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.
- Full Text:
- Date Issued: 2015
'I won't be squeezed into someone else's frame': Stories of supervisor selection
- Authors: Harrison, Liz , McKenna, Sioux , Searle, Ruth
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187395 , vital:44629 , xlink:href="https://hdl.handle.net/10520/EJC15100"
- Description: Using a collection of stories from a group of women who belong to a PhD support group, this article tracks the issue of choosing a supervisor. These women are all academics and therefore had some claim to an "insider" status but as novice researchers they were also "outsiders". Their discussions around how and why they chose their supervisors highlight issues often underplayed or ignored in textbooks on postgraduate supervision. In particular, this article examines issues of knowledge, embodied subjectivity and power by following three questions that arise from the data : whose knowing is important; who should I be, and whose PhD is it?
- Full Text:
- Date Issued: 2010
Applications of polymerized metal tetra-amino phthalocyanines towards hydrogen peroxide detection
- Authors: Mashazi, Philani N , Togo, Chumunorwa , Limson, Janice L , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261840 , vital:53451 , xlink:href="https://doi.org/10.1142/S1088424610001994"
- Description: This work reports the use of metallo tetra-amino phthalocyanines (MTAPc, M = Co and Mn) polymer thin films on gold and glassy carbon electrode surfaces for the detection and monitoring of hydrogen peroxide (H2O2). The polymer-modified electrodes were characterized using electrochemical and microscopic-based methods. Atomic force microscopy (AFM) was used to study the bare and polymer-modified ITO surfaces. The electrocatalytic reduction of H2O2 with glassy carbon polymer-modified electrodes gave higher current densities compared to their gold counterparts. The electroanalytical properties of H2O2 were obtained using a real-time calibration curve of the amperometric determination in pH 7.4 aqueous solution. The limits of detection (LoD) of the polymer-modified electrodes towards electroreduction of H2O2 were of the order of 10–7 M, with high sensitivity ranging from 6.0–15.4 mA.mM-1.cm-2.
- Full Text:
- Date Issued: 2010
Art and Ethical Criticism, edited by Garry L. Hagberg
- Authors: Jones, Ward E
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275612 , vital:55063 , xlink:href="https://doi.org/10.1093/mind/fzq098"
- Description: Book Review: If there is a norm that a book’s title should give a reliable indication of its contents, Art and Ethical Criticism does not quite meet it. By my judgement, only seven of its twelve essays concern either the ethical criticism of art or the criticism of ethical positions within artworks.
- Full Text:
- Date Issued: 2010
at the conference in munich
- Authors: Krueger, Anton
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229774 , vital:49709 , xlink:href="https://hdl.handle.net/10520/EJC47821"
- Full Text:
- Date Issued: 2010
Biodiversity research and conservation: careers
- Authors: Rosenberg, Eureta
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391079 , vital:68615 , xlink:href="https://hdl.handle.net/10520/EJC89811"
- Description: It is the International Year of Biodiversity, and if you are interested in a career in biodiversity, there are many options from which to choose. This article introduces the dynamic and growing field of biodiversity management, research and conservation. It gives a taste of the varied careers that would suit different interests and talents and invites you to look with fresh eyes at the field and its possibilities.
- Full Text: false
- Date Issued: 2010
Changing social imaginaries, multiplicities and ‘one sole world’: Reading Scandinavian environmental and sustainability education research papers with Badiou and Taylor at hand
- Authors: Lotz-Sisitka, Heila
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182506 , vital:43836 , xlink:href="https://doi.org/10.1080/13504620903504081"
- Description: Badiou’s ontological work draws attention to multiplicities – the oneness of ontology, which he explains can only become ontologically differentiated into events or sites through political, artistic or amorous practices that philosophies can think and invent from. He also draws attention to the fusion of events and sites, and he explains that events (such as producing special issues of journals located in particular sites) are reflexive. He also tells us, however, that the reflexive structure of an artistic or scientific event (such as producing a special issue of a journal) is not always immediately evident. In writing this response article I work with this concept – and probe how the production of events (such as a special issue of a journal produced in a specific site) may be reflexive. This is the purpose of the article. This response article therefore probes some of the political, structural and intellectual processes that come to shape scholarship in different sites, and here I draw on the insights into social imaginaries provided by Charles Taylor to develop a perspective on the scholarship that is reflected in this journal. Through this, I seek to open the notion of multiplicities, oneness and the particularities of our social imaginaries as themes for thinking about educational scholarship events produced within and across geo‐physical, socio‐ecological and socio‐economic spaces in different parts of the world.
- Full Text:
- Date Issued: 2010
Climate injustice: How should education respond?
- Authors: Lotz-Sisitka, Heila
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437268 , vital:73364 , ISBN 9780203866399 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780203866399-11/climate-injustice-education-respond-heila-lotz-sisitka
- Description: The Fourth Assessment Report of the Intergovernmental Panel on Cli-mate Change (IPCC 2007) identifi es Africa as one of the continents of the world most vulnerable to climate change. Africa’s vulnerability to climate change is aggravated by the interaction of multiple stresses such as poverty, poor governance, and weak institutions, limited access to capi-tal (including technology), ecosystem degradation, confl ict and disasters (UNEP 2006), and a generally poor quality of education (UNESCO 2004). The climate injustices and exacerbating circumstances experienced by poor and weak states today lie in the long-term historical emergence of a modern (and increasingly global) world order framed by a hegemonic Westphalian state system. This state system privileges exclusive, undi-vided sovereignty over a bounded territory (Fraser 2008), and is known more popularly as the ‘nation state’ system.
- Full Text:
- Date Issued: 2010
Data classification for artificial intelligence construct training to aid in network incident identification using network telescope data
- Authors: Cowie, Bradley , Irwin, Barry V W
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430125 , vital:72667 , https://doi.org/10.1145/1899503.1899544
- Description: This paper considers the complexities involved in obtaining training da-ta for use by artificial intelligence constructs to identify potential network incidents using passive network telescope data. While a large amount of data obtained from network telescopes exists, this data is not current-ly marked for known incidents. Problems related to this marking process include the accuracy of the markings, the validity of the original data and the time involved. In an attempt to solve these issues two methods of training data generation are considered namely; manual identification and automated generation. The manual technique considers heuristics for finding network incidents while the automated technique considers building simulated data sets using existing models of virus propagation and malicious activity. An example artificial intelligence system is then constructed using these marked datasets.
- Full Text:
- Date Issued: 2010
Development of an IMS Compliant, Cross Platform Client Using the JAIN SIP Applet Phone
- Authors: Muswera, Walter T , Terzoli, Alfredo
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431274 , vital:72760 , https://www.cs.ru.ac.za/research/g09M3278/Muswera.pdf
- Description: Several open source SIP/IMS Clients are currently in use in the Rhodes University Convergence Research Group. However, there is no single Client that provides researchers with all the required functionality need-ed to test the applications they have developed. Integrating advanced features into a single Client can help to speed up testing as well as pro-vide a variety of innovative communication services. In this paper we present an overview of two popular SIP/IMS Clients currently in use. We also discuss the features and design architecture of a Client called JAIN SIP Applet Phone (JSAP) which will be used as a basis for the development of a new IMS compliant Client. We then analyse what functionality JSAP lacks and propose features that need to be imple-mented.
- Full Text:
- Date Issued: 2010
Ecological impacts of small dams on South African rivers Part 1: Drivers of change–water quantity and quality
- Authors: Mantel, Sukhmani K , Hughes, Denis A , Muller, Nikite W J
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438099 , vital:73435 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2398.pdf
- Description: Impacts of large dams are well-known and quantifiable, while small dams have generally been perceived as benign, both socially and envi-ronmentally. The present study quantifies the cumulative impacts of small dams on the water quality (physico-chemistry and invertebrate biotic indices) and quantity (discharge) of downstream rivers in 2 South African regions. The information from 2 South African national data-bases was used for evaluating the cumulative impacts on water quality and quantity. Physico-chemistry and biological data were obtained from the River Health Programme, and discharge data at stream flow gauges was obtained from the Hydrological Information System. Multivariate analyses were conducted to establish broad patterns for cumulative impacts of small dams across the 2 regions–Western Cape (winter rain-fall, temperate, south-western coast) and Mpumalanga (summer rain-fall, tropical, eastern coast). Multivariate analyses found that the chang-es in macroinvertebrate indices and the stream’s physico-chemistry were more strongly correlated with the density of small dams in the catchment (as a measure of cumulative impact potential) relative to the storage capacity of large dams. T-tests on the data, not including sam-ples with upstream large dams, indicated that the high density of small dams significantly reduced low flows and increased certain physico-chemistry variables (particularly total dissolved salts) in both the re-gions, along with associated significant reductions in a macroinverte-brate index (SASS4 average score per taxon). Regional differences were apparent in the results for discharge reductions and the macroin-vertebrate index. The results suggest that the cumulative effect of a high number of small dams is impacting the quality and quantity of wa-ters in South African rivers and that these impacts need to be systemat-ically incorporated into the monitoring protocol of the environmental wa-ter requirements.
- Full Text:
- Date Issued: 2010
Ecological impacts of small dams on South African rivers Part 2: Biotic response–abundance and composition of macroinvertebrate communities
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438087 , vital:73434 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2354.pdf
- Description: This paper investigates the cumulative impacts of small dams on inver-tebrate communities in 2 regions of South Africa–the Western Cape and Mpumalanga. Previous research found reduced discharge, in-creased total dissolved salts, and a decrease in average score per tax-on (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigat-ed using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catch-ment in foothill-gravel streams (in both Western Cape and Mpuma-langa) and in foothill-cobble streams (in Western Cape only). Opportun-istic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and sea-sons) and detailed (at species level) collection of data to verify the re-sults of cumulative effects of small dams. This can further the devel-opment of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
- Date Issued: 2010
Electrocatalytic oxidation of amitrole and diuron on iron (II) tetraaminophthalocyanine-single walled carbon nanotube dendrimer
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262611 , vital:53536 , xlink:href="https://doi.org/10.1016/j.electacta.2009.12.051"
- Description: FeTAPc-single walled carbon nanotube (SWCNT) dendrimers are employed as glassy carbon electrode modifiers for the electrocatalytic oxidations of amitrole and diuron. The catalytic rate constants were 4.55 × 103 M−1 s−1 and 1.79 × 104 M−1 s−1 for amitrole and diuron, respectively using chronoamperometric studies. The diffusion constants were found to be 1.52 × 10−4 cm2 s−1 and 1.91 × 10−4 cm2 s−1 for diuron and amitrole, respectively. The linear concentration range for both were from 5.0 × 10−5 to 1.0 × 10−4 M and sensitivities of 0.6603 μA/μM and 0.6641 μA/μM for amitrole and diuron, with corresponding limits of detection of 2.15 × 10−7 and 2.6 × 10−7 M using the 3δ notation, respectively.
- Full Text:
- Date Issued: 2010
Electrochemical, spectroscopic and microscopic studies of new manganese phthalocyanine complexes in solution and as self-assembled monolayers on gold
- Authors: Coates, Megan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261144 , vital:53363 , xlink:href="https://doi.org/10.1142/S1088424610002471"
- Description: Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
- Full Text:
- Date Issued: 2010
Ethics-oriented learning in environmental education workplaces: An activity theory approach
- Authors: Olvitt, Lausanne L
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370961 , vital:66398 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122874"
- Description: In the context of increasing national and global environmental challenges and their implications for the working world, new ethics and practices are being introduced into workplaces that take better account of socio-ecological relations. Little is understood, however, about the nature of ethics-oriented workplace learning. Drawing on Cultural Historical Activity Theory (CHAT), which enables historically and contextually situated relational perspectives to emerge, this paper explores contradictions in the activity systems of two young environmental education learner-practitioners struggling to engage with the ethical dimensions of their professional work and the professional development course they are studying. The study focuses in particular on the environmental values and ethics component of their course – a year-long Learnership in Environmental Education, Training and Development Practices (EETDP). The paper reflects how tensions and contradictions within and between the interacting activity systems of the workplace, the course, and its regulating qualifications authority influence the teaching and learning of the environmental ethics component of the course. Ethics-oriented teaching and learning processes are found to be strongly influenced by the ‘rules’ and ‘mediating tools’ of these interacting systems, but these are often at odds with the ethical perspectives, socio-cultural context and skills of the ‘subject’ and ‘community’. These systemic contradictions can be more fully understood when their cultural and historical origins are made explicit. The analytical process has led to a more nuanced understanding of ethics-oriented teaching and learning in a workplace-based course, and has revealed several areas needing more careful research (particularly the area of environmental discourses) and the explicit and implicit language of ethics.
- Full Text:
- Date Issued: 2010
Extending Java’s communication mechanisms for multicore processors
- Authors: Wells, George C
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430526 , vital:72697 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfdoi=4068ed60c317e81dc70288cf36ff586dc057233f
- Description: With the current trend towards the increased use of multicore proces-sors, there is a growing need for simple, efficient parallel programming mechanisms. While Java has good support for multithreaded and dis-tributed application development, our research into tuple-space systems for multicore processors highlighted a gap in the concurrency facilities available in Java. This arises in the context of independent applications (running in separate virtual machines) that need to synchronise their ac-tivities or communicate with each other. There are several possible solu-tions to this problem, ranging from extensions to the language and/or runtime environment through to the use of distributed programming methods. Using the latter introduces considerable performance over-heads, and so we explored the use of the Java Native Interface in order to take advantage of the interprocess communication (IPC) facilities pro-vided by the underlying operating system. The analysis and comparison of the performance of the standard approaches and our prototype library suggest that there are real benefits to be gained by alternative ap-proaches to the provision of IPC mechanisms for independent Java programs executing on multicore systems. We hope that these findings will spur further investigation of this problem and other possible solu-tions.
- Full Text:
- Date Issued: 2010
Fabrication and characterization of single walled carbon nanotubes-iron phthalocyanine nano-composite
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262622 , vital:53537 , xlink:href="https://doi.org/10.1039/C0NJ00395F"
- Description: Nano-composite of single walled carbon nanotubes (SWCNTs) and iron phthalocyanine, peripherally tetra-substituted with diethylaminoethanethiol (complex 2), was fabricated and characterized by infra red (IR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM technique gave a convincing image of the nano-composite. Self-assembled monolayer (SAM) film of the composite (SWCNT-2-SAM) was formed on gold electrode. Its surface properties were investigated, relative to that of 2-SAM film, by cyclic voltammetry and scanning electron microscopy (SEM). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, using [Fe(CN)6]3− as redox probe, were used to investigate the dynamics of electron transport in the SWCNT-2-SAM film. Lower charge transfer resistance, RCT, of the SWCNT-2-SAM modified Au electrode, relative to that of the 2-SAM modified Au electrode, was an indication of enhanced electron transport in the presence of SWCNT. The SAM film of the nano-composite showed better electrocatalytic behaviour, relative to that of 2-SAM film, towards the oxidation of the insecticide, carbofuran. The electrode (SWCNT-2-SAM) showed good selectivity for carbofuran, in the presence of diazinon (a non-electroactive interferent) and at lower concentration of the electroactive interferents (chlorpyrifos and dichlorfos).
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- Date Issued: 2010
Facile electrocatalytic oxidation of diuron on polymerized nickel hydroxo tetraamino-phthalocyanine modified glassy carbon electrodes
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261269 , vital:53379 , xlink:href="https://doi.org/10.1016/j.talanta.2010.02.037"
- Description: The facile electro-oxidation of diuron occurred at a glassy carbon electrode (GCE) modified with polymerized nickel tetraamino-phthalocyanine (NiTAPc), containing O–Ni–O bridges represented as poly-Ni(OH)TAPc-GCE. The oxidation of diuron occurred at a potential which is 60 mV less than that of poly-NiTAPc (without O–Ni–O bridges) and was accompanied by enhanced catalytic currents. The catalytic rate constant and the diffusion constant were found to be 5.91 × 102 mol−1 L s−1 and 6.43 × 10−6 cm2 s−1, respectively. The linear concentration range of diuron was 3.0 × 10−5 to 3.5 × 10−4 mol L−1 with a limit of detection (LOD) of 3.3 × 10−7 mol L−1 (3δ notation) and a sensitivity of 12.9 A mol−1 L cm−2.
- Full Text:
- Date Issued: 2010
Fashionably ethnic
- Authors: Krueger, Anton
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229567 , vital:49688 , xlink:href="https://doi.org/10.1080/1013929X.2010.9678333"
- Description: This essay highlights a shift in South African literature towards ideals of individualism and explores some of the paradoxes inherent in the competing claims of individuality and heritage. The characters created by Greig Coetzee in Happy Natives are examined as examples of identities constructed in terms of tradition, function and indoctrination. The comic potential of these incongruent identity constructions is then elaborated by means of Henri Bergson’s description of the humour arising from an inability to adapt to changing fashions. Ultimately, appeals towards tradition and individuality begin to look like similar proposals.
- Full Text:
- Date Issued: 2010
Fluorescence quenching and energy transfer in conjugates of quantum dots with zinc and indium tetraamino phthalocyanines
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262638 , vital:53539 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.12.013"
- Description: CdTe QDs capped with mercapto propionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104 M−1. High energy transfer efficiencies were obtained in some cases (as high as 93%), due to the low donor to acceptor distances.
- Full Text:
- Date Issued: 2010