A spatio-temporal, landscape perspective on Acacia dealbata invasions and broader land use and cover changes in the northern Eastern Cape, South Africa
- Gouws, Aidan J, Prof.Shackleton, Charlie M
- Authors: Gouws, Aidan J , Prof.Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179670 , vital:43156 , xlink:href="https://doi.org/10.1007/s10661-019-7204-y"
- Description: Biological invasions and human land use both have the potential to drastically alter the patterns and processes of landscapes, driving habitat fragmentation and altering natural disturbance regimes. The proliferation of an invasive species depends on composition and configuration of the landscape, as well as the invasiveness of the species. To effectively manage a highly invasive species, such as Acacia dealbata, it is crucial to understand the historical progression of the invasion within the landscape. This study sought to examine the landscape dynamics of biological invasions by tracking the historical spread of A. dealbata and broader land use/land cover (LULC) changes at different spatiotemporal scales in the northern Eastern Cape. A timeseries of aerial photographs were systematically classified according to designated A. dealbata and LULC categories in ArcGIS to track the changes in the extent and rate of spread of A. dealbata. Markedly dynamic, multi-directional, and spatio-temporally variable LULC transitions were observed across the northern Eastern Cape over the last six decades. A. dealbata frequently retained a high proportion of cover over time, and despite the loss of cover to other LULC classes, a net increase in A. dealbata cover occurred as it spread at an overall annual rate of 0.11–0.21%, occupying approximately 8–18% of land cover across all sampled sites by 2013.
- Full Text:
- Authors: Gouws, Aidan J , Prof.Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179670 , vital:43156 , xlink:href="https://doi.org/10.1007/s10661-019-7204-y"
- Description: Biological invasions and human land use both have the potential to drastically alter the patterns and processes of landscapes, driving habitat fragmentation and altering natural disturbance regimes. The proliferation of an invasive species depends on composition and configuration of the landscape, as well as the invasiveness of the species. To effectively manage a highly invasive species, such as Acacia dealbata, it is crucial to understand the historical progression of the invasion within the landscape. This study sought to examine the landscape dynamics of biological invasions by tracking the historical spread of A. dealbata and broader land use/land cover (LULC) changes at different spatiotemporal scales in the northern Eastern Cape. A timeseries of aerial photographs were systematically classified according to designated A. dealbata and LULC categories in ArcGIS to track the changes in the extent and rate of spread of A. dealbata. Markedly dynamic, multi-directional, and spatio-temporally variable LULC transitions were observed across the northern Eastern Cape over the last six decades. A. dealbata frequently retained a high proportion of cover over time, and despite the loss of cover to other LULC classes, a net increase in A. dealbata cover occurred as it spread at an overall annual rate of 0.11–0.21%, occupying approximately 8–18% of land cover across all sampled sites by 2013.
- Full Text:
Methodological Survey of Simplified TD-DFT Methods for Fast and Accurate Interpretation of UV−Vis−NIR Spectra of Phthalocyanines
- Martynov, Alexander G, Mack, John, May, Aviwe K, Nyokong, Tebello, Gorbunova, Yulia G, Tsivadze, Aslan Yu
- Authors: Martynov, Alexander G , Mack, John , May, Aviwe K , Nyokong, Tebello , Gorbunova, Yulia G , Tsivadze, Aslan Yu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186915 , vital:44547 , xlink:href="https://doi.org/10.1021/acsomega.8b03500"
- Description: A methodological survey of density functional theory (DFT) methods for the prediction of UV−visible (vis)−near-infrared (NIR) spectra of phthalocyanines is reported. Four methods, namely, full time-dependent (TD)-DFT and its Tamm−Dancoff approximation (TDA), together with their simplified modifications (sTD-DFT and sTDA, respectively), were tested by using the examples of unsubstituted and alkoxy-substituted metal-free ligands and zinc complexes. The theoretical results were compared with experimental data derived from UV−visible absorption and magnetic circular dichroism spectroscopy. Seven popular exchange-correlation functionals (BP86, B3LYP, TPSSh, M06, CAM-B3LYP, LC-BLYP, and ωB97X) were tested within these four approaches starting at a relatively modest level using 6-31G(d) basis sets and gas-phase BP86/def2-SVP optimized geometries. A gradual augmentation of the computational levels was used to identify the influence of starting geometry, solvation effects, and basis sets on the results of TD-DFT and sTD-DFT calculations. It was found that although these factors do influence the predicted energies of the vertical excitations, they do not affect the trends predicted in the spectral properties across series of structurally related substituted free bases and metallophthalocyanines. The best accuracy for the gas-phase vertical excitations was observed in the lower-energy Q-band region for calculations that made use of range-separated hybrids for both full and simplified TD-DFT approaches. The CAMB3LYP functional provided particularly accurate results in the context of the sTD-DFT approach. The description of the higherenergy B-band region is considerably less accurate, and this demonstrates the need for further advances in the accuracy of theoretical calculations. Together with a general increase in accuracy, the application of simplified TD-DFT methods affords a 2−3 orders of magnitude speedup of the calculations in comparison to the full TD-DFT approach. It is anticipated that this approach will be widely used on desktop computers during the interpretation of UV−vis−NIR spectra of phthalocyanines and related macrocycles in the years ahead.
- Full Text:
- Authors: Martynov, Alexander G , Mack, John , May, Aviwe K , Nyokong, Tebello , Gorbunova, Yulia G , Tsivadze, Aslan Yu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186915 , vital:44547 , xlink:href="https://doi.org/10.1021/acsomega.8b03500"
- Description: A methodological survey of density functional theory (DFT) methods for the prediction of UV−visible (vis)−near-infrared (NIR) spectra of phthalocyanines is reported. Four methods, namely, full time-dependent (TD)-DFT and its Tamm−Dancoff approximation (TDA), together with their simplified modifications (sTD-DFT and sTDA, respectively), were tested by using the examples of unsubstituted and alkoxy-substituted metal-free ligands and zinc complexes. The theoretical results were compared with experimental data derived from UV−visible absorption and magnetic circular dichroism spectroscopy. Seven popular exchange-correlation functionals (BP86, B3LYP, TPSSh, M06, CAM-B3LYP, LC-BLYP, and ωB97X) were tested within these four approaches starting at a relatively modest level using 6-31G(d) basis sets and gas-phase BP86/def2-SVP optimized geometries. A gradual augmentation of the computational levels was used to identify the influence of starting geometry, solvation effects, and basis sets on the results of TD-DFT and sTD-DFT calculations. It was found that although these factors do influence the predicted energies of the vertical excitations, they do not affect the trends predicted in the spectral properties across series of structurally related substituted free bases and metallophthalocyanines. The best accuracy for the gas-phase vertical excitations was observed in the lower-energy Q-band region for calculations that made use of range-separated hybrids for both full and simplified TD-DFT approaches. The CAMB3LYP functional provided particularly accurate results in the context of the sTD-DFT approach. The description of the higherenergy B-band region is considerably less accurate, and this demonstrates the need for further advances in the accuracy of theoretical calculations. Together with a general increase in accuracy, the application of simplified TD-DFT methods affords a 2−3 orders of magnitude speedup of the calculations in comparison to the full TD-DFT approach. It is anticipated that this approach will be widely used on desktop computers during the interpretation of UV−vis−NIR spectra of phthalocyanines and related macrocycles in the years ahead.
- Full Text:
Research for the people, by the people: The political practice of cognitive justice and transformative learning in environmental social movements
- Authors: Burt, Jane C
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392177 , vital:68728 , xlink:href="https://doi.org/10.3390/su11205611"
- Description: This paper describes how Changing Practice courses, developed by environmental activists in South Africa and based on social learning practice, have seeded cognitive justice action. For the educator-activists who facilitated these courses, it became apparent that we needed a bold emancipatory pedagogy which included cognitive justice issues. This enabled us and the activist-researcher participants to understand the extent to which local, indigenous, and spiritual knowledge had been excluded from water governance. The paper investigates how participants in the ‘Water and Tradition’ change project, established by the Vaal Environmental Justice Alliance (VEJA, engaged with cognitive justice, to demonstrate how African spiritual practice offers a re-visioning of the natural world. Finally, using the tools of critical realist theory, the paper reviews how VEJA bring about transformative social action through their participation in the Changing Practice course.
- Full Text:
- Authors: Burt, Jane C
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392177 , vital:68728 , xlink:href="https://doi.org/10.3390/su11205611"
- Description: This paper describes how Changing Practice courses, developed by environmental activists in South Africa and based on social learning practice, have seeded cognitive justice action. For the educator-activists who facilitated these courses, it became apparent that we needed a bold emancipatory pedagogy which included cognitive justice issues. This enabled us and the activist-researcher participants to understand the extent to which local, indigenous, and spiritual knowledge had been excluded from water governance. The paper investigates how participants in the ‘Water and Tradition’ change project, established by the Vaal Environmental Justice Alliance (VEJA, engaged with cognitive justice, to demonstrate how African spiritual practice offers a re-visioning of the natural world. Finally, using the tools of critical realist theory, the paper reviews how VEJA bring about transformative social action through their participation in the Changing Practice course.
- Full Text:
Stability indicating HPLC-ECD method for the analysis of clarithromycin in pharmaceutical dosage forms: Method scaling versus re-validation.
- Makoni, Pedzisai A, Chikukwa, Mellisa T R, Khamanga, Sandile M, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Chikukwa, Mellisa T R , Khamanga, Sandile M , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183387 , vital:43984 , xlink:href="https://doi.org/10.3390/scipharm87040031"
- Description: An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.
- Full Text:
- Authors: Makoni, Pedzisai A , Chikukwa, Mellisa T R , Khamanga, Sandile M , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183387 , vital:43984 , xlink:href="https://doi.org/10.3390/scipharm87040031"
- Description: An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.
- Full Text:
- «
- ‹
- 1
- ›
- »