A lean production approach to materials management in the Nigerian construction industry
- Authors: Albert, Idowu
- Date: 2020
- Subjects: Materials management , Lean manufacturing Construction industry -- Nigeria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/46008 , vital:39408
- Description: The Nigerian Construction Industry faces a problem of poor materials management that leads to, among other things, materials waste, poor quality of work, poor materials flow, project delay and cost overrun. Overcoming these challenges, requires the rethinking the current modus operandi of the Nigerian construction industry. One such method that has been espoused as having potential to improve materials management, and associated challenges is ‘lean production’. This research aimed at deciphering the lean approach to production management with a view of extracting its utility in enhancing materials management in the construction industry. The qualitative method of research inquiry that is rooted in the phenomenological paradigm was employed. The research activities included a comprehensive review of the related literature and study of selected cases. Abuja, the Federal capital territory of Nigeria was the selected geographical scope of the research. Ten case studies were purposefully selected for the study. The research instrument was a tick box used for direct observation. The study revealed that poor materials management has a negative effect on the materials management plan. Moreover, mixing of waste at the site, negates the effort for identification of materials waste streams, and makes it difficult to account for materials waste, as well as implementing a materials waste management policy on sites. The research also found that poor materials management has a significant effect (high, moderate or low) on materials waste, quality of work, materials flow, productivity, project delay, project profitability and accounting for materials. The research has developed a conceptual model for a lean production approach to materials management based on the results and informed by the theoretical framework. The study has achieved its aim of establishing an understanding of the lean production approach to materials management in the Nigerian construction industry. The study recommends that construction professionals should be well informed on the effects of poor materials management.
- Full Text:
- Date Issued: 2020
- Authors: Albert, Idowu
- Date: 2020
- Subjects: Materials management , Lean manufacturing Construction industry -- Nigeria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/46008 , vital:39408
- Description: The Nigerian Construction Industry faces a problem of poor materials management that leads to, among other things, materials waste, poor quality of work, poor materials flow, project delay and cost overrun. Overcoming these challenges, requires the rethinking the current modus operandi of the Nigerian construction industry. One such method that has been espoused as having potential to improve materials management, and associated challenges is ‘lean production’. This research aimed at deciphering the lean approach to production management with a view of extracting its utility in enhancing materials management in the construction industry. The qualitative method of research inquiry that is rooted in the phenomenological paradigm was employed. The research activities included a comprehensive review of the related literature and study of selected cases. Abuja, the Federal capital territory of Nigeria was the selected geographical scope of the research. Ten case studies were purposefully selected for the study. The research instrument was a tick box used for direct observation. The study revealed that poor materials management has a negative effect on the materials management plan. Moreover, mixing of waste at the site, negates the effort for identification of materials waste streams, and makes it difficult to account for materials waste, as well as implementing a materials waste management policy on sites. The research also found that poor materials management has a significant effect (high, moderate or low) on materials waste, quality of work, materials flow, productivity, project delay, project profitability and accounting for materials. The research has developed a conceptual model for a lean production approach to materials management based on the results and informed by the theoretical framework. The study has achieved its aim of establishing an understanding of the lean production approach to materials management in the Nigerian construction industry. The study recommends that construction professionals should be well informed on the effects of poor materials management.
- Full Text:
- Date Issued: 2020
The use of learning support materials in rural schools of Maputaland, KwaZulu-Natal, South Africa
- Authors: van der Merwe, Michelle
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386888 , vital:68186 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122865"
- Description: The African Coelacanth Ecosystem Programme (ACEP) was established in 2002 after the discovery of a colony of coelacanths off the Maputaland coast at Sodwana Bay, KwaZulu-Natal. The environmental education and awareness sub-programme developed learning support materials for use in schools and the materials were disseminated annually through teacher education workshops. This study aimed to uncover the use of these learning support materials in the rural schools of Maputaland. The active learning framework, originally proposed and developed by O’Donoghue (2001), was used to analyse the materials. Collectively, the ACEP materials cover a range of active learning aspects; however alignment with the curriculum has resulted in an increased focus on experiments, accompanied by a loss of environmental content and a narrowing scope for active environmental learning. Workshop questionnaires and four school case studies revealed the patterns of practice of use of materials in schools. The stated use of materials by teachers is not fully realised in the actual classroom practice which centres on learning content and concept definitions. There is no culture of use of materials in the schools following the annual introduction of ACEP materials. It was also found that the marine and coastal knowledge holding power is outside the realm of the teachers’ practice and control. The findings of this study come at a time when there is uncertainty over the future of South African education and the curriculum. This research may inform the environmental education and coastal and marine education field as to their role in education and more specifically the development of learning support materials.
- Full Text:
- Date Issued: 2010
- Authors: van der Merwe, Michelle
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386888 , vital:68186 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122865"
- Description: The African Coelacanth Ecosystem Programme (ACEP) was established in 2002 after the discovery of a colony of coelacanths off the Maputaland coast at Sodwana Bay, KwaZulu-Natal. The environmental education and awareness sub-programme developed learning support materials for use in schools and the materials were disseminated annually through teacher education workshops. This study aimed to uncover the use of these learning support materials in the rural schools of Maputaland. The active learning framework, originally proposed and developed by O’Donoghue (2001), was used to analyse the materials. Collectively, the ACEP materials cover a range of active learning aspects; however alignment with the curriculum has resulted in an increased focus on experiments, accompanied by a loss of environmental content and a narrowing scope for active environmental learning. Workshop questionnaires and four school case studies revealed the patterns of practice of use of materials in schools. The stated use of materials by teachers is not fully realised in the actual classroom practice which centres on learning content and concept definitions. There is no culture of use of materials in the schools following the annual introduction of ACEP materials. It was also found that the marine and coastal knowledge holding power is outside the realm of the teachers’ practice and control. The findings of this study come at a time when there is uncertainty over the future of South African education and the curriculum. This research may inform the environmental education and coastal and marine education field as to their role in education and more specifically the development of learning support materials.
- Full Text:
- Date Issued: 2010
Synthesis of ytterbium bisphthalocyanines
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189887 , vital:44943 , xlink:href="https://doi.org/10.1016/j.optmat.2014.05.013"
- Description: Herein we report on the syntheses, photophysico-chemical properties and nonlinear absorption parameters of bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-2-yloxy phthalocyaninato)} ytterbium (III) (3) and bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). The fluorescence and singlet oxygen quantum yields obtained for complexes 3 and 4 are low. The triplet quantum yield obtained for complex 3 is high at ΦT = 0.89 whereas for complex 4 ΦT = 0.48. The third order optical susceptibility values are of the order: 10−11 esu (for complex 3), and 10−13 esu (for complex 4) while the hyperpolarizability values are of the order: 10−28 esu (for complex 3) and 10−31 esu (for complex 4). Complexes 3 and 4 show two-photon absorption coefficients of the order of 10−46 cm4 s/photon and 10−48 cm4 s/photon, and threshold intensities as low as 0.3 J cm−2 and 0.0045 J cm−2, respectively.
- Full Text:
- Date Issued: 2014
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189887 , vital:44943 , xlink:href="https://doi.org/10.1016/j.optmat.2014.05.013"
- Description: Herein we report on the syntheses, photophysico-chemical properties and nonlinear absorption parameters of bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-2-yloxy phthalocyaninato)} ytterbium (III) (3) and bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). The fluorescence and singlet oxygen quantum yields obtained for complexes 3 and 4 are low. The triplet quantum yield obtained for complex 3 is high at ΦT = 0.89 whereas for complex 4 ΦT = 0.48. The third order optical susceptibility values are of the order: 10−11 esu (for complex 3), and 10−13 esu (for complex 4) while the hyperpolarizability values are of the order: 10−28 esu (for complex 3) and 10−31 esu (for complex 4). Complexes 3 and 4 show two-photon absorption coefficients of the order of 10−46 cm4 s/photon and 10−48 cm4 s/photon, and threshold intensities as low as 0.3 J cm−2 and 0.0045 J cm−2, respectively.
- Full Text:
- Date Issued: 2014
Cryptosepalum exfoliatum subsp. pseudotaxus
- Pocock, Mary Agard, Dold, Tony
- Authors: Pocock, Mary Agard , Dold, Tony
- Date: 1925-06-22 , 2016-05-13
- Subjects: Cryptosepalum exfoliatum , Fabaceae , Cryptosepalum , Cryptosepalum exfoliatum De Wild. subsp. pseudotaxus (Baker f.) P.A. Duvign. & Brenan
- Language: English
- Type: image , specimen , still image , herbarium specimen
- Identifier: http://hdl.handle.net/10962/178164 , vital:42917 , M. A. Pocock 6778 , Selmar Schonland Herbarium (GRA)
- Description: Image of original plant specimen held at Selmar Schonland Herbarium, Albany Museum/Rhodes University: M. A. Pocock 6778. Label: Cryptosepalum Pseudotaxus Bak.f = C. exfoliatum De Wild. Location: Kutsi : alt. 4200' : bark used for tying. Legit M.A. Pocock Date 22 June 1925 , Mary Agard Pocock Diary entry: June 22. [1925] : 'Found the bark tree (bark used for tying) in bloom ... got plenty of the curious little, very sweet-scented blooms.' Quoted from 'Bushmen, Botany and Baking Bread. Compiled and edited by Tony Dold and Jean Kelly (2018). , Vernacular plant names: Mbundu - Mukuvi, Mukuve. Bushman - Koviku , Trust: Mary Agard Pocock , Forms part of: Mary Agard Pocock collections
- Full Text: false
- Date Issued: 1925-06-22
- Authors: Pocock, Mary Agard , Dold, Tony
- Date: 1925-06-22 , 2016-05-13
- Subjects: Cryptosepalum exfoliatum , Fabaceae , Cryptosepalum , Cryptosepalum exfoliatum De Wild. subsp. pseudotaxus (Baker f.) P.A. Duvign. & Brenan
- Language: English
- Type: image , specimen , still image , herbarium specimen
- Identifier: http://hdl.handle.net/10962/178164 , vital:42917 , M. A. Pocock 6778 , Selmar Schonland Herbarium (GRA)
- Description: Image of original plant specimen held at Selmar Schonland Herbarium, Albany Museum/Rhodes University: M. A. Pocock 6778. Label: Cryptosepalum Pseudotaxus Bak.f = C. exfoliatum De Wild. Location: Kutsi : alt. 4200' : bark used for tying. Legit M.A. Pocock Date 22 June 1925 , Mary Agard Pocock Diary entry: June 22. [1925] : 'Found the bark tree (bark used for tying) in bloom ... got plenty of the curious little, very sweet-scented blooms.' Quoted from 'Bushmen, Botany and Baking Bread. Compiled and edited by Tony Dold and Jean Kelly (2018). , Vernacular plant names: Mbundu - Mukuvi, Mukuve. Bushman - Koviku , Trust: Mary Agard Pocock , Forms part of: Mary Agard Pocock collections
- Full Text: false
- Date Issued: 1925-06-22
Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains
- Britton, Jonathan, Martynov, Alexander G, Oluwole, David O, Gorbunova, Yulia G, Tsivadze, Yulia G, Nyokong, Tebello
- Authors: Britton, Jonathan , Martynov, Alexander G , Oluwole, David O , Gorbunova, Yulia G , Tsivadze, Yulia G , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239812 , vital:50769 , xlink:href="https://doi.org/10.1142/S1088424616501042"
- Description: This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-nn-butoxyphthalocyanine 1H22 and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H22 in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[χ(3)χ(3)]/αα, βeffβeff, and γγ for 1H22in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[χ(3)χ(3)]/αα values of the order of 10−11−11 in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H22 were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[χ(3)χ(3)]/αα was almost three times higher in comparison with 1H22 solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation
- Full Text:
- Date Issued: 2016
- Authors: Britton, Jonathan , Martynov, Alexander G , Oluwole, David O , Gorbunova, Yulia G , Tsivadze, Yulia G , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239812 , vital:50769 , xlink:href="https://doi.org/10.1142/S1088424616501042"
- Description: This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-nn-butoxyphthalocyanine 1H22 and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H22 in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[χ(3)χ(3)]/αα, βeffβeff, and γγ for 1H22in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[χ(3)χ(3)]/αα values of the order of 10−11−11 in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H22 were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[χ(3)χ(3)]/αα was almost three times higher in comparison with 1H22 solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation
- Full Text:
- Date Issued: 2016
Emerging patterns of abstraction in environmental education: A review of materials, methods and professional development perspectives
- O'Donoghue, Rob B, Russo, Vladimir
- Authors: O'Donoghue, Rob B , Russo, Vladimir
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373610 , vital:66707 , xlink:href="https://doi.org/10.1080/1350462042000258170"
- Description: The epistemic unconscious is the history of the field. And it is clear that, to secure some chance of really knowing what one is doing, one has to unfold what is inscribed in the various relations of implication in which the thinker and his thoughts are caught up, that is, the presuppositions he engages and the inclusions and exclusions he unwittingly performs. (Bourdieu, 2000, p. 99).
- Full Text:
- Date Issued: 2004
- Authors: O'Donoghue, Rob B , Russo, Vladimir
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373610 , vital:66707 , xlink:href="https://doi.org/10.1080/1350462042000258170"
- Description: The epistemic unconscious is the history of the field. And it is clear that, to secure some chance of really knowing what one is doing, one has to unfold what is inscribed in the various relations of implication in which the thinker and his thoughts are caught up, that is, the presuppositions he engages and the inclusions and exclusions he unwittingly performs. (Bourdieu, 2000, p. 99).
- Full Text:
- Date Issued: 2004
A resource-based learning approach to professional development: the case of the ACEE (Rhodes University Advanced Certificate in Environmental Education)
- Agria Russo, Vladimir Kiluange
- Authors: Agria Russo, Vladimir Kiluange
- Date: 2004
- Subjects: Rhodes University Advanced Certificate in Environmental Education Teaching -- Aids and devices -- South Africa Environmental education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1741 , http://hdl.handle.net/10962/d1003625
- Description: This interpretative case study derives and examines the characterising features of the resource-based learning approach used in the Rhodes University Advanced Certificate in Environmental Education (ACEE), particularly in Module 1 (Environment and Environmental Issues) and Module 3 (Contemporary Environmental Issues). The study explores processes of resource-based learning through the analysis of three individual case stories of participants’ experience in adaptive use of learning support materials in different work contexts. It discusses the relationship between thematic categories related to participants’ experience of assignment work, and course design and course implementation. This study indicates that resource-based learning processes in the ACEE involve curriculum deliberation and the use of resource packs in supporting participants’ practice. It also indicates that the ACEE’s practice-based orientation to workplace-based assignments plays an important role in supporting the adaptive use of learning support materials, encouraging lifelong learning and developing applied competence. It highlights the significance of reflexive narration of practice in improving course participants’ educational practice. A diagrammatic representation of the unfolding and intermeshed characterising features of resource-based learning is presented. The study argues that resource-based learning in the ACEE appears to create possibilities for the course participants to become scaffolders and co-constructors of their own learning. It notes that resource-based learning can enable course participants to take ownership of their educational and workplace needs, and to develop skills and competences necessary to respond to environmental issues and risks in southern Africa. This study examines the potential that the reflexive narration of practice has in supporting course participants to engage in better ways of doing things in their workplace-based contexts. This study provides some recommendations to enhance the Advanced Certificate in Environmental Education as well as some ‘fuzzy generalisations’ that might guide the Southern African Development Community (SADC) Regional Environmental Education Programme (REEP) in the development and adaptation of professional development courses in southern Africa.
- Full Text:
- Date Issued: 2004
- Authors: Agria Russo, Vladimir Kiluange
- Date: 2004
- Subjects: Rhodes University Advanced Certificate in Environmental Education Teaching -- Aids and devices -- South Africa Environmental education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1741 , http://hdl.handle.net/10962/d1003625
- Description: This interpretative case study derives and examines the characterising features of the resource-based learning approach used in the Rhodes University Advanced Certificate in Environmental Education (ACEE), particularly in Module 1 (Environment and Environmental Issues) and Module 3 (Contemporary Environmental Issues). The study explores processes of resource-based learning through the analysis of three individual case stories of participants’ experience in adaptive use of learning support materials in different work contexts. It discusses the relationship between thematic categories related to participants’ experience of assignment work, and course design and course implementation. This study indicates that resource-based learning processes in the ACEE involve curriculum deliberation and the use of resource packs in supporting participants’ practice. It also indicates that the ACEE’s practice-based orientation to workplace-based assignments plays an important role in supporting the adaptive use of learning support materials, encouraging lifelong learning and developing applied competence. It highlights the significance of reflexive narration of practice in improving course participants’ educational practice. A diagrammatic representation of the unfolding and intermeshed characterising features of resource-based learning is presented. The study argues that resource-based learning in the ACEE appears to create possibilities for the course participants to become scaffolders and co-constructors of their own learning. It notes that resource-based learning can enable course participants to take ownership of their educational and workplace needs, and to develop skills and competences necessary to respond to environmental issues and risks in southern Africa. This study examines the potential that the reflexive narration of practice has in supporting course participants to engage in better ways of doing things in their workplace-based contexts. This study provides some recommendations to enhance the Advanced Certificate in Environmental Education as well as some ‘fuzzy generalisations’ that might guide the Southern African Development Community (SADC) Regional Environmental Education Programme (REEP) in the development and adaptation of professional development courses in southern Africa.
- Full Text:
- Date Issued: 2004
The use of learning support materials in the rural schools of Maputaland, Kwa-Zulu Natal
- Authors: Van der Merwe, Michelle
- Date: 2011
- Subjects: Environmental education -- South Africa -- Maputaland African Coelacanth Ecosystem Programme Coelacanthiformes -- South Africa -- Maputaland Teaching -- Aids and devices -- South Africa -- Maputaland Environmental education -- Curricula -- South Africa -- Maputaland
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1815 , http://hdl.handle.net/10962/d1003701
- Description: The African Coelacanth Ecosystem Programme (ACEP) was established in 2002 after the discovery of a colony of coelacanths off the Maputaland coast at Sodwana Bay, KwaZulu Natal. The environmental education and awareness sub-programme developed learning support materials (LSM's) for use in schools and the materials were disseminated annually through teacher education workshops. This study aimed to uncover the use of these LSM's in the rural schools of Maputaland. The active learning framework was used to analyse the materials. Collectively, the ACEP materials cover a range of active learning aspects; however alignment with the curriculum has resulted in an increased focus on experiments, accompanied by a loss of environmental content and a narrowing scope for active environmental learning. Workshop questionnaires and four school case studies revealed the patterns of practice of use of materials in schools. The stated use of materials by teachers is not fully realized in the actual classroom practice which centres on learning content and concept definitions. There is no culture of use of materials in the schools following the annual introduction of ACEP materials. It was also found that the marine and coastal knowledge holding power is outside the realm of the teachers' practice and control. The findings of this study come at a time when there is uncertainty over the future of South African education and the curriculum. This research may inform the environmental education and coastal and marine education field as to their role in education and more specifically the development of learning support materials.
- Full Text:
- Date Issued: 2011
- Authors: Van der Merwe, Michelle
- Date: 2011
- Subjects: Environmental education -- South Africa -- Maputaland African Coelacanth Ecosystem Programme Coelacanthiformes -- South Africa -- Maputaland Teaching -- Aids and devices -- South Africa -- Maputaland Environmental education -- Curricula -- South Africa -- Maputaland
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1815 , http://hdl.handle.net/10962/d1003701
- Description: The African Coelacanth Ecosystem Programme (ACEP) was established in 2002 after the discovery of a colony of coelacanths off the Maputaland coast at Sodwana Bay, KwaZulu Natal. The environmental education and awareness sub-programme developed learning support materials (LSM's) for use in schools and the materials were disseminated annually through teacher education workshops. This study aimed to uncover the use of these LSM's in the rural schools of Maputaland. The active learning framework was used to analyse the materials. Collectively, the ACEP materials cover a range of active learning aspects; however alignment with the curriculum has resulted in an increased focus on experiments, accompanied by a loss of environmental content and a narrowing scope for active environmental learning. Workshop questionnaires and four school case studies revealed the patterns of practice of use of materials in schools. The stated use of materials by teachers is not fully realized in the actual classroom practice which centres on learning content and concept definitions. There is no culture of use of materials in the schools following the annual introduction of ACEP materials. It was also found that the marine and coastal knowledge holding power is outside the realm of the teachers' practice and control. The findings of this study come at a time when there is uncertainty over the future of South African education and the curriculum. This research may inform the environmental education and coastal and marine education field as to their role in education and more specifically the development of learning support materials.
- Full Text:
- Date Issued: 2011
Unsustainable trade-offs: provisioning ecosystem services in rapidly changing Likangala River catchment in southern Malawi
- Pullanikkatil, Deepa, Mograbi, Penelope J, Palamuleni, Lobina, Ruhiiga, Tabukeli, Shackleton, Charlie M
- Authors: Pullanikkatil, Deepa , Mograbi, Penelope J , Palamuleni, Lobina , Ruhiiga, Tabukeli , Shackleton, Charlie M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/176308 , vital:42683 , https://doi.org/10.1007/s10668-018-0240-x
- Description: Provisioning ecosystem services of the Likangala River Catchment in southern Malawi are important for livelihoods of those living there. Remote sensing, participatory mapping and focus group discussions were used to explore the spatio-temporal changes and trade-ofs in land-cover change from 1984 to 2013, and how that afects provisioning ecosystem services in the area. Communities derive a number of provisioning ecosystem services from the catchment. Forty-eight species of edible wild animals (including birds), 28 species of edible wild plants and fungi, 22 species of medicinal plants, construction materials, ornamental fowers, frewood, honey, gum, reeds and thatch/weaving grasses were derived from the catchment and used by local communities.
- Full Text:
- Date Issued: 2020
- Authors: Pullanikkatil, Deepa , Mograbi, Penelope J , Palamuleni, Lobina , Ruhiiga, Tabukeli , Shackleton, Charlie M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/176308 , vital:42683 , https://doi.org/10.1007/s10668-018-0240-x
- Description: Provisioning ecosystem services of the Likangala River Catchment in southern Malawi are important for livelihoods of those living there. Remote sensing, participatory mapping and focus group discussions were used to explore the spatio-temporal changes and trade-ofs in land-cover change from 1984 to 2013, and how that afects provisioning ecosystem services in the area. Communities derive a number of provisioning ecosystem services from the catchment. Forty-eight species of edible wild animals (including birds), 28 species of edible wild plants and fungi, 22 species of medicinal plants, construction materials, ornamental fowers, frewood, honey, gum, reeds and thatch/weaving grasses were derived from the catchment and used by local communities.
- Full Text:
- Date Issued: 2020
The nonlinear absorption in new lanthanide double decker pyridine-based phthalocyanines in solution and thin films
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189307 , vital:44836 , xlink:href="https://doi.org/10.1016/j.optmat.2015.05.022"
- Description: The optical behavior of bis-{2(3), 9(10), 16(17), 23(24)-(tetrapyridin-4-yloxy phthalocyaninato)} lanthanum (III) (2) and its ytterbium (3) counterpart in dimethyl sulfoxide are presented and compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). We report on the third-order susceptibility, second-order hyperpolarizability and the limiting threshold values. The nonlinear optical limiting threshold values of complexes 2, 3 and 4 showed improvement in the solid state (thin films), with complex 4 giving the best value at 0.033 J cm−2.
- Full Text:
- Date Issued: 2015
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189307 , vital:44836 , xlink:href="https://doi.org/10.1016/j.optmat.2015.05.022"
- Description: The optical behavior of bis-{2(3), 9(10), 16(17), 23(24)-(tetrapyridin-4-yloxy phthalocyaninato)} lanthanum (III) (2) and its ytterbium (3) counterpart in dimethyl sulfoxide are presented and compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). We report on the third-order susceptibility, second-order hyperpolarizability and the limiting threshold values. The nonlinear optical limiting threshold values of complexes 2, 3 and 4 showed improvement in the solid state (thin films), with complex 4 giving the best value at 0.033 J cm−2.
- Full Text:
- Date Issued: 2015
Constructability effects of green buildings
- Authors: Hurbissoon, Roneesh Mehta
- Date: 2011
- Subjects: Sustainable construction , Architecture and energy conservation , Construction industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9722 , http://hdl.handle.net/10948/1379 , Sustainable construction , Architecture and energy conservation , Construction industry
- Description: The Earth's health is deteriorating and will deteriorate even more rapidly unless people adopt eco-friendly policies. Green building has long been a concept but it has not yet been universally applied in practice. The concept of sustainability emerged in the 1970s and can be associated with the energy crisis and environmental pollution concerns. This research is aimed at investigating whether building “green” is more demanding than non-green buildings in terms of cost and the use of green materials against traditional materials; whether professionals in the construction industry are knowledgeable in terms of green buildings; and lastly, to determine whether green buildings are contributing significantly to the environment. The literature reviewed and results of quantitative research amongst professionals from the Island of Mauritius formed the basis of the study. The study revealed that green building is expensive relative to traditional buildings considering. However, the concepts employed (for example: lower energy use, less waste disposal, lower water usage, and sustainable design) provide green buildings with long term savings. Furthermore, the scarcity of natural materials makes it expensive. The study also showed that contractors and professionals have a preference for traditional materials over green materials thus making them more familiar with traditional materials. Contractors and professionals are believed to understand green materials only on a limited basis. This may be attributed to the specific environmental issues involved; however, the research revealed that the professionals are familiar with the basic concepts of green buildings. Lastly, the research showed that green building is still at its infancy but the benefits of green buildings are understood; resulting in green buildings having a good growth potential. The study should be valuable to construction industry professional and clients.
- Full Text:
- Date Issued: 2011
- Authors: Hurbissoon, Roneesh Mehta
- Date: 2011
- Subjects: Sustainable construction , Architecture and energy conservation , Construction industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9722 , http://hdl.handle.net/10948/1379 , Sustainable construction , Architecture and energy conservation , Construction industry
- Description: The Earth's health is deteriorating and will deteriorate even more rapidly unless people adopt eco-friendly policies. Green building has long been a concept but it has not yet been universally applied in practice. The concept of sustainability emerged in the 1970s and can be associated with the energy crisis and environmental pollution concerns. This research is aimed at investigating whether building “green” is more demanding than non-green buildings in terms of cost and the use of green materials against traditional materials; whether professionals in the construction industry are knowledgeable in terms of green buildings; and lastly, to determine whether green buildings are contributing significantly to the environment. The literature reviewed and results of quantitative research amongst professionals from the Island of Mauritius formed the basis of the study. The study revealed that green building is expensive relative to traditional buildings considering. However, the concepts employed (for example: lower energy use, less waste disposal, lower water usage, and sustainable design) provide green buildings with long term savings. Furthermore, the scarcity of natural materials makes it expensive. The study also showed that contractors and professionals have a preference for traditional materials over green materials thus making them more familiar with traditional materials. Contractors and professionals are believed to understand green materials only on a limited basis. This may be attributed to the specific environmental issues involved; however, the research revealed that the professionals are familiar with the basic concepts of green buildings. Lastly, the research showed that green building is still at its infancy but the benefits of green buildings are understood; resulting in green buildings having a good growth potential. The study should be valuable to construction industry professional and clients.
- Full Text:
- Date Issued: 2011
The effect of point of substitution and silver based nanoparticles on the photophysical and optical nonlinearity of indium carboxyphenoxy phthalocyanine
- Oluwole, David O, Ngxeke, Sixolisile M, Britton, Jonathan, Nyokong, Tebello
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
- Full Text:
- Date Issued: 2017
Enhanced optical limiting performance in phthalocyanine-quantum dot nanocomposites by free-carrier absorption mechanism
- Sanusi, Kayode, Khene, Samson M, Nyokong, Tebello
- Authors: Sanusi, Kayode , Khene, Samson M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193904 , vital:45404 , xlink:href="https://doi.org/10.1016/j.optmat.2014.07.024"
- Description: Enhanced nonlinear optical properties (in dimethyl sulphoxide) is observed for 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy)phthalocyaninato indium(III) chloride (InPc) when covalently linked to CdSe/ZnS or CdSe quantum dots (QDs). The experimental nonlinear optical parameters were obtained from Z-Scan measurements. Contributions from two-photon absorption (2PA) due to the InPc, and free-carrier absorption (FCA) by QDS have been identified as the main factors responsible for the enhanced optical limiting. The effective nonlinear absorption coefficient for InPc-CdSe/ZnS was found to be 700.0 cm/GW. The FCA cross-sections for InPc-CdSe/ZnS and InPc-CdSe composites were found to be 1.52 × 10−19 and 6.00 × 10−20 cm2 respectively. A much lower limiting threshold of 92 mJ cm−2 was observed for InPc-CdSe/ZnS nanocomposite, hence, making it suitable for use as optical limiting material. Density Functional Theory (DFT) calculations on similar phthalocyanine-quantum dots system was modeled in order to explain the enhancement in the observed nonlinear optical properties of the Pc in the presence of the QDs. The experimentally determined nonlinear optical properties are well within the range of the DFT calculated properties.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Khene, Samson M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193904 , vital:45404 , xlink:href="https://doi.org/10.1016/j.optmat.2014.07.024"
- Description: Enhanced nonlinear optical properties (in dimethyl sulphoxide) is observed for 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy)phthalocyaninato indium(III) chloride (InPc) when covalently linked to CdSe/ZnS or CdSe quantum dots (QDs). The experimental nonlinear optical parameters were obtained from Z-Scan measurements. Contributions from two-photon absorption (2PA) due to the InPc, and free-carrier absorption (FCA) by QDS have been identified as the main factors responsible for the enhanced optical limiting. The effective nonlinear absorption coefficient for InPc-CdSe/ZnS was found to be 700.0 cm/GW. The FCA cross-sections for InPc-CdSe/ZnS and InPc-CdSe composites were found to be 1.52 × 10−19 and 6.00 × 10−20 cm2 respectively. A much lower limiting threshold of 92 mJ cm−2 was observed for InPc-CdSe/ZnS nanocomposite, hence, making it suitable for use as optical limiting material. Density Functional Theory (DFT) calculations on similar phthalocyanine-quantum dots system was modeled in order to explain the enhancement in the observed nonlinear optical properties of the Pc in the presence of the QDs. The experimentally determined nonlinear optical properties are well within the range of the DFT calculated properties.
- Full Text:
- Date Issued: 2014
Features of an annealing-induced thermoluminescence peak in α-Al2O3: C, Mg
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116013 , vital:34289 , DOI: 10.1016/j.optmat.2017.05.034
- Description: We report the thermoluminescence glow curves of beta irradiated single crystal α-Al2O3:C,Mg after annealing at 700 and 900 °C. A glow curve measured at 1 °C/s from samples irradiated to 1 Gy following annealing at 700 and 900 °C shows a high intensity peak at 163 °C and seven secondary peaks of weaker intensity at 43, 73, 100, 195, 280, 329 and 370 °C. Comparing the position of the peaks in the annealed samples with those in an un-annealed one, it is observed that the peak at 100 °C appears only after annealing at and above 700 °C. Kinetic analysis of this annealing-induced peak was carried out using the initial rise, whole glow peak, peak shape, curve fitting and variable heating rate methods. The order of kinetics of the peak was determined as first order using various methods including the Tm-Tstop technique and the dependence of Tm on irradiation dose. The activation energy of the peak is about 1.01 eV and the frequency factor of the order of 1012 s−1. The peak was found to be affected by thermal quenching in analysis based on change of peak intensity with heating rate. The activation energy of thermal quenching was evaluated as 1.06 ± 0.08 eV. We speculate that the annealing-induced peak is due to formation of a new electron trap after destruction of the F22+(2 Mg) centre when the sample is annealed at 700 °C. The annealing-induced peak fades with storage between irradiation and measurement. It was also concluded that electrons from traps corresponding to secondary peaks get re-trapped at the main electron trap.
- Full Text: false
- Date Issued: 2017
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116013 , vital:34289 , DOI: 10.1016/j.optmat.2017.05.034
- Description: We report the thermoluminescence glow curves of beta irradiated single crystal α-Al2O3:C,Mg after annealing at 700 and 900 °C. A glow curve measured at 1 °C/s from samples irradiated to 1 Gy following annealing at 700 and 900 °C shows a high intensity peak at 163 °C and seven secondary peaks of weaker intensity at 43, 73, 100, 195, 280, 329 and 370 °C. Comparing the position of the peaks in the annealed samples with those in an un-annealed one, it is observed that the peak at 100 °C appears only after annealing at and above 700 °C. Kinetic analysis of this annealing-induced peak was carried out using the initial rise, whole glow peak, peak shape, curve fitting and variable heating rate methods. The order of kinetics of the peak was determined as first order using various methods including the Tm-Tstop technique and the dependence of Tm on irradiation dose. The activation energy of the peak is about 1.01 eV and the frequency factor of the order of 1012 s−1. The peak was found to be affected by thermal quenching in analysis based on change of peak intensity with heating rate. The activation energy of thermal quenching was evaluated as 1.06 ± 0.08 eV. We speculate that the annealing-induced peak is due to formation of a new electron trap after destruction of the F22+(2 Mg) centre when the sample is annealed at 700 °C. The annealing-induced peak fades with storage between irradiation and measurement. It was also concluded that electrons from traps corresponding to secondary peaks get re-trapped at the main electron trap.
- Full Text: false
- Date Issued: 2017
Harnessing the energy of the sun
- Authors: Matiwana, Zamuxolo
- Language: English
- Type: Article
- Identifier: vital:7207 , http://hdl.handle.net/10962/d1006410
- Description: Capturing solar energy was the theme of this year's Barker Lecture delivered by Professor Derek Sehlettwein, an expert electrochemist from Justus-Liebig University in Giessen. Germany
- Full Text:
- Authors: Matiwana, Zamuxolo
- Language: English
- Type: Article
- Identifier: vital:7207 , http://hdl.handle.net/10962/d1006410
- Description: Capturing solar energy was the theme of this year's Barker Lecture delivered by Professor Derek Sehlettwein, an expert electrochemist from Justus-Liebig University in Giessen. Germany
- Full Text:
Imidazole-functionalized polymer microspheres and fibers–useful materials for immobilization of oxovanadium (IV) catalysts
- Walmsley, Ryan S, Ogunlaja, Adeniyi S, Coombes, Matthew J, Chidawanyika, Wadzanai J U, Litwinski, Christian, Torto, Nelson, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Walmsley, Ryan S , Ogunlaja, Adeniyi S , Coombes, Matthew J , Chidawanyika, Wadzanai J U , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246041 , vital:51431 , xlink:href="https://doi.org/10.1039/C2JM15485D"
- Description: Both polymer microspheres and microfibers containing the imidazole functionality have been prepared and used to immobilize oxovanadium(IV). The average diameters and BET surface areas of the microspheres were 322 μm and 155 m2 g−1 while the fibers were 1.85 μm and 52 m2 g−1, respectively. XPS and microanalysis confirmed the incorporation of imidazole and vanadium in the polymeric materials. The catalytic activity of both materials was evaluated using the hydrogen peroxide facilitated oxidation of thioanisole. The microspheres were applied in a typical laboratory batch reactor set-up and quantitative conversions (>99%) were obtained in under 240 min with turn-over frequencies ranging from 21.89 to 265.53 h−1, depending on the quantity of catalyst and temperature. The microspherical catalysts also proved to be recyclable with no drop in activity being observed after three successive reactions. The vanadium functionalized fibers were applied in a pseudo continuous flow set-up. Factors influencing the overall conversion and product selectivity, including flow rate and catalyst quantity, were investigated. At flow rates of 1–4 mL h−1 near quantitative conversion was maintained over an extended period. Keeping the mass of catalyst constant (0.025 g) and varying the flow rate from 1–6 mL h−1 resulted in a shift in the formation of the oxidation product methyl phenyl sulfone from 60.1 to 18.6%.
- Full Text:
- Date Issued: 2012
- Authors: Walmsley, Ryan S , Ogunlaja, Adeniyi S , Coombes, Matthew J , Chidawanyika, Wadzanai J U , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246041 , vital:51431 , xlink:href="https://doi.org/10.1039/C2JM15485D"
- Description: Both polymer microspheres and microfibers containing the imidazole functionality have been prepared and used to immobilize oxovanadium(IV). The average diameters and BET surface areas of the microspheres were 322 μm and 155 m2 g−1 while the fibers were 1.85 μm and 52 m2 g−1, respectively. XPS and microanalysis confirmed the incorporation of imidazole and vanadium in the polymeric materials. The catalytic activity of both materials was evaluated using the hydrogen peroxide facilitated oxidation of thioanisole. The microspheres were applied in a typical laboratory batch reactor set-up and quantitative conversions (>99%) were obtained in under 240 min with turn-over frequencies ranging from 21.89 to 265.53 h−1, depending on the quantity of catalyst and temperature. The microspherical catalysts also proved to be recyclable with no drop in activity being observed after three successive reactions. The vanadium functionalized fibers were applied in a pseudo continuous flow set-up. Factors influencing the overall conversion and product selectivity, including flow rate and catalyst quantity, were investigated. At flow rates of 1–4 mL h−1 near quantitative conversion was maintained over an extended period. Keeping the mass of catalyst constant (0.025 g) and varying the flow rate from 1–6 mL h−1 resulted in a shift in the formation of the oxidation product methyl phenyl sulfone from 60.1 to 18.6%.
- Full Text:
- Date Issued: 2012
Synergistic recognition and electrochemical sensing of 17β-Estradiol using ordered molecularly imprinted polymer-graphene oxide-silver nanoparticles composite films
- Regasa, Melkamu Biyana, Nyokong, Tebello
- Authors: Regasa, Melkamu Biyana , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295829 , vital:57382 , xlink:href="https://doi.org/10.1016/j.jelechem.2022.116713"
- Description: Synthetic molecularly imprinted polymers (MIPs) based functional materials become the best alternatives to alleviate the stability and cost issues related to biological receptors commonly used in biochemical sensors. To address this demand, we report the development of a highly selective and sensitive MIPs-based electrochemical sensor for the detection of 17β-estradiol (E2). The sensor was prepared based on the MIP-graphene oxide (GO)-silver nanoparticle (AgNP) nanocomposite functional materials electrodeposited on the surface of the glassy carbon electrode (GCE). At first, AgNp formation was facilitated by using ascorbic acid to reduce and stabilize it. A very stable MIP-GO-AgNP sensing layer with multifunctional units were formed using imidazole as a functional monomer (p-type-electron acceptor), GO (n-type-electron donor), and AgNP by using the electrodeposition method. The role of GO in the system is providing additional functional units to bind the template and improve materials morphology while that of AgNPs is acting as a catalyst and charge carrier. The characterization of the sensing materials was done by using Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy, and cyclic voltammetry. After optimization of the essential parameters, the sensor was successfully applied to detect the target analyte using the square wave voltammetric technique. The prepared sensor exhibited a wide linear range of 10 fM-250 nM with the limit of detection and limit of quantification of 3.01 fM and 10.03 fM, respectively. The high percentage recoveries, sensitivity, repeatability, and easy fabrication of the MIP-GO-AgNP materials made the proposed sensor promising for environmental monitoring applications in the future.
- Full Text:
- Date Issued: 2022
- Authors: Regasa, Melkamu Biyana , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295829 , vital:57382 , xlink:href="https://doi.org/10.1016/j.jelechem.2022.116713"
- Description: Synthetic molecularly imprinted polymers (MIPs) based functional materials become the best alternatives to alleviate the stability and cost issues related to biological receptors commonly used in biochemical sensors. To address this demand, we report the development of a highly selective and sensitive MIPs-based electrochemical sensor for the detection of 17β-estradiol (E2). The sensor was prepared based on the MIP-graphene oxide (GO)-silver nanoparticle (AgNP) nanocomposite functional materials electrodeposited on the surface of the glassy carbon electrode (GCE). At first, AgNp formation was facilitated by using ascorbic acid to reduce and stabilize it. A very stable MIP-GO-AgNP sensing layer with multifunctional units were formed using imidazole as a functional monomer (p-type-electron acceptor), GO (n-type-electron donor), and AgNP by using the electrodeposition method. The role of GO in the system is providing additional functional units to bind the template and improve materials morphology while that of AgNPs is acting as a catalyst and charge carrier. The characterization of the sensing materials was done by using Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy, and cyclic voltammetry. After optimization of the essential parameters, the sensor was successfully applied to detect the target analyte using the square wave voltammetric technique. The prepared sensor exhibited a wide linear range of 10 fM-250 nM with the limit of detection and limit of quantification of 3.01 fM and 10.03 fM, respectively. The high percentage recoveries, sensitivity, repeatability, and easy fabrication of the MIP-GO-AgNP materials made the proposed sensor promising for environmental monitoring applications in the future.
- Full Text:
- Date Issued: 2022
Action research case studies of participatory materials development in two community contexts in Zambia
- Authors: Lupele, Justin Kalaba
- Date: 2003
- Subjects: Community development -- Zambia -- Case studies Environmental education -- Zambia -- Case studies Sustainable development -- Zambia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1417 , http://hdl.handle.net/10962/d1003298
- Description: This research reports on two action research case studies of participatory materials development in two rural community contexts in Zambia, namely Chiawa and Nalusanga. It aims to explore and articulate the relationships between community-based environmental education and participatory materials development in the WWF Zambia Education Project context; clarify participatory materials development processes by identifying the roles of different ‘actors’ in these processes and identify and analyse the contextual and other factors that may influence development and use of environmental education materials in rural communities. These aims were explored by means of a number of action research cycles of inquiry in the two communities. The study also articulates the significance of considering ambivalent globalising influences such as international conferences, debates, overseas development aid, national policies and how these shape and influence materials development work in a local context. In order to gain more insight into the local contexts, I developed contextual profiles on the two communities. These capture the contextual factors that influenced the participatory materials development processes. They include issues such as language, ethnicity, literacy, power relations and the local social economy, amongst others. Although this study has been predominately guided by the socially critical orientation to research and education, I have drawn on aspects of other research orientations. I have also explored some of the emerging critiques of the socially critical orientation. The findings of this study reveal the different roles participants can play in participatory materials development; participatory materials development processes as a learning process; the dynamics of participation in an African context; the role of language and literacy in materials development; the need for open-ended process models of learning amongst adult learners and the importance of merging expert and local knowledge in participatory materials development. This study opens up possibilities for further exploration of participatory materials development processes within the WWF ZEP context and beyond.
- Full Text:
- Date Issued: 2003
- Authors: Lupele, Justin Kalaba
- Date: 2003
- Subjects: Community development -- Zambia -- Case studies Environmental education -- Zambia -- Case studies Sustainable development -- Zambia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1417 , http://hdl.handle.net/10962/d1003298
- Description: This research reports on two action research case studies of participatory materials development in two rural community contexts in Zambia, namely Chiawa and Nalusanga. It aims to explore and articulate the relationships between community-based environmental education and participatory materials development in the WWF Zambia Education Project context; clarify participatory materials development processes by identifying the roles of different ‘actors’ in these processes and identify and analyse the contextual and other factors that may influence development and use of environmental education materials in rural communities. These aims were explored by means of a number of action research cycles of inquiry in the two communities. The study also articulates the significance of considering ambivalent globalising influences such as international conferences, debates, overseas development aid, national policies and how these shape and influence materials development work in a local context. In order to gain more insight into the local contexts, I developed contextual profiles on the two communities. These capture the contextual factors that influenced the participatory materials development processes. They include issues such as language, ethnicity, literacy, power relations and the local social economy, amongst others. Although this study has been predominately guided by the socially critical orientation to research and education, I have drawn on aspects of other research orientations. I have also explored some of the emerging critiques of the socially critical orientation. The findings of this study reveal the different roles participants can play in participatory materials development; participatory materials development processes as a learning process; the dynamics of participation in an African context; the role of language and literacy in materials development; the need for open-ended process models of learning amongst adult learners and the importance of merging expert and local knowledge in participatory materials development. This study opens up possibilities for further exploration of participatory materials development processes within the WWF ZEP context and beyond.
- Full Text:
- Date Issued: 2003
Metal Sulphides and Their Carbon Supported Composites as Platinum-Free Counter Electrodes in Dye-Sensitized Solar Cells: A Review
- Authors: Materials
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/4048 , vital:43997
- Full Text:
- Authors: Materials
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/4048 , vital:43997
- Full Text:
First example of nonlinear optical materials based on nanoconjugates of sandwich phthalocyanines with quantum dots
- Oluwole, David O, Yagodin, Alexey V, Mkhize, Nhlakanipho C, Sekhosana, Kutloana E, Martynov, Alexander G, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Nyokong, Tebello
- Authors: Oluwole, David O , Yagodin, Alexey V , Mkhize, Nhlakanipho C , Sekhosana, Kutloana E , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238014 , vital:50577 , xlink:href="https://doi.org/10.1002/chem.201604401"
- Description: We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3B-type phthalocyanine ligand (2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker EuIII octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm−2 input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Yagodin, Alexey V , Mkhize, Nhlakanipho C , Sekhosana, Kutloana E , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238014 , vital:50577 , xlink:href="https://doi.org/10.1002/chem.201604401"
- Description: We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3B-type phthalocyanine ligand (2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker EuIII octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm−2 input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications.
- Full Text:
- Date Issued: 2017