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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

Mitochondrial STAT3 and reactive oxygen species: a fulcrum of adipogenesis?

  • Authors: Kramer, Adam H , Kadye, Rose , Houseman, Pascalene S , Prinsloo, Earl
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/431674 , vital:72795 , xlink:href="https://doi.org/10.1080/21623996.2015.1084084"
  • Description: The balance between cellular lineages can be controlled by reactive oxygen species (ROS). Cellular differentiation into adipocytes is highly dependent on the production of ROS to initiate the process through activation of multiple interlinked factors that stimulate mitotic clonal expansion and cellular maturation. The signal transducer and activator of transcription family of signaling proteins have accepted roles in adipogenesis and associated lipogenesis. Non-canonical mitochondrial localization of STAT3 and other members of the STAT family however opens up new avenues for investigation of its role in the aforementioned processes. Following recent observations of differences in mitochondrially localized serine 727 phosphorylated STAT3 (mtSTAT3-pS727) in preadipocytes and adipocytes, here, we hypothesize and speculate further on the role of mitochondrial STAT3 in adipogenesis.
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  • Date Issued: 2015

Spectroscopic and nonlinear optical properties of the four positional isomers of 4α-(4-tert-butylphenoxy) phthalocyanine

  • Authors: Ngubeni, Grace N , Britton, Jonathan , Mack, John , New, Edward , Hancox, Ian , Walker, Marc , Nyokong, Tebello , Jones, Tim S , Khene,Samson M
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/241448 , vital:50940 , xlink:href="https://doi.org/10.1039/C5TC01601K"
  • Description: The spectroscopic and nonlinear optical properties of the positional isomers of metal free 4α-(4-tert-butylphenoxy) phthalocyanine are presented. Second order nonlinear polarizability (β), imaginary hyperpolarizability (Im(γ)) and imaginary susceptibility (Im[χ(3)]) values were determined for the four positional isomers. The measured β values of the four isomers displayed the following trend, C4h (34.0 × 10−5 m MW−1) > D2h (28.8 × 10−5 m MW−1) > C2v (22.8 × 10−5 m MW−1) > Cs (13.7 × 10−5 m MW−1).
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  • Date Issued: 2015

Synthesis and characterization of ZnO nanoparticle synthesized by a microwave-assisted combustion method and catalytic activity for the removal of ortho-nitrophenol

  • Authors: Assi, Navid , Mohammadi, Ali , Sadr Manuchehri, Q , Walker, Roderick B
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/183850 , vital:44075 , xlink:href="https://doi.org/10.1080/19443994.2014.891083"
  • Description: ZnO nanoparticles were manufactured using microwave-assisted combustion. The structural and morphological properties of the nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. Photocatalytic degradation of ortho-nitrophenol (O-NP) in aqueous solution using the synthesized nanoparticles was performed under UV–C irradiation and is reported for the first time. The effect of the initial O-NP concentration, amount of photocatalyst, pH, and salt was investigated during photodegradation. Analysis of the degraded samples using HPLC with UV detection revealed that photocatalysis in the presence of ZnO nanoparticles removed 98% of the O-NP in 5 h. In addition, the photocatalytic degradation kinetics of O-NP were studied, and the results suggest that the data are best fitted to pseudo-first-order kinetic and Langmuir–Hinshelwood models.
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  • Date Issued: 2015

Synthesis and photophysical properties of nanocomposites of aluminum tetrasulfonated phthalocyanine covalently linked to glutathione capped CdTe/CdS/ZnS quantum dots

  • Authors: Oluwole, David O , Britton, Jonathan , Mashazi, Philani N , Nyokong, Tebello
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/241379 , vital:50934 , xlink:href="https://doi.org/10.1016/j.synthmet.2015.04.015"
  • Description: Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was covalently linked with different sizes of glutathione capped CdTe/CdS/ZnS quantum dots (QDs). The photophysical and Förster resonance energy transfer (FRET) properties of the nanoconjugates were investigated. The CdTe/CdS/ZnS(6.3) nanocomposite showed the highest enhancement in its photophysical properties while (CdTe/CdS/ZnS(3.2) nanocomposite showed the least. Highest FRET efficiency was observed in the linked CdTe/CdS/ZnS(6.3) nanocomposites at 93%. Hence, the combination of CdTe/CdS/ZnS with ClAlTSPc exhibited excellent photophysical properties.
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  • Date Issued: 2015

The development of palladium (II)-specific amine-functionalized silica-based microparticles

  • Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/241083 , vital:50903 , xlink:href="https://doi.org/10.1080/01496395.2014.978017"
  • Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources.
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  • Date Issued: 2015

The development visions and attitudes towards urban forestry of officials responsible for greening in South African towns

  • Authors: Gwedla, Nanamhla , Shackleton, Charlie M
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/180856 , vital:43651 , xlink:href="https://doi.org/10.1016/j.landusepol.2014.07.004"
  • Description: The planting and maintenance of trees in public areas of South African towns is the responsibility of local municipalities. Therefore, it is necessary to appreciate the visions and attitudes of municipal officials and decision-makers in charge of such activities for an understanding of the distribution and abundance of trees along streets and in urban green spaces. We hypothesised that the town size and relative wealth and current extent of trees in public places would influence the visions of such officials. We therefore conducted 24 semi-structured interviews with the officials responsible for urban tree planting in 24 towns in the Eastern Cape province, whilst also assessing the abundance of street trees via GIS counts. The density of street trees was variable, ranging from 0.5 to 9.5 trees/ha. There were significantly positive relationships between town size, relative wealth measures and street tree density. Several of the managers did not include environmental issues or trees in vision of the future for their town, although most did. There was no relationship between the managers’ visions for the future and attitudes and current street tree density. Most of the managers experienced several constraints in trying to implement their vision, notably a lack of funds for urban forestry, limited space for tree planting in low-cost housing developments, vandalism, and lack of skilled personnel.
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  • Date Issued: 2015

The effect of ascorbic acid on the photophysical properties and photodynamic therapy activities of zinc phthalocyanine-single walled carbon nanotube conjugate on MCF-7 cancer cells

  • Authors: Ogbodu, Racheal O , Nyokong, Tebello
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/189066 , vital:44813 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.063"
  • Description: Zinc mono carboxy phenoxy phthalocyanine (1) was chemical modified with ascorbic acid via an ester bond to give ZnMCPPc-AA (2). Complexes 2 and 1 were coordinated to single walled carbon nanotubes via π–π interaction to give ZnMCPPc-AA-SWCNT (3) and ZnMCPPc-SWCNT (4) respectively. Complexes 2, 3 and 4 showed better photophysical properties: with improved triplet lifetimes and quantum yields, and singlet oxygen quantum yields when compared to 1 alone. The photodynamic therapy activities of complexes 1, 2, 3 and 4 were tested in vitro on MCF-7 breast cancer cells. Ascorbic acid suppresses the photodynamic therapy effect of 1, due to its ability to reduce oxidative DNA damage as a result of its potent reducing properties. The highest phototoxicity was observed for 4 which resulted in 77% decrease in cell viability, followed by 3 which resulted in 67% decrease in cell viability. This shows the importance of combination therapy, where the phthalocyanines are the photodynamic therapy agents and single walled carbon nanotubes are the photothermal therapy agents.
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  • Date Issued: 2015

The effect of long-distance transportation on the fitness of irradiated false codling Moth (Lepidoptera: Tortricidae) for use in a sterile insect release program

  • Authors: Nepgen, Eugene S , Hill, Martin P , Moore, Sean D
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/423835 , vital:72098 , xlink:href="https://doi.org/10.1093/jee/tov246"
  • Description: The effect of cold immobilization and long-distance transport of irradiated Thaumatotibia leucotreta (Meyrick) on the flight ability of male (?) and female (/) moths, the longevity of male and female moths, and the realized fecundity of mating pairs CIM (chilled irradiated moths) / CIM?, CIM/ NIP (nonirradiated pupae) ?, NIP/ CIM?, and NIP/ NIP? was examined to improve application of the sterile insect technique (SIT). Adult moths treated with 150 Gy of gamma radiation were immobilized with cold temperature between 4 and 6C inside a polyurethane cooler box and transported for 12 h by road from Citrusdal, Western Cape Province, to Addo, Eastern Cape Province. Nonirradiated moths were transported as pupae inside a cardboard tray and removed by hand after which male and female pupae were separated and placed inside containers for eclosion. Male and female moths were individually placed inside petri dishes to determine longevity or paired with irradiated and nonirradiated counterparts to evaluate realized fecundity before incubation in 100% darkness at 25C and 75% relative humidity. Flight tests were conducted indoors at 25C by release of individual moths per hand. A significant decrease in flight ability and longevity of irradiated false codling moth was found after handling, cold immobilization, and transport, although critically, realized fecundity was not affected. Because of the impact of long-distance transport on quality of the released insects as well as the efficacy of SIT, comprehensive protocols for this critical step in the process need to be developed for a pestiferous insect with phytosanitary status such as false codling moth.
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  • Date Issued: 2015

Towards an Extensible Generic Agent-Based Simulator for Mammals

  • Authors: Carse, Stephen , Bradshaw, Karen L
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/475296 , vital:77793 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9856380"
  • Description: Modelling tools are widely used by national parks, both within South Africa and in countries around the world. The modelling of animal behaviour, particularly in South Africa and other African countries, is well established. These models, however, tend to be developed with one particular application and species in mind and are not reusable in other scenarios, requiring further development work for the addition of another species. This paper presents an approach towards developing an agent-based generic system that simulates a range of mammal behaviours by building a set of core behaviours that can be parameterised according to the needs of each species. The system uses XML notation for the definition of a species and provides a GUI tool that produces the XML required to simulate a species and set up the initial animals present in the simulation. Various feedback tools allow the simulation to be examined and analysed in detail to ascertain the success of the simulation of the mammal behaviours and those behaviours' adaptation to various different species.
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  • Date Issued: 2015

A comparative photophysicochemical study of mono substituted phthalocyanines grafted onto silica nanoparticles

  • Authors: Fashina, Adebayo , Antunes, Edith M , Nyokong, Tebello
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/193844 , vital:45399 , xlink:href="https://doi.org/10.1142/S1088424614500138"
  • Description: In this study, we report on the covalent linking of carboxylic acid functionalized silica nanoparticles with zinc phthalocyanine mono-substituted non-peripherally and peripherally with either a 4-amino phenoxy (1, peripheral and 2, non-peripheral) or an amino group (3 peripheral). The grafting is achieved via the formation of an amide bond between the carboxylic acid of the silica nanoparticles and the amino group of the phthalocyanine complexes. The hybrid nanoparticles retained the amorphous nature of silica nanoparticles after conjugation. A slight decrease in fluorescence and a general improvement in triplet quantum yields compared to free Pcs were observed. Triplet lifetimes for 2-SiNPs and 3-SiNPs also improved when compared to the free phthalocyanine. The changes in singlet oxygen quantum yields upon conjugation were minimal.
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  • Date Issued: 2014

A reflection on the use of case studies as a methodology for social learning research in sub Saharan Africa

  • Authors: Cundill, Georgina , Lotz-Sisitka, Heila, 1965- , Mukute, Mutizwa , Ali, Million Belay , Shackleton, Sheona E , Kulundu-Bolus, Injairu M
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/182832 , vital:43884 , xlink:href="https://doi.org/10.1016/j.njas.2013.04.001"
  • Description: A recent review has highlighted that the methodology most commonly employed to research social learning has been the individual case study. We draw on four examples of social learning research in the environmental and sustainability sciences from sub-Saharan Africa to reflect on possible reasons behind the preponderance of case study research in this field, and to identify common elements that may be significant for social learning research more generally. We find that a common interest in change oriented social learning, and therefore processes of change, makes case studies a necessary approach because long term process analyses are required that are sensitive to social-ecological contexts. Common elements of the examples reflected upon included: a focus on initiating, tracking and/or understanding a process of change toward sustainability; long term research; an action research agenda that involves reflecting on data with research participants; and temporal, process based analysis of data coupled with in-depth theoretical analysis. This paper highlights that there is significant scope for exploratory research that compares case studies of social learning research to generate a deeper understanding of social learning processes, and their relationship to human agency and societal change.
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  • Date Issued: 2014

Argumentative and trustworthy scholars

  • Authors: McKenna, Sioux , Boughey, Chrissie
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/187216 , vital:44580 , xlink:href="https://doi.org/10.1080/13562517.2014.934351"
  • Description: Research-intensive universities, such as the Russell Group in the UK, the Ivy League Colleges in the USA and the Sandstone Universities in Australia, enjoy particular status in the higher education landscape. They are, however, also often associated with social elitism and selectivity, and this has led to critique as higher education systems seek to widen access. This article looks at how academic staff are discursively constructed in five such institutions in South Africa through an analysis of documentation submitted as part of a national review. Three interrelated discourses are identified: a discourse of ‘staff as scholars’ whereby research is privileged over teaching, a discourse of ‘academic argumentation’ whereby a critical disposition is valued and is called upon by academics to resist development initiatives and a discourse of ‘trust’ whereby it is assumed that academics share a value system and should thus be trusted to undertake quality teaching without interference.
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  • Date Issued: 2014

Behavior of palladium nanoparticles in the absence or presence of cobalt tetraaminophthalocyanine for the electrooxidation of hydrazine

  • Authors: Maringa, Audacity , Nyokong, Tebello
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/189796 , vital:44932 , xlink:href="https://doi.org/10.1002/elan.201400028"
  • Description: We report on the electrodeposition of palladium nanoparticles (PdNPs) on a glassy carbon electrode (GCE) and onto a poly-CoTAPc-GCE (CoTAPc=cobalt tetraamino phthalocyanine) surface. The electrodes are denoted as PdNPs-GCE and PdNPs/poly-CoTAPc-GCE, respectively. PdNPs/poly-CoTAPc-GCE showed the best activity for the oxidation of hydrazine at the lowest potential of −0.28 V and with the highest currents. The results were further supported by electrochemical impedance spectroscopy (EIS) which showed that there was less resistance to charge transfer for PdNPs/poly-CoTAPc-GCE compared to PdNPs-GCE. The catalytic rate constant for hydrazine oxidation was 6.12×108 cm3 mol−1 s−1 using PdNPs/poly-CoTAPc-GCE.
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  • Date Issued: 2014

Contrasting architecture of key African and Australian savanna tree taxa drives intercontinental structural divergence

Electrocatalytic behahiour of cobalt tetraamino-phthalocyanine in the presence of a composite of reduced graphene nanosheets and of multi-walled carbon nanotubes

  • Authors: Nyoni, Stephen , Nyokong, Tebello
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/189784 , vital:44931 , xlink:href="https://doi.org/10.1016/j.electacta.2014.05.093"
  • Description: A composite of multi-walled carbon nanotubes (MWCNT) with reduced graphene nanosheets (rGNS-2) was developed in order to minimize the restacking of the latter. The composite was used to modify a glassy carbon electrode (GCE). GCE was further modified with cobalt tetraamino phthalocyanine (CoTAPc). The modified electrode is represented as rGNS-2-MWCNT-CoTAPc-GCE. X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electrochemical microscopy and Raman spectroscopy were used to explore into surface functionalities, morphology and topography of the nanocomposite. The rGNS-2-MWCNT-CoTAPc-GCE had a low limit of detection of 3.32 × 10−8 M towards the detection of paraguat as a test analyte. A mechanism for paraquat detection using an rGNS-2-MWCNT-CoTAPc-GCE is also proposed in this work.
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  • Date Issued: 2014

Low-cost housing developments in South Africa miss the opportunities for household level urban greening

  • Authors: Shackleton, Charlie M , Hebinck, Paul , Kaoma, Humphrey , Chishaleshale, Mwale , Chinyimba, Abby , Shackleton, Sheona E , Gambiza, James , Gumbo, Davison
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/180967 , vital:43677 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.10.002"
  • Description: Most developing countries of the world are experiencing large-scale migration from rural to urban areas. Many new migrants end up in low-cost or informal areas and slums with attendant environmental concerns. One dimension of improved urban sustainability is the provision of green spaces and trees. Whilst many countries have urban greening programmes for public spaces and streets, few have considered the status and potential contribution of trees from resident's own gardens. This paper reports firstly on the policy environment for urban forestry and greening in South Africa and secondly on the maintenance, use and appreciation of trees on private homesteads of residents of new and older low-income suburbs as well as informal housing areas from three small towns in South Africa. In particular we examine if the most recent centrally planned and built low-income housing schemes (called RDP suburbs in South Africa) have considered and incorporated plans or spaces for urban greenery in peoples’ homesteads. We found that broad environmental and sustainability concerns and statements are common in urban development and housing policies, but specific guidelines for implementation are generally absent. More specifically, urban forestry and tree planting are rarely mentioned in the broader land use and environmental policies other than the national forest act and subsequent regulations, but even there it is relatively superficial. In the study towns the prevalence, density and number of species of trees was lowest in the new RDP suburbs relative to the township and informal areas. Consequently, the contribution of tree products to local livelihoods was also lower in the RDP areas. Yet there were no differences in the level of appreciation of the value and intangible benefits of trees between residents from the three different suburbs. This shows that the failure to plan for and accommodate trees in new low-cost housing developments is missing an opportunity to improve overall urban sustainability and liveability and constraining the potential flows of tangible and intangible benefits to urban residents. Making opportunities for such in older suburbs is challenging because of space limitations and cost implications of retrospective provisions, but incorporation into plans for new low-cost housing development should be possible.
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  • Date Issued: 2014

Photophysical behavior of Zn aminophenoxy substituted phthalocyanine conjugates with carboxylic acid-coated silica nanoparticles

  • Authors: Fashina, Adedayo , Antunes, Edith M , Nyokong, Tebello
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/193802 , vital:45397 , xlink:href="https://doi.org/10.1016/j.molstruc.2014.04.034"
  • Description: This work reports on the grafting of silica nanoparticles with zinc phthalocyanine complexes tetra-substituted non-peripherally and peripherally with a 4-amino phenoxy group. The phthalocyanine dyes have free amino groups, facilitating covalent attachment of the dyes on the silica surface via amide bond formation. The surface area of the functionalized silica nanoparticles increased on conjugation but the pore volumes were reduced. The phthalocyanine functionalized silica nanoparticles showed lower fluorescence quantum yields as well as shorter triplet lifetimes compared to the free phthalocyanines in dimethyl formamide. For the non-peripherally substituted phthalocyanines increases in triplet yield quantum yields, lifetimes, and singlet oxygen quantum yields were observed.
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  • Date Issued: 2014

Photophysichochemical behavior of carbazole derivatized zinc phthalocyanine in the presence of ZnO microparticles and when embedded in electrospun fibers

  • Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/193860 , vital:45400 , xlink:href="https://doi.org/10.1016/j.dyepig.2013.12.019"
  • Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively.
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  • Date Issued: 2014

Phytoplankton community diversity along a river-estuary continuum

  • Authors: Dalu, Tatenda , Froneman, P William , Richoux, Nicole B
  • Date: 2014
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/457284 , vital:75622 , xlink:href="https://hdl.handle.net/10520/EJC156752"
  • Description: In this paper we examine the aspects of phytoplankton communities along a riverine-estuarine continuum in the Kowie system, Eastern Cape (South Africa). This study aims to relate the phytoplankton population community structure to physicochemical parameters and estimate the different chlorophyll-a concentrations for the Kowie system. Eight sampling sites along a 70 km reach of the Kowie system were sampled over a one-year period. One hundred and seventy-eight species belonging to 78 genera were recorded within the riverine-estuarine continuum. Diatoms were predominant, accounting for 81.9% of the total abundance. The estuary had 98 species (55 genera) recorded whereas the river had 141 species (67 genera). Using a two-way analysis of variance (ANOVA), species richness was found to differ significantly amongst seasons. The chl-a concentration along the estuarine-riverine continuum increased from spring to a high in summer (river mean = 7.9 mg m -3 and estuary mean = 3.3 mg m -3 ) before decreasing to a low in winter. Kruskal Wallis ANOVA showed significant differences among chl-a concentration with seasons and sites. Redundancy analysis identified five factors salinity, water depth, aerial cover, nitrates and ammonia that were significant (p is less than 0.05) in affecting phytoplankton variation. The relatively small study indicates the need for further monitoring to gain a better understanding of Kowie system phytoplankton.
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  • Date Issued: 2014
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