Practice guidelines for culturally sensitive drug prevention interventions
- Authors: Goliath, Veonna
- Date: 2014
- Subjects: Youth -- Drug use -- South Africa -- Port Elizabeth , Drug abuse -- South Africa -- Port Elizabeth -- Prevention , Ethnicity -- South Africa -- Port Elizabeth , Drug abuse -- Treatment -- South Africa -- Port Elizabeth , Drug abuse -- Social aspects -- South Africa -- Port Elizabeth , Group identity -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10005 , http://hdl.handle.net/10948/d1017193
- Description: South Africa has experienced a notable increase in adolescent drug use during the country’s transition from apartheid to democracy (Central Drug Authority [CDA], 2006). These findings are verified by epidemiological studies and two national youth risk behaviour surveys, highlighting the need for effective drug prevention interventions. Whilst drug use spans across age, gender and social strata, the rapid increase in both legal and illicit drug use among adolescents in the Northern Areas communities of Port Elizabeth has been particularly pronounced. The South African Community Epidemiology Network on Drug Use (SACENDU) statistics, which reflects on racial demographics in accordance with the Population Registration Act of 1950 (South Africa, 1950), reports that, in the year 2011, the ‘Coloured’ population constituted 62 percent of those individuals seeking treatment for drug abuse, compared to 15 percent ‘African’ treatment seekers in Port Elizabeth (Dada, Plüddemann, Parry, Bhana, Vawda & Fourie, 2012:44). Furthermore, methamphetamine use by persons under the age of 20 years in Port Elizabeth increased fivefold in a three-year period, i.e. from 7 percent in 2008 to 39 percent in 2011 (Dada et al., 2012), with the ‘Coloured’ population group accounting for the majority of methamphetamine users. These statistics reinforce a long-standing racial stereotype that associates ‘Coloured’ racial identity with an enhanced susceptibility to drug use. The National Drug Master Plan (South Africa, 2012a), and the Prevention of and Treatment for Substance Abuse Act (Act no 70 of 2008) propose that drug prevention programmes should address the values, perceptions, expectations and beliefs that the community associates with drug abuse (South Africa, 2008b). This view emphasises the importance of drug preventions interventions that are culturally sensitive and contextually relevant. The current study was guided by two conceptual frameworks, i.e. the Social Constructionist Framework and the Ecological Risk/Protective Resilience Framework, and focused on the Northern Areas of Port Elizabeth, a historically marginalised community inhabited by a predominantly ‘Coloured’ indigenous/ethnic group. The goal of the study was to enhance understanding of the socio-cultural meaning attributed to cultural identity, drug use, non-use and drug prevention in the Northern Areas of Port Elizabeth, with the view to developing guidelines for drug prevention interventions that are culturally sensitive and contextually relevant. The following objectives were formulated in order to achieve the goal of the study: • To explore adolescent narratives regarding the constructs ‘Coloured’, drug use, non-use and drug prevention programmes of three distinct groups of adolescents (drug users, non-users, and TADA peer mentors) from the Northern Areas. • To explore and describe the social service practitioners’ (social workers and social auxiliary workers’) constructions of drug use, non-use and drug abuse prevention in relation to adolescents from the Northern Areas, and how such constructions inform the drug prevention services rendered to adolescents from these communities. • To review the data collected from the adolescent narratives and the social service practitioners’ reflections on their drug prevention programmes against existing theory and models for drug prevention. • To synthesise the above information with a view to developing guidelines for culturally sensitive drug prevention programmes relevant and responsive to the specific social constructions of adolescents from the Northern Areas. A qualitative research approach, located in a narrative tradition of inquiry research design, was employed to achieve the goal of the study (Riessman, 2008). The study was conducted in two phases. The first phase involved an empirical study with the four sample groups (i.e. adolescent drug users, adolescent non-drug users, Teenagers against Drug Abuse [TADA] peer mentors and social service professionals (i.e. social workers and social auxiliary workers)). Phase two involved the co-construction of the practice guidelines for culturally sensitive and contextually relevant drug prevention interventions. Phase one started with the informal exploration of community stakeholders’ views on the identified research problem and the process of gaining access to the research population. Several gatekeepers (i.e. teachers, social workers, the Families Against Drugs [FAD] Support Group representatives, a minister of religion and a community stakeholder) were engaged to assist in recruiting participants from the four sample groups. A non-probability purposive sampling method was employed to purposively recruit 29 adolescent non-drug users and ten adolescent peer mentors (via the TADA Programme at one school). The same sampling method, followed by a snowball sampling technique, was employed to recruit the two remaining sample groups of ten adolescent drug users (in the recovery process) and nine social workers and social auxiliary workers respectively. The sample sizes were determined by the principle of data saturation.The data generation method used in respect of the non-users took the form of semi-structured written narratives, administered in a group context during school time, followed by a second round of data generation. The life-grid (Wilson, Cunningham-Burley, Bancroft, Backett-Milburn & Masters, 2007:144), a qualitative visual tool for mapping important life events, was employed to guide the co-construction of the biographical narratives generated during the individual semi-structured interviews with the sample of adolescent drug users. Focus group interviews were used to enhance an understanding of the peer mentors and social service practitioners’ views on the construct ‘Coloured’ and their existing drug prevention programmes. Each of the individual and focus group interviews was audio-recorded, transcribed and complemented by the field notes. Informal data gathering occurred through participant observation of two drug prevention programmes, attendance of a FAD Support Group meeting, and interviews with community volunteers and the South African Police Services (SAPS) Youth Development Forum. Both the content and the context of the narratives were analysed to arrive at the research themes, sub-themes and categories. The content of the narratives was analysed by employing categorical content analysis, whilst the form of the narratives (i.e. how the stories were told) was analysed by using the socio-cultural approach to narrative analysis (Grbich, 2007:130). The journey metaphor emerged from the adolescent drug users’ narratives, depicting a prototypical storyline of a drug use journey, starting with experimentation and culminating in abuse and dependence for some and an early exit from the journey for others. The conclusions that can be drawn from these findings illuminate key protective factors and processes at a multisystemic level that can be strengthened to enhance the adolescents’ resistance to drug use and/or delay the onset of use. Embedded in the participants’ narration of the drug use journey were nuances relating to internalised stereotypes of ‘White’ supremacy and ‘Coloured’ inferiority as an explanatory framework for venturing onto and prolonging the journey.The two themes that emerged during the process of content and narrative analysis of the qualitative data (from both adolescent drug users and non-users) were as follows: Constructing drug use as a ‘Coloured’ phenomenon and reconstructing ‘Coloured’ identity; Risk and protective factors located at individual, family, peer, school, community and societal domains. The four themes that emerged during the data analysis of the peer mentors and social service practitioners’ narratives were as follows: Construction of ‘Coloured’ identity; socio-cultural meaning construction about the reasons for drug use amongst adolescents from the Northern Areas; description of drug prevention services rendered in the Northern Areas; and reflection on barriers to rendering drug prevention interventions.
- Full Text:
- Date Issued: 2014
- Authors: Goliath, Veonna
- Date: 2014
- Subjects: Youth -- Drug use -- South Africa -- Port Elizabeth , Drug abuse -- South Africa -- Port Elizabeth -- Prevention , Ethnicity -- South Africa -- Port Elizabeth , Drug abuse -- Treatment -- South Africa -- Port Elizabeth , Drug abuse -- Social aspects -- South Africa -- Port Elizabeth , Group identity -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10005 , http://hdl.handle.net/10948/d1017193
- Description: South Africa has experienced a notable increase in adolescent drug use during the country’s transition from apartheid to democracy (Central Drug Authority [CDA], 2006). These findings are verified by epidemiological studies and two national youth risk behaviour surveys, highlighting the need for effective drug prevention interventions. Whilst drug use spans across age, gender and social strata, the rapid increase in both legal and illicit drug use among adolescents in the Northern Areas communities of Port Elizabeth has been particularly pronounced. The South African Community Epidemiology Network on Drug Use (SACENDU) statistics, which reflects on racial demographics in accordance with the Population Registration Act of 1950 (South Africa, 1950), reports that, in the year 2011, the ‘Coloured’ population constituted 62 percent of those individuals seeking treatment for drug abuse, compared to 15 percent ‘African’ treatment seekers in Port Elizabeth (Dada, Plüddemann, Parry, Bhana, Vawda & Fourie, 2012:44). Furthermore, methamphetamine use by persons under the age of 20 years in Port Elizabeth increased fivefold in a three-year period, i.e. from 7 percent in 2008 to 39 percent in 2011 (Dada et al., 2012), with the ‘Coloured’ population group accounting for the majority of methamphetamine users. These statistics reinforce a long-standing racial stereotype that associates ‘Coloured’ racial identity with an enhanced susceptibility to drug use. The National Drug Master Plan (South Africa, 2012a), and the Prevention of and Treatment for Substance Abuse Act (Act no 70 of 2008) propose that drug prevention programmes should address the values, perceptions, expectations and beliefs that the community associates with drug abuse (South Africa, 2008b). This view emphasises the importance of drug preventions interventions that are culturally sensitive and contextually relevant. The current study was guided by two conceptual frameworks, i.e. the Social Constructionist Framework and the Ecological Risk/Protective Resilience Framework, and focused on the Northern Areas of Port Elizabeth, a historically marginalised community inhabited by a predominantly ‘Coloured’ indigenous/ethnic group. The goal of the study was to enhance understanding of the socio-cultural meaning attributed to cultural identity, drug use, non-use and drug prevention in the Northern Areas of Port Elizabeth, with the view to developing guidelines for drug prevention interventions that are culturally sensitive and contextually relevant. The following objectives were formulated in order to achieve the goal of the study: • To explore adolescent narratives regarding the constructs ‘Coloured’, drug use, non-use and drug prevention programmes of three distinct groups of adolescents (drug users, non-users, and TADA peer mentors) from the Northern Areas. • To explore and describe the social service practitioners’ (social workers and social auxiliary workers’) constructions of drug use, non-use and drug abuse prevention in relation to adolescents from the Northern Areas, and how such constructions inform the drug prevention services rendered to adolescents from these communities. • To review the data collected from the adolescent narratives and the social service practitioners’ reflections on their drug prevention programmes against existing theory and models for drug prevention. • To synthesise the above information with a view to developing guidelines for culturally sensitive drug prevention programmes relevant and responsive to the specific social constructions of adolescents from the Northern Areas. A qualitative research approach, located in a narrative tradition of inquiry research design, was employed to achieve the goal of the study (Riessman, 2008). The study was conducted in two phases. The first phase involved an empirical study with the four sample groups (i.e. adolescent drug users, adolescent non-drug users, Teenagers against Drug Abuse [TADA] peer mentors and social service professionals (i.e. social workers and social auxiliary workers)). Phase two involved the co-construction of the practice guidelines for culturally sensitive and contextually relevant drug prevention interventions. Phase one started with the informal exploration of community stakeholders’ views on the identified research problem and the process of gaining access to the research population. Several gatekeepers (i.e. teachers, social workers, the Families Against Drugs [FAD] Support Group representatives, a minister of religion and a community stakeholder) were engaged to assist in recruiting participants from the four sample groups. A non-probability purposive sampling method was employed to purposively recruit 29 adolescent non-drug users and ten adolescent peer mentors (via the TADA Programme at one school). The same sampling method, followed by a snowball sampling technique, was employed to recruit the two remaining sample groups of ten adolescent drug users (in the recovery process) and nine social workers and social auxiliary workers respectively. The sample sizes were determined by the principle of data saturation.The data generation method used in respect of the non-users took the form of semi-structured written narratives, administered in a group context during school time, followed by a second round of data generation. The life-grid (Wilson, Cunningham-Burley, Bancroft, Backett-Milburn & Masters, 2007:144), a qualitative visual tool for mapping important life events, was employed to guide the co-construction of the biographical narratives generated during the individual semi-structured interviews with the sample of adolescent drug users. Focus group interviews were used to enhance an understanding of the peer mentors and social service practitioners’ views on the construct ‘Coloured’ and their existing drug prevention programmes. Each of the individual and focus group interviews was audio-recorded, transcribed and complemented by the field notes. Informal data gathering occurred through participant observation of two drug prevention programmes, attendance of a FAD Support Group meeting, and interviews with community volunteers and the South African Police Services (SAPS) Youth Development Forum. Both the content and the context of the narratives were analysed to arrive at the research themes, sub-themes and categories. The content of the narratives was analysed by employing categorical content analysis, whilst the form of the narratives (i.e. how the stories were told) was analysed by using the socio-cultural approach to narrative analysis (Grbich, 2007:130). The journey metaphor emerged from the adolescent drug users’ narratives, depicting a prototypical storyline of a drug use journey, starting with experimentation and culminating in abuse and dependence for some and an early exit from the journey for others. The conclusions that can be drawn from these findings illuminate key protective factors and processes at a multisystemic level that can be strengthened to enhance the adolescents’ resistance to drug use and/or delay the onset of use. Embedded in the participants’ narration of the drug use journey were nuances relating to internalised stereotypes of ‘White’ supremacy and ‘Coloured’ inferiority as an explanatory framework for venturing onto and prolonging the journey.The two themes that emerged during the process of content and narrative analysis of the qualitative data (from both adolescent drug users and non-users) were as follows: Constructing drug use as a ‘Coloured’ phenomenon and reconstructing ‘Coloured’ identity; Risk and protective factors located at individual, family, peer, school, community and societal domains. The four themes that emerged during the data analysis of the peer mentors and social service practitioners’ narratives were as follows: Construction of ‘Coloured’ identity; socio-cultural meaning construction about the reasons for drug use amongst adolescents from the Northern Areas; description of drug prevention services rendered in the Northern Areas; and reflection on barriers to rendering drug prevention interventions.
- Full Text:
- Date Issued: 2014
Purification and characterization of TbHsp70.c, a novel Hsp70 from Trypanosoma brucei
- Authors: Burger, Adélle
- Date: 2014
- Subjects: African trypanosomiasis -- Research Heat shock proteins -- Research Trypanosoma brucei -- Research Mycobacterial diseases -- Research -- Africa Parasitic diseases -- Africa -- Prevention Parasites -- Physiology Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4105 , http://hdl.handle.net/10962/d1011618
- Description: One of Africa’s neglected tropical diseases, African Trypanosomiasis, is not only fatal but also has a crippling impact on economic development. Heat shock proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. The expression of heat shock proteins increases during these heat shock conditions, and this is considered to play a role in differentiation of these vector-borne parasites. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is involved in protein homeostasis, Hsp40 acts as a co-chaperone and stimulates its intrinsically weak ATPase activity. In silico analysis of the T. brucei genome has revealed the existence of 12 Hsp70 proteins and 65 Hsp40 proteins to date. A novel Hsp70, TbHsp70.c, was recently identified in T. brucei. Different from the prototypical Hsp70, TbHsp70.c contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. By implication the substrate range and mechanism by which the substrates are recognized may be novel. The ability of a Type I Hsp40, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective of this study was to biochemically characterize TbHsp70.c and its partnership with Tbj2 to further enhance our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed chaperone activities in their ability to suppress aggregation of thermolabile MDH. TbHsp70.c also suppressed aggregation of rhodanese. ATPase assays revealed that the ATPase activity of TbHsp70.c was stimulated by Tbj2. The targeted inhibition of the function of heat shock proteins is emerging as a tool to combat disease. The small molecule modulators quercetin and methylene blue are known to inhibit the ATPase activity of Hsp70. However, methylene blue did not significantly inhibit the ATPase activity of TbHsp70.c; while quercetin, did inhibit the ATPase activity. In vivo heat stress experiments indicated an up-regulation of the expression levels of TbHsp70.c. RNA interference studies showed partial knockdown of TbHsp70.c with no detrimental effect on the parasite. Fluorescence microscopy studies of TbHsp70.c showed a probable cytoplasmic subcellular localization. In this study both TbHsp70.c and Tbj2 demonstrated chaperone activity and Tbj2 possibly functions as a co-chaperone of TbHsp70.c.
- Full Text:
- Date Issued: 2014
- Authors: Burger, Adélle
- Date: 2014
- Subjects: African trypanosomiasis -- Research Heat shock proteins -- Research Trypanosoma brucei -- Research Mycobacterial diseases -- Research -- Africa Parasitic diseases -- Africa -- Prevention Parasites -- Physiology Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4105 , http://hdl.handle.net/10962/d1011618
- Description: One of Africa’s neglected tropical diseases, African Trypanosomiasis, is not only fatal but also has a crippling impact on economic development. Heat shock proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. The expression of heat shock proteins increases during these heat shock conditions, and this is considered to play a role in differentiation of these vector-borne parasites. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is involved in protein homeostasis, Hsp40 acts as a co-chaperone and stimulates its intrinsically weak ATPase activity. In silico analysis of the T. brucei genome has revealed the existence of 12 Hsp70 proteins and 65 Hsp40 proteins to date. A novel Hsp70, TbHsp70.c, was recently identified in T. brucei. Different from the prototypical Hsp70, TbHsp70.c contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. By implication the substrate range and mechanism by which the substrates are recognized may be novel. The ability of a Type I Hsp40, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective of this study was to biochemically characterize TbHsp70.c and its partnership with Tbj2 to further enhance our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed chaperone activities in their ability to suppress aggregation of thermolabile MDH. TbHsp70.c also suppressed aggregation of rhodanese. ATPase assays revealed that the ATPase activity of TbHsp70.c was stimulated by Tbj2. The targeted inhibition of the function of heat shock proteins is emerging as a tool to combat disease. The small molecule modulators quercetin and methylene blue are known to inhibit the ATPase activity of Hsp70. However, methylene blue did not significantly inhibit the ATPase activity of TbHsp70.c; while quercetin, did inhibit the ATPase activity. In vivo heat stress experiments indicated an up-regulation of the expression levels of TbHsp70.c. RNA interference studies showed partial knockdown of TbHsp70.c with no detrimental effect on the parasite. Fluorescence microscopy studies of TbHsp70.c showed a probable cytoplasmic subcellular localization. In this study both TbHsp70.c and Tbj2 demonstrated chaperone activity and Tbj2 possibly functions as a co-chaperone of TbHsp70.c.
- Full Text:
- Date Issued: 2014
Separation of rhodium (III) and iridium (IV) using functional polymeric materials
- Authors: Majavu, Avela
- Date: 2014
- Subjects: Rhodium -- Separation , Iridium -- Separation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6576 , vital:21116
- Description: Poly(vinylbenzylchloride) (PVBC) nanofibers were fabricated by the electrospinning process. The Merrifield micropheres, silica microsparticles and PVBC nanofibers were functionalised with different quaternary diammonium groups derived from ethylenediamine (EDA), tetramethylenediamine (TMDA), hexamethylenediamine (HMDA), 1,8-diaminooctane (OMDA), 1,10-diaminodecane (DMDA) and 1,12-diaminododecane (DDMDA) and investigated for separation of [RhCl5(H2O)]2- and [IrCl6]2-. The sorbent materials were characterised by means of FTIR, XPS, SEM, BET surface area, thermogravimetric analysis and elemental analysis, and characterization results showed that the functionalization of the sorbent materials was successful. Batch equilibrium studies were carried out to assess the efficiency of these different anion exchangers using single metal aqueous solutions. The adsorption isotherms and kinetics of both [RhCl5(H2O)]2- and [IrCl6]2- adsorption onto the sorbent materials are presented. The isothermal batch adsorption studies fitted the Freundlich model indicating heterogeneous surface adsorption. The Freundlich isotherm confirmed multilayer adsorption and the Freundlich constant (kf) displayed the following ascending order for nanofibers (F-QUAT EDA, F-QUAT TMDA, F-QUAT HMDA, F-QUAT OMDA and F-QUAT DMDA), silica microparticles (Si-QUAT EDA, Si-QUAT TMDA, Si-QUAT HMDA, Si-QUAT OMDA and Si-QUAT DMDA) and microspheres (B-QUAT EDA, B-QUAT TMDA, B-QUAT HMDA, B-QUAT OMDA and B-QUAT DMDA) and a decrease in kf for F-QUAT DDMDA, Si-QUAT DDMDA and B-QUAT DDMDA has been observed. The pseudo second-order model was found to be the best fit to describe the adsorption kinetics of both metal ions complexes onto all the sorbent materials. K2 value in pseudo second-order kinetics showed that the rate constant for adsorption of [IrCl6]2- onto nanofibers was larger than for silica microparticles and Merrifield microspheres. Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- was carried out and the loading capacities of [IrCl6]2- were obtained, and they showed dependence on the length of the methylene spacer between the two diammonium centres. [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The highest iridium loading capacities for all the sorbent materials for the diamines with decylene spacer, and were found to be 32.94 mg/g, 29.35 mg/g, and 27.09 mg/g for F-QUAT DMDA, Si-QUAT DMDA and B-QUAT DMDA respectively. It was also observed on the derivatives of DMDA supported on nanofibers that F-QUAT ethyl loading capacity for iridium (19.89 mg/g) reduced which may be due to the electron-donating nature of the ethyl group and the increase of hydrophobicity whereas F-QUAT benzyl loading capacity (244.64 mg/g) increased dramatically due to increase in the size of the cation which lowers the positive charge density of the quaternary diammonium center. The charge delocalizing ability of the benzyl group resulted in the best interaction of the diammonium group derived from this quaternizing agent, yielding the highest loading capacity for [IrCl6]2-. Reusability was conducted and the results showed that the all the sorbent materials can be used repeatedly without decreasing their adsorption capacity significantly. The neat diammonium salts were also synthesized and interacted with the chorido metal complex anions to form ion-pairs which were then studied for their solubility. The synthesis of the quaternary salts was rather challenging and resulted in some interesting species when impurities of the iodide form of the salts were present in the process of converting them to the iodide form. Some of these include I52+, which was confirmed preliminarily by X-ray structural analysis, potentiometry and cyclic voltammetry. Molecular modeling studies were also conducted to explain the interaction of the chlorido anions with the cationic diammonium centres, and to quantify these interactions by thermodynamic parameters, partial charge calculations, dipole moments and electrostatic potentials, and there was good agreement between theory and experiment. This thesis presents iridium-specific materials that could be applied in solutions of secondary PMGs sources containing rhodium and iridium as well as in feed solutions from ore processing.
- Full Text:
- Date Issued: 2014
- Authors: Majavu, Avela
- Date: 2014
- Subjects: Rhodium -- Separation , Iridium -- Separation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6576 , vital:21116
- Description: Poly(vinylbenzylchloride) (PVBC) nanofibers were fabricated by the electrospinning process. The Merrifield micropheres, silica microsparticles and PVBC nanofibers were functionalised with different quaternary diammonium groups derived from ethylenediamine (EDA), tetramethylenediamine (TMDA), hexamethylenediamine (HMDA), 1,8-diaminooctane (OMDA), 1,10-diaminodecane (DMDA) and 1,12-diaminododecane (DDMDA) and investigated for separation of [RhCl5(H2O)]2- and [IrCl6]2-. The sorbent materials were characterised by means of FTIR, XPS, SEM, BET surface area, thermogravimetric analysis and elemental analysis, and characterization results showed that the functionalization of the sorbent materials was successful. Batch equilibrium studies were carried out to assess the efficiency of these different anion exchangers using single metal aqueous solutions. The adsorption isotherms and kinetics of both [RhCl5(H2O)]2- and [IrCl6]2- adsorption onto the sorbent materials are presented. The isothermal batch adsorption studies fitted the Freundlich model indicating heterogeneous surface adsorption. The Freundlich isotherm confirmed multilayer adsorption and the Freundlich constant (kf) displayed the following ascending order for nanofibers (F-QUAT EDA, F-QUAT TMDA, F-QUAT HMDA, F-QUAT OMDA and F-QUAT DMDA), silica microparticles (Si-QUAT EDA, Si-QUAT TMDA, Si-QUAT HMDA, Si-QUAT OMDA and Si-QUAT DMDA) and microspheres (B-QUAT EDA, B-QUAT TMDA, B-QUAT HMDA, B-QUAT OMDA and B-QUAT DMDA) and a decrease in kf for F-QUAT DDMDA, Si-QUAT DDMDA and B-QUAT DDMDA has been observed. The pseudo second-order model was found to be the best fit to describe the adsorption kinetics of both metal ions complexes onto all the sorbent materials. K2 value in pseudo second-order kinetics showed that the rate constant for adsorption of [IrCl6]2- onto nanofibers was larger than for silica microparticles and Merrifield microspheres. Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- was carried out and the loading capacities of [IrCl6]2- were obtained, and they showed dependence on the length of the methylene spacer between the two diammonium centres. [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The highest iridium loading capacities for all the sorbent materials for the diamines with decylene spacer, and were found to be 32.94 mg/g, 29.35 mg/g, and 27.09 mg/g for F-QUAT DMDA, Si-QUAT DMDA and B-QUAT DMDA respectively. It was also observed on the derivatives of DMDA supported on nanofibers that F-QUAT ethyl loading capacity for iridium (19.89 mg/g) reduced which may be due to the electron-donating nature of the ethyl group and the increase of hydrophobicity whereas F-QUAT benzyl loading capacity (244.64 mg/g) increased dramatically due to increase in the size of the cation which lowers the positive charge density of the quaternary diammonium center. The charge delocalizing ability of the benzyl group resulted in the best interaction of the diammonium group derived from this quaternizing agent, yielding the highest loading capacity for [IrCl6]2-. Reusability was conducted and the results showed that the all the sorbent materials can be used repeatedly without decreasing their adsorption capacity significantly. The neat diammonium salts were also synthesized and interacted with the chorido metal complex anions to form ion-pairs which were then studied for their solubility. The synthesis of the quaternary salts was rather challenging and resulted in some interesting species when impurities of the iodide form of the salts were present in the process of converting them to the iodide form. Some of these include I52+, which was confirmed preliminarily by X-ray structural analysis, potentiometry and cyclic voltammetry. Molecular modeling studies were also conducted to explain the interaction of the chlorido anions with the cationic diammonium centres, and to quantify these interactions by thermodynamic parameters, partial charge calculations, dipole moments and electrostatic potentials, and there was good agreement between theory and experiment. This thesis presents iridium-specific materials that could be applied in solutions of secondary PMGs sources containing rhodium and iridium as well as in feed solutions from ore processing.
- Full Text:
- Date Issued: 2014
Some general convergence theorems on fixed points
- Authors: Panicker, Rekha Manoj
- Date: 2014
- Subjects: Fixed point theory , Convergence , Coincidence theory (Mathematics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5426 , http://hdl.handle.net/10962/d1013112
- Description: In this thesis, we first obtain coincidence and common fixed point theorems for a pair of generalized non-expansive type mappings in a normed space. Then we discuss two types of convergence theorems, namely, the convergence of Mann iteration procedures and the convergence and stability of fixed points. In addition, we discuss the viscosity approximations generated by (ψ ,ϕ)-weakly contractive mappings and a sequence of non-expansive mappings and then establish Browder and Halpern type convergence theorems on Banach spaces. With regard to iteration procedures, we obtain a result on the convergence of Mann iteration for generalized non-expansive type mappings in a Banach space which satisfies Opial's condition. And, in the case of stability of fixed points, we obtain a number of stability results for the sequence of (ψ,ϕ)- weakly contractive mappings and the sequence of their corresponding fixed points in metric and 2-metric spaces. We also present a generalization of Fraser and Nadler type stability theorems in 2-metric spaces involving a sequence of metrics.
- Full Text:
- Date Issued: 2014
- Authors: Panicker, Rekha Manoj
- Date: 2014
- Subjects: Fixed point theory , Convergence , Coincidence theory (Mathematics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5426 , http://hdl.handle.net/10962/d1013112
- Description: In this thesis, we first obtain coincidence and common fixed point theorems for a pair of generalized non-expansive type mappings in a normed space. Then we discuss two types of convergence theorems, namely, the convergence of Mann iteration procedures and the convergence and stability of fixed points. In addition, we discuss the viscosity approximations generated by (ψ ,ϕ)-weakly contractive mappings and a sequence of non-expansive mappings and then establish Browder and Halpern type convergence theorems on Banach spaces. With regard to iteration procedures, we obtain a result on the convergence of Mann iteration for generalized non-expansive type mappings in a Banach space which satisfies Opial's condition. And, in the case of stability of fixed points, we obtain a number of stability results for the sequence of (ψ,ϕ)- weakly contractive mappings and the sequence of their corresponding fixed points in metric and 2-metric spaces. We also present a generalization of Fraser and Nadler type stability theorems in 2-metric spaces involving a sequence of metrics.
- Full Text:
- Date Issued: 2014
Stakeholders' participation in curriculum development in four secondary schools in Fort Beaufort education district, Eastern cape province: towards a participatory curriculum model
- Authors: Obi, Uloma Nkpurunma
- Date: 2014
- Subjects: Curriculum planning Educational planning -- South Africa -- Eastern Cape Education -- Curricula -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10353/5840 , vital:29401
- Description: The new democratic government came to power in 1994 and one of its major missions was to change the system of education inherited from the apartheid regime by laying a foundation for a single national core syllabus to replace the erstwhile multi-tier system, which discriminated among racial groups. Under the apartheid regime, the curriculum was flawed by ‘racially, offensive and outdated content’ and the government embarked on a bold programme to cleanse it of these elements. The democratic government went about this through curriculum reforms. In 1997, it introduced Curriculum 2005 fondly called “C2005”, with the Outcome-based Education (OBE) principles. Despite the initial overwhelming support for C2005, it soon ran into trouble. In 2000, the Minister appointed a committee that reviewed the curriculum and in 2002, the Revised National Curriculum Statement (RNCS) was born. These curriculum reforms have been met with a lot of criticism and the government felt it was not serving its purpose. Some key stakeholders still felt that their non-involvement, non-participation and the lack of proper consultation in the curriculum process were partly responsible for teachers and subject advisers misinterpreting the curriculum and implementing it from their own perspectives. Subsequently, another review was done and the National Curriculum Statement (NCS) was launched in 2002. But the complaints did not cease, probably due to continuing poor performance at the Matric Examination which continues to feature low pass rates for many provinces, especially the Eastern Cape. Against this backdrop, the government streamlined the NCS curriculum yield, and an amended Curriculum and Assessment Policy Statement (CAPS) emerged. The key issue raised by critics is the lack of sufficient involvement of stakeholders in the curriculum review processes. At the same time, government continues to insist that it has been consulting adequately with all relevant stakeholders. There are iii obviously different interpretations of stakeholder involvement and participation and there is urgent need to reconcile whatever differences of opinion and definition exist, in order to gain common understanding, which is the first step in reaching a solution. For instance, how are the stakeholders involved? More importantly, what is meant by “involvement”? Even if there is no disagreement about the meaning of “involvement”, is the stage in the process at which the stakeholders are involved an important element in whether or not the process is an inclusive and participatory one?.
- Full Text:
- Date Issued: 2014
- Authors: Obi, Uloma Nkpurunma
- Date: 2014
- Subjects: Curriculum planning Educational planning -- South Africa -- Eastern Cape Education -- Curricula -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10353/5840 , vital:29401
- Description: The new democratic government came to power in 1994 and one of its major missions was to change the system of education inherited from the apartheid regime by laying a foundation for a single national core syllabus to replace the erstwhile multi-tier system, which discriminated among racial groups. Under the apartheid regime, the curriculum was flawed by ‘racially, offensive and outdated content’ and the government embarked on a bold programme to cleanse it of these elements. The democratic government went about this through curriculum reforms. In 1997, it introduced Curriculum 2005 fondly called “C2005”, with the Outcome-based Education (OBE) principles. Despite the initial overwhelming support for C2005, it soon ran into trouble. In 2000, the Minister appointed a committee that reviewed the curriculum and in 2002, the Revised National Curriculum Statement (RNCS) was born. These curriculum reforms have been met with a lot of criticism and the government felt it was not serving its purpose. Some key stakeholders still felt that their non-involvement, non-participation and the lack of proper consultation in the curriculum process were partly responsible for teachers and subject advisers misinterpreting the curriculum and implementing it from their own perspectives. Subsequently, another review was done and the National Curriculum Statement (NCS) was launched in 2002. But the complaints did not cease, probably due to continuing poor performance at the Matric Examination which continues to feature low pass rates for many provinces, especially the Eastern Cape. Against this backdrop, the government streamlined the NCS curriculum yield, and an amended Curriculum and Assessment Policy Statement (CAPS) emerged. The key issue raised by critics is the lack of sufficient involvement of stakeholders in the curriculum review processes. At the same time, government continues to insist that it has been consulting adequately with all relevant stakeholders. There are iii obviously different interpretations of stakeholder involvement and participation and there is urgent need to reconcile whatever differences of opinion and definition exist, in order to gain common understanding, which is the first step in reaching a solution. For instance, how are the stakeholders involved? More importantly, what is meant by “involvement”? Even if there is no disagreement about the meaning of “involvement”, is the stage in the process at which the stakeholders are involved an important element in whether or not the process is an inclusive and participatory one?.
- Full Text:
- Date Issued: 2014
Statistical modelling for detection of fraudulent activity on banking cards
- Authors: Nasila, Mark Wopicho
- Date: 2014
- Subjects: Mathematical statistics Mathematical models , Statistics Bank fraud
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/45887 , vital:39314
- Description: The current global recession has highlighted the fragile banking and related systems exposure to risks and acts of fraud. As a result of the ever changing information technology environment, where the internet has become an important retail sector channel, new fraud challenges are being encountered. The rapid growth in credit and cheque card transactions as a payment mechanism has led to an increase in card fraud. Approximately 70% of consumers utilising credit and cheque cards, as payment mechanisms, are significantly concerned about fraud (McAlearney, 2008). Additionally, credit card fraud has broader negative implications, such as funding organised crime, international narcotics trafficking and even the financing of terrorist activities. The first section of this study develops classification models that will improve on existing methods used to detect fraud and, as a result thereof, reduce the number of fraudulent transactions. Using confidential data obtained from a South African Bank, logistic regression and scoring techniques have been combined to develop a classification model that improves on the existing fraudulent identification methods. Using the methods developed in this study, a higher percentage of fraudulent transactions are classified correctly when compared to discriminant analysis, a method often used to identify fraudulent transactions. These models enable the banking business to identify demographic, socio-economic and banking-specific determinants which contribute significantly towards fraudulent transactions. The early detection methods will allow banks to put in place measures that will reduce the occurrence of fraudulent transactions on customer’s cards. The second section involves understanding how card holders and merchants contribute towards the occurrence of fraudulent incidents. This was achieved through two surveys which were carried out in the Johannesburg metropolitan area. These surveys aimed at understanding the perceptions of card holders and merchants with regard to aspects pertaining to card fraud contributed towards the occurrence of card fraud. Multinomial logistic regression (MLR) is used to classify card holders and merchants according to their likelihood of experiencing card fraud incidents. These results are based on their perceptions of certain aspects related to card fraud as obtained from the survey instruments.
- Full Text:
- Date Issued: 2014
- Authors: Nasila, Mark Wopicho
- Date: 2014
- Subjects: Mathematical statistics Mathematical models , Statistics Bank fraud
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/45887 , vital:39314
- Description: The current global recession has highlighted the fragile banking and related systems exposure to risks and acts of fraud. As a result of the ever changing information technology environment, where the internet has become an important retail sector channel, new fraud challenges are being encountered. The rapid growth in credit and cheque card transactions as a payment mechanism has led to an increase in card fraud. Approximately 70% of consumers utilising credit and cheque cards, as payment mechanisms, are significantly concerned about fraud (McAlearney, 2008). Additionally, credit card fraud has broader negative implications, such as funding organised crime, international narcotics trafficking and even the financing of terrorist activities. The first section of this study develops classification models that will improve on existing methods used to detect fraud and, as a result thereof, reduce the number of fraudulent transactions. Using confidential data obtained from a South African Bank, logistic regression and scoring techniques have been combined to develop a classification model that improves on the existing fraudulent identification methods. Using the methods developed in this study, a higher percentage of fraudulent transactions are classified correctly when compared to discriminant analysis, a method often used to identify fraudulent transactions. These models enable the banking business to identify demographic, socio-economic and banking-specific determinants which contribute significantly towards fraudulent transactions. The early detection methods will allow banks to put in place measures that will reduce the occurrence of fraudulent transactions on customer’s cards. The second section involves understanding how card holders and merchants contribute towards the occurrence of fraudulent incidents. This was achieved through two surveys which were carried out in the Johannesburg metropolitan area. These surveys aimed at understanding the perceptions of card holders and merchants with regard to aspects pertaining to card fraud contributed towards the occurrence of card fraud. Multinomial logistic regression (MLR) is used to classify card holders and merchants according to their likelihood of experiencing card fraud incidents. These results are based on their perceptions of certain aspects related to card fraud as obtained from the survey instruments.
- Full Text:
- Date Issued: 2014
Strength training and cardiovascular risk post-menses, with particular emphasis on the plasma lipoproteins: a controlled trial
- Authors: Viljoen, Janet Erica
- Date: 2014
- Subjects: Weight training for women -- Physiological aspects , Exercise for women -- Physiological aspects , Middle-aged women -- Health and hygiene , Cardiovascular system -- Diseases , Hypercholesteremia , Blood lipoproteins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5155 , http://hdl.handle.net/10962/d1013578
- Description: Introduction: Cardiovascular disease affects a greater proportion of females than it does males, and is responsible for an estimated 52 percent of female deaths per annum, globally. Due to the loss of oestrogen associated with the menopause, post-menopausal females are at elevated risk for hypercholesterolaemia which is a primary risk factor for cardiovascular disease. It has not yet been conclusively established whether resistance training can be used to ameliorate hypercholesterolaemia. Aim: This randomized controlled trial investigated what effect 12 weeks of progressive resistance training would have on plasma lipoproteins in a sample of post-menopausal females. Methods: Caucasian women (n=30 intervention and n=18 control) between the ages of 55 and 65 years who were not taking hormone replacement therapy were recruited. Participants did not smoke, were sedentary, were not taking any form of cholesterol-lowering medication, had at least one cholesterol abnormality at baseline but were otherwise healthy and able to participate in a strength training programme. Following extensive medical pre-screening, information dissemination and voluntary consent, the sample was divided into two groups. The exercise sample undertook 12 weeks of resistance training on five days of the week. The control group received no intervention. Measurements were obtained at baseline and every four weeks thereafter and included measures of strength, biochemistry (oestradiol, testosterone, full blood lipid profile, glycated haemoglobin and sex hormone binding globulin), anthropometry, morphology and self-reports (dietary intake, energy expenditure and the profile of mood states questionnaire). Results: There was no change to low density lipoprotein cholesterol, high density lipoprotein cholesterol, triglyceride content or total cholesterol as a result of the intervention. Back, chest and leg strength increased significantly (p<0.01) (increases of 51 percent, 35 percent and 43 percent respectively from baseline); waist circumference dropped (p<0.01) by 5 percent overall and diastolic blood pressure decreased significantly (-9 percent, p<0.01) in the exercise cohort but no change was noted in the matched control. Dietary intake, energy expenditure and body mass remained unchanged in both samples. Morphology (sum of skinfolds, estimated body fat content and girth measures) did not change and nor did other biochemical measures (HbA1c and sex hormone binding globulin) or hormone levels (oestradiol and testosterone). Despite the lack of overall change, an important finding was noted in individual results where a clear indication of ‘responders’ and ‘non-responders’ emerged. Conclusion: Overall mean results suggest that 12 weeks resistance training undertaken five days of the week was ineffective in reducing hypercholesterolaemia in this sample. Despite there being no identifying characteristics determined in this sample, evidence of responders and non-responders to the intervention indicates that reliance on mean data may not be sufficient when analysing data from exercise interventions. Therefore, while progressive resistance training had a positive effect on strength, waist circumference and diastolic blood pressure, it did not positively influence the plasma lipoproteins in this cohort of post-menopausal women. , Maiden name: Kelly, Janet Erica
- Full Text:
- Date Issued: 2014
- Authors: Viljoen, Janet Erica
- Date: 2014
- Subjects: Weight training for women -- Physiological aspects , Exercise for women -- Physiological aspects , Middle-aged women -- Health and hygiene , Cardiovascular system -- Diseases , Hypercholesteremia , Blood lipoproteins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5155 , http://hdl.handle.net/10962/d1013578
- Description: Introduction: Cardiovascular disease affects a greater proportion of females than it does males, and is responsible for an estimated 52 percent of female deaths per annum, globally. Due to the loss of oestrogen associated with the menopause, post-menopausal females are at elevated risk for hypercholesterolaemia which is a primary risk factor for cardiovascular disease. It has not yet been conclusively established whether resistance training can be used to ameliorate hypercholesterolaemia. Aim: This randomized controlled trial investigated what effect 12 weeks of progressive resistance training would have on plasma lipoproteins in a sample of post-menopausal females. Methods: Caucasian women (n=30 intervention and n=18 control) between the ages of 55 and 65 years who were not taking hormone replacement therapy were recruited. Participants did not smoke, were sedentary, were not taking any form of cholesterol-lowering medication, had at least one cholesterol abnormality at baseline but were otherwise healthy and able to participate in a strength training programme. Following extensive medical pre-screening, information dissemination and voluntary consent, the sample was divided into two groups. The exercise sample undertook 12 weeks of resistance training on five days of the week. The control group received no intervention. Measurements were obtained at baseline and every four weeks thereafter and included measures of strength, biochemistry (oestradiol, testosterone, full blood lipid profile, glycated haemoglobin and sex hormone binding globulin), anthropometry, morphology and self-reports (dietary intake, energy expenditure and the profile of mood states questionnaire). Results: There was no change to low density lipoprotein cholesterol, high density lipoprotein cholesterol, triglyceride content or total cholesterol as a result of the intervention. Back, chest and leg strength increased significantly (p<0.01) (increases of 51 percent, 35 percent and 43 percent respectively from baseline); waist circumference dropped (p<0.01) by 5 percent overall and diastolic blood pressure decreased significantly (-9 percent, p<0.01) in the exercise cohort but no change was noted in the matched control. Dietary intake, energy expenditure and body mass remained unchanged in both samples. Morphology (sum of skinfolds, estimated body fat content and girth measures) did not change and nor did other biochemical measures (HbA1c and sex hormone binding globulin) or hormone levels (oestradiol and testosterone). Despite the lack of overall change, an important finding was noted in individual results where a clear indication of ‘responders’ and ‘non-responders’ emerged. Conclusion: Overall mean results suggest that 12 weeks resistance training undertaken five days of the week was ineffective in reducing hypercholesterolaemia in this sample. Despite there being no identifying characteristics determined in this sample, evidence of responders and non-responders to the intervention indicates that reliance on mean data may not be sufficient when analysing data from exercise interventions. Therefore, while progressive resistance training had a positive effect on strength, waist circumference and diastolic blood pressure, it did not positively influence the plasma lipoproteins in this cohort of post-menopausal women. , Maiden name: Kelly, Janet Erica
- Full Text:
- Date Issued: 2014
Structural, optical and electrical characterization of nano-sized c-tio2 quamtum dots synthesized by spray pyrolysis
- Authors: Taziwa, Raymond Tichaona
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11342 , http://hdl.handle.net/10353/d1016089
- Description: In the 21st century, scientific communities face challenges and opportunities concerning future development, where innovations must be a key driver over the past, evolution of African societies were based on incomplete models, only taking into account economical growth and not paying attention to environmental deterioration as a consequence of anthropogenic activity and environmental pollution. We have to learn from our past mistakes in order not to repeat them. Education and research of today as the embryonic stages of the development models of tomorrow should be directed toward a sustainable mentality. In this sense, solar energy technologies have emerged as key instruments for minimizing environmental impact as well as reducing economic cost in the field of renewable energies. Titanium dioxide is a fascinating low cost material exhibiting unique properties of stability and photo catalytic activities, leading to clean technologies in water purification and energy conversion of sunlight. However, conventional techniques (high temperature, high vacuum, high pressures) of processing titanium dioxide are a technological limitation due to excessive energy consumption. This poses a handicap for practical applications in areas such as preparation of hybrid organic/Titanium dioxide materials or devices on thermo flexible substrates such as plastic material. It is for this reason that the investigation presented in this Ph.D thesis deals with the development of spray pyrolysis techniques for preparation of carbon doped titanium dioxide nano powders for solar cell applications. This thesis is therefore structured as follows: Chapter 1 gives a general overview of the work done in this thesis. This work relies greatly on the excellent structural optical and electrical properties of TiO2 thin films, as well as its chemical resistance and insulating properties. A summary of the physical, optical, electrical and chemical properties reported in the literature, with an emphasis on those relevant to solar cell fabrication, is presented in Chapter 2. Chapter 3 gives a concise literature review on models governing droplet formation in ultrasonic spray pyrolysis (USP) techniques, the limitations of these models have been exposed and a new relation model for estimating the final particle size given a set of initial reaction conditions has been proposed. The presently derived model is quite advantageous in that it does not require the investigator to look up values of surface tension and density for every precursor solution. Chapter 4 presents in detail the designed and constructed spray pyrolysis system capable of realizing desired nano structures for photovoltaic applications. The first system employed an ultrasonic atomization spray nozzle in order to create an aerosol of the TiO2 precursor. The reasons for choosing ultrasonic spray deposition (USP) and the TiO2 precursors, titanium iso propoxide and titanium tetra butoxide are discussed. Chapter 5 outlines experimental methodologies used in synthesis and characterization of the materials used in this study. Chapter 5 further provides experimental methodologies used in fabrication of a new type of photo electrochemical solar cells (PECs). Chapter 6 reveals the opto-electrical results of PECs solar cells fabricated. There are numerous properties that are affected by the size but emphasis will be placed on nano-size and confinement effects. Chapter 7 presents a confirmation of the phonon confinement effects in C-TiO2 QDs for the first time. In addition Chapter 7 also presents a new phonon confinement model. Chapter 8 reveals the optical, structural and electronic properties of C-TiO2 QDs synthesized by USP and PSP techniques. In addition the electrical properties of C-TiO2 QDs PEC solar cells devices are reported in Chapter 8. Concluding remarks, with potential future research projects are presented in Chapter 9. Through these 9 chapters, all research questions have been answered satisfactorily and all objectives met. Most of the work contained in this thesis has been subjected to external reviews through publication of these peer reviewed articles.
- Full Text:
- Date Issued: 2014
- Authors: Taziwa, Raymond Tichaona
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11342 , http://hdl.handle.net/10353/d1016089
- Description: In the 21st century, scientific communities face challenges and opportunities concerning future development, where innovations must be a key driver over the past, evolution of African societies were based on incomplete models, only taking into account economical growth and not paying attention to environmental deterioration as a consequence of anthropogenic activity and environmental pollution. We have to learn from our past mistakes in order not to repeat them. Education and research of today as the embryonic stages of the development models of tomorrow should be directed toward a sustainable mentality. In this sense, solar energy technologies have emerged as key instruments for minimizing environmental impact as well as reducing economic cost in the field of renewable energies. Titanium dioxide is a fascinating low cost material exhibiting unique properties of stability and photo catalytic activities, leading to clean technologies in water purification and energy conversion of sunlight. However, conventional techniques (high temperature, high vacuum, high pressures) of processing titanium dioxide are a technological limitation due to excessive energy consumption. This poses a handicap for practical applications in areas such as preparation of hybrid organic/Titanium dioxide materials or devices on thermo flexible substrates such as plastic material. It is for this reason that the investigation presented in this Ph.D thesis deals with the development of spray pyrolysis techniques for preparation of carbon doped titanium dioxide nano powders for solar cell applications. This thesis is therefore structured as follows: Chapter 1 gives a general overview of the work done in this thesis. This work relies greatly on the excellent structural optical and electrical properties of TiO2 thin films, as well as its chemical resistance and insulating properties. A summary of the physical, optical, electrical and chemical properties reported in the literature, with an emphasis on those relevant to solar cell fabrication, is presented in Chapter 2. Chapter 3 gives a concise literature review on models governing droplet formation in ultrasonic spray pyrolysis (USP) techniques, the limitations of these models have been exposed and a new relation model for estimating the final particle size given a set of initial reaction conditions has been proposed. The presently derived model is quite advantageous in that it does not require the investigator to look up values of surface tension and density for every precursor solution. Chapter 4 presents in detail the designed and constructed spray pyrolysis system capable of realizing desired nano structures for photovoltaic applications. The first system employed an ultrasonic atomization spray nozzle in order to create an aerosol of the TiO2 precursor. The reasons for choosing ultrasonic spray deposition (USP) and the TiO2 precursors, titanium iso propoxide and titanium tetra butoxide are discussed. Chapter 5 outlines experimental methodologies used in synthesis and characterization of the materials used in this study. Chapter 5 further provides experimental methodologies used in fabrication of a new type of photo electrochemical solar cells (PECs). Chapter 6 reveals the opto-electrical results of PECs solar cells fabricated. There are numerous properties that are affected by the size but emphasis will be placed on nano-size and confinement effects. Chapter 7 presents a confirmation of the phonon confinement effects in C-TiO2 QDs for the first time. In addition Chapter 7 also presents a new phonon confinement model. Chapter 8 reveals the optical, structural and electronic properties of C-TiO2 QDs synthesized by USP and PSP techniques. In addition the electrical properties of C-TiO2 QDs PEC solar cells devices are reported in Chapter 8. Concluding remarks, with potential future research projects are presented in Chapter 9. Through these 9 chapters, all research questions have been answered satisfactorily and all objectives met. Most of the work contained in this thesis has been subjected to external reviews through publication of these peer reviewed articles.
- Full Text:
- Date Issued: 2014
Study of the interrelationship between weld geometry, process variables and joint intergrity for friction processed AA6082-T6 aluminium
- Authors: Samuel, Darren Alton Graham
- Date: 2014
- Subjects: Friction welding -- Research Pressure welding , Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/48058 , vital:40467
- Description: This work presents a broad overview of the successful development of friction taper stud welding (FTSW) in 25mm thick AA6082-T6 sections. It covers the selection of geometry and process parameters, the development of data logging equipment, energy input results and interpretations. Research was carried out to develop the FTSW process for application in 25mm AA6082-T6 sections. The development and application of the FTSW process addresses the need to fill blind holes in thick aluminium sections for the repair of incorrectly drilled holes, friction stir welding exit holes and defects in critical components. During welding, frictional torque, rotational speed, axial force, near interface temperature of the tapered hole and welding time was recorded. This data was used to calculate energy input and energy input rates throughout a weld, enabling the effect of process parameters to be linked to energy, temperature, microhardness and static joint strength. Results of preliminary experiments are included in the study that were used for the design of a process parameter test window for FTSW in AA6082-T6, as no parameters were available to indicate a starting point for the research. The effect of process parameters on the static joint strength at the base of the tapered hole are presented; using a parallel sided stud and tapered hole configuration. This addresses one of the pressing issues facing FTSW of AA6082-T6, namely the lack of bonding at the bottom of the blind hole. A final process parameter matrix is designed based on the process development welds and is presented and discussed. In addition, the use of a non-consumable heat sink was investigated to prevent the premature collapse of the stud during welding and was shown to be critically important to the FTSW of AA6082-T6. To achieve good sidewall bonding a hole taper angle of 60° is required, this having been shown during visual evaluation of development welds. Stud taper angles between 2° and 5° less than the taper angle of the hole were identified as the range within which good FTSW can be made. With this geometry, at no stage during welding did the body of the stud shear off from the weld interface due to softening, thereby preventing collapse of the stud and formation of poorly bonded regions at the sidewall of the hole. The absence of shearing off of the weld interface during plunge was shown to be a good indicator of appropriate geometry and can be linked to welds made with high hole and stud taper angles and high axial force ramp up rates. The large hole and stud diameter relative to the depth of the hole and the large taper angle of the hole further aid in keeping the weld nugget rotating in the hole, promoting plasticization of the sidewall. Axial force ramp up rate was found to be the main critical success factor in an AA6082-T6 FTSW. Without control of this parameter the body of the stud will heat and detrimentally soften during plunge. It was established that good FTSW in AA6082-T6 cannot be made without the use of preheat to overcome the heat dissipation during welding, and is directly linked to improved energy input characteristics. Energy input as well as energy input rate were directly linked to static tensile strength and softening in the HAZ. The angle of the stud has been related to the energy input rate limit of the stud body, with increasing stud taper angles enabling the stud to withstand a higher energy input rate, allowing the weld interface to propagate up the hole at a slower rate, promoting plasticization of the sidewall. This study has successfully made good FTSW in 25mm thick AA6082-T6, in a 60°, 20mm deep tapered hole. Process parameters and ranges that produce FTSW exhibiting the required characteristics were identified by this study.
- Full Text:
- Date Issued: 2014
- Authors: Samuel, Darren Alton Graham
- Date: 2014
- Subjects: Friction welding -- Research Pressure welding , Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/48058 , vital:40467
- Description: This work presents a broad overview of the successful development of friction taper stud welding (FTSW) in 25mm thick AA6082-T6 sections. It covers the selection of geometry and process parameters, the development of data logging equipment, energy input results and interpretations. Research was carried out to develop the FTSW process for application in 25mm AA6082-T6 sections. The development and application of the FTSW process addresses the need to fill blind holes in thick aluminium sections for the repair of incorrectly drilled holes, friction stir welding exit holes and defects in critical components. During welding, frictional torque, rotational speed, axial force, near interface temperature of the tapered hole and welding time was recorded. This data was used to calculate energy input and energy input rates throughout a weld, enabling the effect of process parameters to be linked to energy, temperature, microhardness and static joint strength. Results of preliminary experiments are included in the study that were used for the design of a process parameter test window for FTSW in AA6082-T6, as no parameters were available to indicate a starting point for the research. The effect of process parameters on the static joint strength at the base of the tapered hole are presented; using a parallel sided stud and tapered hole configuration. This addresses one of the pressing issues facing FTSW of AA6082-T6, namely the lack of bonding at the bottom of the blind hole. A final process parameter matrix is designed based on the process development welds and is presented and discussed. In addition, the use of a non-consumable heat sink was investigated to prevent the premature collapse of the stud during welding and was shown to be critically important to the FTSW of AA6082-T6. To achieve good sidewall bonding a hole taper angle of 60° is required, this having been shown during visual evaluation of development welds. Stud taper angles between 2° and 5° less than the taper angle of the hole were identified as the range within which good FTSW can be made. With this geometry, at no stage during welding did the body of the stud shear off from the weld interface due to softening, thereby preventing collapse of the stud and formation of poorly bonded regions at the sidewall of the hole. The absence of shearing off of the weld interface during plunge was shown to be a good indicator of appropriate geometry and can be linked to welds made with high hole and stud taper angles and high axial force ramp up rates. The large hole and stud diameter relative to the depth of the hole and the large taper angle of the hole further aid in keeping the weld nugget rotating in the hole, promoting plasticization of the sidewall. Axial force ramp up rate was found to be the main critical success factor in an AA6082-T6 FTSW. Without control of this parameter the body of the stud will heat and detrimentally soften during plunge. It was established that good FTSW in AA6082-T6 cannot be made without the use of preheat to overcome the heat dissipation during welding, and is directly linked to improved energy input characteristics. Energy input as well as energy input rate were directly linked to static tensile strength and softening in the HAZ. The angle of the stud has been related to the energy input rate limit of the stud body, with increasing stud taper angles enabling the stud to withstand a higher energy input rate, allowing the weld interface to propagate up the hole at a slower rate, promoting plasticization of the sidewall. This study has successfully made good FTSW in 25mm thick AA6082-T6, in a 60°, 20mm deep tapered hole. Process parameters and ranges that produce FTSW exhibiting the required characteristics were identified by this study.
- Full Text:
- Date Issued: 2014
Sustainable governance management systems: a practical approach for Water Boards in South Africa
- Authors: Ntili, Tseliso Paul
- Date: 2014
- Subjects: South Africa. Department of Water Affairs and Forestry , Water-supply -- South Africa -- Management , Water quality -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/9185 , vital:26472
- Description: This research study explored the appropriate sustainable governance management systems for South African socio-economic conditions. This was achieved by investigating the current governance and management of water boards in performing their business and water services provisioning at municipal level. Municipalities are the third sphere of government in South Africa and are found at local levels of governance. They are businesses that provide running water as legislated by the Constitution of the Republic of South Africa, 1996. Water boards are public institutions established in terms of the Water Services Act, 108 of 1997 (WSA) and listed as Schedule 3 part B: National Government Business Enterprise in terms of the Public Finance Management Act 29 of 1999. They are accountable to the national government through the Department of Water Affairs. Their responsibility is to support municipalities where water-provisioning challenges are eminent. They report annually to national parliament on their performance within a specific financial year. Water boards are currently able to perform their operations in selected jurisdictions as contracted by municipalities. They are struggling in managing and governing their water business while striving to achieve improvements in water service coverage, operating efficiency and service delivery. The aim of the research study was to investigate areas affecting the sustainability of governance management systems for water boards in relation to the improvement of service delivery in South Africa. The analysis of age and gender factors and the conditions affecting governance are explored. The research used the qualitative and quantitative methods to analyse the research questions. Prior to the commencement of the study, the researcher performed an intensive desktop study involving the use of dated and recently published material related to governance and management of the water institutions in developed and developing countries. During the desktop study, national and international accredited journals were prioritised to obtain related and relevant similar information to the water governance and management of water institutions. In addition, a case study was undertaken in Ficksburg in which water boards provided an intervention in resolving the water crisis, since the provision of water is a basic service at local government. This area experienced both water shortage and a poor quality of water. With regard to qualitative methodology, participatory forums were used to delineate the research context and premise. The study population consisted of individuals who were in the business of water boards with special reference to water management and board of directors for a population of 1 000. Of the 500 questionnaires sent out, 419 were returned. The data were analysed using the statistical software package, Statistical Package for Social Sciences (SPSS). The results and recommendations are presented based on the identified objectives of the study. The study’s findings provide information for transformation and improvement in the performance of water boards in South Africa when striving for sustainability in management and governance. The findings reveal the need for improvements in the involvement of females in the business of the water boards. The findings confirm the outcomes of previous studies regarding the slow implementation of affirmative action and transformation processes as required by legislation. Furthermore, the results reveal that the factors and conditions affecting sustainability of the water boards need to be prioritised to improve the management and governance aspects of water boards. These include the appropriate selection of members of the boards of directors, water boards' committees that are guided by legislation in their operations and the maintenance of proper financial management (collection of revenue, implementation of appropriate financial strategies and striving for positive clean audit). Water boards are encouraged to strengthen their intergovernmental relations in order to make their mandate known across all spheres of government. Service delivery should be approached “from source to tap and tap to source” to promote high-quality provision of water. The water boards should be accountable to the municipalities for the provision of delegated operations. The Department of Water Affairs exercises an oversight role to ensure the sustainable provision of the services. However, the study concludes that without a strong management and a sustainable governance approach, water boards will not be able to carry out its water developmental mandate. The practical framework that was developed in this study provides management and governance tools for sustained provisioning of water to advance transformational and developmental needs and the application of legislations. The results in the study have a direct impact on the codes of practice and regulations on employment equity in implementing the Employment Equity Act of 1998, Intergovernmental Relations Act of 2005, Companies Act of 2008, National Water Act of 1998, and Water Services Act of 1997. Therefore, the practical implementation of this framework will enhance water as a transformational and developmental feature in addressing the social, environmental and economic services.
- Full Text:
- Date Issued: 2014
- Authors: Ntili, Tseliso Paul
- Date: 2014
- Subjects: South Africa. Department of Water Affairs and Forestry , Water-supply -- South Africa -- Management , Water quality -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/9185 , vital:26472
- Description: This research study explored the appropriate sustainable governance management systems for South African socio-economic conditions. This was achieved by investigating the current governance and management of water boards in performing their business and water services provisioning at municipal level. Municipalities are the third sphere of government in South Africa and are found at local levels of governance. They are businesses that provide running water as legislated by the Constitution of the Republic of South Africa, 1996. Water boards are public institutions established in terms of the Water Services Act, 108 of 1997 (WSA) and listed as Schedule 3 part B: National Government Business Enterprise in terms of the Public Finance Management Act 29 of 1999. They are accountable to the national government through the Department of Water Affairs. Their responsibility is to support municipalities where water-provisioning challenges are eminent. They report annually to national parliament on their performance within a specific financial year. Water boards are currently able to perform their operations in selected jurisdictions as contracted by municipalities. They are struggling in managing and governing their water business while striving to achieve improvements in water service coverage, operating efficiency and service delivery. The aim of the research study was to investigate areas affecting the sustainability of governance management systems for water boards in relation to the improvement of service delivery in South Africa. The analysis of age and gender factors and the conditions affecting governance are explored. The research used the qualitative and quantitative methods to analyse the research questions. Prior to the commencement of the study, the researcher performed an intensive desktop study involving the use of dated and recently published material related to governance and management of the water institutions in developed and developing countries. During the desktop study, national and international accredited journals were prioritised to obtain related and relevant similar information to the water governance and management of water institutions. In addition, a case study was undertaken in Ficksburg in which water boards provided an intervention in resolving the water crisis, since the provision of water is a basic service at local government. This area experienced both water shortage and a poor quality of water. With regard to qualitative methodology, participatory forums were used to delineate the research context and premise. The study population consisted of individuals who were in the business of water boards with special reference to water management and board of directors for a population of 1 000. Of the 500 questionnaires sent out, 419 were returned. The data were analysed using the statistical software package, Statistical Package for Social Sciences (SPSS). The results and recommendations are presented based on the identified objectives of the study. The study’s findings provide information for transformation and improvement in the performance of water boards in South Africa when striving for sustainability in management and governance. The findings reveal the need for improvements in the involvement of females in the business of the water boards. The findings confirm the outcomes of previous studies regarding the slow implementation of affirmative action and transformation processes as required by legislation. Furthermore, the results reveal that the factors and conditions affecting sustainability of the water boards need to be prioritised to improve the management and governance aspects of water boards. These include the appropriate selection of members of the boards of directors, water boards' committees that are guided by legislation in their operations and the maintenance of proper financial management (collection of revenue, implementation of appropriate financial strategies and striving for positive clean audit). Water boards are encouraged to strengthen their intergovernmental relations in order to make their mandate known across all spheres of government. Service delivery should be approached “from source to tap and tap to source” to promote high-quality provision of water. The water boards should be accountable to the municipalities for the provision of delegated operations. The Department of Water Affairs exercises an oversight role to ensure the sustainable provision of the services. However, the study concludes that without a strong management and a sustainable governance approach, water boards will not be able to carry out its water developmental mandate. The practical framework that was developed in this study provides management and governance tools for sustained provisioning of water to advance transformational and developmental needs and the application of legislations. The results in the study have a direct impact on the codes of practice and regulations on employment equity in implementing the Employment Equity Act of 1998, Intergovernmental Relations Act of 2005, Companies Act of 2008, National Water Act of 1998, and Water Services Act of 1997. Therefore, the practical implementation of this framework will enhance water as a transformational and developmental feature in addressing the social, environmental and economic services.
- Full Text:
- Date Issued: 2014
Swift heavy ion radiation damage in nanocrystalline ZrN
- Authors: Janse van Vuuren, Arno
- Date: 2014
- Subjects: Zirconium -- Effect of radiation on , Nanocrystals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10550 , http://hdl.handle.net/10948/d1020147
- Description: ZrN has been identified as a candidate material for use as an inert matrix fuel host for the transmutation of plutonium and minor actinides. These materials will be subjected to large amounts of different types of radiation within the nuclear reactor core. The types of radiation include fission fragments and alpha-particles amongst others. Recent studies suggest that nanocrystalline material may have a higher radiation tolerance than their polycrystalline and bulk counterparts. Some studies have shown that swift heavy ion irradiation may also significantly modulate hydrogen and helium behaviour in materials. This phenomenon is also of considerable practical interest for inert matrix fuel hosts, since these materials accumulate helium via (n,) reactions and will also be subjected to irradiation by fission fragments. The aim of this investigation is therefore to study the effects of fission fragment and alpha particle irradiation on nanocrystalline ZrN. In an effort to simulate the effects of fission fragments on nanocrystalline zirconium nitride different layers (on a Si substrate) of various thicknesses (0.1, 3, 10 and 20 μm) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 31012 to 2.61015 cm-2 for Xe, 1×1013 to 7.06×1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of this irradiation is to simulate the effects of fission fragments on nanocrystalline ZrN. In order to simulate the effects of alpha particles and the combined effects of alpha particles and fission fragments on nanocrystalline ZrN it was irradiated with 30 keV He to fluences between 1016 and 5×1016 cm-2, 167 MeV Xe to fluences between 5×1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5×1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C. The different irradiated layers were subsequently analysed via X-ray diffraction (XRD), μ-Raman, transmission electron microscopy (TEM) and nano indentation hardness testing (NIH) techniques. XRD, TEM, μ-Raman and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation. The microstructure of nanocrystalline ZrN remains unaffected by electronic excitation effects even at a very high stopping power. TEM and SEM results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. Results from He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects, but this is possibly due to the lower fluence of Bi ions. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.
- Full Text:
- Date Issued: 2014
- Authors: Janse van Vuuren, Arno
- Date: 2014
- Subjects: Zirconium -- Effect of radiation on , Nanocrystals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10550 , http://hdl.handle.net/10948/d1020147
- Description: ZrN has been identified as a candidate material for use as an inert matrix fuel host for the transmutation of plutonium and minor actinides. These materials will be subjected to large amounts of different types of radiation within the nuclear reactor core. The types of radiation include fission fragments and alpha-particles amongst others. Recent studies suggest that nanocrystalline material may have a higher radiation tolerance than their polycrystalline and bulk counterparts. Some studies have shown that swift heavy ion irradiation may also significantly modulate hydrogen and helium behaviour in materials. This phenomenon is also of considerable practical interest for inert matrix fuel hosts, since these materials accumulate helium via (n,) reactions and will also be subjected to irradiation by fission fragments. The aim of this investigation is therefore to study the effects of fission fragment and alpha particle irradiation on nanocrystalline ZrN. In an effort to simulate the effects of fission fragments on nanocrystalline zirconium nitride different layers (on a Si substrate) of various thicknesses (0.1, 3, 10 and 20 μm) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 31012 to 2.61015 cm-2 for Xe, 1×1013 to 7.06×1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of this irradiation is to simulate the effects of fission fragments on nanocrystalline ZrN. In order to simulate the effects of alpha particles and the combined effects of alpha particles and fission fragments on nanocrystalline ZrN it was irradiated with 30 keV He to fluences between 1016 and 5×1016 cm-2, 167 MeV Xe to fluences between 5×1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5×1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C. The different irradiated layers were subsequently analysed via X-ray diffraction (XRD), μ-Raman, transmission electron microscopy (TEM) and nano indentation hardness testing (NIH) techniques. XRD, TEM, μ-Raman and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation. The microstructure of nanocrystalline ZrN remains unaffected by electronic excitation effects even at a very high stopping power. TEM and SEM results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. Results from He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects, but this is possibly due to the lower fluence of Bi ions. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.
- Full Text:
- Date Issued: 2014
Synthesis, characterization, and biological studies of pyrazolone Schiff bases and their transition metal complexes
- Authors: Idemudia, Omoruyi Gold
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11340 , http://hdl.handle.net/10353/d1016068
- Description: Some new acylpyrazolone Schiff bases have been synthesized from the condensation reaction of two acylpyrazolone diketone precursors with phenylhydrazine, 2,4-dinitrophenylhydrazine and sulfanilamide. They have been fully characterized by elemental analysis and spectroscopic techniques (IR,1H and 13C NMR, and mass-spectra). The single crystal structure of the benzoyl derivative acylpyrazolone Schiff bases have been obtained and analyzed by X-ray crystallography technique. Solid state X-ray diffraction revealed a keto tautomer Schiff base in solid state. Mn(II), Co(II), Ni(II) and Cu(II) complexes with the Schiff bases have been synthesized and characterized by elemental analysis, IR and UV-VIS spectroscopy, magnetic susceptibility measurements, and thermal studies (TGA and DTG). An octahedral geometry around the transition metal ion, consisting of two bidentate Schiff base ligands bonding through the azometine nitrogen and ketonic oxygen have been proposed based on careful interpretation of available analytical and spectroscopic characterization results. Two water molecules as ligands complete the octahedral geometry in all cases. Using the invitro disc diffusion method for screening synthesized compounds against selected gram positive and gram negative bacterial at 40 mg/mL, and the DPPH free radical scavenging methods at 0.50, 0.25 and 0.13 mg/mL, the synthesized Schiff base and metal complexes showed varying biological activities. 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one sul29 fanilamide showed more activity generally, exhibiting a broad spectrum activity against all selected bacterial in some cases. Mn(II), Co(II) and Ni(II) complexes of sulfanilamide Schiff base with the acetylpyrazolone derivative 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one sulfanilamide, exhibited a stronger and very good DPPH radical scavenging activity as good as ascorbic acid on comparing, but not with Cu(II). As such they could be important antitumour candidates.
- Full Text:
- Date Issued: 2014
- Authors: Idemudia, Omoruyi Gold
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11340 , http://hdl.handle.net/10353/d1016068
- Description: Some new acylpyrazolone Schiff bases have been synthesized from the condensation reaction of two acylpyrazolone diketone precursors with phenylhydrazine, 2,4-dinitrophenylhydrazine and sulfanilamide. They have been fully characterized by elemental analysis and spectroscopic techniques (IR,1H and 13C NMR, and mass-spectra). The single crystal structure of the benzoyl derivative acylpyrazolone Schiff bases have been obtained and analyzed by X-ray crystallography technique. Solid state X-ray diffraction revealed a keto tautomer Schiff base in solid state. Mn(II), Co(II), Ni(II) and Cu(II) complexes with the Schiff bases have been synthesized and characterized by elemental analysis, IR and UV-VIS spectroscopy, magnetic susceptibility measurements, and thermal studies (TGA and DTG). An octahedral geometry around the transition metal ion, consisting of two bidentate Schiff base ligands bonding through the azometine nitrogen and ketonic oxygen have been proposed based on careful interpretation of available analytical and spectroscopic characterization results. Two water molecules as ligands complete the octahedral geometry in all cases. Using the invitro disc diffusion method for screening synthesized compounds against selected gram positive and gram negative bacterial at 40 mg/mL, and the DPPH free radical scavenging methods at 0.50, 0.25 and 0.13 mg/mL, the synthesized Schiff base and metal complexes showed varying biological activities. 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one sul29 fanilamide showed more activity generally, exhibiting a broad spectrum activity against all selected bacterial in some cases. Mn(II), Co(II) and Ni(II) complexes of sulfanilamide Schiff base with the acetylpyrazolone derivative 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one sulfanilamide, exhibited a stronger and very good DPPH radical scavenging activity as good as ascorbic acid on comparing, but not with Cu(II). As such they could be important antitumour candidates.
- Full Text:
- Date Issued: 2014
Synthetic analogues of marine bisindole alkaloids as potent selective inhibitors of MRSA pyruvate kinase
- Veale, Clinton Gareth Lancaster
- Authors: Veale, Clinton Gareth Lancaster
- Date: 2014 , 2014-04-02
- Subjects: Alkaloids , Pyruvate kinase , Staphylococcus aureus , Antibiotics , Sponges -- South Africa , Imidazoles , Biological assay , Antibacterial agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4563 , http://hdl.handle.net/10962/d1020893
- Description: Globally, methicillin resistant Staphylococcus aureus (MRSA) has become increasingly difficult to manage in the clinic and new antibiotics are required. The structure activity relationship (SAR) study presented in this thesis forms part of an international collaborative effort to identify potent and selective inhibitors of an MRSA pyruvate kinase (PK) enzyme target. In earlier work the known marine natural product bromodeoxytopsentin (1.6), isolated from a South African marine sponge Topsentia pachastrelloides, exhibited selective and significant inhibition of MRSA PK (IC₅₀ 60 nM). Accordingly bromodeoxytopsentin provided the initial chemical scaffold around which our SAR study was developed. Following a comprehensive introduction, providing the necessary background to the research described in subsequent Chapters, this thesis has been divided into three major parts. Part one (Chapter 2) documents the synthesis of two natural imidazole containing topsentin analogues 1.40, 1.46, five new synthetic analogues 1.58—1.61, 2.104. In the process we developed a new method for the synthesis of topsentin derivatives via selenium dioxide mediated oxidation of N-Boc protected 3-acetylindoles to yield glyoxal intermediates which were subsequently cyclized and deprotected to yield the desired products. Interestingly we were able to demonstrate a delicate relationship between the relative equivalents of selenium dioxide and water used during the oxidation step, careful manipulation of which was required to prevent the uncontrolled formation of side products. Synthetic compounds 1.40, 1.46, 1.58—1.61 were found to be potent inhibitors of MRSA PK (IC₅₀ 238, 2.1, 23, 1.4, 6.3 and 3.2 nM respectively) with 1000-10000 fold selectivity for MRSA PK over four human orthologs. In the second part of this thesis (Chapter 3) we report the successful synthesis of a cohort of previously unknown thiazole containing bisindole topsentin analogues 1.62—1.68 via a Hantzsch thiazole synthesis. Bioassay results revealed that these compounds were only moderate inhibitors of MRSA PK (IC₅₀ 5.1—20 μM) which suggested that inhibitory activity was significantly reduced upon substitution of the central imidazole ring of topsentin type analogues with a thiazole type ring. In addition in Chapter 3 we describe unsuccessful attempts to regiospecifically synthesize oxazole and imidazole topsentin analogues through a similar Hantzsch method. As a consequence of our efforts in this regard we investigated three key reactions in depth, namely the synthesis of 2.2, 3.38, 3.40, 3.41 via α-bromination of 3-acetylindole and the synthesis of indolyl-3-carbonylnitriles 2.13, 3.45—3.47 and α-oxo-1H-indole-3-thioacetamides 3.48—3.51. The investigation of the latter led to the isolation and elucidation of two anomalous N,N-dimethyl-1H-indole-3-carboxamides 3.52 and 3.53. Finally the third part of this thesis (Chapter 4) deals with in silico assessment of the binding of both the imidazole and thiazole containing bisindole alkaloids to the MRSA PK protein which initially guided our SAR studies. In this chapter we reveal that there appears to be no correlation between in silico binding predictions and in vitro MRSA PK inhibitory bioassay data. Superficially it seems that binding energy as determined by the docking program used for these studies correlated with the size of the indole substituents and did not reflect IC₅₀ MRSA PK inhibitory data. Although this led us to computationally explore possible alternative binding sites no clear alternative has been identified.
- Full Text:
- Date Issued: 2014
- Authors: Veale, Clinton Gareth Lancaster
- Date: 2014 , 2014-04-02
- Subjects: Alkaloids , Pyruvate kinase , Staphylococcus aureus , Antibiotics , Sponges -- South Africa , Imidazoles , Biological assay , Antibacterial agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4563 , http://hdl.handle.net/10962/d1020893
- Description: Globally, methicillin resistant Staphylococcus aureus (MRSA) has become increasingly difficult to manage in the clinic and new antibiotics are required. The structure activity relationship (SAR) study presented in this thesis forms part of an international collaborative effort to identify potent and selective inhibitors of an MRSA pyruvate kinase (PK) enzyme target. In earlier work the known marine natural product bromodeoxytopsentin (1.6), isolated from a South African marine sponge Topsentia pachastrelloides, exhibited selective and significant inhibition of MRSA PK (IC₅₀ 60 nM). Accordingly bromodeoxytopsentin provided the initial chemical scaffold around which our SAR study was developed. Following a comprehensive introduction, providing the necessary background to the research described in subsequent Chapters, this thesis has been divided into three major parts. Part one (Chapter 2) documents the synthesis of two natural imidazole containing topsentin analogues 1.40, 1.46, five new synthetic analogues 1.58—1.61, 2.104. In the process we developed a new method for the synthesis of topsentin derivatives via selenium dioxide mediated oxidation of N-Boc protected 3-acetylindoles to yield glyoxal intermediates which were subsequently cyclized and deprotected to yield the desired products. Interestingly we were able to demonstrate a delicate relationship between the relative equivalents of selenium dioxide and water used during the oxidation step, careful manipulation of which was required to prevent the uncontrolled formation of side products. Synthetic compounds 1.40, 1.46, 1.58—1.61 were found to be potent inhibitors of MRSA PK (IC₅₀ 238, 2.1, 23, 1.4, 6.3 and 3.2 nM respectively) with 1000-10000 fold selectivity for MRSA PK over four human orthologs. In the second part of this thesis (Chapter 3) we report the successful synthesis of a cohort of previously unknown thiazole containing bisindole topsentin analogues 1.62—1.68 via a Hantzsch thiazole synthesis. Bioassay results revealed that these compounds were only moderate inhibitors of MRSA PK (IC₅₀ 5.1—20 μM) which suggested that inhibitory activity was significantly reduced upon substitution of the central imidazole ring of topsentin type analogues with a thiazole type ring. In addition in Chapter 3 we describe unsuccessful attempts to regiospecifically synthesize oxazole and imidazole topsentin analogues through a similar Hantzsch method. As a consequence of our efforts in this regard we investigated three key reactions in depth, namely the synthesis of 2.2, 3.38, 3.40, 3.41 via α-bromination of 3-acetylindole and the synthesis of indolyl-3-carbonylnitriles 2.13, 3.45—3.47 and α-oxo-1H-indole-3-thioacetamides 3.48—3.51. The investigation of the latter led to the isolation and elucidation of two anomalous N,N-dimethyl-1H-indole-3-carboxamides 3.52 and 3.53. Finally the third part of this thesis (Chapter 4) deals with in silico assessment of the binding of both the imidazole and thiazole containing bisindole alkaloids to the MRSA PK protein which initially guided our SAR studies. In this chapter we reveal that there appears to be no correlation between in silico binding predictions and in vitro MRSA PK inhibitory bioassay data. Superficially it seems that binding energy as determined by the docking program used for these studies correlated with the size of the indole substituents and did not reflect IC₅₀ MRSA PK inhibitory data. Although this led us to computationally explore possible alternative binding sites no clear alternative has been identified.
- Full Text:
- Date Issued: 2014
Targeting and characterizing potentially high yield aquifers in the neotectonic zones in the Eastern Cape Province in South Africa
- Authors: Madi, Kakaba
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: vital:11530 , http://hdl.handle.net/10353/d1021270
- Description: The Eastern Cape Province has, besides the three known neotectonic belts (southern, eastern and northern) a fourth zone, which is inactive. This inactive zone is located almost in its central part north of the southern neotectonic zone, and south of the northern neotectonic belt. The three above mentioned neotectonic belts (southern, eastern and northern) were chosen for this study, each one with its own characteristics. This study aims at characterizing and targeting potentially high yield aquifers in the neotectonic zones in the Eastern Cape Province. The methods used in this study include: 1) A comprehensive literature review on neotectonics in South Africa in general and in the Eastern Cape Province in particular; 2) Extraction of lineaments through remote sensing and examination of digital elevation models; 3) Examination of seismic data for the subsurface visualization onshore and offshore; 4) Study on the genesis of the Grahamstown kaolin deposits through the structural component; and 5) Acquisition and interpretation of magnetic, electromagnetic and radiometric data from three of the hot springs in the northern neotectonic belt. The results indicate the following: 1) Old map of seismic epicentres in South Africa need to be reviewed continually. The Eastern Cape was regarded as quiescent in terms of seismicity. However, the investigation from recent seismic epicenters downloadable from the IRIS website has shown that recent seismic events occurred in the Eastern Cape Province especially in the northern and southern neotectonic belts. The central part located north of the southern neotectonic belt and south of the northern neotectonic belt is inactive. This inactive zone can be considered for the storage of nuclear wastes. 2) The eastern neotectonic belt has, like the northern neotectonic belt, a higher density of lineaments oriented northwest-southeast, which makes it the second important neotectonic belt. These lineaments correlate with the normalized difference vegetation index indicative of a good circulation of groundwater. In the south, the Eastern Cape great lineament oriented east-west is now considered a neotectonic domain because many seismic epicentres occur therein. Its geomorphologic shape in graben type form is a favourable structure for groundwater catchment. The surface topography is not uniform and high elevations in the east are related to the uplift that took place in the Quaternary. Most vector gradients are oriented east-west, a fact to be reckon with in the study of surface water flow and aquifers characterization. 3) Offshore along the east coast, the subsurface is affected by neotectonic faults, which are probably splays of the Agulhas Falkland Fractured Zone (AFFZ). The folds that occur are related to the regional compressional stress known as the Wegener Stress Anomaly (WSM). On land, straight lines from seismic profiles indicate that weathering occurs in consolidated materials probably along faults or fractures, unconsolidated sediments always have wavy profiles. On the other hand, field observations in King Williams Town have clearly shown that a tectonic uplift took place on a dolerite sill overlain by mudstones and sandstones. The uplift is possibly related to the Amatole-Swaziland event that occurred in the last five millions years. The escarpment along this dolerite sill overlain by sedimentary rocks is a meso-scale fault with a dip-slip component. Healthy vegetation and a river flowing parallel to the cliff indicate groundwater flow in the zone of weakness. 4) In the southern neotectonic belt there is a clear northwest-southeast horizontal compression and a southwest-northeast vertical to sub-vertical extension. Enrichment of granitic breccias and feldspar in the Grahamstown Dwyka tillite is the source for the formation of kaolin deposits. The weathering starts in the granitic breccias through their extensional fractures and then extends in the matrix, which has micro-fractures that are only visible with the transmitted microscope. Combined extensional strike-slip and dip-slip faulting is responsible for the earthquakes in the region of Grahamstown where the kaolin is formed. There is also an unreported thermal (quartz veins) and neotectonic event identified in this region. 5) The hot springs in the northern neotectonic belt are connected by a regional neotectonic fault. The use of magnetic and electromagnetic methods helped to decipher the occurrence of faults, fractures, dolerite dykes, and variable degree of weathering. Uranium/potassium ratios derived from radiometric surveys show that areas around some hot springs are characterized by enrichment in uranium. High concentrations of thorium are related to its low capacity of being easily dissolved in water. It can be concluded that seismicity, hot springs and accordingly deep groundwater circulation, high density of lineaments, quaternary tectonic uplift, are the predominate characteristics of the three neotectonic zones. Furthermore, on the environmental point of view, thorium concentration is higher than that of either uranium or potassium. Although it is nonetheless below the world average threshold of 7.4 ppm according to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), it may be a source of radiation hazard to humans and animals if they are subjected to prolonged exposure. All the neotectonic zones in the Eastern Cape Province present potentials to host good and important aquifers. It is suggested that the Eastern Cape great lineament in the southern neotectonic belt and the Kokstad-Koffiefontein seismic belt in the northern neotectonic belt, be monitored for future research regarding, neotectonics, seismic risk assessment and hydrogeology.
- Full Text:
- Date Issued: 2014
- Authors: Madi, Kakaba
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: vital:11530 , http://hdl.handle.net/10353/d1021270
- Description: The Eastern Cape Province has, besides the three known neotectonic belts (southern, eastern and northern) a fourth zone, which is inactive. This inactive zone is located almost in its central part north of the southern neotectonic zone, and south of the northern neotectonic belt. The three above mentioned neotectonic belts (southern, eastern and northern) were chosen for this study, each one with its own characteristics. This study aims at characterizing and targeting potentially high yield aquifers in the neotectonic zones in the Eastern Cape Province. The methods used in this study include: 1) A comprehensive literature review on neotectonics in South Africa in general and in the Eastern Cape Province in particular; 2) Extraction of lineaments through remote sensing and examination of digital elevation models; 3) Examination of seismic data for the subsurface visualization onshore and offshore; 4) Study on the genesis of the Grahamstown kaolin deposits through the structural component; and 5) Acquisition and interpretation of magnetic, electromagnetic and radiometric data from three of the hot springs in the northern neotectonic belt. The results indicate the following: 1) Old map of seismic epicentres in South Africa need to be reviewed continually. The Eastern Cape was regarded as quiescent in terms of seismicity. However, the investigation from recent seismic epicenters downloadable from the IRIS website has shown that recent seismic events occurred in the Eastern Cape Province especially in the northern and southern neotectonic belts. The central part located north of the southern neotectonic belt and south of the northern neotectonic belt is inactive. This inactive zone can be considered for the storage of nuclear wastes. 2) The eastern neotectonic belt has, like the northern neotectonic belt, a higher density of lineaments oriented northwest-southeast, which makes it the second important neotectonic belt. These lineaments correlate with the normalized difference vegetation index indicative of a good circulation of groundwater. In the south, the Eastern Cape great lineament oriented east-west is now considered a neotectonic domain because many seismic epicentres occur therein. Its geomorphologic shape in graben type form is a favourable structure for groundwater catchment. The surface topography is not uniform and high elevations in the east are related to the uplift that took place in the Quaternary. Most vector gradients are oriented east-west, a fact to be reckon with in the study of surface water flow and aquifers characterization. 3) Offshore along the east coast, the subsurface is affected by neotectonic faults, which are probably splays of the Agulhas Falkland Fractured Zone (AFFZ). The folds that occur are related to the regional compressional stress known as the Wegener Stress Anomaly (WSM). On land, straight lines from seismic profiles indicate that weathering occurs in consolidated materials probably along faults or fractures, unconsolidated sediments always have wavy profiles. On the other hand, field observations in King Williams Town have clearly shown that a tectonic uplift took place on a dolerite sill overlain by mudstones and sandstones. The uplift is possibly related to the Amatole-Swaziland event that occurred in the last five millions years. The escarpment along this dolerite sill overlain by sedimentary rocks is a meso-scale fault with a dip-slip component. Healthy vegetation and a river flowing parallel to the cliff indicate groundwater flow in the zone of weakness. 4) In the southern neotectonic belt there is a clear northwest-southeast horizontal compression and a southwest-northeast vertical to sub-vertical extension. Enrichment of granitic breccias and feldspar in the Grahamstown Dwyka tillite is the source for the formation of kaolin deposits. The weathering starts in the granitic breccias through their extensional fractures and then extends in the matrix, which has micro-fractures that are only visible with the transmitted microscope. Combined extensional strike-slip and dip-slip faulting is responsible for the earthquakes in the region of Grahamstown where the kaolin is formed. There is also an unreported thermal (quartz veins) and neotectonic event identified in this region. 5) The hot springs in the northern neotectonic belt are connected by a regional neotectonic fault. The use of magnetic and electromagnetic methods helped to decipher the occurrence of faults, fractures, dolerite dykes, and variable degree of weathering. Uranium/potassium ratios derived from radiometric surveys show that areas around some hot springs are characterized by enrichment in uranium. High concentrations of thorium are related to its low capacity of being easily dissolved in water. It can be concluded that seismicity, hot springs and accordingly deep groundwater circulation, high density of lineaments, quaternary tectonic uplift, are the predominate characteristics of the three neotectonic zones. Furthermore, on the environmental point of view, thorium concentration is higher than that of either uranium or potassium. Although it is nonetheless below the world average threshold of 7.4 ppm according to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), it may be a source of radiation hazard to humans and animals if they are subjected to prolonged exposure. All the neotectonic zones in the Eastern Cape Province present potentials to host good and important aquifers. It is suggested that the Eastern Cape great lineament in the southern neotectonic belt and the Kokstad-Koffiefontein seismic belt in the northern neotectonic belt, be monitored for future research regarding, neotectonics, seismic risk assessment and hydrogeology.
- Full Text:
- Date Issued: 2014
Teachers’ experiences of change : a case study analysis of a school-based intervention in rural Kwazulu-Natal
- Authors: James, Sally Jane
- Date: 2014
- Subjects: David Rattray Foundation , Educational change -- South Africa -- KwaZulu-Natal -- Case studies , Rural schools -- South Africa -- KwaZulu-Natal , Teachers -- Training of -- South Africa -- KwaZulu-Natal , Community and school -- South Africa -- KwaZulu-Natal , KwaZulu-Natal (South Africa) -- Social conditions , KwaZulu-Natal (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1980 , http://hdl.handle.net/10962/d1013118
- Description: The research presented in this thesis is a case study analysis of the school-based intervention initiated by the David Rattray Foundation [DRF]. David Rattray, a South African historian well known for his contribution to the 1879-1896 Anglo-Zulu War heritage, was murdered in January 2007. In response to his untimely death, the DRF was established by family and friends with the hope of improving education within the Umzinyathi rural municipal district of KwaZulu-Natal. This study consisted of three phases: Phase I (May-December 2011); Phase II (January-December 2012), and Phase III (December 2012-October 2013). During Phase I, the focus was on describing the broader context in which the case is located. It resulted in a narrative account of the emergence of the DRF as a non-governmental organisation [NGO] working towards change within the local rural school community. During Phase II the focus shifted from the broader socio-political and economic context to the human dimension which included teachers, principals, volunteer workers and a district official working in the schools. During Phase II the approach to change adopted by the DRF was critically analysed in relation to models of change described in the literature. Teachers’ experiences of change were also examined. Phase III was a synthesis of the findings from the first two research phases. By drawing on systems and complexity theory perspectives, insights were gained enabling a deep understanding of the DRF’s school-based intervention as a whole. This research is a qualitative study that seeks to understand individual teachers’ experiences and participation in a process of change that reaches beyond the individual and his/her immediate context. The adoption of a realist ontology (Maxwell, 2012) and application of an explanatory heuristic based on the critical realist philosophy of Bhaskar (1979, 1980, 2011) enabled the layered analysis and in-depth interpretation that characterises the study. The findings of the study reveal a complex and ongoing process of change within a rural school context. The results illuminate the efficacy of a collaborative partnership between civil society (the DRF), the local community, under the leadership of a tribal authority, and the local government (KwaZulu-Natal Provincial Department of Education). It also reveals how teachers within this particular context do not have a strong voice in the change process and hence participate only superficially in the school-based intervention. It is probable that the constraining mechanisms revealed through this research are not exclusive to this particular case study, but are common across the South African rural school context. The main contention of this thesis is that these mechanisms need further interrogation in order to enable further change and permit the active participation of teachers in the process.While the study illuminates many of the tensions and problems faced by the schools and the community in which they are located, it also highlights the achievements and selfless attitude of many people working towards change and improvement within the schools. This case study thus provides an example to all South Africans of what can be achieved with commitment and effort.
- Full Text:
- Date Issued: 2014
- Authors: James, Sally Jane
- Date: 2014
- Subjects: David Rattray Foundation , Educational change -- South Africa -- KwaZulu-Natal -- Case studies , Rural schools -- South Africa -- KwaZulu-Natal , Teachers -- Training of -- South Africa -- KwaZulu-Natal , Community and school -- South Africa -- KwaZulu-Natal , KwaZulu-Natal (South Africa) -- Social conditions , KwaZulu-Natal (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1980 , http://hdl.handle.net/10962/d1013118
- Description: The research presented in this thesis is a case study analysis of the school-based intervention initiated by the David Rattray Foundation [DRF]. David Rattray, a South African historian well known for his contribution to the 1879-1896 Anglo-Zulu War heritage, was murdered in January 2007. In response to his untimely death, the DRF was established by family and friends with the hope of improving education within the Umzinyathi rural municipal district of KwaZulu-Natal. This study consisted of three phases: Phase I (May-December 2011); Phase II (January-December 2012), and Phase III (December 2012-October 2013). During Phase I, the focus was on describing the broader context in which the case is located. It resulted in a narrative account of the emergence of the DRF as a non-governmental organisation [NGO] working towards change within the local rural school community. During Phase II the focus shifted from the broader socio-political and economic context to the human dimension which included teachers, principals, volunteer workers and a district official working in the schools. During Phase II the approach to change adopted by the DRF was critically analysed in relation to models of change described in the literature. Teachers’ experiences of change were also examined. Phase III was a synthesis of the findings from the first two research phases. By drawing on systems and complexity theory perspectives, insights were gained enabling a deep understanding of the DRF’s school-based intervention as a whole. This research is a qualitative study that seeks to understand individual teachers’ experiences and participation in a process of change that reaches beyond the individual and his/her immediate context. The adoption of a realist ontology (Maxwell, 2012) and application of an explanatory heuristic based on the critical realist philosophy of Bhaskar (1979, 1980, 2011) enabled the layered analysis and in-depth interpretation that characterises the study. The findings of the study reveal a complex and ongoing process of change within a rural school context. The results illuminate the efficacy of a collaborative partnership between civil society (the DRF), the local community, under the leadership of a tribal authority, and the local government (KwaZulu-Natal Provincial Department of Education). It also reveals how teachers within this particular context do not have a strong voice in the change process and hence participate only superficially in the school-based intervention. It is probable that the constraining mechanisms revealed through this research are not exclusive to this particular case study, but are common across the South African rural school context. The main contention of this thesis is that these mechanisms need further interrogation in order to enable further change and permit the active participation of teachers in the process.While the study illuminates many of the tensions and problems faced by the schools and the community in which they are located, it also highlights the achievements and selfless attitude of many people working towards change and improvement within the schools. This case study thus provides an example to all South Africans of what can be achieved with commitment and effort.
- Full Text:
- Date Issued: 2014
The changing image of women in Francis Imbuga's Oeuvre
- Oketch, Selline Atieno, West, Mary Eileen
- Authors: Oketch, Selline Atieno , West, Mary Eileen
- Date: 2014
- Subjects: Women in literature , Feminist criticism -- Kenya
- Language: English
- Type: Thesis , Doctoral , DLitt
- Identifier: http://hdl.handle.net/10948/2949 , vital:20373
- Description: The aim of this study was to examine the changing image of women in the oeuvre of Francis Imbuga. Focusing on seven stage plays and two novels published between 1976 and 2011, the study examines the depiction of female characters within the social, cultural and political contexts of post-independence African societies. The depiction of female characters in literature has attracted the attention of numerous scholars globally, particularly with regards to negative female stereotypes in male authored works. This study explores Imbuga’s attitude towards female stereotypes and gender inequalities in literary texts. Using an eclectic framework that includes feminist criticism, feminist stylistics, gender theory and the formal strategies of literature, the study examined gender relations in these texts through the analysis of language and discourse of characters. Further, the study uses the interpretive methods of textual analysis to categorize these works into three phases based on their portrayal of female characters. This method reveals a systematic transformation in the characterization of women from disadvantaged positions in the patriarchal society to more prominent positions in the contemporary society. The study demonstrates that Imbuga makes a positive response to feminism and devices a unique perspective on feminism that celebrates both the domestic and public roles of female characters. In this sense, the female characters contribute to the moral content and aesthetic values of Imbuga’s works. The study concludes that Imbuga views the transformation of female characters in literary texts as part of the broader social change that is desirable in the society. Ultimately, this vision involves shifting focus from the preoccupation with gender inequalities to concern for the welfare and dignity of the human person. Based on the conclusions, recommendations for further study include investigation into the educative and social role of the performing arts as a means of raising consciousness on issues such as HIV/Aids, use of indigenous knowledge in solving contemporary issues, incorporation of African morality and traditions in contemporary literature and a comparative study of Imbuga’s feministic vision with that of other writers.
- Full Text:
- Date Issued: 2014
- Authors: Oketch, Selline Atieno , West, Mary Eileen
- Date: 2014
- Subjects: Women in literature , Feminist criticism -- Kenya
- Language: English
- Type: Thesis , Doctoral , DLitt
- Identifier: http://hdl.handle.net/10948/2949 , vital:20373
- Description: The aim of this study was to examine the changing image of women in the oeuvre of Francis Imbuga. Focusing on seven stage plays and two novels published between 1976 and 2011, the study examines the depiction of female characters within the social, cultural and political contexts of post-independence African societies. The depiction of female characters in literature has attracted the attention of numerous scholars globally, particularly with regards to negative female stereotypes in male authored works. This study explores Imbuga’s attitude towards female stereotypes and gender inequalities in literary texts. Using an eclectic framework that includes feminist criticism, feminist stylistics, gender theory and the formal strategies of literature, the study examined gender relations in these texts through the analysis of language and discourse of characters. Further, the study uses the interpretive methods of textual analysis to categorize these works into three phases based on their portrayal of female characters. This method reveals a systematic transformation in the characterization of women from disadvantaged positions in the patriarchal society to more prominent positions in the contemporary society. The study demonstrates that Imbuga makes a positive response to feminism and devices a unique perspective on feminism that celebrates both the domestic and public roles of female characters. In this sense, the female characters contribute to the moral content and aesthetic values of Imbuga’s works. The study concludes that Imbuga views the transformation of female characters in literary texts as part of the broader social change that is desirable in the society. Ultimately, this vision involves shifting focus from the preoccupation with gender inequalities to concern for the welfare and dignity of the human person. Based on the conclusions, recommendations for further study include investigation into the educative and social role of the performing arts as a means of raising consciousness on issues such as HIV/Aids, use of indigenous knowledge in solving contemporary issues, incorporation of African morality and traditions in contemporary literature and a comparative study of Imbuga’s feministic vision with that of other writers.
- Full Text:
- Date Issued: 2014
The characterization of DNAJC3: elucidating the function of the TPR domains
- Mutsvunguma, Lorraine Zvichapera
- Authors: Mutsvunguma, Lorraine Zvichapera
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55874 , vital:26751
- Description: DNAJC3 is a novel member of the DNAJ family with two domains linked to co-chaperone functions, namely the tetratricopeptide repeat (TPR) and J domain. Out of the two domains, the TPR domains are the least characterized. Therefore, the aim of this study was to characterize and elucidate additional functions of DNAJC3 TPR domains through in silico, in vitro and ex vivo approaches. Through multiple sequence and structural alignment as well as electrostatic potential analysis, DNAJC3 TPR domain were found to be most similar to TPR-containing proteins with Hsp90 or Hsp70 independent functions. In vitro pull down assays illustrated that DNAJC3 TPR domains did not interact with either cytosolic Hsp90 and Hsp70 or Grp78 and Grp94 directly, however a potential indirect interaction with Grp94 and Hsp90 was observed in mammalian lysates, via pull down assays; suggesting the formation of a complex between the proteins mediated by a specific substrate. DNAJC3 TPR domains were found to bind indiscriminately to both native and heat denatured substrates in a dose dependent manner. DNAJC3 TPR domains bound to β-galactosidase with greater affinity than malate dehydrogenase (MDH), suggesting that DNAJC3 TPR domains might exhibit substrate specificity that has not been reported before. Preliminary ex vivo analysis of DNAJC3 in mammalian cells showed that induced stress conditions did not alter the cytosolic or endoplasmic reticulum (ER) localization, or levels of DNAJC3 protein, suggesting that the protein is not stress inducible. However, protein levels of DNAJC3 were dramatically reduced by Hsp90 inhibitor novobiocin at 500 μM. Transient knockdown DNAJC3 did not change the protein levels of either Grp78 or Grp94, but decreased the protein levels of Hsp70/Hsp90 organizing protein HOP. On the other hand, protein levels of DNAJC3 were increased in HOP depleted cells. In conclusion, this study was the first to experimentally demonstrate that DNAJC3 TPR domains do not interact directly with Hsp90, Hsp70, Grp78 or Grp94, and therefore DNAJC3 is unlikely to participate in traditional co-chaperone interactions with those proteins via its TPR domain. However, the J domain is known to interact with Grp78. The discovery that DNAJC3 TPR domains resemble that of TPR-containing proteins with functions independent of Hsp90 or Hsp70 suggests that DNAJC3 might link the Hsp70/Grp78 chaperone machinery to non co-chaperone related functions, which requires further analysis.
- Full Text:
- Date Issued: 2014
- Authors: Mutsvunguma, Lorraine Zvichapera
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55874 , vital:26751
- Description: DNAJC3 is a novel member of the DNAJ family with two domains linked to co-chaperone functions, namely the tetratricopeptide repeat (TPR) and J domain. Out of the two domains, the TPR domains are the least characterized. Therefore, the aim of this study was to characterize and elucidate additional functions of DNAJC3 TPR domains through in silico, in vitro and ex vivo approaches. Through multiple sequence and structural alignment as well as electrostatic potential analysis, DNAJC3 TPR domain were found to be most similar to TPR-containing proteins with Hsp90 or Hsp70 independent functions. In vitro pull down assays illustrated that DNAJC3 TPR domains did not interact with either cytosolic Hsp90 and Hsp70 or Grp78 and Grp94 directly, however a potential indirect interaction with Grp94 and Hsp90 was observed in mammalian lysates, via pull down assays; suggesting the formation of a complex between the proteins mediated by a specific substrate. DNAJC3 TPR domains were found to bind indiscriminately to both native and heat denatured substrates in a dose dependent manner. DNAJC3 TPR domains bound to β-galactosidase with greater affinity than malate dehydrogenase (MDH), suggesting that DNAJC3 TPR domains might exhibit substrate specificity that has not been reported before. Preliminary ex vivo analysis of DNAJC3 in mammalian cells showed that induced stress conditions did not alter the cytosolic or endoplasmic reticulum (ER) localization, or levels of DNAJC3 protein, suggesting that the protein is not stress inducible. However, protein levels of DNAJC3 were dramatically reduced by Hsp90 inhibitor novobiocin at 500 μM. Transient knockdown DNAJC3 did not change the protein levels of either Grp78 or Grp94, but decreased the protein levels of Hsp70/Hsp90 organizing protein HOP. On the other hand, protein levels of DNAJC3 were increased in HOP depleted cells. In conclusion, this study was the first to experimentally demonstrate that DNAJC3 TPR domains do not interact directly with Hsp90, Hsp70, Grp78 or Grp94, and therefore DNAJC3 is unlikely to participate in traditional co-chaperone interactions with those proteins via its TPR domain. However, the J domain is known to interact with Grp78. The discovery that DNAJC3 TPR domains resemble that of TPR-containing proteins with functions independent of Hsp90 or Hsp70 suggests that DNAJC3 might link the Hsp70/Grp78 chaperone machinery to non co-chaperone related functions, which requires further analysis.
- Full Text:
- Date Issued: 2014
The consolidation of forecests with regression models
- Venter, Daniel Jacobus Lodewyk
- Authors: Venter, Daniel Jacobus Lodewyk
- Date: 2014
- Subjects: Regression analysis -- Mathematical models , Forecasting -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10582 , http://hdl.handle.net/10948/d1020964
- Description: The primary objective of this study was to develop a dashboard for the consolidation of multiple forecasts utilising a range of multiple linear regression models. The term dashboard is used to describe with a single word the characteristics of the forecasts consolidation application that was developed to provide the required functionalities via a graphical user interface structured as a series of interlinked screens. Microsoft Excel© was used as the platform to develop the dashboard named ConFoRM (acronym for Consolidate Forecasts with Regression Models). The major steps of the consolidation process incorporated in ConFoRM are: 1. Input historical data. Select appropriate analysis and holdout samples. 3. Specify regression models to be considered as candidates for the final model to be used for the consolidation of forecasts. 4. Perform regression analysis and holdout analysis for each of the models specified in step 3. 5. Perform post-holdout testing to assess the performance of the model with best holdout validation results on out-of-sample data. 6. Consolidate forecasts. Two data transformations are available: the removal of growth and time-periods effect from the time series; a translation of the time series by subtracting ̅i, the mean of all the forecasts for data record i, from the variable being predicted and its related forecasts for each data record I. The pre-defined regression models available for ordinary least square linear regression models (LRM) are: a. A set of k simple LRM’s, one for each of the k forecasts; b. A multiple LRM that includes all the forecasts: c. A multiple LRM that includes all the forecasts and as many of the first-order interactions between the input forecasts as allowed by the sample size and the maximum number of predictors provided by the dashboard with the interactions included in the model to be those with the highest individual correlation with the variable being predicted; d. A multiple LRM that includes as many of the forecasts and first-order interactions between the input forecasts as allowed by the sample size and the maximum number of predictors provided by the dashboard: with the forecasts and interactions included in the model to be those with the highest individual correlation with the variable being predicted; e. A simple LRM with the predictor variable being the mean of the forecasts: f. A set of simple LRM’s with the predictor variable in each case being the weighted mean of the forecasts with different formulas for the weights Also available is an ad hoc user specified model in terms of the forecasts and the predictor variables generated by the dashboard for the pre-defined models. Provision is made in the regression analysis for both of forward entry and backward removal regression. Weighted least squares (WLS) regression can be performed optionally based on the age of forecasts with smaller weight for older forecasts.
- Full Text:
- Date Issued: 2014
- Authors: Venter, Daniel Jacobus Lodewyk
- Date: 2014
- Subjects: Regression analysis -- Mathematical models , Forecasting -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10582 , http://hdl.handle.net/10948/d1020964
- Description: The primary objective of this study was to develop a dashboard for the consolidation of multiple forecasts utilising a range of multiple linear regression models. The term dashboard is used to describe with a single word the characteristics of the forecasts consolidation application that was developed to provide the required functionalities via a graphical user interface structured as a series of interlinked screens. Microsoft Excel© was used as the platform to develop the dashboard named ConFoRM (acronym for Consolidate Forecasts with Regression Models). The major steps of the consolidation process incorporated in ConFoRM are: 1. Input historical data. Select appropriate analysis and holdout samples. 3. Specify regression models to be considered as candidates for the final model to be used for the consolidation of forecasts. 4. Perform regression analysis and holdout analysis for each of the models specified in step 3. 5. Perform post-holdout testing to assess the performance of the model with best holdout validation results on out-of-sample data. 6. Consolidate forecasts. Two data transformations are available: the removal of growth and time-periods effect from the time series; a translation of the time series by subtracting ̅i, the mean of all the forecasts for data record i, from the variable being predicted and its related forecasts for each data record I. The pre-defined regression models available for ordinary least square linear regression models (LRM) are: a. A set of k simple LRM’s, one for each of the k forecasts; b. A multiple LRM that includes all the forecasts: c. A multiple LRM that includes all the forecasts and as many of the first-order interactions between the input forecasts as allowed by the sample size and the maximum number of predictors provided by the dashboard with the interactions included in the model to be those with the highest individual correlation with the variable being predicted; d. A multiple LRM that includes as many of the forecasts and first-order interactions between the input forecasts as allowed by the sample size and the maximum number of predictors provided by the dashboard: with the forecasts and interactions included in the model to be those with the highest individual correlation with the variable being predicted; e. A simple LRM with the predictor variable being the mean of the forecasts: f. A set of simple LRM’s with the predictor variable in each case being the weighted mean of the forecasts with different formulas for the weights Also available is an ad hoc user specified model in terms of the forecasts and the predictor variables generated by the dashboard for the pre-defined models. Provision is made in the regression analysis for both of forward entry and backward removal regression. Weighted least squares (WLS) regression can be performed optionally based on the age of forecasts with smaller weight for older forecasts.
- Full Text:
- Date Issued: 2014
The design of quantum dots and their conjugates as luminescent probes for analyte sensing
- Authors: Adegoke, Oluwasesan
- Date: 2014
- Subjects: Quantum dots Anolytes Luminescent probes Luminescence spectroscopy Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4457 , http://hdl.handle.net/10962/d1010866
- Description: The design and applications of quantum dots (QDs) as fluorescent probes for analyte sensing is presented. Cadmium based thiol-capped QDs were employed as probe for the detection of analytes. Comparative studies between core CdTe and core-shell CdTe@ZnS QDs showed that the overall sensitivity and selectivity of the sensor was dependent on the nature of the capping agent and the QDs employed, hence making CdTe@ZnS QDs a more superior sensor than the core. To explore the luminescent sensing of QDs based on the fluorescence “turn ON” mode, L-glutathione-capped CdTe QDs was conjugated to 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT) to form a QDs-4AT conjugate system. The QDs-4AT nanoprobe was highly selective and sensitive to the detection of bromide ion with a very low limit of detection. Subsequently, metallo-phthalocyanines (MPcs) were employed as host molecules on the surface of QDs based on the covalent linking of the QDs to the MPc. Elucidation of the reaction mechanism showed that the fluorescence “turn ON” effect of the QDs-MPc probe in the presence of the analyte was due to axial ligation of the analytes to the Pc ring. Studies showed that the type of substituent attached to the MPc ring influenced the overall sensitivity of the probe. Additionally, a comparative investigation using newly synthesized phthalocyanine and triaza-benzcorrole complexes was conducted when these complexes were conjugated to CdSe@ZnS QDs for analyte sensing. Results showed that the triaza-benzcorrole complex can be employed as a host-molecule sensor but displayed a lower sensitivity for analyte sensing in comparison to the phthalocyanine complex.
- Full Text:
- Date Issued: 2014
- Authors: Adegoke, Oluwasesan
- Date: 2014
- Subjects: Quantum dots Anolytes Luminescent probes Luminescence spectroscopy Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4457 , http://hdl.handle.net/10962/d1010866
- Description: The design and applications of quantum dots (QDs) as fluorescent probes for analyte sensing is presented. Cadmium based thiol-capped QDs were employed as probe for the detection of analytes. Comparative studies between core CdTe and core-shell CdTe@ZnS QDs showed that the overall sensitivity and selectivity of the sensor was dependent on the nature of the capping agent and the QDs employed, hence making CdTe@ZnS QDs a more superior sensor than the core. To explore the luminescent sensing of QDs based on the fluorescence “turn ON” mode, L-glutathione-capped CdTe QDs was conjugated to 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT) to form a QDs-4AT conjugate system. The QDs-4AT nanoprobe was highly selective and sensitive to the detection of bromide ion with a very low limit of detection. Subsequently, metallo-phthalocyanines (MPcs) were employed as host molecules on the surface of QDs based on the covalent linking of the QDs to the MPc. Elucidation of the reaction mechanism showed that the fluorescence “turn ON” effect of the QDs-MPc probe in the presence of the analyte was due to axial ligation of the analytes to the Pc ring. Studies showed that the type of substituent attached to the MPc ring influenced the overall sensitivity of the probe. Additionally, a comparative investigation using newly synthesized phthalocyanine and triaza-benzcorrole complexes was conducted when these complexes were conjugated to CdSe@ZnS QDs for analyte sensing. Results showed that the triaza-benzcorrole complex can be employed as a host-molecule sensor but displayed a lower sensitivity for analyte sensing in comparison to the phthalocyanine complex.
- Full Text:
- Date Issued: 2014
The development of a financing model for agricultural production in South Africa
- Authors: Oberholster, Jacobus Hoon
- Date: 2014
- Subjects: Agriculture -- South Africa -- Finance , Agricultural productivity -- South Africa , Agricultural industries -- South Africa
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/3041 , vital:20389
- Description: The world agricultural industry, despite numerous supply and demand challenges, has to significantly increase its production capacity to satisfy the increased demand for food and successfully address the issues surrounding food security. Access to credit is however a key enabler in this regard, while a lack of it limits the adaptive capacity of agricultural producers. The financing needs of agricultural producers however vary and are influenced by the different production systems which have different investment, revenue and risk patterns. The sector is unique in that the risk and uncertainty in agriculture are increased by the nature of agricultural production systems, which is in many cases driven by unpredictable external factors such as adverse weather conditions. In addition agricultural production systems also function within the total food system which consists of a number of interrelated subsystems, each presenting agricultural producers with a unique set of risk factors that need to be taken into account. The development of new and innovative financing solutions for the sector therefore requires a thorough understanding of the multidimensional nature of agriculture and the unique characteristics of the sector. The purpose of this study was to contribute to the development of new and innovative financing solutions for the agricultural sector in South Africa.
- Full Text:
- Date Issued: 2014
- Authors: Oberholster, Jacobus Hoon
- Date: 2014
- Subjects: Agriculture -- South Africa -- Finance , Agricultural productivity -- South Africa , Agricultural industries -- South Africa
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/3041 , vital:20389
- Description: The world agricultural industry, despite numerous supply and demand challenges, has to significantly increase its production capacity to satisfy the increased demand for food and successfully address the issues surrounding food security. Access to credit is however a key enabler in this regard, while a lack of it limits the adaptive capacity of agricultural producers. The financing needs of agricultural producers however vary and are influenced by the different production systems which have different investment, revenue and risk patterns. The sector is unique in that the risk and uncertainty in agriculture are increased by the nature of agricultural production systems, which is in many cases driven by unpredictable external factors such as adverse weather conditions. In addition agricultural production systems also function within the total food system which consists of a number of interrelated subsystems, each presenting agricultural producers with a unique set of risk factors that need to be taken into account. The development of new and innovative financing solutions for the sector therefore requires a thorough understanding of the multidimensional nature of agriculture and the unique characteristics of the sector. The purpose of this study was to contribute to the development of new and innovative financing solutions for the agricultural sector in South Africa.
- Full Text:
- Date Issued: 2014