The investigation of type-specific features of the copper coordinating AA9 proteins and their effect on the interaction with crystalline cellulose using molecular dynamics studies
- Authors: Moses, Vuyani
- Date: 2018
- Subjects: Copper proteins , Cellulose , Molecular dynamics , Cellulose -- Biodegradation , Bioinformatics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58327 , vital:27230
- Description: AA9 proteins are metallo-enzymes which are crucial for the early stages of cellulose degradation. AA9 proteins have been suggested to cleave glycosidic bonds linking cellulose through the use of their Cu2+ coordinating active site. AA9 proteins possess different regioselectivities depending on the resulting cleavage they form and as result, are grouped accordingly. Type 1 AA9 proteins cleave the C1 carbon of cellulose while Type 2 AA9 proteins cleave the C4 carbon and Type 3 AA9 proteins cleave either C1 or C4 carbons. The steric congestion of the AA9 active site has been proposed to be a contributor to the observed regioselectivity. As such, a bioinformatics characterisation of type-specific sequence and structural features was performed. Initially AA9 protein sequences were obtained from the Pfam database and multiple sequence alignment was performed. The sequences were phylogenetically characterised and sequences were grouped into their respective types and sub-groups were identified. A selection analysis was performed on AA9 LPMO types to determine the selective pressure acting on AA9 protein residues. Motif discovery was then performed to identify conserved sequence motifs in AA9 proteins. Once type-specific sequence features were identified structural mapping was performed to assess possible effects on substrate interaction. Physicochemical property analysis was also performed to assess biochemical differences between AA9 LPMO types. Molecular dynamics (MD) simulations were then employed to dynamically assess the consequences of the discovered type-specific features on AA9-cellulose interaction. Due to the absence of AA9 specific force field parameters MD simulations were not readily applicable. As a result, Potential Energy Surface (PES) scans were performed to evaluate the force field parameters for the AA9 active site using the PM6 semi empirical approach and least squares fitting. A Type 1 AA9 active site was constructed from the crystal structure 4B5Q, encompassing only the Cu2+ coordinating residues, the Cu2+ ion and two water residues. Due to the similarity in AA9 active sites, the Type force field parameters were validated on all three AA9 LPMO types. Two MD simulations for each AA9 LPMO types were conducted using two separate Lennard-Jones parameter sets. Once completed, the MD trajectories were analysed for various features including the RMSD, RMSF, radius of gyration, coordination during simulation, hydrogen bonding, secondary structure conservation and overall protein movement. Force field parameters were successfully evaluated and validated for AA9 proteins. MD simulations of AA9 proteins were able to reveal the presence of unique type-specific binding modes of AA9 active sites to cellulose. These binding modes were characterised by the presence of unique type-specific loops which were present in Type 2 and 3 AA9 proteins but not in Type 1 AA9 proteins. The loops were found to result in steric congestion that affects how the Cu2+ ion interacts with cellulose. As a result, Cu2+ binding to cellulose was observed for Type 1 and not Type 2 and 3 AA9 proteins. In this study force field parameters have been evaluated for the Type 1 active site of AA9 proteins and this parameters were evaluated on all three types and binding. Future work will focus on identifying the nature of the reactive oxygen species and performing QM/MM calculations to elucidate the reactive mechanism of all three AA9 LPMO types.
- Full Text:
- Date Issued: 2018
- Authors: Moses, Vuyani
- Date: 2018
- Subjects: Copper proteins , Cellulose , Molecular dynamics , Cellulose -- Biodegradation , Bioinformatics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58327 , vital:27230
- Description: AA9 proteins are metallo-enzymes which are crucial for the early stages of cellulose degradation. AA9 proteins have been suggested to cleave glycosidic bonds linking cellulose through the use of their Cu2+ coordinating active site. AA9 proteins possess different regioselectivities depending on the resulting cleavage they form and as result, are grouped accordingly. Type 1 AA9 proteins cleave the C1 carbon of cellulose while Type 2 AA9 proteins cleave the C4 carbon and Type 3 AA9 proteins cleave either C1 or C4 carbons. The steric congestion of the AA9 active site has been proposed to be a contributor to the observed regioselectivity. As such, a bioinformatics characterisation of type-specific sequence and structural features was performed. Initially AA9 protein sequences were obtained from the Pfam database and multiple sequence alignment was performed. The sequences were phylogenetically characterised and sequences were grouped into their respective types and sub-groups were identified. A selection analysis was performed on AA9 LPMO types to determine the selective pressure acting on AA9 protein residues. Motif discovery was then performed to identify conserved sequence motifs in AA9 proteins. Once type-specific sequence features were identified structural mapping was performed to assess possible effects on substrate interaction. Physicochemical property analysis was also performed to assess biochemical differences between AA9 LPMO types. Molecular dynamics (MD) simulations were then employed to dynamically assess the consequences of the discovered type-specific features on AA9-cellulose interaction. Due to the absence of AA9 specific force field parameters MD simulations were not readily applicable. As a result, Potential Energy Surface (PES) scans were performed to evaluate the force field parameters for the AA9 active site using the PM6 semi empirical approach and least squares fitting. A Type 1 AA9 active site was constructed from the crystal structure 4B5Q, encompassing only the Cu2+ coordinating residues, the Cu2+ ion and two water residues. Due to the similarity in AA9 active sites, the Type force field parameters were validated on all three AA9 LPMO types. Two MD simulations for each AA9 LPMO types were conducted using two separate Lennard-Jones parameter sets. Once completed, the MD trajectories were analysed for various features including the RMSD, RMSF, radius of gyration, coordination during simulation, hydrogen bonding, secondary structure conservation and overall protein movement. Force field parameters were successfully evaluated and validated for AA9 proteins. MD simulations of AA9 proteins were able to reveal the presence of unique type-specific binding modes of AA9 active sites to cellulose. These binding modes were characterised by the presence of unique type-specific loops which were present in Type 2 and 3 AA9 proteins but not in Type 1 AA9 proteins. The loops were found to result in steric congestion that affects how the Cu2+ ion interacts with cellulose. As a result, Cu2+ binding to cellulose was observed for Type 1 and not Type 2 and 3 AA9 proteins. In this study force field parameters have been evaluated for the Type 1 active site of AA9 proteins and this parameters were evaluated on all three types and binding. Future work will focus on identifying the nature of the reactive oxygen species and performing QM/MM calculations to elucidate the reactive mechanism of all three AA9 LPMO types.
- Full Text:
- Date Issued: 2018
A critique of language policy and implementation strategies used in selected institutions of higher learning in South Africa
- Authors: Somlata, Zakhile
- Date: 2018
- Subjects: Language policy South Africa , Translanguaging (Linguistics) , Language and education South Africa , Language and languages Study and teaching South Africa , Education, Higher South Africa , Multilingualism South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62571 , vital:28208
- Description: This thesis evaluated the language policy implementation strategies used in selected universities of South Africa. The Constitution of the Republic of South African (1996) recognises eleven official languages, namely: English, Afrikaans, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, SiSwati, Sepedi, Tshivenda and Xitsonga. These official languages should enjoy the parity of esteem in all domains. The language practices are very important in the education of students at all levels of education but this study focuses on the language policy implementation in universities. Most universities of South Africa have their language policies but the dilemma is on the implementation of those language policies. The overarching aim of this study is to evaluate how university use language policy for access and success of the students and to assess the language policy implementation strategies, monitoring and evaluation. The language is central to the success of the students and this study further investigated to what extent are the universities use the linguistic repertoires of the students in their education. This study is rooted in orientations of language planning: Language as problem, language as right and language as resource (Ruiz, 1984). This thesis employed a mixed methods approach (qualitative and quantitative method) with convergent parallel design. The data was collected from eleven universities of South Africa and the participants in each university were the "Key informants" (experts and insiders) which comprised of member of Executive Management, a member of the Institutional Language Committee and a language lecturer; and a cohort of forty third year students. The Key informants participated in the qualitative data collection through the structured interviews. The forty third year students participated in the quantitative data collected through survey questionnaires. The language policy documents of the universities were also sampled to get a better understanding of the real language practices and the language policy. The thematic analysis was used to analyse transcripts that were developed from the interviews, data from the students was analysed through descriptive and inferential analyses with Statistical Package for the Social Sciences (SPSS) as a statistical test and document analysis was used to analyse the language policies; The findings show that universities have commitment to access of the students to institutions of Higher Education. The success of the students is being thwarted by the monolingual approach where most of the universities use English only as the medium of instruction. The monolingual approach negatively affects the academic success and excellent academic performance of the majority of students. The findings show that there is high demand from the students that the course materials should be provided in African languages. All selected universities have their language policy which is something positive but most of them are outdated because they need to be reviewed at least after five years. The findings demonstrate that most universities lack the language policy implementation plans. The nonexistence of the language policy implementation plan adversely affects the implementation of the language policy. The study recommends that universities should provide the learning resources in African languages to meet the demands of the students. To maximise the success, students should be examined in any official languages of the university. The language policy implementation plans should be developed urgently so as to improve language policy implementation in universities. , Le thesisi iphonononge iindlela zokusetyenziswa komgaqo-nkqubo wolwimi kwiiyunivesithi ezichongiweyo zaseMzantsi Afrika. Umgaqo-siseko waseMzantsi Afrika (1996) athathela ingqalelo iilwimi ezisemthethweni ezilishumi elinanye, isiNgesi, isiBhulu, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, Sepedi, SiSwati, Tshivenda neXitsonga. Ezi lwimi zisemthethweni zifanele ukuba zisetyenziswe ngokulinganayo kuzo zonke iinkalo. Ukusetyenziswa kweelwimi kubalulekile kakhulu kwimfundo yabantwana kuwo onke amanqanaba emfundo kodwa olu phando lugxile ekusetyenzisweni komgaqo-nkqubo wolwimi kwiiyunivesithi. Uninzi lweeyunivesithi zinayo imigaqo-nkqubo yolwimi kodwa ingxaki isekusetyenzisweni kwaloo migaqo-nkqubo yolwimi. Ezona njongo zolu phando kukuphonononga ukuba iiyunivesithi ziyisebenzisa njani na imigaqo-nkqubo yolwimi ukuze abafundi bafikelele kwaye baphumelele ezifundweni kwakhona nokugocagoca izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi nokuhlola ukusebenza kwezo zicwangciso. Ulwimi ngundoqo kwimpumelelo yabafundi kwaye umyinge wokusetyenziswa kweelwimi zabafundi ekufundeni kwabo kuthe kwaphandwa. Esi sifundo sisekelwe kwiindlela zocwangciso-lwimi: Ulwimi njengengxaki, ulwimi njengelungelo nolwimi njengesixhobo (Ruiz, 1984). Le thesisi esebenzise indlela yophando entlantlu-mbini (eyobunjani neyobungakanani) kunye noyilo lwendibaniso kokunxuseneyo. Idatha yathi yaqokelelwa kwiiyunivesithi ezilishumi elinanye eMzantsi Afrika kwaye abathabathi nxaxheba babandakanya ilungu lesigqeba solawulo, ilungu lekomiti yeelwimi eyunivesithi nomhlohli wolwimi; kunye nabafundi abakunyaka wesithathu kwizifundo zabo kwiyunivesithi nganye. Idatha yaqokelelwa kubadlulisi-lwazi abaphambili beeyunivesithi ngodliwano-ndlebe oluqingqiweyo. Abafundi abalishumi elinesine bathi bathabathi inxaxheba kuqokelelo lwedatha ngokuthi bagcwalise uludwe lwemibuzo eyayicwangcisiwe. Umaxwebhu omgaqo-nkqubo wolwimi athi achongwa ukuze kubekho ukuqondakala phakathi kokusetyenziswa kolwimi kunye nokumgaqo-nkqubo wolwimi. Uhlalutyo ngokomxholo lwathi lwasetyenziswa ukuhlalutya ulwazi olwabhalwayo luvela kudliwano-ndlebe olwashicilelwayo, idatha eyayisuka kubafundi yathi yahlalutywa ngokusebenzisa uhlalutyo ngokwenkcazelo nangokuthelekelela kunye neStatistical Pakage for Social Sciences (SPSS) njengesixhobo senkcukacha-manani kwaye uhlalutyo loxwebhu lwathi lwasetyenziswa ukuhlalutya imigaqo-nkqubo yolwimi. Iziphumo zibonakalisa ukuba iiyunivesithi zizibophelele ekufikelelekeni kwabafundi kumaziko emfundo ephakamileyo. Impumelelo yabafundi ithi ithityazwe kukusetyenziswa kolwimi olunye apho uninzi lweeyunivesithi zisebenzisa isiNgesi kuphela njengolwimi lokufunda nokufundisa. Ukusetyenziswa kolwimi olunye kuthi kuchaphazela gwenxa impumelelo yabafundi nokuqhuba ngcono ezifundweni. Iziphumo zibonakalisa ukuba kukho imfuno emmandla kubafundi yokuba izixhobo zokufunda nokufundisa zifumaneke nangeelwimi zesiNtu. Inyathelo elihle lelokuba zonke iiyunivesithi ezichongiweyo zinayo imigaqo-nkqubo yolwimi kodwa imigaqo-nkqubo yolwimi emininzi midala kuba ifanelwe ukuba iphononongwe emva kweminyaka emihlanu ubuncinane. Iziphumo zibonakalisa ukuba iiyunivesithi azinazo izicwangciso zokusetyenziswa kwemigaqo-nkqubo yolwimi. Ukungabikho kwesicwangciso sokusetyenziswa komgaqo-nkqubo wolwimi kuchaphazela gwenxa ukusetyenziswa kwawo. Olu phando lundulula ukuba iiyunivesithi zifanele ukuba zibonelele ngezixhobo zokufunda nokufundisa ezingeelwimi zesiNtu ukukhawulelana neemfuno zabafundi. Ukwandisa impumelelo, abafundi kufanele ukuba bavavanywe ngalo naluphi na ulwimi olusemthethweni lweyunivesithi. Izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi zifanele ukuba ziveliswe njengenyewe engxamisekileyo ukuze kuphuculwe ukusetyenziswa kwemigaqo- nkqubo yolwimi kwiiyunivesithi.
- Full Text:
- Date Issued: 2018
- Authors: Somlata, Zakhile
- Date: 2018
- Subjects: Language policy South Africa , Translanguaging (Linguistics) , Language and education South Africa , Language and languages Study and teaching South Africa , Education, Higher South Africa , Multilingualism South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62571 , vital:28208
- Description: This thesis evaluated the language policy implementation strategies used in selected universities of South Africa. The Constitution of the Republic of South African (1996) recognises eleven official languages, namely: English, Afrikaans, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, SiSwati, Sepedi, Tshivenda and Xitsonga. These official languages should enjoy the parity of esteem in all domains. The language practices are very important in the education of students at all levels of education but this study focuses on the language policy implementation in universities. Most universities of South Africa have their language policies but the dilemma is on the implementation of those language policies. The overarching aim of this study is to evaluate how university use language policy for access and success of the students and to assess the language policy implementation strategies, monitoring and evaluation. The language is central to the success of the students and this study further investigated to what extent are the universities use the linguistic repertoires of the students in their education. This study is rooted in orientations of language planning: Language as problem, language as right and language as resource (Ruiz, 1984). This thesis employed a mixed methods approach (qualitative and quantitative method) with convergent parallel design. The data was collected from eleven universities of South Africa and the participants in each university were the "Key informants" (experts and insiders) which comprised of member of Executive Management, a member of the Institutional Language Committee and a language lecturer; and a cohort of forty third year students. The Key informants participated in the qualitative data collection through the structured interviews. The forty third year students participated in the quantitative data collected through survey questionnaires. The language policy documents of the universities were also sampled to get a better understanding of the real language practices and the language policy. The thematic analysis was used to analyse transcripts that were developed from the interviews, data from the students was analysed through descriptive and inferential analyses with Statistical Package for the Social Sciences (SPSS) as a statistical test and document analysis was used to analyse the language policies; The findings show that universities have commitment to access of the students to institutions of Higher Education. The success of the students is being thwarted by the monolingual approach where most of the universities use English only as the medium of instruction. The monolingual approach negatively affects the academic success and excellent academic performance of the majority of students. The findings show that there is high demand from the students that the course materials should be provided in African languages. All selected universities have their language policy which is something positive but most of them are outdated because they need to be reviewed at least after five years. The findings demonstrate that most universities lack the language policy implementation plans. The nonexistence of the language policy implementation plan adversely affects the implementation of the language policy. The study recommends that universities should provide the learning resources in African languages to meet the demands of the students. To maximise the success, students should be examined in any official languages of the university. The language policy implementation plans should be developed urgently so as to improve language policy implementation in universities. , Le thesisi iphonononge iindlela zokusetyenziswa komgaqo-nkqubo wolwimi kwiiyunivesithi ezichongiweyo zaseMzantsi Afrika. Umgaqo-siseko waseMzantsi Afrika (1996) athathela ingqalelo iilwimi ezisemthethweni ezilishumi elinanye, isiNgesi, isiBhulu, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, Sepedi, SiSwati, Tshivenda neXitsonga. Ezi lwimi zisemthethweni zifanele ukuba zisetyenziswe ngokulinganayo kuzo zonke iinkalo. Ukusetyenziswa kweelwimi kubalulekile kakhulu kwimfundo yabantwana kuwo onke amanqanaba emfundo kodwa olu phando lugxile ekusetyenzisweni komgaqo-nkqubo wolwimi kwiiyunivesithi. Uninzi lweeyunivesithi zinayo imigaqo-nkqubo yolwimi kodwa ingxaki isekusetyenzisweni kwaloo migaqo-nkqubo yolwimi. Ezona njongo zolu phando kukuphonononga ukuba iiyunivesithi ziyisebenzisa njani na imigaqo-nkqubo yolwimi ukuze abafundi bafikelele kwaye baphumelele ezifundweni kwakhona nokugocagoca izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi nokuhlola ukusebenza kwezo zicwangciso. Ulwimi ngundoqo kwimpumelelo yabafundi kwaye umyinge wokusetyenziswa kweelwimi zabafundi ekufundeni kwabo kuthe kwaphandwa. Esi sifundo sisekelwe kwiindlela zocwangciso-lwimi: Ulwimi njengengxaki, ulwimi njengelungelo nolwimi njengesixhobo (Ruiz, 1984). Le thesisi esebenzise indlela yophando entlantlu-mbini (eyobunjani neyobungakanani) kunye noyilo lwendibaniso kokunxuseneyo. Idatha yathi yaqokelelwa kwiiyunivesithi ezilishumi elinanye eMzantsi Afrika kwaye abathabathi nxaxheba babandakanya ilungu lesigqeba solawulo, ilungu lekomiti yeelwimi eyunivesithi nomhlohli wolwimi; kunye nabafundi abakunyaka wesithathu kwizifundo zabo kwiyunivesithi nganye. Idatha yaqokelelwa kubadlulisi-lwazi abaphambili beeyunivesithi ngodliwano-ndlebe oluqingqiweyo. Abafundi abalishumi elinesine bathi bathabathi inxaxheba kuqokelelo lwedatha ngokuthi bagcwalise uludwe lwemibuzo eyayicwangcisiwe. Umaxwebhu omgaqo-nkqubo wolwimi athi achongwa ukuze kubekho ukuqondakala phakathi kokusetyenziswa kolwimi kunye nokumgaqo-nkqubo wolwimi. Uhlalutyo ngokomxholo lwathi lwasetyenziswa ukuhlalutya ulwazi olwabhalwayo luvela kudliwano-ndlebe olwashicilelwayo, idatha eyayisuka kubafundi yathi yahlalutywa ngokusebenzisa uhlalutyo ngokwenkcazelo nangokuthelekelela kunye neStatistical Pakage for Social Sciences (SPSS) njengesixhobo senkcukacha-manani kwaye uhlalutyo loxwebhu lwathi lwasetyenziswa ukuhlalutya imigaqo-nkqubo yolwimi. Iziphumo zibonakalisa ukuba iiyunivesithi zizibophelele ekufikelelekeni kwabafundi kumaziko emfundo ephakamileyo. Impumelelo yabafundi ithi ithityazwe kukusetyenziswa kolwimi olunye apho uninzi lweeyunivesithi zisebenzisa isiNgesi kuphela njengolwimi lokufunda nokufundisa. Ukusetyenziswa kolwimi olunye kuthi kuchaphazela gwenxa impumelelo yabafundi nokuqhuba ngcono ezifundweni. Iziphumo zibonakalisa ukuba kukho imfuno emmandla kubafundi yokuba izixhobo zokufunda nokufundisa zifumaneke nangeelwimi zesiNtu. Inyathelo elihle lelokuba zonke iiyunivesithi ezichongiweyo zinayo imigaqo-nkqubo yolwimi kodwa imigaqo-nkqubo yolwimi emininzi midala kuba ifanelwe ukuba iphononongwe emva kweminyaka emihlanu ubuncinane. Iziphumo zibonakalisa ukuba iiyunivesithi azinazo izicwangciso zokusetyenziswa kwemigaqo-nkqubo yolwimi. Ukungabikho kwesicwangciso sokusetyenziswa komgaqo-nkqubo wolwimi kuchaphazela gwenxa ukusetyenziswa kwawo. Olu phando lundulula ukuba iiyunivesithi zifanele ukuba zibonelele ngezixhobo zokufunda nokufundisa ezingeelwimi zesiNtu ukukhawulelana neemfuno zabafundi. Ukwandisa impumelelo, abafundi kufanele ukuba bavavanywe ngalo naluphi na ulwimi olusemthethweni lweyunivesithi. Izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi zifanele ukuba ziveliswe njengenyewe engxamisekileyo ukuze kuphuculwe ukusetyenziswa kwemigaqo- nkqubo yolwimi kwiiyunivesithi.
- Full Text:
- Date Issued: 2018
Participation in the anti-sexual violence silent protest: a sexual citizenship perspective
- Authors: Chitiki, Elizabeth
- Date: 2018
- Subjects: Sex crimes Campus violence -- South Africa -- Prevention Rape victims -- Services for -- Political aspects -- South Africa Anti-rape movement Rape -- Case studies Sexual orientation
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/62917 , vital:28310
- Description: There is a growing body of research on sexual citizenship that focuses attention on gender and which bridges the gap between public and private life in order to rethink citizenship from a feminist perspective. This is in contrast to understandings of citizenship that promote policies of sexual regulation and a heteronormative ideal of citizenship. My research takes the form of a qualitative case study. Using data from two focus group discussions, fifteen personal diaries, as well as social media posts, I analyse participation in the Silent Protest, an annual anti-rape protest, through the lens of sexual citizenship. I look at how participation in the protest promotes or inhibits inclusive and process-based understandings of sexual violence and sexualities issues. Data were analysed using thematic analysis and the results of the analysis are presented into two parts. The first part of the analysis discusses the politics of affect and witnessing as two processes through which allies’ understandings of sexual violence are shaped. The second part of analysis shows that the Silent Protest contributes to people’s knowledge and understandings of sexual violence in relation to sexualities in a range of ways. Examples of inclusive understandings are: (1) insights about rape in relation to gender and heteronormative inequalities, culture and patriarchal dominance; (2) understanding of critical sexual citizenship in relation to sexual violence; and (3) understanding of politics of recognition (the need for recognition of the importance of safe spaces for formal and informal support for victim-survivors and recognition of victim-survivors’ identities). However, some of the understandings are limited to emotion and affect dynamics. In some ways, therefore, the Silent Protest fails to promote understandings significant to inclusive citizenship, including understandings of entitlements to non-discriminatory sexual health care services and legal services.
- Full Text:
- Date Issued: 2018
- Authors: Chitiki, Elizabeth
- Date: 2018
- Subjects: Sex crimes Campus violence -- South Africa -- Prevention Rape victims -- Services for -- Political aspects -- South Africa Anti-rape movement Rape -- Case studies Sexual orientation
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/62917 , vital:28310
- Description: There is a growing body of research on sexual citizenship that focuses attention on gender and which bridges the gap between public and private life in order to rethink citizenship from a feminist perspective. This is in contrast to understandings of citizenship that promote policies of sexual regulation and a heteronormative ideal of citizenship. My research takes the form of a qualitative case study. Using data from two focus group discussions, fifteen personal diaries, as well as social media posts, I analyse participation in the Silent Protest, an annual anti-rape protest, through the lens of sexual citizenship. I look at how participation in the protest promotes or inhibits inclusive and process-based understandings of sexual violence and sexualities issues. Data were analysed using thematic analysis and the results of the analysis are presented into two parts. The first part of the analysis discusses the politics of affect and witnessing as two processes through which allies’ understandings of sexual violence are shaped. The second part of analysis shows that the Silent Protest contributes to people’s knowledge and understandings of sexual violence in relation to sexualities in a range of ways. Examples of inclusive understandings are: (1) insights about rape in relation to gender and heteronormative inequalities, culture and patriarchal dominance; (2) understanding of critical sexual citizenship in relation to sexual violence; and (3) understanding of politics of recognition (the need for recognition of the importance of safe spaces for formal and informal support for victim-survivors and recognition of victim-survivors’ identities). However, some of the understandings are limited to emotion and affect dynamics. In some ways, therefore, the Silent Protest fails to promote understandings significant to inclusive citizenship, including understandings of entitlements to non-discriminatory sexual health care services and legal services.
- Full Text:
- Date Issued: 2018
Biochemical characterisation and small molecule modulation of the interaction between two cytosolic Hsp70s from Trypanosoma brucei and potential co-chaperones
- Authors: Bentley, Stephen John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63402 , vital:28407
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
- Authors: Bentley, Stephen John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63402 , vital:28407
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
On becoming literate in English: a literate life history study of selected Grade 12 learners in a Namibian secondary school
- Authors: Kangootui, Angela Lydia
- Date: 2018
- Subjects: English language -- Study and teaching (Secondary) -- Namibia -- Omaheke , Second language acquisition -- Omaheke , Language and languages -- Study and teaching -- Namibia -- Omaheke , Namibia. Ministry of Basic Education, Sport, and Culture
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/62252 , vital:28147
- Description: This study sought to investigate English literate journeys of selected Grade 12 learners who come from educationally disempowering home backgrounds, and who ‘meet’ informal and/or formal exposure to English language mainly within the confines of school hours. Located within the qualitative, interpretive life history study design, the study used questionnaire and learners’ autobiographies to generate data. These data were then subjected to explore the literate journey of these learners in English as a second language through a comprehensive descriptive analysis. The study was conducted in an urban high school in Omaheke region, Namibia, and the research site and study participants were selected purposively. Theoretically, the study drew from Krashen’s (1981) Second Language Acquisition Theory, which offered this study the five hypotheses that were used as categories to generate, analyse, interpret and discuss data. Research findings reveal that, for various reasons discussed in the study, there is minimal parental involvement in the English literacy journey of their children at home. These include parents not reading regularly to their children, not encouraging visits to the library and the shortage of literacy materials such as newspapers and magazines. The educational level of parents is also a major contributing factor in the literacy journey of their children. The contribution of the community towards the literacy journey in English as a second language of these learners was minimal since the vernacular languages or Afrikaans were used to communicate. At the school level it was found that the attitude of some teachers was a hindrance, as was the way they taught. The use of the mother tongue during teaching also had an effect on the literacy development of the learners. Although the different methods used by various teachers at school level contributed in a way towards literacy development of the learners at school, the huge number of learners in the classrooms was a force to be reckoned with. It is hoped that the study’s findings will assist the Ministry of Basic Education Arts and Culture (MBEAC) in Namibia in informing the type of syllabus content and pedagogical practices to be utilised in teaching English as a Second Language.
- Full Text:
- Date Issued: 2018
- Authors: Kangootui, Angela Lydia
- Date: 2018
- Subjects: English language -- Study and teaching (Secondary) -- Namibia -- Omaheke , Second language acquisition -- Omaheke , Language and languages -- Study and teaching -- Namibia -- Omaheke , Namibia. Ministry of Basic Education, Sport, and Culture
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/62252 , vital:28147
- Description: This study sought to investigate English literate journeys of selected Grade 12 learners who come from educationally disempowering home backgrounds, and who ‘meet’ informal and/or formal exposure to English language mainly within the confines of school hours. Located within the qualitative, interpretive life history study design, the study used questionnaire and learners’ autobiographies to generate data. These data were then subjected to explore the literate journey of these learners in English as a second language through a comprehensive descriptive analysis. The study was conducted in an urban high school in Omaheke region, Namibia, and the research site and study participants were selected purposively. Theoretically, the study drew from Krashen’s (1981) Second Language Acquisition Theory, which offered this study the five hypotheses that were used as categories to generate, analyse, interpret and discuss data. Research findings reveal that, for various reasons discussed in the study, there is minimal parental involvement in the English literacy journey of their children at home. These include parents not reading regularly to their children, not encouraging visits to the library and the shortage of literacy materials such as newspapers and magazines. The educational level of parents is also a major contributing factor in the literacy journey of their children. The contribution of the community towards the literacy journey in English as a second language of these learners was minimal since the vernacular languages or Afrikaans were used to communicate. At the school level it was found that the attitude of some teachers was a hindrance, as was the way they taught. The use of the mother tongue during teaching also had an effect on the literacy development of the learners. Although the different methods used by various teachers at school level contributed in a way towards literacy development of the learners at school, the huge number of learners in the classrooms was a force to be reckoned with. It is hoped that the study’s findings will assist the Ministry of Basic Education Arts and Culture (MBEAC) in Namibia in informing the type of syllabus content and pedagogical practices to be utilised in teaching English as a Second Language.
- Full Text:
- Date Issued: 2018
Young men’s talk about menstruation and hegemonic masculinity in the South African context: a discursive analysis
- Authors: Glover, Jonathan
- Date: 2018
- Subjects: Menstruation -- Social aspects -- -- South Africa -- Eastern Cape , Hegemony -- South Africa -- Eastern Cape , Masculinity -- South Africa -- Eastern Cape , Sex role -- South Africa -- Eastern Cape , Men -- Attitudes , Men -- Psychology , Human body -- Social aspects -- South Africa -- Eastern Cape , Men's studies -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/60244 , vital:27758
- Description: Current research in the sub-Saharan and other resource poor contexts indicates the largely negative social constructions of menstruation and menstruating women. Young men have been shown to reproduce these negative constructions and reinforce the stigmatized status of menstruation in these contexts. To my knowledge no studies have examined the ways in which young men talk about menstruation and menstruating women in South Africa. In this research, I aimed to explore the ways in which young men (in a resource poor area in the Eastern Cape) talk about menstruation in with their male peers in a focus group context and how this talk serves to enable specific subject positions (both masculine and feminine) that may reproduce, comply with and resist constructions of hegemonic masculinity (as outlined in previous South African research). By drawing on Raewyn Connell’s influential framework of masculinities and augmenting this with Margaret Wetherell and Nigel Edley’s contributions, this research adds to the growing body of research on masculinities in the South African context. I utilized a discursive framework in which to understand the interpretative repertoires drawn on in everyday talk about menstruation and the specific subject positions made available by these. Purposive sampling was used to recruit a total of 37 participants from two former Department of Education and Training schools in the Eastern Cape. Participants were young ‘black’ men with a mean age of 18.3 In analyzing and interpreting the data two overarching patterns emerged. In the first, the participants discursively distanced themselves from menstruation (and femininity in general) in order to avoid possible marginalisation and subordination in relation to local hegemonic masculine ideals. In doing this, the participants drew on a number of interpretative repertoires including: a dualistic repertoire, a bad (versus ideal) femininity repertoire and an abject femininity repertoire, which assisted in creating numerous subject positions. These subject positions allowed the young men to align themselves closer to hegemonic masculine ideals, and create distance by positioning menstruating women as the ‘other’. In the second overarching pattern, menstruation was constructed as a threat to masculine identity; within this construction, the young men discursively negotiated the ideological dilemmas surrounding this ‘highly feminine’ topic in ways that bolstered their positions within the gender hierarchy. Overall, hegemonic masculinities in this context were discursively reproduced and complied with in the participants’ accounts.
- Full Text:
- Date Issued: 2018
- Authors: Glover, Jonathan
- Date: 2018
- Subjects: Menstruation -- Social aspects -- -- South Africa -- Eastern Cape , Hegemony -- South Africa -- Eastern Cape , Masculinity -- South Africa -- Eastern Cape , Sex role -- South Africa -- Eastern Cape , Men -- Attitudes , Men -- Psychology , Human body -- Social aspects -- South Africa -- Eastern Cape , Men's studies -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/60244 , vital:27758
- Description: Current research in the sub-Saharan and other resource poor contexts indicates the largely negative social constructions of menstruation and menstruating women. Young men have been shown to reproduce these negative constructions and reinforce the stigmatized status of menstruation in these contexts. To my knowledge no studies have examined the ways in which young men talk about menstruation and menstruating women in South Africa. In this research, I aimed to explore the ways in which young men (in a resource poor area in the Eastern Cape) talk about menstruation in with their male peers in a focus group context and how this talk serves to enable specific subject positions (both masculine and feminine) that may reproduce, comply with and resist constructions of hegemonic masculinity (as outlined in previous South African research). By drawing on Raewyn Connell’s influential framework of masculinities and augmenting this with Margaret Wetherell and Nigel Edley’s contributions, this research adds to the growing body of research on masculinities in the South African context. I utilized a discursive framework in which to understand the interpretative repertoires drawn on in everyday talk about menstruation and the specific subject positions made available by these. Purposive sampling was used to recruit a total of 37 participants from two former Department of Education and Training schools in the Eastern Cape. Participants were young ‘black’ men with a mean age of 18.3 In analyzing and interpreting the data two overarching patterns emerged. In the first, the participants discursively distanced themselves from menstruation (and femininity in general) in order to avoid possible marginalisation and subordination in relation to local hegemonic masculine ideals. In doing this, the participants drew on a number of interpretative repertoires including: a dualistic repertoire, a bad (versus ideal) femininity repertoire and an abject femininity repertoire, which assisted in creating numerous subject positions. These subject positions allowed the young men to align themselves closer to hegemonic masculine ideals, and create distance by positioning menstruating women as the ‘other’. In the second overarching pattern, menstruation was constructed as a threat to masculine identity; within this construction, the young men discursively negotiated the ideological dilemmas surrounding this ‘highly feminine’ topic in ways that bolstered their positions within the gender hierarchy. Overall, hegemonic masculinities in this context were discursively reproduced and complied with in the participants’ accounts.
- Full Text:
- Date Issued: 2018
Beasts we love
- Authors: Masolane, Tseliso Chrisjan
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , Detective and mystery stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63098 , vital:28363
- Description: My thesis is a novella in flash, written as political crime fiction. It is set in contemporary South Africa and tells the story of Rafau Lekopo, a teacher from a little township called Dikgohlong, whose life is changed forever after he finds his wife and the mayor in bed and shoots them both dead. The information contained within the dead mayor's notebook proves to be explosive, showing that the mayor is far more than he seems, and that he is in fact in the employ of a foreign intelligence service. After his release from prison, the embittered Lekopo sets about his revenge against powerful men who abuse their political power. He takes refuge in Lesotho, masterminds a series of heists, car-hijackings and human trafficking, and expands his syndication back in South Africa. Using the contacts and information from the mayor's notebook, he manipulates the Lesotho government into a diplomatic feud with South Africa which treatens to escalate into a military conflict.
- Full Text:
- Date Issued: 2018
- Authors: Masolane, Tseliso Chrisjan
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , Detective and mystery stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63098 , vital:28363
- Description: My thesis is a novella in flash, written as political crime fiction. It is set in contemporary South Africa and tells the story of Rafau Lekopo, a teacher from a little township called Dikgohlong, whose life is changed forever after he finds his wife and the mayor in bed and shoots them both dead. The information contained within the dead mayor's notebook proves to be explosive, showing that the mayor is far more than he seems, and that he is in fact in the employ of a foreign intelligence service. After his release from prison, the embittered Lekopo sets about his revenge against powerful men who abuse their political power. He takes refuge in Lesotho, masterminds a series of heists, car-hijackings and human trafficking, and expands his syndication back in South Africa. Using the contacts and information from the mayor's notebook, he manipulates the Lesotho government into a diplomatic feud with South Africa which treatens to escalate into a military conflict.
- Full Text:
- Date Issued: 2018
Wagon bridges of the Eastern Cape, c. 1840 – 1900: the contribution of engineering to infrastructural development
- Authors: Walters, Dennis Evelyn
- Date: 2018
- Subjects: Bridges Design and construction 19th century , Civil engineers South Africa Cape of Good Hope , Great Britain. Crown Agents' Office , Public works Great Britain Colonies , Wagon trains South Africa Cape of Good Hope
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63877 , vital:28500
- Description: This thesis examines an aspect of economic and technological history which has been little explored in South African history. It argues that the military subjugation and the economic development of the Cape Colony, and particularly of the Eastern Cape, were contingent upon good transportation. The geography of the country, which included relatively impassable mountains and numerous often flooded rivers, necessitated bridges as well as roads. Both were expensive. As a leader in industrial technology, Britain was well placed to extend bridge-building skills to its colonies. This thesis examines the processes by which a small and undeveloped colony strove to create an efficient technological infrastructure. As wagon traffic increased through progress, delays in crossing rivers became a hindrance leading to agitation for bridges. It will be shown that the construction of wagon bridges over the numerous rivers encountered in the Eastern Cape Colony was imperative for the initial free flow of military forces and for later commercial expansion as new towns were established. The eastward expansion was led by the military during the frontier wars followed by the Royal Engineers who built roads and bridges along the eastern frontier. The new Colonial Secretary John Montagu, who arrived in 1843, boosted the colonial finances by overhauling the administration. He established the Central Road Board, an organisation that would drive the building of mountain passes, roads and bridges. The Public Works Department succeeded the Central Road Board and with the financial intervention of the Crown Agents for the Colonies, carried on with an extensive programme of road and bridge building. From the 1870s wagon bridge building lagged behind the huge railway building enterprise in response to the opening up of the diamond and gold mines. The final quarter of the 19th century saw increased bridge building activity in the Eastern Cape with the construction of many iron lattice girder, stone masonry arch and timber trestle bridges. The surviving bridges remain as mute testimony to the skill and expertise of British engineers such as Lewis, Woodifield, Robinson, Fforde, Wakefield, Berkley, Grier, Newey, Westhoven and others.
- Full Text:
- Date Issued: 2018
- Authors: Walters, Dennis Evelyn
- Date: 2018
- Subjects: Bridges Design and construction 19th century , Civil engineers South Africa Cape of Good Hope , Great Britain. Crown Agents' Office , Public works Great Britain Colonies , Wagon trains South Africa Cape of Good Hope
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63877 , vital:28500
- Description: This thesis examines an aspect of economic and technological history which has been little explored in South African history. It argues that the military subjugation and the economic development of the Cape Colony, and particularly of the Eastern Cape, were contingent upon good transportation. The geography of the country, which included relatively impassable mountains and numerous often flooded rivers, necessitated bridges as well as roads. Both were expensive. As a leader in industrial technology, Britain was well placed to extend bridge-building skills to its colonies. This thesis examines the processes by which a small and undeveloped colony strove to create an efficient technological infrastructure. As wagon traffic increased through progress, delays in crossing rivers became a hindrance leading to agitation for bridges. It will be shown that the construction of wagon bridges over the numerous rivers encountered in the Eastern Cape Colony was imperative for the initial free flow of military forces and for later commercial expansion as new towns were established. The eastward expansion was led by the military during the frontier wars followed by the Royal Engineers who built roads and bridges along the eastern frontier. The new Colonial Secretary John Montagu, who arrived in 1843, boosted the colonial finances by overhauling the administration. He established the Central Road Board, an organisation that would drive the building of mountain passes, roads and bridges. The Public Works Department succeeded the Central Road Board and with the financial intervention of the Crown Agents for the Colonies, carried on with an extensive programme of road and bridge building. From the 1870s wagon bridge building lagged behind the huge railway building enterprise in response to the opening up of the diamond and gold mines. The final quarter of the 19th century saw increased bridge building activity in the Eastern Cape with the construction of many iron lattice girder, stone masonry arch and timber trestle bridges. The surviving bridges remain as mute testimony to the skill and expertise of British engineers such as Lewis, Woodifield, Robinson, Fforde, Wakefield, Berkley, Grier, Newey, Westhoven and others.
- Full Text:
- Date Issued: 2018
Development and assessment of a smart thermosetting intranasal hydrogel for lamotrigine
- Authors: Melamane, Siyabonga
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62975 , vital:28349
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Melamane, Siyabonga
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62975 , vital:28349
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Evaluating metabolism-induced toxicity using a non-hepatic cell line
- Authors: Weyers, Carli
- Date: 2018
- Subjects: Cytochrome P-450 , Drugs Metabolism , Drugs Design
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/61950 , vital:28087
- Description: The drug discovery pipeline is a complicated process taking roughly 15 years to complete, costing in excess of $1 billion per new chemical entity. It has been estimated that for every 100, 000 promising hit or lead compounds, only one will make it onto the market due to numerous drug candidates being discarded because of many complications. One such complication is metabolism-induced toxicity. Accordingly, an early understanding of the metabolism of any new chemical entity is becoming an integral part of the pipeline. In order to explore this, various methods have been developed including in silico and in vitro techniques. One such method involves performing cell viability assays on human liver cancer cell lines, which overexpress specific metabolic cytochrome P450 enzymes. If a toxic metabolite is produced it would result in reduced cell viability of the transformed cell line in comparison to a control. Since the liver is the primary site of metabolism in the human body, we were curious as to the extent to which background metabolism may play a role in the degree to which toxic metabolites would be produced in these cell lines. The aim of this project, therefore, was to establish if a non-hepatic cell-based system which overexpresses CYP3A4 could be used to detect the metabolism and any subsequent toxicity of compounds which have been reported to be substrates of the CYP450 enzyme. The HEK293 cell line was stably transfected with a plasmid vector for human CYP3A4 to create a model overexpression system for our metabolism studies. The activity of the enzyme was confirmed using the substrate, 7-benzyloxy-4-trifluoromethyl-coumarin. Subsequently, cytotoxicity testing was done on four known pharmaceuticals reported to generate toxic metabolites in hepatic cell-based assays. In silico metabolic predictions on the four known compounds were performed and compared to the results of published literature. Finally, the metabolism of one compound was studied using a combination of high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) in order to detect predicted metabolites. We observed no change in cellular toxicity nor did we detect the formation of metabolites, even though the overexpressed CYP3A4 enzyme was active. The results suggest that caution should be taken when interpreting the results of cell-based metabolism studies, and background metabolism may play a significant role in the data. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2018
- Full Text:
- Date Issued: 2018
- Authors: Weyers, Carli
- Date: 2018
- Subjects: Cytochrome P-450 , Drugs Metabolism , Drugs Design
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/61950 , vital:28087
- Description: The drug discovery pipeline is a complicated process taking roughly 15 years to complete, costing in excess of $1 billion per new chemical entity. It has been estimated that for every 100, 000 promising hit or lead compounds, only one will make it onto the market due to numerous drug candidates being discarded because of many complications. One such complication is metabolism-induced toxicity. Accordingly, an early understanding of the metabolism of any new chemical entity is becoming an integral part of the pipeline. In order to explore this, various methods have been developed including in silico and in vitro techniques. One such method involves performing cell viability assays on human liver cancer cell lines, which overexpress specific metabolic cytochrome P450 enzymes. If a toxic metabolite is produced it would result in reduced cell viability of the transformed cell line in comparison to a control. Since the liver is the primary site of metabolism in the human body, we were curious as to the extent to which background metabolism may play a role in the degree to which toxic metabolites would be produced in these cell lines. The aim of this project, therefore, was to establish if a non-hepatic cell-based system which overexpresses CYP3A4 could be used to detect the metabolism and any subsequent toxicity of compounds which have been reported to be substrates of the CYP450 enzyme. The HEK293 cell line was stably transfected with a plasmid vector for human CYP3A4 to create a model overexpression system for our metabolism studies. The activity of the enzyme was confirmed using the substrate, 7-benzyloxy-4-trifluoromethyl-coumarin. Subsequently, cytotoxicity testing was done on four known pharmaceuticals reported to generate toxic metabolites in hepatic cell-based assays. In silico metabolic predictions on the four known compounds were performed and compared to the results of published literature. Finally, the metabolism of one compound was studied using a combination of high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) in order to detect predicted metabolites. We observed no change in cellular toxicity nor did we detect the formation of metabolites, even though the overexpressed CYP3A4 enzyme was active. The results suggest that caution should be taken when interpreting the results of cell-based metabolism studies, and background metabolism may play a significant role in the data. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2018
- Full Text:
- Date Issued: 2018
Preimages for SHA-1
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
Demographic change in the Upper Tsitsa Catchment: the integration of census and land cover data for 2001 and 2011
- Authors: Hodgson, Danuta Lorina
- Date: 2018
- Subjects: Land use -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Thematic maps -- South Africa -- Eastern Cape , Population density -- South Africa -- Eastern Cape , Mzimvubu River Watershed (South Africa) -- Census , Upper Tsitsa Catchment (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57296 , vital:26870
- Description: The purpose of this research was to determine if the integration of census and land cover data could provide evidence of spatial patterns and temporal change for the Upper Tsitsa Catchment. This thesis contributed to academic literature with regards to dasymetric mapping and provided a database for the Ntabelanga and Laleni Ecological Infrastructure Project. The study took place in the Upper Tsitsa Catchment which is located in the north-eastern region of the Eastern Cape and falls within the uMzimvubu Catchment. South Africa National Population Censuses for 2001 and 2011 and the National Land Cover data sets for 2000 and 2013/14 were used to create dasymetric maps depicting demographic changes over time for the catchment area. Spatial statistics were performed on the dasymetric and choropleth map to determine the accuracy of the data that was created. From the results, it was found that although the statistics were skewed, the method was more accurate in displaying the population densities, which was noted during the sampling process of the spatial analysis. It was found that there had been a decrease in the population density within the catchment. This affected the density of several other variables such as population race group, language and employment status statistics as decreases in these values could be due to individuals migrating out of the catchment as well as socio-economic upliftment, such as having better access to services. The use of dasymetric mapping allowed an accurate representation of the population density from the census data to be created. The results of the dasymetric mapping were more accurate as they depicted where the population within the enumeration areas were located, and recognised that some areas were populated while some areas were not. To conclude, it was found that using dasymetric mapping provided reliable and useful data about population density and enables comparison over time.
- Full Text:
- Date Issued: 2018
- Authors: Hodgson, Danuta Lorina
- Date: 2018
- Subjects: Land use -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Thematic maps -- South Africa -- Eastern Cape , Population density -- South Africa -- Eastern Cape , Mzimvubu River Watershed (South Africa) -- Census , Upper Tsitsa Catchment (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57296 , vital:26870
- Description: The purpose of this research was to determine if the integration of census and land cover data could provide evidence of spatial patterns and temporal change for the Upper Tsitsa Catchment. This thesis contributed to academic literature with regards to dasymetric mapping and provided a database for the Ntabelanga and Laleni Ecological Infrastructure Project. The study took place in the Upper Tsitsa Catchment which is located in the north-eastern region of the Eastern Cape and falls within the uMzimvubu Catchment. South Africa National Population Censuses for 2001 and 2011 and the National Land Cover data sets for 2000 and 2013/14 were used to create dasymetric maps depicting demographic changes over time for the catchment area. Spatial statistics were performed on the dasymetric and choropleth map to determine the accuracy of the data that was created. From the results, it was found that although the statistics were skewed, the method was more accurate in displaying the population densities, which was noted during the sampling process of the spatial analysis. It was found that there had been a decrease in the population density within the catchment. This affected the density of several other variables such as population race group, language and employment status statistics as decreases in these values could be due to individuals migrating out of the catchment as well as socio-economic upliftment, such as having better access to services. The use of dasymetric mapping allowed an accurate representation of the population density from the census data to be created. The results of the dasymetric mapping were more accurate as they depicted where the population within the enumeration areas were located, and recognised that some areas were populated while some areas were not. To conclude, it was found that using dasymetric mapping provided reliable and useful data about population density and enables comparison over time.
- Full Text:
- Date Issued: 2018
Formulation of an enzyme cocktail, HoloMix, using cellulolytic and xylanolytic enzyme core-sets for effective degradation of various pre-treated hardwoods
- Authors: Malgas, Samkelo
- Date: 2018
- Subjects: Biomass , Cellulase , Hardwoods , Xylanases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/62827 , vital:28297 , DOI https://doi.org/10.21504/10962/62827
- Description: Currently, there is a growing interest in utilising hardwoods as feedstocks for bioethanol production due to the vast advantages they have over other feedstocks for fermentable sugar production. In this study, two selected hardwoods, Acacia and Populus spp., were subjected to two pre-treatment processes (Sodium chlorite delignification and Steam explosion) and compared with respect to how these pre-treatments affect their enzymatic saccharification. Hardwoods were selected for this study, because hardwoods are easier to delignify when compared to softwoods, and therefore their polysaccharides are more easily accessible by enzymes for the purpose of producing fermentable sugars. Currently available commercial enzyme mixtures have been developed for optimal hydrolysis of acid-pre-treated corn stover and are therefore not optimal for saccharification of pre-treated hardwoods. In this work, we attempted the empirical design of a hardwood specific enzyme cocktail, HoloMix. Firstly, a cellulolytic core-set, CelMix (in a ratio of Egl 68%: Cel7A 17%: Cel6A 6%: Bgl1 9%), for the optimal release of glucose, and a xylanolytic core-set, XynMix (in a ratio of Xyn2A 60%: XT6 20%: AguA 11%: SXA 9%), for the optimal release of xylose, were formulated using an empirical enzyme ratio approach after biochemically characterising these enzymes. As it is well ̶ known that biomass pre-treatment may result in the generation of compounds that hamper enzymatic hydrolysis and microbial fermentation, the effects of these compounds on CelMix and XynMix were evaluated. Using the optimised CelMix and XynMix cocktails, a HoloMix cocktail was established for optimal reducing sugar, glucose and xylose release from the various pre-treated hardwoods. For delignified biomass, the optimized HoloMix consisted of CelMix to XynMix at 75% to 25% protein loading, while for the untreated and steam exploded biomass the HoloMix consisted of CelMix to XynMix at 93.75% to 6.25% protein loading. Sugar release by the HoloMix at a loading of 27.5 mg protein/g of biomass (or 55 mg protein/g of glucan) after 24 h gave 70-100% sugar yield. Treatment of the hardwoods with a laccase from Agaricus bisporus, especially wood biomass with a higher proportion of lignin, significantly improved saccharification by the formulated HoloMix enzyme cocktails. This study provided insights into the enzymatic hydrolysis of various pre-treated hardwood substrates and assessed whether the same lignocellulolytic cocktail can be used to efficiently hydrolyse different hardwood species. The present study also demonstrated that the hydrolysis efficiency of the optimised HoloMix was comparable to (if not better) than commercial enzyme preparations during hardwood biomass saccharification. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2018
- Full Text:
- Date Issued: 2018
- Authors: Malgas, Samkelo
- Date: 2018
- Subjects: Biomass , Cellulase , Hardwoods , Xylanases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/62827 , vital:28297 , DOI https://doi.org/10.21504/10962/62827
- Description: Currently, there is a growing interest in utilising hardwoods as feedstocks for bioethanol production due to the vast advantages they have over other feedstocks for fermentable sugar production. In this study, two selected hardwoods, Acacia and Populus spp., were subjected to two pre-treatment processes (Sodium chlorite delignification and Steam explosion) and compared with respect to how these pre-treatments affect their enzymatic saccharification. Hardwoods were selected for this study, because hardwoods are easier to delignify when compared to softwoods, and therefore their polysaccharides are more easily accessible by enzymes for the purpose of producing fermentable sugars. Currently available commercial enzyme mixtures have been developed for optimal hydrolysis of acid-pre-treated corn stover and are therefore not optimal for saccharification of pre-treated hardwoods. In this work, we attempted the empirical design of a hardwood specific enzyme cocktail, HoloMix. Firstly, a cellulolytic core-set, CelMix (in a ratio of Egl 68%: Cel7A 17%: Cel6A 6%: Bgl1 9%), for the optimal release of glucose, and a xylanolytic core-set, XynMix (in a ratio of Xyn2A 60%: XT6 20%: AguA 11%: SXA 9%), for the optimal release of xylose, were formulated using an empirical enzyme ratio approach after biochemically characterising these enzymes. As it is well ̶ known that biomass pre-treatment may result in the generation of compounds that hamper enzymatic hydrolysis and microbial fermentation, the effects of these compounds on CelMix and XynMix were evaluated. Using the optimised CelMix and XynMix cocktails, a HoloMix cocktail was established for optimal reducing sugar, glucose and xylose release from the various pre-treated hardwoods. For delignified biomass, the optimized HoloMix consisted of CelMix to XynMix at 75% to 25% protein loading, while for the untreated and steam exploded biomass the HoloMix consisted of CelMix to XynMix at 93.75% to 6.25% protein loading. Sugar release by the HoloMix at a loading of 27.5 mg protein/g of biomass (or 55 mg protein/g of glucan) after 24 h gave 70-100% sugar yield. Treatment of the hardwoods with a laccase from Agaricus bisporus, especially wood biomass with a higher proportion of lignin, significantly improved saccharification by the formulated HoloMix enzyme cocktails. This study provided insights into the enzymatic hydrolysis of various pre-treated hardwood substrates and assessed whether the same lignocellulolytic cocktail can be used to efficiently hydrolyse different hardwood species. The present study also demonstrated that the hydrolysis efficiency of the optimised HoloMix was comparable to (if not better) than commercial enzyme preparations during hardwood biomass saccharification. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2018
- Full Text:
- Date Issued: 2018
An analysis, from a South African case law perspective, of the deductibility of losses due to embezzlement, fraud, theft, damages and compensation
- Authors: Jachi, Adelaide Gamuchirai
- Date: 2018
- Subjects: South Africa. Income Tax Act, 1962 , Tax deductions -- South Africa , Taxation -- Law and legislation -- South Africa , Tax courts -- South Africa , Tax administration and procedure -- South Africa , Tax accounting -- South Africa , Income tax deductions for losses -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/60855 , vital:27846
- Description: When calculating the income tax payable for a year of assessment, a taxpayer deducts from his or her or its income, allowable deductions in terms of the preamble to section 11 and section 11(a) as read with section 23(g) of the Income Tax Act, 58 of 1962. Amongst the expenditure and losses incurred by a taxpayer during a year of assessment, a claim may be sought for the deduction of losses incurred due to embezzlement, fraud and theft as well as damages and compensation. The requirements of the preamble and section 11(a) include the requirement that expenditure and losses must be incurred “in the production of the income”. Losses incurred due to defalcations, as well as expenditure on damages and compensation must satisfy this requirement to be allowed as deductions. The objective of the research was to analyse the judicial decisions dealing with “in the production of the income” in granting a deduction for income tax purposes in cases dealing with embezzlement, fraud and theft, and damages and compensation, to establish why the courts grant or disallow the deduction of expenditure and losses. A doctrinal research methodology was applied to the research. The provisions of the Income Tax Act, relevant case law relating to embezzlement, fraud and theft, and damages and compensation, and the contributions of the revenue authority and tax experts in articles of accredited journals, textbooks and other writings were analysed. The major conclusions drawn from the research were that losses due to defalcations are regarded as having been incurred “in the production of the income” if the taxpayer discharges the onus of proof that the risk of the act leading to misappropriation is an incidental risk of the business. Expenditure on damages and compensation is deductible provided the expense is attached to the performance of a business operation bona fide performed for the purpose of earning income and the expense is so closely connected with the business operation as to be regarded as part of the cost of performing it. Where negligence is attached to an expense or loss, the South African courts have held that negligence does not increase the likelihood of disallowing an expense or loss as not having been incurred “in the production of the income”.
- Full Text:
- Date Issued: 2018
- Authors: Jachi, Adelaide Gamuchirai
- Date: 2018
- Subjects: South Africa. Income Tax Act, 1962 , Tax deductions -- South Africa , Taxation -- Law and legislation -- South Africa , Tax courts -- South Africa , Tax administration and procedure -- South Africa , Tax accounting -- South Africa , Income tax deductions for losses -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/60855 , vital:27846
- Description: When calculating the income tax payable for a year of assessment, a taxpayer deducts from his or her or its income, allowable deductions in terms of the preamble to section 11 and section 11(a) as read with section 23(g) of the Income Tax Act, 58 of 1962. Amongst the expenditure and losses incurred by a taxpayer during a year of assessment, a claim may be sought for the deduction of losses incurred due to embezzlement, fraud and theft as well as damages and compensation. The requirements of the preamble and section 11(a) include the requirement that expenditure and losses must be incurred “in the production of the income”. Losses incurred due to defalcations, as well as expenditure on damages and compensation must satisfy this requirement to be allowed as deductions. The objective of the research was to analyse the judicial decisions dealing with “in the production of the income” in granting a deduction for income tax purposes in cases dealing with embezzlement, fraud and theft, and damages and compensation, to establish why the courts grant or disallow the deduction of expenditure and losses. A doctrinal research methodology was applied to the research. The provisions of the Income Tax Act, relevant case law relating to embezzlement, fraud and theft, and damages and compensation, and the contributions of the revenue authority and tax experts in articles of accredited journals, textbooks and other writings were analysed. The major conclusions drawn from the research were that losses due to defalcations are regarded as having been incurred “in the production of the income” if the taxpayer discharges the onus of proof that the risk of the act leading to misappropriation is an incidental risk of the business. Expenditure on damages and compensation is deductible provided the expense is attached to the performance of a business operation bona fide performed for the purpose of earning income and the expense is so closely connected with the business operation as to be regarded as part of the cost of performing it. Where negligence is attached to an expense or loss, the South African courts have held that negligence does not increase the likelihood of disallowing an expense or loss as not having been incurred “in the production of the income”.
- Full Text:
- Date Issued: 2018
Rhodes University 2018 Graduation Ceremony: 1820 Settlers' National Monument, Saturday, 7 April at 09:30
- Authors: Rhodes University
- Date: 2018
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/64624 , vital:28566 , https://www.youtube.com/watch?v=I1inTS4jwWE , https://www.youtube.com/watch?v=mPiJiLEQhsE , https://www.youtube.com/watch?v=6kiZBy3D9SM , https://www.youtube.com/watch?v=oVj1DRaA4uw , https://www.youtube.com/watch?v=uvvRxNwFo-o
- Description: Rhodes University 2018 Graduation Programme, 7 April at 09:30: Bachelor’s: Diploma in Fine Art, Bachelor of Arts, Bachelor of Fine Art. Honours: Bachelor of Social Science Honours. Master’s: Master of Fine Art, Master of Social Science. Doctorate: PhD in Humanities.
- Full Text:
- Date Issued: 2018
- Authors: Rhodes University
- Date: 2018
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/64624 , vital:28566 , https://www.youtube.com/watch?v=I1inTS4jwWE , https://www.youtube.com/watch?v=mPiJiLEQhsE , https://www.youtube.com/watch?v=6kiZBy3D9SM , https://www.youtube.com/watch?v=oVj1DRaA4uw , https://www.youtube.com/watch?v=uvvRxNwFo-o
- Description: Rhodes University 2018 Graduation Programme, 7 April at 09:30: Bachelor’s: Diploma in Fine Art, Bachelor of Arts, Bachelor of Fine Art. Honours: Bachelor of Social Science Honours. Master’s: Master of Fine Art, Master of Social Science. Doctorate: PhD in Humanities.
- Full Text:
- Date Issued: 2018
The potential significance of refugia in safeguarding Non-Timber Forest products under Harvesting
- Authors: Mjoli, Nwabisa
- Date: 2018
- Subjects: Non-timber forest products -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60596 , vital:27801
- Description: Many rural households living in and adjacent to forests in South Africa harvest a variety of NonTimber Forest Products (NTFPs) such as wild fruits, fibre, fuelwood, seeds, medicine and bush meat for domestic use, sale and maintaining cultural values. To promote the continued availability of these NTFPs it is important that NTFPs are well maintained and that harvest offtake is sustainable, because if it is not, then the important livelihood function that they fulfil will be jeopardized over time. The role of refugia in conserving pockets of threatened species from overharvesting has rarely been considered. Building on Shackleton et al. (2015), six applications of the concept are considered: size refugia, spatial refugia, cultural/spiritual refugia and physical/habitat refugia. I examined the prevalence and type of refugia for NTFPs at three coastal sites in the Eastern Cape province of South Africa. This was done via several community focus group discussions at each site. Here I report on the role of refugia in offering some safeguard to NTFPs by assessing harvested and non-harvested sites of refugia as well as individual plant species by measuring population density, harvest damage and size class profile. Respondents from the focus group discussions perceived a general decline in the abundance of common, widely used species over the past five decades. Decreasing rainfall and distant farming activities was reported consistently by the majority of the respondents. The most common form of refugia was spatial refugia, followed by cultural/spiritual refugia and physical/habitat refugia. Only six species were identified to be in refugia, namely Cyperus congestus, Cyperus textillis, Millettia grandis, Olea europaea subsp. africana, Phoenix reclinata, and Ptaeroxylon obliquum. Population inventories revealed that regeneration and population densities of some NTFP species in the non-refuge site were adversely affected by harvesting. Populations in refuge sites generally had the largest size classes indicating a regeneration potential but likely to impact regeneration over time if pressures are maintained. Therefore, if refuge sites keep larger individuals, NTFP populations can be maintained. Few studies have critically analyzed the concept of refugia in relation to how NTFPs can be safeguarded and the practical implication of the refuge concept needs to be considered in conservation and strategies and population models.
- Full Text:
- Date Issued: 2018
- Authors: Mjoli, Nwabisa
- Date: 2018
- Subjects: Non-timber forest products -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60596 , vital:27801
- Description: Many rural households living in and adjacent to forests in South Africa harvest a variety of NonTimber Forest Products (NTFPs) such as wild fruits, fibre, fuelwood, seeds, medicine and bush meat for domestic use, sale and maintaining cultural values. To promote the continued availability of these NTFPs it is important that NTFPs are well maintained and that harvest offtake is sustainable, because if it is not, then the important livelihood function that they fulfil will be jeopardized over time. The role of refugia in conserving pockets of threatened species from overharvesting has rarely been considered. Building on Shackleton et al. (2015), six applications of the concept are considered: size refugia, spatial refugia, cultural/spiritual refugia and physical/habitat refugia. I examined the prevalence and type of refugia for NTFPs at three coastal sites in the Eastern Cape province of South Africa. This was done via several community focus group discussions at each site. Here I report on the role of refugia in offering some safeguard to NTFPs by assessing harvested and non-harvested sites of refugia as well as individual plant species by measuring population density, harvest damage and size class profile. Respondents from the focus group discussions perceived a general decline in the abundance of common, widely used species over the past five decades. Decreasing rainfall and distant farming activities was reported consistently by the majority of the respondents. The most common form of refugia was spatial refugia, followed by cultural/spiritual refugia and physical/habitat refugia. Only six species were identified to be in refugia, namely Cyperus congestus, Cyperus textillis, Millettia grandis, Olea europaea subsp. africana, Phoenix reclinata, and Ptaeroxylon obliquum. Population inventories revealed that regeneration and population densities of some NTFP species in the non-refuge site were adversely affected by harvesting. Populations in refuge sites generally had the largest size classes indicating a regeneration potential but likely to impact regeneration over time if pressures are maintained. Therefore, if refuge sites keep larger individuals, NTFP populations can be maintained. Few studies have critically analyzed the concept of refugia in relation to how NTFPs can be safeguarded and the practical implication of the refuge concept needs to be considered in conservation and strategies and population models.
- Full Text:
- Date Issued: 2018
Mannich base metal complexes and their thiocyanate analogues as catalysts in the oxidation of Catechol
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
- Full Text:
- Date Issued: 2018
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
- Full Text:
- Date Issued: 2018
Knowledge practices and student access and success in General Chemistry at a Large South African University
- Authors: Mtombeni, Thabile Nokuthula
- Date: 2018
- Subjects: Chemistry -- Study and teaching (Higher) -- South Africa , Knowledge management , Education, Higher -- Curricula -- South Africa , Critical realism , Social integration -- South Africa , Educational equalization -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62873 , vital:28305
- Description: This dissertation reports on an investigation into the structuring principles of the General Chemistry curriculum at a Large South African University (LSAU). Student learning in the introductory modules of General Chemistry is critical for access to a range of fields since it is a requisite course for a variety of degree programmes. However, there is ample evidence that success in this subject remains a major challenge, particularly for black students. My quest in this study was to explore how the curriculum could enable greater epistemic access and thus include more students in science programmes at the LSAU. I investigated the organising principles underlying the curriculum practices of the General Chemistry module and explored the effects of the curriculum structure on student learning. Theoretically and conceptually, the study was underpinned by a social realist approach which holds that knowledge is stratified, differentiated, and has real emergent properties, powers and effects. The research question that I attempted to answer in this study was: How do knowledge practices privileged in the General Chemistry curriculum at the LSAU enable or constrain student learning? I adopted an intensive research design approach to conduct a qualitative case study using social realism and LCT as theoretical and analytical lenses. I used empirical data such as curriculum documents and interviews with lecturers to uncover the underlying generative mechanisms of the curriculum. I adopted a multi-layered data analysis process to make visible the underlying organising principles informing knowledge practices in the curriculum so that I could explain their potential effects on student learning. The first level of analysis explored the context of the curriculum and associated knowledge practices, and examined the pedagogic discourse evident in the curriculum. The second level of analysis revealed the inner logic structuring the curriculum and the associated knowledge practices. I used Maton’s Legitimation Code Theory (LCT): Specialisation to identify the specialisation codes, gazes and insights generated by the curriculum. For the third level of analysis, LCT: Semantics was used to generate the semantic profiles of learning activities to determine the extent to which the curriculum structure made cumulative learning possible. From the findings, it is evident that the verticality of knowledge in General Chemistry points to a recontextualising principle that prescribes the selection and arrangement of knowledge, and the special relationship of actors and discourses. As a result, the strong framing of the instructional discourse of General Chemistry curriculum structure is likely to constrain epistemological access for large numbers of students. In order to improve epistemological access to the field, weaker framing of the instructional discourse in introductory science is necessary. Weaker framing of the General Chemistry curriculum would require, in particular, changes to pacing, and that the evaluative criteria are made explicit. This is especially necessary when certain abstract and complex curricular content is taught, especially in the first semester. The findings also indicate that the nature of the organising principles in the curriculum are significant for improving epistemological access to knowledge. In terms of LCT: Specialisation, the General Chemistry curriculum generated a knowledge code and downplayed differences among social categories of students, thus positioning all equally in relation to the knowledge and practices of the field. Therefore, the structuring of the curriculum emphasises and legitimates students who have attained specialist knowledge without considering the nature of the new student coming into the educational setting. Simply, what is privileged is both the object of study (theoretical knowledge) and how it is studied (procedural knowledge). This finding is in line with the general outcomes of Chemistry education. In addition, the purist insight generated by the curriculum further attests to where the emphasis is placed in the curriculum. I argue that the lack of social relations in the curriculum poses a challenge for the holistic development of students as science knowers. The analysis of the learning activities shows rapid code shifts that indicate changes in cognitive demand and modes of thinking required of students. I argue that signposting the changes in complexity of knowledge and in the mode of thinking required could make learning, and thus epistemological access, more possible. Given the imperative of access to powerful knowledge, I contend that the curriculum should be reshaped to enable epistemological access for more students.
- Full Text:
- Date Issued: 2018
- Authors: Mtombeni, Thabile Nokuthula
- Date: 2018
- Subjects: Chemistry -- Study and teaching (Higher) -- South Africa , Knowledge management , Education, Higher -- Curricula -- South Africa , Critical realism , Social integration -- South Africa , Educational equalization -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62873 , vital:28305
- Description: This dissertation reports on an investigation into the structuring principles of the General Chemistry curriculum at a Large South African University (LSAU). Student learning in the introductory modules of General Chemistry is critical for access to a range of fields since it is a requisite course for a variety of degree programmes. However, there is ample evidence that success in this subject remains a major challenge, particularly for black students. My quest in this study was to explore how the curriculum could enable greater epistemic access and thus include more students in science programmes at the LSAU. I investigated the organising principles underlying the curriculum practices of the General Chemistry module and explored the effects of the curriculum structure on student learning. Theoretically and conceptually, the study was underpinned by a social realist approach which holds that knowledge is stratified, differentiated, and has real emergent properties, powers and effects. The research question that I attempted to answer in this study was: How do knowledge practices privileged in the General Chemistry curriculum at the LSAU enable or constrain student learning? I adopted an intensive research design approach to conduct a qualitative case study using social realism and LCT as theoretical and analytical lenses. I used empirical data such as curriculum documents and interviews with lecturers to uncover the underlying generative mechanisms of the curriculum. I adopted a multi-layered data analysis process to make visible the underlying organising principles informing knowledge practices in the curriculum so that I could explain their potential effects on student learning. The first level of analysis explored the context of the curriculum and associated knowledge practices, and examined the pedagogic discourse evident in the curriculum. The second level of analysis revealed the inner logic structuring the curriculum and the associated knowledge practices. I used Maton’s Legitimation Code Theory (LCT): Specialisation to identify the specialisation codes, gazes and insights generated by the curriculum. For the third level of analysis, LCT: Semantics was used to generate the semantic profiles of learning activities to determine the extent to which the curriculum structure made cumulative learning possible. From the findings, it is evident that the verticality of knowledge in General Chemistry points to a recontextualising principle that prescribes the selection and arrangement of knowledge, and the special relationship of actors and discourses. As a result, the strong framing of the instructional discourse of General Chemistry curriculum structure is likely to constrain epistemological access for large numbers of students. In order to improve epistemological access to the field, weaker framing of the instructional discourse in introductory science is necessary. Weaker framing of the General Chemistry curriculum would require, in particular, changes to pacing, and that the evaluative criteria are made explicit. This is especially necessary when certain abstract and complex curricular content is taught, especially in the first semester. The findings also indicate that the nature of the organising principles in the curriculum are significant for improving epistemological access to knowledge. In terms of LCT: Specialisation, the General Chemistry curriculum generated a knowledge code and downplayed differences among social categories of students, thus positioning all equally in relation to the knowledge and practices of the field. Therefore, the structuring of the curriculum emphasises and legitimates students who have attained specialist knowledge without considering the nature of the new student coming into the educational setting. Simply, what is privileged is both the object of study (theoretical knowledge) and how it is studied (procedural knowledge). This finding is in line with the general outcomes of Chemistry education. In addition, the purist insight generated by the curriculum further attests to where the emphasis is placed in the curriculum. I argue that the lack of social relations in the curriculum poses a challenge for the holistic development of students as science knowers. The analysis of the learning activities shows rapid code shifts that indicate changes in cognitive demand and modes of thinking required of students. I argue that signposting the changes in complexity of knowledge and in the mode of thinking required could make learning, and thus epistemological access, more possible. Given the imperative of access to powerful knowledge, I contend that the curriculum should be reshaped to enable epistemological access for more students.
- Full Text:
- Date Issued: 2018
Non-government organizations’ adoption of knowledge management systems to enhance service delivery of projects in Grahamstown in the Makana region of the Eastern Cape Province, South Africa
- Authors: Sherif, Nabiha Mohammed
- Date: 2018
- Subjects: Knowledge management , Organizational learning , Non-governmental organizations South Africa Makhanda , Human services South Africa Makhanda
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/61723 , vital:28052
- Description: The object of this research is to enhance the performance of non-government organizations in the Makana region of the Eastern Cape Province of South Africa by the use of knowledge management practices and principles. Non-government organizations face several service delivery challenges that affect their performance. Knowledge management assists in enhancing performance by means of organizational learning. However, the adoption of knowledge management systems has been limited to the profit-making sector. This study includes an evaluation of the contributing factors influencing the adoption of knowledge management and the extent to which non-government organizations use knowledge management to promote organizational learning. An interpretivist, qualitative case study approach was used on five non-government organizations cases from the Makana region of the Eastern Cape Province of South Africa. A suitability profile sampling method was developed to select the non-government organization cases. The participants in the research include non-government organizations’ managers, employees and volunteers. Literature was explored to gain a better understanding of the research area. The research was initiated by an open-ended questionnaire to gather data from the participants, followed by a focus group to enrich the interpretation of the findings. The research proposes a framework to facilitate the adoption of knowledge management systems in non-government organizations. The findings of the research are intended to enhance the performance of non-government organizations projects by means of the use of knowledge management systems.
- Full Text:
- Date Issued: 2018
- Authors: Sherif, Nabiha Mohammed
- Date: 2018
- Subjects: Knowledge management , Organizational learning , Non-governmental organizations South Africa Makhanda , Human services South Africa Makhanda
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/61723 , vital:28052
- Description: The object of this research is to enhance the performance of non-government organizations in the Makana region of the Eastern Cape Province of South Africa by the use of knowledge management practices and principles. Non-government organizations face several service delivery challenges that affect their performance. Knowledge management assists in enhancing performance by means of organizational learning. However, the adoption of knowledge management systems has been limited to the profit-making sector. This study includes an evaluation of the contributing factors influencing the adoption of knowledge management and the extent to which non-government organizations use knowledge management to promote organizational learning. An interpretivist, qualitative case study approach was used on five non-government organizations cases from the Makana region of the Eastern Cape Province of South Africa. A suitability profile sampling method was developed to select the non-government organization cases. The participants in the research include non-government organizations’ managers, employees and volunteers. Literature was explored to gain a better understanding of the research area. The research was initiated by an open-ended questionnaire to gather data from the participants, followed by a focus group to enrich the interpretation of the findings. The research proposes a framework to facilitate the adoption of knowledge management systems in non-government organizations. The findings of the research are intended to enhance the performance of non-government organizations projects by means of the use of knowledge management systems.
- Full Text:
- Date Issued: 2018
Uphando-nzulu lweempendulo ezibhaliweyo zabafundi bamabakala aphezulu emfundo kuncwadi lwesiXhosa
- Authors: Mavela, Xolani Sikhomo
- Date: 2018
- Subjects: Discourse analysis , Anthropological linguistics , Academic writing Study and teaching , Academic writing Evaluation , Linguistics Research
- Language: Xhosa
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63176 , vital:28370
- Description: Kwiziphumo zakutsha nje ezivezwe kwiigridi zocazululo zohlolo loncwadi kwinqanaba lemfundo ephakamileyo (FET), kufumaniseke ukuba abafundi beli nqanaba abaqhubi kakuhle tu kwaphela xa becelwa ukuba babhale iimpendulo zabo kwanezo zimandundu nezikhwencayo kwiitekisi zoncwadi. Ngenxa yesi sizathu, eyona njongo iphambili yolu phando kukuzama ukuyila nokuvelisa isixhobo esinokusetyenziswa ekwaziseni nasekuxhobiseni abafundi besiXhosa abakwinqanaba leFET, ngezakhono zokubhala eziphuhlileyo nezikumgangatho wobhalo lwamaziko emfundo enomsila. Kule meko, ingcali yophando kwezobhalo lolwimi uMartin (2009) uhlomla ngelithi ubhalo olujolise ekunikeni iimpendulo, lubonwa njengohlobo lokubhala oluneengcambu ezimiliselwe ekufundisweni nasekungeneleleni ngokugqibeleleyo ngezakhono zokubhala, bhalo olu lunokuthi emva kwethuba elithile, luphelele kwincochoyi yokushicilelwa, lube ngamaxwebhu ahlelwe ngokusesikweni. Iindlela okanye izixhobo zokubhala eziyilwe ngeenjongo zokunikeza iimpendulo, nezithathwe kuphando lukaFeez noJoyce (1998), zizo eziza kusetyenziswa njengenxalenye yoqeqesho nakumaphulo ongenelelo oluza kuxhasa abafundi besiXhosa benqanaba leFET, nanjengoko ezi zixhobo zibonakala zinegalelo elincomekayo kwindlela ekubhalwa ngayo iimpendulo zeetekisi zoncwadi, ngokuthi zigxile kwezi njongo zilandelayo: (i) Ukunika abafundi ulwazi lokuzuza ulwazi olunzulu nolugqibeleleyo ngokuphathelele kwiinjongo zetekisi. (ii) Ukunika inkcazelo ecacileyo ngokubaluleka kwesakhiwo setekisi kwanokubunjwa kwayo. (iii) Ukuxhobisa abafundi ukuze bakwazi ukuchonga ulwimi oluxabisayo, iimpawu zobume bamagama negrama, kuquka nemiba ephambili yamasiko kwiitekisi zoncwadi. Ngenxa yezi njongo, kufikelelwa kuqikelelo oluthi, kuya kuthi ngokusetyenziswa kwesixhobo sikaFeez noJoyce seZakhono zokuBhala, sixhobo eso sayame kwiinqobo zeNgcingane yokuXabisa okufundwayo nedandalaziswa nguMartin noWhite (2006; 2005 no-2003) nayo le ngcingane eluncedo ekufundisweni kokubhala, abafundi abaninzi boncwadi lwesiXhosa kukholeleka ukuba bakukwazi ukuphuhlisa izakhono zokubhala iitekisi ezinika iimpendulo ezihlahlela imiba ephambili yoncwadi abalufundisiweyo. Olu phando lukwahlabela mgama lubonisa nokuba nezinye izixhobo zoyilo lweetekisi zikaGrabe noKaplan (1996), zinakho ukusetyenziswa ngaxesha linye neenqobo zeNgcingane yokuXabisa okufundwayo, kuquka nemiba yeZakhono zokuBhala, ukuze kwandiswe oku kuphuhliswa kwezakhono zokubhala kubafundi besiXhosa, kungaphelelanga kumabanga aphezulu, koko kufikelelwe nakumabanga asezantsi, nanjengoko kuveziwe kwiziphumo, kwizishwankathelo nakwisiphelo solu phando.
- Full Text:
- Date Issued: 2018
- Authors: Mavela, Xolani Sikhomo
- Date: 2018
- Subjects: Discourse analysis , Anthropological linguistics , Academic writing Study and teaching , Academic writing Evaluation , Linguistics Research
- Language: Xhosa
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63176 , vital:28370
- Description: Kwiziphumo zakutsha nje ezivezwe kwiigridi zocazululo zohlolo loncwadi kwinqanaba lemfundo ephakamileyo (FET), kufumaniseke ukuba abafundi beli nqanaba abaqhubi kakuhle tu kwaphela xa becelwa ukuba babhale iimpendulo zabo kwanezo zimandundu nezikhwencayo kwiitekisi zoncwadi. Ngenxa yesi sizathu, eyona njongo iphambili yolu phando kukuzama ukuyila nokuvelisa isixhobo esinokusetyenziswa ekwaziseni nasekuxhobiseni abafundi besiXhosa abakwinqanaba leFET, ngezakhono zokubhala eziphuhlileyo nezikumgangatho wobhalo lwamaziko emfundo enomsila. Kule meko, ingcali yophando kwezobhalo lolwimi uMartin (2009) uhlomla ngelithi ubhalo olujolise ekunikeni iimpendulo, lubonwa njengohlobo lokubhala oluneengcambu ezimiliselwe ekufundisweni nasekungeneleleni ngokugqibeleleyo ngezakhono zokubhala, bhalo olu lunokuthi emva kwethuba elithile, luphelele kwincochoyi yokushicilelwa, lube ngamaxwebhu ahlelwe ngokusesikweni. Iindlela okanye izixhobo zokubhala eziyilwe ngeenjongo zokunikeza iimpendulo, nezithathwe kuphando lukaFeez noJoyce (1998), zizo eziza kusetyenziswa njengenxalenye yoqeqesho nakumaphulo ongenelelo oluza kuxhasa abafundi besiXhosa benqanaba leFET, nanjengoko ezi zixhobo zibonakala zinegalelo elincomekayo kwindlela ekubhalwa ngayo iimpendulo zeetekisi zoncwadi, ngokuthi zigxile kwezi njongo zilandelayo: (i) Ukunika abafundi ulwazi lokuzuza ulwazi olunzulu nolugqibeleleyo ngokuphathelele kwiinjongo zetekisi. (ii) Ukunika inkcazelo ecacileyo ngokubaluleka kwesakhiwo setekisi kwanokubunjwa kwayo. (iii) Ukuxhobisa abafundi ukuze bakwazi ukuchonga ulwimi oluxabisayo, iimpawu zobume bamagama negrama, kuquka nemiba ephambili yamasiko kwiitekisi zoncwadi. Ngenxa yezi njongo, kufikelelwa kuqikelelo oluthi, kuya kuthi ngokusetyenziswa kwesixhobo sikaFeez noJoyce seZakhono zokuBhala, sixhobo eso sayame kwiinqobo zeNgcingane yokuXabisa okufundwayo nedandalaziswa nguMartin noWhite (2006; 2005 no-2003) nayo le ngcingane eluncedo ekufundisweni kokubhala, abafundi abaninzi boncwadi lwesiXhosa kukholeleka ukuba bakukwazi ukuphuhlisa izakhono zokubhala iitekisi ezinika iimpendulo ezihlahlela imiba ephambili yoncwadi abalufundisiweyo. Olu phando lukwahlabela mgama lubonisa nokuba nezinye izixhobo zoyilo lweetekisi zikaGrabe noKaplan (1996), zinakho ukusetyenziswa ngaxesha linye neenqobo zeNgcingane yokuXabisa okufundwayo, kuquka nemiba yeZakhono zokuBhala, ukuze kwandiswe oku kuphuhliswa kwezakhono zokubhala kubafundi besiXhosa, kungaphelelanga kumabanga aphezulu, koko kufikelelwe nakumabanga asezantsi, nanjengoko kuveziwe kwiziphumo, kwizishwankathelo nakwisiphelo solu phando.
- Full Text:
- Date Issued: 2018