An intervention on how using easily accessible resources to carry out hands-on practical activities in science influences science teachers’ conceptual development and dispositions
- Authors: Asheela, Eva Ndagwedha
- Date: 2017
- Subjects: Science teachers -- In-service training -- Namibia , Science teachers -- Namibia -- Case studies , Science -- Study and teaching -- Activity programs -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/8330 , vital:21385
- Description: The reform and transformation of education systems in terms of enhancing Science, Technology Engineering and Mathematics (STEM) education in the schooling systems is gaining momentum in different parts of the world. It is argued that there is a need to enhance science education, particularly in Africa, because science education is considered to be the main vehicle through which the greater objectives such as national development and improvement in the quality of life can be realised. Namibia as a country is no exception. A key way through which science education can be enhanced is through carrying out practical activities during teaching and learning. Despite the crucial role that practical activities play in science subjects, it appears that they are not carried out in most of the Namibian science classrooms. It is against this background that this study explored an intervention on how easily accessible resources to carry out hands-on practical activities in science, influenced science teachers’ conceptual development and dispositions towards the use of practical activities in science. In this study, a mixed methods case study approach underpinned by an interpretive paradigm was adopted. The research was conducted with 21 in-service science teachers from schools in Namibia who were all on a two year part-time BEd (Honours) program delivered in Namibia by a South African university from the Eastern Cape. To generate data, document analysis, questionnaires, semi-structured interviews, an intervention in the form of workshops on practical activities, lesson observations, which were videotaped, as well as teacher reflections were used. Conceptual development, disposition and professional development served as the conceptual lenses. Vygotsky’s sociocultural theory in conjunction with Shulman’s pedagogical content knowledge (PCK) were the theoretical frameworks adopted in the study.The findings showed that there was a general perception among the participants before the intervention that in order to carry out practical activities, well-equipped laboratories, conventional chemicals and equipment are needed. Some teachers had never used practical activities in their science classes with a range of constraints or hindrances provided as reasons. The findings additionally showed that for teachers to use easily accessible resources to carry out practical activities in their science classrooms, they need the knowledge and exposure on how to use these resources. The findings thus showed that this professional development approach raised motivation, knowledge and the skills of the science teacher participants to include practical activities in their science lessons using easily accessible resources. A recommendation is that if teachers are given opportunities, through professional development platforms to engage in hands- on practical activities using easily accessible resources, they can be enabled and motivated to implement these in their science classrooms.
- Full Text:
- Date Issued: 2017
- Authors: Asheela, Eva Ndagwedha
- Date: 2017
- Subjects: Science teachers -- In-service training -- Namibia , Science teachers -- Namibia -- Case studies , Science -- Study and teaching -- Activity programs -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/8330 , vital:21385
- Description: The reform and transformation of education systems in terms of enhancing Science, Technology Engineering and Mathematics (STEM) education in the schooling systems is gaining momentum in different parts of the world. It is argued that there is a need to enhance science education, particularly in Africa, because science education is considered to be the main vehicle through which the greater objectives such as national development and improvement in the quality of life can be realised. Namibia as a country is no exception. A key way through which science education can be enhanced is through carrying out practical activities during teaching and learning. Despite the crucial role that practical activities play in science subjects, it appears that they are not carried out in most of the Namibian science classrooms. It is against this background that this study explored an intervention on how easily accessible resources to carry out hands-on practical activities in science, influenced science teachers’ conceptual development and dispositions towards the use of practical activities in science. In this study, a mixed methods case study approach underpinned by an interpretive paradigm was adopted. The research was conducted with 21 in-service science teachers from schools in Namibia who were all on a two year part-time BEd (Honours) program delivered in Namibia by a South African university from the Eastern Cape. To generate data, document analysis, questionnaires, semi-structured interviews, an intervention in the form of workshops on practical activities, lesson observations, which were videotaped, as well as teacher reflections were used. Conceptual development, disposition and professional development served as the conceptual lenses. Vygotsky’s sociocultural theory in conjunction with Shulman’s pedagogical content knowledge (PCK) were the theoretical frameworks adopted in the study.The findings showed that there was a general perception among the participants before the intervention that in order to carry out practical activities, well-equipped laboratories, conventional chemicals and equipment are needed. Some teachers had never used practical activities in their science classes with a range of constraints or hindrances provided as reasons. The findings additionally showed that for teachers to use easily accessible resources to carry out practical activities in their science classrooms, they need the knowledge and exposure on how to use these resources. The findings thus showed that this professional development approach raised motivation, knowledge and the skills of the science teacher participants to include practical activities in their science lessons using easily accessible resources. A recommendation is that if teachers are given opportunities, through professional development platforms to engage in hands- on practical activities using easily accessible resources, they can be enabled and motivated to implement these in their science classrooms.
- Full Text:
- Date Issued: 2017
Nonlinear optical responses of phthalocyanines in the presence of nanomaterials or when embedded in polymeric materials
- Authors: Bankole, Owolabi Mutolib
- Date: 2017
- Subjects: Phthalocyanines , Phthalocyanines -- Optical properties , Alkynes , Triazoles , Nonlinear optics , Photochemistry , Complex compounds , Amines , Mercaptopyridine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/45794 , vital:25548
- Description: This work describes the synthesis, photophysical and nonlinear optical characterizations of alkynyl Pcs (1, 2, 3, 8 and 9), 1,2,3-triazole ZnPc (4), mercaptopyridine Pcs (5, 6 and 7) and amino Pcs (10 and 11). Complexes 1, 2, 4, 7, 8, 9 and 11 were newly synthesized and characterized using techniques including 1H-NMR, MALDI-TOF, UV-visible spectrophotometry, FTIR and elemental analysis. The results of the characterizations were in good agreement with their molecular structures, and confirmed the purity of the new molecules. Complex 10 was covalently linked to pristine graphene (GQDs), nitrogen- doped (NGQDs), and sulfur-nitrogen co-doped (SNGQDs) graphene quantum dots; gold nanoparticles (AuNPs); poly(acrylic acid) (PAA); Fe3O4@Ag core-shell and Fe3O4- Ag hybrid nanoparticles via covalent bonding. Complex 11 was linked to Agx Auy alloy nanoparticles via NH2-Au and/or Au-S bonding, 2 and 3 were linked to gold nanoparticles (AuNPs) via clicked reactions. Evidence of successful conjugation of 2, 3, 10 and 11 to nanomaterials was revealed within the UV-vis, EDS, TEM, XRD and XPS spectra. Optical limiting (OL) responses of the samples were evaluated using open aperture Z-scan technique at 532 nm and 10 ns radiation in solution or when embedded in polymer mixtures. The analyses of the Z-scan data for the studied samples did fit to a two-photon absorption mechanism (2PA), but the Pcs and Pc-nanomaterial or polymer composites also possess the multi-photon absorption mechanisms aided by the triplet-triplet population to have reverse saturable absorption (RSA) occur. Phthalocyanines doped in polymer matrices showed larger nonlinear absorption coefficients (ßeff), third-order susceptibility (Im [x(3)]) and second-order hyperpolarizability (y), with an accompanying low intensity threshold (Ium) than in solution. Aggregation in DMSO negatively affected NLO behaviour of Pcs (8 as a case study) at low laser power, and improved at relatively higher laser power. Heavy atom-substituted Pcs (6) enhanced NLO and OL properties than lighter atoms such as 5 and 7. Direct relationship between enhanced photophysical properties and nonlinear effects favoured by excited triplet absorption of the 2, 3, 10 and 11 in presence of nanomaterials was established. Major factor responsible for the enhanced nonlinearities of 10 in the presence of NGQDs and SNGQDs were fully described and attributed to the surface defects caused by the presence of heteroatoms such as nitrogen and sulfur. The studies showed that phthalocyanines-nanomaterial composites were useful in applications such as optical switching, pulse compressor and laser pulse narrowing.
- Full Text:
- Date Issued: 2017
- Authors: Bankole, Owolabi Mutolib
- Date: 2017
- Subjects: Phthalocyanines , Phthalocyanines -- Optical properties , Alkynes , Triazoles , Nonlinear optics , Photochemistry , Complex compounds , Amines , Mercaptopyridine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/45794 , vital:25548
- Description: This work describes the synthesis, photophysical and nonlinear optical characterizations of alkynyl Pcs (1, 2, 3, 8 and 9), 1,2,3-triazole ZnPc (4), mercaptopyridine Pcs (5, 6 and 7) and amino Pcs (10 and 11). Complexes 1, 2, 4, 7, 8, 9 and 11 were newly synthesized and characterized using techniques including 1H-NMR, MALDI-TOF, UV-visible spectrophotometry, FTIR and elemental analysis. The results of the characterizations were in good agreement with their molecular structures, and confirmed the purity of the new molecules. Complex 10 was covalently linked to pristine graphene (GQDs), nitrogen- doped (NGQDs), and sulfur-nitrogen co-doped (SNGQDs) graphene quantum dots; gold nanoparticles (AuNPs); poly(acrylic acid) (PAA); Fe3O4@Ag core-shell and Fe3O4- Ag hybrid nanoparticles via covalent bonding. Complex 11 was linked to Agx Auy alloy nanoparticles via NH2-Au and/or Au-S bonding, 2 and 3 were linked to gold nanoparticles (AuNPs) via clicked reactions. Evidence of successful conjugation of 2, 3, 10 and 11 to nanomaterials was revealed within the UV-vis, EDS, TEM, XRD and XPS spectra. Optical limiting (OL) responses of the samples were evaluated using open aperture Z-scan technique at 532 nm and 10 ns radiation in solution or when embedded in polymer mixtures. The analyses of the Z-scan data for the studied samples did fit to a two-photon absorption mechanism (2PA), but the Pcs and Pc-nanomaterial or polymer composites also possess the multi-photon absorption mechanisms aided by the triplet-triplet population to have reverse saturable absorption (RSA) occur. Phthalocyanines doped in polymer matrices showed larger nonlinear absorption coefficients (ßeff), third-order susceptibility (Im [x(3)]) and second-order hyperpolarizability (y), with an accompanying low intensity threshold (Ium) than in solution. Aggregation in DMSO negatively affected NLO behaviour of Pcs (8 as a case study) at low laser power, and improved at relatively higher laser power. Heavy atom-substituted Pcs (6) enhanced NLO and OL properties than lighter atoms such as 5 and 7. Direct relationship between enhanced photophysical properties and nonlinear effects favoured by excited triplet absorption of the 2, 3, 10 and 11 in presence of nanomaterials was established. Major factor responsible for the enhanced nonlinearities of 10 in the presence of NGQDs and SNGQDs were fully described and attributed to the surface defects caused by the presence of heteroatoms such as nitrogen and sulfur. The studies showed that phthalocyanines-nanomaterial composites were useful in applications such as optical switching, pulse compressor and laser pulse narrowing.
- Full Text:
- Date Issued: 2017
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