-chain fatty acids were isolated. These fatty acids were characterised by a combination of mass spectrometry and nmr. In the case of the branched-chain acids, a GC-MS capillary system was used. Pyrrolidide and O-TMS derivatives of the acids were also studies for the location of double bonds. Three phytol-based acids were identified. In addition to confirming the presence of nine furanoid acids, new furanoid acids were also discovered. The discovery of a branched diunsaturated acid is significant. The 7,9 dimethylhexadec -6,8-dienoic acid is novel and is reported in this study for the first time. In addition to these acids, the major component acids of cod liver oil were isolated and identified. For the isolation of these, procedures such as low temperature crystallisation, argentation chromatography and preparative glc were adopted. Ozonolysis followed by reduction with triphenylphosphine was used for the analysis of the positional isomers of monoene acids. For diene acids ozonolysis was followed by reduction with sodium borohydride. The merits and demerits of these two procedures for the location of double bonds in a fatty acid chain are discussed. Oxymercuration-demercuration was used for the characterisation of some of the polyene acids. Only polyene acids having △3t, △4 or △5 unsaturation react in this procedure to furnish cyclic ethers which can be isolated and identified. The fragmentation characteristics of these cyclic ethers are discussed.

The reaction of nitric oxide (NO) with several organic and model biological compounds was studied to determine the ultimate fate of NO in a biological milieu, and to devise novel methods of trapping and analysing NO. A series of potential spin traps including anthracene, o-quinone and 2- acetylcyclohexanone was investigated by bubbling NO through a solution of the above compounds. The resulting mixture was analysed by EPR spectroscopy and GC-MS. The EPR spectra obtained showed no radicals were produced and GC-MS analysis revealed only unreacted starting material. Dienes were investigated because of their willingness to react with radical species. Trans-1,4-diphenyl-1,3-butadiene did not form a nitroxide when reacted with NO, but in the presence of molecular oxygen, 2,5-dimethyl-2,4-hexadiene gave a mixture of a di-t-alkyl nitroxide and a t-s-dialkyl nitroxide. Traps related to nitromethane anion were investigated in basic solution to generate the aci form, but the only compound to give a spin adduct was nitroethane, and this did not give the expected EPR spectrum. 2-Diazocycloheptanone was synthesised from cycloheptanone and reacted with NO. This reaction produced E and Z iminoxyl radicals and a carbonyl nitroxide. When the solvent was changed from t-butyl benzene to water, no reaction was observed. A known NO donor, S-nitroso-N-acetyl penicillamine (SNAP), was mixed with the spin trap and photolysed, but this did not produce a spin adduct. A second diazo compound, 5-diazouracil, was investigated, and this produced a radical species with complex but weak EPR spectra. Nitric oxide was reacted with stable free radicals to provide a quantitative spectrophotometric test for NO. Tetraphenylhydrazine was prepared which is in equilibrium with the diphenylaminyl radical in solution. The diphenylaminyl radical trapped NO and was detected by UV/vis spectroscopy, reaching a λ[sub]max after about one hour. When the solvent was changed from t-butyl benzene to acetonitrile, the reaction took place much more rapidly. From these results it appeared that NO could be detected at concentrations beteween 10 −4 and 10−7 M. Nitric oxide did not react with the parent compound, diphenylamine. When mixed with NO2, diphenylamine formed nitro addition products. Another stable radical, galvinoxyl, was investigated. This did not rapidly scavenge NO to give an identifiable adduct. Nitric oxide was reacted with several alkenes with electron-releasing groups and alkenes with electron-withdrawing groups. The reaction between n-butylvinyl ether and NO was investigated at room temperature. Many oxidation products were identified from the mass spectra obtained. Oxidation products were also identified from the reaction between NO and 1-cyclohexenyIoxytrimethylsilane. Analysis by EPR spectroscopy revealed the presence of two radicals, likely to be dialkyl nitroxides. No products were observed in the reaction of NO and methyl linoleate. EPR spectroscopy of a solution containing mesityl oxide and NO revealed the presence of three radicals, E and Z conformers of the iminoxyl radical, and a carbonyl nitroxide. 1-Acetylcyclohexene reacted with NO to give a di-t-alkyl nitroxide. Synthesis and subsequent photolysis of 1-acetylcyclohexenyl oxime confirmed this result. Another acceptor compound studied was tetracyanoethene; this did not react with NO. Cyclopropylacetyl peroxide was investigated, as decomposition gives the cyclopropyl methyl radical. Analysis of the resulting solution showed that bicyclohexyl had been formed, but there were no traces of any nitrogen-containing products. Nitric oxide did not react with either glutathione or dibenzyl disulphide, but NO2 reacted with L-tryptophan forming a radical adduct. Analysis by EPR spectroscopy yielded a strong three-line signal, characteristic of a nitroxide. The abstraction of hydrogen from, and the rearrangement of selected silylamines was investigated. The amines were photolysed in the presence of di-t-butyl peroxide in the cavity of the EPR spectrometer at temperatures ranging from 160K to 250K. The spectra obtained showed the unrearranged and rearranged radicals. No nitrogen-centred radicals were observed by EPR.