The iron ore mining industry makes use of various processes that result in the release of airborne dust into the surrounding atmosphere where workers are exposed, to produce a final product. The deposition in the lung and toxicological influences of airborne dust can be determined by their physical- and chemical characteristics. The Occupational Health and Safety Act (OHSA) regulations for hazardous chemical substances have no current system of how the physical- and chemical properties of particulates originating from specific areas will influence a worker‘s exposure and health, especially for ultrafine particles (UFP). It is therefore imperative to characterise airborne dust containing micrometer and UFP size particles originating from specific areas to determine if there are physical- and chemical characteristics that may or may not have an influence on the workers‘ health. Aim: This pilot study is aimed at the physical- and chemical characterisation of the airborne iron ore dust generated at the process areas of an opencast iron ore mine. Method: Sampled areas included the Primary-secondary crusher, Tertiary crusher, Quaternary crusher and Sifting house. Gravimetric sampling was conducted through the use of static inhalable- and respirable samplers in conjunction with optical- and condensation particle counters that were placed near airborne dust- emitting sources. Physical- and chemical characterisation was done with the use of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results: The results found in the study indicate high mass concentration levels of inhalable dust at all four process areas, as well as high levels of respirable dust found at the primary- secondary crusher area. Particle size distribution optical particle counter (OPC) results indicate that the majority of particles at all four process areas are in the region of 0.3 μm in size. Condensation particle counter (CPC) results integrated with OPC results indicate that at the primarysecondary and Tertiary crushers the majority of particles are found to be in the size fraction <0.3 μm. SEM analysis indicates that particle agglomeration largely occurs in the airborne iron ore dust. Particle splinters originating from larger particle collisions and breakages are present in the airborne dust. EDS analysis indicates that the elemental majority of the airborne iron ore dust consists of iron, oxygen, carbon, aluminium, silicon, potassium and calcium. The elemental percentages differ from each process area where an increase in iron and decrease in impurities can be seen as the ore moves through the beneficiation process from the Primary-secondary crusher to the Sifting house. Conclusion: The results obtained from the physical- and chemical properties of the airborne iron ore dust indicate high risk of over-exposure to the respiratory system, as well as possible ultrafine particle systemic exposure, that may overwhelm the physiological defense mechanisms of the human body and lead to reactive oxygen species (ROS) formation and the development of pathologies such as siderosis, silicasiderosis and lung cancer. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

The perception is that inborn errors of metabolism (IEM) are rare, but the reality is that more than 600 lEMs are now recognized. The organic aciduria, 3-methylcrotonyl-CoA carboxylase (MCC) deficiency arises when 3-methylcrotonyl-Coenzyme A (CoA) carboxylase that participates in the fourth step of the leucine catabolism is defective. Tandem mass spectrometry (MS/MS) based screening programmes in North America, Europe and Australia, showed that MCC deficiency is the most frequent organic aciduria detected, with an average frequency of 1:50 000. Therefore MCC deficiency is considered an emerging disease in these regions. The incidence of MCC deficiency in the Republic of South Africa (RSA) is not yet known. However, one 48 year old male Caucasian individual (HGS) was diagnosed suffering from mild MCC deficiency, since elevated levels of 3-hydroxyisovaleric acid, 3- hydroxyisovalerylcarnitine, 3-methylcrotonylglycine was present in his urine. Several groups are currently working on various aspects of this emerging disease with the focus on the molecular characterisation of MCC deficiency. In the RSA no molecular based diagnostic method which complements MS/MS screening programmes have yet been implemented. Therefore, the aim of this study was to implement the necessary techniques for the molecular characterisation of MCC deficiency, the determination of the sequence of the open reading frame (ORF) of mccA and mccB subunits to determine which mutation(s) are present in the South African MCC deficient patient. For the implementation of the molecular characterisation, a two-pronged approached was used to characterize MCC of a MCC non-deficient individual (CFC). This approach included the reverse transcriptase polymerase chain reaction (RT-PCR) amplification of the ORFs of the associated genes [mccA (19 exons) and mccB (17 exons] and the PCR amplification of selected (genomic deoxyribonucleic acid (gDNA) regions (exons mccA8, mccA11 , mccB5, mccB6 and mccB5-intron 5-6 exon 6 (mccB5-6) which have been found to have mutations associated with MCC deficiency in Caucasians. The sequence analyses produced surprising results of the amplified ORFs (CFCmccA and CFCmccB) of the MCC non-deficient individual CFC. A non-synonymous single nucleotide polymorphism (SNP) (1391C→A, H464P) associated with MCC deficiency (Gallardo et al., 2001) was identified in the CFCmccA subunit. Another SNP (1368G→A, A456A) recently listed in GenBank was observed in the amplified CFCmccB ORF. No significant novel variations or described mutations were identified in the amplified genomic regions mccA8, mccA11 ,mccB5, mccB6 and mccB5-6. The implemented molecular approach was used to characterise MCC of our MCC deficient patient (HGS). The patient did not have any mutation in the four selected exons mccA8, mccA11, mccB5, mccB6 or the genomic region mccB5-6. The RT-PCR amplification of both ORFs (HGSmccA and HGSmccB) resulted in multiple amplicons. Gel extracted amplicons of the expected size were sequenced. Of the 36 exons, 34 exons were sequenced. This includes all 19 exons of HGSmccA and 15 of 17 exons of HGSmccB (exons 1-6 and exons 9-17). The non-synonymous SNP (1391C→A, H464P) detected in CFCmccA (MCC non-deficient individual), seems to be present in the HGSmccA subunit of the MCC deficient individual, HGS. The HGSmccB amplicons could not be entirely sequenced. However, the region exon 1-6 and 9-17 was sequenced but no described or novel mutations were identified. The lack of sequence data of region exon 7-8 led to an incomplete molecular characterisation of the MCC deficiency in HGS. In conclusion, the basic methods and techniques for the molecular characterisation of MCC deficient patients have been implemented locally. A few additional sequencing primers need to be designed to cover mccB7 and mccB8 as well as the entire coding and non-coding strands of each MCC gene (mccA and mccB). The primers for RT-PCR of both mccA and mccB need to be further refined to ensure better specificity. / Thesis (M.Sc. (Biochemistry))--North-West University, Potchefstroom Campus, 2007.

Adhesive bonding is one of the most attractive joining techniques for any structural application, including high profile examples in the aerospace, automotive, marine construction and electrical industries. Advantages of adhesive bonding include; superior fatigue performance, better stress distribution and higher stiffness than conventional joining techniques. When the design of bonded joints is considered, fatigue is of critical importance in most structural applications. There are two main issues that are of importance; a) in-service damage characterisation during fatigue loading and, b) lifetime prediction under both constant and variable amplitude fatigue loading. If fatigue damage characterisation is considered, there has been some work to characterise damage in-situ using the backface strain (BFS) measurement technique, however, there has been little investigation of the effects of different types of fatigue behaviour under different types of geometry and loading. Regarding fatigue lifetime prediction of bonded joints, most of the work in the literature is concentrated with constant amplitude fatigue, rather than variable amplitude fatigue. Fatigue design of a bonded structure based on constant amplitude fatigue, when the actual loading on the structure is of the variable amplitude fatigue, can result in erroneous lifetime prediction. This is because of load interaction effects caused by changes in load ratio, mean load etc., which can decrease the fatigue life considerably. Therefore, the project aims to a) provide a comprehensive study of the use of BFS measurements to characterise fatigue damage, b) develop novel techniques for predicting lifetime under constant amplitude fatigue and c) provide an insight into various types of load interaction effects. In this project, single lap joints (SLJ) and compound double cantilever beam geometries were used. Compound double cantilever beams were used mainly to determine the critical strain energy release rate and to obtain the relationship between strain energy release rate and fatigue crack growth rate. The fatigue life of SLJs was found to be dominated by crack initiation at lower fatigue loads. At higher fatigue loads, fatigue life was found to consist of three phases; initiation, stable crack propagation and fast crack growth. Using these results, a novel damage progression model was developed, which can be used to predict the remaining life of a bonded structure. A non-linear strength wearout model (NLSWM) was also proposed, based on strength wearout experiments, where a normalised strength wearout curve was found to be independent of the fatigue load applied. In this model, an empirical parameter determined from a small number of experiments, can be used to determine the residual strength and remaining life of a bonded structure. A fracture mechanics approach based on the Paris law was also used to predict the fatigue lifetime under constant amplitude fatigue. This latter method was found to under-predict the fatigue life, especially at lower fatigue loads, which was attributed to the absence of a crack initiation phase in the fracture mechanics based approach. A damage mechanics based approach, in which a damage evolution law was proposed based on plastic strain, was found to predict the fatigue life well at both lower and higher fatigue loads. This model was able to predict both initiation and propagation phases. Based on the same model, a unified fatigue methodology (UFM) was proposed, which can be used to not only predict the fatigue lifetime, but also various other fatigue parameters such as BFS, strength wearout and stiffness wearout. The final part of the project investigated variable amplitude fatigue. In this case, fatigue lifetime was found to decrease, owing to damage and crack growth acceleration in various types of variable amplitude fatigue loading spectra. A number of different strength wearout approaches were proposed to predict fatigue lifetime under variable amplitude fatigue loading. The NLSWM, where no interaction effects were considered was found to over-predict the fatigue life, especially at lower fatigue loads. However, approaches such as the modified cycle mix and normalised cycle mix approaches were found to predict the fatigue life well at all loads and for all types of variable amplitude fatigue spectra. Progressive damage models were also applied to predict fatigue lifetime under variable amplitude fatigue loading. In this case a fracture mechanics based approach was found to under-predict the fatigue life for all types of spectra at lower loads, which was established to the absence of a crack initiation phase in this method. Whereas, a damage mechanics based approach was found to over-predict the fatigue lifetime for all the types of variable amplitude fatigue spectra, however the over- prediction remained mostly within the scatter of the experimental fatigue life data. It was concluded that, the damage mechanics based approach has potential for further modification and should be tested on different types of geometry and spectra.

In 2006 a new training route for Educational Psychologists (EPs) was introduced, which extended the entry criteria to applicants from a range of professional backgrounds. The related literature indicates that this was a contentious issue. The aim of the current study is to explore the relationship between the role of the EP and professional background using an interpretive methodology. Twelve participants were interviewed using a semi-structured interview format. The participants were four EPs, four primary Special Educational Needs Co-ordinators (SENCos), three secondary SENCos and a Portage Worker. The aim of the study is also to establish what skills and qualities the participants perceive to be necessary to be an effective and credible practitioner. Following analysis of the interview data, a number of themes emerged. In terms of desirable EP attributes, the participants’ responses fell into three broad categories, interpersonal skills, psychological skills and other qualities. The participants perceived the EP role as either expert or collaborative, although some expressed a degree of uncertainty about the nature of the role. All of the participants alluded to a link between experience and credibility, although the nature of desirable experience varied between personal and professional experience. Participants who viewed the role of the EP within an expert model favoured teaching experience over other forms of pre-training experience. The second stage of this study is set in the context of the recent changes to the initial training of Educational Psychologists (EPs). The broad aim of the study is to explore beliefs that are held in relation to the relationship between the role of the EP and professional background. In particular, stage two aims to explore the participants’ belief systems in greater depth. It was therefore deemed that Personal Construct Psychology (PCP) would provide an appropriate psychological framework to inform the design of the study and interpretation of the data. Six of the twelve participants who were interviewed at stage one of this study participated in follow-up interviews using a self-characterisation technique. Their responses were laddered in order to elicit superordinate constructs, until an end point was agreed upon between participant and researcher, which are referred to as ‘core constructs’. The data were clustered in relation to the themes arising from stage one, resulting in six clusters, collaboration, motivation and applying psychology being ranked as most important for EPs. The use of PCP as a theoretical framework has provided a psychological perspective from which to address beliefs regarding the professional background of EPs.

Landscape is about the relationship between people and place and in 2000 was defined by the European Landscape Commission (ELC) as "an area as perceived by people whose character is the result of natural and human actions and interactions”. In the 70s the reason for studying the landscape was because of the necessity of attributing a value to it. Nowadays the motivations behind managing, conserving and enhancing the landscape is because the landscape is the place where people belong to and, consciously or not, recognise themselves. In addition, people identify different landscapes on the basis of the particular combinations of the elements in the landscape. As a consequence a landscape can be distinguished from another on the basis of its character which, according to the Landscape Character Assessment (LCA) guidance for England and Scotland (C. Swanwick and Land Use Consultant, 2002), is defined as “a distinct, recognisable and consistent pattern of elements in the landscape that makes one landscape different from the other rather than better or worse”. This definition was the starting point of a PhD research project aimed at developing and implementing a methodology able to identify and quantify the character of the Scottish landscape through the application of GIS and statistics. The reason for doing this research was to provide the landscape architects and practitioners with a tool that could help them to define the landscape character types in a more consistent, objective, and scientifically robust way. One of the objectives of the research was to identify the spatial patterns formed by the landscape elements by taking into account the influence of the spatial location. The first law of geography, which states that "everything is related to everything else but near things are more related than distant ones" (W Tobler, 1970), was transposed in the assumption of the presence of spatial autocorrelation amongst the data which contributes to form spatial patterns within the data. Since landscape comprises of many elements, data were also multivariate, thus the analysis required a method of calculation able to deal simultaneously with multivariate and spatial autocorrelation issues. MULTISPATI-PCA, a spatially constrained Principal Component Analysis, was the statistical technique applied for the analysis of the data whose results showed that it was possible to detect the spatial structure of the data and that each spatial pattern corresponded to a distinct landscape. Despite their importance in forming the character of the landscape, aesthetic and perceptual aspects were not inlcuded in MULTISPATI-PCA analysis. It was preferred to test the technique only on data that were quantifiable in a more objective way. Perhaps taking into account the human perception of the landscape can be the starting point for future investigation.

Ruminococcus gnavus E1 appartient au groupe des Firmicutes, l’un des deux groupes dominants du microbiote intestinal humain. Les a-galactosidases sont des glycosides hydrolase (GH) actives sur des substrats contenant des galactoses liés en a. Elles sont très largement distribuées dans tous les domaines du vivant, bactéries, champignons, plantes et animaux, mais sont absentes du tractus digestif humain. Ces travaux portent sur les caractéristiques enzymatiques et la régulation de l’expression de deux &#61537;-galactosidase, Aga1 et Aga2, de R. gnavus E1. L’analyse bioinformatique de leur environnement génétique respectif indique une organisation simple pour Aga1 tandis qu’Aga2 est organisée en opéron. Elles ont été exprimées en système hétérologue chez E. coli, purifiées et leurs propriétés biochimiques ainsi que leurs spécificités de substrat ont été analysées. Le profil de croissance de la souche indique une préférence pour des substrats complexes (raffinose et mélbiose) faisant intervenir les a-galactosidase pour leurs utilisations ainsi que leur assimilation. / Ruminococcus gnavus E1 belongs to the Firmicutes, one of the two dominant groups in the human gut microbiota. a-galactosidases are glycoside hydrolases (GH) active on a-galactoside containing substrates. They are widely distributed through all the domains of life: bacteria, fungi, plants, and animals, but are absent from the human gastro-intestinal tract.Here we report the enzymatic characteristics and regulation of expression for two GH36 &#61537;-galactosidases, Aga1 and Aga2, from R. gnavus E1. Bioinformatics analysis of their respective genetic environment showed a different organisation, Aga1 having a simple organisation while Aga2 is organised as part of an operon. They were heterologously expressed in Escherichia coli, purified to homogeneity and their biochemical properties and substrate preferences comparatively analysed. The growth pattern of the strain in minimum media demonstrates a preference for complex substrates (melibiose and raffinose) that require the expression of the a-galactosidases for their utilisation and assimilation

<p>Curiosity is a powerful tool, and combined with the ability to observe the natural world, grants humankind an unique opportunity, the opportunity to wonder why. Why do things exist?, why do they do the things they do?, why is this even possible?</p> <p>Research in our lab is focused on the basic understanding and potential application of biological materials, in particular, biological adhesives produced by marine organisms such as oysters. Oysters produce a cement-like material that is able to withstand the dynamic conditions found in coastal environments. The focus of this dissertation is to lay the basis of the characterization of new biological materials by observing and analyzing its physical properties, to measure the performance of the material in natural conditions and finally to identify the basic components that give the material the properties that we observe. The end goal of this project is to understand the properties of this material so we are able to develop a synthetic system that is able to imitate, as close as possible, what we find in nature. These results, and more importantly, the new questions that emerge from this research, provide a first look at the adhesive system of oysters leading the way to new discoveries in the future.</p>

The present doctoral thesis summarises results of investigation focused on the characterisation of materials involved in Solid Oxide Cell technology. The main topic of investigation was the ceramic cell, also known as MEA. Particular attention was given to the role that bi-material interfaces, co-sintering effects and residual stresses play in the resulting mechanical response. The first main goal was to investigate the effects of the manufacturing process (i.e. layer by layer deposition) on the mechanical response; to enable this investigation, electrode layers were screen-printed one by one on the electrolyte support and experimental tests were performed after every layer deposition. The experimental activity started with the measurement of the elastic characteristics. Both elastic and shear moduli were measured via three different techniques at room and high temperature. Then, uniaxial and biaxial flexural strengths were determined via two loading configurations. The analysis of the elastic and fracture behaviours of the MEA revealed that the addition of layers to the electrolyte has a detrimental effect on the final mechanical response. Elastic characteristics and flexural strength of the electrolyte on the MEA level are sensibly reduced. The reasons behind the weakening effect can be ascribed to the presence and redistribution of residual stresses, changes in the crack initiation site, porosity of layers and pre-cracks formation in the electrode layers. Finally, the coefficients of thermal expansion were evaluated via dilatometry on bulk materials serving as inputs for finite elements analyses supporting experiments and results interpretation. The second most important goal was to assess the influence of operating conditions on the integrity of the MEA. Here interactions of ceramic–metal interfaces within the repetition unit operating at high temperatures and as well at both oxidative and reductive atmospheres were investigated. The elastic and fracture responses of MEA extracted from SOC stacks after several hours of service were analysed. Layer delamination and loss of mechanical strength were observed with increasing operational time. Moreover, SEM observations helped to detect significant microstructural changes of the electrodes (e.g. demixing, coarsening, elemental migration and depletion), which might be responsible for decreased electrochemical performances. All the materials presented in this work are part of SOC stacks produced and commercialised by Sunfire GmbH, which is one of the world leading companies in the field.

Ultra high molecular weight polyethylene (UHMWPE) is a polymer commonly used in various applications, particularly in hip joint replacements. Despite its good performance, it is susceptible to oxidation degradation, which can be mitigated with the addition of vitamin E, and to excessive wear against metal countersurfaces, which can potentially be improved with the addition of nanoparticles. In this work, sixteen newly developed UHMWPE nanocomposites with different nanofillers (multi-walled carbon nanotubes, graphene oxide and nanodiamonds), blended with and without vitamin E, and both irradiation crosslinked and non-crosslinked were studied. Thermomechanical characterisation (dynamic mechanical analysis and thermogravimetric analysis) and tribological pin-on-disc testing showed that both nanofillers and the addition of vitamin E ensured improved the performance of the nanocomposites compared to the virgin UHMWPE. Vitamin E improved the oxidative and thermal stability of UHMWPE, decreased the wear and increased the coefficient of friction. The nanoparticle reinforcements contributed to improved thermal stability to some degree and decreased the wear. Crosslinking was also shown to result in improved thermomechanical performance, although it appears that the addition of vitamin E inhibits the crosslinking process.

A Programação Orientada a Aspectos (POA) é uma técnica contemporânea de desenvolvimento de software fortemente baseada no princípio da separação de interesses. Ela tem como objetivo tratar de problemas de modularização de software por meio da introdução do aspecto como uma nova unidade de implementação que encapsula comportamento relacionado aos interesses transversais do software. A despeito dos benefícios que podem ser alcançados com o uso da POA, seus mecanismos de implementação representam novas potenciais fontes de defeitos que devem ser tratados durante a fase de teste de software. Nesse contexto, o teste de mutação consiste em um critério de seleção de testes baseado em defeitos que tem sido bastante investigado para demonstrar a ausência de defeitos pré-especifiados no software. Acredita-se que o teste de mutação seja uma ferramenta adequada para lidar com as particularidades de técnicas de programação contemporâneas como a POA. Entretanto, até o presente momento, as poucas iniciativas para adaptar o teste de mutação para o contexto de programas orientados a aspectos (OA) apresentam cobertura limitada em relação aos tipos de defeitos simulados, ou ainda requerem adequado apoio automatizado e avaliações. Esta tese visa a mitigar essas limitações por meio da definição de uma abordagem abrangente de teste de mutação para programas OA escritos na linguagem AspectJ. A tese inicia como uma investigação da propensão a defeitos de programas OA e define uma taxonomia de defeitos para tais programas. A taxonomia inclui uma variedade de tipos de defeitos e serviu como base para a definição de um conjunto de operadores de mutação para programas OA. Suporte automatizado para a aplicação dos operadores também foi disponibilizado. Uma série de estudos quantitativos mostra que a taxonomia de defeitos proposta é suficiente para classificar defeitos encontrados em vários sistemas OA. Os estudos também mostram que os operadores de mutação propostos são capazes de simular defeitos que podem não ser relevados por conjuntos de teste pré-existentes, não derivados para cobrir mutantes. Além disso, observou-se que o esforço requerido para evoluir tais conjuntos de teste de forma a torná-los adequados para os requisitos gerados pelos operadores / Aspect-Oriented Programming (AOP) is a contemporary software development technique that strongly relies on the Separation of Concerns principle. It aims to tackle software modularisation problems by introducing the aspect as a new implementation unit to encapsulate behaviour required to realise the so-called crosscutting concerns. Despite the benefits that may be achieved with AOP, its implementation mechanisms represent new potential sources of faults that should be handled during the testing phase. In this context, mutation testing is a widely investigated fault-based test selection criterion that can help to demonstrate the absence of prespecified faults in the software. It is believed to be an adequate tool to deal with testing-related specificities of contemporary programming techniques such as AOP. However, to date, the few initiatives for customising the mutation testing for aspect-oriented (AO) programs show either limited coverage with respect to the types of simulated faults, or a need for both adequate tool support and proper evaluation. This thesis tackles these limitations by defining a comprehensive mutation-based testing approach for AO programs written in the AspectJ language. It starts with a fault-proneness investigation in order to define a fault taxonomy for AO software. Such taxonomy encompasses a range of fault types and underlay the definition of a set of mutation operators for AO programs. Automated tool support is also provided. A series of quantitative studies show that the proposed fault taxonomy is able to categorise faults identified from several available AO systems. Moreover, the studies show that the mutation operators are able to simulate faults that may not be revealed by pre-existing, non-mutation-based test suites. Furthermore, the effort required to augment the test suites to provide adequate coverage of mutants does not tend to overwhelm the testers. This provides evidence of the feasibility of the proposed approach and represents a step towards the practical fault-based testing of AO programs