The diploma thesis describes the design and assessment of steel footbridge for pedestrians and cyclists across the river Svratka in Brno. As the main material of structural elements was used steel S355. In the beginning is deal with two variants of structural system, which are compared with each other and the better variant is chosen. The main structural system of chosen variant consist of two parabolic arches bend down to each other on which is suspended by suspenders intermediate deck. The deck consist of two steel beams with floor beams and composite cencrete slab. The span length is 50 m.

The importance of practical activities has been outlined in many articles and research studies. This study presents the way in which two novice and two expert teachers conduct practical activities in their intermediate phase in Natural Sciences and Technology (NST) classrooms and the challenges they face. This study was conducted in primary schools because researchers such as Mihret (2014, p.2) believe that "primary level science education is a cornerstone to lay a foundation to get young citizens interested in science". This study utilised a qualitative case study approach. The data was collected through classroom observations, open ended interviews and document analysis. The population of this study consisted of primary school teachers teaching Natural Sciences and Technology. The participants included two novice teachers and two expert teachers. The conceptual framework that guided this study emerged from the literature review. The conceptual framework of this study was based on concept of practical activity and the four pillared cognitive design framework. The findings of this study indicated that the way that novice and expert teachers conduct practical activities differ and they face different challenges when conducting practical activities. Novice teachers conduct teacher centred activities, they do not allow their learners to conduct independent practical activities, they use practical activities as a way to remind learners of the work done in the classroom and they mostly use previously developed worksheets during practical lessons. Expert teachers on the other hand conduct learner centred practical activities, they allow their learners to work independently and they do not always use worksheets in their practical activities. The findings also indicated that novice teachers face more challenges in their practical lessons than expert teachers. Novice teachers find it difficult to manage their learners' behaviour during practical lessons, they did not have confidence in their learners and they did not have effective disciplinary strategies. However, both novice and expert teachers had a challenge managing their time during their practical lessons. / Dissertation (MEd)--University of Pretoria, 2016. / Science, Mathematics and Technology Education / MEd / Unrestricted

In this project, samples with a metal/semiconductor/metal structure were fabricated and investigated with the potential application as the interconnecting layer of a tandem solar cell in mind. Degenerately doped p-Si and n-Si were used as bottom (metal like) contacts, as Si represents one of the most common materials for the bottom cell of tandem devices. A transparent, wide bandgap semiconductor in the form of SnO₂ was investigated for the intermediate layer as it is a common choice for the selective back contact of top cells based on perovskites. However, atomic layer deposition (ALD) was used as an alternative to the typical solution based application of the SnO₂ layer. The top layer was simply chosen as a triple layer metal contact stack (Ni-Al-Ni) to provide for good contact with the SnO₂.The goal of the project was to study the electrical properties of the samples through I-V measurements and how the I-V characteristic depends on the oxide’s thickness under the possible influence of the contact areas. Three different thicknesses of the SnO2 layer were used for the p-Si sample: 50, 200 and 400 Å. For the n-Si samplesonly one thickness (400 Å) was studied. Using the diode equation, four parameterswere calculated (Jo, Rsh, Rs and n) for different measurements combing different contact configurations. The latter included measurements between the front and the back of the samples and measurements between contacts on the front with and/orwithout SnO2 layer. From the results, it was concluded that as the thickness of SnO₂ increases, the saturation current (Jo) decreases while both shunt resistance (Rsh) andseries resistance (Rs) increase. The ideality factor (n) neither depends significantly on effective area, nor on SnO2 thickness. The p-Si and n-Si samples show similar behavior in the case of 400 Å SnO2 thickness. The contact areas only appreciatively affect Jo, but it is not clear what lies behind this dependence. In all cases, the top contacts obtained major wear during measurements, reducing the number of trustworthy measurements that could be used on the smaller areas. The resistivity through the oxide layer was calculated to ρSnO₂ = 247±96 MΩ cm, which is higher than for SnO₂ deposited by other techniques, and too high for tandem cell application. Schottky barriers formed at the interfaces will typically limit the charge transport further.

Motivation behind the spring whale shark (Rhincodon typus) aggregation in Al-Lith, on the Saudi Arabian coast of the South Central Red Sea, is uncertain. A plausible hypothesis is that whale sharks gather to feed on high prey density, leading to questions about the cause of the prey density. A bottom-up process fueled by nutrient input or accumulation from physical advection could create a peak in prey biomass. Wastewater discharged from an aquaculture facility could affect productivity or provide a chemosensory cue for whale sharks. Yet, basic physico-biological oceanography of this region is unresolved. Monthly profiles, long-term moorings, and spatial surveys were used to describe the temporal variability of potential prey biomass and water masses in this region for the first time. Plankton abundance of individuals larger than ~0.7 cm did not peak during whale shark season. Rather, a decrease coinciding the trailing end of whale shark detections was observed. Sites 180 m apart had differences in acoustic backscatter, suggesting small-scale biomass patchiness, supporting the small-scale variability in whale shark habitat selectivity. Red Sea Deep Water, a nutrient-rich water mass formed in the northern Red Sea, appeared in July at the same time the Tokar wind jet from the Sudanese mountain gap is the highest. Gulf of Aden Water, a nutrient-rich water mass from the Indian Ocean, arrived as episodes from May to September, contrary to previous expectations that the water arrives continuously. It is unlikely that these natural nutrient sources are directly responsible for the high prey density attracting the whale sharks. The aquaculture plume, observed at the aggregation site, had a distinct seasonality from the ambient waters. The plume’s highest salinity (>48) approached the extreme limits of coral tolerances. Nutrient concentrations (nitrate, nitrite, phosphate, silica), suspended particulate matter, phytoplankton biomass, bacteria and cyanobacteria cell counts, total nitrogen, and relative abundance of genera associated with opportunistic pathogenic species (e.g., Arcobacter) were significantly higher in the plume. This study was the first to estimate the nutrient flux and spatial variability of the aquaculture plume.

We report on some experience with a parallel version of the Gröbner basis algorithm with factorization, implemented in the REDUCE package CALI [4]. It is based on a coarse grain parallel master-slave model with distributed memory. This model was realized on an HP workstation cluster both with a disk remote connection based on (ordinary) REDUCE [9] and the special PVM-based parallel REDUCE version of H. Melenk and W. Neun [7]. Our considerations focus on a detailed study of the practical time behaviour of the parallelized improved Gröbner factorization algorithm [5]. For well splitting examples, where the number of intermediate subproblems is large compared to the number of parallel processes available on the system (only for such examples this approach makes sense), we've got almost always a good load balance. Since even for the relative slow disk remote connection the results are encouraging, we conclude that with a fast and stable communication hard- and software one will obtain a serious speed up on such problems compared to the serial implementation.

Diseases caused by bacteria, fungi and viruses pose a significant threat especially to poor rural communities. Viral infections are frequently complicated by secondary bacterial and fungal infections which remain a major challenge globally and in particular, in sub Sahara Africa amongst humans and animals alike. The main aim of this study was to develop a low toxicity plant extract or isolated compound active against viral, bacteria and fungal pathogens from selected plant species. Seven tree species that were investigated were Acokanthera schimperi, Carissa edulis, Ekebergia capensis, Podocarpus henkellii, Plumbago zeylanica, Annona senegalensis and Schrebera alata traditionally used in the treatments of various ailments were selected and extracted using solvents of varying polarity. Extracts of selected plants were tested for activity against two Gram positive and two Gram negative bacterial namely Enterococcus faecalis and Staphylococcus aureus and two Gram-negative species, Pseudomonas aeruginosa and Escherichia coli respectively, three fungal pathogens: Candida albicans, Cryptococcus neoformans and Aspergillus fumigates and four enveloped animal viruses: feline herpes virus–1 (FHV-1, dsDNA), canine distemper virus (CDV, ssRNA), canine parainfluenza virus-2 (CPIV-2, ssRNA) and lumpy skin disease virus strain V248/93 (LSDV, dsDNA). The presence of antioxidant constituents in the different extracts and cytotoxicity against three cell types CRFK, bovine dermis and Vero cells were determined. Bioautography and the serial microplate dilution methods were used to determine the number of antimicrobial compounds and antimicrobial activity of extracts against bacterial and fungal pathogens. Virucidal and attachments assays were used to determine the activity against viral pathogens. Qualitative antioxidant activities of extracts were tested using the DPPH reagent and cytotoxicity using the MTT assay. Biological activity was observed in all the extracts against one or more organisms on bioautography. The intermediately polar system (CEF) separated more active constituents. Some extracts had compounds with similar Rf values active against one or more organisms. In both the antibacterial and antifungal assays, acetone extracts had the highest activity followed by DCM against one or more pathogens. Hexanes extracts were the least active. P. henkellii extracts had more active compounds against the bacteria and Annona senegalensisagainst the fungi. In the micro-dilution assay, S. aureus was the most susceptible bacterial organism to extracts of the different plant, followed by P. aeruginosa andEscherichia coli, and E. faecalis the least. C. neoformans on the other hand was the most susceptible fungal pathogen. In the antiviral assay, although activity was observed with hexane extracts of some plants in the virucidal assay, the most potent inhibition was observed with the acetone and methanol extracts of Podocarpus henkelii against CDV and LSDV in the virucidal assay and acetone extracts in the attachment assay. In general the hexane was the least toxic while the intermediate polarity extracts were generally the most toxic indicating that highly polar compounds were possibly poorly or highly absorbed through membranes in the former and later respectively. Of the three cell types used CRFK was the most sensitive followed by bovine dermis and Vero cells the least. Cytotoxicity studies of extracts of the different plants revealed A. senegalensis and A. schimperi extracts were the most toxic plants in the cellular assay. These plants are toxic to animals and the cytoxicity is in line with the in vivo toxicity. The protective effects of antioxidant constituents in some extracts varied and appear to be influenced by the metabolism of the type of cell in culture. It also appears to suggest that metabolism in kidney derived cells can be influenced by species variation in the origin of cells. P. henkellii was selected for isolation of bioactive compound. Three compounds were isolated and their structure elucidated using 13C and 1H NMR and mass spectrometric data. The antibacterial, antifungal and antiviral activity of the isolated compounds 7’, 4’, 7’’, 4’’’, tetramethoxy amentoflavone (C1), isoginkgetin (C2) and Podocarpusflavone–A (C3) were determined. Compound C2 was the most active against E. coli and S. aureus (MIC = 60 ìg/mE) and a selectivity index (SI) value of 16.67. The compound was also active against A. fumigatus and C. neoformans (SI = 33.33) suggesting both antibacterial and antifungal activity with relative safety. Compound C3 had a broad spectrum of activity against E. faecalis and P. aeruginosa with SI values of 4. A less potent activity of the compounds was obtained in both the virucidal and attachment assays against test pathogens, indicating the lower activity of the compounds against tested viral pathogens. The studies further suggest structural activity relationship in the antimicrobial activity of biflavonoids. The compounds C1 and C2 had no toxic effect on the three cell types and mutagenicity studies indicated no activity of these compounds. Podocarpusflavone-A occurs in every species of Podocarpus so far investigated, except P. latifolius. These studies represent the first isolation of bioactive compounds from P. henkellii. Although a different extractant was used than that used by traditional healers, the presence of antiviral compounds in Podocarpus henkelii against two unrelated viruses may justify on a chemotaxonomic basis the traditional use of related species Podocarpus latifoliusand Podocarpus falcatus in the traditional treatment of canine distemper infection in dogs. / Thesis (PhD)--University of Pretoria, 2011. / Paraclinical Sciences / unrestricted

No description available.

Modelling and simulation of the human body during an impact situation such as a car accident, can lead to better designed safety features on vehicles. In order to achieve this, investigation into the material properties and the creation of a numerical model of cortical bone is needed. One approach to creating a material model of cortical bone suitable for these situations is to describe the material model as visco-elastic, as reported by Shim et al. [1], Bekker et al. [2] and Cloete et al. [3]. The work by Shim et al. and Bekker et al. developed three-dimensional models, but do not accurately capture the transition in behaviour in the intermediate strain rate region, while Cloete et al. developed a phenomenological model which captures the intermediate strain rate behaviour in one dimension. This work aims to verify and extend these models. The intermediate strain rate regime (1 s−1 to 100 s−1 ) is of particular interest because it is a key characteristic of the behaviour of cortical bone and several studies have been conducted to gather experimental data in this region [3, 4, 5, 6]. The behaviour can be captured using non-linear viscoelastic models. This dissertation focuses on the development and implementation of a material model of cortical bone based on non-linear visco-elastic models to capture the intermediate strain rate regime behaviour. The material model was developed using uni-axial test results from cortical bone. The model by Cloete et al. has been improved and extended, and issues of local and global strain rate with regards to the viscosity have been clarified. A hereditary integral approach was taken in the analysis and implementation of discrete models and was found to be consistent with mathematical models. The model developed was extended to three dimensions in a manner similar to that of Shim et al. and Bekker et al. for implementation in commercial finite element software (LS-Dyna and Abaqus).

Thesis (M. Dev.) -- University of Limpopo, 2021 / Recent changes in the South African education department have led to many learners’ deviant behaviour in the classroom. The abolishing of corporal punishment has accelerated lack of discipline among learners in the Ehlanzeni education region. This challenge has resulted in different perceptions among the teachers. Hence, this study aims at investigating teachers’ perceptions of learner discipline in the intermediate phase schools of the Ehlanzeni Region of Mpumalanga province. In this study, the researcher uses the mixed approach, a method which includes both quantitative and qualitative research. Data is collected through survey and semi structured interviews with principals, deputy principals, heads of departments (HOD’s) and teachers. Stratified and purposive sampling methods were used to facilitate the above process. The findings show that factors such as abolishing of corporal punishment, lack of parental involvement, lack of extramural activities and lack of clarity on policy have negatively influenced discipline in the intermediate schools. Hence, there is a need for alternative strategies to enhance the implementation of new disciplinary measures in the intermediate schools. These anomalies call for senior management or policy makers in the Department of Education (DoE) to develop relevant alternative strategies and to train teachers on policy implementation before the new disciplinary measures can be employed. This will assist teachers to prevent ill-discipline in Mpumalanga.

Effect of an extraction method on the structure of glucan and its immunostimulatory response in Fenneropenaeus indicus was investigated. Here we extracted alkali insoluble glucan (AIG) and alkali soluble glucan (ASG) from a filamentous fungi Acremonium diospyri following alkali-acid hydrolysis and the sodium hypochlorite oxidation and dimethyl sulphoxide extraction method respectively. Structural analysis showed that 85% of glucan in AIG was a (1→3)-β-d-glucan and it increased the prophenoloxidase and reactive oxygen intermediate activity when administered to F. indicus. On the other hand, ASG, which contained 93% (1→3)-α-glucan, did not induce significant immune response in shrimp. Here we report that the difference in immunostimulatory potential between AIG and ASG is due to the difference in the percentage of (1→3)-β-d-glucans present in each preparation, which varies with the method of extraction employed. Also our observations suggest that glucan can be used as a potential immunostimulant to shrimp, provided it contains (1→3)-β-d-glucan as the major fraction.