A Century of South African Theatre
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229623 , vital:49694 , xlink:href="https://doi.org/10.1080/10137548.2020.1716515"
- Description: In many ways, this is an updated repackaging of Loren Kruger's seminal work of 20 years ago, Plays, Pageants and the Drama of South Africa (1999). The material has been extensively revised and reworked using similar categories as the first book, including: pageantry and representations of nationhood, neo-colonial theatre, urbanization and its consequences; the rise of Afrikaans theatre; theatres of resistance; black consciousness; and contemporary theatre. Some of these sections have been extended (such as a longer discussion of HIE Dhlomo) and there is also a completely new section which has not been published elsewhere on current theatre trends (cleverly titled “The Constitution of South African Theatre at the Present Time”).
- Full Text:
- Date Issued: 2019
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229623 , vital:49694 , xlink:href="https://doi.org/10.1080/10137548.2020.1716515"
- Description: In many ways, this is an updated repackaging of Loren Kruger's seminal work of 20 years ago, Plays, Pageants and the Drama of South Africa (1999). The material has been extensively revised and reworked using similar categories as the first book, including: pageantry and representations of nationhood, neo-colonial theatre, urbanization and its consequences; the rise of Afrikaans theatre; theatres of resistance; black consciousness; and contemporary theatre. Some of these sections have been extended (such as a longer discussion of HIE Dhlomo) and there is also a completely new section which has not been published elsewhere on current theatre trends (cleverly titled “The Constitution of South African Theatre at the Present Time”).
- Full Text:
- Date Issued: 2019
Woza Albert! (Student Editions)
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229598 , vital:49691 , xlink:href="https://doi.org/10.1080/10137548.2018.1560975"
- Description: Publishing Woza Albert! back in 1983 was a smart move by Methuen Publishing, since it went on to become South Africa’s most canonical dramatic text. As Temple Hauptfleisch points out in his introduction to this new edition, the play has become one of the most anthologized and produced of all South African plays, a regular prescribed work…particularly so in the new curricula introduced since 1994…a major work in the South African literary canon, one of the most studied and produced of the plays from the turbulent 1980s.
- Full Text:
- Date Issued: 2019
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229598 , vital:49691 , xlink:href="https://doi.org/10.1080/10137548.2018.1560975"
- Description: Publishing Woza Albert! back in 1983 was a smart move by Methuen Publishing, since it went on to become South Africa’s most canonical dramatic text. As Temple Hauptfleisch points out in his introduction to this new edition, the play has become one of the most anthologized and produced of all South African plays, a regular prescribed work…particularly so in the new curricula introduced since 1994…a major work in the South African literary canon, one of the most studied and produced of the plays from the turbulent 1980s.
- Full Text:
- Date Issued: 2019
Betty, Zorg and Me
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225552 , vital:49234 , xlink:href="https://doi.org/10.1080/00138398.2019.1636529"
- Description: This essay reminisces about the author’s encounters with Betty Blue at three different stages in his life. It reflects on stylistic elements of the film (as exemplar of Jean-Jacques Beineix’s Cinéma du look) as well as its portrayal of gender, sexuality, artistic aspiration and the concept of freedom. The essay also ruminates on the concept of having favourites and the synchronicity required to make a magical movie.
- Full Text:
- Date Issued: 2019
- Authors: Krueger, Anton
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225552 , vital:49234 , xlink:href="https://doi.org/10.1080/00138398.2019.1636529"
- Description: This essay reminisces about the author’s encounters with Betty Blue at three different stages in his life. It reflects on stylistic elements of the film (as exemplar of Jean-Jacques Beineix’s Cinéma du look) as well as its portrayal of gender, sexuality, artistic aspiration and the concept of freedom. The essay also ruminates on the concept of having favourites and the synchronicity required to make a magical movie.
- Full Text:
- Date Issued: 2019
The morphotactic constraints of verbal extensions in isiXhosa
- Authors: Mkabile, Hlumela
- Date: 2019
- Subjects: Xhosa language -- Grammar
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92849 , vital:30749
- Description: Bantu verbal suffixes, also known as extensions, follow a rather rigid pattern when they attach to the verb. Studies (e.g. Hyman 2002, Good 2005, 2007, among others) have shown that the order followed by these extensions is: Causative, Applicative, Reciprocal, Passive (CARP). Although this pattern is widespread across Bantu, some variations in the ordering of these extensions have been observed in some languages (Kathupa 1991, Simango 1995, Sibanda 2004, among others), which suggests that the template is not as rigid as one might think. This study investigated the morphotactic constraints between four verbal extensions in isiXhosa, the Causative, Applicative, Reciprocal and Passive. It focused on the morphotactics of the transitivising extensions (Causative and Applicative) in the first instance, and morphotactics of the detransitivising extensions (Reciprocal and Passive) in the second instance. The study found that although the co-occurrence of causatives and applicatives is a regular feature in Bantu languages, isiXhosa has restrictions on the co-occurrence of these extensions on some verbs. The study also found that although Causative-Applicative is the expected order the language permits Applicative-Causative in certain contexts. With respect to the detransitivising extensions, the study revealed that there are limited contexts in which these extensions co-occur and, crucially, that these extensions are freely ordered in the language.
- Full Text:
- Date Issued: 2019
- Authors: Mkabile, Hlumela
- Date: 2019
- Subjects: Xhosa language -- Grammar
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92849 , vital:30749
- Description: Bantu verbal suffixes, also known as extensions, follow a rather rigid pattern when they attach to the verb. Studies (e.g. Hyman 2002, Good 2005, 2007, among others) have shown that the order followed by these extensions is: Causative, Applicative, Reciprocal, Passive (CARP). Although this pattern is widespread across Bantu, some variations in the ordering of these extensions have been observed in some languages (Kathupa 1991, Simango 1995, Sibanda 2004, among others), which suggests that the template is not as rigid as one might think. This study investigated the morphotactic constraints between four verbal extensions in isiXhosa, the Causative, Applicative, Reciprocal and Passive. It focused on the morphotactics of the transitivising extensions (Causative and Applicative) in the first instance, and morphotactics of the detransitivising extensions (Reciprocal and Passive) in the second instance. The study found that although the co-occurrence of causatives and applicatives is a regular feature in Bantu languages, isiXhosa has restrictions on the co-occurrence of these extensions on some verbs. The study also found that although Causative-Applicative is the expected order the language permits Applicative-Causative in certain contexts. With respect to the detransitivising extensions, the study revealed that there are limited contexts in which these extensions co-occur and, crucially, that these extensions are freely ordered in the language.
- Full Text:
- Date Issued: 2019
Nonlinear optical responses of targeted phthalocyanines when conjugated with nanomaterials or fabricated into polymer thin films
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
- Full Text:
- Date Issued: 2019
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
- Full Text:
- Date Issued: 2019
Cordidepsine is A Potential New Anti-HIV Depsidone from Cordia millenii
- Zeukang, Rostanie D, Siwe-Noundou, Xavier, Fotsing, Maurice T, Mbafor, Joseph T, Krause, Rui W M, Choudhary, Muhammad I, Atchade, Alex de Theodore
- Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
- Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
- Full Text:
- Date Issued: 2019
- Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
- Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
- Full Text:
- Date Issued: 2019
Managing personal archives in specialised repositories: a case study of Phillip Valentine Tobias collection(s) at the university of the Witwatersrand
- Authors: Marima, Elizabeth Nakai
- Date: 2019
- Subjects: Archives management Institutional repositories
- Language: English
- Type: Thesis , Masters , M LIS
- Identifier: http://hdl.handle.net/10353/11473 , vital:39075
- Description: Personal archives are noncurrent records created by individuals that are selected and kept for their enduring value. They are a record of the past and stand as evidence of what transpired. They make part of repository holdings together with public archives in organisational repositories. Public archives document transactions, statutes, procedures, and regulations. Personal archives contain the documentation of individual lives, emotions, values, experiences and human personality. They seek to reflect the character of the individual who created them. Management of personal archives in repositories refers to their acquisition, collection, arrangement, description, preservation, conservation, creation if access and use. Therefore, the main purpose of this study is to investigate the managing of personal archives in specialized repositories: A case study of Phillip Valentine Tobias Collection(s) at the University of the Witwatersrand, Johannesburg. The study sought to investigate the legal framework that regulates managing of personal archives and the experiences, perceptions and expectations of people managing the personal archives. Furthermore, the study sought to identify strategies of improving the management of personal archives at University of the Witwatersrand, Johannesburg. The study was motivated by the archival theory that conceptualizes grouping of records together for their content and contextual value as evidence with the aim of restating the past. The theory further defines personal archives as records of continued value created by an individual which accumulated naturally, impartially and without prejudice in order to accurately witness the past. The study used a qualitative methodology and was guided by the interpretivist research paradigm. Data was collected using open-ended questions to conduct semi-structured interviews. To complement data, a document analysis, focus group and casual observation were also used. The site of study was University of the Witwatersrand. The total population constituted 41 staff members working in six special repositories with the Phillip Tobias collections at University of the Witwatersrand. The sample size was 25 staff members working in three special repositories. The qualitative data was reported verbartim and the Constant Comparative method was used for data analysis. The findings indicated challenges to the archival theory as the contextual grouping of personal archives was distorted. The study also showed that the archives were xv mismanaged due to framework irregularities, lack of top management support and limited resources. The major resources that were limited were infrastructure, archival ICT systems, human resources and training needs. From the interviews, the research identified strategies of improving the management of personal archives. The study recommended that the university benchmark for archival support strategies and to also engage in existence justification initiatives to harness top management’s attention towards the archive. Out of the identified strategies, the study suggested a tailor made strategy, which combined aspects of each strategy in order to avoid associated challenges.
- Full Text:
- Date Issued: 2019
- Authors: Marima, Elizabeth Nakai
- Date: 2019
- Subjects: Archives management Institutional repositories
- Language: English
- Type: Thesis , Masters , M LIS
- Identifier: http://hdl.handle.net/10353/11473 , vital:39075
- Description: Personal archives are noncurrent records created by individuals that are selected and kept for their enduring value. They are a record of the past and stand as evidence of what transpired. They make part of repository holdings together with public archives in organisational repositories. Public archives document transactions, statutes, procedures, and regulations. Personal archives contain the documentation of individual lives, emotions, values, experiences and human personality. They seek to reflect the character of the individual who created them. Management of personal archives in repositories refers to their acquisition, collection, arrangement, description, preservation, conservation, creation if access and use. Therefore, the main purpose of this study is to investigate the managing of personal archives in specialized repositories: A case study of Phillip Valentine Tobias Collection(s) at the University of the Witwatersrand, Johannesburg. The study sought to investigate the legal framework that regulates managing of personal archives and the experiences, perceptions and expectations of people managing the personal archives. Furthermore, the study sought to identify strategies of improving the management of personal archives at University of the Witwatersrand, Johannesburg. The study was motivated by the archival theory that conceptualizes grouping of records together for their content and contextual value as evidence with the aim of restating the past. The theory further defines personal archives as records of continued value created by an individual which accumulated naturally, impartially and without prejudice in order to accurately witness the past. The study used a qualitative methodology and was guided by the interpretivist research paradigm. Data was collected using open-ended questions to conduct semi-structured interviews. To complement data, a document analysis, focus group and casual observation were also used. The site of study was University of the Witwatersrand. The total population constituted 41 staff members working in six special repositories with the Phillip Tobias collections at University of the Witwatersrand. The sample size was 25 staff members working in three special repositories. The qualitative data was reported verbartim and the Constant Comparative method was used for data analysis. The findings indicated challenges to the archival theory as the contextual grouping of personal archives was distorted. The study also showed that the archives were xv mismanaged due to framework irregularities, lack of top management support and limited resources. The major resources that were limited were infrastructure, archival ICT systems, human resources and training needs. From the interviews, the research identified strategies of improving the management of personal archives. The study recommended that the university benchmark for archival support strategies and to also engage in existence justification initiatives to harness top management’s attention towards the archive. Out of the identified strategies, the study suggested a tailor made strategy, which combined aspects of each strategy in order to avoid associated challenges.
- Full Text:
- Date Issued: 2019
Design and Characterization of a 5 kw Xe-Lamp Solar Simulator
- Authors: Nwodo, Julian Chizoba
- Date: 2019
- Subjects: Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14671 , vital:40042
- Description: The design and characterisation of a 5kW Xenon lamp solar simulator is presented. This was accomplished through considering the design features of an ellipsoidal reflector, Xe lamp characteristics and casing, and power supply; assembly of an ellipsoidal, Xe-lamp simulator; design and building of an automated control system capable of remotely controlling the operating mode of the simulator; establishing the 3 scenarios that must be met to conform to a AAA class simulator; characterization of the simulator in terms of temporal stability, irradiance uniformity and spectral match; and application of the simulator and comparing it with STC rated values. The considerations for the type of material used for housing the components of the solar simulator were made. A 5kW DC power supply and igniter for the Xe-lamp was carefully selected since they provide necessary power for running the simulator. The simulator has the ability to be used in either horizontal or vertical position by adjusting the reflector. An automated control system capable of remotely controlling the operating mode of the simulator was built for this study, this system enables the simulator to be operated in either auto or manual modes. It also incorporates an irradiance, temperature, current and voltage feedback. The characterisation of the solar simulator was over a 2.1 m X 1.6 m test plane. The area under which the characterisation was carried out within the test plane is 110 cm x 129.5 cm. At the end of the steady state large area solar simulator characterisation, a class A spectral match, class A spatial uniformity, and a class B temporal instability was obtained
- Full Text:
- Date Issued: 2019
- Authors: Nwodo, Julian Chizoba
- Date: 2019
- Subjects: Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14671 , vital:40042
- Description: The design and characterisation of a 5kW Xenon lamp solar simulator is presented. This was accomplished through considering the design features of an ellipsoidal reflector, Xe lamp characteristics and casing, and power supply; assembly of an ellipsoidal, Xe-lamp simulator; design and building of an automated control system capable of remotely controlling the operating mode of the simulator; establishing the 3 scenarios that must be met to conform to a AAA class simulator; characterization of the simulator in terms of temporal stability, irradiance uniformity and spectral match; and application of the simulator and comparing it with STC rated values. The considerations for the type of material used for housing the components of the solar simulator were made. A 5kW DC power supply and igniter for the Xe-lamp was carefully selected since they provide necessary power for running the simulator. The simulator has the ability to be used in either horizontal or vertical position by adjusting the reflector. An automated control system capable of remotely controlling the operating mode of the simulator was built for this study, this system enables the simulator to be operated in either auto or manual modes. It also incorporates an irradiance, temperature, current and voltage feedback. The characterisation of the solar simulator was over a 2.1 m X 1.6 m test plane. The area under which the characterisation was carried out within the test plane is 110 cm x 129.5 cm. At the end of the steady state large area solar simulator characterisation, a class A spectral match, class A spatial uniformity, and a class B temporal instability was obtained
- Full Text:
- Date Issued: 2019
Effect of substituents on the photophysical properties and nonlinear optical properties of asymmetrical zinc(II) phthalocyanine when conjugated to semiconductor quantum dots
- Authors: Mgidlana, Sithi
- Date: 2019
- Subjects: Nonlinear optics , Quantum dots , Phthalocyanines , Zinc
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97152 , vital:31404
- Description: Various characterization techniques have been used to characterize the synthesized asymmetrical zinc phthalocyanines (ZnPc) derivatives. Techniques include Ultraviolet-visible (UV-vis) spectrophotometry, matrix assisted laser desorption time of flight mass spectrometry (MALD-TOF MS), proton nuclear magnetic resonance (1H-NMR), elemental analysis and Fourier-transform infra-red spectroscopy (FT-IR). The complexes are covalently linked to core/shell and core/shell/shell semiconductor quantum dots (SQDs) via amide bond formation. Photophysical properties of complexes improved in the presence of semiconductor quantum dots (SQDs). SQDs contain cadmium/telluride (CdTe) as core, coated in the first shell with zinc selenide (ZnSe) or zinc sulfide (ZnS) and with zinc oxide (ZnO) in second shell. The photophysical properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs are investigated in solution. Triplet quantum yields of complexes improved in the presence of semiconductor quantum dots. The optical limiting behaviour of the Pc complexes and conjugates are assessed using the open aperture Z–scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. Pcs complexes showed good nonlinear optical response with higher nonlinear absorption coefficient. The conjugates afforded higher nonlinear absorption coefficient than Pc complexes alone.
- Full Text:
- Date Issued: 2019
- Authors: Mgidlana, Sithi
- Date: 2019
- Subjects: Nonlinear optics , Quantum dots , Phthalocyanines , Zinc
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97152 , vital:31404
- Description: Various characterization techniques have been used to characterize the synthesized asymmetrical zinc phthalocyanines (ZnPc) derivatives. Techniques include Ultraviolet-visible (UV-vis) spectrophotometry, matrix assisted laser desorption time of flight mass spectrometry (MALD-TOF MS), proton nuclear magnetic resonance (1H-NMR), elemental analysis and Fourier-transform infra-red spectroscopy (FT-IR). The complexes are covalently linked to core/shell and core/shell/shell semiconductor quantum dots (SQDs) via amide bond formation. Photophysical properties of complexes improved in the presence of semiconductor quantum dots (SQDs). SQDs contain cadmium/telluride (CdTe) as core, coated in the first shell with zinc selenide (ZnSe) or zinc sulfide (ZnS) and with zinc oxide (ZnO) in second shell. The photophysical properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs are investigated in solution. Triplet quantum yields of complexes improved in the presence of semiconductor quantum dots. The optical limiting behaviour of the Pc complexes and conjugates are assessed using the open aperture Z–scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. Pcs complexes showed good nonlinear optical response with higher nonlinear absorption coefficient. The conjugates afforded higher nonlinear absorption coefficient than Pc complexes alone.
- Full Text:
- Date Issued: 2019
Statistical optimisation of a terbinafine-containing cream
- Authors: Strydom, Lana
- Date: 2019
- Subjects: Chemicals -- Physiological effect , Pharmaceutical chemistry Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44067 , vital:37101
- Description: Terbinafine hydrochloride (TBH) belongs to the allylamine class of antifungals and displays a favourable dermatopharmacokinetic profile, being both lipophilic and keratinophilic. It has thus been included in a variety of topical dosage forms for the treatment of dermatomycoses, many of which have been the subject of optimisation studies, with the purpose of improving the product. Since a TBH-containing cream had not been found in literature to have been optimised before, the aim of this study was to optimise a TBH cream formulation. A TBH cream formulation, suitable for optimisation, was developed. Preformulation tests were undertaken, including active-excipient compatibility testing using a combined thermal method consisting of both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), as well as isothermal stress testing (IST). With the confirmation of the suitability of the selected excipients, development of a suitable TBH cream took place largely by a trial-and-error approach. The choice of a suitable formulation was made based on the physical appearance and viscosity of the cream, for which a viscosity specification was set. The identified TBH cream formulation was evaluated for its physical appearance and physicochemical aspects to confirm its appropriateness for the purpose of further optimisation. Based on literature and observations from the preformulation and formulation stage, factors and responses for study during the optimisation stage were identified to study using a circumscribed central composite design (CCCD) at five levels (-1.612, -1, 0, +1, +1.612). Total percentage of surfactant (TPS), homogenisation speed (HS) and cooling rate (CR), were selected as factors to study their influence on cream viscosity, in vitro TBH release from the cream, as well as the chemical stability of TBH within the cream formulation. Following the application of stepwise multiple linear regression to the mathematical models, a suitable prediction model was only obtained for one response, cream viscosity at a shear rate of 20 s-1. A linear model was also found to fit the data for % in vitro TBH release after one hour, although a low R2 of 0.497 made the model unsuitable for prediction purposes. No mathematical model could be fit to the results for the response assessing the change in TBH concentration following seven days’ storage at accelerated stability conditions. The determination of the optimum TBH cream formulation was made chiefly on the basis of the results for cream viscosity and the optimised formulation was identified to have a predicted viscosity of 8.33 Pa.s and the factor settings to obtain this cream were a CR of 1.3 °C/min, HS set at 3400 rpm, and TPS of 4.2 %. Validation of the optimised TBH cream formulation was performed for cream viscosity at a shear rate of 20 s-1 and revealed that there was good agreement between the measured and predicted viscosity values. The optimised TBH cream underwent rheological characterisation and was compared to the innovator, Lamisil® cream, with both creams found to meet the desirable rheological profile. In vitro release testing (IVRT) was used to compare the release of TBH from the optimised TBH cream and Lamisil® cream, and the optimised TBH cream was found to show much greater TBH release over a six-hour time period than Lamisil® cream. Stability testing of the optimised TBH cream took place at accelerated stability testing conditions of 40 °C ± 2 °C and 75 ± 5 % relative humidity (RH). To assay the formulation and determine content uniformity over the three-month storage period, a suitable stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed and validated. Other cream properties which were tested included: qualitative aspects, viscosity, pH and microbial limits. At the end of the three-month stability testing period, the cream was found to meet most of the specifications set, except for cream homogeneity and viscosity. A TBH cream formulation was thus developed and optimised to meet a certain viscosity specification. Although this formulation was found to meet the viscosity specification on the day after its manufacture, the viscosity was found to increase on storage, such that it was outside the set viscosity specification range.
- Full Text:
- Date Issued: 2019
- Authors: Strydom, Lana
- Date: 2019
- Subjects: Chemicals -- Physiological effect , Pharmaceutical chemistry Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44067 , vital:37101
- Description: Terbinafine hydrochloride (TBH) belongs to the allylamine class of antifungals and displays a favourable dermatopharmacokinetic profile, being both lipophilic and keratinophilic. It has thus been included in a variety of topical dosage forms for the treatment of dermatomycoses, many of which have been the subject of optimisation studies, with the purpose of improving the product. Since a TBH-containing cream had not been found in literature to have been optimised before, the aim of this study was to optimise a TBH cream formulation. A TBH cream formulation, suitable for optimisation, was developed. Preformulation tests were undertaken, including active-excipient compatibility testing using a combined thermal method consisting of both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), as well as isothermal stress testing (IST). With the confirmation of the suitability of the selected excipients, development of a suitable TBH cream took place largely by a trial-and-error approach. The choice of a suitable formulation was made based on the physical appearance and viscosity of the cream, for which a viscosity specification was set. The identified TBH cream formulation was evaluated for its physical appearance and physicochemical aspects to confirm its appropriateness for the purpose of further optimisation. Based on literature and observations from the preformulation and formulation stage, factors and responses for study during the optimisation stage were identified to study using a circumscribed central composite design (CCCD) at five levels (-1.612, -1, 0, +1, +1.612). Total percentage of surfactant (TPS), homogenisation speed (HS) and cooling rate (CR), were selected as factors to study their influence on cream viscosity, in vitro TBH release from the cream, as well as the chemical stability of TBH within the cream formulation. Following the application of stepwise multiple linear regression to the mathematical models, a suitable prediction model was only obtained for one response, cream viscosity at a shear rate of 20 s-1. A linear model was also found to fit the data for % in vitro TBH release after one hour, although a low R2 of 0.497 made the model unsuitable for prediction purposes. No mathematical model could be fit to the results for the response assessing the change in TBH concentration following seven days’ storage at accelerated stability conditions. The determination of the optimum TBH cream formulation was made chiefly on the basis of the results for cream viscosity and the optimised formulation was identified to have a predicted viscosity of 8.33 Pa.s and the factor settings to obtain this cream were a CR of 1.3 °C/min, HS set at 3400 rpm, and TPS of 4.2 %. Validation of the optimised TBH cream formulation was performed for cream viscosity at a shear rate of 20 s-1 and revealed that there was good agreement between the measured and predicted viscosity values. The optimised TBH cream underwent rheological characterisation and was compared to the innovator, Lamisil® cream, with both creams found to meet the desirable rheological profile. In vitro release testing (IVRT) was used to compare the release of TBH from the optimised TBH cream and Lamisil® cream, and the optimised TBH cream was found to show much greater TBH release over a six-hour time period than Lamisil® cream. Stability testing of the optimised TBH cream took place at accelerated stability testing conditions of 40 °C ± 2 °C and 75 ± 5 % relative humidity (RH). To assay the formulation and determine content uniformity over the three-month storage period, a suitable stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed and validated. Other cream properties which were tested included: qualitative aspects, viscosity, pH and microbial limits. At the end of the three-month stability testing period, the cream was found to meet most of the specifications set, except for cream homogeneity and viscosity. A TBH cream formulation was thus developed and optimised to meet a certain viscosity specification. Although this formulation was found to meet the viscosity specification on the day after its manufacture, the viscosity was found to increase on storage, such that it was outside the set viscosity specification range.
- Full Text:
- Date Issued: 2019
In vitro antimalarial, antitrypanosomal and HIV-1 integrase inhibitory activities of two Cameroonian medicinal plants
- Fouokeng, Yannick, Feumo Feusso, H M, Mbosso Teinkela, Jean E, Siwe-Noundou, Xavier, Wintjens, René T, Isaacs, Michelle, Hoppe, Heinrich, Krause, Rui W M, Azébazé, Anatole G B, Vardamides, Juliette C
- Authors: Fouokeng, Yannick , Feumo Feusso, H M , Mbosso Teinkela, Jean E , Siwe-Noundou, Xavier , Wintjens, René T , Isaacs, Michelle , Hoppe, Heinrich , Krause, Rui W M , Azébazé, Anatole G B , Vardamides, Juliette C
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195014 , vital:45519 , xlink:href="https://doi.org/10.1016/j.sajb.2018.10.008"
- Description: Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value more than 10 μg/mL for crude extracts and more than 1 μg/mL for pure compounds. The hexane/ethyl acetate (1:1) fraction of A.klaineanum root bark (AKERF1) and the hexane/ethyl acetate (1:1) fraction of A.klaineanum trunk bark (AKETF1) presented the strongest antiplasmodial activities with IC50 values of 0.4 and 4.4 μg/mL, respectively. Aridanin (4) and antrocarine A(11), as well as the crude extract of D.conocarpa roots (EDCR), AKERF1 and AKETF1 showed moderate trypanocidal effects. The crude extract of A.klaineanum root bark (AKER) and AKETF1 exhibited attractive activities on HIV-1 integrase with IC50 values of 1.96 and 24.04 μg/mL, respectively. The results provide baseline information on the use of A.klaineanum and D.conocarpa extracts, as well as certain components, as sources of new antiplasmodial, antitrypanosomal and anti-HIV drugs.
- Full Text:
- Date Issued: 2019
- Authors: Fouokeng, Yannick , Feumo Feusso, H M , Mbosso Teinkela, Jean E , Siwe-Noundou, Xavier , Wintjens, René T , Isaacs, Michelle , Hoppe, Heinrich , Krause, Rui W M , Azébazé, Anatole G B , Vardamides, Juliette C
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195014 , vital:45519 , xlink:href="https://doi.org/10.1016/j.sajb.2018.10.008"
- Description: Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value more than 10 μg/mL for crude extracts and more than 1 μg/mL for pure compounds. The hexane/ethyl acetate (1:1) fraction of A.klaineanum root bark (AKERF1) and the hexane/ethyl acetate (1:1) fraction of A.klaineanum trunk bark (AKETF1) presented the strongest antiplasmodial activities with IC50 values of 0.4 and 4.4 μg/mL, respectively. Aridanin (4) and antrocarine A(11), as well as the crude extract of D.conocarpa roots (EDCR), AKERF1 and AKETF1 showed moderate trypanocidal effects. The crude extract of A.klaineanum root bark (AKER) and AKETF1 exhibited attractive activities on HIV-1 integrase with IC50 values of 1.96 and 24.04 μg/mL, respectively. The results provide baseline information on the use of A.klaineanum and D.conocarpa extracts, as well as certain components, as sources of new antiplasmodial, antitrypanosomal and anti-HIV drugs.
- Full Text:
- Date Issued: 2019
Synthesis, characterization and anticancer studies of Oxovanadium(iv) Dithiocarbamate complexes
- Authors: Hlobo, Priscilla Vuyiswa
- Date: 2019
- Subjects: Inorganic compounds -- Synthesis Chemistry, Inorganic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19131 , vital:39880
- Description: Eight new oxovanadium(IV) dithiocarbamate complexes, formed by the interaction of vanadyl sulfate pentahydrate and as-synthesized dithiocarbamate ligands, potassium N-morpholine-4- dithiocarbamate ligand (L1), potassium N-piperidinedithiocarbamate (L2), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-diallyldithiocarbamate ligand (L4), potassium N-phenyldithiocarbamate ligand (L5), potassium N-dibenzylminedithiocarbamate ligand (L6), potassium N-(4-methylphenyl)dithiocarbamate ligand (L7), N-(1Himidazoledithiocarbamate) fluoride ligand (L8) in aqueous ethanol are described. The resulting complexes were elemental analyses, molar conductance, infrared, electronic, and nuclear magnetic resonance spectral studies. The spectral studies confirmed the formation of the ligands and complexes. Four complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] derived from potassium N-morpholine-4-dithiocarbamate ligand (L1), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-dibenzylminedithiocarbamate ligand (L6), and N-(1H-imidazoledithiocarbamate) fluoride ligand (L8) were characterized using cyclic voltammetry, to study their electrochemical behavior. Square pyramid oxovanadium(IV) complexes were proposed with the metal ion coordinated to two bidentate dithiocarbamate ligands through sulphur to complete its square pyramidal geometry. The anticancer screening of four oxovanadium(IV) dithiocarbamate complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] are described.
- Full Text:
- Date Issued: 2019
- Authors: Hlobo, Priscilla Vuyiswa
- Date: 2019
- Subjects: Inorganic compounds -- Synthesis Chemistry, Inorganic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19131 , vital:39880
- Description: Eight new oxovanadium(IV) dithiocarbamate complexes, formed by the interaction of vanadyl sulfate pentahydrate and as-synthesized dithiocarbamate ligands, potassium N-morpholine-4- dithiocarbamate ligand (L1), potassium N-piperidinedithiocarbamate (L2), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-diallyldithiocarbamate ligand (L4), potassium N-phenyldithiocarbamate ligand (L5), potassium N-dibenzylminedithiocarbamate ligand (L6), potassium N-(4-methylphenyl)dithiocarbamate ligand (L7), N-(1Himidazoledithiocarbamate) fluoride ligand (L8) in aqueous ethanol are described. The resulting complexes were elemental analyses, molar conductance, infrared, electronic, and nuclear magnetic resonance spectral studies. The spectral studies confirmed the formation of the ligands and complexes. Four complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] derived from potassium N-morpholine-4-dithiocarbamate ligand (L1), potassium N-(4- methoxyphenyl)dithiocarbamate ligand (L3), potassium N-dibenzylminedithiocarbamate ligand (L6), and N-(1H-imidazoledithiocarbamate) fluoride ligand (L8) were characterized using cyclic voltammetry, to study their electrochemical behavior. Square pyramid oxovanadium(IV) complexes were proposed with the metal ion coordinated to two bidentate dithiocarbamate ligands through sulphur to complete its square pyramidal geometry. The anticancer screening of four oxovanadium(IV) dithiocarbamate complexes [VO(L1)2], [VO(L3)2], [VO(L6)2], and [VO(L8)2] are described.
- Full Text:
- Date Issued: 2019
Arbuscular mycorrhizal fungi as a bio-indicator of soil health under agricultural management practices in South Africa
- Authors: Sekgota, Wendy Maphefo
- Date: 2019
- Subjects: Soils -- Quality -- South Africa , Soil fertility -- South Africa , Fungi in agriculture -- South Africa , Mycorrhizal fungi , Vesicular-arbuscular mycorrhizas , Fungi -- Spores , Soils -- Agricultural chemical content
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72161 , vital:30011
- Description: This study investigated the activity of arbuscular mycorrhizal (AM) fungi as a potential biological indicator of soil health under conventional and conservation agricultural management in South Africa. An experimental trial consisting of three replicates plots under conventional and reduced tillage subdivided into twelve treatments of six crops and two fertilizer inputs was assessed over four growing seasons for various AM fungal parameters such as spore density, most probable number (MPN) of propagules percentage root colonisation and easily extractable glomalin (EEG). Cropping combinations were maize monoculture; maize soybean rotation; maize cowpea rotation; maize cowpea intercropping; maize oats intercropping and maize vetch intercropping. Resident AM fungal spore numbers and EEG protein levels were very low and no root colonization was recorded in the first two growing seasons. These findings prompted the need for the inoculation of the study site in the third growing season with a commercial AM fungal product (MycorootTM). Spore numbers, EEG concentrations and percentage root colonisation increased 8 weeks after inoculation but were significantly reduced in the fourth growing season that was not inoculated. MPN infectivity increased with inoculation particularly under conventional tillage and maize monoculture. Resident spore taxa were morphologically identified into three genera Gigaspora, Scutellospora, and Glomus. For the first two growing seasons, the maize roots were heavily colonized by a pathogenic fungus after mycorrhizal inoculation no evidence of pathogenic fungi was observed. In the fourth growing season which did not receive inoculation, root colonization started to decline. Reduced tillage, high fertilizer input combined with maize cowpea rotation (MC) and maize hairy vetch intercropping (Mv) had a significant effect (P = 0.01) on AM fungal spore numbers. Cropping systems and high fertilizer input had a significant effect on EEG concentrations in the second growing season. Overall, fertilizer application and crop type had implications for mycorrhizal activity. The soil health status in this study site was deemed low as measured by the impaired mycorrhizal activity due to agricultural management practices. Field inoculation combined with classical and molecular tools could provide a more realistic assessment of the effect of agricultural management practices on AM fungi as potential bioindicators of soil health. Therefore, AM fungi could be used as bioindicators of soil health under agricultural management practices in South African soil conditions.
- Full Text:
- Date Issued: 2019
- Authors: Sekgota, Wendy Maphefo
- Date: 2019
- Subjects: Soils -- Quality -- South Africa , Soil fertility -- South Africa , Fungi in agriculture -- South Africa , Mycorrhizal fungi , Vesicular-arbuscular mycorrhizas , Fungi -- Spores , Soils -- Agricultural chemical content
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72161 , vital:30011
- Description: This study investigated the activity of arbuscular mycorrhizal (AM) fungi as a potential biological indicator of soil health under conventional and conservation agricultural management in South Africa. An experimental trial consisting of three replicates plots under conventional and reduced tillage subdivided into twelve treatments of six crops and two fertilizer inputs was assessed over four growing seasons for various AM fungal parameters such as spore density, most probable number (MPN) of propagules percentage root colonisation and easily extractable glomalin (EEG). Cropping combinations were maize monoculture; maize soybean rotation; maize cowpea rotation; maize cowpea intercropping; maize oats intercropping and maize vetch intercropping. Resident AM fungal spore numbers and EEG protein levels were very low and no root colonization was recorded in the first two growing seasons. These findings prompted the need for the inoculation of the study site in the third growing season with a commercial AM fungal product (MycorootTM). Spore numbers, EEG concentrations and percentage root colonisation increased 8 weeks after inoculation but were significantly reduced in the fourth growing season that was not inoculated. MPN infectivity increased with inoculation particularly under conventional tillage and maize monoculture. Resident spore taxa were morphologically identified into three genera Gigaspora, Scutellospora, and Glomus. For the first two growing seasons, the maize roots were heavily colonized by a pathogenic fungus after mycorrhizal inoculation no evidence of pathogenic fungi was observed. In the fourth growing season which did not receive inoculation, root colonization started to decline. Reduced tillage, high fertilizer input combined with maize cowpea rotation (MC) and maize hairy vetch intercropping (Mv) had a significant effect (P = 0.01) on AM fungal spore numbers. Cropping systems and high fertilizer input had a significant effect on EEG concentrations in the second growing season. Overall, fertilizer application and crop type had implications for mycorrhizal activity. The soil health status in this study site was deemed low as measured by the impaired mycorrhizal activity due to agricultural management practices. Field inoculation combined with classical and molecular tools could provide a more realistic assessment of the effect of agricultural management practices on AM fungi as potential bioindicators of soil health. Therefore, AM fungi could be used as bioindicators of soil health under agricultural management practices in South African soil conditions.
- Full Text:
- Date Issued: 2019
Bioinformatic analysis, isolation and kinetic characterisation of red algae (Gelidium capense) dehydrogenases
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
Short term stability testing of efavirenz-loaded solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) dispersions
- Makoni, Pedzisai A, Kasongo, Kasongo W, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Kasongo, Kasongo W , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183492 , vital:44000 , xlink:href="https://doi.org/10.3390/pharmaceutics11080397"
- Description: The short term stability of efavirenz-loaded solid lipid nanoparticle and nanostructured lipid carrier dispersions was investigated. Hot High Pressure Homogenization with the capability for scale up production was successfully used to manufacture the nanocarriers without the use of toxic organic solvents for the first time. Glyceryl monostearate and Transcutol® HP were used as the solid and liquid lipids. Tween® 80 was used to stabilize the lipid nanocarriers. A Box-Behnken Design was used to identify the optimum operating and production conditions viz., 1100 bar for 3 cycles for the solid lipid nanoparticles and 1500 bar for 5 cycles for nanostructured lipid carriers. The optimized nanocarriers were predicted to exhibit 10% efavirenz loading with 3% and 4% Tween® 80 for solid lipid nanoparticles and nanostructured lipid carriers, respectively. Characterization of the optimized solid lipid nanoparticle and nanostructured lipid carrier formulations in relation to shape, surface morphology, polymorphism, crystallinity and compatibility revealed stable formulations with particle sizes in the nanometer range had been produced. The nanocarriers had excellent efavirenz loading with the encapsulation efficiency >90%. The optimized nanocarriers exhibited biphasic in vitro release patterns with an initial burst release during the initial 0–3 h followed by sustained release over a 24 h period The colloidal systems showed excellent stability in terms of Zeta potential, particle size, polydispersity index and encapsulation efficiency when stored for 8 weeks at 25 °C/60% RH in comparison to when stored at 40 °C/75% RH. The formulations manufactured using the optimized conditions and composition proved to be physically stable as aqueous dispersions.
- Full Text:
- Date Issued: 2019
- Authors: Makoni, Pedzisai A , Kasongo, Kasongo W , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183492 , vital:44000 , xlink:href="https://doi.org/10.3390/pharmaceutics11080397"
- Description: The short term stability of efavirenz-loaded solid lipid nanoparticle and nanostructured lipid carrier dispersions was investigated. Hot High Pressure Homogenization with the capability for scale up production was successfully used to manufacture the nanocarriers without the use of toxic organic solvents for the first time. Glyceryl monostearate and Transcutol® HP were used as the solid and liquid lipids. Tween® 80 was used to stabilize the lipid nanocarriers. A Box-Behnken Design was used to identify the optimum operating and production conditions viz., 1100 bar for 3 cycles for the solid lipid nanoparticles and 1500 bar for 5 cycles for nanostructured lipid carriers. The optimized nanocarriers were predicted to exhibit 10% efavirenz loading with 3% and 4% Tween® 80 for solid lipid nanoparticles and nanostructured lipid carriers, respectively. Characterization of the optimized solid lipid nanoparticle and nanostructured lipid carrier formulations in relation to shape, surface morphology, polymorphism, crystallinity and compatibility revealed stable formulations with particle sizes in the nanometer range had been produced. The nanocarriers had excellent efavirenz loading with the encapsulation efficiency >90%. The optimized nanocarriers exhibited biphasic in vitro release patterns with an initial burst release during the initial 0–3 h followed by sustained release over a 24 h period The colloidal systems showed excellent stability in terms of Zeta potential, particle size, polydispersity index and encapsulation efficiency when stored for 8 weeks at 25 °C/60% RH in comparison to when stored at 40 °C/75% RH. The formulations manufactured using the optimized conditions and composition proved to be physically stable as aqueous dispersions.
- Full Text:
- Date Issued: 2019
Novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine: an investigation of their inclusion ability
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
Nonlinear optical behavior of n-tuple decker phthalocyanines at the nanosecond regime
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234603 , vital:50212 , xlink:href="https://doi.org/10.1039/C9RA01836K"
- Description: The coordination system of rare-earth n-tuple decker phthalocyanines would be better suited with appropriate metal ions with the correct coordination number and the solvent system of the reaction, amongst other reasons, for the formation of n-tuple decker phthalocyanines. As a result, these complexes are very rare. In this manuscript, we present new n-tuple decker phthalocyanines in the form of double- (complex 2), quadruple- (complex 3a) and sextuple-decker phthalocyanines (complex 3b), all of which contain neodymium and cadmium metal ions. The primary focus is the investigation of the nonlinear optical (NLO) mechanisms responsible for the observed reverse saturable absorption. While the extension of the π-electron system has been found to enhance the nonlinear optical behavior of complexes 3a and 3b, a change in the NLO mechanisms has been observed, with complex 2 lacking the triplet state population, as revealed by a laser flash photolysis technique. It has also been established that the excited state absorption cross sections follow a clear order of magnitude for the complexes under investigation: σ23 (for 3b) > σ23 (for 3a) > σ1m (for 2). This trend evidences the effects of the extension of the π-electron system.
- Full Text:
- Date Issued: 2019
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234603 , vital:50212 , xlink:href="https://doi.org/10.1039/C9RA01836K"
- Description: The coordination system of rare-earth n-tuple decker phthalocyanines would be better suited with appropriate metal ions with the correct coordination number and the solvent system of the reaction, amongst other reasons, for the formation of n-tuple decker phthalocyanines. As a result, these complexes are very rare. In this manuscript, we present new n-tuple decker phthalocyanines in the form of double- (complex 2), quadruple- (complex 3a) and sextuple-decker phthalocyanines (complex 3b), all of which contain neodymium and cadmium metal ions. The primary focus is the investigation of the nonlinear optical (NLO) mechanisms responsible for the observed reverse saturable absorption. While the extension of the π-electron system has been found to enhance the nonlinear optical behavior of complexes 3a and 3b, a change in the NLO mechanisms has been observed, with complex 2 lacking the triplet state population, as revealed by a laser flash photolysis technique. It has also been established that the excited state absorption cross sections follow a clear order of magnitude for the complexes under investigation: σ23 (for 3b) > σ23 (for 3a) > σ1m (for 2). This trend evidences the effects of the extension of the π-electron system.
- Full Text:
- Date Issued: 2019
Extraction, isolation and characterization of oleanolic acid and its analogues from Syzygium aromaticum (cloves) and evaluation of their biological activities
- Authors: khwaza, Vuyolwethu
- Date: 2019
- Subjects: Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19076 , vital:39882
- Description: Pathogenic microorganisms have serious impact on people's lives. Every year, millions of people around the world die of bacterial infections. Resistance to common antibacterial drugs has proven to be a challenging problem in control of bacterial infections. In an attempt to develop an effective and affordable treatment for bacterial infections, oleanolic acid isolated from syzygium aromaticum conjugates incorporating other pharmaceutical scaffolds such as chloroquine derivatives, curcumin, and ergocalciferol etc have been developed. Based on the previous successes of testing combination of antimicrobial drugs and pharmaceutical drugs which appeared to be the promising strategy to overcome treatment failure; a series of hybrid compounds containing oleanolic acid and other pharmaceutical scaffolds were synthesized. 4- Aminoquinoline derivatives were first hybridized with selected organic compounds to form a class of hybrid compounds containing either amide bond or ester bond as a linker between the precursor molecules. Analogues/hybrid compounds can overcome the disadvantages of combination therapy such as drug-drug interaction. The structural effects of this type of conjugation of oleanolic acid and other pharmaceutical scaffolds were characterised by FTIR, Mass Spec and NMR spectroscopy. These compounds were studied along with the monosubstituted oleanolic acid analogues and the organic components in order to compare the effects of the substitution on their biological response.‖ All the synthesized analogues were tested against 11 bacterial strains on both Gram-positive and Gram-negative bacteria. The synthesized compounds showed selectivity and higher activity against Enterococcus faecalis (EF), Klebsiella oxytoca (KO), Escherischia coli (EC), Staphylococcus aureous (SA), Proteus vulgaris (PV) and Bacillus subtilis (BS) with MIC values; ranging between of 1.25 mg/mL to 0.072 mg/mL
- Full Text:
- Date Issued: 2019
- Authors: khwaza, Vuyolwethu
- Date: 2019
- Subjects: Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19076 , vital:39882
- Description: Pathogenic microorganisms have serious impact on people's lives. Every year, millions of people around the world die of bacterial infections. Resistance to common antibacterial drugs has proven to be a challenging problem in control of bacterial infections. In an attempt to develop an effective and affordable treatment for bacterial infections, oleanolic acid isolated from syzygium aromaticum conjugates incorporating other pharmaceutical scaffolds such as chloroquine derivatives, curcumin, and ergocalciferol etc have been developed. Based on the previous successes of testing combination of antimicrobial drugs and pharmaceutical drugs which appeared to be the promising strategy to overcome treatment failure; a series of hybrid compounds containing oleanolic acid and other pharmaceutical scaffolds were synthesized. 4- Aminoquinoline derivatives were first hybridized with selected organic compounds to form a class of hybrid compounds containing either amide bond or ester bond as a linker between the precursor molecules. Analogues/hybrid compounds can overcome the disadvantages of combination therapy such as drug-drug interaction. The structural effects of this type of conjugation of oleanolic acid and other pharmaceutical scaffolds were characterised by FTIR, Mass Spec and NMR spectroscopy. These compounds were studied along with the monosubstituted oleanolic acid analogues and the organic components in order to compare the effects of the substitution on their biological response.‖ All the synthesized analogues were tested against 11 bacterial strains on both Gram-positive and Gram-negative bacteria. The synthesized compounds showed selectivity and higher activity against Enterococcus faecalis (EF), Klebsiella oxytoca (KO), Escherischia coli (EC), Staphylococcus aureous (SA), Proteus vulgaris (PV) and Bacillus subtilis (BS) with MIC values; ranging between of 1.25 mg/mL to 0.072 mg/mL
- Full Text:
- Date Issued: 2019
Germination potential of seeds harvested at the Worcester Veld Reserve
- Authors: Swart, Rudi
- Date: 2019
- Subjects: Ecological disturbances -- South Africa -- Karoo , Environmental degradation -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43923 , vital:37084
- Description: The rangelands of the Succulent Karoo and Nama Karoo biomes are in various states of degradation. The injudicious stocking of overly high numbers of domestic livestock is considered to be the anthropogenic cause of this degradation. The palatable plants of these rangelands have been greatly reduced in number or extirpated from some areas. In order to return palatable plants to degraded rangelands and improve rangeland productivity, many restoration projects have been attempted that involve reseeding. The sowing of seeds into degraded rangelands, or other disturbed areas, has often provided disappointing germination results. This study will attempt to determine what some of the main aspects are that affect Karoo seed germination, both positively and negatively. The specific objectives of the study are to determine the causes of pre-sowing seed mortality, the effect of drying on seed germination, the effect of planting depth on seed germination and the effect of storage time on seed germination. The seeds of four palatable Karoo plant species harvested at the Worcester Veld Reserve were selected to be subjected to germination trails and viability testing. This study uses germination trials under controlled light and temperature conditions, as well as 2, 3, 5-triphenyl tetrazolium chloride tests to determine whether the four species of Karoo seeds harvested at the Worcester Veld Reserve for rangeland reseeding projects are viable and germinable. The practice of drying seeds after harvesting is tested to determine the effect of drying on seed germination. The germination of seed was also tested over 17 intervals of 3 weeks to determine the effect of storage time on seed germinability. Germination trials were also conducted in a nursery to determine whether there was a difference in seedling emergence between seeds planted at 10 mm depth compared to seeds planted on the surface with a partial covering of sand. The seed viability of all four species studied was found to be below 50%. Drying only significantly improved the germination of Osteospermum sinuatum seeds. The seeds of O. sinuatum and Eriocephalus africanus germinated reasonably well throughout the 17 time intervals, while the seeds of Chaetobromus involucratus and Gorteria integrifolia germinated poorly during the first six months after harvesting, after which v germination improved markedly. Seedling emergence of all four species studied was significantly higher when planted at the substrate surface, compared to seeds planted at 10 mm depth. The findings of this study show that while the viability of the seeds harvested for rangeland reseeding projects are quite low, the appropriate pre-treatment, seed age and planting depth will allow a significant increase in germination. This increase in germination should provide a greater chance of establishing palatable plants in rangeland reseeding projects.
- Full Text:
- Date Issued: 2019
- Authors: Swart, Rudi
- Date: 2019
- Subjects: Ecological disturbances -- South Africa -- Karoo , Environmental degradation -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43923 , vital:37084
- Description: The rangelands of the Succulent Karoo and Nama Karoo biomes are in various states of degradation. The injudicious stocking of overly high numbers of domestic livestock is considered to be the anthropogenic cause of this degradation. The palatable plants of these rangelands have been greatly reduced in number or extirpated from some areas. In order to return palatable plants to degraded rangelands and improve rangeland productivity, many restoration projects have been attempted that involve reseeding. The sowing of seeds into degraded rangelands, or other disturbed areas, has often provided disappointing germination results. This study will attempt to determine what some of the main aspects are that affect Karoo seed germination, both positively and negatively. The specific objectives of the study are to determine the causes of pre-sowing seed mortality, the effect of drying on seed germination, the effect of planting depth on seed germination and the effect of storage time on seed germination. The seeds of four palatable Karoo plant species harvested at the Worcester Veld Reserve were selected to be subjected to germination trails and viability testing. This study uses germination trials under controlled light and temperature conditions, as well as 2, 3, 5-triphenyl tetrazolium chloride tests to determine whether the four species of Karoo seeds harvested at the Worcester Veld Reserve for rangeland reseeding projects are viable and germinable. The practice of drying seeds after harvesting is tested to determine the effect of drying on seed germination. The germination of seed was also tested over 17 intervals of 3 weeks to determine the effect of storage time on seed germinability. Germination trials were also conducted in a nursery to determine whether there was a difference in seedling emergence between seeds planted at 10 mm depth compared to seeds planted on the surface with a partial covering of sand. The seed viability of all four species studied was found to be below 50%. Drying only significantly improved the germination of Osteospermum sinuatum seeds. The seeds of O. sinuatum and Eriocephalus africanus germinated reasonably well throughout the 17 time intervals, while the seeds of Chaetobromus involucratus and Gorteria integrifolia germinated poorly during the first six months after harvesting, after which v germination improved markedly. Seedling emergence of all four species studied was significantly higher when planted at the substrate surface, compared to seeds planted at 10 mm depth. The findings of this study show that while the viability of the seeds harvested for rangeland reseeding projects are quite low, the appropriate pre-treatment, seed age and planting depth will allow a significant increase in germination. This increase in germination should provide a greater chance of establishing palatable plants in rangeland reseeding projects.
- Full Text:
- Date Issued: 2019
The development of palladium nanoparticles for radiopharmaceutical application
- Authors: Gandidzanwa, Sendibitiyosi
- Date: 2019
- Subjects: Nanotechnology , Nanostructures Nanofluids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42163 , vital:36631
- Description: The dissertation describes an in-depth synthesis and optimisation of palladium(0) nanoparticles of three distinct size ranges, respective capping agents, and cellular uptake studies using a non-toxic concentration (10 μM), laying a foundation for the design of palladium-based folate receptor-targeted theranostic nanoradiopharmaceutical. In the preliminary selection to determine the optimal diamines for the study, ethylenediamine, hexamethylenediamine, 1,10-diaminodecane, 1,12-diaminododecane, 1,4- diaminobenzene, 4,4’-ethylenedianiline, 1,2-diphenyl-1,2-diaminoethane, and tetraaminophthalocyanine were employed. The characterisation of the nanoparticles obtained from the in situ reduction of palladium(II) salt at room temperature by either 1,2,3- trihydroxybenze (pyrogallol), citric acid, sodium metabisulphite, sodium borohydride, hydrazine hydrate, or formaldehyde was performed. Ethylenediamine and sodium borohydride were found to be the best diamine capping and reducing agent, respectively. Systematic investigations determined that the nanoparticle synthesis was dependent on various reaction parameters: such as reaction temperature, time, reductant reducing power, and capping agents. The parameters effects on the nanoparticle size, morphology, shape, stability, crystallinity, and surface charge were investigated. The optical properties, elemental composition, functional group, concentration and molecular weight for the synthesised nanoparticles or conjugates were determined. These properties were analysed using Ultraviolet–visible spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM) coupled with selective area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), zeta potential (ZP), dynamic light scattering (DLS), elemental analysis (EA), 1H and 13C-nuclear magnetic resonance (1H- and 13CNMR), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and liquid chromatography-mass spectroscopy (LC-MS). The in vitro cytotoxicity, cell uptake, and internalisation studies of palladium nanoparticles (10 μM) ranging in size and different types of capping agent were performed using three breast cancer cell lines: MDA-MB-468 , MCF-7 and MDA-MB-231 , and a non-tumorigenic MCF-10A breast cell line. The cell uptake and internalisation were investigated using ICP-OES and TEM. A high dependence between reduction rate and concentration of palladium precursor was observed for the room temperature synthesis of palladium nanoparticles, and the employed synthesis procedure will be applied to the hot palladium isotope (109Pd). A facile, green, aqueous synthesis route for palladium nanoparticles at room temperature was developed, and the synthesised nanoparticles indicated narrow size distributions. A concentration dependence between cytotoxicity and palladium nanoparticles was observed, with lower concentrations (10 μM) exhibiting minimal cytotoxicity relative to higher concentrations (100 μM). The cellular uptake of palladium nanoparticles was found to be concentration, folate-receptor, capping agent, and cell line proliferation-dependent. Well-defined, monodispersed, and negatively charged folate-ethylenediamine and folate-phthalocyanine capped palladium nanoparticles were taken up by cells, with higher nanoparticle internalisation in folate receptor positive tumorigenic cells relative to folate receptor negative non-tumorigenic cells. It can be concluded that palladium(0) nanoparticles can be synthesised from the reduction of palladium(II) by sodium borohydride at room temperature. The folate-conjugated palladium nanoparticles are non-cytotoxic at 10 μM and were successfully optimised and selectively delivered to folate receptor-positive breast cancer cells (MDA-MB-231 and MCF-7) relative to non-tumorigenic breast cells (MCF-10A) and folate receptor negative cancer cells (MDA-MB-468).
- Full Text:
- Date Issued: 2019
- Authors: Gandidzanwa, Sendibitiyosi
- Date: 2019
- Subjects: Nanotechnology , Nanostructures Nanofluids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42163 , vital:36631
- Description: The dissertation describes an in-depth synthesis and optimisation of palladium(0) nanoparticles of three distinct size ranges, respective capping agents, and cellular uptake studies using a non-toxic concentration (10 μM), laying a foundation for the design of palladium-based folate receptor-targeted theranostic nanoradiopharmaceutical. In the preliminary selection to determine the optimal diamines for the study, ethylenediamine, hexamethylenediamine, 1,10-diaminodecane, 1,12-diaminododecane, 1,4- diaminobenzene, 4,4’-ethylenedianiline, 1,2-diphenyl-1,2-diaminoethane, and tetraaminophthalocyanine were employed. The characterisation of the nanoparticles obtained from the in situ reduction of palladium(II) salt at room temperature by either 1,2,3- trihydroxybenze (pyrogallol), citric acid, sodium metabisulphite, sodium borohydride, hydrazine hydrate, or formaldehyde was performed. Ethylenediamine and sodium borohydride were found to be the best diamine capping and reducing agent, respectively. Systematic investigations determined that the nanoparticle synthesis was dependent on various reaction parameters: such as reaction temperature, time, reductant reducing power, and capping agents. The parameters effects on the nanoparticle size, morphology, shape, stability, crystallinity, and surface charge were investigated. The optical properties, elemental composition, functional group, concentration and molecular weight for the synthesised nanoparticles or conjugates were determined. These properties were analysed using Ultraviolet–visible spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM) coupled with selective area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), zeta potential (ZP), dynamic light scattering (DLS), elemental analysis (EA), 1H and 13C-nuclear magnetic resonance (1H- and 13CNMR), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and liquid chromatography-mass spectroscopy (LC-MS). The in vitro cytotoxicity, cell uptake, and internalisation studies of palladium nanoparticles (10 μM) ranging in size and different types of capping agent were performed using three breast cancer cell lines: MDA-MB-468 , MCF-7 and MDA-MB-231 , and a non-tumorigenic MCF-10A breast cell line. The cell uptake and internalisation were investigated using ICP-OES and TEM. A high dependence between reduction rate and concentration of palladium precursor was observed for the room temperature synthesis of palladium nanoparticles, and the employed synthesis procedure will be applied to the hot palladium isotope (109Pd). A facile, green, aqueous synthesis route for palladium nanoparticles at room temperature was developed, and the synthesised nanoparticles indicated narrow size distributions. A concentration dependence between cytotoxicity and palladium nanoparticles was observed, with lower concentrations (10 μM) exhibiting minimal cytotoxicity relative to higher concentrations (100 μM). The cellular uptake of palladium nanoparticles was found to be concentration, folate-receptor, capping agent, and cell line proliferation-dependent. Well-defined, monodispersed, and negatively charged folate-ethylenediamine and folate-phthalocyanine capped palladium nanoparticles were taken up by cells, with higher nanoparticle internalisation in folate receptor positive tumorigenic cells relative to folate receptor negative non-tumorigenic cells. It can be concluded that palladium(0) nanoparticles can be synthesised from the reduction of palladium(II) by sodium borohydride at room temperature. The folate-conjugated palladium nanoparticles are non-cytotoxic at 10 μM and were successfully optimised and selectively delivered to folate receptor-positive breast cancer cells (MDA-MB-231 and MCF-7) relative to non-tumorigenic breast cells (MCF-10A) and folate receptor negative cancer cells (MDA-MB-468).
- Full Text:
- Date Issued: 2019