Thesis (MScAgric (Soil Science)--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: A number of chemical and physical features of Namibian soils in a 22 790 km2, two degree-square block between 17 – 19 oE and 22 – 23 oS in eastern central Namibia, had been investigated, and the fertility status established. In 80 % of samples the nitrate, nitrite, and sulfate concentrations of the saturated paste extract are 0 – 54.6 mg l-1 NO3 -, 0 – 24.7 mg l-1 NO2 -, and 5.4 – 20.9 mg l-1 SO4 2- respectively. In 90 % of samples the plantavailable phosphorus is below 12 mg kg-1, which is low for a soil under natural grassland, but in line with the prevailing semi-arid climate and low biomass production of the study area. In 80 % of samples the extractable calcium, magnesium, potassium, and sodium concentrations are 0.61 – 5.73 cmolckg-1 Ca (122 – 1 146 mg kg-1 Ca), 0.12 – 2.28 cmolckg-1 Mg (15 – 278 mg kg-1 Mg), 0.13 – 0.54 cmolckg-1 K (51 – 213 mg kg-1 K) and 0.05 – 0.38 cmolckg-1 Na (11 – 87 mg kg-1 Na) respectively, while the exchangeable calcium, magnesium, potassium, and sodium concentrations are 0.21 – 6.02 cmolckg-1 Ca, 0.12 – 2.01 cmolckg-1 Mg, 0.12 – 0.49 cmolckg-1 K and 0 – 0.13 cmolckg-1 Na respectively. The mean ± 1 standard deviation is 3.57 ± 3.57 cmolckg-1 for cation exchange capacity, 3.48 ± 3.61 for sum of exchangeable bases and 4.53 ± 4.39 for sum of extractable bases. The cation exchange capacity and the sum of exchangeable bases are virtually identical, which indicate the almost complete absence of exchangeable H+ and Al3+ in the soils of the study area, as expected from a semi-arid climate. None of the profiles were classified as saline or sodic. In 80 % of samples the plant-available iron, manganese, zinc and copper concentrations are 7.2 – 32.8 mg kg-1 Fe, 13.6 – 207.5 mg kg-1 Mn, 0 – 1.80 mg kg-1 Zn and 0 – 4.0 mg kg-1 Cu respectively. Soil organic matter content of the study area soils ranges between 0.05 – 2.00 %, with most (80 % of samples) containing 0.25 – 1.20 % organic matter. This is considerably lower than values reported in literature, even for other southern African countries. The reason lies with the hot, semi-arid climate. The pH distribution is close to normal, with 80 % of samples having pH (H2O) of 5.54 – 8.18, namely moderately acid to moderately alkaline. Sand, silt and clay content of most (80 %) samples varies between 60.3 – 89.7 % sand, 4.6 – 25.2 % silt and 3.5 – 19.1 % clay. The soils of the study area are mainly sandy, sandy loam and loamy sand. In 80 % of samples the coarse sand fraction ranges from 3.5 – 34.5 %, the medium sand fraction from 20.5 – 37.3 %, the fine sand fraction from 38.7 – 54.5 % and the very fine sand fraction from 0.0 – 12.9 % of all sand. The fine sand fraction, thus, dominates, with very fine sand being least abundant. The topsoil contains relatively more coarse sand and less very fine sand than the subsoil. Instances of sealing, crusting and hardening occur sporadically in the study area. Cracking is only found in pans, while self-mulching is not evident. No highly instable soils were encountered in the study area. The water-holding capacity is generally low, with depth limitations in the western highlands, the Khomas Hochland, and texture limitations in the eastern Kalahari sands. The central area has soils with a somewhat better water-holding capacity, but it is still very low when compared to arable soils of temperate, sub-humid and humid zones elsewhere in southern Africa. Soil characteristics are perceptibly correlated with climate, parent material, topography, degree of dissection of the landscape and position in the landscape. The most obvious differences are between soils formed in schistose parent material of the Khomas Hochland in the west and those of the Kalahari sands in the east. The soils of the study area are unsuitable to marginally suitable for rainfed crop production, due to low iv fertility. The study area is climatologically unsuited for rainfed crop production, so the present major land use is extensive livestock production on large farms. The natural vegetation is well adapted to the prevailing conditions. The methodology followed to delineate terrain units, with a combination of procedures involving digital elevation data and satellite imagery, seems to work well in the Namibian landscape. This study thus served as a successful proof-of-concept for the methodology, which can in future be rolled out for the remainder of the country. The site and analytical information is available in digital format as spreadsheets and in a geographical information system, as well as in a variety of digital and printed maps. / AFRIKAANSE OPSOMMING: ‘n Aantal chemiese en fisiese eienskappe van Namibiese gronde in ‘n 22 790 km2, 1o x 2o blok tussen 17 – 19 o Oos en 22– 23 o Suid in oostelike sentraal-Namibië is ondersoek en die grondvrugbaarheidstatus bepaal. In 80 % van monsters is die nitraat-, nitriet- en sulfaatkonsentrasies van die versadigde pasta ekstrak 0.0 – 54.6 mg l-1 NO3 -, 0.0 – 24.7 mg l-1 NO2 -, en 5.4 – 20.9 mg l-1 SO4 2-onderskeidelik. In 90 % van monsters is die plant-beskikbare fosfor minder as 12 mg kg-1, wat laag is vir gronde onder natuurlike grasveld, maar dit is verklaarbaar deur die heersende semi-ariede klimaat en lae biomassa produksie in die studiegebied. In 80 % van monsters is die konsentrasies van ekstraheerbare kalsium, magnesium, kalium en natrium 0.61 – 5.73 cmolckg-1 Ca (122 – 1 146 mg kg-1 Ca), 0.12 – 2.28 cmolckg-1 Mg (15 – 278 mg kg-1 Mg), 0.13 – 0.54 cmolc kg-1 K (51 – 213 mg kg-1 K) en 0.05 – 0.38 cmolckg-1 Na (11 – 87 mg kg-1 Na) onderskeidelik, terwyl die uitruilbare kalsium, magnesium, kalium en natrium konsentrasies onderskeidelik 0.21 – 6.02 cmolckg-1 Ca, 0.12 – 2.01 cmolckg-1 Mg, 0.12 – 0.49 cmolckg-1 K and 0.0 – 0.13 cmolckg-1 Na is. Die gemiddelde ± 1 standaardafwyking is 3.57 ± 3.57 cmolckg-1 vir katioonuitruilvermoë, 3.48 ± 3.61 vir die som van uitruilbare basisse en 4.53 ± 4.39 vir die som van ekstraheerbare basisse. Die katioonuitruilvermoë en som van uitruilbare basisse is feitlik identies, wat ‘n feitlik algehele afwesigheid van uitruilbare H+ and Al3+ in die gronde van die studiegebied aandui, soos verwag word weens die semi-ariede klimaat. Geeneen van die profiele is geklassifiseer as soutbrak of natriumbrak nie. In 80 % van monsters is die plant-beskikbare yster, mangaan, sink en koper konsentrasies onderskeidelik 7.2 – 32.8 mg kg-1 Fe, 13.6 – 207.5 mg kg-1 Mn, 0.0 – 1.80 mg kg-1 Zn en 0.0 – 4.0 mg kg-1 Cu. Grond organiese material inhoud in die studiegebied wissel tussen 0.05 – 2.00 %, met 80 % van monsters wat 0.25 – 1.20 % organiese material bevat. Dit is aansienlik laer as die waardes gevind in literatuur, selfs vir ander Suider-Afrikaanse lande. Die oorsaak is die warm, semiariede klimaat. Die pH verspreiding is feitlik normaal, met 80 % van monsters wat pH (H2O) van 5.54 – 8.18 het, met ander woorde matig suur tot matig alkalies. Sand, slik en klei inhoud van die meeste (80 %) monsters varieer tussen 60.3 – 89.7 % sand, 4.6 – 25.2 % slik en 3.5 – 19.1 % klei. Die gronde van die studiegebied is hoofsaaklik sand, sand-leem en leem-sand. In 80 % van monsters beslaan die growwe sandfraksie 3.5 – 34.5 %, die medium sandfraksie 20.5 – 37.3 %, die fyn sandfraksie 38.7 – 54.5 % en die baie fyn sandfraksie 0.0 – 12.9 % van die totale sandfraksie. Die fyn sandfraksie is dus dominant, terwyl die baie fyn sandfraksie die skaarsste is. Die bogronde bevat relatief meer growwe sand en minder baie fyn sand as die ondergronde. Gevalle van verseëling, korsvorming en verharding kom sporadies in die studiegebied voor. Krake kom net in panne voor en self-omkering is nie opgemerk nie. Geen hoogsonstabiele gronde is in die studiegebied gevind nie. Die waterhouvermoë is in die algemeen laag, met dieptebeperkinge in die westelike hooglande, die Khomas Hochland, en tekstuurbeperkinge in die oostelike Kalahari sande. Die sentrale gedeelte het gronde met ‘n ietwat beter waterhouvermoë, maar dis steeds baie laag in vergelyking met akkerbougronde van gematigde, sub-humiede en humiede sones elders in Suider- Afrika. Grondeienskappe is ooglopend verwant aan klimaat, moedermateriale, topografie, graad van gebrokenheid van die landskap en posisie in die landskap. Die duidelikste verskille kom voor in die gronde wat van vi skisagtige moedermateriaal van die Khomas Hochland in die weste en dié wat in die Kalahari sande in die ooste gevorm het. Die gronde van die studiegebied is ongeskik tot marginaal geskik vir droëland akkerbou, weens die lae vrugbaarheid. Aangesien die studiegebied klimatologies ongeskik is vir droëland akkerbou, is die huidige hoof landgebruik ekstensiewe veeproduksie op groot plase. Die natuurlike plantegroei is goed by die heersende omstandighede aangepas. Die metodiek wat gevolg is om terreineenhede af te baken, wat ‘n kombinasie van prosedures met digitale hoogtedata en satellietbeelde is, blyk goed te werk vir die Namibiese landskap. Hierdie studie dien dus as ‘n suksesvolle bewys-van-konsep van die metodiek, wat in die toekoms uitgebrei kan word na die res van die land. Die veld- en ontledingsinligting is beskikbaar in digitale formaat, in ‘n geografiese inligtingstelsel en ‘n verskeidenheid digitale- en gedrukte kaarte.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: With the depletion of high quality conventional materials for road pavements, the consideration of cement stabilisation for sub-base and base layer materials often provide a feasible solution to the road industry. Like all pavement material types, the design inputs should be determined using reliable test methods, which provide a good indication of the property of materials. Any evaluation should provide a better understanding of the engineering and behavioural properties of the materials. This should form the basis for ascertaining their suitability for use in the pavement structure. However, the road industry is dependent on strength testing of cement-stabilised materials as a means to ascertain material suitability for use. Strength alone does not offer reliable insight regarding the performance and durability of the stabilised layer. This is because a cement-stabilised layer may be very stiff but not strong enough to withstand the loading and endure adverse environmental conditions. Similarly, the stabilised layer may be prone to cracking emanating from shrinkage, which leads to performance and durability related distresses. A stabilised sub-base and base of the pavement structure experiences tensile stresses and strains under traffic loading. At laboratory level, the flexural beam test simulates to an acceptable degree the mode of stress to strain to which the pavement layer experiences. However, the test lacks a standard test protocol. This leads to inconsistencies while evaluating the same material type. Due to this fact, the formulation of a standard laboratory test procedure is necessary. Shrinkage cracking is one of the major causes of pavement failure. The manifestation of wide cracks leads to performance related distresses. Cracks provide zones for the infiltration of water into the underlying layers, an aspect that results in further deterioration of the pavement structure. However, the evaluation of shrinkage at laboratory level is not usually undertaken. Disregarding shrinkage evaluation stems from the fact that a number of guidelines consider it as a natural material characteristic. The road industry frequently depends on the use of low cement contents among other techniques as a means to mitigate shrinkage cracking in cement-stabilised layers. The selection of a mitigation measure usually lacks reliable data concerning the material’s shrinkage potential. Because of this, the requirement to evaluate shrinkage at laboratory level as part of a material property measure provides a good indication regarding the quality of material. Nanotechnology products such as the Nanotterra Soil® a polymer cement additive are purported to mitigate shrinkage cracking in cement-stabilised layers. However, their suitability for use remains unspecified and dependent on the stakeholders. With the development of a shrinkage method, the evaluation of shrinkage reducing products can be undertaken. This research proposes a flexural beam test protocol for cement-stabilised materials, comprising of a span-depth ratio of nine or greater as fitting to provide a reliable measure of the material’s flexural strength and elastic modulus. The developed shrinkage test method provides a good repeatability and is user friendly. The test provides a good indication of the shrinkage criteria of ferricrete and hornfels with and without the polymer. The efficacy of the polymer is dependent on the cement content in the mix and the type and quality of the material. The research provides insight pertaining to the characterisation of shrinkage, behavioural properties, and durability of cement-stabilised materials. Analysis of the shrinkage crack pattern reveals that use of the polymer lessens the development of tensile stress in a cement-stabilised layer. Equally, the application of the low cement contents for stabilisation may not result in cracking of the stabilised layer. This research contributes to a better understanding of cement-stabilised materials. / AFRIKAANSE OPSOMMING: Namate hoë kwaliteit konvensionele materiale uitgeput raak, word sementstabilisasie van stutlaag en kroonlaag materiale al hoe meer oorweeg en is dit ʼn geskikte oplossing vir die padbou-nywerheid. Soos vir alle padboumateriale moet die ontwerpeienskappe bepaal word deur middel van betroubare toetsmetodes wat ʼn goeie aanduiding van die materiaal se eienskappe sal gee. Enige evaluering moet ʼn beter insae in die materiaal se ingenieurseienskappe en gedrag oplewer. Dit moet dan die basis vorm om die materiaal se gebruik in ʼn padstruktuur te evalueer. Die padbou-nywerheidmaak grootliks staat op die toetsing van skuifsterkte van sementgestabiliseerde materiaal om die geskiktheid daarvan vir gebruik te bepaal. Sterkte op sigself lewer egter nie ʼn betroubare maatstaf van die materiaal se gedrag en duursaamheid nie. Dit is aangesien ʼn sementgestabiliseerde laag baie solied mag wees maar nogtans nie sterk genoeg om belasting te weerstaan en bestand teen omgewingstoestande te wees nie. Net so mag ʼn gestabiliseerde laag vatbaar vir kraakvorming as gevolg van krimping wees en dit kan lei tot duursaamheid-verwante en werkverwante skade. ʼn Gestabiliseerde stutlaag en kroonlaag in die plaveiselstruktuur is onderhewig aan trekspannings en vervormings as gevolg van verkeerslaste. Op laboratoriumvlak boots die balkbuigtoets die spanning en vervorming wat ʼn plaveisellaag ondervind tot ʼn aanvaarbaar hoë mate na. Die toets beskik nie oor ʼn standaard-toetsprosedure nie. Dit lei tot afwykings terwyl dieselfde materiaal evalueer word. Om hierdie rede is die ontwikkeling van ʼn standaard-laboratoriumprosedure nodig. Krimpkraking is een van die grootste oorsake van plaveiselswigting. Die onwikkeling van wye krake lei tot werksverwante skade. Krake veroorsaak areas vir die infiltrasie van water in die onderliggende plaveisellae wat verdere agteruitgang van die plaveiselstruktuur veroorsaak. Desnieteenstaande word ʼn evaluering van kraking op laboratoriumvlak selde gedoen. Dit spruit uit die feit dat ʼn aantal ontwerp-riglyne kraking as ʼn natuurlike materiaaleienskap beskou. Die padbounywerheid moet dikwels staatmaak, op onder andere, ʼn lae sementinhoud om krimpkraking te minimeer. Hierdie tipe benadering gaan dikwels mank aan betroubare inligting oor die materiaal se krimpingspotensiaal. Om hierdie rede is die ondersoek van krimping op laboratoriumvlak nodig as deel van die ondersoek van die materiaaleienskappe om die kwaliteit van materiale te bepaal. Minimeringstegnieke verander deurlopend. Die toepassing van nanotegnologieprodukte, soos Nanotterra Soil®, ‘n polimeersement bymiddel, wat na bewering krimpkraking in sementgestabiliseerde lae kan minimeer, kom voortdurend op die mark. Nogtans bly hulle geskiktheid ongespesifiseerd en afhanklik van die leweransiers. Indien ʼn krimptoetsmetode ontwikkel word, sal die effektiwiteit van krimpverminderingsmiddels getoets kan word. Hierdie navorsing stel die ontwikkeling van ʼn toetsprosedure vir ʼn balkbuigtoets voor met ʼn spanlengte tot diepteverhouding van minstens nege as betroubare maatstaf van ʼn materiaal se buigsterkte en modulus van elastisiteit. Die ontwikkelde krimptoetsmetode lewer ʼn goeie herhaalbaarheid en is gebruikersvriendelik. Die toets verskaf ʼn goeie aanduiding van krimpingskriteria van ferrikreet en horingfels met en sonder polimeer. Die effektiwiteit van die polimeer hang af van die sementinhoud in die mengsel asook die tipe en kwaliteit van die materiaal. Die navorsing verskaf insig aangaande die karakterisering van krimping, gedragseienskappe en duursaamheid van sementgestabiliseerde materiale. Die navorsing help mee om sementgestabiliseerde materiale beter te verstaan.

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.