The application of Selected Ion Flow Tube Mass Spectrometry (SIFT MS) to the analysis of olive oil shows several distinct advantages over more conventional analysis techniques. The two areas described in this thesis examining olive oil quality are the analysis of Volatile Organic Compounds (VOCs) and the assessment of antioxidant activity. VOCs are responsible for the aroma and much of the taste of olive oil, while antioxidants afford some protection from harmful reactions involving radical species inside the body by scavenging radicals when olive oil is ingested. The VOCs of olive oil are used by sensory panel judges to classify oils by their degree of suitability for human consumption. The major parameters used for this evaluation are the strengths of any defects and the degree of fruitiness. A defect is an indication of an undesired process which has occurred in the oil, while fruitiness is a fragile attribute which denotes a good quality oil and is easily masked by defects. SIFT MS was used to measure the strengths of the olive oil defects rancid, winey, musty, fusty and muddy. Great potential was demonstrated for all defects except musty and the concentrations of VOCs in olive oil head space were correlated with the peroxide value, a measure of the degree of oil oxidation. A study aimed at correlating the strength of the fruitiness attribute as determined by a sensory panel with the concentrations of VOCs in olive oil head space was unsuccessful. The SIFT MS Total Oxyradical Scavenging Capacity (TOSC) assay was used to measure olive oil antioxidants. This assay measures all antioxidants in oil, not only those removed by extraction with a solvent, as it is conducted in an emulsion. SIFT MS TOSC assay results were found to correlate well with those of the widely used Folin Ciocalteu assay and the total concentration of phenolic compounds present in olive oil. Discrepancies between the two assays were most likely due to hydrophobic antioxidants which are measured by the SIFT MS TOSC assay but not the other tests.

Data is presented for a range of experiments that have been performed using a selected ion flow tube (SIFT) instrument operated at room temperature (~ 298K) with carrier gas pressures typically in the range of 0.3 – 0.6 Torr. The majority of the experiments discussed are performed on a Voice100 instrument that has not been described in detail previously. The Voice100 is a novel instrument that has been designed particularly for quantitative trace gas analysis using the SIFT-MS technique. A mixture of helium and argon carrier gases are employed in the Voice100 flow tube. By mixing carrier gases, the flow dynamics and diffusion characteristics of a flow tube are altered when compared to classic single carrier gas models. Therefore firstly, optimal flow conditions for the operation of a Voice100 are characterised. The diffusion of an ion in a mixture of carrier gases is then characterised using theoretical models and experimental techniques. This research requires that a new parameter Mp be defined regarding the mass discrimination of an ion in the non-field-free region near the downstream ion sampling orifice. Furthermore, a new method is described for the simultaneous measurement of rate coefficients for the reactions of H₃O⁺.(H₂O)n (n = 1, 2, 3) ions with analytes. Rate coefficients and branching ratios for the reactions of SIFT-MS precursor ions with specific analytes related to four individual applications are presented. For each application, the kinetic parameters are determined so as to facilitate the quantitative detection of the analytes relevant to that application. The GeoVOC application involves the measurement of hydrocarbon concentrations in the headspace of soil and water across a range of humidities. Alkyl esters are investigated to allow for the quantitative detection of each compound in fruits and vegetables. Chemical warfare agents, their surrogates and precursor compounds are studied which allows for the quantitative or semi-quantitative detection of a range of highly toxic compounds. Finally, 17 compounds classified by the US-EPA as hazardous air pollutants are studied that enables SIFT-MS instruments to replicate sections of the TO-14A and TO-15 methods.

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by MSHA and required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. The following research was performed in response to NIOSH’s call for the investigation into new refuge alternatives. A 15 psi safe haven polycarbonate wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics. The successful design was tested multiple times in both half-scale and small scale using a high explosive shock tube to determine the walls resistance to blast pressure. The safe haven wall design was modeled for an actual underground coal mine environment to determine any responses of the wall within a mine. A full scale design was fabricated and installed in an underground coal mine to determine any construction constraints and as a final step in proof of concept for the safe haven design.

A prerequisite for a functioning middle ear is an air-filled middle ear cavity. Aeration of the middle ear cavity is controlled by the Eustachian tube. Dysfunction of the Eustachian tube has long been acknowledged as a significant etiological factor in disorders of the middle ear, especially middle ear effusions. Artificial ventilation of the middle ear through the tympanic membrane has been practised for almost two centuries, but with varying degrees of success. In 1954, Armstrong reintroduced the method of inserting a transmyringeal tympanostomy tube into the ear drum. Since that time this ventilatory device has gained wide popularity and several types of tube have been designed. However, an increasing number of clinical reports have shown treatment with tympanostomy tubes to be followed by complications such as tympanosclerosis, atrophy, persistent perforations and cholesteatomas. In the present thesis, experiments were outlined in which the tympanostomy tube - tympanic membrane interaction was studied and in which tympanostomy tubes were also applied in a well-defined type of otitis media. Furthermore, alternative transmyringeal ventilatory procedures such as myringotomies with a delayed healing time were investigated. The results were evaluated with morphological and microbiological methods. Repeated tympanostomy tube insertions in ears of healthy rats caused a remarkable thickening (about 30-fold) of the tympanic membrane of the tubulated quadrants, but even the untouched quadrants were affected. The thickened areas were characterized mainly by an increase in dense connective tissue which also contained sclerotic plaques. The structural changes in the tympanic membrane were still present 3 months after the final ventilation episode. Cleavage of the rat soft palate caused an immediate accumulation of effusion material in the tympanic cavity due to disturbance of Eustachian tube function. The fluid turned purulent within one to two weeks. The microbial flora of the middle ear cavity correlated well with that of the nasopharynx, indicating an ascending infection. Insertion of a tympanostomy tube could prevent the accumulation of effusion material in the meso- and hypotympanon and significantly suppress bacterial growth in the middle ear cavity. Thermal energy-inflicted myringotomies were tested as an alternative method for establishing transmyringeal ventilation. Myringotomies performed either with a CCL-laser or by diathermy showed a delayed healing pattern, most probably due to widespread destruction of the outer keratinized squamous epithelium and damage to the vascular supply. Upon comparison, laser myringotomies appeared more favourable due to their longer closure times, whereas the perforations accomplished by diathermy were often complicated by otorrhea and showed more advanced structural changes. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1985, härtill 6 uppsatser.</p> / digitalisering@umu

Les tubes métalliques de précision sont largement utilisés pour des applications biomédicales. De tels tubes sont fabriqués par étirage à froid car ce procédé garanti le meilleur aspect de surface, le plus grand contrôle des dimensions du tube et le contrôle des propriétés mécaniques. L'objet de cette étude est de modéliser le procédé d'étirage de tube sur mandrin afin d'en améliorer la compréhension et de construire un outil permettant l'optimisation du procédé et de prédire la rupture des tubes en étirage. La construction du modèle élément finis s'appuie sur la réalisation d'essais expérimentaux afin de caractériser les propriétés mécaniques des matériaux et le frottement entre le tube et les outils d'étirage (mandrin, filière). Le comportement mécanique des alliages est caractérisé par des essais de traction sur tube, des essais de traction sur des éprouvettes découpées dans différentes orientations dans un tube déplié et des essais de gonflement de tube. Pour ces derniers, une machine et un outillage de gonflement de tubes ont été développés spécifiquement. Par le biais de ces essais différents aspects ont été étudiés : la viscoplasticité, l'anisotropie plastique, l'hétérogénéité des propriétés dans l'épaisseur du tube, la thermomécanique. Les coefficients de frottements ont été identifiés par analyse inverse sur des essais d'étirage instrumentés par des cellules d'effort. Des essais d'étirage ont été spécifiquement conçus en modifiant la géométrie du mandrin afin de conduire à la rupture des tubes lors de l'étirage. L'objectif de tels essais étant d'identifier la limite de formabilité des tubes. L'approche choisie pour prédire de la rupture a été d'utiliser des critères de ruptures qui pouvaient être calibrés sur des essais de traction uniquement. Les critères ont été calculés au cours de la simulation numérique de l'étirage sur mandrin et ils ont été évalués par rapport à leur capacité à prédire les réductions de section et d'épaisseur maximales. Enfin, des méthodes analytiques de calcul d'effort d'étirage ont été développées et comparées à la modélisation éléments finis.

Statement of problem: We have shown that the C677T 5,10 methylenetetrahydrofolate reductase (MTHFR) variant is associated with elevated maternal serum α-fetoprotein (MSAFP), the most common screening test for neural tube defects (NTD). Therefore, past contradictory studies of NTDs and C677T MTHFR may have been biased because of changes in case populations after prenatal diagnosis and termination of pregnancy. Further, an unexplained elevation of MSAFP is known to increase the risk for later pregnancy complications. Is the C677T MTHFR variant a predisposing genetic variant for both NTDs and later complications of pregnancy? Methods: A retrospective study of women with pregnancies resulting in NTD outcome and women with unexplained elevations of MSAFP was undertaken. Women and their partners were genotyped for the C677T MTHFR allele. Couples with a pregnancy resulting in a NTD outcome were compared to couples whose pregnancy outcome did not involve. Couples with unexplained elevations of MSAFP who did and did not have later complications of pregnancy were also compared. Allele frequencies for all groups were then compared against the previously established Manitoba population allele frequency (based on 977 consecutive newborn metabolic screening bloodspots). A review of all studies of NTDs and association with the C677T MTHFR variant was undertaken to determine if the association between the variant and MSAFP is a source of bias. NTD incidence was examined before and after folic acid food fortification introduced in Canada in 1999. Results: There is an increase in the allele frequency of the C677T MTHFR variant in parents with an unexplained elevated MSAFP followed by later complications of pregnancy. The C677T MTHFR variant is also a contributing genetic factor to NTDs worldwide. The incidence of NTDs in Manitoba has decreased by 37% since food fortification with folic acid was introduced. Conclusions: The C677T MTHFR variant is a contributing genetic factor to both later complications of pregnancy after an unexplained elevation of MSAFP and to NTDs. This variant is folate sensitive and folic acid fortification has reduced the incidence of NTDs.

Previous data in our lab demonstrated an inability to induce oral tolerance when using a feeding needle gavage for 14 days. Given that the upper gastrointestinal (GI) tract is the site of antigen introduction, and the interplay between immune cells of the mucosal tissues, we questioned if inflammation in this tissue, induced by physical trauma, would affect oral tolerance induction. We performed studies on Balb/c mice using a needle gavage or syringe feeding method followed by doses of the immunogenic protein ovalbumin (OVA) to induce tolerance. Immunohistochemistry was used to assess inflammation in esophageal tissues and to correlate with an ability or inability to induce tolerance. Non-cellular alterations within the tissue were also assessed using a pathology grading score. Although fluctuations in cell populations were observed in both the syringe and gavage treated mice, the needle gavage caused significant noncellular damage to esophageal mucosal tissue, which is the most likely cause of failed tolerance induction to the OVA. / Department of Biology

The steam generator plays a primary role in the safety and performance of a pressurized water reactor nuclear power plant. The cost to utilities is in the order of millions of Rands a year as a direct result of damage to steam generators. The damage results in lower efficiency or even plant shutdown. It is necessary for the utility and for academia to have models of nuclear components by which research and analysis may be performed. It must be possible to analyse steam generator performance for both day-to-day operational analysis as well as in the case of extreme accident scenarios. The homogeneous model for two-phase flow is simpler in its implementation than the two-fluid model, and therefore suffers in accuracy. Its advantage lies in its quick turnover time for development of models and subsequent analysis. It is often beneficial for a modeller to be able to quickly set up and analyse a model of a system, and a trade-off between accuracy and time-management is thus required. Searches through available literature failed to provide answers to how the homogeneous model compares with the two-fluid model for operational and safety analysis. It is expected to see variations between the models, from the analysis of the mathematics, but it remains to be shown what these differences are. The purpose of this study was to determine how the homogeneous model for two-phase flow compares with the two-fluid model when applied to a u-tube steam generator of a typical pressurized water reactor. The steam generator was modelled in both RELAP5 and in Flownex. A custom script was written for Flownex in order to implement the Chen correlation for boiling heat transfer. This was significantly less detailed than RELAP5’s solution of a matrix of flow regimes and heat transfer correlations. The geometry of the models were based on technical drawings from Koeberg Nuclear Power Plant, and were simplified to a one-dimensional model. Plant data obtained from Koeberg was used to validate the models at 100%, 80% and 60% power output. It was found that the overall heat transfer rate predicted with the RELAP5 two-fluid model was within 1.5% of the measured data from the Koeberg plant. The results generated by the homogeneous model for the overall heat transfer were within 4.5% of the measured values. However, the differences in the detailed temperature distributions and heat transfer coefficient values were quite significant at the inlet and outlet ends of the tube bundle, at the bottom tube sheet of the steam generator. In this area the water-level was not accurately modelled by the homogeneous model, and therefore there was an under-prediction in heat transfer in that region. Large differences arose between the Flownex and RELAP5 solutions due to difference in the heat transfer correlations used. The Flownex model exclusively implemented the Chen correlation, while RELAP5 implements a flow regime map correlated to a table of heat transfer correlations. It was concluded that the results from the homogeneous model for two-phase flow do not differ significantly when compared with the two-fluid model when applied to the u-tube steam generator at the normal operating conditions. Significant differences do, however, occur in lower regions of the boiler where the quality is lower. We conclude that the homogeneous model offers significant advantage in simplicity over the two-fluid model for normal operational analysis. This may not be the case for detailed accident analysis, which was beyond the scope of this study. / Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.

The steam generator plays a primary role in the safety and performance of a pressurized water reactor nuclear power plant. The cost to utilities is in the order of millions of Rands a year as a direct result of damage to steam generators. The damage results in lower efficiency or even plant shutdown. It is necessary for the utility and for academia to have models of nuclear components by which research and analysis may be performed. It must be possible to analyse steam generator performance for both day-to-day operational analysis as well as in the case of extreme accident scenarios. The homogeneous model for two-phase flow is simpler in its implementation than the two-fluid model, and therefore suffers in accuracy. Its advantage lies in its quick turnover time for development of models and subsequent analysis. It is often beneficial for a modeller to be able to quickly set up and analyse a model of a system, and a trade-off between accuracy and time-management is thus required. Searches through available literature failed to provide answers to how the homogeneous model compares with the two-fluid model for operational and safety analysis. It is expected to see variations between the models, from the analysis of the mathematics, but it remains to be shown what these differences are. The purpose of this study was to determine how the homogeneous model for two-phase flow compares with the two-fluid model when applied to a u-tube steam generator of a typical pressurized water reactor. The steam generator was modelled in both RELAP5 and in Flownex. A custom script was written for Flownex in order to implement the Chen correlation for boiling heat transfer. This was significantly less detailed than RELAP5’s solution of a matrix of flow regimes and heat transfer correlations. The geometry of the models were based on technical drawings from Koeberg Nuclear Power Plant, and were simplified to a one-dimensional model. Plant data obtained from Koeberg was used to validate the models at 100%, 80% and 60% power output. It was found that the overall heat transfer rate predicted with the RELAP5 two-fluid model was within 1.5% of the measured data from the Koeberg plant. The results generated by the homogeneous model for the overall heat transfer were within 4.5% of the measured values. However, the differences in the detailed temperature distributions and heat transfer coefficient values were quite significant at the inlet and outlet ends of the tube bundle, at the bottom tube sheet of the steam generator. In this area the water-level was not accurately modelled by the homogeneous model, and therefore there was an under-prediction in heat transfer in that region. Large differences arose between the Flownex and RELAP5 solutions due to difference in the heat transfer correlations used. The Flownex model exclusively implemented the Chen correlation, while RELAP5 implements a flow regime map correlated to a table of heat transfer correlations. It was concluded that the results from the homogeneous model for two-phase flow do not differ significantly when compared with the two-fluid model when applied to the u-tube steam generator at the normal operating conditions. Significant differences do, however, occur in lower regions of the boiler where the quality is lower. We conclude that the homogeneous model offers significant advantage in simplicity over the two-fluid model for normal operational analysis. This may not be the case for detailed accident analysis, which was beyond the scope of this study. / Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.

This report contains an investigation of fluid injection techniques used in the purpose of reducing deleterious flow effects occurring in the draft tube of Francis turbines when operating outside nominal load. There is a focus on implement ability at Jämtkrafts hydroelectric power plants and two power plants were investigated, located in series with each other named Lövhöjden and Ålviken. The only profitable scenario found with some degree of certainty was an increase in the operating range upwards to allow overload operation. Findings show that both air and water can be introduced in various locations to improve hydraulic efficiency around the turbine parts as well as reduce pressure pulsations in harmful operating regions. Investments in such systems have proven useful and profitable at several facilities with poorly adapted operating conditions. But due to losses in efficiency when operating injection systems, it turns out unprofitable in situations where it does not improve the operating range in a way that is resulting in increased annual or peak production.