Phthalocyanines and related complexes as electrocatalysts for the detection of nitric oxide
- Authors: Nyokong, Tebello , Vilakazi, Sibulelo
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290346 , vital:56741 , xlink:href="https://doi.org/10.1016/S0039-9140(03)00356-4"
- Description: Metallophthalocyanine (MPc) and metalloporphyrin complexes as well as some metalloproteins including myoglobin, hemoglobin, cyanocobalamin and cytochrome c catalyse the detection of nitric oxide (NO). The catalytic process often involve changes in the oxidation state of the catalyst. These complexes catalyse both the reduction and oxidation of NO. MPc complexes containing electroactive central metals such as CoPc and FePc generally show better catalytic activity towards the detection of NO than complexes containing electroinacive central metals. However, the involvement of ring based redox processes was confirmed for the homogenous NO catalysis using CoPc.
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- Date Issued: 2003
Press vs. public enemy no 1: challenges areas needing work
- Authors: Berger, Guy J E Gough
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455048 , vital:75398 , https://hdl.handle.net/10520/EJC146291
- Description: Our journalism about poverty is pitiful. It's a story about the poverty of our journalism. But let's start with the not-so-bad news: unlike many other countries, we do report poverty. Also, unlike many other places, we don't blame the victims - rather, we tend to be sympathetic.
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- Date Issued: 2003
Productivity and abundance of Sclerocarya birrea subsp. caffra in and around rural settlements and protected areas of the Bushbuckridge lowveld, South Africa
- Authors: Shackleton, Charlie M , Botha, Jenny , Emanuel, P L
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181607 , vital:43751 , xlink:href="https://doi.org/10.1080/14728028.2003.9752459"
- Description: Sclerocarya birrea (A. Rich.) Hochst, subsp. caffra (Sond.) Kokwaro is a common species throughout the semi-arid savannas of southern Africa, and is sought after by rural communities. It is frequently maintained in homesteads and fields in an agroforestry situation. It has also been identified by a number of international and national institutes as a key species for domestication and commercialisation. Yet, the sustainability of the resource and local user knowledge and practices have not been considered. This study reports on the abundance and productivity of S. birrea in four rural villages and neighbouring protected areas in the Bushbuckridge lowveld of the Limpopo Province, South Africa, where its common name is marula. The density of marula stems was measured in homestead plots, arable fields and the surrounding communal rangelands of each village. Fruit production was assessed by regular counting of fruit fall from marked trees of known size. Within the villages, fruit production was monitored via local community groups. Additional monitoring of fruiting was conducted on marked trees within local protected areas. The proportion of households planting or nurturing marula trees was determined through interviews with a stratified random sample of households. The density of marula trees was significantly higher in protected areas than the neighbouring communal lands, fields or homesteads. However, the majority of trees in protected areas were small, while those in homesteads were large and mature. Density of adult fruit-bearing female trees, was similar between the protected areas and homesteads, but less in fields and communal lands. S. birrea trees were maintained in 79 % of homesteads and 58 % of fields. Mean fruit yield per tree was significantly higher from village trees (less than 17 000 fruits) than protected area trees (more than 3 500 fruits), even after accounting for differences in tree size. The fresh mass of individual fruits was also greater on village trees than on trees in protected areas. Both these characteristics suggest some degree of historical selection of the trees in the homesteads and fields. There was a positive relationship between tree size and number of fruits produced.
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- Date Issued: 2003
Realistic autonomous fish for virtual reality
- Authors: Lobb, Adele , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433398 , vital:72967 , https://doi.org/10.1145/602330.602361
- Description: We create realistic autonomous fish for Virtual Reality systems. The fish are realistic in appearance, movement and behaviour: the swimming behaviour being non-scripted, within real time rendering.The form of the fish is procedurally created. The size and shape of the form are controlled by a number of variables which are stored in a simple ASCII file. This allows efficient creation of different fish at run time.The behaviour is obtained by implementing a flocking algorithm.
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- Date Issued: 2003
Rendering optimisations for stylised sketching
- Authors: Winnemöller, Holger , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432922 , vital:72913 , https://doi.org/10.1145/602330.602353
- Description: We present work that specifically pertains to the rendering stage of stylised, non-photorealistic sketching. While a substantial body of work has been published on geometric optimisations, surface topologies, space-algorithms and natural media simulation, rendering-specific issues are rarely discussed in-depth even though they are often acknowledged. We investigate the most common stylised sketching approaches and identify possible rendering optimisations. In particular, we define uncertainty-functions, which are used to describe a human-error component, discuss how these pertain to geometric perturbation and textured silhouette sketching and explain how they can be cached to improve performance. Temporal coherence, which poses a problem for textured silhouette sketching, is addressed by means of an easily computed visibility-function. Lastly, we produce an effective yet surprisingly simple solution to seamless hatching, which commonly presents a large computational overhead, by using 3-D textures in a novel fashion. All our optimisations are cost-effective, easy to implement and work in conjunction with most existing algorithms.
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- Date Issued: 2003
Revised Schools and Sustainability Pack offers Curriculum Support
- Authors: Olvitt, Lausanne L
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389852 , vital:68489 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol24-_March-2003.pdf"
- Description: Since the mid 1990s, the School Environmental Policy and Management Plan (SEP) Pack has supported educators in developing a whole-school environmental policy. This year, Share-Net has updated the pack in line with the South African revised National Curriculum and the National Environmental Education Programme (NEEP).
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- Date Issued: 2003
Revision of the genus Xiphoscelis Burmeister 1842 (Coleoptera Scarabaeidae Cetoniinae), with description of two new species and notes on its phylogeny and ecology
- Authors: Perissinotto, Renzo , Villet, Martin H , Stobbia, P
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442293 , vital:73973 , https://doi.org/10.1080/03946975.2003.10531184
- Description: Recent field work has shown that the genus Xiphoscelis Burmeister 1842 contains at least three species. The type species is re-described, and two new species are described, based on adult morphology. The distribution of all three Xiphoscelis species is mapped, and a phylogeny is proposed for the genus. Ecological data are presented and discussed in the context of the previously-reported association of members of this genus with termites.
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- Date Issued: 2003
Riverine macroinvertebrate responses to chlorine and chlorinated sewage effluents-Acute chlorine tolerances of Baetis harrisoni (Ephemeroptera) from two rivers in KwaZulu-Natal, South Africa
- Authors: Williams, M L , Palmer, Carolyn G , Gordon, Andrew K
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437990 , vital:73427 , ISBN 0378-4738 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/WaterSA_2003_04_19.pdf
- Description: Chlorine is widely used in South African sewage treatment works, and despite its volatility is likely to have a considerable impact on riverine ecosystems. This paper considers the results of acute (96 h) toxicity responses to chlorine of riverine mayfly nymphs Baetis harrisoni col-lected from the small, relatively uncontaminated suburban Westville Stream, KwaZulu-Natal and from the more severely impacted Umbilo River, which flows through the industrial area of Pinetown, KwaZulu-Natal, South Africa.
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- Date Issued: 2003
Self-Assembled Monolayers of Cobalt and Iron Phthalocyanine Complexes on Gold Electrodes
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello , Westbroek, Philippe
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290363 , vital:56743 , xlink:href="https://doi.org/10.1002/elan.200302753"
- Description: The self-assembling of the octa(hydroxyethylthio)-metallophthalocyanine {MOHETPc (M=Co and Fe)} complexes and their similar analogues, octabutylthiometallophthalocyanine {MOBTPc (M=Co and Fe)} complexes on gold electrodes are investigated. Comparative surface voltammetric insights into their distinct self-assembling properties with respect to the passivation of Faradaic processes and surface coverages, including their solution electrochemistry, suggest different orientations and non-cleavage of their CS bonds. In the pH 2−9 range, the reversible [M(III)Pc(−2)]+ / [M(II)Pc(−2)] redox couples show potential shifts close to −59 mV / pH. The gold electrodes modified with the SAMs of these species show electrocatalytic activity towards the oxidation of thiols (L-cysteine, homocysteine and penicillamine) and thiocyanate in acidic media with detection limits in the region of 10−7–10−6 mol dm−3. These monolayers are stable and easily reproducible.
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- Date Issued: 2003
Shakespeare in the Media: Newspaper Response to Shakespeare in Post-Independence West Bengal, 1948-97, Lipika Sidkar: book review
- Authors: Wright, Laurence
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455757 , vital:75454 , https://hdl.handle.net/10520/EJC48012
- Description: Reading this book is a cultural experience in itself, from the typography and layout, to the scholarly conventions observed, the treatment of the subject matter and its arrangement. I found it fascinating, perhaps exaggeratedly so because of abysmal ignorance on my part concerning the voluminous scholarly and text-book literature on Shakespeare which has streamed from the presses of the sub-continent.
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- Date Issued: 2003
Simulation and visualization of fire using extended Lindenmayer systems
- Authors: Zaniewski, Tomasz , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433303 , vital:72960 , https://doi.org/10.1145/602330.602337
- Description: This research introduces a method of using Lindenmayer Systems to model the spreading and behavior of fire inside a factory building. The research investigates the use of L-System propagated fires for determining factors such as where the fire is most likely to spread first and how fast. It also looks at an alternative way of storing the Lindenmayer System, not in the form of a string but rather as a graph. A variation on the building and traversal process is also investigated, in which the L-System is traversed depth first instead of breadth first. Results of fire propagation are presented and we conclude that L-Systems are a suitable tool for fire propagation.
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- Date Issued: 2003
Spray Oils Beyond 2000 Sustainable Pest and Disease Management, GAC Beatie, DM Watson, ML Stevens, DJ Rae and RN Spooner-Hart (Eds.): book review
- Authors: Villet, Martin H
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442099 , vital:73955 , https://hdl.handle.net/10520/EJC32548
- Description: Spray oils gained popularity as pesticides in the 1950s but were subsequently displaced in the market by synthetic compounds. With recent trends in legislation relating to pesticide residues, interest in these oils is reviving. This saw expression in the convening of the first international conference on spray oils in Sydney, late in 1999. The proceedings of that conference form the contents of this book, which features over 70 papers. The compilers clearly feel that one of the most important contributions is a newly proposed international classification scheme for spray oils, including explicit chemical standards and a common nomenclature, which is aimed at overcoming the existing ambiguous and dialectal system. However, the volume will have relevance to a much wider audience because it provides a broad overview of research into this neglected form of crop protection.
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- Date Issued: 2003
Structure and cytology of the testes of Labeo victorianus (Pisces: Cyprinidae)
- Authors: Rutaisire, Justice , Muwazi, Ruth T , Booth, Anthony J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446798 , vital:74561 , https://doi.org/10.1080/15627020.2003.11657199
- Description: Testes macromorphology and histomorphology together with sperm cytology are described for a potamodrometic cyprinid fish, Labeo victorianus, from Lake Victoria. Testes were found to be paired and elongate, suspended by a mesorchium on either side of the swim bladder. A sperm duct ran along the medial surface of each testis before fusing caudally to form the common sperm duct that terminated at the urogenital pore. Main sperm ducts were lined by simple columnar epithelium supported by a wall with elastic connective tissue and a few smooth muscle cells. The tunica albuginea divided the testes into lobules, which contained spermatogenetic cell types. The lobules, released spermatozoa into an anastomosing tubule network that emptied directly into the main sperm duct. Valve like structures were present along the length of the sperm duct and are proposed to regulate milt flow. Three types of somatic cells were observed at the onset of gonadal recrudescence; plasma and intralobular somatic cells were within the lobules, while Leydig cells were close to the blood vessels in the interstitium. Maturing testes were characterized by the dominance of spermatocytes and spermatids, both contained in cysts. Spermatozoa, arising from the spermatids, filled the lobular lumen in mature testes after spermatocyst rupture. In post spawned testes, Type A spermatogonia dominated. Testicular regression was not characterized by spermatozoa phagocytosis, rather via apoptosis.
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- Date Issued: 2003
Synthesis, spectral and electrochemical properties of a new family of pyrrole substituted cobalt, iron, manganese, nickel and zinc phthalocyanine complexes
- Authors: Obirai, Joe , Rodrigues, Nazaré Pereira , Bedioui, Fethi , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304852 , vital:58496 , xlink:href="https://0-doi.org.wam.seals.ac.za/10.1142/S1088424603000641"
- Description: A new family of pyrrole substituted metallophthalocyanine complexes, namely cobalt(II), iron(II), manganese(III), nickel(II) and zinc(II) tetrakis-4-(pyrrol-1-yl)phenoxy phthalocyanines (noted as M(TPhPyrPc), where M is the metallic cation) have been synthesized and fully characterized. In particular, the UV-visible spectra of the iron and nickel complexes showed extensive aggregation even at low concentrations. The cyclic voltammetry of the cobalt, iron and manganese complexes showed three to four redox couples assigned to metal and ring based processes. Spectroelectrochemistry of the manganese derivative confirmed that the synthesized complex is MnIII(TPhPyrPc-2) and that the reduction of MnII(TPhPyrPc-2) to be centred on the ring and rather than on the metal, forming the MnII(TPhPyrPc-4) species. Also, the electrochemical polymerization of these newly synthesized pyrrole-substituted phthalocyanines has been demonstrated in the case of the cobalt complex and the electrocatalytic activity of the obtained film has been tested towards the oxidation of L-cysteine.
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- Date Issued: 2003
Synthesis, spectroscopy and photochemistry of octasubstituted thiol-derivatized phthalocyaninatozinc (II) complexes
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290401 , vital:56746 , xlink:href="https://doi.org/10.1016/S1387-7003(03)00218-1"
- Description: Synthesis, spectroscopic and photochemical characterization of phenylthiol-derivatized zinc phthalocyanine complex: 2,3,9,10,16,17,23,24-octa(4-methylphenylthio-)phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (3a) and its alkanethiol derivative, 2,3,9,10,16,17,23,24-octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (3b) are described. Spectroscopic analyses show that 3a has a higher aggregation tendency than 3b in organic solvents. Photochemical studies indicate that 3b is more photostable and more efficient at singlet oxygen generation than 3a.
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- Date Issued: 2003
The role of estuarine type in characterizing early stage fish assemblages in warm temperate estuaries, South Africa
- Authors: Strydom, Nadine A , Whitfield, Alan K , Wooldridge, T H
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447658 , vital:74664 , https://doi.org/10.1080/15627020.2003.11657192
- Description: Assemblages of early stage fishes (larval and early juvenile stages) were investigated and compared in seven permanently open and five intermittently open estuarine systems on the warm temperate Eastern Cape coast of South Africa. Estuarine type, by virtue of mouth state and prevailing physico chemical conditions, played a defining role in the structure of these fish assemblages. Clupeidae and Gobiidae were the dominant fish families in both estuarine types. Permanently open estuaries were characterized by the predominance of larvae and early juveniles of estuary dependent marine fish species while estuary resident fishes dominated intermittently open estuaries. Seasonal changes were observed in species density and diversity in both estuarine types. Species richness and diversity were highest in the permanently open Swartkops Estuary that is characterized by large nursery habitat availability. Species diversity was high in estuaries with a good supply of freshwater, that results in good recruitment of estuary dependent marine species. Similarly, freshwater deprived estuaries also displayed high species diversity and this was due to the higher incidence of marine straggler species in these systems. Salinity zones appeared to play a significant role in both species density and the presence or absence of species in both estuarine types. Mesohaline zones were found to be the most productive in terms of accumulator regions for larval stages.
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- Date Issued: 2003
The writing is on the wall: ways that work: useful solutions
- Authors: Amner, Roderick J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454938 , vital:75388 , https://hdl.handle.net/10520/EJC146296
- Description: When I proposed to 26 third-year journalism students that our writing class take inspiration from an idea pioneered in places as unfashiona-ble and inhospitable as the former Soviet Union and Nepal, I should have expected the icy stares. But happily, within five weeks, this winter of classroom discontent, had begun to thaw into a tentative spring of journalistic and pedagogical innovation.
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- Date Issued: 2003
Tropical fruit pests and pollinators: biology, economic importance, natural enemies and control, J.E. Peña, J.L. Sharp and M. Wysoki (Eds.): book review
- Authors: Villet, Martin H
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451790 , vital:75077 , https://hdl.handle.net/10520/EJC32522
- Description: This book will interest advanced students and scientists specializing in tropical fruit crops with a focus on horticulture, pollination biology, entomology and especially pest management. The introductory chapter starts with an examination of global trends and statistics in tropical fruit production, and goes on to generalize about their biology.
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- Date Issued: 2003
Use of indigenous riverine invertebrates in applied toxicology and water resource-quality management
- Authors: Scherman, Patricia , Palmer, Carolyn G , Muller, Nikite W J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438061 , vital:73432 , ISBN 1-86845-962-4 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/955-1-03.pdf
- Description: The National Water Policy (DWAF, 1997). and the National Water Act (No 36 of 1998)(NWA) provide the legal and management context for the application of results. The law and the policy are founded on the concepts of equity (fairness of access to water and water services) and sustainability (the opportunity to optimally use water resources now and into the future)(NWA, l (l)(xviii)(b)). The concept of sustainability is based on the understanding that on earth water comes packaged in aquatic ecosystems, and that the product, water, is intimately related to and affected by the structure and functioning of these ecosys-tems.(Aquatic ecosystems include rivers, lakes, wetlands, aquifers and estuaries. Impoundments act as artificial lakes connected to river sys-tems.) A key recognition during the development of the policy and the NWA was that" the environment" does not compete with users for re-sources-the environment (in this case aquatic ecosystems) is the re-source. Therefore a key poiicy of DWAF is that vi resource protection in order to achieve sustainable resource use. Resource protection is achieved through the implementation of resource directed measures (RDM) and source directed controls (SDC).
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- Date Issued: 2003