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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Utveckling av användarmanual - Aircraft Performance Manual

Nhan, Christine, Andersson, Marcus January 2013 (has links)
Navtech är en internationell leverantör av flygoperationella produkter. Det här examensarbetet utfördes på en av deras produktionsavdelning som kallas Aircraft Performance, i Stockholm. Arbetet består av framtagning av en manual till en mjukvaruprodukt. Produkten är ett program som beräknar och presenterar flygprestandainformation för start och landning. Programmet tillhandahålls med två användarmanualer, Userguide och Prepages. Dessa manualer beskriver hur programmet fungerar och hur det presenterade flygprestandainformation skall användas. Företaget har funnit ett behov av att förbättra innehållet av dessa två manualerna och vill ha hjälp med att skapa en ny, enhetlig och lättanvänd manual. För det har upptäckts att manualerna som tillhandahålls till kunderna inte alltid innehåller all grundläggande information om programmet och lett till att kunderna behöver kontakta Aircraft Performance kundsupport för hjälp och vägledning. Förutom att den nya manualen skulle vara enhetlig ville företaget att innehållet skulle vara generellt och fungera som en grundmall. Detta för att den sedan kunna anpassas efter varje nytt specifikt program. Den nya framtagna manualen har fått namnet Aircraft Performance Manual. För att informationen skall vara konsekvent i hela Aircraft Performance Manual för ett specifikt program har riktlinjer, kallad Developer guidelines, tagits fram under examensarbetet. De beskriver steg för steg vilken information som behöver anpassas för programmet. Denna rapport är en studie av programmets funktionaliteter och manualernas innebörd (Userguide och Prepages) samt Navtechs interna dokumenter som också är relaterad till programmet. Rapporten presenterar resultatet av det första upplägget av Aircraft Performance Manual, som är godkänd av Geneth Daley, Product Manager på Aircraft Performance avdelningen. I och med att Aircraft Performance Manual har blivit ett mycket stort dokument har vissa delar i denna lämnats med förslag till vidare utveckling och bearbetning. Detta är presenterad i slutet av rapporten. / Navtech is an international supplier of flight operational products. This thesis is performed in one of their production department called Aircraft Performance, in Stockholm. The work consists of development of a manual to a software product. The software calculates and presents aircraft performance information for takeoff and landing. The software is provided with two user manuals called Userguide and Prepages. These manuals supply information of how the software works and how to apply the flight performance information. The company has found needs of improving the contents in these manuals and needs help to develop a new and uniform manual that is easy-to-use. It has been discovered that the manuals which have been provided to customers does not always consist of all fundamental information about the software. The consequence of this has led customers to contact Aircraft Performance customer service for help and guidance. In addition to have a uniform manual, the company wants it to be generic and be used as a basic template. The reason is to be able to customize it for every new specific software. The newly developed manual is called Aircraft Performance Manual. To be able to maintain consistent information in the Aircraft Performance Manual for specific software a guideline, called Developer guidelines, has been created during the thesis work. It describes step by step which information needs to be customized for the software. This report consist study of the software functionality, the purpose of the manuals (Userguide and Prepages) and Navtechs internal documentations which also contains information related to the software. The report presents the first edition of the Aircraft Performance Manual, which is approved by Geneth Daley, the Product Manager of Aircraft Performance department. Because Aircraft Performance Manual has become a huge document, some parts have been left out with suggestions for further development och processing. They are presented in the end of this report.
2

Exploitation of the potential of a novel bacterial peroxidase for the development of a new biocatalytic process

Musengi, Amos January 2014 (has links)
Thesis submitted in partial fulfilment of the requirements for the degree Doctor of Technology: Biomedical Technology In the Faculty of Health and Wellness Sciences At the Cape Peninsula University of Technology 2014 / Peroxidases are ubiquitous catalysts that oxidise a wide variety of organic and inorganic compounds employing peroxide as the electron acceptor. They are an important class of oxidative enzymes which are found in nature, where they perform diverse physiological functions. Apart from the white rot fungi, actinomycetes are the only other known source of extracellular peroxidases. In this study, the production of extracellular peroxidase in wild type actinomycete strains was investigated, for the purpose of large-scale production and finding suitable applications. The adjustment of environmental parameters (medium components, pH, temperature and inducers) to optimise extracellular peroxidase production in five different strains was carried out. Five Streptomyces strains isolated from various natural habitats were initially selected for optimisation of their peroxidase production. Streptomyces sp. strain BSII#1 and Streptomyces sp. strain GSIII#1 exhibited the highest peroxidase activities (1.30±0.04 U ml-1 and 0.757±0.01 U ml-1, respectively) in a complex production medium at 37°C and pH 8.0 in both cases. Maximum enzyme production for Streptomyces strain BSII#1 was obtained in the presence of 0.1 mM veratryl alcohol or pyrogallol, while 0.1 mM guaiacol induced the highest peroxidase production in Streptomyces sp. strain GSIII#1. As the highest peroxidase producer, Streptomyces sp. strain BSII#1 was selected for further studies. The strain was first characterised by a polyphasic approach, and was shown to belong to the genus Streptomyces using various chemotaxonomic, genotypic and phenotypic tests. Production of peroxidase was scaled up to larger volumes in different bioreactor formats. The airlift configuration was optimal for peroxidase production, with Streptomyces sp. strain BSII#1 achieving maximum production (4.76±0.46 U ml-1) in the 3 l culture volume within 60 hrs of incubation. A protocol for the purification of the peroxidase was developed, which involved sequential steps of acid and acetone precipitation, as well as ultrafiltration. A purification factor of at least 46-fold was achieved using this method and the protein was further analysed by LC-MS. The protein was shown to be a 46 kDa protein, and further biochemical characterisation showed that the peroxidase had a narrower spectrum of substrates as compared to reports on other peroxidases derived from actinomycetes. With 2,4-dichlorophenol as the substrate, the Km and Vmax for this enzyme were 0.893 mM and 1.081 μmol min-1, respectively. The purified peroxidase was also capable of catalysing coupling reactions between several phenolic monomer pairs. Overall, the peroxidase from Streptomyces sp. strain BSII#1 could feasibly be produced in larger scales and there remains further room to investigate other potential applications for this enzyme.
3

Application of multivariate regression techniques to paint: for the quantitive FTIR spectroscopic analysis of polymeric components

Phala, Adeela Colyne January 2011 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology Chemistry in the Faculty of (Science) Supervisor: Professor T.N. van der Walt Bellville campus Date submitted: October 2011 / It is important to quantify polymeric components in a coating because they greatly influence the performance of a coating. The difficulty associated with analysis of polymers by Fourier transform infrared (FTIR) analysis’s is that colinearities arise from similar or overlapping spectral features. A quantitative FTIR method with attenuated total reflectance coupled to multivariate/ chemometric analysis is presented. It allows for simultaneous quantification of 3 polymeric components; a rheology modifier, organic opacifier and styrene acrylic binder, with no prior extraction or separation from the paint. The factor based methods partial least squares (PLS) and principle component regression (PCR) permit colinearities by decomposing the spectral data into smaller matrices with principle scores and loading vectors. For model building spectral information from calibrators and validation samples at different analysis regions were incorporated. PCR and PLS were used to inspect the variation within the sample set. The PLS algorithms were found to predict the polymeric components the best. The concentrations of the polymeric components in a coating were predicted with the calibration model. Three PLS models each with different analysis regions yielded a coefficient of correlation R2 close to 1 for each of the components. The root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) was less than 5%. The best out-put was obtained where spectral features of water was included (Trial 3). The prediction residual values for the three models ranged from 2 to -2 and 10 to -10. The method allows paint samples to be analysed in pure form and opens many opportunities for other coating components to be analysed in the same way.
4

In vitro propagation of Agathosma betulina an indigenous plant of economic importance

Witbooi, Hildegard January 2013 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Horticultural Sciences in the Faculty of Applied Sciences at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY Supervisor: Dr L Kambizi Co-supervisor: Dr NP Makunga Cape Town December 2013 / Agathosma betulina (Berg.) Pillans, previously known as Barosma betulina, is a member of the Rutaceae family, and indigenous to the fynbos botanical biome of the Western Cape of South Africa. It is commonly known as buchu. Extracts as well as powdered leaves have traditionally been used for the treatment of various ailments. The increase in the international demand for A. betulina for health as well as food and beverage benefits, have raised concerns over exploitation of wild populations and the lack of horticultural information necessitates this study to evaluate the propagation of this economical important species. The main objective of this study was to establish a simple and highly productive micropropagation protocol for A. betulina through experimenting with nodal explants. Testing of the effect of various treatments (physical scarification, chemical scarification, GA, stratification, smoke and combinations thereof) on the in vitro germination of A. betulina seeds was done to elucidate the factors which control seed germination. The study revealed that the physical scarification and smoke-induced germination had a significant effect on germination percentages. In terms of germination rate, the radical generally started to appear after approximately 10 days in the physical scarification with smoke treatment. Initial decontamination methods with the exposure of various concentrations of NaOCl gave fatal results, however 1.5% NaOCl had more phenolic reactions rather than fungal or bacterial contamination. Interestingly, contamination rates of explants were influenced by the stage of maturity of the explant material. This plant material was used to test different strengths of regeneration media, to ensure that the explants receive ample nutrients. Results made exhibited that ½ MS was the best strength for growing A. betulina nodal explants. Compared comparison between in vitro derived explants and ex vitro collected explants showed that the ex vitro derived explants had significant results, but the explants lost vigour soon after the initial exponential growth leading to the explants dying off. Furthermore, ex vitro decontaminated plant material was not economically viable to continue with. Seedlings derived from germinated seeds appeared to be the preferred method of propagation as this spent the least time in culture and produced a stable plant with an established root system, which is essential during the hardening off process after in vitro growth. When exposing nodal explants to phytohormone 2,4-D it responds best to dosages 0.5mg Lˉ¹ and 1mg Lˉ¹. Phytohormone BA was very effective in producing soft friable callus. The best results were shown when 0.5mg Lˉ¹ BA was applied to ½ MS media. For both shoot length and multiple shoot production, a combination of phytohormones BA-NAA (1: 0.5mgLˉ¹) had the most significant results. Interestingly, a higher phytohormone concentration of NAA is necessary to develop multiple adventitious roots. The effect of 3mg Lˉ¹ was significant in that it resulted in multiple adventitious roots, but fewer calli was observed in this treatment. Micropropagation becomes valuable as little attention between subcultures is needed; making it less labour intensive compared to conventional nursery propagation systems where weeding watering and spraying of plants are labour intensive. In the traditional world of medicine, more so in Southern Africa, extracts are prepared by adding boiling water to the plant material; however commercial ethanol is used as an extractant. Establishment of the essential oil quality of the in vitro cultures post exposure to various treatments was done. Analysis of essential oils from A. betulina resulted in the identification of twenty one compounds. The results showed qualitative as well as quantitative differences amongst the samples used in the study. The highest relative concentration of limonene was observed in the callus of nodal explants after it was exposed to 0.5mg lˉ¹ NAA. No pulegone was found in this treatment making it ideal for limonene production. This suggests that liquid culture with the same treatment may produce more calli making it ideal for the production of limonene.
5

Performance of a symmetrical converging-diverging tube differential pressure flow meter

Ilunga, Luc Mwamba January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Civil Engineering in the Faculty of Engineering at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2014 / The current problems of orifice, nozzle and Venturi flow meters are that they are limited to turbulent flow and the permanent pressure drop produced in the pipeline. To improve these inadequacies, converging-diverging (C-D) tubes were manufactured, consisting of symmetrical converging and diverging cones, where the throat is the annular section between the two cones, with various angles and diameter ratios to improve the permanent pressure loss and flow measurement range. The objective of this study was firstly to evaluate the permanent pressure loss, secondly to determine the discharge coefficient values for various C-D tubes and compare them with the existing differential pressure flow meter using Newtonian and non-Newtonian fluids, and finally to assess the performance of these differential pressure flow meters. The tests were conducted on the multipurpose test rig in the slurry laboratory at the Cape Peninsula University of Technology. Newtonian and non-Newtonian fluids were used to conduct experiments in five different C-D tube flow meters with diameter ratios (β) of 0.5, 0.6 and 0.7, and with angles of the wall to the axis of the tube (θ) of 15°, 30° and 45°. The results for each test are presented firstly in the form of static pressure at different flow rates. It was observed that the permanent pressure loss decreases with the flow rate and the length of the C-D tube. Secondly, the results are presented in terms of discharge coefficient versus Reynolds number. It was found that the Cd values at 15° drop earlier than at 30° and 45°; when viscous forces become predominant, the Cd increases with increasing beta ratio. The Cd was found to be independent of the Reynolds number for Re>2000 and also a function of angle and beta ratio. Preamble Performance of a symmetrical converging-diverging tube differential pressure flow meter Finally, the error analyses of discharge coefficients were assessed to determine the performance criteria. The standard variation was found to increase when the Reynolds number decreases. The average discharge coefficient values and their uncertainties were determined to select the most promising C-D tube geometry. An average Cd of 0.96, with an uncertainty of ±0.5 % for a range of Reynolds numbers greater than 2,000 was found. The comparison between C-D tubes 0.6(15-15) and classical Venturi flow meters reveals that C-D 0.6(15-15) performs well in turbulent range and shows only a slight inaccuracy in laminar. This thesis provides a simple geometrical differential pressure flow meter with a constant Cd value over a Reynolds number range of 2000 to 150 000.
6

A performance study of a voltage-fed reluctance synchronous machine

Smith, Robert Albert January 2013 (has links)
Submitted to the Department of Electrical Engineering in Fulfilment of the Requirements for the Magister Technologiae in Electrical Engineering at the Cape Peninsula University of Technology SUPERVISOR: E. VOSS NOVEMBER 2013 / The reluctance synchronous machine (RSM) operates on the principle of magnetic reluctance, which is produced through a careful selection of rotor flux barriers and cut-outs. Magnetic reluctivity is the resistance to magnetic flux and can be directly related to the principles of Ohm’s law in electrical circuits. Although reluctance motors have been known for more than 150 years, researchers lost interest when Nikola Tesla’s induction machine (IM) was introduced to industry. Over the last few decades, however, RSMs have shown a lot of potential. They are cheap, robust, reliable, and their rotors can also be used in the stators of IMs. The disadvantage of these machines is an inherently high torque ripple, being the result of its rotor geometry, but the biggest advantage is having a significant reduction in copper losses after the rotor cage has been removed. This advantage drove engineers to investigate, optimise and modify the performance and structure of this machine, which led to the usage of electronic drive systems. The recent advances in technology have allowed researchers to further investigate and modify the design and performance of this special type of machine, with the integration of Finite Element Analysis (FEA) software also making a contribution to the development of the RSM’s current driven systems. The voltage-fed RSM, driven direct-on-line (DOL) from the utility supply, was left in the shadows as the current-fed RSM took reign, but still is, in the author’s opinion, not yet fully analysed. This thesis practically investigates the performance characteristics of the cageless, voltage-fed 3kW RSM in its steady-state operation, under various loads. These performance characteristics are also compared to a RSM driven from a sensorless vector drive (current-fed) to investigate the advantages and disadvantages between the two. Experiments performed on the test bench immediately reveal a limitation to the voltage-fed RSM’s ability to drive higher loads. While the current-fed RSM conveniently reaches 150% of its full-load, the voltage-fed RSM, due to its cageless structure, only reaches 110% of its full-load power. Despite this discovery, the voltage-fed RSM proves to have a lower core loss, harmonic content and torque ripple. Using a FE software package with an integrated source-code, additional parameters such as the dq-axis inductances and currents are also compared and analysed in terms of its reaction to an increase in load. The eddy-current, hysteresis and excess losses are also analysed as well as the harmonic components caused by the geometry of the RSM. For academic purposes, a fair amount of emphasis is placed on the approach to the problem. The preparation for the FE simulation is explained in detail, providing insight into the FE mathematical model as well as parameter acquisition. These parameters include current angle, friction and windage losses, stator resistance, end-winding leakage reactance, core loss and inertia. The results obtained by the FE model are compared to that of the measured results and is found to have an error of only 0.52%. Furthermore, this study attempts to find the feasibility of the voltage-fed RSM’s practicality in modern-day industry. The conclusion is drawn that the voltage-fed RSM could be used as a more elegant alternative to an otherwise over-complicated and over-priced installation.
7

A practical investigation into the measurement of forces on the stator teeth of electrical machines

Bevan, Graeme Rhys January 2013 (has links)
Submitted to the Department of Electrical Engineering in Fulfilment of the Requirements for the Magister Technologiae in Electrical Engineering at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY SUPERVISOR: E. VOSS NOVEMBER 2013 / Radial and peripheral displacement of stator teeth in electrical machines is known to be the cause of undesired vibration which leads to noise. This thesis serves to investigate the possibility of physically measuring the radial displacement of stator teeth caused by electromagnetic forces which, to the author’s knowledge, has not yet been achieved. A simplified practical approach is adopted in order to address the inherent difficulties attached to this problem, and the measurement of displacement is done by means of an experimental rig where a tooth is subjected to magnetic force acting over an air gap. Three experiments are carried out, each comprising ten tests, the results of which are compared in order to gain some idea as to the magnitudes of displacement which can be expected over a range of applied air gap flux densities. The aim of this work is to observe the displacement response of magnetised EM core material when acted upon by forces, and to see if the measured results agree with the elastic displacement predicted by a wellknown formula. It will be shown that although the measured results are in the same range as the predicted results, there is a deviation from the predicted linearity due to certain characteristics of the force rig, which are explained. The chosen measurement method is capacitive displacement and is shown to be a viable alternative to the more commonly used search coils and vibrometers in past literatures, especially when measuring displacements on the nano-scale. In addition, this study shows the importance of using 3D finite element software to simulate the electromagnetic model when saturation is present in the core of the test specimen. The important findings of this work are discussed in detail, and some ideas put forward, in an attempt to establish a starting point for future related work in the measurement of electromagnetic forceinduced displacement of stator teeth in electrical machines.
8

Solvent dependent growth of one-dimensional crystalline ß-FeOOH nanorods

Chowdhury, Mahabubur Rahman January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree DOCTOR TECHNOLOGIAE: ENGINEERING: CHEMICAL in the FACULTY OF ENGINEERING at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2014 / Several authors have reported on the use of alcohols – water /or mixed solvents to synthesise metal oxide nanoparticles. However, no systematic study has been carried out to evaluate the effect of mixed solvent on the particle characteristics, although considerable research has been reported, a gap still exists with regard to the effect of the alcohols as solvents on the growth kinetics of nanoparticles. To address these issues, four different alcohols, namely, methanol (MeOH), ethanol (EtOH), propanol (PrOH) and butanol (BuOH) were used as solvents in the synthesis of β-FeOOH particles. The effect of organic solvents on the growth kinetics of β-FeOOH nanorods has been evaluated for the first time in this study. Two-stage growth of akaganeite nanorods has been observed in BuOH and PrOH. The first growth stage follows a typical power law representing Ostwald ripening (OR) kinetic. The second stage was found to be asymptotic and obeyed oriented attachment (OA) kinetic. The proof of the OA kinetic also comes from the HRTEM images of the synthesised particles. Simultaneous occurrence of the two mechanisms was observed in the growth of the particles synthesised in EtOH and MeOH. The rate constants for OR kinetic, KOR, was found to be higher than the rate constant for OA kinetic, KOA, for different solvents used. Preamble The use of a mixed solvent is a new approach in the synthesis and processing of materials. Various researchers have stated that the surface tension of the solvent plays an important role in the formation of uniform nanorods. However, the effect of surface tension was not correlated with the particle growth, earlier, though the dielectric properties of the mixed solvents were only taken into account. Additionally, no quantitative or qualitative relationship was presented between surface tension and particle growth in the literature. In this work an attempt to correlate these two parameters (surface tension and particle growth) with the concentration of the precursor and temperature was made, resulting in an exponential relationship between KOR for the particle growth and surface tension of the alcohols. Furthermore, the relationship between surface tension and particle growth was validated by an independent study using statistically designed experiments to account for the influence of various process variables on the particle growth. The findings in this study obtained from both theoretical and experimental work provides an insight into the relationship between solvent surface tension and particle growth interactions, producing a new piece of information that will further promote our understanding of the formation mechanisms of β- FeOOH growth. The transformation temperature of akaganeite (β-FeOOH) nanorods to hematite (α-Fe2O3) particles was found to be solvent dependent. Thermogravimetric analysis and differential scanning calorimetry were performed to evaluate the effect of alcohol on the thermodynamic stability of the particles. Alcohol as solvent played a significant role in the dehydration property of the synthesised particles. The percentage mass loss of the particles at 300°C decreases linearly with increasing carbon number in the linear alkyl chain of the solvent. The effect of alcohol type on the particle morphology was found to be more pronounced at higher FeCl3 concentrations (>0.5M). Splitting of β-FeOOH nanorods was observed at FeCl3 concentration of 0.7M in BuOH. In PrOH, rectangular morphologies were obtained whereas nanoribbons resulted in surfactant-free conditions. It was found that the nature of anions (chloride vs. nitrate and sulphate) in the precursor salt also influenced the morphology.
9

The design, numerical modelling and development of MEMS fabrication process of micro bolometer for use in long wave infrared detection.

Senda, Paul Tudieji January 2013 (has links)
Master of Technology: Mechanical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology Supervisor:Prof Philander Oscar Bellville Campus Date of submission: April 2013 / The Advanced Manufacturing Technology Strategy (AMTS), predecessor of the Technology Innovation Agency, was a national strategy focused principally on improving collaboration amongst industry, academia and science councils. The aerospace industries and training institutions in particular have been identified as key thrust areas for achieving economic development through the AMTS. Furthermore, the AMTS Aerospace Interest Group has been identified as one of the most important facets of Micro and Nano Manufacturing, Sensors and Electronics Flagship Program. The manufacturing of Micro and Nano Electronics and sensors is essential for South Africa to sustain the technology capability development as seen in developed countries. For example, there is an urgent need to establish a Photo Lithography facility for South African industry and training Institutions. The demand for the new generations of industrial, military, commercial, medical, automotive and aerospace products in South Africa in particular, and in the world in general, has fuelled research and development activities focused on advanced and smart materials. This situation has allowed for the emergence of a new generation of infrared sensors, the bolometer, based on an infrared thermal detection mechanism which is particularly suited to operate at ambient temperature, opening opportunities for achieving low cost infrared imaging systems for both military and commercial applications. This work deals with different South African bolometer membranes of the second prototype in collaboration with the University of Pretoria and Denel Optronics. The bolometer is an infrared thermal sensor that measures thermal radiation by converting said radiation into a temperature change and subsequently measuring the induced change in electrical resistance. The term infrared from Latin Infra, meaning below, is usually applied to wavelengths between 700nm and 1mm. It can be argued that the first occurrence of infrared sensing actually goes back several millennia, when men placed their hands over recently extinguished fire. However, until Herschel’s experiment, this kind of infrared was between the sun and the earth. Thermal imaging, which refers to the ability to measure the temperature of different points on a scene, requires either an array of infrared detectors operating in those wavelength ranges or a way to scan a scene using a single detector. To realise this work, objectives have been assigned to different groups of the consortium represented by CPUT, UP and Denel. Analyses of thirteen bolometer membranes including metal bolometer (Titanium) and Vanadium oxide were assigned to CPUT, reason why this thesis focuses on the modelling, designing and testing of the bolometer membranes. Masks design of the second prototype bolometer test structures includes several thermally isolated bolometer devices. These devices have been modelled and analysed in order to study their electrical and thermal behaviour. / Cape Peninsula University of Technology University of Pretoria Denel Optronics
10

Effects of dietary Garcinia kola supplementation and oxidative stress in isolated perfused rat hearts

Nyepetsi, Naledi Gape January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree of Master of Technology: Biomedical Technology In the Faculty of Health and Wellness Sciences At the Cape Peninsula University of Technology Supervisors: Prof. Adriaan J Esterhuyse Dr Dirk J Bester Bellville January 2014 / Background: Oxidative stress and chronic inflammation contributes significantly to the pathogenesis of several ischaemic heart diseases, including atherosclerotic plaque rupture and myocardial infarction. It is widely demonstrated that ischaemia, followed by reperfusion, results in alterations of the mitochondrial and endothelial function through uncontrolled cascades of events characterized by free radical release and inflammation. Recent experimental evidence shows that modulation of inflammatory and antioxidant signaling mediators may determine the host outcome following myocardial ischaemia-reperfusion injury. Investigations from the past decade indicate that food supplements may play an important role in the prevention and management of chronic inflammatory diseases. Garcinia kola seeds are flavonoid rich nut from a tropical flowering, non-timber plant of the Guttiferae family. This plant is highly valued in several African cultures for its use in herbal medicine. Recently, the majority of experimental research has linked phytochemicals found in Garcinia kola nut, to its proposed beneficial effects in treatment and management of oxidative stress related-chronic diseases. Research performed in our laboratory demonstrated that kolaviron, a prominent Garcinia kola flavonoid extract, reduces myocardial apoptosis during ischaemia-reperfusion injury. Therefore, the aim of our current study was to determine the effects of Garcinia kola supplementation on cardiac inflammatory and antioxidant signaling pathways during ischaemia-reperfusion using a Wistar rat heart model. Materials and Methods: Male wistar rats were randomly divided into two groups: a control group receiving 2ml/kg corn oil and the experimental group receiving 100mg/kg Garcinia kola dissolved in corn oil, daily for 4 weeks. After the feeding period, blood samples were collected and lymphocytic DNA damage was analyzed using the alkaline comet assay. Furthermore, rat hearts were isolated and perfused with Krebs-Henseleit buffer on a working heart perfusion apparatus to measure myocardial functional parameters. Myocardial functional recovery was measured after 15 minutes global ischaemia followed by 25 minutes reperfusion. Hearts were freeze clamped at three different time points for myocardial cytokine concentration determinations using multiplex electrochemilunescent immunoassay. Nuclear factor kappa beta (NF- kβ), p38 mitogen activated protein kinases (p38 MAPK), protein kinase B/Akt (PKB/Akt), nitro-tyrosine, inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2), poly (adenosine-di-phosphate) ribose polymerase-1 (PARP-1) and caspase-3 expression and their phosphorylated forms (where applicable) were analyzed using the Western blot technique. Results: Dietary Garcinia kola supplementation significantly improved functional recovery when compared to the control group as reflected by the improved aortic output recovery (68.47 ± 6.16% versus 44.96 ± 7.00%; p<0.05). Our biochemical results supports the hypothesis that, dietary Garcinia kola supplementation modulates different cardiac proteins in terms of expression and activation at different time points when compared to the control group. We show that, before induction of ischaemia, Garcinia kola supplementation attenuates expression of inflammatory mediators and pro-apoptotic proteins when compared to the control group. The improved functional recovery was associated with a prompt inflammatory response, activation of PKB/Akt and attenuation of protein nitrosylation after 10 minutes of reperfusion. Modulation of NF-kβ and the p38 MAPK family proteins expression could have also played a significant role in myocardial functional recovery. Conclusion: We have shown that a 4 week period of dietary Garcinia kola supplementation at 100mg/kg daily improves cardiac functional recovery following ischaemia-reperfusion injury. We propose that dietary Garcinia kola supplementation protects cardiac myocytes from ischaemia-reperfusion induced oxidative stress through the induction of a prompt inflammatory response and controlled expression and/or activation of the, NF-kβ, PKB/Akt and p38 MAPK protein signaling pathways PARP-1 and caspase. Finally, we demonstrated that dietary Garcinia kola supplementation did not induce rat lymphocytic DNA damage when compared to the control group.

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