Thesis (M. Ed. (Mathematics, Science and Technology)) --University of Limpopo, 2016 / The aim of the study was to explore factors which motivated girls to study Physical Sciences in Grade 10. The study followed a qualitative research paradigm and a case study design. A sample of twenty four girls from three secondary schools in Rakwadu Circuit in Limpopo province was purposively sampled for the study. Data was collected using interviews with Grade 10 girls who were studying Physical Sciences and Grade 9 girls who intended to study Physical Sciences in Grade 10. In addition, document analysis was used to analyse participants’ classwork, tests and other forms of assessments. The results show that these groups of girls were motivated by both external factors and internal factors. The factors included career opportunities that Physical Sciences offers, financial assistance, learner performance and interest in the subject. The study revealed that girls had positive attitudes towards science and wanted to pursue science related careers. The learning environment and family also played a role in motivating learners to study science. It is therefore recommended that parents, educators and the entire education sector support and motivate girls to assert their role in science.

Discotic liquid crystal research is now more than 30 years old, however it is still early days compared with the well-established area of calamitic liquid crystal research which dates back for more than a century. Since the 1990’s there has been great deal of interest in discotic liquid crystal research, due to applications such as discotic compensation films for enhancing liquid crystal display (LCD) viewing angles and exciting new potential applications such as organic semi-conductors and photovoltaics.The work contained in this thesis can be broken down into three major areas: investigation of synthetic methodologies of hexasubstituted triphenylene-based discotic liquid crystals, examination of structure-property relationships within novel triphenylene-based discotic liquid crystalline materials, and the design and mesomorphic properties of novel disc-shaped molecular architectures.The investigation of the synthetic methodologies of triphenylene-based liquid crystals examined two main areas of the synthesis of triphenylene-based discotic materials: iodination reactions to generate valuable intermediates, and the oxidative strategies and methods for the generation of hexasubstituted triphenylenes. These investigations have revealed that careful control over reaction conditions can offer great selectivity in the synthesis of halogenated intermediates for the synthesis of triphenylene-based liquid crystals and that electron rich intermediate species offer the greatest scope for the synthesis of hexasubstituted triphenylenes in good yield and purity.The determination of structure-property relationships within triphenylene-based discotic liquid crystals has examined various peripheral substituents and various near-core modifications to the conventional discotic liquid crystal.A small number of novel spiral-shaped materials have been synthesised, which have revealed interesting mesomorphic properties. These materials have shown the ability to self-organise in such a manner as to fill free space around central disc units so as to generate columnar mesophases in materials which would not otherwise be expected to exhibit mesomorphism.

Compared to 1-substituted-5-aminoimidazoles relatively few 1-substituted-5-hydroxyimidazoles have been reported; however, an interesting 1-substituted-5-hydroxyimidazole is the immunosuppressive agent bredinin, which shows antiviral, antimalarial, antitumour and antiarthritic activities. Bredinin is obtained naturally by extraction from a fermentation process, and current synthetic strategies for the synthesis are ambiguous and don’t easily allow for the synthesis of analogues. Surprisingly, relatively few analogues of bredinin are known hence a convenient route to such types of compounds would be useful in providing a library of compounds for structural activity studies to be made.The aim of the present study was to develop a synthetic strategy which employed inexpensive and readily available acyclic precursors to synthesise a library of analogues of bredinin. An advantage of using acyclic precursors to synthesise imidazoles is that the introduction of substituents, in particular, those in the 1-position is unambiguous. Therefore, our approach has been to explore an efficient and general route to 1-substitued-5-hydroxyimidazoles employing inexpensive and readily available startingmaterials.Our initial target was to synthesise ethyl 1-substituted-5-hydroxyimidazole-4-carboxylates since such ester intermediates have the potential to be converted to a wide variety of related 4-substituted imidazoles. A variety of ethyl 1-substituted-5-hydroxyimidazole-4-carboxylates were synthesised. Those synthesised using lipophilic amines at position 1 of the imidazole ring (structures 39-43), were obtained in high yields and easily purified. However, those synthesised using polar amines at position 1 (structures 43-45), were more difficult to isolate and purify due to their increased hydrophilic nature.In addition, the adopted strategy offers the opportunity to introduce a variety of substituents in the 2-position of the imidazole ring (structures 48-49), however this increase in chain length at position 2 had a direct effect on the yield of the imidazole obtained. The longer the chain length, the lower the yields, due to the steric hindrance experienced in the cyclisation step of the synthetic sequence.In summary a novel convergent synthetic strategy was devised and both ethyl 1,2-substituted-5-hydroxyimidazole-4-carboxylates, with both aryl and alkyl groups atposition 1, and benzyl 1-benzyl-5-hydroxyimidazole-4-carboxylate were successfully synthesised. Both lipophilicity and steric bulk were found to play a crucial role in the successful cyclisation and subsequent isolation and purification of the imidazoles, and a compromise between the two must be achieved to give the optimal reaction conditions.In an attempt to gain a greater understanding of these ethyl 1-substituted-5-hydroxyimidazole-4-carboxylates systems, their reactivity under different reactions conditions was assessed. Ethyl 1-benzyl-5-hydroxyimidazole-4-carboxylate was used as the model system and was found to be stable to all targeted manipulation at position 2 and 4 of the imidazole ring. Additionally, all attempts to protect the 5-hydroxyl function, to allow the subsequent manipulation of the ethyl ester, were also unsuccessful. The unexpected benzylation of the nitrogen at position 3 of the imidazole ring, to form the quaternary ammonium salt, confirms that this is the most nucleophilic atom within the imidazole ring system.A novel linear synthetic strategy using acyclic precursors was developed which enabled the addition of substituents in positions 1, 2, 4 and 5 of the imidazole ring unambiguously. A particular advantage of this route is that it would be possible to synthesise 4-substituted-5-hydroxyimidazoles.An interesting difference between the two synthetic routes is that nucleosides of the 5-hydroxyimidazoles were successfully synthesised using the linear synthetic strategy, however they could not be synthesised using the convergent strategy. This indicates the important role nucleophilicity could play in the intramolecular cyclisation step of the convergent synthetic strategy.The most important implications of the present study are the development of two separate, unambiguous synthetic routes to the 5-hydroxyimidazoles, employinginexpensive acyclic precursors. The routes could provide access to a variety of substituted 5-hydroxyimidazoles in order to build a library of these compounds.

Co-crystallising sugars by the supersaturation process was investigated using sucrose and lactose as the matrix sugars. The components to be cocrystallised with either sucrose or lactose were a variety of mono- and disaccharides along with sweeteners such as saccharin. Analysis of the materials yielded from the supersaturation process was done primarily by differential scanning Calorimetry (DSC) and powder x-ray diffraction (PXRD). DSC analysis allowed information to be obtained on the thermal behaviour of the various co-crystalline materials, whilst PXRD permitted information on the structural aspects of the materials to be gained. These two forms of analysis were complimentary to each other, each revealed unique characteristics of the co-crystalline materials. To unambiguously differentiate the difference between a material that is co-crystalline and one that is not, physical blends of the sugars to be cocrystallised were analysed by DSC and PXRD. This approach allowed for identification of all the components in the mixture, more importantly, this identification was achievable at all levels of the second component in the mixture. Co-crystallising either sucrose or lactose, with various sugars, yielded solely co-crystalline material up to a certain level of the added sugar. Once this level has been reached, two distinct phases appear in both DSC and PXRD analysis. A co-crystallised and a phase relating to the added sugar can be observed. The formation of a potentially co-crystalline material appears to result from a direct inclusion of the added sugar into the matrix sugar. DSC analysis of the co-crystallised material revealed thermal behaviour that is suggestive of a doping of the matrix sugar by the added component. PXRD analysis did provide some data to further this argument, axis elongation for co-crystallised material is suggestive of a sopping of the main phase. However, determination of the unit cell volumes did not yield conclusive evidence to help prove this hypothesis though. This behaviour in both forms of analysis was generally proportional to the quantity of the second component that has become included into the matrix sugar. The formation of solely co-crystalline materials appears to rely on the structural similarity between the matrix sugar and the component to be included. A higher degree of similarity is reflected by a high level of inclusion of the added component. Co-crystallisation appears to rely on a degree of intermolecular sugar-sugar recognition. The inclusion of a second component is not solely down to structural similarities between materials however. It appears that there are kinetic factors potentially involved to. Varying the method of co-crystallisation allowed for higher, or lower, amounts of various second components to be included within a matrix sugar. The appearance of co-crystalline materials may be due to the inclusion of the second component in an amorphous state. Analysis by Autosorb of various co-crystalline materials has dispelled this idea. All co-crystalline materials behaved in a manner that was indicative of a crystalline material. During the course of the work with sucrose, it was noted that a unique melting point was observed. From previous work, this unique phase was thought to be a hydrated form of sucrose. Further analysis on this material has allowed for further postulation on its formation and on new methods of its synthesis.

The area of liquid crystals has received a substantial research effort over the last century, particularly when the beneficial applications such as Liquid Crystal Displays (LCDs) were realised and developed. The changes to the molecular structure of liquid crystals can have a significant effect upon their mesomorphism and ferroelectric properties. Most of the research in liquid crystal for display applications concentrates on the design and synthesis of novel mesogenic cores to which straight terminal alkyl or alkoxy chains are attached. However, little is known about the effects upon the mesomorphism and ferroelectric properties of varying the terminal chains. The synthesis and mesomorphic properties of a systematic range of ortho difluoroterphenyls with a bulky terminal chain are detailed. The bulky terminal chain consists of either a tertiarybutyl group or a trimethylsilyl unit, each separated from the core by a short (dimethylene) chain, with the other terminal chain being either octyloxy or heptyl. Unusually for liquid crystals with bulky terminal chains, the smectic phase stability (particularly smectic C) is upheld by more than the nematic phase stability, and in most cases the smectic C phase stability is actually higher than comparable analogues with conventional unbranched terminal chains. It is postulated that the surprisingly high smectic C phase stability results from a phase separation effect due to the incompatibility of the spherical bulky group and the conventional unbranched terminal chain, hence implying that the smectic 'layers' are well defined, and such definition of the layers bodes well for bookshelf geometry in ferroelectric mixtures. Two mono- and four trifluoroterphenyls with a bulky terminal chain were prepared in this work to study the effect on the mesomorphic behaviour of varying the degree of fluoro substituents upon the multi-ring system. Two chiral ortho difluoro-substituted terphenyl compounds were prepared also in this work for future ferroelectric mixtures.

A thesis submitted to the Faculty of Education in fulfillment of the requirements for the Degree of Doctor of Education (Science Education) in the Department of Mathematics, Science and Technology Education at the University Of Zululand, South Africa, 2012. / This study sought to determine the conceptual difficulties experienced by grade 12 physical science learners with regard to mechanics. It also sought to identify the most prevalent alternative conceptions among grade 12 physical science learners in the area of mechanics, and develop interventions to alleviate the identified conceptual difficulties and alternative conceptions. In this regard, the study compared the effectiveness of a traditional lecture, outcomes-based education (OBE) and blended instructional approaches in alleviating or overcoming the identified conceptual difficulties and alternative conceptions concerning mechanics. The aspects of Mechanics dealt with in this study were: work and energy, motion on the inclined surfaces, projectile motion, force concept, static objects and Newton’s Third Law of Motion. In addressing the above research problem, the study developed and presented a theoretical and conceptual framework derived from the review of relevant literature, in line with the research questions of the study. The conceptual framework developed was based on the constructivist views of learning. A total of one hundred and forty (140) grade 12 physical science learners from Empangeni Education District were involved in this study. The study followed the quasi-experimental non-equivalent comparison-group research design. Though quantitative in design, the study also used qualitative research methods. Thus, both quantitative and qualitative data were collected. From the quantitative data, the findings showed highly statistically significant gains between pre- and post-test scores of OBE and blended approaches in particular. The average normalised gain score concept was also used determine the most effective instructional approach. Convenience sampling was used to select participating schools. A Test in Basic Mechanics (TBM) was designed to assess the learners’ understanding of the most basic concepts in mechanics. The TBM was administered both as a pre- and post-test to the three groups (traditional, OBE and blended groups) to determine the level of experience, knowledge, pre-existing alternative conceptions, level of understanding of basic concepts and principles on mechanics topics identified at the start of the investigation. As a pre-test, the TBM was also used to identify the specific conceptual difficulties and alternative conceptions in mechanics. The identification of the conceptual difficulties and alternative conceptions after the pre-test was followed by three instructional interventions (the traditional, OBE and the blended approach). The three interventions addressed the same mechanics topics mentioned above. These interventions were then followed by post-tests to ascertain the effectiveness of the interventions in addressing the identified conceptual difficulties and alternative conceptions, as well as any conceptual difficulties and alternative conceptions which were resistant to change even after the interventions. The results revealed that the learners experienced conceptual difficulties with regard to (a) resolving the components of the weight; (b) work concept; (c) work-energy theorem application; (d) kinetic energy concept; and (e) principle of conservation of mechanical energy application. Regarding the most prevalent alternative conceptions in mechanics, learners held eight alternative conceptions related to kinematical and dynamical concepts. Alternative conceptions held by the learners in mechanics concerned the following: (a) the acceleration and velocity of projectile motion; (b) weight/mass of an object as related to Newton’s Third Law of motion; (c) force concept; (d) objects in motion; (e) static objects; (f) Newton’s Third Law of motion; (g) acceleration of projectiles; and (h) active force. The average normalised gains for the traditional, OBE and blended instructional approaches were (g) = 0,20; (g) = 0,30; and (g) = 0,60, respectively. This confirmed the statistical analysis computed using One Way Analysis of Variance (ANOVA), that the blended instructional approach was the most effective instructional approach in alleviating the conceptual difficulties and alternative conceptions in mechanics. Qualitative data showed that most of the pre-existing conceptual difficulties and alternative conceptions appeared to have been alleviated, although not completely overcome by the interventions. There were statistically significant differences that were found among the traditional, OBE and blended instructional interventions. It is therefore noted that the blended instructional approach to teaching and learning can have a significant contribution to overcoming conceptual difficulties and alternative conceptions in mechanics, and the improvement of efficiency of learning. The study concluded that conceptual difficulties and alternative conceptions in mechanics could best be alleviated using the blended approach to teaching and learning. A number of recommendations were also made. Some alternative conceptions were resistant to change in the face of the traditional lecture based teaching. This meant that a more powerful teaching technique had to be devised. Thus, physical science educators should be encouraged to use the blended approach to teaching and learning in order to accommodate all learners in a class. Blended teaching and learning is mixing of different teaching and learning environments – mainly manifested in combining face-to-face instruction with the computer mediated-instruction. In one class of learners there are different learner characteristics. Learners learn in different ways like learning through lecture (telling), discussion, problem solving, practical work, discovering, experimenting, using pictures and diagrams, videos and demonstrations.

Thesis (Ed.M.)--Boston University

Thesis (Ed.M.)--Boston University / The organization of a unit of work for use in twelfth grade physiography is the problem of this study. It is hoped that the contents of the study would be adaptable for use in a program where instead of the conventional high school subjects in separate courses such as Chemistry, Physics, and Earth Science, all phases of science are organized in an integrated extensive course called Physical Science.

MSCEDU / Department of Curriculum Studies and Education Management

A dissertation submitted in fulfilment of the requirements for the Degree Master of Education in the Department of Curriculum and Instructional Studies, Faculty of Education at the University Of Zululand, 2018. / Physical Sciences continue to be one of the subjects that yield poor results in Grade 12 every year. Many factors have been said to contribute to the poor Grade 12 results including resources and teaching methods. This study however, investigated the educators’ and learners’ views on factors that contribute to poor performance in Grade 12 from a rural UMkhanyakude district of KwaZulu Natal. A questionnaire with both closed and open-ended questions was used to determine learners’ views, while an interview schedule was used to delve into the educators’ views. Frequency results from learner questionnaires revealed that learners viewed issues such as overcrowded classrooms, lack of parental support, lack of support from education local office, lack of resources, and a negative attitude towards Physical Science as the main factors that contribute to poor performance in Grade 12 Physical Sciences. The inductive analysis of the teachers’ interview transcripts revealed that teachers believed that giving extra support without resources such as well-resourced laboratories, and parental support is sometimes impossible. These key findings can contribute to programmes that seek to strengthen the teaching of Sciences in rural contexts; thus this study makes a contribution to what is known about the factors that contribute to poor performance in Grade 12 in a rural context.