Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles
- Nwaji, Njemuwa, Oluwole, David O, Mack, John, Louzada, Marcel, Khene, Samson M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
Improved photocatalytic degradation of Orange G using hybrid nanofibers
- Ledwaba, Mpho, Masilela, Nkosiphile, Nyokong, Tebello, Antunes, Edith M
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239632 , vital:50750 , xlink:href="https://doi.org/10.1007/s11051-017-3853-3"
- Description: Functionalised electrospun polyamide-6 (PA-6) nanofibres incorporating gadolinium oxide nanoparticles conjugated to zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) as the sensitizer were prepared for the photocatalytic degradation of Orange G. Fibres incorporating the phthalocyanine alone or a mixture of the nanoparticles and phthalocyanine were also generated. The singlet oxygen-generating ability of the sensitizer was shown to be maintained within the fibre mat, with the singlet oxygen quantum yields increasing upon incorporation of the magnetic nanoparticles. Consequently, the rate of the photodegradation of Orange G was observed to increase with an increase in singlet oxygen quantum yield. A reduction in the half-lives for the functionalised nanofibres was recorded in the presence of the magnetic nanoparticles, indicating an improvement in the efficiency of the degradation process.
- Full Text:
- Date Issued: 2017
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239632 , vital:50750 , xlink:href="https://doi.org/10.1007/s11051-017-3853-3"
- Description: Functionalised electrospun polyamide-6 (PA-6) nanofibres incorporating gadolinium oxide nanoparticles conjugated to zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) as the sensitizer were prepared for the photocatalytic degradation of Orange G. Fibres incorporating the phthalocyanine alone or a mixture of the nanoparticles and phthalocyanine were also generated. The singlet oxygen-generating ability of the sensitizer was shown to be maintained within the fibre mat, with the singlet oxygen quantum yields increasing upon incorporation of the magnetic nanoparticles. Consequently, the rate of the photodegradation of Orange G was observed to increase with an increase in singlet oxygen quantum yield. A reduction in the half-lives for the functionalised nanofibres was recorded in the presence of the magnetic nanoparticles, indicating an improvement in the efficiency of the degradation process.
- Full Text:
- Date Issued: 2017
Improving singlet oxygen generating abilities of phthalocyanines
- Nwahara, Nnamdi, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwahara, Nnamdi , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188943 , vital:44800 , xlink:href="https://doi.org/10.1080/00958972.2017.1313975"
- Description: Glutathione-capped graphene quantum dots (GQDs@GSH) were covalently linked to folic acid (FA). Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was then adsorbed on the GQDs@GSH-FA conjugate to form GQDs@GSH-FA/ClAlTSPc or on GQDs@GSH and pristine GQDs alone to form GQDs@GSH/ClAlTSPc and GQDs/ClAlTSPc, respectively. We report for the first time on the photophysicochemical behavior of the resulting nanoconjugates. The fluorescence quantum yields of pristine GQDs, GQDS@GSH, or GQDs@GSH-FA conjugate were quenched upon non-covalent interaction (π–π) with ClAlTSPc. There was an increase in triplet quantum yields from 0.38 for ClAlTSPc alone to 0.60, 0.75, and 0.73 when ClAlTSPc was linked to pristine GQDs, GQDs@GSH, and GQDs@GSH-FA, respectively. The singlet oxygen quantum yields also increased from 0.37 for ClAlTSPc alone to 0.42 (for ClALTSPc with pristine GQDs), 0.52 (for ClAlTSPc with GQDs@GSH), and 0.54 (for ClAlTSPc with GQDs@GSH-FA). Thus, the present work may lead to a new generation of carbon-based nanomaterial photodynamic therapy agents with overall performance superior to conventional agents in terms of singlet oxygen generation, water dispersibility, and biocompatibility.
- Full Text:
- Date Issued: 2017
- Authors: Nwahara, Nnamdi , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188943 , vital:44800 , xlink:href="https://doi.org/10.1080/00958972.2017.1313975"
- Description: Glutathione-capped graphene quantum dots (GQDs@GSH) were covalently linked to folic acid (FA). Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was then adsorbed on the GQDs@GSH-FA conjugate to form GQDs@GSH-FA/ClAlTSPc or on GQDs@GSH and pristine GQDs alone to form GQDs@GSH/ClAlTSPc and GQDs/ClAlTSPc, respectively. We report for the first time on the photophysicochemical behavior of the resulting nanoconjugates. The fluorescence quantum yields of pristine GQDs, GQDS@GSH, or GQDs@GSH-FA conjugate were quenched upon non-covalent interaction (π–π) with ClAlTSPc. There was an increase in triplet quantum yields from 0.38 for ClAlTSPc alone to 0.60, 0.75, and 0.73 when ClAlTSPc was linked to pristine GQDs, GQDs@GSH, and GQDs@GSH-FA, respectively. The singlet oxygen quantum yields also increased from 0.37 for ClAlTSPc alone to 0.42 (for ClALTSPc with pristine GQDs), 0.52 (for ClAlTSPc with GQDs@GSH), and 0.54 (for ClAlTSPc with GQDs@GSH-FA). Thus, the present work may lead to a new generation of carbon-based nanomaterial photodynamic therapy agents with overall performance superior to conventional agents in terms of singlet oxygen generation, water dispersibility, and biocompatibility.
- Full Text:
- Date Issued: 2017
Integrating Afrocentric approaches for meaningful learning of science concepts
- Chikunda, Charles, Ngcoza, Kenneth M
- Authors: Chikunda, Charles , Ngcoza, Kenneth M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436248 , vital:73252 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_
- Description: Economic and social development in any modern country re-lies heavily on a sound scientific and technological base. Es-sentially, science constitutes an area of any nation’s education system where many of the skills that are needed to stimulate development are learned, such as securing good health, fighting diseases, protecting the environment, farming and de-veloping agriculture and developing new industries and tech-nologies and even building resilience to climate change. There is a need therefore for a country to harness the intellectual and scientific capacity of its young people. Ironically, however, sci-ence (especially physical sciences) is one of the least popular areas within the educational system of most developing countries. Research shows that students’ and especially girls’ low interest in science and their relatively negative attitudes are at least partially attributed to the way science is taught at school.
- Full Text:
- Date Issued: 2017
- Authors: Chikunda, Charles , Ngcoza, Kenneth M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436248 , vital:73252 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_
- Description: Economic and social development in any modern country re-lies heavily on a sound scientific and technological base. Es-sentially, science constitutes an area of any nation’s education system where many of the skills that are needed to stimulate development are learned, such as securing good health, fighting diseases, protecting the environment, farming and de-veloping agriculture and developing new industries and tech-nologies and even building resilience to climate change. There is a need therefore for a country to harness the intellectual and scientific capacity of its young people. Ironically, however, sci-ence (especially physical sciences) is one of the least popular areas within the educational system of most developing countries. Research shows that students’ and especially girls’ low interest in science and their relatively negative attitudes are at least partially attributed to the way science is taught at school.
- Full Text:
- Date Issued: 2017
Integrating biodiversity considerations into urban golf courses: Managers’ perceptions and woody plant diversity in the Eastern Cape, South Africa
- Jarrett, Mitchell, Shackleton, Charlie M
- Authors: Jarrett, Mitchell , Shackleton, Charlie M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180353 , vital:43356 , xlink:href="https://doi.org/10.1080/1747423X.2017.1325525"
- Description: Rapid rates of urbanisation affect biodiversity through habitat fragmentation and loss. Because urban golf courses are large green spaces, they potentially harbour much biodiversity if managed for such. The area of untransformed land of golf courses in the Eastern Cape (South Africa) was determined using Geographic Information System (GIS), the woody plant composition of a subsample was determined by field sampling and the greenkeepers were interviewed. There was a significant relationship between climate and woody cover, species richness and percentage native plants but not species diversity. There was no relationship between management scores and species richness, diversity and percentage native. Significant relationships were evident between woody plant species richness and course income, number of grounds staff, number of club members and greenkeepers’ years of experience. These results suggest a complex suite of factors that play a role in the woody plant composition of urban golf courses and their contribution to urban biodiversity.
- Full Text:
- Date Issued: 2017
- Authors: Jarrett, Mitchell , Shackleton, Charlie M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180353 , vital:43356 , xlink:href="https://doi.org/10.1080/1747423X.2017.1325525"
- Description: Rapid rates of urbanisation affect biodiversity through habitat fragmentation and loss. Because urban golf courses are large green spaces, they potentially harbour much biodiversity if managed for such. The area of untransformed land of golf courses in the Eastern Cape (South Africa) was determined using Geographic Information System (GIS), the woody plant composition of a subsample was determined by field sampling and the greenkeepers were interviewed. There was a significant relationship between climate and woody cover, species richness and percentage native plants but not species diversity. There was no relationship between management scores and species richness, diversity and percentage native. Significant relationships were evident between woody plant species richness and course income, number of grounds staff, number of club members and greenkeepers’ years of experience. These results suggest a complex suite of factors that play a role in the woody plant composition of urban golf courses and their contribution to urban biodiversity.
- Full Text:
- Date Issued: 2017
Introduction: Researching sustainable development learning pathways towards progression in learning and work
- Lotz-Sisitka, Heila, Ramsarup, Preesha, Bolton, Heidi
- Authors: Lotz-Sisitka, Heila , Ramsarup, Preesha , Bolton, Heidi
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , bulletin
- Identifier: http://hdl.handle.net/10962/436401 , vital:73269 , ISBN bulletin , https://www.saqa.org.za/wp-content/uploads/2023/02/SAQA-Bulletin-2017-1.pdf#page=37
- Description: Environment and sustainable development issues are increasingly seen as complex, multi-faceted and integral to social and economic development, as can be seen from the recently proclaimed sustainable development goals (www.globalgoals.org1 ). As societies grapple with the rapid and catastrophic effects of environmental degradation, anthropogenic earth system change and a long history of unsustainable development, educa-tional systems have had to attempt to comprehend meaningfully, the im-plications. Within post-apartheid South Africa, these challenges are mark-edly more complex. In a country facing fundamental national transfor-mation on every front, the environment and sustainable development discourses are raising significant new challenges for work and learning systems.
- Full Text:
- Date Issued: 2017
- Authors: Lotz-Sisitka, Heila , Ramsarup, Preesha , Bolton, Heidi
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , bulletin
- Identifier: http://hdl.handle.net/10962/436401 , vital:73269 , ISBN bulletin , https://www.saqa.org.za/wp-content/uploads/2023/02/SAQA-Bulletin-2017-1.pdf#page=37
- Description: Environment and sustainable development issues are increasingly seen as complex, multi-faceted and integral to social and economic development, as can be seen from the recently proclaimed sustainable development goals (www.globalgoals.org1 ). As societies grapple with the rapid and catastrophic effects of environmental degradation, anthropogenic earth system change and a long history of unsustainable development, educa-tional systems have had to attempt to comprehend meaningfully, the im-plications. Within post-apartheid South Africa, these challenges are mark-edly more complex. In a country facing fundamental national transfor-mation on every front, the environment and sustainable development discourses are raising significant new challenges for work and learning systems.
- Full Text:
- Date Issued: 2017
Investigating the effects various compilers have on the electromagnetic signature of a cryptographic executable
- Frieslaar, Ibraheem, Irwin, Barry V W
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430207 , vital:72673 , https://doi.org/10.1145/3129416.3129436
- Description: This research investigates changes in the electromagnetic (EM) signatures of a cryptographic binary executable based on compile-time parameters to the GNU and clang compilers. The source code was compiled and executed on a Raspberry Pi 2, which utilizes the ARMv7 CPU. Various optimization flags are enabled at compile-time and the output of the binary executable's EM signatures are captured at run-time. It is demonstrated that GNU and clang compilers produced different EM signature on program execution. The results indicated while utilizing the O3 optimization flag, the EM signature of the program changes. Additionally, the g++ compiler demonstrated fewer instructions were required to run the executable; this related to fewer EM emissions leaked. The EM data from the various compilers under different optimization levels was used as input data for a correlation power analysis attack. The results indicated that partial AES-128 encryption keys was possible. In addition, the fewest subkeys recovered was when the clang compiler was used with level O2 optimization. Finally, the research was able to recover 15 of 16 AES-128 cryptographic algorithm's subkeys, from the the Pi.
- Full Text:
- Date Issued: 2017
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430207 , vital:72673 , https://doi.org/10.1145/3129416.3129436
- Description: This research investigates changes in the electromagnetic (EM) signatures of a cryptographic binary executable based on compile-time parameters to the GNU and clang compilers. The source code was compiled and executed on a Raspberry Pi 2, which utilizes the ARMv7 CPU. Various optimization flags are enabled at compile-time and the output of the binary executable's EM signatures are captured at run-time. It is demonstrated that GNU and clang compilers produced different EM signature on program execution. The results indicated while utilizing the O3 optimization flag, the EM signature of the program changes. Additionally, the g++ compiler demonstrated fewer instructions were required to run the executable; this related to fewer EM emissions leaked. The EM data from the various compilers under different optimization levels was used as input data for a correlation power analysis attack. The results indicated that partial AES-128 encryption keys was possible. In addition, the fewest subkeys recovered was when the clang compiler was used with level O2 optimization. Finally, the research was able to recover 15 of 16 AES-128 cryptographic algorithm's subkeys, from the the Pi.
- Full Text:
- Date Issued: 2017
Investigating the electromagnetic side channel leakage from a raspberry pi
- Frieslaar, Ibraheem, Irwin, Barry V W
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429548 , vital:72621 , https://ieeexplore.ieee.org/abstract/document/8251771
- Description: This research investigates the Electromagnetic (EM) side channel leakage of a Raspberry Pi 2 B+. An evaluation is performed on the EM leakage as the device executes the AES-128 cryptographic algorithm contained in the Crypto++ library in a threaded environment. Four multi-threaded implementations are evaluated. These implementations are Portable Operating System Interface Threads, C++11 threads, Threading Building Blocks, and OpenMP threads. It is demonstrated that the various thread techniques have distinct variations in frequency and shape as EM emanations is leaked from the Raspberry Pi. Additionally, noise is introduced while the cryptographic algorithm executes. The results indicates that tt is still possible to visibly see the execution of the cryptographic algorithm. However, out of 50 occasions the cryptographic execution was not detected 32 times. It was further identified when calculating prime numbers, the cryptographic algorithm becomes hidden. Furthermore, the analysis pointed in the direction that when high prime numbers are calculated there is a window where the cryptographic algorithm can not be seen visibly in the EM spectrum.
- Full Text:
- Date Issued: 2017
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429548 , vital:72621 , https://ieeexplore.ieee.org/abstract/document/8251771
- Description: This research investigates the Electromagnetic (EM) side channel leakage of a Raspberry Pi 2 B+. An evaluation is performed on the EM leakage as the device executes the AES-128 cryptographic algorithm contained in the Crypto++ library in a threaded environment. Four multi-threaded implementations are evaluated. These implementations are Portable Operating System Interface Threads, C++11 threads, Threading Building Blocks, and OpenMP threads. It is demonstrated that the various thread techniques have distinct variations in frequency and shape as EM emanations is leaked from the Raspberry Pi. Additionally, noise is introduced while the cryptographic algorithm executes. The results indicates that tt is still possible to visibly see the execution of the cryptographic algorithm. However, out of 50 occasions the cryptographic execution was not detected 32 times. It was further identified when calculating prime numbers, the cryptographic algorithm becomes hidden. Furthermore, the analysis pointed in the direction that when high prime numbers are calculated there is a window where the cryptographic algorithm can not be seen visibly in the EM spectrum.
- Full Text:
- Date Issued: 2017
Investigating the utilization of the secure hash algorithm to generate electromagnetic noise
- Frieslaar, Ibraheem, Irwin, Barry V W
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430222 , vital:72674 , https://doi.org/10.1145/3163080.3163089
- Description: This research introduces an electromagnetic (EM) noise generator known as the FRIES noise generator to mitigate and obfuscate Side Channel Analysis (SCA) attacks against a Raspberry Pi. The FRIES noise generator utilizes the implementation of the Secure Hash Algorithm (SHA) from OpenSSL to generate white noise within the EM spectrum. This research further contributes to the body of knowledge by demonstrating that the SHA implementation of libcrypto++ and OpenSSL had different EM signatures. It was further revealed that as a more secure implementation of the SHA was executed additional data lines were used, resulting in increased EM emissions. It was demonstrated that the OpenSSL implementations of the SHA was more optimized as opposed to the libcrypto++ implementation by utilizing less resources and not leaving the device in a bottleneck. The FRIES daemon added noise to the EM leakage which prevents the visual location of the AES-128 cryptographic implementation. Finally, the cross-correlation test demonstrated that the EM features of the AES-128 algorithm was not detected within the FRIES noise.
- Full Text:
- Date Issued: 2017
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430222 , vital:72674 , https://doi.org/10.1145/3163080.3163089
- Description: This research introduces an electromagnetic (EM) noise generator known as the FRIES noise generator to mitigate and obfuscate Side Channel Analysis (SCA) attacks against a Raspberry Pi. The FRIES noise generator utilizes the implementation of the Secure Hash Algorithm (SHA) from OpenSSL to generate white noise within the EM spectrum. This research further contributes to the body of knowledge by demonstrating that the SHA implementation of libcrypto++ and OpenSSL had different EM signatures. It was further revealed that as a more secure implementation of the SHA was executed additional data lines were used, resulting in increased EM emissions. It was demonstrated that the OpenSSL implementations of the SHA was more optimized as opposed to the libcrypto++ implementation by utilizing less resources and not leaving the device in a bottleneck. The FRIES daemon added noise to the EM leakage which prevents the visual location of the AES-128 cryptographic implementation. Finally, the cross-correlation test demonstrated that the EM features of the AES-128 algorithm was not detected within the FRIES noise.
- Full Text:
- Date Issued: 2017
Investigation of photophysicochemical properties of zinc phthalocyanines conjugated to metallic nanoparticles
- Dube, Edith, Nwaji, Njemuwa, Oluwole, David O, Mack, John, Nyokong, Tebello
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
Issues-Based Enquiry: An Enabling Pedagogy for ESD in Teacher Education and School Geography
- Authors: Wilmot, Diana P
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436266 , vital:73253 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_10
- Description: This chapter addresses the need for innovations in geography teacher education programmes in a developing world context. More specifically, it responds to the need for practical ‘how to’ examples for ESD integration into school geography by de-scribing a pedagogical experiment that was piloted with in-service Namibian teachers and education development offic-ers (EDOs) enrolled for a Bachelor of Education (Honours) de-gree in 2014. The theoretical constructs underpinning the ex-periment’s design and pedagogical approach as well as the teacher professional development model are described. This is followed by a description and justification of the methodology used to answer the research question: ‘How can issues-based enquiry enable the integration of ESD at the micro level of the classroom?’ The findings of the experiment provide evidence of how issues-based enquiry, underpinned by active learning and constructivist epistemology and a model of teacher pro-fessional development located in reflexive practice, enabled the teachers to acquire foundational knowledge and pedagog-ical content knowledge for effective integration of ESD into school geography. This chapter may offer other teacher educators some guidelines on how to develop teacher capacity to integrate ESD into their own programmes.
- Full Text:
- Date Issued: 2017
- Authors: Wilmot, Diana P
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436266 , vital:73253 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_10
- Description: This chapter addresses the need for innovations in geography teacher education programmes in a developing world context. More specifically, it responds to the need for practical ‘how to’ examples for ESD integration into school geography by de-scribing a pedagogical experiment that was piloted with in-service Namibian teachers and education development offic-ers (EDOs) enrolled for a Bachelor of Education (Honours) de-gree in 2014. The theoretical constructs underpinning the ex-periment’s design and pedagogical approach as well as the teacher professional development model are described. This is followed by a description and justification of the methodology used to answer the research question: ‘How can issues-based enquiry enable the integration of ESD at the micro level of the classroom?’ The findings of the experiment provide evidence of how issues-based enquiry, underpinned by active learning and constructivist epistemology and a model of teacher pro-fessional development located in reflexive practice, enabled the teachers to acquire foundational knowledge and pedagog-ical content knowledge for effective integration of ESD into school geography. This chapter may offer other teacher educators some guidelines on how to develop teacher capacity to integrate ESD into their own programmes.
- Full Text:
- Date Issued: 2017
Land cover models to predict non-point nutrient inputs for selected biomes in South Africa
- Slaughter, Andrew R, Mantel, Sukhmani K
- Authors: Slaughter, Andrew R , Mantel, Sukhmani K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438152 , vital:73439 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/3390.pdf
- Description: WQSAM is a practical water quality model for use in guiding southern African water quality management. However, the estimation of non-point nutrient inputs within WQSAM is uncertain, as it is achieved through a combination of calibration and expert knowledge. Non-point source loads can be correlated to particular land cover types. Although observed water quality data through which non-point source loads can be estimated are scarce, land cover databases exist covering the entire area of South Africa. To reduce the uncertainty associated with estimat-ing non-point source loads, this study describes a formal model to link the nutrient signatures of incremental flow to land cover. Study catch-ments incorporating the fynbos, grassland, savanna and thicket biomes were identified. Instream nutrients of 25 sites were modelled using WQSAM and calibrated against observed data. Multiple regression was used to investigate the relationships between the calibrated nutrient signatures of incremental flow from WQSAM and land cover within study sites. The regression models reflected greater non-point loads from cultivation-and urban-related land cover categories. The nutrient signatures of incremental flow obtained through the multiple regres-sions were consistent with those obtained through calibration of the WQSAM model at higher signature values, whereas discrepancies were evident at lower values. It is argued that this formal modelling ap-proach for linking land cover to nutrient signatures of incremental flow can be implemented for situations where it is known that there are strong non-point inputs of nutrients into a river reach. The statistical model presented in the current study could potentially be applied as an alternative to the water quality model as a relatively simple method to estimate non-point source loads of nutrients from tributary catchments in South Africa.
- Full Text:
- Date Issued: 2017
- Authors: Slaughter, Andrew R , Mantel, Sukhmani K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438152 , vital:73439 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/3390.pdf
- Description: WQSAM is a practical water quality model for use in guiding southern African water quality management. However, the estimation of non-point nutrient inputs within WQSAM is uncertain, as it is achieved through a combination of calibration and expert knowledge. Non-point source loads can be correlated to particular land cover types. Although observed water quality data through which non-point source loads can be estimated are scarce, land cover databases exist covering the entire area of South Africa. To reduce the uncertainty associated with estimat-ing non-point source loads, this study describes a formal model to link the nutrient signatures of incremental flow to land cover. Study catch-ments incorporating the fynbos, grassland, savanna and thicket biomes were identified. Instream nutrients of 25 sites were modelled using WQSAM and calibrated against observed data. Multiple regression was used to investigate the relationships between the calibrated nutrient signatures of incremental flow from WQSAM and land cover within study sites. The regression models reflected greater non-point loads from cultivation-and urban-related land cover categories. The nutrient signatures of incremental flow obtained through the multiple regres-sions were consistent with those obtained through calibration of the WQSAM model at higher signature values, whereas discrepancies were evident at lower values. It is argued that this formal modelling ap-proach for linking land cover to nutrient signatures of incremental flow can be implemented for situations where it is known that there are strong non-point inputs of nutrients into a river reach. The statistical model presented in the current study could potentially be applied as an alternative to the water quality model as a relatively simple method to estimate non-point source loads of nutrients from tributary catchments in South Africa.
- Full Text:
- Date Issued: 2017
Laser induced photodegradation of Orange G using phthalocyanine–cobalt ferrite magnetic nanoparticle conjugates electrospun in polystyrene nanofibers
- Mapukata, Sivuyisiwe, Chindeka, Francis, Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Mapukata, Sivuyisiwe , Chindeka, Francis , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188617 , vital:44769 , xlink:href="https://doi.org/10.1016/j.mcat.2017.06.028"
- Description: Conjugates of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) and zinc tetraaminophenoxy phthalocyanine (ZnTAPPc) with amine and carboxyl functionalised cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs), respectively were electrospun into polystyrene (PS) fibers. The resulting composites; ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on their photophysical properties and photocatalytic efficiencies in degrading Orange G (OG) using laser as the photoexcitation source. The photocatalytic efficiencies of ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on them having different lengths in the linkage chains between the Pcs and CoFe2O4 MNPs and different sizes. Covalent linkage of the Pcs to the CoFe2O4 MNPs enhanced the singlet oxygen and reactive oxygen species (ROS) production of the Pcs and CoFe2O4, respectively hence ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were found to be more effective photocatalysts than their respective Pcs and CoFe2O4 MNPs. Moreover, the kinetic analyses of the photodecomposition of OG showed that the degradation was in agreement with both pseudo-first order kinetics and followed the Langmuir–Hinshelwood model.
- Full Text:
- Date Issued: 2017
- Authors: Mapukata, Sivuyisiwe , Chindeka, Francis , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188617 , vital:44769 , xlink:href="https://doi.org/10.1016/j.mcat.2017.06.028"
- Description: Conjugates of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) and zinc tetraaminophenoxy phthalocyanine (ZnTAPPc) with amine and carboxyl functionalised cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs), respectively were electrospun into polystyrene (PS) fibers. The resulting composites; ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on their photophysical properties and photocatalytic efficiencies in degrading Orange G (OG) using laser as the photoexcitation source. The photocatalytic efficiencies of ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on them having different lengths in the linkage chains between the Pcs and CoFe2O4 MNPs and different sizes. Covalent linkage of the Pcs to the CoFe2O4 MNPs enhanced the singlet oxygen and reactive oxygen species (ROS) production of the Pcs and CoFe2O4, respectively hence ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were found to be more effective photocatalysts than their respective Pcs and CoFe2O4 MNPs. Moreover, the kinetic analyses of the photodecomposition of OG showed that the degradation was in agreement with both pseudo-first order kinetics and followed the Langmuir–Hinshelwood model.
- Full Text:
- Date Issued: 2017
Learning pathways and articulation: Early conceptual explorations and implications for research design (s)
- Lotz-Sisitka, Heila, Ramsarup, Preesha
- Authors: Lotz-Sisitka, Heila , Ramsarup, Preesha
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , bulletin
- Identifier: http://hdl.handle.net/10962/436388 , vital:73268 , ISBN bulletin , https://www.saqa.org.za/wp-content/uploads/2023/02/SAQA-Bulletin-2017-1.pdf#page=37
- Description: This paper is an introductory, exploratory paper which opened up the ter-rain for a second phase of the South African Qualifications Authority (SAQA)-Rhodes University research partnership focusing on change-oriented workplace learning and sustainability practices, with an emphasis on learning pathways (the main period being 2011-2013, ongoing until 2016). The paper reviews early conceptual explorations of learning path-ways and articulation questions, as these relate to a transversal issue8 in the National Qualifications Framework (NQF), namely environment and sustainable development.
- Full Text:
- Date Issued: 2017
- Authors: Lotz-Sisitka, Heila , Ramsarup, Preesha
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , bulletin
- Identifier: http://hdl.handle.net/10962/436388 , vital:73268 , ISBN bulletin , https://www.saqa.org.za/wp-content/uploads/2023/02/SAQA-Bulletin-2017-1.pdf#page=37
- Description: This paper is an introductory, exploratory paper which opened up the ter-rain for a second phase of the South African Qualifications Authority (SAQA)-Rhodes University research partnership focusing on change-oriented workplace learning and sustainability practices, with an emphasis on learning pathways (the main period being 2011-2013, ongoing until 2016). The paper reviews early conceptual explorations of learning path-ways and articulation questions, as these relate to a transversal issue8 in the National Qualifications Framework (NQF), namely environment and sustainable development.
- Full Text:
- Date Issued: 2017
Life-histories explain the conservation status of two estuary-associated pipefishes
- Whitfield, Alan K, Mkare, Thomas K, Teske, Peter R, James, Nicola C, Cowley, Paul D
- Authors: Whitfield, Alan K , Mkare, Thomas K , Teske, Peter R , James, Nicola C , Cowley, Paul D
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445087 , vital:74346 , https://doi.org/10.1016/j.biocon.2017.06.024
- Description: Two endemic southern African pipefish species (Teleostei: Syngnathidae) co-occur in estuaries on the southeast coast of South Africa. The larger longsnout pipefish, Syngnathus temminckii, is abundant and has a wide range that comprises coastal and estuarine habitats in all three of the region's marine biogeographic provinces. In contrast, the smaller estuarine pipefish S. watermeyeri is critically endangered, and confined to a few warm-temperate estuaries. Here, we explore reasons for these considerable differences in conservation status.
- Full Text:
- Date Issued: 2017
- Authors: Whitfield, Alan K , Mkare, Thomas K , Teske, Peter R , James, Nicola C , Cowley, Paul D
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445087 , vital:74346 , https://doi.org/10.1016/j.biocon.2017.06.024
- Description: Two endemic southern African pipefish species (Teleostei: Syngnathidae) co-occur in estuaries on the southeast coast of South Africa. The larger longsnout pipefish, Syngnathus temminckii, is abundant and has a wide range that comprises coastal and estuarine habitats in all three of the region's marine biogeographic provinces. In contrast, the smaller estuarine pipefish S. watermeyeri is critically endangered, and confined to a few warm-temperate estuaries. Here, we explore reasons for these considerable differences in conservation status.
- Full Text:
- Date Issued: 2017
Local knowledge on the uses, habitat, and change in abundance of multipurpose mimusops species in Benin
- Sinasson Gisèle K, Shackleton, Charlie M, Assogbadjo, Achille E, Sinsin, Brice
- Authors: Sinasson Gisèle K , Shackleton, Charlie M , Assogbadjo, Achille E , Sinsin, Brice
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181105 , vital:43699 , xlink:href="https://doi.org/10.1007/s12231-017-9370-6"
- Description: Multipurpose NTFP species typically experience higher harvest demand because of their multiple uses, which, when combined with unsustainable land use practices, may threaten population viability. We assessed local knowledge on the uses, habitat, and population status of Mimusops andongensis and Mimusops kummel, both multipurpose NTFP species in Benin, to promote their valorization and conservation and thus sustain local knowledge on their uses for domestication issues. One hundred households were randomly selected for structured interviews for M. andongensis and 500 for M. kummel. The relationship between age, sex, and ethnic groups and the species uses was assessed using comparison and correspondence analyses. Nearly all organs of the species were used. Both species were mainly exploited for medicinal purposes but also in construction and as firewood. We found similarities in some uses of the species organs, although the species occur in different ecological zones and are used by different ethnic groups. This result should be considered for the valorization of the species. Most informants reported that populations of M. andongensis were decreasing, although some felt that they were increasing, whereas less than one-third said that M. kummel was decreasing. There were strong relationships between gender, age, and ethnic affiliation of the users and the exploited organs of both species. Potential uses exist based on both the past and current uses of the species and in comparison to other countries where they are exploited. Local ethnoecological knowledge and practices will help to valorize and conserve the species. However, further research on the species’ seed germination and propagation ability are also necessary.
- Full Text:
- Date Issued: 2017
- Authors: Sinasson Gisèle K , Shackleton, Charlie M , Assogbadjo, Achille E , Sinsin, Brice
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181105 , vital:43699 , xlink:href="https://doi.org/10.1007/s12231-017-9370-6"
- Description: Multipurpose NTFP species typically experience higher harvest demand because of their multiple uses, which, when combined with unsustainable land use practices, may threaten population viability. We assessed local knowledge on the uses, habitat, and population status of Mimusops andongensis and Mimusops kummel, both multipurpose NTFP species in Benin, to promote their valorization and conservation and thus sustain local knowledge on their uses for domestication issues. One hundred households were randomly selected for structured interviews for M. andongensis and 500 for M. kummel. The relationship between age, sex, and ethnic groups and the species uses was assessed using comparison and correspondence analyses. Nearly all organs of the species were used. Both species were mainly exploited for medicinal purposes but also in construction and as firewood. We found similarities in some uses of the species organs, although the species occur in different ecological zones and are used by different ethnic groups. This result should be considered for the valorization of the species. Most informants reported that populations of M. andongensis were decreasing, although some felt that they were increasing, whereas less than one-third said that M. kummel was decreasing. There were strong relationships between gender, age, and ethnic affiliation of the users and the exploited organs of both species. Potential uses exist based on both the past and current uses of the species and in comparison to other countries where they are exploited. Local ethnoecological knowledge and practices will help to valorize and conserve the species. However, further research on the species’ seed germination and propagation ability are also necessary.
- Full Text:
- Date Issued: 2017
Macroinvertebrate functional organisation along the longitudinal gradient of an austral temperate river
- Moyo, Sydney, Richoux, Nicole B
- Authors: Moyo, Sydney , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443178 , vital:74086 , https://doi.org/10.1080/15627020.2017.1354721
- Description: The Kowie River, a relatively pristine system in South Africa, was sampled on four occasions over one year to determine if relative abundances of functional feeding groups (FFGs) of invertebrates changed along the longitudinal gradient, and if these changes matched predictions of the river continuum concept (RCC). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50–83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was 10% at all sites and times). The changes in relative abundances of the different FFGs did not always follow the predictions of the RCC, as there were no correlations of community structure with river width or canopy cover in some seasons; however, some predictions of the RCC were supported, as a dominance of filterers (with relatively small contributions from shredders and grazers) and a consistent presence of predators were recorded. The FFG abundances were correlated with water velocity and total dissolved solids. Broadly, shifts in relative abundances of FFGs along the river continuum could not be explained by physical attributes alone, and were probably influenced by the availability of food and the chemistry of the river. Our findings highlight the need for theoretical and field studies across a broad array of African systems to refine the applicability of the RCC and FFG classifications to further develop models of ecosystem function.
- Full Text:
- Date Issued: 2017
- Authors: Moyo, Sydney , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443178 , vital:74086 , https://doi.org/10.1080/15627020.2017.1354721
- Description: The Kowie River, a relatively pristine system in South Africa, was sampled on four occasions over one year to determine if relative abundances of functional feeding groups (FFGs) of invertebrates changed along the longitudinal gradient, and if these changes matched predictions of the river continuum concept (RCC). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50–83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was 10% at all sites and times). The changes in relative abundances of the different FFGs did not always follow the predictions of the RCC, as there were no correlations of community structure with river width or canopy cover in some seasons; however, some predictions of the RCC were supported, as a dominance of filterers (with relatively small contributions from shredders and grazers) and a consistent presence of predators were recorded. The FFG abundances were correlated with water velocity and total dissolved solids. Broadly, shifts in relative abundances of FFGs along the river continuum could not be explained by physical attributes alone, and were probably influenced by the availability of food and the chemistry of the river. Our findings highlight the need for theoretical and field studies across a broad array of African systems to refine the applicability of the RCC and FFG classifications to further develop models of ecosystem function.
- Full Text:
- Date Issued: 2017
Macroinvertebrate functional organisation along the longitudinal gradient of an austral temperate river
- Moyo, Sydney, Richoux, Nicole B
- Authors: Moyo, Sydney , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456280 , vital:75499 , xlink:href=" https://doi.org/10.1080/15627020.2017.1354721"
- Description: The Kowie River, a relatively pristine system in South Africa, was sampled on four occasions over one year to determine if relative abundances of functional feeding groups (FFGs) of invertebrates changed along the longitudinal gradient, and if these changes matched predictions of the river continuum concept (RCC). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50–83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was less than 10% at all sites and times). The changes in relative abundances of the different FFGs did not always follow the predictions of the RCC, as there were no correlations of community structure with river width or canopy cover in some seasons; however, some predictions of the RCC were supported, as a dominance of filterers (with relatively small contributions from shredders and grazers) and a consistent presence of predators were recorded. The FFG abundances were correlated with water velocity and total dissolved solids. Broadly, shifts in relative abundances of FFGs along the river continuum could not be explained by physical attributes alone, and were probably influenced by the availability of food and the chemistry of the river. Our findings highlight the need for theoretical and field studies across a broad array of African systems to refine the applicability of the RCC and FFG classifications to further develop models of ecosystem function.
- Full Text:
- Date Issued: 2017
- Authors: Moyo, Sydney , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456280 , vital:75499 , xlink:href=" https://doi.org/10.1080/15627020.2017.1354721"
- Description: The Kowie River, a relatively pristine system in South Africa, was sampled on four occasions over one year to determine if relative abundances of functional feeding groups (FFGs) of invertebrates changed along the longitudinal gradient, and if these changes matched predictions of the river continuum concept (RCC). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50–83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was less than 10% at all sites and times). The changes in relative abundances of the different FFGs did not always follow the predictions of the RCC, as there were no correlations of community structure with river width or canopy cover in some seasons; however, some predictions of the RCC were supported, as a dominance of filterers (with relatively small contributions from shredders and grazers) and a consistent presence of predators were recorded. The FFG abundances were correlated with water velocity and total dissolved solids. Broadly, shifts in relative abundances of FFGs along the river continuum could not be explained by physical attributes alone, and were probably influenced by the availability of food and the chemistry of the river. Our findings highlight the need for theoretical and field studies across a broad array of African systems to refine the applicability of the RCC and FFG classifications to further develop models of ecosystem function.
- Full Text:
- Date Issued: 2017
Mechanism of nucleophilic substitution reactions of 4-(4ˊ-nitro) phenylnitrobenzofurazan ether with aniline in acetonitrile
- Gbayo, Kofoworola, Isanbor, C, Lobb, Kevin A, Oloba-Whenu, O
- Authors: Gbayo, Kofoworola , Isanbor, C , Lobb, Kevin A , Oloba-Whenu, O
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448002 , vital:74690 , xlink:href="https://doi.org/10.1515/psr-2016-0120"
- Description: Rate constants and activation parameters obtained for the nucleophilic aromatic substitution reactions (SNAr) of 4-substitutedphenoxy-7-nitrobenzoxadiazole (1) with aniline in acetonitrile at varying temperature using Nuclear Magnetic Resonance (NMR) techniques were reported. These results were compared with the theoretical study which identifies transformations and intermediates using Density Functional Theory (DFT).
- Full Text:
- Date Issued: 2017
- Authors: Gbayo, Kofoworola , Isanbor, C , Lobb, Kevin A , Oloba-Whenu, O
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448002 , vital:74690 , xlink:href="https://doi.org/10.1515/psr-2016-0120"
- Description: Rate constants and activation parameters obtained for the nucleophilic aromatic substitution reactions (SNAr) of 4-substitutedphenoxy-7-nitrobenzoxadiazole (1) with aniline in acetonitrile at varying temperature using Nuclear Magnetic Resonance (NMR) techniques were reported. These results were compared with the theoretical study which identifies transformations and intermediates using Density Functional Theory (DFT).
- Full Text:
- Date Issued: 2017
Modelling dialectical processes in environmental learning
- Authors: Schudel, Ingrid J
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294409 , vital:57219 , xlink:href="https://doi.org/10.1080/14767430.2017.1288061"
- Description: This paper describes a critical realist intensive case study, which develops and tests a ‘dialectic process model of transformative learning’. The model is inspired by Bhaskar's (1993) onto-axiological chain (or MELD Schema) as outlined in his formulation of dialectical critical realism. The study describes transformative environmental learning processes focusing on food security in two primary schools in rural South Africa. The model elaborates on the four links in the onto-axiological chain by describing four knowledge interests across the two cases: knowledge of ‘what is and what is not’, knowledge of ‘what could be’, knowledge of ‘what should be’, and knowledge of ‘what can be’. The model also highlights the emergent nature of epistemic relations in transformative learning processes. The paper discusses the model in relation to a transformative, open-ended and context specific approach to Environmental Education (EE)/ESD. The paper illustrates that Bhaskar’s MELD is a robust schema for investigating learning-led change in EE and suggests its relevance in other research contexts concerned with societal transformation.
- Full Text:
- Date Issued: 2017
- Authors: Schudel, Ingrid J
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294409 , vital:57219 , xlink:href="https://doi.org/10.1080/14767430.2017.1288061"
- Description: This paper describes a critical realist intensive case study, which develops and tests a ‘dialectic process model of transformative learning’. The model is inspired by Bhaskar's (1993) onto-axiological chain (or MELD Schema) as outlined in his formulation of dialectical critical realism. The study describes transformative environmental learning processes focusing on food security in two primary schools in rural South Africa. The model elaborates on the four links in the onto-axiological chain by describing four knowledge interests across the two cases: knowledge of ‘what is and what is not’, knowledge of ‘what could be’, knowledge of ‘what should be’, and knowledge of ‘what can be’. The model also highlights the emergent nature of epistemic relations in transformative learning processes. The paper discusses the model in relation to a transformative, open-ended and context specific approach to Environmental Education (EE)/ESD. The paper illustrates that Bhaskar’s MELD is a robust schema for investigating learning-led change in EE and suggests its relevance in other research contexts concerned with societal transformation.
- Full Text:
- Date Issued: 2017