Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The Pebble Bed Modular Reactor (PBMR) is a Generation IV graphite-moderated helium cooled nuclear reactor which is being developed in South Africa. The PBMR design is based on the German Arbeitsgemeinschaft Versuchreaktor (AVR). The AVR was decommissioned in December 1988 due to operational and safety problems. The PBMR project has put a lot of emphasis on safety and therefore all safety issues relating to the AVR have to be addressed before this technology can be implemented. After the decommissioning of the AVR plant, technicians found radioactive isotopes of cesium 55Cs137, 55Cs134, silver 44Ag110 and strontium 38Sr90 as well as graphite dust in the primary coolant loop of the reactor. These isotopes as well as the graphite dust have to be removed from the helium coolant stream because it can be potentially harmful to equipment, personnel and the general public. The main objective of this thesis is therefore to investigate a separation method for removing the graphite dust (and with it the radioactive isotopes) from the helium coolant stream and also test this method under different operating conditions and geometrical configurations to determine its dust separation efficacy. The device chosen to investigate is the Ranque-Hilsch vortex tube. The Ranque-Hilsch vortex tube (RHVT) is a simple device having no moving parts that produces a hot and cold air stream simultaneously at its two ends from a compressed air source. The vortex generated by the vortex generator located at the inlet of the RHVT causes strongly rotating flows similar in speed to that of a gas centrifuge. The gas centrifuge is used for isotope separation. The RHVT, in theory, can therefore be implemented to separate the graphite/silver isotopes from the helium coolant with the added benefit of either cooling or heating the coolant and was thus selected as the separation technique to be tested experimentally. The dust separation efficiency of the RHVT was tested experimentally using different grades of graphite dust, different fluids, various inlet volumetric flow rates and volume fractions and different RHVT geometries. The experimental results showed that the RHVT has a dust separation efficiency of more than 85 %. A regression analysis was also done with the experimental data to obtain a correlation between the different operating conditions (such as volumetric flow rate) and the dust separation efficiency that can be used to predict the dust efficiency under different operating and geometric conditions (such as the PBMR environment). An analytical model is also presented to describe the ‘temperature separation’ phenomenon in the RHVT, using basic thermo-physical principals to gain a better understanding of how the RHVT works. A CFD analysis was also attempted to supplement the analytical analysis but the solution did not converge and therefore only the preliminary results of the analysis are discussed. / AFRIKAANSE OPSOMMING: Die “Pebble Bed Modular Reactor” (PBMR) is `n vierde generasie grafiet gemodereede en helium verkoelde reaktor wat in Suid-Afrika ontwikkel word. Die PBMR ontwerp is gebaseer op the Duitse Arbeitsgemeinschaft Versuchreaktor (AVR) wat buite werking gestel is in Desember 1988 as gevolg van operasionele en veiligheidsprobleme. Die PBMR projek lê baie klem op veiligheid en daarom moet alle veiligheidskwessies van die AVR eers aangespreek word voor die tegnologie geimplementeer kan word. Nadat die AVR buite werking gestel is, het AVR tegnisie radioaktiewe isotope van cesium 55Cs137, 55Cs134, silwer 44Ag110 en strontium 38Sr90 asook grafiet stof in die primêre stroomkring van die reaktor gevind. Hierdie isotope sowel as die grafiet stof moet uit die helium verkoelingsmiddel in die primere stroomkring van die reaktor verwyder word aangesien dit dalk skadelik kan wees vir toerusting, personeel en die publiek. Die hoofdoelwit van hierdie tesis is dus om `n skeidingstekniek te ondersoek wat die stof (en dus ook die radioaktiewe isotope) uit die helium verkoelingsmiddel kan verwyder. Hierdie tegniek moet dan getoets word onder verskillende operasionele en geometriese toestande om die skeidingsbenuttingsgraad te bepaal. Die toestel wat gekies is om ondersoek te word is die “Ranque-Hilsch Vortex Tube”. Die “Ranque-Hisch Vortex Tube” (RHVT) is a eenvoudige uitvindsel wat geen bewegende parte bevat nie en wat warm en koue lug gelyktydig produseer vanaf `n saamgepersde lugbron. ‘n Baie sterk roteerende vloei word gegenereer in die RHVT wat dieselfde snelhede bereik as die lug in `n gas-sentrifugeerder. Die gas- sentrifugeerder word gebruik as `n isotoopskeidingsapparaat. In teorie kan die RHVT dus ook gebruik word om partikels te skei as gevolg van die sterk roteerende vloei, met die voordeel dat dit ook die lug kan verhit en verkoel. As gevolg van hierde redes is die RHVT gekies as die skeidingstegniek om te ondersoek en dus experimenteel te toets. Die benuttingsgraad van die RHVT se vermoë om die grafiet stof van die lug te skei was gevolglik eksperimenteel getoets deur gebruik te maak van verskillende gehaltes grafiet stof, verskillende vloeistowwe (lug of helium), verskillende inlaat volumevloeitempos en volume fraksies en RHVT geometrieë. Die experimentele resultate het getoon dat die RHVT `n benuttingsgraad van meer as 85 % het. `n Regressie analise was ook gedoen met die eksperimentele data om `n korrelasie tussen die verskillende opersionele toestande (soos volumevloeitempo) en die stof skeiding benuttingsgraad te kry. Hierdie korrelasie kan dan gebruik word om die stofskeidingsbenuttingsgraad onder ander operasionele en geometriese omstandighede, soos die PBMR omgewing, te voorspel. `n Analitiese model word ook voorgestel om die “temperatuur-skeidings” meganisme in die RHVT te verduidelik, met die hulp van basiese termo-fisiese beginsels, om beter te verstaan hoe dit werk. Daar was ook gepoog om `n CFD analise te doen wat die analitiese model kon aanvul, maar die numeriese oplossing het nie gekonvergeer nie en dus word net die voorlopige resultate van dié analise bespreek.

Low-temperature magnetic force microscopy was used to study the phase diagram of a La1/3Pr1/3Ca1/3MnO3 thin film grown on a (110) NdGaO3 (NGO) substrate by pulsed laser deposition. Traditionally, one can observe the phase change at the nanoscale level as the sample is cooled from room temperature through the transition temperature to liquid nitrogen temperatures, but in this case a fixed voltage ranging from 0 V to 31 V was applied before each cooling cycle. From in and ex situ transport measurements, it is observed that the temperature of the peak of the transition increases with applied field; however, the MFM images show that the magnetic transition begins at a lower temperature with the same increase in field. Thus, this dissertation shows that a new voltage control exists for the phase transition in certain manganites. / text

The teratogenic effects of valproic acid (VPA) are well known, though its teratogenic mechanism remains unknown. VPA induces oxidative stress, which may lead to double strand breaks (DSBs) in DNA. Though the cell may repair this damage via homologous recombination (HR) and non-homologous end joining (NHEJ), repair is not always error-free; genomic instability may arise from gene deletions, amplifications, rearrangements, and loss of heterozygosity. Such alterations may underpin VPAʼs teratogenicity. The present study evaluated VPAʼs ability to induce NHEJ and HR and characterized the changes in expression of two proteins key to HR (RAD51) and NHEJ (XRCC4). Using pKZ1 transgenic mice (C57BL/6 genetic background), we sought to measure NHEJ events via X-gal staining. Although consistent staining was observed in adult male brain (positive control), no staining was observed in embryos 12 or 24 hours after in utero exposure to a teratogenic dose of VPA (500 mg/kg, maternal subcutaneous dose) on gestational day 9 (GD9). To determine whether the lack of staining observed in embryos was due to low/absent expression of key DSB-repair proteins, we measured mRNA/protein expression of RAD51 and XRCC4 in C57BL/6, GD9-exposed embryos and maternal brain. One hour after treatment, XRCC4 was increased at the protein level in brain and embryo. RAD51 was not increased in embryos and not detected in adult brain. These data suggest that embryos do possess the protein mediators of NHEJ and HR and that VPA-induced changes in expression of XRCC4 may influence the type of repair pursued, potentially affecting DSB repair fidelity (accuracy). Determination of fidelity of VPA-induced HR was attempted with the Chinese hamster ovary cell line (CHO33) using DNA sequencing; low template concentration and purity precluded successful sequencing of DNA from recombinant colonies and the assessment of fidelity. Overall, these data demonstrate that the lack of X-gal staining observed in pKZ1 embryos is not due to an underexpression of at least one key protein in the NHEJ pathway. Furthermore, a VPA-induced change in the the type of repair pathway pursued by the embryo may have teratological implications. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2012-10-15 11:06:30.613

Optical imaging methods have the potential to detect ovarian cancer at an early, curable stage. Optical imaging has the disadvantage that high resolution techniques require access to the tissue of interest, but miniature endoscopes that traverse the natural orifice of the reproductive tract, or access the ovaries and fallopian tubes through a small incision in the vagina wall, can provide a minimally-invasive solution. We have imaged both rodent and human ovaries and fallopian tubes with a variety of endoscope-compatible modalities. The recent development of fiber-coupled femtosecond lasers will enable endoscopic multiphoton microscopy (MPM). We demonstrated two-and three-photon excited fluorescence (2PEF, 3PEF), and second-and third-harmonic generation microscopy (SHG, THG) in human ovarian and fallopian tube tissue. A study was undertaken to understand the mechanisms of contrast in these images. Six patients (normal, cystadenoma, and ovarian adenocarcinoma) provided ovarian and fallopian tube biopsies. The tissue was imaged with three-dimensional optical coherence tomography, multiphoton microscopy, and frozen for histological sectioning. Tissue sections were stained with hematoxylin and eosin, Masson's trichrome, and Sudan black. Approximately 1 mu m resolution images were obtained with an excitation source at 1550 nm. 2PEF signal was absent. SHG signal was mainly from collagen. 3PEF and THG signal came from a variety of sources, including a strong signal from fatty connective tissue and red blood cells. Adenocarcinoma was characterized by loss of SHG signal, whereas cystic abnormalities showed strong SHG. There was limited overlap of two-and three-photon signals, suggesting that three-photon imaging can provide additional information for early diagnosis of ovarian cancer.

A complete two-phase numerical model of film condensation from a mixture of a vapour and a non-condensing gas that is based on the two-dimensional elliptic governing equations with variable physical properties is presented. The model predicts the full viscous flow and heat and mass transfer for the mixture around the tube and in the entire liquid film from the top of the tube to the falling film below the tube. A finite volume method is used with a segregated solution approach and a dynamically moving computational grid that tracks the phase interface sharply. Fundamental balances of mass, energy, and force are enforced accurately at the phase interface. The model was developed in steps and validated against various experimental and theoretical works in the literature for different two-phase flows. The validation tests included stratified flow of liquid and gas in a horizontal channel, falling liquid film over a vertical wall, and condensation of steam from a steam-air mixture in a vertical channel. The model was used to simulate laminar film condensation from a downward flowing steam-air mixture over an isothermal horizontal tube. The validity of this new model is demonstrated by comparisons with previous theoretical and experimental studies. New results are presented on the effects of free-stream-to-tube temperature difference, upstream Reynolds number, free-stream gas mass fraction, and free-stream pressure on the condensate film development, the local and average heat transfer coefficients, and the total condensate mass flow rate. It was found that the temperature difference had the greatest effect on the condensation rate and film thickness. The presence of non-condensing gas in the vapour has a strong negative impact on the condensation process. For the pure steam case, moderate changes in the upstream Reynolds number showed slight increases in condensate mass flow rate with increased Reynolds number. For the mixture case, however, moderate increase in upstream Reynolds number increases significantly the condensate mass flow rate and film thickness. This trend becomes more noticeable as the free-steam gas mass fraction increases. Changing the free-stream pressure demonstrated that property variation had a relatively smaller effect than temperature difference and gas mass fraction changes. / February 2017

La gazéification de la biomasse a été étudiée dans les conditions d'un réacteur à flux entraîné, à savoir à vitesse de chauffage et à température élevées. Des expériences ont été réalisées dans un four à chute entre 800°C et 1400°C, à partir de particules de bois de taille 0,35 mm et 0,80 mm, dans une atmosphère inerte (100% molaire de N2), ou contenant de la vapeur d’eau (25% molaire). Les expériences ont également été simulées grâce à un modèle 1D avec des résultats positifs, ce qui a permis de mieux comprendre les phénomènes mis en jeu. Les solides obtenus (suies et char) ont été analysés et caractérisés. Des rendements élevés en gaz et goudrons, et un faible rendement en char ont été mesurés. Par conséquent, l'évolution de la phase volatile est déterminante pour les rendements des produits finaux. Au-dessus de 1000°C, la formation de suies devient importante. Les suies sont formées à partir de C2H2 et de HAP. En présence de vapeur d’eau, le rendement en suies est nettement moins élevé, ce qui s’explique essentiellement par le vaporeformage des précurseurs de suie, mais aussi par leur gazéification. La réaction de water-gas shift joue un rôle important dans la distribution des gaz majoritaires. La gazéification du char a été mise en évidence à 1200°C et 1400°C sous atmosphère humide. L'ensemble de ces réactions conduit à un gaz riche en H2, CO et CO2. L'équilibre thermodynamique est presque atteint à 1400°C avec une concentration de 25% molaire de H2O dans l’atmosphère. La graphitisation et la désactivation du char porté à haute température ont été mises en évidence expérimentalement. Néanmoins, ces phénomènes ont une influence négligeable sur l’évolution du rendement en char lors des expériences en four à chute. Enfin, la taille des particules n’a presque aucune influence sur les résultats expérimentaux. / Biomass gasification was studied in the conditions of an entrained flow reactor, namely at high heating rate and temperature. Experiments in a drop tube reactor were performed between 800°C and 1400°C, with wood particles of 0.35 mm and 0.80 mm size, under inert and steam containing - 25 mol% of H2O - atmospheres. These experiments were also simulated with a 1D model which gave good predictions. The collected solids, soot and char, were analyzed and characterized. This study highlights the importance of gas phase reactions on the yields of the final products, mainly gaseous compounds, in these conditions. These reactions are hydrocarbons cracking, reforming and polymerization, leading to soot formation, and water-gas shift. Char graphitization and deactivation were experimentally demonstrated. However, these phenomena have a negligible influence on char evolution in the drop tube reactor. Finally, the particle size was shown to have almost no influence on experimental results.

The thesis is focused on nursing care of patient with tracheostomy cannula from the perspective of nurses at the Department of the intensive care or Intensive Care Units. It consists of theoretical and empirical part. Essential terminology, anatomy and physiology of the airways, historical aspects of surgical procedures and types of tracheostomy tubes are described in the theoretical part. Moreover, there are discussed modern surgical techniques, indication and possible complication. The next theoretical chapter is focused on the nursing care. The last chapter deals with the different alternatives of communication of the patient with tracheostomy tubes. The research part uses questionnaires as a quantitative research method. The aim of the thesis is to investigate the theoretical knowledge of the nurses in their care of the patient with tracheotomy tubes and knowledge how to communicate with this patient. The statistically significant results are also listed and discussed. The last part concludes with the recommendations of the best practice in the care of the patient with the tracheostomy tubes. keywords tracheostomy, airway, tracheostomy tube, nursing care

Author's title and name: Bc. Veronika Součková Institute: Charles University, Prague 1. Faculty of medicine Kateřinská 32, 121 08, Prague 2 Study branch: follow-up Master's - intensive care Study programme: specialization in intensive care Title: Nasojejunal tube placement techniques Consultant: MUDr. František Novák, Ph.D. Number of pages: 81 Number of attachments: 3 Number of tables, grafs and pictures: 24 Year of presentation: 2013 Keywords: Nasojejunal tube, placement techniques, enteral nutrition, endoscopy, fluoroscopy, blind bedside technique This dissertation is dedicated to the issue and options in the field of nasojejunal tubes placement technique. Theoretical part aims at the description of methods and procedures of placing the nasojejunal tube and briefly mentions possible complications and principles of enteral nutrition, which is administrated by this method. Empirical part of the dissertation aims at the comparison of placement the nasojejunal tube using the blind bedside technique developed at intensive care unit in General University Hospital in Prague to, endoscopic and fluoroscopic methods. The research brings description and comparison of the most frequently used methods of placement the feeding tube into the small intestine.

Master of Science / Department of Animal Science / R. Scott Beyer / Daniel Y.C. Fung / Clostridium perfringens causes necrotic enteritis (NE), resulting in decreased feed efficiency and increased mortality, costing the poultry industry USD 2 billion a year worldwide. The objective of the first trial was to validate the Fung Double Tube (FDT) to detect and enumerate C. perfringens in chicken intestines. Two methods (FDT and petri plates) and three media (Shahidi Ferguson Perfringens [SFP] with egg supplement, polymyxin B [p], and kanamycin [k; E]; SFP with p and k [P]; and SFP with cycloserine [C]) were arranged in a 2 x 3 factorial, resulting in six treatments. The FDT with medium C (5.35 log CFU/g) had significantly (P<0.05) higher C. perfringens counts than any other media/method combination. The objective of the second and third trials was to determine the effect of diet type on the population of C. perfringens in broiler intestines using the FDT. Trial 2 tested: corn-soybean meal (SBM), low-crude protein (19.8%)/high synthetic amino acids (SAA), and barley (56%)-fishmeal (4%; BF). Diets in Trial 3 included: corn-SBM, barley (7.46%), fishmeal (4%), and BF. Diets in Trial 2 contained an antibiotic and a coccidiostat; diets in Trial 3 did not. After 21 days, birds in Trial 2 fed BF had significantly higher (P<0.05) counts (5.96 log CFU/g) of C. perfringens, as compared to all other diets. Both, corn-SBM and SAA diets resulted in 3.89 log CFU/g. In Trial 3, birds fed the corn-SBM diet (2.7 log CFU/g) had significantly lower (P<0.05) counts than broilers fed BF (4.15 log CFU/g). When broilers were fed fishmeal (3.583 log CFU/g) and barley (3.577 log CFU/g) separately, C. perfringens counts were numerically higher compared to the corn-SBM diet, but numerically lower than birds fed BF. Barley and fishmeal inclusion increased the incidence of C. perfringens, and their combination resulted in a cumulative effect. The FDT method is able to detect C. perfringens at higher levels than the conventional petri plate method (P<0.001) and it also proved to be an effective method to detect differences in C. perfringens counts from the intestines of chickens fed different diet.

Scratch2 (Scrt2) é um fator de transcrição (FT) expresso em células neurais recém-pós-mitóticas. O mecanismo de regulação de sua transcrição permanece desconhecido. Nós buscamos por potenciais elementos cis-regulatórios (CR) e sítios de ligação para FT na região genômica de Scrt2. Nós testamos o efeito in vivo da região CR intrônica através de eletroporação em embrião de galinha. Esta CR intrônica levou à expressão de eGFP tubo neural, mas não gerou um padrão semelhante ao Scrt2 endógeno. Estes dados sugerem que esta região CR pode contribuir com o controle da expressão de Scrt2, mas requer regiões regulatórias adicionais. Nós também verificamos o papel de mAsh1, cPax6, cNgn2 e Brn na regulação da expressão de Scrt2 através da superexpressão destes no tubo neural embrionário. As análises foram realizadas por qPCR e hibridação in situ. A superexpressão de mAsh1 e cNgn2 levou a um leve aumento na expressão de cScrt2 visto através da hibridação in situ. Já a superexpressão de cPax6 e mBrn-Eng reduziu os níveis de cScrt2, com Brn apresentando efeitos mais severos. / Scratch2 (Scrt2) is a transcription factor expressed in early post-mitotic neural cells. The mechanisms that control its transcription remain unknown. We searched for potential cis-regulatory elements and putative transcription factors binding sites in the genomic region of cScrt2. Then, we tested the function of a candidate cis-regulatory intronic region through electroporation in chick embryos. This fragment drove eGFP expression in the neural tube of chick embryo, but its expression did not resemble the cScrt2 endogenous pattern. Thus, this cis-regulatory region likely requires the presence of other regulatory regions. We also evaluated the role of mAsh1, cPax6, cNgn2 e Brn in regulating cScrt2 expression through overexpression of these factors in chick neural tubes and subsequent qPCR and in situ hybridization. Overexpression of mAsh1 and cNgn2 increased slightly cScrt2 expression level as seen by in situ hybridization. Overexpression of cPax6 and mBrn-Eng, reduced cScrt2 levels, with more severe effects with Brn.