South Africa’s new democrats : a 2002 profile of democracy in the making
- Authors: Moller, Valerie , Hanf, T
- Date: 2007
- Language: English
- Type: Book , text
- Identifier: vital:539 , http://hdl.handle.net/10962/d1010768
- Description: [From the introduction]: South Africa’s dramatic conversion to democracy has been heralded as a modern-day miracle. In former Nobel peace prize winner Archbishop Tutu’s words, it was ‘touch and go’ whether all conflicting parties would participate in the first non-racial elections in April 1994. The ‘rainbow nation’, as the new South Africa liked to call itself in the first years of democracy, was heralded as a beacon of hope and enlightenment for Africa and the world. Since 1994, South Africa has successfully conducted two further national elections that have been declared essentially free and fair. The country has emerged as a leading representative of the economic and political interests of developing countries and the South in the international arena. The question is whether living under democracy has influenced the manner in which South Africans see themselves, their country and the world around them. This report seeks to document how South Africans think and feel some eight years into democracy about issues that are important in their own lives and have significance for the future of their society. The study covers personal experiences, attitudes and beliefs, and the aspirations and fears of ordinary people. It seeks to identify the sentiments and collective experiences that may contribute to or hinder the consolidation of democracy in years to come. The report is based on an inquiry conducted in March 2002 among over two thousand South African adults over 16 years of age in a nationally representative MarkData survey that included all regions of the country. , Lettres de Byblos / Letters from Byblos. A series of occasional papers published by UNESCO Centre International des Sciences de l’Homme International Centre for Human Sciences
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- Date Issued: 2007
Spatial and seasonal distribution patterns of juvenile and adult raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J , Cliff, G
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126997 , vital:35942 , https://doi.10.1071/MF06018
- Description: Crucial to effective fisheries management is a thorough understanding of the stock structure of a population. Understanding the spatial and seasonal distribution patterns of a species is necessary to define habitat use and evaluate the potential effects of exploitation and anthropogenic activities. This is particularly important for a species such as the raggedtooth shark (Carcharias Taurus Rafinesque, 1810), whose life-history characteristics make it particularly susceptible to over-exploitation (Pollard et al. 1996; Smith et al. 1998; Compagno 2001). Exploitation, even at low levels for a slow-growing, late-maturing species that only produces two pups every other year, could reduce the population growth rate, could reduce the population growth rate to values of λ<1.0, resulting in severe population declines in a very short time period (Baum et al. 2003).
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- Date Issued: 2007
Spatial patterns in the biology of the chokka squid, Loligo reynaudii on the Agulhas Bank, South Africa
- Authors: Olyott, L J H , Sauer, Warwick H H , Booth, Anthony J
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127053 , vital:35947 , https://doi.10.1007/s11160-006-9027-5
- Description: Although migration patterns for various life history stages of the chokka squid (Loligo reynaudii) have been previously presented, there has been limited comparison of spatial variation in biological parameters. Based on data from research surveys; size ranges of juveniles, subadults and adults on the Agulhas Bank were estimated and presented spatially. The bulk of the results appear to largely support the current acceptance of the life cycle with an annual pattern of squid hatching in the east, migrating westwards to offshore feeding grounds on the Central and Western Agulhas Bank and the west coast and subsequent return migration to the eastern inshore areas to spawn. The number of adult animals in deeper water, particularly in autumn in the central study area probably represents squid spawning in deeper waters and over a greater area than is currently targeted by the fishery. The distribution of life history stages and different feeding areas does not rule out the possibility that discrete populations of L. reynaudii with different biological characteristics inhabit the western and eastern regions of the Agulhas Bank. In this hypothesis, some mixing of the populations does occur but generally squid from the western Agulhas Bank may occur in smaller numbers, grow more slowly and mature at a larger size. Spawning occurs on the western portion of the Agulhas Bank, and juveniles grow and mature on the west coast and the central Agulhas Bank. Future research requirements include the elucidation of the age structure of chokka squid both spatially and temporally, and a comparison of the statolith chemistry and genetic characterization between adults from different spawning areas across the Agulhas Bank.
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- Date Issued: 2007
Spectroscopic characterisation and interactions of sulfonated titanium and tantalum phthalocyanines with methyl viologen
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283129 , vital:55913 , xlink:href="https://doi.org/10.1016/j.ica.2006.12.035"
- Description: Sulfonated OTiPc(S)n and (Cl3)TaPc(S)n complexes are prepared and characterised by spectroscopic methods in DMSO, methanol and PBS 7.4. The dominant sulfonated species was the disulfophthalocyanine. OTiPc(S)n is highly aggregated in PBS 7.4 solution and tends to partially monomerise, on addition of Triton X-100, while (Cl3)TaPc(S)n showed broadened spectra in all solvents and was not affected by Triton X-100. The absorption and excitation spectra of OTiPc(S)n are similar and are mirror images of their emission spectra in DMSO, but differ in PBS and methanol. The fluorescence quantum yields (ϕF) and lifetimes (τF) were larger in DMSO than in methanol. In PBS 7.4, however, the ϕF and τF values were significantly smaller for OTiPc(S)n, which is typical of aggregated species. Gradual addition of the electron-acceptor MV2+ to solutions of MPc(S)n complexes resulted in the fluorescence quenching of complexes with higher quenching observed for OTiPc(S)n. The interaction of the MPc(S)n complexes with MV2+, and hence the stoichiometry and association constants are evaluated by means of Job method.
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- Date Issued: 2007
Study South Africa
- Authors: International Education Association of South Africa (IEASA) , Higher Education South Africa (Organization) , Kishun, Roshen
- Date: 2007
- Subjects: Education, Higher -- South Africa , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/65090 , vital:28685 , ISBN 9780620391634
- Description: [Extract from message from Minister of Higher Education, Hon. Naledi Pandor]: It gives me great pleasure to endorse the 7th edition of Study South Africa. The International Education Association of South Africa (IEASA) has once again produced a publication that provides valuable insights and information about South African public universities and their place in the global higher education arena I welcome this publication and congratulate IEASA for its hard work in promoting our higher education institutions internationally. Study South Africa gives a comprehensive picture of higher education in our country. At a glance, the enquirer is able to see all that South African higher education has to offer diversity in terms of institutions, the wide range of affordable courses on offer, the international acceptability of South African qualifications as well as the rich multi-cultural experiences of our campuses. In short, the Guide provides a summary of everything that will assist the potential student to actualise his or her full potential. South African higher education is founded on broad social values such as respect for human life and dignity, commitment to equality and human rights, respect for diversity and nonsexism. Our education system seeks to construct citizens who are conscious of these values and therefore aware of their responsibilities in life and in the lives of others. These values are reflected in the diverse offerings by institutions covered in the Guide. In addition, we have specific mechanisms in place to facilitate internationalisation, and our immigration policies have been relaxed to make it easier for international students, academics and other higher education staff to enter the country and stay for the duration of their planned activity. We also subsidise students from the continent in terms of our policy on the state subsidisation of foreign students at higher education institutions. South Africa shares the global concern about the digital and information divide. We are of the view that access to information is empowering and would therefore like to see as many citizens of our country and the continent connected with the rest of the world, both digitally and in terms of knowledge. By staying in touch with the rest of the world through information sharing and exchange programmes, we minimise this information gap. It is for this reason, therefore, that the work of IEASA in the form of this publication is applauded, because it seeks to promote such exchanges and information sharing. There is no question that through internationalisation we can impact on our political, economic, cultural and social transformation. We can also address our skills shortage, build research capacity, enrich curricula and enhance the student experience. Collectively higher education institutions in South Africa offer an impressive array of information and communication technologies, well stocked and interconnected libraries and some scholars who are among the best in the world, making the country a destination of choice for both Africans and students from abroad. We aspire to make all our international partners, students and staff feel at home and content with what our institutions offer them, pleasant living and study or work environments. We want them to be proud of their association with South African higher education and be ambassadors for the system once they leave South Africa. , 7th Edition
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- Date Issued: 2007
Submerged membrane bioreactor and secondary digestion for the treatment of wine distillery wastewater: Part I: Raw wine distillery wastewater digestion
- Authors: Melamane, Xolisa L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76139 , vital:30511 , https://www.prt-parlar.de/download_feb_2007/
- Description: A combination of a submerged membrane bioreactor (SMBR) and a secondary digester was tested for the treatment of wine distillery wastewater (WDW). The experimental system, consisting of four individual reactors, was tested during a 30-days study. Buffering of pH was achieved by mixing the feed stream of the system with 1000 mg/l of CaCO3 and K2HPO4 for the initial 10 days of the bioreactor system operation, and with 8000 mg/l of CaCO3 and 4000 mg/l of K2HPO4 for the remainder of the study. Buffering proved to be significant for optimum performance of the system in removal of soluble chemical oxygen demand (CODS), and volatile fatty acids (VFAs). Different batches of WDW used for feeding the reactor had variable compositions with respect to concentrations of nitrates, ammonium and the total concentration of phenolic compounds. Am-monium accumulated in the secondary digester after 14 days of treatment system operation, indicating the time required for the establishment of anaerobic conditions in the system. An additional step would be required for removal of phosphates from the effluent of the bioreactor, e.g., reverse osmosis, if the effluent is to be reused in production or other applications.
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- Date Issued: 2007
Submerged membrane bioreactor and secondary digestion in the treatment of wine distillery waste: Part II: the effect of fungal pre-treatment on wine distillery wastewater digestion
- Authors: Melamane, Xolisa L , Strong, Peter James , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76150 , vital:30514 , https://www.prt-parlar.de/download_feb_2007/
- Description: The effect of fungal pre-treatment using Trametes pubescens on the anaerobic digestion ultrafiltration treatment of wine distillery wastewater (WDW) was studied. The downstream biological treatment system, consisting of four individual reactors, was operated for 30 days. pH buffering was achieved by mixing the pre-treated system feed with CaCO3 and K2HPO4; this proved significant for optimum performance of the system in removal of soluble chemical oxygen demand (CODS). The experimental system was shown to eliminate an average of 86 (± 4) % of CODS present in the pre-treated WDW. Treatment in a submerged membrane bioreactor (SMBR) and subsequent secondary digester, together with pH buffering using CaCO3 and K2HPO4, led to the stabilisation of CODS removal. The residual CODS levels in the final effluent were approximately 400 mg/l, significantly lower than the concentrations observed when treating raw WDW, indicating that fungal pre-treatment might have provided additional nutrients for removal of recalcitrant components of the wastewater. The resulting effluent of the system is rich in nitrates and phosphates. Together with the residual organic content it might be used as a fertiliser. Alternatively, if water management of the wine distillery is an issue, a membrane process, such as reverse osmosis or nanofiltration could be applied to bring the parameters of the water to meet the technological needs.
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- Date Issued: 2007
Surface chemistry and electrocatalytic behaviour of tetra-carboxy substituted iron, cobalt and manganese phthalocyanine monolayers on gold electrode
- Authors: Mashazi, Philani N , Westbroek, Philippe , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268806 , vital:54233 , xlink:href="https://doi.org/10.1016/j.electacta.2007.08.044"
- Description: Surface chemistry and electrocatalytic properties of self-assembled monolayers of metal tetra-carboxylic acid phthalocyanine complexes with cobalt (Co), iron (Fe) and manganese (Mn) as central metal ions have been studied. These phthalocyanine molecules are immobilized on gold electrode via the coupling reaction between the ring substituents and pre-formed mercaptoethanol self-assembled monolayer (Au-ME SAM). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed chemisorption of mercaptoethanol via sulfur group on gold electrode and also coupling reaction between phthalocyanines and Au-ME SAM. Electrochemical parameters of the immobilized molecules show that these molecules are densely packed with a perpendicular orientation. The potential applications of the gold modified electrodes were investigated towards L-cysteine detection and the analysis at phthalocyanine SAMs. Cobalt and iron tetra-carboxylic acid phthalocyanine monolayers showed good oxidation peak for L-cysteine at potentials where metal oxidation (MIII/MII) takes place and this metal oxidation mediates the catalytic oxidation of L-cysteine. Manganese tetra-carboxylic acid phthalocyanine monolayer also exhibited a good catalytic oxidation peak towards L-cysteine at potentials where MnIV/MnIII redox peak occurs and this redox peak mediates L-cysteine oxidation. The analysis of cysteine at phthalocyanine monolayers displayed good analytical parameters with good detection limits of the orders of 10−7 mol L−1 and good linearity for a studied concentration range up to 60 μmol L−1.
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- Date Issued: 2007
Syntheses and photophysics of new phthalocyanine derivatives of zinc, cadmium and mercury
- Authors: Chidawanyika, Wadzanai J U , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283940 , vital:56005 , xlink:href="https://doi.org/10.1039/B615663K"
- Description: The syntheses of novel tetra{2,(3)-pyridyloxyphthalocyaninato} complexes of zinc, cadmium and mercury (TPyZnPc, TPyCdPc and TPyHgPc) are presented. Their spectral and photophysical properties (as well as those of their unsubstituted counterparts: ZnPc, CdPc and HgPc) are investigated. TPyZnPc and TPyCdPc are aggregated in non-coordinating solvents such as chloroform, while TPyHgPc is demetallated, as evident from their respective absorption spectra. The trends in fluorescence (ΦF), triplet (ΦT) and singlet oxygen (ΦΔ) quantum yields are explained in terms of relative strengths of spin–orbit coupling induced by the respective central metal ions in the complexes. The effect of the pyridyloxy substituents is a decrease in ΦF and an increase in ΦT values. The complexes are less fluorescent in DMSO but possess higher ΦT, triplet lifetimes (τT) and ΦΔ therein.
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- Date Issued: 2007
Synthesis and electrochemical properties of benzyl-mercapto and dodecyl-mercapto tetrasubstituted manganese phthalocyanine complexes
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Westbroek, Philippe , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281321 , vital:55713 , xlink:href="https://doi.org/10.1016/j.electacta.2006.09.002"
- Description: Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mercapto) phthalocyanine (MnTDMPc) complexes were synthesized and their spectral and electrochemical properties are reported. Cyclic voltammetric data showed three reversible to quasi-reversible and two irreversible redox processes for both complexes. Ring substituents influenced the positions of both oxidation and reduction redox couples. Spectroelectrochemistry confirmed the first two reductions to be due to MnIIIPc2−/MnIIPc2− and MnIIPc3−/MnIIPc2− processes. The first example of a formation of self-assembled monolayers (SAMs) using thiol substituted MnPc complexes is presented, the SAMs were found to show blocking characteristics towards some faradaic reactions.
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- Date Issued: 2007
Synthesis and electrochemical properties of purple manganese (III) and red titanium (IV) phthalocyanine complexes octa-substituted at non-peripheral positions with pentylthio groups
- Authors: Mbambisa, Gcineka , Tau, Prudence , Antunes, Edith M , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271252 , vital:54525 , xlink:href="https://doi.org/10.1016/j.poly.2007.08.007"
- Description: The synthesis and electrochemical characterisation of octapentylthiophthalocyaninato manganese (III) acetate (4) and octapentylthiophthalocyaninato titanium (IV) oxide (5) complexes are reported. The complexes have an unusual purple (4) and red (5) colouration since the Q-band is shifted to the near infrared region with Q-band maxima at 893 nm and 808 nm in dichloromethane for 4 and 5, respectively. The structures of the complexes were confirmed by elemental analysis and interpretation of their spectroscopic data, including 2D NMR. The cyclic voltammetry (CV) of the Mn complex (4) showed four quasi reversible couples. The reduction processes are attributed to MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 and the oxidation processes to MnIVPc−2/MnIIIPc−2 and MnIVPc−1/MnIVPc−2. The processes were confirmed by spectroelectrochemistry. A well-defined spectrum of the rare MnIVPc−2 species is reported. The CV of the Ti complex (5) showed two well-resolved reduction processes due to TiIVPc−2/TiIIIPc−2 and TiIIIPc−2/TiIIPc−2. However, oxidation processes of the complex revealed adsorption behaviour and resulted in decomposition on electrolysis using spectroelectrochemistry.
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- Date Issued: 2007
Synthesis and photodynamic potential of tetra-and octa-triethyleneoxysulfonyl substituted zinc phthalocyanines
- Authors: Atilla, Devrim , Savdan, Nil , Durmus, Mahmut , Gürek, Ayşe Gül , Khan, Tania , Rück, Angelika , Walt, Heinrich , Nyokong, Tebello , Ahsen, Vefa
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281342 , vital:55715 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.022"
- Description: Synthesis of the water soluble zinc phthalocyanines (3, 4) obtained from the phthalonitriles substituted with oligo(ethyleneoxy)thia groups are described. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, including HSQC, HMBC and COSY bidimensional correlation techniques, electronic spectroscopy and mass spectra. The aggregation behaviour of the phthalocyanine compounds (3, 4) was investigated using UV–vis spectroscopy in dimethylsulphoxide. Photochemical and photophysical measurements were conducted on oligo(ethyleneoxy)thia appended zinc phthalocyanines. General trends are described for quantum yields of photodegredation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds. The phototoxicity against cancer cells of the new compounds was investigated during several in vitro experiments. The dye-sensitized photooxidation of 1,3-diphenylisobenzofurane via 1O2 was studied in dimethylsulphoxide.
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- Date Issued: 2007
Synthesis and solvent effects on the electronic absorption and fluorescence spectral properties of substituted zinc phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293279 , vital:57071 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
- Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
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- Date Issued: 2007
Synthesis and solvent effects on the electronic absorption and fluorescence spectral properties of substituted zinc phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283140 , vital:55914 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
- Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
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- Date Issued: 2007
Synthesis, photophysical and photochemical properties of aryloxy tetra-substituted gallium and indium phthalocyanine derivatives
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281431 , vital:55724 , xlink:href="https://doi.org/10.1016/j.tet.2006.11.089"
- Description: The synthesis, photophysical and photochemical properties of the tetra-substituted aryloxy gallium(III) and indium(III) phthalocyanines are reported for the first time. General trends are described for photodegradation, singlet oxygen, fluorescence, and triplet quantum yields and triplet lifetimes of these compounds. The introduction of phenoxy and tert-butylphenoxy substituents on the ring resulted in lowering of fluorescence quantum yields and lifetimes, and triplet quantum yields, and an increase of kIC, kISC, and kF. Photoreduction of the complexes was observed during laser flash photolysis. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.41 to 0.91. Thus, these complexes show potential as Type II photosensitizers.
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- Date Issued: 2007
Synthesis, Photophysical and Photochemical Properties of Poly (oxyethylene)‐Substituted Phthalocyaninato Oxotitanium (IV) Complexes
- Authors: Atilla, Devrim , Durmus, Mahmut , Yılmaz, Özgür , Gürek, Ayşe Gül , Ahsen, Vefa , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271263 , vital:54526 , xlink:href="https://doi.org/10.1002/ejic.200700057"
- Description: The synthesis, photophysical and photochemical properties of tetra- and chlorotetrapoly(oxyethylene)-substituted oxotitanium(IV) phthalocyanines are reported for the first time. The new compounds were characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. These complexes showed monomeric behaviour in solution. General trends are described for photodegredation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethyl sulfoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The complexes showed high triplet quantum yields and triplet lifetimes in DMSO. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism), were 0.72 and 0.78 for 3a and 5a, respectively. Thus, these complexes show potential as Type II photosensitizers. These complexes were also quenched by benzoquinone for fluorescence quenching studies.
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- Date Issued: 2007
Synthesis, photophysical and photochemical properties of tetra-and octa-substituted gallium and indium phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271276 , vital:54529 , xlink:href="https://doi.org/10.1016/j.poly.2007.03.007"
- Description: The synthesis, photophysical and photochemical properties of the tetra- and octa-[4-(benzyloxyphenoxy)] substituted gallium(III) and indium(III) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. General trends are described for quantum yields of photodegredation, fluorescence quantum yields and lifetimes, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO). Substituted indium phthalocyanine complexes (7b–9b) showed much higher quantum yields of triplet state and shorter triplet lifetimes, compared to the substituted GaPc derivatives due to enhanced intersystem crossing (ISC) in the former. The gallium and indium phthalocyanine complexes showed phototransformation during laser irradiation due to ring reduction. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.51 to 0.94. Thus, these complexes show potential as photodynamic therapy of cancer.
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- Date Issued: 2007
Synthesis, photophysical and photochemical studies of new water-soluble indium (III) phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283976 , vital:56007 , xlink:href="https://doi.org/10.1039/b618478b"
- Description: The preparation of water-soluble indium(III)phthalocyanine complexes is described for the first time in this study. Peripherally and non-peripherally 3-hydroxypyridine tetrasubstituted indium(III) phthalocyanines (5a, 6a) and their quaternarized derivatives (5b, 6b) have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternarized compounds (5b, 6b) show excellent solubility in water, which makes them potential photosensitizers for use in photodynamic therapy (PDT) applications. Photochemical and photophysical measurements were conducted on 3-pyridyloxy appended indium(III) phthalocyanines in dimethylsulfoxide (DMSO) for non-ionic (5b, 6b) derivatives. General trends are described for quantum yields of photodegradation, fluorescence lifetimes, fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) are very high (ΦΔ > 0.55). Thus, these complexes may be useful as Type II photosensitizers.
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- Date Issued: 2007
The deployment of an e-commerce platform and related projects in a rural area in South Africa
- Authors: Dalvit, Lorenzo , Muyingi, H Hyppolite , Terzoli, Alfredo , Thinyane, Mamello
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428545 , vital:72519 , https://nru.uncst.go.ug/bitstream/handle/123456789/6552/Information%20Communica-tion%20Technologies%20%20page%20410.pdf?sequence=1andisAllowed=y#page=256
- Description: In our paper we describe the development and deployment of an ecommerce platform in Dwesa, a rural area in the former homeland of Transkei in South Africa. The system is designed to promote tourism and advertise local arts, crafts and music, and it entails a number of re-lated projects. Deployment of infrastructure, technical support, promo-tion of the initiative and teaching of computer literacy take place during monthly visits of approximately one week, and involve young research-ers from two universities (one previously disadvantaged; the other his-torically privileged). This ensures a synergy between technical exper-tise and understanding of the local context. Findings so far emphasise the importance of contextualising the intervention to suit local needs and adjust to the local context. The platform is currently being extended to include e-government, e-learning and e-health capabilities. If proven successful, this model can be exported to similar areas in South africa and in the rest of Africa. This could open up potential opportunities for the still unexplored market for ICT in rural Africa.
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- Date Issued: 2007
The effect of physico-chemical parameters and chemical compounds on the activity of β-d-galactosidase (B-GAL), a marker enzyme for indicator microorganisms in water
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6470 , http://hdl.handle.net/10962/d1005800 , https://doi.org/10.1016/j.chemosphere.2007.02.050
- Description: The presence of coliforms in polluted water was determined enzymatically (in situ) by directly monitoring the activity of beta-d-galactosidase (B-GAL) through the hydrolysis of the yellow chromogenic subtrate, chlorophenol red beta-d-galactopyranoside (CPRG), which produced a red chlorophenol red (CPR) product. The objectives of this study were to monitor the effect of compounds commonly found in the environment and used in water treatment on a B-GAL CPRG assay and to investigate the differences between the environmental B-GAL enzyme and the pure commercial enzyme. Environmental B-GAL was optimally active at pH 7.8. Two temperature optima were observed at 35 and 55 degrees C, respectively. B-GAL activity was strongly inhibited by silver and copper ions. While calcium and ferrous ions at lower concentrations (50-100mgl(-1)) increased the enzyme activity, a reduction was observed at higher concentrations (200mgl(-1)). Sodium hypochlorite, normally used in rural areas to disinfect water gradually decreased B-GAL activity at concentrations between 0 and 5600ppm for both the commercial and environmental enzymes. B-GAL from the environment behaved differently from its commercially available counterpart.
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- Date Issued: 2007