Institutions and economic research: a case of location externalities on agricultural resource allocation in the Kat River basin, South Africa. A Rejoinder
- Mbatha, Cyril N, Antrobus, Geoffrey G
- Authors: Mbatha, Cyril N , Antrobus, Geoffrey G
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143002 , vital:38184 , https://0-doi.org.wam.seals.ac.za/10.1080/03031853.2013.798069
- Description: In Mbatha and Antrobus (2008), an argument was put forward against an importation or adoption of universal models or general theorems to explain locally prevailing socio-economic conditions and predict outcomes in varied geographical contexts such as in the Kat River basin. In response to this argument a comment in this edition argues that our “results are caused by, metaphorically speaking, comparing apples and oranges. If, however, all of the relevant information is taken into account, a simple economic model may suffice to depict the situation within the KRV.” Here we illustrate that the comment comes from a misreading of basic details in the original discussion and in its construction and presentation of an alternative model of the KRV conditions the comment reiterates our original argument that general models and theorems are likely to fail to explain local intricacies primarily because they are not founded on local historical institutions.
- Full Text:
- Date Issued: 2013
- Authors: Mbatha, Cyril N , Antrobus, Geoffrey G
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143002 , vital:38184 , https://0-doi.org.wam.seals.ac.za/10.1080/03031853.2013.798069
- Description: In Mbatha and Antrobus (2008), an argument was put forward against an importation or adoption of universal models or general theorems to explain locally prevailing socio-economic conditions and predict outcomes in varied geographical contexts such as in the Kat River basin. In response to this argument a comment in this edition argues that our “results are caused by, metaphorically speaking, comparing apples and oranges. If, however, all of the relevant information is taken into account, a simple economic model may suffice to depict the situation within the KRV.” Here we illustrate that the comment comes from a misreading of basic details in the original discussion and in its construction and presentation of an alternative model of the KRV conditions the comment reiterates our original argument that general models and theorems are likely to fail to explain local intricacies primarily because they are not founded on local historical institutions.
- Full Text:
- Date Issued: 2013
A cooperative benefits framework in South Africa's land redistribution process: the case of sugarcane farmland transfers
- Mbatha, Cyril N, Antrobus, Geoffrey G
- Authors: Mbatha, Cyril N , Antrobus, Geoffrey G
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142922 , vital:38176 , DOI: 10.1080/03031853.2012.741207
- Description: A good indicator of successful land redistribution cases has to be the continuation of viable productivity rates in their post-transfer periods. Continued productivity benefits all the stakeholders that are involved in the process. Unfortunately, negative productivity levels have been reported in numerous South African land redistribution transfers in recent years. A game theoretic perspective is adopted to illustrate and argue that cooperation among key stakeholders, which could be enforced through long-term contracts between land buyers, sellers and new owners, may lead to maintenance and higher productivity levels and other benefits within the country's land redistribution process.
- Full Text:
- Date Issued: 2013
- Authors: Mbatha, Cyril N , Antrobus, Geoffrey G
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142922 , vital:38176 , DOI: 10.1080/03031853.2012.741207
- Description: A good indicator of successful land redistribution cases has to be the continuation of viable productivity rates in their post-transfer periods. Continued productivity benefits all the stakeholders that are involved in the process. Unfortunately, negative productivity levels have been reported in numerous South African land redistribution transfers in recent years. A game theoretic perspective is adopted to illustrate and argue that cooperation among key stakeholders, which could be enforced through long-term contracts between land buyers, sellers and new owners, may lead to maintenance and higher productivity levels and other benefits within the country's land redistribution process.
- Full Text:
- Date Issued: 2013
Synthesis and characterisation of oxorhenium(V) and tricarbonylrhenium(I) complexes with biologically active N, O and N, S-Donor ligands
- Authors: Mukiza, Janvier
- Date: 2013
- Subjects: Rhenium , Rhenium compounds , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10437 , http://hdl.handle.net/10948/d1020769
- Description: This study investigated the synthesis of rhenium(I) and rhenium(V) complexes with a variety of multidentate NS, NSO, NO and SO-donor ligands. It also investigated the synthesis of dinuclear dihalogeno- and trihalogeno-bridged rhenium(I) complexes based on the fac-[Re(CO)3]+ core. The reactions of hydrated folic acid with [Re(CO)5X] (X = Cl, Br) were studied, and the complexes [Re(CO)3(H2O)3]+[Re2(μ-X)3CO)6]−.5H2O [X= Br (1), Cl(2)] were isolated. The reaction of orotic acid potassium salt [Re(CO)5Br] was performed, and the complex [Re2(μ-Br)2(CO)8] was isolated. The reaction of bis(piperidin-1- yl)methanone with [Re(CO)5Cl] followed by recrystallisation of the resulting precipitate in dichloromethane/acetontrile resulted in the complex [Re2(μ- Cl)2(CO)6(MeCN)2]. The X-ray crystal structures show that all these complexes display a distorted octahedral geometry around the central rhenium atoms. The reactions of aroylhydrazone-based ligands such as 3-((pyridin- 2yl)methyleneamino)-2,3-dihydro-2-pyridin-2yl)quinazolin-4-(1H)-one (Hppq) and N-(di(pyridin-2-yl)methylene)benzohydrazide (Hdpmb) with [Re(CO)5Cl] were studied and led to the formation of the complexes [Re(CO)3Cl(Hdpmb)] and [Re(CO)3Cl(Hppq)]. The Hdpmb and Hppq coordinated to the fac-[Re(CO)3]+ core as neutral bidentate chalates via the pyridinic nitrogens (for Hdpmb) and via imino and pyridinic nitrogens for Hppq. The X-ray crystal structures show that the geometry around the rhenium in both complexes is a distorted octahedral. The treatment of the dithizone (H2dz) ligand with rhenium(V) precursors containing a triphenylphosphine group (PPh3) led to the decomposition of dithizone. The decomposition product reacted with the triphenylphosphine group and generated a new ligand triphenylphosphazeno-N-phenylmethanethiohydrazide (H2L). The reaction of trans-[ReOX3(PPh3)2] (X = Cl, Br) with dithizone (H2dz) led to the complex [ReO(dz)2][ReO(HL)2]. The reaction of trans-[ReOI2(OEt)(PPh3)2] with H2dz led to the same product. The reaction of cis-[ReO2I(PPh3)2] with H2dz in methanol led to [ReO(dz)2][ReO(HL)2](MeOH)2 in which methanol bonded to HLvia hydrogen bonds. The H2dz was doubly deprotonated and coordinated to the [ReO]3+ moiety via a thiolate sulfur and deprotonated hydrazinic nitrogen to yield [ReO(dz)2]−, while the H2L was singly deprotonated and coordinated to [ReO]3+ moiety via the neutral sulfur atom and deprotonated hydrazinic nitrogen to yield [ReO(HL)2]+. The X-ray crystal structure show that in both [ReO(HL)2]+ and [ReO(dz)2]−, the rhenium atoms are five-coordinated and adopt a distorted squarebased pyramidal geometry. The reaction of thiosemicarbazones such as salcylidene-4- phenylthiosemicarbazide (H3salpt) with cis-[ReO2I(PPh3)2] was investigated and led to the complex [ReO(Hsalpt)(H2salpt)]. The X-ray study reveals that Hsalpt is present as a tridentate chelate coordinating via the thiolate sulfur, imino nitrogen and phenolic oxygen, while H2salpt coordinates as a bidentate chelate via the thiolate sulfur and imino nitrogen atoms. The geometry around rhenium is distorted octahedral. The coordination mode of the benzoylthiourea derivatives 4-tert-butyl-N- (diphenylcarbamothioyl)benzamide (Htpb) and N-(diethylcarbamothioyl)benzamide (Heb) to the [Re2O3]4+ and fac-[Re(CO)3]+ cores were investigated. The reaction of [Re(CO)5Cl] in presence of sodium acetate with Htpb led to the dimeric complex [Re(CO)3(tpb)]2 in which the tpb coordinated to the fac-[Re(CO)3]+ core via the ketonic oxygen and bridging thiolate sulfur. The same reaction with Heb led to the monomeric complex [Re(CO)3(eb)(Heb)], in which the eb coordinates to the fac-[Re(CO)3]+core via thiolate sulfur and ketonic oxygen with Heb binding via the neutral sulfur atom. The reaction of Heb with cis-[ReO2I(PPh3)2] at room temperature with excess of sodium acetate led to the dimeric complex (μ-O)[ReO(eb)2]2 in which Heb is present as a monoanionic (deprotonated) bidentate with coordination through the thiolate sulfur and ketonic oxygen.
- Full Text:
- Date Issued: 2013
- Authors: Mukiza, Janvier
- Date: 2013
- Subjects: Rhenium , Rhenium compounds , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10437 , http://hdl.handle.net/10948/d1020769
- Description: This study investigated the synthesis of rhenium(I) and rhenium(V) complexes with a variety of multidentate NS, NSO, NO and SO-donor ligands. It also investigated the synthesis of dinuclear dihalogeno- and trihalogeno-bridged rhenium(I) complexes based on the fac-[Re(CO)3]+ core. The reactions of hydrated folic acid with [Re(CO)5X] (X = Cl, Br) were studied, and the complexes [Re(CO)3(H2O)3]+[Re2(μ-X)3CO)6]−.5H2O [X= Br (1), Cl(2)] were isolated. The reaction of orotic acid potassium salt [Re(CO)5Br] was performed, and the complex [Re2(μ-Br)2(CO)8] was isolated. The reaction of bis(piperidin-1- yl)methanone with [Re(CO)5Cl] followed by recrystallisation of the resulting precipitate in dichloromethane/acetontrile resulted in the complex [Re2(μ- Cl)2(CO)6(MeCN)2]. The X-ray crystal structures show that all these complexes display a distorted octahedral geometry around the central rhenium atoms. The reactions of aroylhydrazone-based ligands such as 3-((pyridin- 2yl)methyleneamino)-2,3-dihydro-2-pyridin-2yl)quinazolin-4-(1H)-one (Hppq) and N-(di(pyridin-2-yl)methylene)benzohydrazide (Hdpmb) with [Re(CO)5Cl] were studied and led to the formation of the complexes [Re(CO)3Cl(Hdpmb)] and [Re(CO)3Cl(Hppq)]. The Hdpmb and Hppq coordinated to the fac-[Re(CO)3]+ core as neutral bidentate chalates via the pyridinic nitrogens (for Hdpmb) and via imino and pyridinic nitrogens for Hppq. The X-ray crystal structures show that the geometry around the rhenium in both complexes is a distorted octahedral. The treatment of the dithizone (H2dz) ligand with rhenium(V) precursors containing a triphenylphosphine group (PPh3) led to the decomposition of dithizone. The decomposition product reacted with the triphenylphosphine group and generated a new ligand triphenylphosphazeno-N-phenylmethanethiohydrazide (H2L). The reaction of trans-[ReOX3(PPh3)2] (X = Cl, Br) with dithizone (H2dz) led to the complex [ReO(dz)2][ReO(HL)2]. The reaction of trans-[ReOI2(OEt)(PPh3)2] with H2dz led to the same product. The reaction of cis-[ReO2I(PPh3)2] with H2dz in methanol led to [ReO(dz)2][ReO(HL)2](MeOH)2 in which methanol bonded to HLvia hydrogen bonds. The H2dz was doubly deprotonated and coordinated to the [ReO]3+ moiety via a thiolate sulfur and deprotonated hydrazinic nitrogen to yield [ReO(dz)2]−, while the H2L was singly deprotonated and coordinated to [ReO]3+ moiety via the neutral sulfur atom and deprotonated hydrazinic nitrogen to yield [ReO(HL)2]+. The X-ray crystal structure show that in both [ReO(HL)2]+ and [ReO(dz)2]−, the rhenium atoms are five-coordinated and adopt a distorted squarebased pyramidal geometry. The reaction of thiosemicarbazones such as salcylidene-4- phenylthiosemicarbazide (H3salpt) with cis-[ReO2I(PPh3)2] was investigated and led to the complex [ReO(Hsalpt)(H2salpt)]. The X-ray study reveals that Hsalpt is present as a tridentate chelate coordinating via the thiolate sulfur, imino nitrogen and phenolic oxygen, while H2salpt coordinates as a bidentate chelate via the thiolate sulfur and imino nitrogen atoms. The geometry around rhenium is distorted octahedral. The coordination mode of the benzoylthiourea derivatives 4-tert-butyl-N- (diphenylcarbamothioyl)benzamide (Htpb) and N-(diethylcarbamothioyl)benzamide (Heb) to the [Re2O3]4+ and fac-[Re(CO)3]+ cores were investigated. The reaction of [Re(CO)5Cl] in presence of sodium acetate with Htpb led to the dimeric complex [Re(CO)3(tpb)]2 in which the tpb coordinated to the fac-[Re(CO)3]+ core via the ketonic oxygen and bridging thiolate sulfur. The same reaction with Heb led to the monomeric complex [Re(CO)3(eb)(Heb)], in which the eb coordinates to the fac-[Re(CO)3]+core via thiolate sulfur and ketonic oxygen with Heb binding via the neutral sulfur atom. The reaction of Heb with cis-[ReO2I(PPh3)2] at room temperature with excess of sodium acetate led to the dimeric complex (μ-O)[ReO(eb)2]2 in which Heb is present as a monoanionic (deprotonated) bidentate with coordination through the thiolate sulfur and ketonic oxygen.
- Full Text:
- Date Issued: 2013
Rhenium (I), (III) and (V) complexes with potentially multidentate N, O-Donor ligands
- Authors: Habarurema, Gratien
- Date: 2013
- Subjects: Rhenium , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10441 , http://hdl.handle.net/10948/d1020952
- Description: This study investigates the coordination modes of potential multidentate N,O-donor Schiff base ligands to the [ReVO]3+ and fac-[ReI(CO)3]+ cores. The project is aimed at the synthesis of tridentate, tetradentate and pentadentate Schiff bases ligands derived from the condensation reactions of benzaldehyde with different primary amines. The structures of these Schiff bases and their complexes were confirmed by using physical characterization methods, namely melting points, UV-Visible, UV-emission, 1H NMR and IR spectroscopy, X-ray diffractometry and elemental analysis. To further understand the coordination chemistry of rhenium, the prepared diiminediphenol N2O2-donor Schiff base ligand N N′-o-phenylene-bis(salicylaldimine) (H2salphen) was reacted with trans-[ReOCl3(PPh3)2] to yield cis-[ReCl2(ophsal)(PPh3)], whereas its reaction with trans-[ReOBr3(PPh3)2] resulted in the formation of the cis-[ReBr2(aphsal)(PPh3)].2CH3CN complex. In the above complexes the H2salphen ligand was cleaved leading to the coordinated tridentate ophsal NO2- and aphsal N2O-donor ligands. The reaction of H3aphsal with trans-[ReOBr3(PPh3)2] in toluene led to an unexpected compound, trans- [{[ReBr(aphsal)(PPh3)2]Br}{[ReBr(aphsal)(PPh3)2](ReO4)}] with an imido [ReNR]3+core. The ligand aphsal was coordinated tridentately with the doubly deprotonated amino nitrogen leading to Re(V)-imido complexes. The reaction of 2-((Z)-(2-aminoethylimino)methyl)phenol (H3amphol) with [Re(CO)5Cl] led to the rhenium(I) product fac-[Re(CO)3(H3amphol)] with H3amphol coordinated as a monoanionic tridentate chelate through its phenolate oxygen and amino nitrogen atoms. The X-ray crystal structures showed that all complexes display a distorted octahedral geometry around the central rhenium atom. The reaction of 2,6-bis(2-hydroxyphenylimino)pyridine (H2hpp) with cis-[ReO2I(PPh3)2] resulted in the reduced Re(III) product trans-[Re(hpp)(PPh3)2]I, while trans-[Re(hpp)(PPh3)2](ReO4) was isolated from its reaction with trans-[ReOCl3(PPh3)2]. The H2hpp ligand acts as a pentadentate N3O2-donor ligand where the two phenolic protons undergo deprotonation and its three nitrogens act as neutral donor atoms. Both compounds resulted from a disproportionation reaction characterized by the produced perrhenate counter-ion. The complex fac-[Re(CO)3(H2hpp)Cl] was prepared from [Re(CO)5Cl] and H2hpp in toluene. The H2hpp ligand acted as a neutral bidentate N,N-donor chelate. The metal is coordinated to three carbonyl donors in a facial orientation, two neutral nitrogen atoms and a chloride ligand. The reactions of the potentially tetradentate ligand N,N'-ethylenebis(salicylideneimine) (H2salen) with different rhenium(V) precursors resulted in the formation of two dimeric oxorhenium (V) compounds. In the reaction of H2salen with trans-[ReOCl3(PPh3)2] in ethanol, the highly unusual distorted dimeric complex (μ-salen)[ReOCl2(PPh3)]2 was isolated, in which salen2- is coordinated as a tetradentate to two oxorhenium(V) centres, and salen2- is present as a bidentate monoanionic ligand on each rhenium center. The reaction of cis- [ReO2I(PPh3)2] with H2salen led to the formation of the neutral dimeric oxorhenium(V) complex (μ-O)[ReO(salen)]2 in which the tetradentate chelate salen acts as a tetradentate dianionic ligand through its phenolate oxygens and nitrogen atoms of the azomethine groups. In its reaction with H2hmp the compound (μ-O)[ReO(hmp)]2 was isolated. In this product the pentadentate ligand H2hmp coordinated as tetradentate via its phenolic oxygen and nitrogen atoms. The reaction of the potentially tetradentate N1,N2-bis(aminobenzylidene)-1,2-ethylenediamine (H2amben) with trans-[ReOCl3(PPh3)2] led to the formation of the monocationic square-pyramidal complex salt [ReO(amben)](ReO4.
- Full Text:
- Date Issued: 2013
- Authors: Habarurema, Gratien
- Date: 2013
- Subjects: Rhenium , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10441 , http://hdl.handle.net/10948/d1020952
- Description: This study investigates the coordination modes of potential multidentate N,O-donor Schiff base ligands to the [ReVO]3+ and fac-[ReI(CO)3]+ cores. The project is aimed at the synthesis of tridentate, tetradentate and pentadentate Schiff bases ligands derived from the condensation reactions of benzaldehyde with different primary amines. The structures of these Schiff bases and their complexes were confirmed by using physical characterization methods, namely melting points, UV-Visible, UV-emission, 1H NMR and IR spectroscopy, X-ray diffractometry and elemental analysis. To further understand the coordination chemistry of rhenium, the prepared diiminediphenol N2O2-donor Schiff base ligand N N′-o-phenylene-bis(salicylaldimine) (H2salphen) was reacted with trans-[ReOCl3(PPh3)2] to yield cis-[ReCl2(ophsal)(PPh3)], whereas its reaction with trans-[ReOBr3(PPh3)2] resulted in the formation of the cis-[ReBr2(aphsal)(PPh3)].2CH3CN complex. In the above complexes the H2salphen ligand was cleaved leading to the coordinated tridentate ophsal NO2- and aphsal N2O-donor ligands. The reaction of H3aphsal with trans-[ReOBr3(PPh3)2] in toluene led to an unexpected compound, trans- [{[ReBr(aphsal)(PPh3)2]Br}{[ReBr(aphsal)(PPh3)2](ReO4)}] with an imido [ReNR]3+core. The ligand aphsal was coordinated tridentately with the doubly deprotonated amino nitrogen leading to Re(V)-imido complexes. The reaction of 2-((Z)-(2-aminoethylimino)methyl)phenol (H3amphol) with [Re(CO)5Cl] led to the rhenium(I) product fac-[Re(CO)3(H3amphol)] with H3amphol coordinated as a monoanionic tridentate chelate through its phenolate oxygen and amino nitrogen atoms. The X-ray crystal structures showed that all complexes display a distorted octahedral geometry around the central rhenium atom. The reaction of 2,6-bis(2-hydroxyphenylimino)pyridine (H2hpp) with cis-[ReO2I(PPh3)2] resulted in the reduced Re(III) product trans-[Re(hpp)(PPh3)2]I, while trans-[Re(hpp)(PPh3)2](ReO4) was isolated from its reaction with trans-[ReOCl3(PPh3)2]. The H2hpp ligand acts as a pentadentate N3O2-donor ligand where the two phenolic protons undergo deprotonation and its three nitrogens act as neutral donor atoms. Both compounds resulted from a disproportionation reaction characterized by the produced perrhenate counter-ion. The complex fac-[Re(CO)3(H2hpp)Cl] was prepared from [Re(CO)5Cl] and H2hpp in toluene. The H2hpp ligand acted as a neutral bidentate N,N-donor chelate. The metal is coordinated to three carbonyl donors in a facial orientation, two neutral nitrogen atoms and a chloride ligand. The reactions of the potentially tetradentate ligand N,N'-ethylenebis(salicylideneimine) (H2salen) with different rhenium(V) precursors resulted in the formation of two dimeric oxorhenium (V) compounds. In the reaction of H2salen with trans-[ReOCl3(PPh3)2] in ethanol, the highly unusual distorted dimeric complex (μ-salen)[ReOCl2(PPh3)]2 was isolated, in which salen2- is coordinated as a tetradentate to two oxorhenium(V) centres, and salen2- is present as a bidentate monoanionic ligand on each rhenium center. The reaction of cis- [ReO2I(PPh3)2] with H2salen led to the formation of the neutral dimeric oxorhenium(V) complex (μ-O)[ReO(salen)]2 in which the tetradentate chelate salen acts as a tetradentate dianionic ligand through its phenolate oxygens and nitrogen atoms of the azomethine groups. In its reaction with H2hmp the compound (μ-O)[ReO(hmp)]2 was isolated. In this product the pentadentate ligand H2hmp coordinated as tetradentate via its phenolic oxygen and nitrogen atoms. The reaction of the potentially tetradentate N1,N2-bis(aminobenzylidene)-1,2-ethylenediamine (H2amben) with trans-[ReOCl3(PPh3)2] led to the formation of the monocationic square-pyramidal complex salt [ReO(amben)](ReO4.
- Full Text:
- Date Issued: 2013
Synthesis of fluorescent polymers with pendant triazole-substituted coumarin side-chains via a combination of click chemistry and raft-mediated polymerization
- Authors: Wali, Nwabisa Whitney
- Date: 2013
- Subjects: Fluorescent polymers , Polymerization , Macromolecules -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10432 , http://hdl.handle.net/10948/d1020142
- Description: This research project focuses on the synthesis of fluorescent polymers with pendant triazole-substituted coumarin side chain units. Copper(I)-catalyzed Huisgen’s 1,3-dipolar cycloaddition of alkynes with azides to form a 1,2,3-triazole ring, a typical example of “click” reaction, has been utilized for the synthesis of a novel vinyl monomer, 2-oxo-3-(4- vinyl-1H-1,2,3-triazol-1-yl)-2H-chromen-7-yl acetate 62. The monomer and its precursors were synthesised and characterized using 1D- and 2D-NMR and FT-IR. Coumarin-containing triazole polymers were synthesised using free radical polymerization. Reversible Addition-Fragmentation Chain Transfer (RAFT)-mediated polymerization was used to synthesise well defined coumarin-containing triazole polymers with moderate PDI values. The polymers were characterised using 1H-NMR and FT-IR. Modelling of the monomer precursor 61 and the monomer 62 at DFT level of approximation provided useful insights into possible conformations adopted by the monomer precursor 61 and the monomer 62. The photophysical properties of the novel monomer and the synthesised polymers were investigated in a polar solvent.
- Full Text:
- Date Issued: 2013
- Authors: Wali, Nwabisa Whitney
- Date: 2013
- Subjects: Fluorescent polymers , Polymerization , Macromolecules -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10432 , http://hdl.handle.net/10948/d1020142
- Description: This research project focuses on the synthesis of fluorescent polymers with pendant triazole-substituted coumarin side chain units. Copper(I)-catalyzed Huisgen’s 1,3-dipolar cycloaddition of alkynes with azides to form a 1,2,3-triazole ring, a typical example of “click” reaction, has been utilized for the synthesis of a novel vinyl monomer, 2-oxo-3-(4- vinyl-1H-1,2,3-triazol-1-yl)-2H-chromen-7-yl acetate 62. The monomer and its precursors were synthesised and characterized using 1D- and 2D-NMR and FT-IR. Coumarin-containing triazole polymers were synthesised using free radical polymerization. Reversible Addition-Fragmentation Chain Transfer (RAFT)-mediated polymerization was used to synthesise well defined coumarin-containing triazole polymers with moderate PDI values. The polymers were characterised using 1H-NMR and FT-IR. Modelling of the monomer precursor 61 and the monomer 62 at DFT level of approximation provided useful insights into possible conformations adopted by the monomer precursor 61 and the monomer 62. The photophysical properties of the novel monomer and the synthesised polymers were investigated in a polar solvent.
- Full Text:
- Date Issued: 2013
Photophysicochemical properties of aluminium phthalocyanine-platinum conjugates
- Authors: Malinga, Nduduzo Nkanyiso
- Date: 2013 , 2013-04-05
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4285 , http://hdl.handle.net/10962/d1002954 , Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Description: The combination of chemotherapy and photodynamic therapy was investigated by synthesis and characterization of octacarboxy phthalocyanine covalent conjugates with platinum complexes. This work presents the synthesis, characterization and photophysicochemical properties of aluminium (diaquaplatinum) octacarboxyphthalocyanine and aluminium (diammine) octacarboxyphthalocyanine. The conjugates were prepared by conjugating aluminium octacarboxy phthalocyanine with potassium tetrachloro platinate to yield aluminium tetrakis and trikis (diaquaplatinum) octacarboxy phthalocyanine. The aluminium octacarboxy phthalocyanine was also conjugated with cis-diamminedichloroplatinum to yield aluminium bis and tris (diaquaplatinum) octacarboxy phthalocyanine. From the characterization of the conjugates it was discovered that the aluminium (diaquaplatinum) octacarboxy phthalocyanine had formed platinum nanoparticles with the Pc acting as a capping agent. The triplet lifetimes decreased with the increasing number of platinum complexesconjugated to the Pc. The heavy atom effect improved the overall photophysicochemical properties.
- Full Text:
- Date Issued: 2013
- Authors: Malinga, Nduduzo Nkanyiso
- Date: 2013 , 2013-04-05
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4285 , http://hdl.handle.net/10962/d1002954 , Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Description: The combination of chemotherapy and photodynamic therapy was investigated by synthesis and characterization of octacarboxy phthalocyanine covalent conjugates with platinum complexes. This work presents the synthesis, characterization and photophysicochemical properties of aluminium (diaquaplatinum) octacarboxyphthalocyanine and aluminium (diammine) octacarboxyphthalocyanine. The conjugates were prepared by conjugating aluminium octacarboxy phthalocyanine with potassium tetrachloro platinate to yield aluminium tetrakis and trikis (diaquaplatinum) octacarboxy phthalocyanine. The aluminium octacarboxy phthalocyanine was also conjugated with cis-diamminedichloroplatinum to yield aluminium bis and tris (diaquaplatinum) octacarboxy phthalocyanine. From the characterization of the conjugates it was discovered that the aluminium (diaquaplatinum) octacarboxy phthalocyanine had formed platinum nanoparticles with the Pc acting as a capping agent. The triplet lifetimes decreased with the increasing number of platinum complexesconjugated to the Pc. The heavy atom effect improved the overall photophysicochemical properties.
- Full Text:
- Date Issued: 2013
Novel applications of Morita-Baylis-Hillman methodology in organic synthesis
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
- Date Issued: 2013
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
- Date Issued: 2013
Biochemical characterisation of Pfj2, a Plasmodium falciparum heat shock protein 40 chaperone potentially involved in protein quality control in the endoplasmic reticulum
- Authors: Afolayan, Omolola Folasade
- Date: 2013
- Subjects: Plasmodium falciparum Endoplasmic reticulum Heat shock proteins Malaria , Mosquito-borne infectious disease
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3883 , http://hdl.handle.net/10962/d1001617
- Description: Plasmodium falciparum is a protozoan parasite that causes a severe form of malaria, a mosquito-borne infectious disease in humans. P. falciparum encodes a number of proteins to facilitate its life-cycle, including a type II heat shock protein 40 (Hsp40), Pfj2. Pfj2 shows a degree of homology to human ERdj5, a resident protein of the endoplasmic reticulum (ER) that promotes protein quality control by facilitating the degradation of misfolded proteins. The overall aim of this study was to further understand the function of Pfj2 in the P. falciparum cell by characterising it biochemically. A bioinformatic analysis of Pfj2 was carried out to enable the identification of a potential ER signal sequence and cleavage site. Furthermore, an analysis of Pfj2 protein sequence was performed to compare domain similarities and identities with typical type II Hsp40s namely, human ERdj5, S. cerevisiae Sis1, human Hsj1a and human DnaJB4. The method used included the insertion of the codon-optimised coding sequence for the processed ER form of Pfj2 into the prokaryotic expression vector, pQE30, to enable overproduction of a histidine-tagged protein. A 62 kDa His₆-Pfj2 was successfully expressed in Escherichia coli and purified using denaturing nickel affinity chromatography. ATPase assays were performed to determine the ability of His₆- Pfj2 to stimulate the chaperone activity of the ER Hsp70, also called immunoglobulin binding protein (BiP). Initial studies were conducted on readily available mammalian His₆-BiP as a control, which was shown to have an intrinsic activity of 12.07±3.92 nmolPi/min/mg. His₆- Pfj2 did not stimulate the ATPase activity of mammalian His₆-BiP, suggesting that it either could not act as a co-chaperone of mammalian His₆-BiP (specificity), or it required a misfolded substrate in the system. Therefore, ongoing studies are addressing the interaction of Pfj2 and misfolded substrates with P. falciparum BiP. The results of these studies will further our understanding of a poorly-studied parasite chaperone that represents a potential drug target for development of novel strategies for the control of a serious human disease
- Full Text:
- Date Issued: 2013
- Authors: Afolayan, Omolola Folasade
- Date: 2013
- Subjects: Plasmodium falciparum Endoplasmic reticulum Heat shock proteins Malaria , Mosquito-borne infectious disease
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3883 , http://hdl.handle.net/10962/d1001617
- Description: Plasmodium falciparum is a protozoan parasite that causes a severe form of malaria, a mosquito-borne infectious disease in humans. P. falciparum encodes a number of proteins to facilitate its life-cycle, including a type II heat shock protein 40 (Hsp40), Pfj2. Pfj2 shows a degree of homology to human ERdj5, a resident protein of the endoplasmic reticulum (ER) that promotes protein quality control by facilitating the degradation of misfolded proteins. The overall aim of this study was to further understand the function of Pfj2 in the P. falciparum cell by characterising it biochemically. A bioinformatic analysis of Pfj2 was carried out to enable the identification of a potential ER signal sequence and cleavage site. Furthermore, an analysis of Pfj2 protein sequence was performed to compare domain similarities and identities with typical type II Hsp40s namely, human ERdj5, S. cerevisiae Sis1, human Hsj1a and human DnaJB4. The method used included the insertion of the codon-optimised coding sequence for the processed ER form of Pfj2 into the prokaryotic expression vector, pQE30, to enable overproduction of a histidine-tagged protein. A 62 kDa His₆-Pfj2 was successfully expressed in Escherichia coli and purified using denaturing nickel affinity chromatography. ATPase assays were performed to determine the ability of His₆- Pfj2 to stimulate the chaperone activity of the ER Hsp70, also called immunoglobulin binding protein (BiP). Initial studies were conducted on readily available mammalian His₆-BiP as a control, which was shown to have an intrinsic activity of 12.07±3.92 nmolPi/min/mg. His₆- Pfj2 did not stimulate the ATPase activity of mammalian His₆-BiP, suggesting that it either could not act as a co-chaperone of mammalian His₆-BiP (specificity), or it required a misfolded substrate in the system. Therefore, ongoing studies are addressing the interaction of Pfj2 and misfolded substrates with P. falciparum BiP. The results of these studies will further our understanding of a poorly-studied parasite chaperone that represents a potential drug target for development of novel strategies for the control of a serious human disease
- Full Text:
- Date Issued: 2013
Fixed points of single-valued and multi-valued mappings with applications
- Authors: Stofile, Simfumene
- Date: 2013
- Subjects: Fixed point theory Mappings (Mathematics) Coincidence theory (Mathematics) Metric spaces Uniform spaces Set-valued maps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5397 , http://hdl.handle.net/10962/d1002960
- Description: The relationship between the convergence of a sequence of self mappings of a metric space and their fixed points, known as the stability (or continuity) of fixed points has been of continuing interest and widely studied in fixed point theory. In this thesis we study the stability of common fixed points in a Hausdorff uniform space whose uniformity is generated by a family of pseudometrics, by using some general notations of convergence. These results are then extended to 2-metric spaces due to S. Gähler. In addition, a well-known theorem of T. Suzuki that generalized the Banach Contraction Principle is also extended to 2-metric spaces and applied to obtain a coincidence theorem for a pair of mappings on an arbitrary set with values in a 2-metric space. Further, we prove the existence of coincidence and fixed points of Ćirić type weakly generalized contractions in metric spaces. Subsequently, the above result is utilized to discuss applications to the convergence of modified Mann and Ishikawa iterations in a convex metric space. Finally, we obtain coincidence, fixed and stationary point results for multi-valued and hybrid pairs of mappings on a metric space.
- Full Text:
- Date Issued: 2013
- Authors: Stofile, Simfumene
- Date: 2013
- Subjects: Fixed point theory Mappings (Mathematics) Coincidence theory (Mathematics) Metric spaces Uniform spaces Set-valued maps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5397 , http://hdl.handle.net/10962/d1002960
- Description: The relationship between the convergence of a sequence of self mappings of a metric space and their fixed points, known as the stability (or continuity) of fixed points has been of continuing interest and widely studied in fixed point theory. In this thesis we study the stability of common fixed points in a Hausdorff uniform space whose uniformity is generated by a family of pseudometrics, by using some general notations of convergence. These results are then extended to 2-metric spaces due to S. Gähler. In addition, a well-known theorem of T. Suzuki that generalized the Banach Contraction Principle is also extended to 2-metric spaces and applied to obtain a coincidence theorem for a pair of mappings on an arbitrary set with values in a 2-metric space. Further, we prove the existence of coincidence and fixed points of Ćirić type weakly generalized contractions in metric spaces. Subsequently, the above result is utilized to discuss applications to the convergence of modified Mann and Ishikawa iterations in a convex metric space. Finally, we obtain coincidence, fixed and stationary point results for multi-valued and hybrid pairs of mappings on a metric space.
- Full Text:
- Date Issued: 2013
Low symmetry metallophthalocyanines and their nanoparticle conjugates for photodynamic antimicrobial chemotherapy
- Authors: Masilela, Nkosiphile
- Date: 2013
- Subjects: Nanoparticles Anti-infective agents Chemotherapy Photochemotherapy Quantum dots Gold Silver , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4278 , http://hdl.handle.net/10962/d1001906
- Description: This thesis reports on the syntheses of novel low symmetrically substituted Zn, Sn, Ge and Ti MPc complexes containing a single carboxylic or cysteinyl group available for attachments to MNPs. The complexes were extensively characterized by various techniques to ensure their purity. Various metallic nanoparticles consisting of silver (AgNPs), gold (AuNPs) as well as quantum dots (QDs) were successfully prepared and conjugated to the low symmetry phthalocyanine complexes. The conjugates were successfully characterized using many techniques. The Q-band maxima of the MPcs were observed at completely different wavelength regions depending on the nature of the substituents and the central metal used. Blue shifting of the Q band in the absorption spectra was observed for the complexes in the presence of AuNPs, while aggregation was observed in the presence of quantum dots. The complexes were successfully electrospun into polymer fibers for the antimicrobial inhibition of bacteria. The photophysical and photochemical properties of these complexes were extensively investigated. Higher triplet and singlet oxygen quantum yields were achieved for the Ge Pc complexes, with all the complexes giving reasonable singlet oxygen quantum yields. An enhancement in triplet and singlet oxygen quantum yields was observed for all the complexes in the presence of metal nanoparticles. However, the singlet oxygen quantum yields decreased for all the complexes when incorporated into electrospun fibers. The antimicrobial behaviour of the complexes was investigated against Bacillus Subtilis and Staphylococcus Aureus in solution and in the fiber matrix. High antimicrobial inhibitions were observed for the Ge complexes followed by the ZnPc derivatives. All the low symmetry ZnPc derivatives were conjugated to AgNPs and their antimicrobial behaviour was compared to their symmetrical counterparts. The best antimicrobial inhibition behaviour was observed for the low symmetry Pcs when compared to their symmetrical counterparts. In the absence and in the presence of AgNPs, axially ligated SiPc also showed better antimicrobial activity when it was compared to the unsubstituted ZnPc complex.
- Full Text:
- Date Issued: 2013
- Authors: Masilela, Nkosiphile
- Date: 2013
- Subjects: Nanoparticles Anti-infective agents Chemotherapy Photochemotherapy Quantum dots Gold Silver , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4278 , http://hdl.handle.net/10962/d1001906
- Description: This thesis reports on the syntheses of novel low symmetrically substituted Zn, Sn, Ge and Ti MPc complexes containing a single carboxylic or cysteinyl group available for attachments to MNPs. The complexes were extensively characterized by various techniques to ensure their purity. Various metallic nanoparticles consisting of silver (AgNPs), gold (AuNPs) as well as quantum dots (QDs) were successfully prepared and conjugated to the low symmetry phthalocyanine complexes. The conjugates were successfully characterized using many techniques. The Q-band maxima of the MPcs were observed at completely different wavelength regions depending on the nature of the substituents and the central metal used. Blue shifting of the Q band in the absorption spectra was observed for the complexes in the presence of AuNPs, while aggregation was observed in the presence of quantum dots. The complexes were successfully electrospun into polymer fibers for the antimicrobial inhibition of bacteria. The photophysical and photochemical properties of these complexes were extensively investigated. Higher triplet and singlet oxygen quantum yields were achieved for the Ge Pc complexes, with all the complexes giving reasonable singlet oxygen quantum yields. An enhancement in triplet and singlet oxygen quantum yields was observed for all the complexes in the presence of metal nanoparticles. However, the singlet oxygen quantum yields decreased for all the complexes when incorporated into electrospun fibers. The antimicrobial behaviour of the complexes was investigated against Bacillus Subtilis and Staphylococcus Aureus in solution and in the fiber matrix. High antimicrobial inhibitions were observed for the Ge complexes followed by the ZnPc derivatives. All the low symmetry ZnPc derivatives were conjugated to AgNPs and their antimicrobial behaviour was compared to their symmetrical counterparts. The best antimicrobial inhibition behaviour was observed for the low symmetry Pcs when compared to their symmetrical counterparts. In the absence and in the presence of AgNPs, axially ligated SiPc also showed better antimicrobial activity when it was compared to the unsubstituted ZnPc complex.
- Full Text:
- Date Issued: 2013
Synthesis and characterization of metal sulfide nanoparticles/polymer nanocomposites
- Authors: Mbese, Johannes Zanoxolo
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11344 , http://hdl.handle.net/10353/d1016190
- Description: The focus of this project was to synthesize and characterize metal sulfide nanoparticles /polymer nanocomposites. The work involved the synthesis of dithiocarbamato ligands and complexes derived from aniline. Zn(II), Cd(II) and Hg(II) dithiocarbamato complexes were used as single-molecule precursors for the synthesis of the ZnS, CdS and HgS nanoparticles and their optical and structural properties studied. The other focus of this work was to synthesize a combined functionality metal sulfide nanoparticles/polymer nanocomposites by dispersing as-synthesized ZnS, CdS and HgS nanoparticles in polymethyl methacrylate (PMMA) matrix. The characterization of the ligands, complexes, nanoparticles and nanocomposites were investigated using relevant instrumental tools like UV-Vis, photoluminescence (PL), Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersion X-ray (EDX), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
- Full Text:
- Date Issued: 2013
- Authors: Mbese, Johannes Zanoxolo
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11344 , http://hdl.handle.net/10353/d1016190
- Description: The focus of this project was to synthesize and characterize metal sulfide nanoparticles /polymer nanocomposites. The work involved the synthesis of dithiocarbamato ligands and complexes derived from aniline. Zn(II), Cd(II) and Hg(II) dithiocarbamato complexes were used as single-molecule precursors for the synthesis of the ZnS, CdS and HgS nanoparticles and their optical and structural properties studied. The other focus of this work was to synthesize a combined functionality metal sulfide nanoparticles/polymer nanocomposites by dispersing as-synthesized ZnS, CdS and HgS nanoparticles in polymethyl methacrylate (PMMA) matrix. The characterization of the ligands, complexes, nanoparticles and nanocomposites were investigated using relevant instrumental tools like UV-Vis, photoluminescence (PL), Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersion X-ray (EDX), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
- Full Text:
- Date Issued: 2013
Species and spatio-temporal variation in the yield, nutritive value and in vitro ruminal fermentation characteristics of selected grass species from two communal grazing lands of the Eastern Cape
- Authors: Kwaza, Ayanda
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc Agric (Pasture Science)
- Identifier: http://hdl.handle.net/10353/987 , vital:26515
- Description: Communal rangelands sustain a large proportion of the livestock in South Africa. A few dominant grass species contribute to the bulk of the livestock forage in these rangelands. Little is known on the chemical composition and in vitro ruminal fermentation characteristics of grass species grazed by ruminants in the communal grazing lands of Eastern Cape Province in South Africa. The objectives of this study were therefore to investigate seasonal and altitudinal variations in biomass yield, chemical composition, and in vitro ruminal degradability and cumulative gas production of selected (dominant) grass species. The grass species were collected over four seasons (summer, autumn, winter and spring) from three altitudes/landscape gradients (upland, gentle sloppy and bottomlands) across two communal areas (Hala in highland (Highveld) and Gqumashe in lowland (Lowveld)) of the Eastern Cape province, South Africa. In each altitude, three 50 m x 20 m plots, which served as replicates were marked to collect vegetation samples. A 5 x 4 x 3 factorial experiment in a randomised complete block design was used with season, altitude and grass species being the main factors, and with the plots within altitudes serving as blocks (replicates). Data analysis was done separately for the two communal study areas using the General Linear Models (GLM) procedure of SAS to test differences between species, seasons and altitudes. The common grass species in both grazing lands were Cynodon dactylon, Eragrostis chloromelus, Eragrostis plana, Sporobolus africanus and Themeda triandra. When the DM yield of all the grasses was combined, the results showed a generally low forage dry matter yield during the dry season. There was no significant (P>0.05) interaction between any of the main factors. Macro and micro mineral content of plant samples collected from the two communal grazing lands showed great variations (P<0.05) between species, seasons and altitude. In the Highveld, CP ranged from 3.9 to 6.5% DM being significantly highest (P<0.05) in Cynodon dactylon and lowest in E. plana. When all species were combined, higher CP was recorded for samples harvested in summer (5.5%) followed by spring and autumn, and lowest in winter (3.8%). In the Lowveld, Eragrostis chloromelus had higher (P<0.05) CP level followed by C. dactylon and T. Triandra. When all species were pooled, forage samples harvested in summer had a significantly higher (P<0.05) CP followed by spring, autumn and winter. In summary, CP content of all grasses was below the critical maintenance level for livestock especially during late dry seasons. In both areas, the highest NDF level was measured for Eragrostis plana and lowest for Themeda triandra. As for altitudinal differences, samples collected from the upland areas had generally the lowest (P<0.05) CP and highest ADF contents. For grasses harvested from the Highveld, C. dactylon produced the most (P<0.05) gas after 48 h of fermentation (794.6 ml/g DM) and also had the highest 48h DMD (415.1 g kg-1). Themeda triandra produced least (P<0.05) gas (742 ml/g DM) 48h post-incubation. The least (P<0.05) degradable species after 48 h was E. chloromelus (372.9 g kg-1). For grasses harvested from Lowveld, the 48h cumulative gas production was highest (822.7 ml/g DM) in E. plana and lowest (742.8 ml/g DM) in E. chloromelus, while S. africanus had least 48h DMD (327.9 kg-1). In both the Highveld and Lowveld, gas production and DMD were highest in the autumn season. It was concluded most grasses were deficient in calcium, magnesium, phosphorus and potassium. Therefore, it is recommended that mineral supplements should be offered to animals to improve animal productivity throughout the year. Findings of this study suggested that addition of protein and energy sources may be desirable in both grazing areas to meet the maintenance/production requirements of the grazing ruminants throughout the year. Key words: Forage yield, chemical composition, landscape gradient; seasonal variations; in vitro ruminal gas production; dry matter degradability.
- Full Text:
- Date Issued: 2013
- Authors: Kwaza, Ayanda
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc Agric (Pasture Science)
- Identifier: http://hdl.handle.net/10353/987 , vital:26515
- Description: Communal rangelands sustain a large proportion of the livestock in South Africa. A few dominant grass species contribute to the bulk of the livestock forage in these rangelands. Little is known on the chemical composition and in vitro ruminal fermentation characteristics of grass species grazed by ruminants in the communal grazing lands of Eastern Cape Province in South Africa. The objectives of this study were therefore to investigate seasonal and altitudinal variations in biomass yield, chemical composition, and in vitro ruminal degradability and cumulative gas production of selected (dominant) grass species. The grass species were collected over four seasons (summer, autumn, winter and spring) from three altitudes/landscape gradients (upland, gentle sloppy and bottomlands) across two communal areas (Hala in highland (Highveld) and Gqumashe in lowland (Lowveld)) of the Eastern Cape province, South Africa. In each altitude, three 50 m x 20 m plots, which served as replicates were marked to collect vegetation samples. A 5 x 4 x 3 factorial experiment in a randomised complete block design was used with season, altitude and grass species being the main factors, and with the plots within altitudes serving as blocks (replicates). Data analysis was done separately for the two communal study areas using the General Linear Models (GLM) procedure of SAS to test differences between species, seasons and altitudes. The common grass species in both grazing lands were Cynodon dactylon, Eragrostis chloromelus, Eragrostis plana, Sporobolus africanus and Themeda triandra. When the DM yield of all the grasses was combined, the results showed a generally low forage dry matter yield during the dry season. There was no significant (P>0.05) interaction between any of the main factors. Macro and micro mineral content of plant samples collected from the two communal grazing lands showed great variations (P<0.05) between species, seasons and altitude. In the Highveld, CP ranged from 3.9 to 6.5% DM being significantly highest (P<0.05) in Cynodon dactylon and lowest in E. plana. When all species were combined, higher CP was recorded for samples harvested in summer (5.5%) followed by spring and autumn, and lowest in winter (3.8%). In the Lowveld, Eragrostis chloromelus had higher (P<0.05) CP level followed by C. dactylon and T. Triandra. When all species were pooled, forage samples harvested in summer had a significantly higher (P<0.05) CP followed by spring, autumn and winter. In summary, CP content of all grasses was below the critical maintenance level for livestock especially during late dry seasons. In both areas, the highest NDF level was measured for Eragrostis plana and lowest for Themeda triandra. As for altitudinal differences, samples collected from the upland areas had generally the lowest (P<0.05) CP and highest ADF contents. For grasses harvested from the Highveld, C. dactylon produced the most (P<0.05) gas after 48 h of fermentation (794.6 ml/g DM) and also had the highest 48h DMD (415.1 g kg-1). Themeda triandra produced least (P<0.05) gas (742 ml/g DM) 48h post-incubation. The least (P<0.05) degradable species after 48 h was E. chloromelus (372.9 g kg-1). For grasses harvested from Lowveld, the 48h cumulative gas production was highest (822.7 ml/g DM) in E. plana and lowest (742.8 ml/g DM) in E. chloromelus, while S. africanus had least 48h DMD (327.9 kg-1). In both the Highveld and Lowveld, gas production and DMD were highest in the autumn season. It was concluded most grasses were deficient in calcium, magnesium, phosphorus and potassium. Therefore, it is recommended that mineral supplements should be offered to animals to improve animal productivity throughout the year. Findings of this study suggested that addition of protein and energy sources may be desirable in both grazing areas to meet the maintenance/production requirements of the grazing ruminants throughout the year. Key words: Forage yield, chemical composition, landscape gradient; seasonal variations; in vitro ruminal gas production; dry matter degradability.
- Full Text:
- Date Issued: 2013
Form over function? The practical application of the Recognition of Customary Marriages Act 1998 in South Africa
- Authors: Kruuse, Helen
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54094 , vital:26389 , http://journals.co.za/content/ju_jur/2013/1/EJC148455
- Description: The Recognition of Customary Marriages Act 120 of 1998 is a major legislative measure for the development of customary marriages in line with the constitutional principle of equality, specifically for women. The article explores the interactions between this ideal in the Act with empirical observations and the latest judicial decisions concerning its application. It considers various examples of the lack of protection of women in relationships of a customary nature, and it concludes that both the state and courts favour a formal or definitional approach to customary marriage. In considering alternative approaches that could adequately protect vulnerable parties, two conclusions emerge: First, the article recommends a wholesale revision of the South African family law approach from a focus on form to dependency. Second (and as a short-term measure), the article advocates for the putative marriage doctrine to be applied in the customary marriage context to protect many women who are denied access to 'customary marriage' as a form, and as a result, all of the benefits that flow from such marriage.
- Full Text:
- Date Issued: 2013
- Authors: Kruuse, Helen
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54094 , vital:26389 , http://journals.co.za/content/ju_jur/2013/1/EJC148455
- Description: The Recognition of Customary Marriages Act 120 of 1998 is a major legislative measure for the development of customary marriages in line with the constitutional principle of equality, specifically for women. The article explores the interactions between this ideal in the Act with empirical observations and the latest judicial decisions concerning its application. It considers various examples of the lack of protection of women in relationships of a customary nature, and it concludes that both the state and courts favour a formal or definitional approach to customary marriage. In considering alternative approaches that could adequately protect vulnerable parties, two conclusions emerge: First, the article recommends a wholesale revision of the South African family law approach from a focus on form to dependency. Second (and as a short-term measure), the article advocates for the putative marriage doctrine to be applied in the customary marriage context to protect many women who are denied access to 'customary marriage' as a form, and as a result, all of the benefits that flow from such marriage.
- Full Text:
- Date Issued: 2013
Rhodes University Research Report 2013
- Rhodes University, Roberts, Jaine, Mantolo, Thumeka, Jacob, Patricia, Macgregor, Jill, Dore, Sally
- Authors: Rhodes University , Roberts, Jaine , Mantolo, Thumeka , Jacob, Patricia , Macgregor, Jill , Dore, Sally
- Date: 2013
- Language: English
- Type: Text
- Identifier: http://hdl.handle.net/10962/59330 , vital:27549
- Description: From Foreword by Dr Saleem Badat: Rhodes University has positioned itself as a research university that, alongside excellence in undergraduate teaching, also takes scholarship seriously. This has strongly shaped the intellectual identity of the university and, today, research income and expenditure are significant components of the university’s finances. Rhodes University values the scholar-teacher model of combining research with teaching and learning, and other scholarly activities. This has a strong influence on the quality of intellectual endeavour at the University, and is critical in advancing the University’s pursuit of a strong postgraduate trajectory. This is an opportunity to briefly reflect on research at Rhodes over the eight years of my Vice-Chancellorship. It is gratifying to see that scholarship and publishing has continued to blossom at Rhodes, and has also occurred over a wider academic base, and that there has also been increased enrolments of postgraduates, as part of overall University strategy. Postgraduate enrolments increased from 24% (1 397) in 2006 to 30% (2 302) in 2013, with considerable increases in the numbers of Masters and Doctoral students. Between 2006 and 2013, Honours and Postgraduate Diploma graduations increased from 453 to 719, Masters graduations increased by 73% (from 171 to 296) and Doctoral graduations by 70% (from 46 to 78). Concomitantly, there was an increase in the numbers of black and women PhD graduates. The number of Postdoctoral Fellows at Rhodes rose from 19 in 2007 to 68 in 2013, an increase of 258%. , A publication of the Rhodes University Research Office, compiled and edited by Jaine Roberts, Thumeka Mantolo, Patricia Jacob and Jill Macgregor. Design and Layout: Sally Dore
- Full Text:
- Date Issued: 2013
- Authors: Rhodes University , Roberts, Jaine , Mantolo, Thumeka , Jacob, Patricia , Macgregor, Jill , Dore, Sally
- Date: 2013
- Language: English
- Type: Text
- Identifier: http://hdl.handle.net/10962/59330 , vital:27549
- Description: From Foreword by Dr Saleem Badat: Rhodes University has positioned itself as a research university that, alongside excellence in undergraduate teaching, also takes scholarship seriously. This has strongly shaped the intellectual identity of the university and, today, research income and expenditure are significant components of the university’s finances. Rhodes University values the scholar-teacher model of combining research with teaching and learning, and other scholarly activities. This has a strong influence on the quality of intellectual endeavour at the University, and is critical in advancing the University’s pursuit of a strong postgraduate trajectory. This is an opportunity to briefly reflect on research at Rhodes over the eight years of my Vice-Chancellorship. It is gratifying to see that scholarship and publishing has continued to blossom at Rhodes, and has also occurred over a wider academic base, and that there has also been increased enrolments of postgraduates, as part of overall University strategy. Postgraduate enrolments increased from 24% (1 397) in 2006 to 30% (2 302) in 2013, with considerable increases in the numbers of Masters and Doctoral students. Between 2006 and 2013, Honours and Postgraduate Diploma graduations increased from 453 to 719, Masters graduations increased by 73% (from 171 to 296) and Doctoral graduations by 70% (from 46 to 78). Concomitantly, there was an increase in the numbers of black and women PhD graduates. The number of Postdoctoral Fellows at Rhodes rose from 19 in 2007 to 68 in 2013, an increase of 258%. , A publication of the Rhodes University Research Office, compiled and edited by Jaine Roberts, Thumeka Mantolo, Patricia Jacob and Jill Macgregor. Design and Layout: Sally Dore
- Full Text:
- Date Issued: 2013
A marine chemical ecology study of the sea hare, Bursatella leachii in South Africa
- Authors: D'Souza, Nicole
- Date: 2013 , 2013-03-22
- Subjects: Sea hares (Mollusks) -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Ecology -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Behavior -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Defenses -- Behavior -- South Africa -- Kenton-on-Sea
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4283 , http://hdl.handle.net/10962/d1002952 , Sea hares (Mollusks) -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Ecology -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Behavior -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Defenses -- Behavior -- South Africa -- Kenton-on-Sea
- Description: The large cosmopolitan sea hare Bursatella leachii is a common resident in Eastern Cape river mouths during summer and late autumn where they congregate in beds of Zostera capensis to breed. In this thesis, the previously known toxic formamide marine secondary metabolite (-)-bursatellin (2.2), which may deter predators of South African specimens of the globally distributed sea hare Bursatella leachii, was isolated and identified (Chapter 2). There have been no previous chemical ecology studies of B. leachii and the latter half of this thesis is devoted to chemical ecology studies of this organism. Interestingly, the isolation of the (-)-diastereomer of 2.2 from specimens of B. leachii collected from the Kariega River mouth (near Kenton-on-Sea) suggests that the South African specimens of this species are similar to specimens collected from Puerto Rico and from the Mediterranean Sea. Two different chromatographic techniques for isolating 2.2 were compared in order to maximize the amount of 2.2 isolated from the Kariega River mouth sea hares. The doubling of selected resonances observed in both the ¹H and ¹³C NMR spectra of the bursatellin isolated in this study suggest one of three possibilities; either firstly, the presence of closely related compound(s), secondly, the presence of diastereomers or thirdly the presence of rotamers. Through NMR kinetic studies, we were able to establish that the presence of rotamers was very unlikely due to no change in the relative ratio (3:1) of the ¹H NMR signals with an increase in temperature. Although the attempted synthesis of the acetate derivative (2.28), as a means of separating a diastereomeric mixture was successful, the chromatographic separation of the proposed acetylated diastereomers was not successful. Preparation of the camphanate ester derivatives (e.g. 2.30) proved to be unsuccessful. Five B. leachii specimens were dissected, their organs separated and individually extracted with methanol. The methanol extracts were individually chromatographed on HP-20 media, and the distribution of bursatellin determined by isolation and NMR. It was evident from this investigation that the distribution of 2.2 within individual B. leachii specimens was found to be highest within the B. leachii ink gland. The lower amounts of 2.2 contained in the digestive system, relative to other organs, was hypothesized to occur because 2.2 is sequestered from the diet of the sea hare and efficiently moved from the gut to various organs around the body where it is stored. The absence of 2.2 from the skin was surprising and may be a result of a smaller mass of skin relative to other organs coupled with the limitations of the chromatographic separation techniques employed. Surprisingly, no bursatellin was found within juvenile sea hares. Chapter three discusses the isolation of ilimaquinone (3.1) and pelorol (3.19) from the sponge Hippospongia metachroma and the structure elucidation of each compound using computer modeling to illustrate the conformation. It was deemed necessary to isolate these well known and abundant bioactive marine natural products from a sponge as standard compounds in the bioassays given the paucity of 2.2 available for this study. Chapter four describes the assays used to test the biological activity of the bursatellin 2.2 compared to the generally bioactive ilimaquinone and the structurally related and commercially available broad spectrum antibiotic chloramphenicol. B. leachii, a shell-less marine mollusc inhabits a variety of intertidal habitats and, therefore, is exposed to several different predators, yet does not appear to have any specific predators. Potential predators of this sea hare in the Kariega Estuary could be fish and amphipods which are found in close proximity to these sea hares. Results of the assays showed that at roughly natural concentrations, (calculated from the isolated chromatographic yield) feeding was deterred by the fish and amphipods, which implied that 2.2 may confer a defensive role within the organism. The relatively high concentration present within the ink gland of B. leachii may support this hypothesis. Surprisingly, given its structural similarity to chloramphenicol, 2.3 did not show any antimicrobial action against five of the six bacterial strains against which it was screened [chloramphenicol inhibited the growth of all the bacterial strains at very low concentrations (0.25 mg/mL)]. Bursatellin was found to be only active against Staphylococus aureus at high concentrations ca. 2 mg/mL when compared to chloramphenicol. Neither bursatellin nor chloramphenicol showed anti-fungal activity. Although this study suggests that the sea hares may use chemical defences in addition to opaline ink to defend themselves, they also live within the seagrass Z. capensis, which possibly provides the sea hare with a cryptic form of physical defence against several predators that are unable to swim freely within the weed beds in the littoral zone of the estuary. , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: D'Souza, Nicole
- Date: 2013 , 2013-03-22
- Subjects: Sea hares (Mollusks) -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Ecology -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Behavior -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Defenses -- Behavior -- South Africa -- Kenton-on-Sea
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4283 , http://hdl.handle.net/10962/d1002952 , Sea hares (Mollusks) -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Ecology -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Behavior -- South Africa -- Kenton-on-Sea , Sea hares (Mollusks) -- Defenses -- Behavior -- South Africa -- Kenton-on-Sea
- Description: The large cosmopolitan sea hare Bursatella leachii is a common resident in Eastern Cape river mouths during summer and late autumn where they congregate in beds of Zostera capensis to breed. In this thesis, the previously known toxic formamide marine secondary metabolite (-)-bursatellin (2.2), which may deter predators of South African specimens of the globally distributed sea hare Bursatella leachii, was isolated and identified (Chapter 2). There have been no previous chemical ecology studies of B. leachii and the latter half of this thesis is devoted to chemical ecology studies of this organism. Interestingly, the isolation of the (-)-diastereomer of 2.2 from specimens of B. leachii collected from the Kariega River mouth (near Kenton-on-Sea) suggests that the South African specimens of this species are similar to specimens collected from Puerto Rico and from the Mediterranean Sea. Two different chromatographic techniques for isolating 2.2 were compared in order to maximize the amount of 2.2 isolated from the Kariega River mouth sea hares. The doubling of selected resonances observed in both the ¹H and ¹³C NMR spectra of the bursatellin isolated in this study suggest one of three possibilities; either firstly, the presence of closely related compound(s), secondly, the presence of diastereomers or thirdly the presence of rotamers. Through NMR kinetic studies, we were able to establish that the presence of rotamers was very unlikely due to no change in the relative ratio (3:1) of the ¹H NMR signals with an increase in temperature. Although the attempted synthesis of the acetate derivative (2.28), as a means of separating a diastereomeric mixture was successful, the chromatographic separation of the proposed acetylated diastereomers was not successful. Preparation of the camphanate ester derivatives (e.g. 2.30) proved to be unsuccessful. Five B. leachii specimens were dissected, their organs separated and individually extracted with methanol. The methanol extracts were individually chromatographed on HP-20 media, and the distribution of bursatellin determined by isolation and NMR. It was evident from this investigation that the distribution of 2.2 within individual B. leachii specimens was found to be highest within the B. leachii ink gland. The lower amounts of 2.2 contained in the digestive system, relative to other organs, was hypothesized to occur because 2.2 is sequestered from the diet of the sea hare and efficiently moved from the gut to various organs around the body where it is stored. The absence of 2.2 from the skin was surprising and may be a result of a smaller mass of skin relative to other organs coupled with the limitations of the chromatographic separation techniques employed. Surprisingly, no bursatellin was found within juvenile sea hares. Chapter three discusses the isolation of ilimaquinone (3.1) and pelorol (3.19) from the sponge Hippospongia metachroma and the structure elucidation of each compound using computer modeling to illustrate the conformation. It was deemed necessary to isolate these well known and abundant bioactive marine natural products from a sponge as standard compounds in the bioassays given the paucity of 2.2 available for this study. Chapter four describes the assays used to test the biological activity of the bursatellin 2.2 compared to the generally bioactive ilimaquinone and the structurally related and commercially available broad spectrum antibiotic chloramphenicol. B. leachii, a shell-less marine mollusc inhabits a variety of intertidal habitats and, therefore, is exposed to several different predators, yet does not appear to have any specific predators. Potential predators of this sea hare in the Kariega Estuary could be fish and amphipods which are found in close proximity to these sea hares. Results of the assays showed that at roughly natural concentrations, (calculated from the isolated chromatographic yield) feeding was deterred by the fish and amphipods, which implied that 2.2 may confer a defensive role within the organism. The relatively high concentration present within the ink gland of B. leachii may support this hypothesis. Surprisingly, given its structural similarity to chloramphenicol, 2.3 did not show any antimicrobial action against five of the six bacterial strains against which it was screened [chloramphenicol inhibited the growth of all the bacterial strains at very low concentrations (0.25 mg/mL)]. Bursatellin was found to be only active against Staphylococus aureus at high concentrations ca. 2 mg/mL when compared to chloramphenicol. Neither bursatellin nor chloramphenicol showed anti-fungal activity. Although this study suggests that the sea hares may use chemical defences in addition to opaline ink to defend themselves, they also live within the seagrass Z. capensis, which possibly provides the sea hare with a cryptic form of physical defence against several predators that are unable to swim freely within the weed beds in the littoral zone of the estuary. , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
An appraisal of the South African Government Macroeconomic Policies and Strategies (1994-2012)
- Authors: Zuma, Siziwe Monica
- Date: 2013
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:11687 , http://hdl.handle.net/10353/d1013582
- Description: This study sought to do an overview and the role of Public Administration both as an academic discipline and as a discipline in practice. It sought to do a literature analysis of the macroeconomic policies and strategies that the democratic from 1994- 2012 particularly with regards to lowering unemployment and meeting public needs. The literature review on the Freedom Charter and the South African democratic government’s macroeconomic policies namely the RDP, GEAR, ASGISA, New Growth Plan, and the National Development Plan were studied in great detail in this study. Public Finance in terms of the tax revenues collected and public debt servicing costs have contributed to the capacity of the SA government to meet its public needs and social needs including poverty eradication. It identified that the NDP because of its longer term plan approach its goals could be realizable. It identified that the South African democratic government macroeconomic policy has been consistent since 1994 that of belt tightening or fiscal policy that is tight on fiscal spending and monetary policy also has remained the same although different names have been used over the period 1994-2012. The South African democratic government since 1994 has been pursuing austere fiscal policy. This is because it inherited a government that had high public debt and therefore had to prioritise of servicing that debt. That meant that there has been less funds available to spend on public needs as the aspirations of the people when they drafted and adopted in a congress of the ANC the freedom charter in 1955. The South African democratic government through its macroeconomic policy has created a number of positive changes in the country economically and socially that have benefited a lot of the previously marginalized people of South Africa however the macroeconomic objectives of reducing unemployment, growing the economy, increasing exports and lowering inflation still remain a huge challenge in this country. This study concludes that in order to increase revenues to meet public needs government needs to look at increasing its revenue base rather than borrowing the money as that will create the same challenge that it is currently facing hence it adopted the austere fiscal policy.
- Full Text:
- Date Issued: 2013
- Authors: Zuma, Siziwe Monica
- Date: 2013
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:11687 , http://hdl.handle.net/10353/d1013582
- Description: This study sought to do an overview and the role of Public Administration both as an academic discipline and as a discipline in practice. It sought to do a literature analysis of the macroeconomic policies and strategies that the democratic from 1994- 2012 particularly with regards to lowering unemployment and meeting public needs. The literature review on the Freedom Charter and the South African democratic government’s macroeconomic policies namely the RDP, GEAR, ASGISA, New Growth Plan, and the National Development Plan were studied in great detail in this study. Public Finance in terms of the tax revenues collected and public debt servicing costs have contributed to the capacity of the SA government to meet its public needs and social needs including poverty eradication. It identified that the NDP because of its longer term plan approach its goals could be realizable. It identified that the South African democratic government macroeconomic policy has been consistent since 1994 that of belt tightening or fiscal policy that is tight on fiscal spending and monetary policy also has remained the same although different names have been used over the period 1994-2012. The South African democratic government since 1994 has been pursuing austere fiscal policy. This is because it inherited a government that had high public debt and therefore had to prioritise of servicing that debt. That meant that there has been less funds available to spend on public needs as the aspirations of the people when they drafted and adopted in a congress of the ANC the freedom charter in 1955. The South African democratic government through its macroeconomic policy has created a number of positive changes in the country economically and socially that have benefited a lot of the previously marginalized people of South Africa however the macroeconomic objectives of reducing unemployment, growing the economy, increasing exports and lowering inflation still remain a huge challenge in this country. This study concludes that in order to increase revenues to meet public needs government needs to look at increasing its revenue base rather than borrowing the money as that will create the same challenge that it is currently facing hence it adopted the austere fiscal policy.
- Full Text:
- Date Issued: 2013
An appraisal of the South African government macroeconomic policies and strategies (1994-2012)
- Authors: Zuma, Siziwe Monica
- Date: 2013
- Subjects: Fiscal policy--South Africa Macroeconomics Monetary policy--South Africa
- Language: English
- Type: Thesis , Masters , Public Administration
- Identifier: http://hdl.handle.net/10353/17360 , vital:40959
- Description: This study sought to do an overview and the role of Public Administration both as an academic discipline and as a discipline in practice. It sought to do a literature analysis of the macroeconomic policies and strategies that the democratic from 1994- 2012 particularly with regards to lowering unemployment and meeting public needs. The literature review on the Freedom Charter and the South African democratic government’s macroeconomic policies namely the RDP, GEAR, ASGISA, New Growth Plan, and the National Development Plan were studied in great detail in this study. Public Finance in terms of the tax revenues collected and public debt servicing costs have contributed to the capacity of the SA government to meet its public needs and social needs including poverty eradication. It identified that the NDP because of its longer term plan approach its goals could be realizable. It identified that the South African democratic government macroeconomic policy has been consistent since 1994 that of belt tightening or fiscal policy that is tight on fiscal spending and monetary policy also has remained the same although different names have been used over the period 1994-2012. The South African democratic government since 1994 has been pursuing austere fiscal policy. This is because it inherited a government that had high public debt and therefore had to prioritise of servicing that debt. That meant that there has been less funds available to spend on public needs as the aspirations of the people when they drafted and adopted in a congress of the ANC the freedom charter in 1955. The South African democratic government through its macroeconomic policy has created a number of positive changes in the country economically and socially that have benefited a lot of the previously marginalized people of South Africa however the macroeconomic objectives of reducing unemployment, growing the economy, increasing exports and lowering inflation still remain a huge challenge in this country. This study concludes that in order to increase revenues to meet public needs government needs to look at increasing its revenue base rather than borrowing the money as that will create the same challenge that it is currently facing hence it adopted the austere fiscal policy.
- Full Text:
- Date Issued: 2013
- Authors: Zuma, Siziwe Monica
- Date: 2013
- Subjects: Fiscal policy--South Africa Macroeconomics Monetary policy--South Africa
- Language: English
- Type: Thesis , Masters , Public Administration
- Identifier: http://hdl.handle.net/10353/17360 , vital:40959
- Description: This study sought to do an overview and the role of Public Administration both as an academic discipline and as a discipline in practice. It sought to do a literature analysis of the macroeconomic policies and strategies that the democratic from 1994- 2012 particularly with regards to lowering unemployment and meeting public needs. The literature review on the Freedom Charter and the South African democratic government’s macroeconomic policies namely the RDP, GEAR, ASGISA, New Growth Plan, and the National Development Plan were studied in great detail in this study. Public Finance in terms of the tax revenues collected and public debt servicing costs have contributed to the capacity of the SA government to meet its public needs and social needs including poverty eradication. It identified that the NDP because of its longer term plan approach its goals could be realizable. It identified that the South African democratic government macroeconomic policy has been consistent since 1994 that of belt tightening or fiscal policy that is tight on fiscal spending and monetary policy also has remained the same although different names have been used over the period 1994-2012. The South African democratic government since 1994 has been pursuing austere fiscal policy. This is because it inherited a government that had high public debt and therefore had to prioritise of servicing that debt. That meant that there has been less funds available to spend on public needs as the aspirations of the people when they drafted and adopted in a congress of the ANC the freedom charter in 1955. The South African democratic government through its macroeconomic policy has created a number of positive changes in the country economically and socially that have benefited a lot of the previously marginalized people of South Africa however the macroeconomic objectives of reducing unemployment, growing the economy, increasing exports and lowering inflation still remain a huge challenge in this country. This study concludes that in order to increase revenues to meet public needs government needs to look at increasing its revenue base rather than borrowing the money as that will create the same challenge that it is currently facing hence it adopted the austere fiscal policy.
- Full Text:
- Date Issued: 2013
Falcipains as malarial drug targets
- Authors: Kanzi, Aquillah Mumo
- Date: 2013
- Subjects: Malaria Malaria -- Chemotherapy Plasmodium falciparum Antimalarials -- Development Cysteine proteinases Cysteine proteinases -- Inhibitors Papain Drug development Bioinformatics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3897 , http://hdl.handle.net/10962/d1003842
- Description: Malaria is an infectious disease caused by parasites of the Plasmodium genus with mortality rates of more than a million annually, hence a major global public health concern. Plasmodium falciparum (P. falciparum) accounts for over 90% of malaria incidence. Increased resistance to antimalarial drugs by the Plasmodium parasite, coupled with the lack of an effective malaria vaccine necessitates the urgent need for new research avenues to develop novel and more potent antimalarial drugs. This study focused on falcipains, a group of P. falciparum cysteine proteases that belong to the clan CA and papain family C1, that have emerged as potential drug targets due to their involvement in a range of crucial functions in the P. falciparum life cycle. Recently, falcipain-2 has been validated as a drug target but little is known of its Plasmodium orthologs. Currently, there are several falcipain inhibitors that have been identified, most of which are peptide based but none has proceeded to drug development due to associated poor pharmacological profiles and susceptibility to degradation by host cysteine proteases. Non-peptides inhibitors have been shown to be more stable in vivo but limited information exists. In vivo studies on falcipain-2 and falcipain-3 inhibitors have also been complicated by varying outcomes, thus a good understanding of the structural variations of falcipain Plasmodium orthologs at the active site could go a long way to ease in vivo results interpretation and effective inhibitor design. In this study, we use bioinformatics approaches to perform comparative sequence and structural analysis and molecular docking to characterize protein-inhibitor interactions of falcipain homologs at the active site. Known FP-2 and FP-3 small molecule nonpeptide inhibitors were used to identify residue variations and their effect on inhibitor binding. This was done with the aim of screening a collection of selected non-peptide compounds of South African natural origin to identify possible new inhibitor leads. Natural compounds with high binding affinities across all Plasmodium orthologs were identified. These compounds were then used to search the ZINC database for similar compounds which could have better binding affinities across all selected falcipain homologs. Compounds with high binding affinities across all Plasmodium orthologs were found.
- Full Text:
- Date Issued: 2013
- Authors: Kanzi, Aquillah Mumo
- Date: 2013
- Subjects: Malaria Malaria -- Chemotherapy Plasmodium falciparum Antimalarials -- Development Cysteine proteinases Cysteine proteinases -- Inhibitors Papain Drug development Bioinformatics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3897 , http://hdl.handle.net/10962/d1003842
- Description: Malaria is an infectious disease caused by parasites of the Plasmodium genus with mortality rates of more than a million annually, hence a major global public health concern. Plasmodium falciparum (P. falciparum) accounts for over 90% of malaria incidence. Increased resistance to antimalarial drugs by the Plasmodium parasite, coupled with the lack of an effective malaria vaccine necessitates the urgent need for new research avenues to develop novel and more potent antimalarial drugs. This study focused on falcipains, a group of P. falciparum cysteine proteases that belong to the clan CA and papain family C1, that have emerged as potential drug targets due to their involvement in a range of crucial functions in the P. falciparum life cycle. Recently, falcipain-2 has been validated as a drug target but little is known of its Plasmodium orthologs. Currently, there are several falcipain inhibitors that have been identified, most of which are peptide based but none has proceeded to drug development due to associated poor pharmacological profiles and susceptibility to degradation by host cysteine proteases. Non-peptides inhibitors have been shown to be more stable in vivo but limited information exists. In vivo studies on falcipain-2 and falcipain-3 inhibitors have also been complicated by varying outcomes, thus a good understanding of the structural variations of falcipain Plasmodium orthologs at the active site could go a long way to ease in vivo results interpretation and effective inhibitor design. In this study, we use bioinformatics approaches to perform comparative sequence and structural analysis and molecular docking to characterize protein-inhibitor interactions of falcipain homologs at the active site. Known FP-2 and FP-3 small molecule nonpeptide inhibitors were used to identify residue variations and their effect on inhibitor binding. This was done with the aim of screening a collection of selected non-peptide compounds of South African natural origin to identify possible new inhibitor leads. Natural compounds with high binding affinities across all Plasmodium orthologs were identified. These compounds were then used to search the ZINC database for similar compounds which could have better binding affinities across all selected falcipain homologs. Compounds with high binding affinities across all Plasmodium orthologs were found.
- Full Text:
- Date Issued: 2013
Application of lie group analysis to mathematical models in epidemiology
- Authors: Otieno, Andrew Alex Omondi
- Date: 2013
- Subjects: Epidemiology -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18486 , http://hdl.handle.net/11260/100
- Description: Lie group analysis is arguably the most systematic vehicle for finding exact solutions of differential equations. Using this approach one has at one's disposal a variety of algorithms that make the solution process of many differential equations algorithmic. Vital properties of a given differential equation can often be inferred from the symmetries admitted by the equation. However, Lie group analysis has not enjoyed wide-spread application to systems of first-order ordinary differential equations. This is because such systems typically admit an infinite number of Lie point symmetries, and there is no systematic way to find even a single nontrivial one-dimensional Lie symmetry algebra. In the few applications available, the approach has been to circumvent the problem by transforming a given system of first-order ordinary differential equations into one in which at least one of the equations is of order two or greater. It is therefore fair to say that the full power of Lie group analysis has not been sufficiently harnessed in the solution of systems of first-order ordinary differential equations. In this dissertation we review some applications of Lie group analysis to systems of first order ordinary differential equations. We shed light on the integration procedure for first-order systems of ordinary differential equations admitting a solvable Lie algebra. We do this via instructive examples drawn from mathematical epidemiology models. In particular we revisit the work of Nucci and Torrisi [54] and improve the exposition of the Lie-symmetry-inspired solution of a mathematical model which describes a HIV transmission. To aid implementation of the integration strategy for systems of ordinary differential equations, we have developed ad-hoc routines for finding particular types of admitted symmetries and checking if a given symmetry is indeed admitted by a system of ordinary differential equations.
- Full Text:
- Date Issued: 2013
- Authors: Otieno, Andrew Alex Omondi
- Date: 2013
- Subjects: Epidemiology -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18486 , http://hdl.handle.net/11260/100
- Description: Lie group analysis is arguably the most systematic vehicle for finding exact solutions of differential equations. Using this approach one has at one's disposal a variety of algorithms that make the solution process of many differential equations algorithmic. Vital properties of a given differential equation can often be inferred from the symmetries admitted by the equation. However, Lie group analysis has not enjoyed wide-spread application to systems of first-order ordinary differential equations. This is because such systems typically admit an infinite number of Lie point symmetries, and there is no systematic way to find even a single nontrivial one-dimensional Lie symmetry algebra. In the few applications available, the approach has been to circumvent the problem by transforming a given system of first-order ordinary differential equations into one in which at least one of the equations is of order two or greater. It is therefore fair to say that the full power of Lie group analysis has not been sufficiently harnessed in the solution of systems of first-order ordinary differential equations. In this dissertation we review some applications of Lie group analysis to systems of first order ordinary differential equations. We shed light on the integration procedure for first-order systems of ordinary differential equations admitting a solvable Lie algebra. We do this via instructive examples drawn from mathematical epidemiology models. In particular we revisit the work of Nucci and Torrisi [54] and improve the exposition of the Lie-symmetry-inspired solution of a mathematical model which describes a HIV transmission. To aid implementation of the integration strategy for systems of ordinary differential equations, we have developed ad-hoc routines for finding particular types of admitted symmetries and checking if a given symmetry is indeed admitted by a system of ordinary differential equations.
- Full Text:
- Date Issued: 2013
Effects of crop rotation and tillage system on the control of ryegrass (lolium multiflorum X perenne) in wheat (triticum aestivum) in the Swartland production area of South Africa's Western Cape Province
- Authors: Nteyi, Sinovuyo Mava
- Date: 2013
- Subjects: Cropping systems , Conservation tillage -- South Africa -- Western Cape , Ryegrasses
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10738 , http://hdl.handle.net/10948/d1020990
- Description: A major challenge facing agriculture today is to sustain the productivity of agricultural systems with the reduction of weed invasion. The Swartland region in the Western Cape (South Africa) is intensively cropped, producing wheat (Triticum aestivum) as the major crop. As a result of the weedy ryegrass invasion the wheat yield is reduced. In addition, ryegrass has developed resistance to grass herbicides (graminicides). This situation has increased the need to use alternative practices for controlling the invasion of ryegrass in wheat fields. In this regard, crop rotation and tillage systems were proposed as techniques to suppress the ryegrass invasion. This could thus maintain a sustainable long-term wheat production system with less application of herbicides, decreased input costs and increased total grain yield. Against this background, the effects of crop rotation and tillage were determined on ryegrass seedling emergence in a field and shade netting experiment, while seed dormancy was determined in the laboratory. The objectives were to compare the wheat production of two crop rotations with mono-cropped wheat and assess the impact on the ryegrass population in no-till and minimum tillage systems. Analyses of variance on data sets of ryegrass seeds from 2009, 2010 and 2011 were used to determine germination and dormancy percentages in laboratory experiments. The performance of laboratory treatments was evaluated on the basis of germination percentage of seeds. In the field and shade netting experiments, analyses of variance for data from 2007, 2011 and 2012 were used to determine crop rotation x tillage system response. Field and shade netting performance were evaluated on the basis of ryegrass population inhibition and stimulation respectively. Ryegrass seeds from 2009 and 2010 showed higher germination percentages (80 per cent and 73 per cent) than 2011 (42 per cent). Primary dormancy prevented high germination of newly harvested seeds as dormancy release increase with age of the seed. Results of field and shade netting experiments showed stimulation of the ryegrass weed population in wheat monoculture under minimum tillage. However, when wheat was rotated with leguminous crops under both tillage systems (minimum-till and no-till) ryegrass was significantly inhibited. It was concluded that the critical period for weed competition is the first six weeks after planting. Results from this study provide a basis for producers of cereals to make good decisions with regards to timing weed control measures. It is essential to use competitive crop sequences which will inhibit weeds. The challenge is getting this practice adopted and implemented by producers as it will promote conservation agriculture within the region. This study promotes long-term sustainable wheat production systems with an efficient weed management programme that is environmentally friendly using less herbicides within the Swartland region.
- Full Text:
- Date Issued: 2013
- Authors: Nteyi, Sinovuyo Mava
- Date: 2013
- Subjects: Cropping systems , Conservation tillage -- South Africa -- Western Cape , Ryegrasses
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10738 , http://hdl.handle.net/10948/d1020990
- Description: A major challenge facing agriculture today is to sustain the productivity of agricultural systems with the reduction of weed invasion. The Swartland region in the Western Cape (South Africa) is intensively cropped, producing wheat (Triticum aestivum) as the major crop. As a result of the weedy ryegrass invasion the wheat yield is reduced. In addition, ryegrass has developed resistance to grass herbicides (graminicides). This situation has increased the need to use alternative practices for controlling the invasion of ryegrass in wheat fields. In this regard, crop rotation and tillage systems were proposed as techniques to suppress the ryegrass invasion. This could thus maintain a sustainable long-term wheat production system with less application of herbicides, decreased input costs and increased total grain yield. Against this background, the effects of crop rotation and tillage were determined on ryegrass seedling emergence in a field and shade netting experiment, while seed dormancy was determined in the laboratory. The objectives were to compare the wheat production of two crop rotations with mono-cropped wheat and assess the impact on the ryegrass population in no-till and minimum tillage systems. Analyses of variance on data sets of ryegrass seeds from 2009, 2010 and 2011 were used to determine germination and dormancy percentages in laboratory experiments. The performance of laboratory treatments was evaluated on the basis of germination percentage of seeds. In the field and shade netting experiments, analyses of variance for data from 2007, 2011 and 2012 were used to determine crop rotation x tillage system response. Field and shade netting performance were evaluated on the basis of ryegrass population inhibition and stimulation respectively. Ryegrass seeds from 2009 and 2010 showed higher germination percentages (80 per cent and 73 per cent) than 2011 (42 per cent). Primary dormancy prevented high germination of newly harvested seeds as dormancy release increase with age of the seed. Results of field and shade netting experiments showed stimulation of the ryegrass weed population in wheat monoculture under minimum tillage. However, when wheat was rotated with leguminous crops under both tillage systems (minimum-till and no-till) ryegrass was significantly inhibited. It was concluded that the critical period for weed competition is the first six weeks after planting. Results from this study provide a basis for producers of cereals to make good decisions with regards to timing weed control measures. It is essential to use competitive crop sequences which will inhibit weeds. The challenge is getting this practice adopted and implemented by producers as it will promote conservation agriculture within the region. This study promotes long-term sustainable wheat production systems with an efficient weed management programme that is environmentally friendly using less herbicides within the Swartland region.
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- Date Issued: 2013