Critical realism, environmental learning and social-ecological change
- Authors: Price, Leigh , Lotz-Sisitka, Heila
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/436952 , vital:73319 , ISBN 9781315660899 , https://www.routledge.com/Critical-Realism-Environmental-Learning-and-Social-Ecological-Change/Price-Lotz-Sistka/p/book/9780367597689
- Description: The contemporary social-ecological condition is characterized by power-ful changes in the way that we relate to each other and to the environ-ment. This has led to increased ecological vulnerability, which is also ac-companied by ongoing, and increased societal vulnerability. Nevertheless there remain opportunities for developing new social-ecological rela-tions, and for social-ecological learning and change. This would seem to require a strong project of recovering ontology, and a challenging and broadening of dominant ways of knowing (Mignolo, 2000) that also tend to commit what Bhaskar describes as the ‘epistemic fallacy’, or the ‘the analysis or reduction of being to knowledge of being’ (Bhaskar, 2010, p. 1). In response, Bhaskar (ibid.) suggests critical realism as an alternative that embodies a ‘compatibility of ontological realism, epistemological relativism and judgmental rationality’. This includes a ‘re-vindication of ontology’ and the possibility of recognizing and accounting for structure, difference and change in the world in ways that escape ontological actu-alism and ontological monovalence or ‘the generation of a purely positive account of reality’ (ibid., p. 15).
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- Date Issued: 2015
DDoS Attack Mitigation Through Control of Inherent Charge Decay of Memory Implementations
- Authors: Herbert, Alan , Irwin, Barry V W , van Heerden, Renier P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430339 , vital:72684 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: DDoS (Distributed Denial of Service) attacks over recent years have shown to be devastating on the target systems and services made publicly available over the Internet. Furthermore, the backscatter1 caused by DDoS attacks also affects the available bandwidth and responsiveness of many other hosts within the Internet. The unfortunate reality of these attacks is that the targeted party cannot fight back due to the presence of botnets and malware-driven hosts. These hosts that carry out the attack on a target are usually controlled remotely and the owner of the device is unaware of it; for this reason one cannot attack back directly as this will serve little more than to disable an innocent party. A proposed solution to these DDoS attacks is to identify a potential attacking address and ignore communication from that address for a set period of time through time stamping.
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- Date Issued: 2015
Density and regrowth of a forest restio (Ischyrolepis eleocharis) under harvest and non-harvest treatments in dune forests of Eastern Cape Province, South Africa
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180828 , vital:43649 , xlink:href="https://doi.org/10.1007/s12231-015-9306-y"
- Description: Ischyrolepis eleocharis (Mast.) H.P.Linder is a perennial rush or sedge-like herb in the Restionaceae family and has been harvested for various uses from coastal forest dunes of South Africa. Around 2005, a ban on I. eleocharis harvesting in Bathurst coastal forest was instituted by provincial conservation authorities based on their unsubstantiated impression that the species population was decreasing. Here we report on the population density pre and post the harvest ban, as well as further explore the autecology of the species by assessing plant density relative to environmental factors (slope and aspect) and a controlled experiment on regrowth after harvesting at different intensities. The results show that the shoot density of both living and dead I. eleocharis increased significantly over the past eight years. This concurs with results from the harvesting experiment which showed that I. eleocharis recovered rapidly within a year of harvesting. Both aspect and slope play a key role in the distribution of I. eleocharis, with most plants found in open patches in the forest located on the summit and upper slopes of dunes facing the landward side. These results indicate that I. eleocharis is highly abundant and resilient to harvesting.
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- Date Issued: 2015
Dialectical critical realism and cultural historical activity theory (CHAT): Exploring and expanding learning processes in sustainable agriculture workplace contexts
- Authors: Mukute, Mutizwa
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436996 , vital:73322 , ISBN 9781315660899 , https://www.routledge.com/Critical-Realism-Environmental-Learning-and-Social-Ecological-Change/Price-Lotz-Sistka/p/book/9780367597689
- Description: Sustainable agriculture (its learning, practice and development) is becoming increasingly important in Africa and globally be-cause of its potential to reduce social ecological risks while simultaneously enhancing related sustainability and resilience. Against this background, the objectives of the study forming the basis of this chapter were to explore and expand the learn-ing and practice of sustainable agriculture in three research sites in southern Africa. This paper focuses on how the author worked with critical realism to underlabour Cultural Historical Activity Theory (CHAT) to address the research objectives. Us-ing a multiple case study approach, the author worked with 80 farmers, extension workers, sustainable agriculture facilitators and researchers and organic marketers to explore and expand their learning and practice of three kinds of sustainable agricul-ture: permaculture, organic farming and the Machobane Farm-ing System (MFS). In particular the author made use of critical realism’s dialectics, multiple layers of reality and causal expla-nation, double hermeneutics, and modes of inference to deep-en data generation, analysis and use. Working with critical real-ism enabled the study to: (a) pay attention to causal mecha-nisms and power relations; (b) provide explanatory critique; (c) achieve in-depth ‘exploration’ through inductive, abductive and retroductive analysis; and (d) overcome the constructivist limi-tations of CHAT. Critical realism also enabled the mobilization of research participants’ agency and reflexivity to respond to the socio-ecological issues and risks that they were facing. The author concluded that critical realism can be effectively used to underlabour constructivist and epistemological theo-ries for ontological depth; and to help understand and tackle contemporary social ecological issues.
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- Date Issued: 2015
DNA-based identification of Lepidoptera associated with citrus in South Africa
- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, A E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
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- Date Issued: 2015
Ecological sustainability for non-timber forest products: dynamics and case studies of harvesting
- Authors: Shackleton, Charlie M , Pandey, Ashok K , Ticktin, Tamara
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/433656 , vital:72992 , ISBN 9781317916130 , https://www.routledge.com/Ecological-Sustainability-for-Non-timber-Forest-Products-Dynamics-and-Case/Shackleton-Pandey-Ticktin/p/book/9781138618251
- Description: There is growing knowledge about and appreciation of the im-portance of Non-timber Forest Products (NTFPs) to rural liveli-hoods in developing countries, and to a lesser extent, devel-oped countries. However, there is also an assumption on the part of policy-makers that any harvesting of wild animal or plant products from the forests and other natural and modi-fied ecosystems must be detrimental to the long-term viability of target populations and species. This book challenges this idea and shows that while examples of such negative impacts certainly exist, there are also many examples of sustainable harvesting systems for NTFPs. The chapters review and pre-sent coherent and scientifically sound information and case studies on the ecologically sustainable use of NTFPs. They also outline a general interdisciplinary approach for assessing the sustainability of NTFP harvesting systems at different scales. A wide range of case studies is included from Africa, Asia and South America, using plant and animal products for food, crafts, textiles, medicines and cosmetics.
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- Date Issued: 2015
Ecologically sustainable harvesting of non-timber forest products: Disarming the narrative and the complexity
- Authors: Shackleton, Charlie M , Pandey, Ashok K , Ticktin, Tamara
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433670 , vital:72993 , ISBN 9781317916130 , https://www.routledge.com/Ecological-Sustainability-for-Non-timber-Forest-Products-Dynamics-and-Case/Shackleton-Pandey-Ticktin/p/book/9781138618251
- Description: As introduced at the outset of this book, the need for ecologically sustainable harvesting systems for tens of thousands of non-timber forest products (NTFPs) around the world is a requirement for the conservation of the species concerned, and the lives, livelihoods and economies that depend on those species. Ecological sustainability is not simply a ‘nice to have’, a marketing ploy or a conservation fad. Unsustainable harvesting leads to the decline, sooner or later, of NTFP gene pools, populations and species and hence the livelihoods, and species and ecosystem services dependent upon them. Often the negative impacts on peoples’ lives and incomes are not immediately apparent because they may substitute the diminishing returns from one species by harvesting another species, such as favoured firewood species for less preferred species (Madubansi and Shackleton 2007). However, the second, third or more substitute yields lower returns in quality or quantity (or both) than the most preferred species and so a trajectory of dwindling returns looms, either of the benefits obtained, or increased costs to access the benefits. On the other hand, the concept of an ecologically sustainable yield is relatively easy to grasp (Ticktin Chapter 3). All biological resources are renewable. If the rate of harvest is less than the rate of renewal, then the NTFP species or population should persist in the long term. This simplistic picture needs to be fine-tuned to ensure that there are no exacerbatory or synergistic impacts associated with the direct effects of harvesting (such as changes in browsing patterns or fire behaviour)(Ticktin and Shackleton 2011, Ticktin Chapter 3). Additionally, the effects at broader scales, ie beyond just the target species, need to be also taken into account, such as on pollinators, decomposers, nutrient cycles and the like (Ticktin 2004). But in principle, the definition and measurement of an ecologically sustainable yield is well within the means of modern science for the majority of plant and animal NTFP species.
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- Date Issued: 2015
Editorial. Perspectives on transformations in learning and education
- Authors: Lotz-Sisitka, Heila
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387277 , vital:68221 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137656"
- Description: Perspectives on transformations in learning and education
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- Date Issued: 2015
Effects of differently shaped silver nanoparticles on the photophysics of pyridylsulfanyl-substituted phthalocyanines
- Authors: D'Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193564 , vital:45348 , xlink:href="https://doi.org/10.1016/j.poly.2015.06.038"
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines.
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- Date Issued: 2015
Effects of ZnO nanohexagons and nanorods on the fluorescence behavior of metallophthalocyanines
- Authors: D'Souza, Sarah , Moeno, Sharon , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189741 , vital:44927 , xlink:href="https://doi.org/10.1016/j.poly.2014.09.012"
- Description: This paper looks at the fluorescence behavior of zinc phthalocyanines: 2,(3),9(10),16(17),23(24)-tetrakis- (mercaptoacetic acid phthalocyaninato) zinc(II) (ZnTMAAPc), 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptopropanoic acid phthalocyaninato) zinc(II) (ZnTMPAPc) and (OH)AlPcSmix (the latter contains a mixture of the di-, tri- and tetra-sulfonated derivatives with an average of three sulfonated groups per molecule) in the presence of ZnO nanoparticles. Fluorescence lifetimes of Pc complexes generally decreased in the presence of ZnO nanoparticles, with generally longer lifetimes for ZnO nanohexagons compared to ZnO nanorods.
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- Date Issued: 2015
Electrocatalytic activity of bimetallic Au–Pd nanoparticles in the presence of cobalt tetraaminophthalocyanine
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189719 , vital:44925 , xlink:href="https://doi.org/10.1016/j.jcis.2014.10.056"
- Description: Au and Pd nanoparticles were individually or together electrodeposited on top of polymerized cobalt tetraaminophthalocyanine (poly-CoTAPc). When Pd and Au nanoparticles are co-deposited together, the electrode is denoted as Au–Pd (co-deposited)/poly-CoTAPc-GCE. X-ray photoelectron spectroscopy (XPS) was used to show the successful deposition of AuNPs, PdNPs and Au–Pd (co-deposited). The scanning electrochemical microscopy showed that Au–Pd (co-deposited)/poly-CoTAPc-GCE (with current range of 9.5–13.5 lA) was more conducting than Au–Pd (co-deposited)-GCE (with current range of 8–12 lA). Electrochemical impedance spectroscopy (EIS) showed that there was less resistance to charge transfer for Au–Pd (co-deposited)/poly-CoTAPc-GCE compared to the rest of the electrodes. Au–Pd (co-deposited)/poly-CoTAPc-GCE showed the best activity for the electrooxidation of hydrazine in terms of limit of detection (0.5 lM), hence shows promise as an electrocatalyst for electrooxidation of hydrazine.
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- Date Issued: 2015
Electrocatalytic studies of covalently immobilized metal tetra-amino phthalocyanines onto derivatized screen-printed gold electrodes
- Authors: Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249059 , vital:51774 , xlink:href="https://doi.org/10.1007/s00604-010-0438-6"
- Description: Metal tetra-amino phthalocyanine complexes (MTAPc; where M is Co or Mn) were immobilized on screen-printed gold electrodes pre-modified with monolayers of benzylamino groups. The functionalized electrodes were then activated using benzene-1,4-dicarbaldehyde as a linker before MTAPc complexes were immobilized. The surface coverages for the modified electrodes confirmed the perpendicular orientation of the MTAPcs. The apparent electron transfer constant (kapp) for the electrodes is 2.2 × 10−5 cm.s−1 for both CoTAPc and MnTAPc modified electrodes as calculated with data from impedance measurements. The kapp values for the bare and benzylamino modified electrodes were found to be 1.2 × 10−4 cm.s−1 and 4.9 × 10−6 cm.s−1, respectively. The electrocatalysis of the modified electrodes towards detection of H2O2 gave significant peak current densities and electrocatalytic potentials at −0.28 V and −0.31 V for the MnTAPc and CoTAPc modified electrodes, respectively.
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- Date Issued: 2015
Electrode modification using alkynyl substituted Fe (II) phthalocyanine via electrografting and click chemistry for electrocatalysis
- Authors: Nxele, Siphesihle R , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189296 , vital:44835 , xlink:href="https://doi.org/10.1002/elan.201500212"
- Description: In this work, tetrakis(5-hexyn-oxy)Fe(II) phthalocyanine was synthesised in order to perform a click reaction between the terminal alkyne groups and an azide group on a glassy carbon electrode (GCE) surface. An azide group was formed on the electrode surface following electrografting using 4-azidobenzene diazonium tetrafluoroborate by electrochemical reduction. The Cu(I) catalyzed alkyne-azide Huisgen cycloaddition reaction was then employed in order to react the terminal alkyne groups on the phthalocyanine with the azide groups on the GCE surface. The modified electrode was employed to catalyse the oxidation of hydrazine. The electrode showed good electrocatalytic ability towards the detection of hydrazine with a sensitivity of 15.38 µA mM−1 and a limit of detection of 1.09 µM.
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- Date Issued: 2015
Enhanced optical limiting behaviour of indium phthalocyanine derivatives when in solution or embedded in poly (acrylic acid) or poly (methyl methacrylate) polymers
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189445 , vital:44847 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.02.003"
- Description: The optical limiting performance of indium phthalocyanine-based polymer thin-films with large nonlinear absorption coefficients (βeff) and low limiting threshold intensity (Ilim) are described. The absorption cross-sections and the population dynamics of the excited states are also reported. The excited state absorption cross-sections (σexc) are shown to depend on the transition moment between the T1 and T2 states. βeff values have been shown to be related to the population density of the molecules in the T1 state. The improved optical limiting performance recorded for the investigated phthalocyanine complexes in the presence of polymer matrices has been attributed to the aggregation effects of the complexes in the polymer thin-films. The optical properties of the indium phthalocyanine moieties were found to possess robust sensitivity to a change of the polymer materials.
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- Date Issued: 2015
Enhanced triplet state parameters for zinc carboxy phenoxy phthalocyanine following conjugation to ascorbic acid
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189348 , vital:44839 , xlink:href="https://doi.org/10.1016/j.poly.2015.01.032"
- Description: Zinc phthalocyanine bearing four ascorbic acid units (formed via ester bond between zinc carboxy phenoxy phthalocyanines and ascorbic acid) was synthesized and characterized using different spectroscopic methods. The complex (with or without ascorbic acid) was further adsorbed onto single walled carbon nanotubes (SWCNTs) and further characterized using Raman spectroscopy, X-ray diffractometry, transmission electron microscopy and thermogravimetric analysis. The photophysical properties of the complexes were studied. The synthesized complex showed better photophysical properties when compared to the carboxy phenoxy phthalocyanines alone, this is evident in the increase of the triplet quantum yields (ΦT), triplet life-times (τT) and singlet oxygen quantum yields (ΦΔ). The zinc phthalocyanines bearing ascorbic acid showed improved triplet life-times even in the presence of SWCNTs.
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- Date Issued: 2015
Enhanced triplet state yields in aqueous media of asymmetric zinc phthalocyanines when conjugated to silver nanoflowers
- Authors: D'Souza, Sarah , George, Reama , Göksel, Meltem , Atilla, Devrim , Durmus, Mahmut , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189099 , vital:44816 , xlink:href="https://doi.org/10.1016/j.poly.2015.08.017"
- Description: Novel low symmetry water-soluble zinc phthalocyanines (ZnPcs, complexes 1 and 2) were synthesized and then mixed with silver nanoflowers. Photophysical and photochemical studies were performed in order to determine the efficiency of complexes 1 and 2 as photosensitizers when alone and when combined with the silver nanoflowers. The Pcs show low fluorescence quantum yields and excellent triplet quantum yields of 0.78 (for 1) and 0.66 (for 2) in aqueous media. The triplet quantum yield values increased to 0.80 and 0.89, respectively, in the presence of silver nanoflowers. Long triplet lifetimes ranging from 180 to 200 μs in DMSO were obtained for complexes 1, 2 and their conjugates with silver nanoflowers.
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- Date Issued: 2015
Enhancing cloud connectivity among NRENs in the SADC region through a novel institution cloud infrastructure framework
- Authors: Suresh, Nalina , Mbale, Jameson , Terzoli, Alfredo , Mufeti, Tulimevava K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430592 , vital:72702 , 10.1109/ETNCC.2015.7184830
- Description: It is increasingly being recognized that faster socioeconomic develop-ment in Africa is dependent upon the development of Information and Communication Technology (ICT) Infrastructure for the dissemination of data and educational services. The scalability and flexibility provided by Cloud services in terms of resource management, service provisioning and virtualization makes it an attractive system for use with educational and ICT services. The flexibility of pay-as-you-go models combined with the ability to scale computing, storage and/or networking resources makes Cloud computing an ideal candidate for use with education, re-search and scientific infrastructures. Notwithstanding its benefits, transi-tioning from a traditional IT infrastructure to a Cloud computing para-digm raises security concerns with respect to data storage, data trans-mission and user privacy. This paper presents on-going research for the development of Science, Technology and Innovation (STI) infra-structure for the distribution of Information Communication technologies (ICT) services in the African context. The Inter-Cloud Infrastructure Framework (ICIF) proposed, is conceived as a Cloud computing framework suitable for use with National Research and Education Net-works (NRENs) in the SADC region. The ICIF system is used to create an Inter-Cloud infrastructure, and helps NRENs transition from tradi-tional IT infrastructure systems to the Cloud computing paradigm. It also provides new functional/operational components and Cloud services to support the interconnection and/or interoperability among SADC NRENs through the ICIF infrastructure.
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- Date Issued: 2015
Exploring contradictions and absences in mobilizing ‘learning as process' for sustainable agricultural practices
- Authors: Pesanayi, Tichaona
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437008 , vital:73323 , ISBN 9781315660899 , https://www.routledge.com/Critical-Realism-Environmental-Learning-and-Social-Ecological-Change/Price-Lotz-Sistka/p/book/9780367597689
- Description: Water is a fascinating, life-giving being. It flows. It cuts into the earth to create its passage by finding the places where the earth will give. As it meanders it passes through many different contexts, whether at a fastrush-full-blown flood or the trickle of an underground desert stream. It does not demand that the space it moves through is homogenous. It adapts to whatever terrain it finds itself journeying through. Human creatures, dependent as they are on water for their own beings and for life, flock to water like flies to food. We build our cities, our factories and homes on the banks and corners of rivers and draw and drink and use (and abuse) water. We throw in and we take out and the river keeps going until sometimes it doesn’t. Then we worry. Sometimes it is not the lack of flow that worries us but the fact that when we drink it babies become sick, some die and this causes a stir. In South Africa this security, or lack of it, is embedded in the political historical landscape of this land. Water is classified as scarce. Our rainfall is low in comparison to other countries. In South Africa, during apartheid this scarce resource was not avail able in equal measure to all. The rulers of apartheid South Africa were farmers and miners. They were of British decent, sent to farm the new colony. They were also descended from first colonial settlers arriving from the Nether-lands and then Germany, known colloquially as the Boers. South Africa was divided and redivided until in 1948 the Boers gained independence from British rule and finished the job that the British had started by legalizing the separation of races. Farming was still core to the Boer way of life and this is reflect-ed in the laws that dictated resource use and management, such as the 1956 Water Act No. 54 (RSA, 1956) which gave riparian rights to those that owned land. Water was also subsi-dized to boost the economy, particularly for the large mines, and parastatals such as Eskom (Byrnes, 1996). Water was not only used to ensure that the economy of white South Africa flourished, it also was the landmark of division.
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- Date Issued: 2015
Facile synthesis, spectroscopic and electrochemical properties, and theoretical calculations of porphyrin dimers with a bridging amide-bonded xanthene moiety
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241390 , vital:50935 , xlink:href="https://doi.org/10.1142/S1088424615500492"
- Description: A free base porphyrin dimer bridged by a flexible amide-bonded xanthene moiety and its binuclear zinc(II) complex zinc(II) complex were synthesized and characterized. Structural characterization by MS and 1H NMR spectroscopy confirmed the bridged porphyrin dimer structure. The properties of the dimers were characterized by IR, UV-visible absorption, fluorescence and magnetic circular dichroism (MCD) spectroscopy, and electrochemistry studies. Theoretical calculations were carried out to analyze the electronic structures of porphyrin dimers with a bridging amide-bonded xanthene moiety.
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- Date Issued: 2015
Fluorescence behavior and singlet oxygen generating abilities of aluminum phthalocyanine in the presence of anisotropic gold nanoparticles
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193598 , vital:45351 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
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- Date Issued: 2015