Thesis (MSc)--University of Stellenbosch, 2007. / Bibliography.

Thesis (M.A. Sc.)--University of Ottawa, 2003. / Includes bibliographical references. Abstract and 24 page preview available online.

Thesis (M. A. Sc.)--University of Toronto, 2003. / Includes bibliographical references (p. 76-80 of photocopy). Abstract and 24 page preview available online.

The deterioration of electrical insulating oils results in the formation of complex oxidation products, many of which are polar in structure. The significance of the microwave-frequency dielectric-loss measurement, when applied to the evaluation of aged transformer oils, is investigated. A cylindrical cavity, operating in the TE₀₁ mode, is used to measure the loss tangent of aged transformer oils. Q-factor measurements are made by a dynamic method which is described. The problem of mode interference in the cavity is investigated in detail. It is found that the loss tangent of transformer oils, measured at X-band, increases as the oil deteriorates through oxidation. The increase is influenced by several factors but closely parallels the increase in acidity. Sludge particles do not in themselves cause a significant increase in the dielectric losses. An indirect correlation between the loss tangent and the sludge content of an oil may exist but has not been established. The change in the dielectric constant of an oil caused by the presence of dissolved water, or by the ageing process, is too small to be measured by the method used. A small but measureable increase in the loss tangent is produced by the presence of water in concentrations of approximately 75 parts per million. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Environmental concern and the possibility of energy shortages have drawn attention to means for recovering material and energy resources from waste products. The focus of this thesis is on the application of cost-benefit analysis as a methodological technique for evaluating the economics of resource recovery: namely used lubrication oil. The study initially focuses on the general concern of the economics of resource recovery. This is undertaken primarily by a review of existing literature. An investigation of cost-benefit analysis as advanced by Pearce, Pearce and Dasgupta, Canadian Treasury Board Secretariat, Winch, Nath, Anderson, and Settle, to name a few, reveal a comprehensive and systematic framework for the evaluation of public investment alternatives. Items for inclusion in the analysis are all costs and benefits to every member of, a defined society whose welfare would be affected by the project if implemented. Many goods and services do not enter into the market system, causing difficulty in deriving monetary values for some of the components, especially environmental concerns. For example, the case study reveals two areas: 1) benefit of pollution abatement stemming from resource recovery of used lubrication oil, and 2) costs associated with the improper disposal of the waste products from the recycling process of used lubrication oil. An attempt is made to apply the cost-benefit framework to the case of lubrication oil recycling in the province of British Columbia. Adequate quantitative data were not available, particularly on the social costs and benefits, to fully employ the cost-benefit technique, therefore restricting the analysis in that only an identification of costs and benefits was prepared. When quantification of costs and benefits is not possible, a detailed description of the unquantifiable items indicates to the decision maker the extent of the components. Included in this study is a presentation of the environmental impacts of used oil disposal. The limitations of the cost-benefit analysis as an evaluation technique arise because of limited information and data needed to evaluate, in monetary terms, environmental improvement. Future research could involve a "simulation" of the market to determine a plausible shadow price that gives an indication of what the market price of the item would have been if it had been normally traded. A determination of the price that consumers would be willing to pay for the benefits of pollution control with the knowledge that some pollution would be produced by the recycling activity would aid the analyst in placing values on the costs and benefits. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

Understanding of molecular events involved in food safety and human health has become a major concern of contemporary life. Mass spectrometry (MS) is a powerful tool for characterization of complex food ingredients and biological molecules. Advances in MS-based techniques have offered new opportunities to understand the chemical changes occurring during food storage and processing as well as the molecular events perturbed by either endogenous or exogenous stimulus. In this thesis, we developed novel MS-based approaches for authentication of edible oil (i.e., edible vegetable oil, deep frying oil and gutter oil), assessment of genotoxicity of fatty acid hydroperoxides, and investigation of metabolic deregulation in pleural effusion and tissue of human lung cancer, aiming to gain a better understanding of food safety and human health. MS-based methods were developed for authentication of edible vegetable oil adulterated with used cooking oil. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that six monoglycerides could be used as the markers to discriminate the used cooking oil (e.g., deep frying oil and gutter oil) and qualified edible oil. Accumulation behavior of these six monoglycerides was detected in the repeatedly heated edible oils. Quantitation of the monoglycerides enabled authentication of commercial olive oil adulterated with a small amount of used cooking oil (approximately 1%). In addition, a matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) method was developed for visual authentication of edible oil samples, including commercial vegetable oil, used cooking oil and adulterated edible oil. The method provided the capability for quantifying major chemical composition of edible oil, such as triglycerides, diglycerides and monoglycerides. The present method required minimal sample preparation and allowed screening of oil samples with high throughput (approximately 360 samples per day), providing a simple way to authenticate different types of oil samples. Liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) was applied to investigate the genotoxicity of two fatty acid hydroperoxides, i.e., 13-hydroperoxyoctadeca-cis-9,trans-11-dienoic acid (13-HPODE) and 13-hydroperoxy-9,11E,15Z-octadecatrienoic acid (13-HPOTE), which are important inducers of oxidative deterioration in oils and fats generated from the oxidation of linolenic acid and linoleic acid. The results demonstrated that the α,β-unsaturated aldehydes, such as 4-oxo-2-nonenal, dioxo-10-dodecenoic acid, 4-hydroperoxy-2-nonenal and 4-hydroxy-2-nonenal are the main degradation compounds of 13-HPODE and 13-HPOTE, which can covalently bound to deoxyribose-nucleosides and ribose-nucleosides to form adducts. This study provided evidences regarding the genotoxicity of fatty acid hydroperoxides at the molecular level. MS-based metabolomics methods were developed and applied for the investigation of metabolic signatures of pleural effusion and tissue of human lung cancer. A database-assisted global metabolomics method was established with utility of LC-Orbitrap MS, followed by automated mass spectral searching. The method enabled unbiased identification of 194 endogenous metabolites in pleural effusions caused by tuberculosis and malignancy. Among which, 33 differential metabolites involved in tryptophan catabolism, bile acid biosynthesis, and β-oxidation of fatty acids were found between tuberculous and malignant pleural effusions, which provided non-invasive biomarkers for diagnosis of pleural effusion samples with high sensitivity and specificity. In addition, a large-scale targeted metabolomics method was developed, which enabled reliable detection of over 400 biological metabolites, covering 92 metabolic pathways in human samples. The method was applied to characterize the metabolic profiles of non-small cell lung cancer (NSCLC) tissues. A number of distant metabolic pathways were found to be differentiated between tumor and normal tissues of lung squamous cell carcinoma and adenocarcinoma, including purine metabolism, citric acid cycle, amino acid metabolism, urea cycle, and ammonia recycling. In addition, several metabolites, such as adenosine, glutamate, glucose 1,6-bisphosphate, betaine, creatine and methionine sulfoxide were found to be associated with prognosis of NSCLC patients, which might provide potential biomarkers to monitor metabolic characteristics of NSCLC patients and treatment outcomes of the cancer.

Understanding of molecular events involved in food safety and human health has become a major concern of contemporary life. Mass spectrometry (MS) is a powerful tool for characterization of complex food ingredients and biological molecules. Advances in MS-based techniques have offered new opportunities to understand the chemical changes occurring during food storage and processing as well as the molecular events perturbed by either endogenous or exogenous stimulus. In this thesis, we developed novel MS-based approaches for authentication of edible oil (i.e., edible vegetable oil, deep frying oil and gutter oil), assessment of genotoxicity of fatty acid hydroperoxides, and investigation of metabolic deregulation in pleural effusion and tissue of human lung cancer, aiming to gain a better understanding of food safety and human health. MS-based methods were developed for authentication of edible vegetable oil adulterated with used cooking oil. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that six monoglycerides could be used as the markers to discriminate the used cooking oil (e.g., deep frying oil and gutter oil) and qualified edible oil. Accumulation behavior of these six monoglycerides was detected in the repeatedly heated edible oils. Quantitation of the monoglycerides enabled authentication of commercial olive oil adulterated with a small amount of used cooking oil (approximately 1%). In addition, a matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) method was developed for visual authentication of edible oil samples, including commercial vegetable oil, used cooking oil and adulterated edible oil. The method provided the capability for quantifying major chemical composition of edible oil, such as triglycerides, diglycerides and monoglycerides. The present method required minimal sample preparation and allowed screening of oil samples with high throughput (approximately 360 samples per day), providing a simple way to authenticate different types of oil samples. Liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) was applied to investigate the genotoxicity of two fatty acid hydroperoxides, i.e., 13-hydroperoxyoctadeca-cis-9,trans-11-dienoic acid (13-HPODE) and 13-hydroperoxy-9,11E,15Z-octadecatrienoic acid (13-HPOTE), which are important inducers of oxidative deterioration in oils and fats generated from the oxidation of linolenic acid and linoleic acid. The results demonstrated that the α,β-unsaturated aldehydes, such as 4-oxo-2-nonenal, dioxo-10-dodecenoic acid, 4-hydroperoxy-2-nonenal and 4-hydroxy-2-nonenal are the main degradation compounds of 13-HPODE and 13-HPOTE, which can covalently bound to deoxyribose-nucleosides and ribose-nucleosides to form adducts. This study provided evidences regarding the genotoxicity of fatty acid hydroperoxides at the molecular level. MS-based metabolomics methods were developed and applied for the investigation of metabolic signatures of pleural effusion and tissue of human lung cancer. A database-assisted global metabolomics method was established with utility of LC-Orbitrap MS, followed by automated mass spectral searching. The method enabled unbiased identification of 194 endogenous metabolites in pleural effusions caused by tuberculosis and malignancy. Among which, 33 differential metabolites involved in tryptophan catabolism, bile acid biosynthesis, and β-oxidation of fatty acids were found between tuberculous and malignant pleural effusions, which provided non-invasive biomarkers for diagnosis of pleural effusion samples with high sensitivity and specificity. In addition, a large-scale targeted metabolomics method was developed, which enabled reliable detection of over 400 biological metabolites, covering 92 metabolic pathways in human samples. The method was applied to characterize the metabolic profiles of non-small cell lung cancer (NSCLC) tissues. A number of distant metabolic pathways were found to be differentiated between tumor and normal tissues of lung squamous cell carcinoma and adenocarcinoma, including purine metabolism, citric acid cycle, amino acid metabolism, urea cycle, and ammonia recycling. In addition, several metabolites, such as adenosine, glutamate, glucose 1,6-bisphosphate, betaine, creatine and methionine sulfoxide were found to be associated with prognosis of NSCLC patients, which might provide potential biomarkers to monitor metabolic characteristics of NSCLC patients and treatment outcomes of the cancer.

Effects of different weed control practices on soil quality in mediterranean crops This research approaches the question of weed control sustainability, from the point of view of soil quality maintenance and enhancing. A big choice of practices and products for weed control are available nowadays, but the actual definition of "sustainable practice" not always considers soil fertility. Soil processes timescale is wider than the productive, commercial and legislative ones. Also the definition of survey protocols is a process slower than the evolution of weed control methods. The faster reaction in the soil ecosystem after an external pressure is given by the organisms living in it, and the microbial community is finally the most effective agent in nutrient recycling processes. In this investigation, the same soil analysis protocol was applied on soil samples exposed to different weed management and control methods. Using soil quality indexes and bioindicators, soil properties variations after the different weed control treatments were compared. In particular soil carbon pool and how microbial community recycles was surveyed. A standard protocol to both find variations in long-term soil quality and survey the short-term impact of weed control practices on soil biological processes was defined. Weed management practices can interact with the nutrients recycling processes performed by the microorganisms living in the soil. These processes have a central role in maintaining soil fertility, one of the most important resources for agriculture. Three weed management practices were compared: the use of synthetic (oxyfluorfen) or natural (essential oils and aqueous extracts) herbicides and two mechanical methods (tillage and mulching). Soil fertility was monitored measuring soil physical-chemical values and elaborating soil quality indexes and bioindicators. / Efectos de diferentes prácticas de control de arvenses sobre la calidad del suelo en cultivos mediterráneos Esta investigación aborda la cuestión de la sostenibilidad del control de las plantas arvenses, desde el punto de vista del mantenimiento y mejora de la calidad del suelo. Una gran variedad de prácticas y productos para el control de las arvenses están disponibles hoy en día, pero la definición real de "práctica sostenible" no siempre considera la fertilidad del suelo. La escala de tiempo de los procesos del suelo es más amplia que los procesos productivos, comerciales y legislativos. También la definición de protocolos para la investigación es un proceso más lento que la evolución comercial de los métodos de control de malas hierbas. La reacción más rápida en el ecosistema del suelo después de una presión externa es dada por los organismos que viven en ella, y la comunidad microbiana es el agente más eficaz en los procesos de reciclaje de nutrientes. En esta investigación se aplicó el mismo protocolo de análisis de suelo en muestras de suelo expuestas a diferentes métodos de manejo y control de arvenses. Utilizando índices de calidad del suelo y bioindicadores, se compararon las variaciones de propiedades del suelo después de los diferentes tratamientos de control de arvenses. En particular se estudiaron la reserva de carbono en el suelo y la forma en que la comunidad microbiana recicla. Se definió un protocolo estándar para encontrar variaciones en la calidad del suelo a largo plazo y para analizar el impacto a corto plazo de las prácticas de control de arvenses en los procesos biológicos del suelo. Las prácticas de manejo de malas hierbas pueden interactuar con los procesos de reciclaje de nutrientes realizados por los microorganismos que viven en el suelo. Estos procesos tienen un papel central en el mantenimiento de la fertilidad del suelo, uno de los recursos más importantes para la agricultura. Se compararon las prácticas de manejo de arvenses de frutales: el uso de herbicidas sintéticos (oxyfluorfen) o naturales (aceites esenciales y extractos acuosos) y dos métodos mecánicos (labranza y mulching). Se monitoreó la fertilidad del suelo midiendo los valores físico-químicos del suelo y elaborando índices de calidad del suelo y bioindicadores. / Efectes de diferents pràctiques de control d'arvenses sobre la qualitat del sòl en cultures mediterrànies Aquesta investigació aborda la qüestió de la sostenibilitat del control de les plantes arvenses, des del punt de vista del manteniment i millora de la qualitat del sòl. Una gran varietat de pràctiques i productes per al control de les arvenses estan disponibles avui en dia, però la definició real de "pràctica sostenible" no sempre considera la fertilitat del sòl. L'escala de temps dels processos del sòl és més àmplia que els processos productius, comercials i legislatius. També la definició de protocols per a la investigació és un procés més lent que l'evolució comercial dels mètodes de control de males herbes. La reacció més ràpida en l'ecosistema del sòl després d'una pressió externa és donada pels organismes que hi viuen, i la comunitat microbiana és l'agent més eficaç en els processos de reciclatge de nutrients. En aquesta investigació es va aplicar el mateix protocol d'anàlisi de sòl en mostres de sòl exposades a diferents mètodes de maneig i control d'arvenses. Utilitzant índexs de qualitat del sòl i bioindicadors, es van comparar les variacions de propietats del sòl després dels diferents tractaments de control d'arvenses. En particular es van estudiar la reserva de carboni en el sòl i la forma en què la comunitat microbiana el recicla. Es va definir un protocol estàndard per trobar variacions en la qualitat del sòl a llarg termini i per analitzar l'impacte a curt termini de les pràctiques de control d'arvenses en els processos biològics del sòl. Les pràctiques de maneig de males herbes poden interactuar amb els processos de reciclatge de nutrients realitzats pels microorganismes que viuen a terra. Aquests processos tenen un paper central en el manteniment de la fertilitat del sòl, un dels recursos més importants per a l'agricultura. Es van comparar les pràctiques de maneig d'arvenses de fruiters: l'ús d'herbicides sintètics (oxyfluorfè) o naturals (olis essencials i extractes aquosos) i dos mètodes mecànics (conreu i mulching). Es va monitorejar la fertilitat del sòl mesurant els valors fisicoquímics del sòl i elaborant índexs de qualitat del sòl i bioindicadors. / Oddo, M. (2017). Effects of different weed control practices on soil quality in Mediterranean crops [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90655

A major problem faced by the petroleum industry is the deposition of wax during the pumping of waxy crude oils. This precipitation occurs at “normal” temperature, typically 20-30°C in Libya. It could occur during the journey from well to terminal through hundreds of miles of pipelines. This kind of transportation is expensive in terms of pumping costs. The pumping has to be continuous; otherwise wax can build up in the pipeline, reducing the pumping or even stopping it. The property that defines this characteristic is the yield stress which depends on wax concentration and cooling rate. The build-up of paraffin and asphaltenes can lead to serious problems in formation, tanks, and pipelines. Blockages can be expensive and time-consuming to deal with; this is precisely the topic of this research. For this research, model and real waxy crude oils are formulated and their rheology systematically measured under various cooling rates to determine the yield stress. A pipeline loop has been designed to measure the start-up pressure of stagnant oil which has been allowed to precipitate wax. The start-up pressure and the thickness of deposited wax are used in a simple mathematical model to calculate the yield stress. This research thus provides two independent means of predicting the yield stress. This research studied three different waxy crude oils. An MCR-301 Anton Paar rheometer was used to measure the rheology of the oils, and a pipeline rig was used to obtain the start-up pressure to calculate the yield stress of each type of oil after different stoppage times. Also, the thickness of the precipitated wax is measured to calculate the yield stress precisely. The data show that the layer thickness has significant effect on the yield stress and start-up pressures and corresponding yield flow stresses have been found to underpin the crystallisation process of the wax and slow cooling rate produce stronger structures requiring higher stresses to fracture and induce flow. Also, longer shutdown times make these structures even stronger and therefore require even larger stresses for flow to commence.

By virtue of their fragrance and therapeutic nature, essential oils have gained great application in the cosmetic and pharmaceutical industries. These oils, as products consumed by the public for the general health and cosmetics, should be of high quality and unadulterated. In this project comprehensive two-dimensional gas chromatography (GCxGC) was used for the qualitative analysis of some South African essential oils. The main purpose of the project was to evaluate GCxGC for identification of essential oil constituents and for fingerprinting the different essential oils for quality control purposes. Essential oils of the same kind but of different origin were compared and the quantitative variation between their components was studied. Gas chromatography-time-of flight mass spectrometry (GC-TOFMS) as well as comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS) was used to help identify component peaks separated in the GCxGC instrument. Once certain precautions are taken and the delicate modulator is correctly optimized, the GCxGC results are reproducible and easy to interpret. Overall, the GCxGC technique utilized showed good promise for quality control of essential oils. / Dissertation (MSc)--University of Pretoria, 2006. / Chemistry / unrestricted