(Ferrocenylpyrazolyl) zinc (II) benzoates as catalysts for the ring opening polymerization of ε-caprolactone
- Obuah, Collins, Lochee, Yemanlall, Jordaan, Johan H L, Otto, Daniel P, Nyokong, Tebello, Darkwa, James
- Authors: Obuah, Collins , Lochee, Yemanlall , Jordaan, Johan H L , Otto, Daniel P , Nyokong, Tebello , Darkwa, James
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189515 , vital:44853 , xlink:href="https://doi.org/10.1016/j.poly.2015.02.007"
- Description: The reaction of Zn(OAc)2 and C6H5COOH or 3,5-NO2-C6H3COOH with 3-ferrocenylpyrazolyl-methylenepyridine (L1), 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L2), 3-ferrocenylpyrazolyl-ethylamine (L3) and 3-ferrocenyl-5-pyrazolyl-ethylamine (L4) afford the corresponding complexes [Zn(C6H5COO)2(L1)] (1), [Zn(C6H5COO)2(L2)] (2), [Zn(3,5-NO2-C6H3COO)2(L1)] (3), [Zn(3,5-NO2-C6H3 COO)2(L2)] (4), [Zn(C6H5COO)2(L3)] (5), [Zn(C6H5COO)2(L4)] (6), [Zn(3,5-NO2-C6H3COO)2(L3)] (7) and [Zn(3,5-NO2-C6H3COO)2(L4)] (8). These complexes behave as catalysts for the ring opening polymerization of e-caprolactone to produce polymers with molecular weight that range from 1480 to 7080 g mol1 and exhibited moderate to broad PDIs. Evidence of these complexes acting as catalysts was obtained from both the polymerization data and kinetic studies. The polymerization data show that variation of the [CL]/[C] from 100 to 800 produced PCL with relatively the same molecular weight indicative of a catalyst behavior. The appearance of induction period in kinetic plots strengthens the fact that these complexes are catalysts rather than initiators. MALDI-TOF MS and 1 H NMR data show di-hydroxy end groups, which support the coordination mechanism rather than insertion mechanism. To understand the broad PDIs obtained for some of the polymer, the electronic properties of the zinc complexes were investigated using cyclic voltammetry. The results show that the zinc complexes containing amine based ligands are highly electrophilic therefore making them unstable, hence the broad PDIs observed for zinc complexes containing amine based ligands. Among the eight complexes investigated, complex 7 is the most active catalyst with kp value of 1.18 107 h1 mol1 at 110 C.
- Full Text:
- Date Issued: 2015
- Authors: Obuah, Collins , Lochee, Yemanlall , Jordaan, Johan H L , Otto, Daniel P , Nyokong, Tebello , Darkwa, James
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189515 , vital:44853 , xlink:href="https://doi.org/10.1016/j.poly.2015.02.007"
- Description: The reaction of Zn(OAc)2 and C6H5COOH or 3,5-NO2-C6H3COOH with 3-ferrocenylpyrazolyl-methylenepyridine (L1), 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L2), 3-ferrocenylpyrazolyl-ethylamine (L3) and 3-ferrocenyl-5-pyrazolyl-ethylamine (L4) afford the corresponding complexes [Zn(C6H5COO)2(L1)] (1), [Zn(C6H5COO)2(L2)] (2), [Zn(3,5-NO2-C6H3COO)2(L1)] (3), [Zn(3,5-NO2-C6H3 COO)2(L2)] (4), [Zn(C6H5COO)2(L3)] (5), [Zn(C6H5COO)2(L4)] (6), [Zn(3,5-NO2-C6H3COO)2(L3)] (7) and [Zn(3,5-NO2-C6H3COO)2(L4)] (8). These complexes behave as catalysts for the ring opening polymerization of e-caprolactone to produce polymers with molecular weight that range from 1480 to 7080 g mol1 and exhibited moderate to broad PDIs. Evidence of these complexes acting as catalysts was obtained from both the polymerization data and kinetic studies. The polymerization data show that variation of the [CL]/[C] from 100 to 800 produced PCL with relatively the same molecular weight indicative of a catalyst behavior. The appearance of induction period in kinetic plots strengthens the fact that these complexes are catalysts rather than initiators. MALDI-TOF MS and 1 H NMR data show di-hydroxy end groups, which support the coordination mechanism rather than insertion mechanism. To understand the broad PDIs obtained for some of the polymer, the electronic properties of the zinc complexes were investigated using cyclic voltammetry. The results show that the zinc complexes containing amine based ligands are highly electrophilic therefore making them unstable, hence the broad PDIs observed for zinc complexes containing amine based ligands. Among the eight complexes investigated, complex 7 is the most active catalyst with kp value of 1.18 107 h1 mol1 at 110 C.
- Full Text:
- Date Issued: 2015
A colorimetric probe for dopamine based on gold nanoparticles-electrospun nanofibre composite
- Ngomane, Nokuthula, Torto, Nelson, Krause, Rui W M, Vilakazi, Sibulelo
- Authors: Ngomane, Nokuthula , Torto, Nelson , Krause, Rui W M , Vilakazi, Sibulelo
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195407 , vital:45562 , xlink:href="https://doi.org/10.1016/j.matpr.2015.08.036"
- Description: An easily prepared solid state colorimetric probe for detecting the neurotransmitter dopamine (DA) was developed. The probe, in the form of an electrospun Nylon−6 (N6) nanofibre with embedded un−functionalized gold nanoparticles (UF−AuNPs) produces a clear colour change in the presence of a DA that is detectable by the naked eye. Characterisation of the nanofibre using UV/vis spectroscopy and electron microscopy (TEM) confirmed the formation of the AuNPs in the polymer solution, and that the AuNPs were completely encapsulated within the composite nanofibres before exposure to the analytes. The probe exhibited very high sensitivity towards DA resulting in colour change of the composite fibres from purple to navy blue/black even under low concentrations of DA. The probe was also selective to DA since the colour remained unchanged in the presence of commonly encountered interfering species such as ascorbic acid, uric acid, catechol, epinephrine and norepinephrine. Moreover, the colour change was observed rapid, occurring either immediately on contact with higher concentrations (5 x10−4 M) or within about 3−5 min for the lower concentrations (e.g. 5 x10−7 M). Since this probe does not require the use of any instruments, and is both rapid and stable over time, it can be applied in the field by an inexperienced person.
- Full Text:
- Date Issued: 2015
- Authors: Ngomane, Nokuthula , Torto, Nelson , Krause, Rui W M , Vilakazi, Sibulelo
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195407 , vital:45562 , xlink:href="https://doi.org/10.1016/j.matpr.2015.08.036"
- Description: An easily prepared solid state colorimetric probe for detecting the neurotransmitter dopamine (DA) was developed. The probe, in the form of an electrospun Nylon−6 (N6) nanofibre with embedded un−functionalized gold nanoparticles (UF−AuNPs) produces a clear colour change in the presence of a DA that is detectable by the naked eye. Characterisation of the nanofibre using UV/vis spectroscopy and electron microscopy (TEM) confirmed the formation of the AuNPs in the polymer solution, and that the AuNPs were completely encapsulated within the composite nanofibres before exposure to the analytes. The probe exhibited very high sensitivity towards DA resulting in colour change of the composite fibres from purple to navy blue/black even under low concentrations of DA. The probe was also selective to DA since the colour remained unchanged in the presence of commonly encountered interfering species such as ascorbic acid, uric acid, catechol, epinephrine and norepinephrine. Moreover, the colour change was observed rapid, occurring either immediately on contact with higher concentrations (5 x10−4 M) or within about 3−5 min for the lower concentrations (e.g. 5 x10−7 M). Since this probe does not require the use of any instruments, and is both rapid and stable over time, it can be applied in the field by an inexperienced person.
- Full Text:
- Date Issued: 2015
A comparative photophysicochemical study of phthalocyanines encapsulated in core–shell silica nanoparticles
- Fashina, Adedayo, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Fashina, Adedayo , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189708 , vital:44924 , xlink:href="https://doi.org/10.1016/j.saa.2014.08.062"
- Description: This work presents the synthesis and characterization of a new zinc phthalocyanine complex tetrasubstituted with 3-carboxyphenoxy in the peripheral position. The photophysical properties of the new complex are compared with those of phthalocyanines tetra substituted with 3-carboxyphenoxy or 4- carboxyphenoxy at non-peripheral positions. Three phthalocyanine complexes were encapsulated within silica matrix to form a core shell and the hybrid nanoparticles particles obtained were spherical and mono dispersed. When encapsulated within the silica shell nanoparticles, phthalocyanines showed improved triplet quantum yields and singlet oxygen quantum yields than surface grafted derivatives. The improvements observed could be attributed to the protection provided for the phthalocyanine complexes by the silica matrix.
- Full Text:
- Date Issued: 2015
- Authors: Fashina, Adedayo , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189708 , vital:44924 , xlink:href="https://doi.org/10.1016/j.saa.2014.08.062"
- Description: This work presents the synthesis and characterization of a new zinc phthalocyanine complex tetrasubstituted with 3-carboxyphenoxy in the peripheral position. The photophysical properties of the new complex are compared with those of phthalocyanines tetra substituted with 3-carboxyphenoxy or 4- carboxyphenoxy at non-peripheral positions. Three phthalocyanine complexes were encapsulated within silica matrix to form a core shell and the hybrid nanoparticles particles obtained were spherical and mono dispersed. When encapsulated within the silica shell nanoparticles, phthalocyanines showed improved triplet quantum yields and singlet oxygen quantum yields than surface grafted derivatives. The improvements observed could be attributed to the protection provided for the phthalocyanine complexes by the silica matrix.
- Full Text:
- Date Issued: 2015
A critical assessment of economic policies and their impact on entrepreneurship development in South Africa: a case of Khayelitsha Township in Cape Town
- Oduwole, Olusola https://orcid.org/0000-0002-1563-7392
- Authors: Oduwole, Olusola https://orcid.org/0000-0002-1563-7392
- Date: 2015
- Subjects: Entrepreneurship , Economic policy , Economic development -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26302 , vital:65236
- Description: The complexity of the South African society due to past systematic exclusion of some communities from economic activities resulted in the triple challenge of poverty, inequality and unemployment. Although various economic policies had been developed since the advent of the democratic dispensation in 1994, these policies focused on levelling the economic environment, poverty alleviation and massive social security system. However, despite all the interventions, South Africa remains one of the most unequal societies in the world. This is profiled by the mushrooming of informal settlements around cities with job seekers and frequent protests by people who are impatient to experience improvement in their quality of life and who feel cheated out of their social contract. Advocacy from the governing party’s tripartite alliance towards a developmental state had placed more obligations on the government. This requires deliberate interventions through policies implementation to improve or at best alleviate the well-being of the citizenry. A survey conducted in the township of Khayelitsha to assess the impact of such economic policies on the development of entrepreneurship. Khayelitsha is one of South Africa’s largest townships, an informal settlement profiled by unemployment, poor infrastructure and unavailability of basic services. The study explored the entrepreneurial perception, start-up barriers, entrepreneurship climate, and general cultural factors relating to the environment of entrepreneurship development. The results reveal that despite the various economic policies, high level of unwillingness of citizens towards entrepreneurial activity and business venture is rife notwithstanding the high level of unemployment and poverty. The antidote to these challenges would be a rapid entrepreneurship drive among people most affected that would cause them to mind their own business” and become “masters of their own destinies. Given the complexity and massiveness of the challenges, the conclusion shows that a pragmatic solution is required. Therefore, the emancipation of entrepreneurship development in South Africa townships needs attention. The recommended solution is a pragmatic and innovative strategy based on the acronyms NEEDS HELP which stand for Neighbourhood Enhancement and Environmental Development Strategy and Holistic Entrepreneurial Lifestyle Programme. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
- Authors: Oduwole, Olusola https://orcid.org/0000-0002-1563-7392
- Date: 2015
- Subjects: Entrepreneurship , Economic policy , Economic development -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26302 , vital:65236
- Description: The complexity of the South African society due to past systematic exclusion of some communities from economic activities resulted in the triple challenge of poverty, inequality and unemployment. Although various economic policies had been developed since the advent of the democratic dispensation in 1994, these policies focused on levelling the economic environment, poverty alleviation and massive social security system. However, despite all the interventions, South Africa remains one of the most unequal societies in the world. This is profiled by the mushrooming of informal settlements around cities with job seekers and frequent protests by people who are impatient to experience improvement in their quality of life and who feel cheated out of their social contract. Advocacy from the governing party’s tripartite alliance towards a developmental state had placed more obligations on the government. This requires deliberate interventions through policies implementation to improve or at best alleviate the well-being of the citizenry. A survey conducted in the township of Khayelitsha to assess the impact of such economic policies on the development of entrepreneurship. Khayelitsha is one of South Africa’s largest townships, an informal settlement profiled by unemployment, poor infrastructure and unavailability of basic services. The study explored the entrepreneurial perception, start-up barriers, entrepreneurship climate, and general cultural factors relating to the environment of entrepreneurship development. The results reveal that despite the various economic policies, high level of unwillingness of citizens towards entrepreneurial activity and business venture is rife notwithstanding the high level of unemployment and poverty. The antidote to these challenges would be a rapid entrepreneurship drive among people most affected that would cause them to mind their own business” and become “masters of their own destinies. Given the complexity and massiveness of the challenges, the conclusion shows that a pragmatic solution is required. Therefore, the emancipation of entrepreneurship development in South Africa townships needs attention. The recommended solution is a pragmatic and innovative strategy based on the acronyms NEEDS HELP which stand for Neighbourhood Enhancement and Environmental Development Strategy and Holistic Entrepreneurial Lifestyle Programme. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
Agathis bishopi (Hymenoptera: Braconidae) as a potential tool for detecting oranges infested with Thaumatotibia leucotreta (Lepidoptera: Tortricidae)
- Zimba, Kennedy J, Hill, Martin P, Moore, Sean D, Heshula, Unathi
- Authors: Zimba, Kennedy J , Hill, Martin P , Moore, Sean D , Heshula, Unathi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423955 , vital:72108 , xlink:href="https://doi.org/10.1007/s10905-015-9526-0"
- Description: In South Africa, Thaumatotibia leucotreta is a key pest of citrus impacting its production and trade. Detection of newly infested fruit by visual inspection is challenging and poses a risk of packing infested with healthy fruit for export. Agathis bishopi is a larval endoparasitoid of T. leucotreta, attacking early larval instars. Understanding how A. bishopi parasitoids locate fruit infested with their host is of interest for developing an efficient detector for T. leucotreta infested fruit. The response of female adult A. bishopi parasitoids to olfactory and visual cues associated with T. leucotreta infested fruit were evaluated using a Y-tube olfactometer and flight tunnel. Agathis bishopi parasitoids were strongly attracted to infested fruit over healthy fruit, either when only olfactory or combinations of visual and olfactory cues were offered. Among the four synthetic compounds tested, D-limonene and ocimene elicited a strong attraction to parasitoids with response rates of 92 % and 72 % respectively. A blend of four synthetic compounds simulating T. leucotreta infested fruit odour equally elicited strong attraction to parasitoids (84 % response rate). Attraction of parasitoids to infested fruit cues was heightened by prior experience, suggesting the occurrence of associative learning. Results from this study indicate that A. bishopi parasitoids mainly rely on olfactory cues in host habitat location and that D-limonene and ocimene are the major attractants in infested fruit volatiles. These findings and the potential for manipulating A. bishopi for detection of infested fruit in the packhouse are discussed.
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy J , Hill, Martin P , Moore, Sean D , Heshula, Unathi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423955 , vital:72108 , xlink:href="https://doi.org/10.1007/s10905-015-9526-0"
- Description: In South Africa, Thaumatotibia leucotreta is a key pest of citrus impacting its production and trade. Detection of newly infested fruit by visual inspection is challenging and poses a risk of packing infested with healthy fruit for export. Agathis bishopi is a larval endoparasitoid of T. leucotreta, attacking early larval instars. Understanding how A. bishopi parasitoids locate fruit infested with their host is of interest for developing an efficient detector for T. leucotreta infested fruit. The response of female adult A. bishopi parasitoids to olfactory and visual cues associated with T. leucotreta infested fruit were evaluated using a Y-tube olfactometer and flight tunnel. Agathis bishopi parasitoids were strongly attracted to infested fruit over healthy fruit, either when only olfactory or combinations of visual and olfactory cues were offered. Among the four synthetic compounds tested, D-limonene and ocimene elicited a strong attraction to parasitoids with response rates of 92 % and 72 % respectively. A blend of four synthetic compounds simulating T. leucotreta infested fruit odour equally elicited strong attraction to parasitoids (84 % response rate). Attraction of parasitoids to infested fruit cues was heightened by prior experience, suggesting the occurrence of associative learning. Results from this study indicate that A. bishopi parasitoids mainly rely on olfactory cues in host habitat location and that D-limonene and ocimene are the major attractants in infested fruit volatiles. These findings and the potential for manipulating A. bishopi for detection of infested fruit in the packhouse are discussed.
- Full Text:
- Date Issued: 2015
Agathis bishopi, a larval parasitoid of false codling moth Thaumatotibia leucotreta: laboratory rearing and effect of adult food on parasitism and longevity
- Zimba, Kennedy J, Moore, Sean D, Heshula, Lelethu U P, Hill, Martin P
- Authors: Zimba, Kennedy J , Moore, Sean D , Heshula, Lelethu U P , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406985 , vital:70328 , xlink:href="https://hdl.handle.net/10520/EJC185849"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae) is a koinobiont larval endoparasitoid of false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of economic importance on citrus in South Africa. In the field Agathis bishopi was found to parasitise up to 34 % of FCM larvae in fruit, reflecting reasonable biocontrol potential. Improving the rearing of A. bishopi would therefore complement the existing biocontrol strategies for FCM. In several parasitic wasps, sugar concentration and feeding duration has been shown to influence parasitism and longevity. However, their effect on parasitism and longevity of A. bishopi is unknown. In the present study a rearing protocol for A. bishopi is described, including evaluation of the effects of honey concentration on parasitoid longevity. On average, 18.2%of FCM larvae in rearing containers were parasitised under the rearing protocol described. Cotton wool, instead of paper towelling, as honey carrier for feeding parasitoids in rearing containers significantly increased parasitism and yield of offspring. Furthermore, longevity significantly increased with higher concentrations of honey. Maximum lifespan duration for male and female parasitoids was achieved when parasitoids were fed on 36 % (w/v) honey. Results from this study indicate that A. bishopi requires a sufficient concentration of sugar, coupled with frequent and prolonged feeding on a cotton wool substrate, in order to achieve maximum parasitism and longevity. Such information provides a basis for optimising mass-rearing and longevity of A. bishopi and parasitism of FCM in orchards.
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy J , Moore, Sean D , Heshula, Lelethu U P , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406985 , vital:70328 , xlink:href="https://hdl.handle.net/10520/EJC185849"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae) is a koinobiont larval endoparasitoid of false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of economic importance on citrus in South Africa. In the field Agathis bishopi was found to parasitise up to 34 % of FCM larvae in fruit, reflecting reasonable biocontrol potential. Improving the rearing of A. bishopi would therefore complement the existing biocontrol strategies for FCM. In several parasitic wasps, sugar concentration and feeding duration has been shown to influence parasitism and longevity. However, their effect on parasitism and longevity of A. bishopi is unknown. In the present study a rearing protocol for A. bishopi is described, including evaluation of the effects of honey concentration on parasitoid longevity. On average, 18.2%of FCM larvae in rearing containers were parasitised under the rearing protocol described. Cotton wool, instead of paper towelling, as honey carrier for feeding parasitoids in rearing containers significantly increased parasitism and yield of offspring. Furthermore, longevity significantly increased with higher concentrations of honey. Maximum lifespan duration for male and female parasitoids was achieved when parasitoids were fed on 36 % (w/v) honey. Results from this study indicate that A. bishopi requires a sufficient concentration of sugar, coupled with frequent and prolonged feeding on a cotton wool substrate, in order to achieve maximum parasitism and longevity. Such information provides a basis for optimising mass-rearing and longevity of A. bishopi and parasitism of FCM in orchards.
- Full Text:
- Date Issued: 2015
Amoxicillin removal from aqueous media using multi-walled carbon nanotubes
- Mohammadi, Ali, Kazemipour, Maryam, Walker, Roderick B, Ansari, Mehdi
- Authors: Mohammadi, Ali , Kazemipour, Maryam , Walker, Roderick B , Ansari, Mehdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183861 , vital:44076 , xlink:href="https://doi.org/10.1080/1536383X.2013.866944"
- Description: Multi-walled carbon nanotubes (MWCNT) were used to separate amoxicillin from aqueous media. The parameters affecting amoxicillin adsorption such as pH, temperature, time, interferences of similar molecules, and the amount of adsorbent used were studied. Amoxicillin adsorption using MWCNT was compared to that using Fullerene C60 and activated carbon (AC). The adsorption efficiency of 0.1 and 0.2 g of MWCNT using in a continuous mode were 86.5% and 87.9%, respectively. Evaluation of the adsorbent capacity showed that each gram of MWCNT can absorb 22.9 mg amoxicillin. The effect of pH was studied over the range 2–8 and revealed that adsorption of the amoxicillin at the initial pH of 4.6 was more effective than any other pH. The adsorption of amoxicillin on MWCNT was much greater than Fullerene C60 and AC. Adsorption data showed that they were best fitted to the Langmuir isotherm.
- Full Text:
- Date Issued: 2015
- Authors: Mohammadi, Ali , Kazemipour, Maryam , Walker, Roderick B , Ansari, Mehdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183861 , vital:44076 , xlink:href="https://doi.org/10.1080/1536383X.2013.866944"
- Description: Multi-walled carbon nanotubes (MWCNT) were used to separate amoxicillin from aqueous media. The parameters affecting amoxicillin adsorption such as pH, temperature, time, interferences of similar molecules, and the amount of adsorbent used were studied. Amoxicillin adsorption using MWCNT was compared to that using Fullerene C60 and activated carbon (AC). The adsorption efficiency of 0.1 and 0.2 g of MWCNT using in a continuous mode were 86.5% and 87.9%, respectively. Evaluation of the adsorbent capacity showed that each gram of MWCNT can absorb 22.9 mg amoxicillin. The effect of pH was studied over the range 2–8 and revealed that adsorption of the amoxicillin at the initial pH of 4.6 was more effective than any other pH. The adsorption of amoxicillin on MWCNT was much greater than Fullerene C60 and AC. Adsorption data showed that they were best fitted to the Langmuir isotherm.
- Full Text:
- Date Issued: 2015
An analysis of ethics and governance practices in the public sector: United Nations and African Union perspectives
- Authors: Shindika, Emmanuel Selemani
- Date: 2015
- Subjects: United Nations , African Union , Public administration -- Moral and ethical aspects
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26164 , vital:64946
- Description: Recent studies highlight the importance of improving governance and ethics in public entities, especially in Africa. However, doing so requires an understanding on what forms governance and ethics in public institutions, particularly at a national level. Such considerations necessitates that some focus on continental and world institutions, such as, the African Union and the United Nations. These institutions have been in existence for a number of years with mandates of improving member states governance and ethics, as well as, service delivery to the public. As such, this research primarily focuses on understanding the roles played by the AU and the UN in shaping governance and ethics to member states, as well as, of its employees. The focus of this inquiry was to understand individual narratives about how working for public institutions on a daily to day basis influences governance and ethics understanding and application. Therefore, in order to properly analyse the narratives from respondents, the study applied an inductive and qualitative approach in order to explore how the AU and UN systems influence governance and ethics for member s states and employees. Data was collected through semi structured interviews with UN and AU officials, as well as public servants of member states for those organisations. The study made use of a thematic analyses method of interpreting data. A total of six major themes emerged, they are as follows: ethics a part in governance; effectiveness of AU and UN systems; disciplinary role; ethical guidelines and standards influence on public sector; member states adherence to the UN/AU ethical conduct; and implementation gaps in ethical guidelines within member states. Interviews were conducted in four countries namely; South Africa, Tanzania, Mauritius and Botswana. Findings from the study pointed that the AU and UN systems have loopholes in dealing with issues of governance and ethics. Moreover, member states respondents also pointed to the loopholes in those two organisations. The research suggests that member states should tighten their public entities ethical compliance assessments and follow suggestions from the UN and AU. Final recommendations and suggestions for further research are provided. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
- Authors: Shindika, Emmanuel Selemani
- Date: 2015
- Subjects: United Nations , African Union , Public administration -- Moral and ethical aspects
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26164 , vital:64946
- Description: Recent studies highlight the importance of improving governance and ethics in public entities, especially in Africa. However, doing so requires an understanding on what forms governance and ethics in public institutions, particularly at a national level. Such considerations necessitates that some focus on continental and world institutions, such as, the African Union and the United Nations. These institutions have been in existence for a number of years with mandates of improving member states governance and ethics, as well as, service delivery to the public. As such, this research primarily focuses on understanding the roles played by the AU and the UN in shaping governance and ethics to member states, as well as, of its employees. The focus of this inquiry was to understand individual narratives about how working for public institutions on a daily to day basis influences governance and ethics understanding and application. Therefore, in order to properly analyse the narratives from respondents, the study applied an inductive and qualitative approach in order to explore how the AU and UN systems influence governance and ethics for member s states and employees. Data was collected through semi structured interviews with UN and AU officials, as well as public servants of member states for those organisations. The study made use of a thematic analyses method of interpreting data. A total of six major themes emerged, they are as follows: ethics a part in governance; effectiveness of AU and UN systems; disciplinary role; ethical guidelines and standards influence on public sector; member states adherence to the UN/AU ethical conduct; and implementation gaps in ethical guidelines within member states. Interviews were conducted in four countries namely; South Africa, Tanzania, Mauritius and Botswana. Findings from the study pointed that the AU and UN systems have loopholes in dealing with issues of governance and ethics. Moreover, member states respondents also pointed to the loopholes in those two organisations. The research suggests that member states should tighten their public entities ethical compliance assessments and follow suggestions from the UN and AU. Final recommendations and suggestions for further research are provided. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
An analysis of schooling outcomes in the Eastern Cape, using production function approach
- Authors: Ncanywa, Thobeka
- Date: 2015
- Subjects: Education -- Economic aspects , Production functions (Economic theory) , School management and organization
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26570 , vital:65656
- Description: This study analysed the schooling outcomes of the Eastern Cape Department of Basic Education in the period heading into the second decade of democracy. The main objective of the thesis is to discover what constitutes the education production function of the Eastern Cape schooling system. In an attempt to reach this objective, the study adopted an education production function approach to answer the questions of what constitute the Eastern Cape education production function, what the effects are of the Dinaledi policy interventions on learner performance and the effects of district size on schooling outcomes. The main focus of the constituents of the production function is on the level of the former Bantustan penalty and Department of Education and Training (DET) penalty in relation to former White schools; as well as the quality of educators in the province. The Ordinary Least Squares (OLS) and quantile regressions were used to analyse the data and the Annual National Assessment (ANA) represented schooling outcomes and was estimated against school, educator and community characteristics. The results indicated a strong relationship between schooling outcomes and the school inputs that were used in the study. The effects of the Dinaledi intervention programme were analysed using the grade 12 panel data for the period from 2008 to 2013, where event dropout rates represented schooling outcomes. The findings that emerged from this study indicated that this programme provides a model that can improve the Eastern Cape schooling outcomes. The effects of district size on schooling outcomes were analysed with the regression discontinuity design technique and this revealed that district sizes have an impact on schooling outcomes. Overall, the results suggested that White schools perform better than their counterparts; that placing schools in quintiles is a good policy intervention; and that educator quality is associated with schooling outcomes. The key findings from this research were the continuing existence of the apartheid legacy in Black schools; poor educator quality; an inappropriate language of instruction; gender inequalities in performance and an uneven distribution of schools in districts. The recommendations for this research are to pay more attention to the improvement of educator quality in terms of educator qualifications, training and remuneration; implement a programme like the Dinaledi programme to all schools, as it provides resources to schools; and enforce the district size as informed by the district act so as to improve the support that district officials give to schools. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
- Authors: Ncanywa, Thobeka
- Date: 2015
- Subjects: Education -- Economic aspects , Production functions (Economic theory) , School management and organization
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26570 , vital:65656
- Description: This study analysed the schooling outcomes of the Eastern Cape Department of Basic Education in the period heading into the second decade of democracy. The main objective of the thesis is to discover what constitutes the education production function of the Eastern Cape schooling system. In an attempt to reach this objective, the study adopted an education production function approach to answer the questions of what constitute the Eastern Cape education production function, what the effects are of the Dinaledi policy interventions on learner performance and the effects of district size on schooling outcomes. The main focus of the constituents of the production function is on the level of the former Bantustan penalty and Department of Education and Training (DET) penalty in relation to former White schools; as well as the quality of educators in the province. The Ordinary Least Squares (OLS) and quantile regressions were used to analyse the data and the Annual National Assessment (ANA) represented schooling outcomes and was estimated against school, educator and community characteristics. The results indicated a strong relationship between schooling outcomes and the school inputs that were used in the study. The effects of the Dinaledi intervention programme were analysed using the grade 12 panel data for the period from 2008 to 2013, where event dropout rates represented schooling outcomes. The findings that emerged from this study indicated that this programme provides a model that can improve the Eastern Cape schooling outcomes. The effects of district size on schooling outcomes were analysed with the regression discontinuity design technique and this revealed that district sizes have an impact on schooling outcomes. Overall, the results suggested that White schools perform better than their counterparts; that placing schools in quintiles is a good policy intervention; and that educator quality is associated with schooling outcomes. The key findings from this research were the continuing existence of the apartheid legacy in Black schools; poor educator quality; an inappropriate language of instruction; gender inequalities in performance and an uneven distribution of schools in districts. The recommendations for this research are to pay more attention to the improvement of educator quality in terms of educator qualifications, training and remuneration; implement a programme like the Dinaledi programme to all schools, as it provides resources to schools; and enforce the district size as informed by the district act so as to improve the support that district officials give to schools. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
An investigation of source rocks and depositional environments on acid mine drainage in South African coal mines: a comparison of the main Karoo basin and sub-basins.
- Authors: Ncube, Lindani
- Date: 2015
- Subjects: Mine drainage -- Environmental aspects -- South Africa , Coal mines and mining -- Environmental aspects -- South Africa , Acid mine drainage -- Environmental aspects -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19556 , vital:43139
- Description: The coal deposits have been and continue to be the primary source of energy in South Africa. The continuous use of coal presents many challenges that includes genesis of acid mine drainage (AMD) which is as a result of the oxidation of predominant pyrite (FeS2) and other sulphides. The aim of this study was to investigate the role of source rocks and their depositional environments on AMD generation in South African coal mine environments. Five collieries from five coalfields were selected as case studies: Brandspruit in the Highveld, Vaalkrantz in the Vryheid, the Elitheni in the Molteno-Indwe, the Arnot in the Witbank and the Malatleng Exploration Project in the Waterberg Coalfields. Brandspruit, Vaalkrantz and Elitheni Collieries are located in the Main Karoo Basin, while the Witbank and the Waterberg Coalfields are located in Sub-Basins. The study investigated a variety of indices such as palaeo-depositional environments, mineral assemblages, geochemical signatures, water quality parameters, acid base accounting (ABA) and water leach tests for the coal and associated non-coal strata. An effort was made to establish the relationship between the mineralogy of the studied lithologies and the associated water quality. The study resulted in delineation of detrital and diagenetic rock components and interpretation of source area of rock types and the origin and timing of diagenetic alterations. Sandstone units are prevalent, except in the Waterberg Coalfield where mudstones are prevalent. Classifications of the mineralogical composition with descriptive adjectives yield the rock names arkose to sub-arkose categories in the Main Karoo Basin, and sub-arenites to quartz arenites in the Sub-Basins with the sandstones of recycled origin. Further, the sandstones of the Main Karoo Basin are of mixed provenance whilst those of Sub-Basins represent cratonic interior provenance. Sandstone from the Main Karoo Basin generally exhibit high concentrations of feldspars, which favour either high relief, arid or arctic climates with less chemical weathering at the source area. The presence of glauconite in sediments of the Main Karoo Basin attests to a marine continental shelf depositional environment. Sediments of the Main Karoo Basin have high contents of tadpole-shaped pyrite in coal and non-coal strata as compared to sediments of the Sub-Basins. The observed pyrite is ascribed to early diagenetic origin, and is closely related to the generation of acid mining drainage. The sediments have experienced an involved sequence of diagenetic alterations. The alterations considered to be typical for sandstones in the Main Karoo Basin are calcite cementation, feldspar dissolution, kaolinite infilling, pyrite grain coatings, albitization and pressure solution; whereas, quartz overgrowth and clay matrix filling are characteristics of sediments of Sub-Basins. The sequence and distribution of these alterations are related to the source mineral composition, depositional environment, stratigraphic relationships and burial history of the sediments. A direct link exists among the depositional environments, the mineral assemblages and the geochemical compositions of the lithologies. SiO2 is the dominant major oxide and is abundant in coals from coalfields located in the Sub-Basins. Si, Al, Fe, Ca, S, Mg, K and Na show strong association with their discrete minerals. The sandstones are substantially enriched in elements that are chemically immobile and associated with terrigenous influx, such as SiO2, Al2O3, and TiO2. The observed high contents of SiO2 are probably due to source rocks and silicification. SiO2, Al2O3 and TiO2 are related to clay and heavy minerals, with elevated Fe2O3 (Total) content in sediments of the Main Karoo Basin ascribed to sulphidization. Sediments from the Main Karoo Basin are enriched in both Na2O and K2O due to albitization and muscovitization. Substantial concentrations of Ba, Rb and Zr are in accordance to the high amount of phyllosilicates and heavy minerals. Muscovitization contributes to the correlation of Rb and Ba with K2O. The shales are substantially depleted in SiO2, CaO, MgO, Na2O, K2O, TiO2 and Fe2O3 due to weathering and diagenetic alteration, but are enriched in Al2O3 and P2O5. The ABA test clearly indicates that sandstones from the Main Karoo Basin have a potential of generating AMD as they contain sufficient pyrite to generate acid, with the final pH values of the samples turning acidic upon complete oxidation of pyrite. On the contrary, sediments of SubBasins contain sufficient calcite that serves to limit the amount of acid generation. Both sandstone and coal from collieries representing the Main Karoo Basin are characterised by elevated contents of S percent in comparison to coal from collieries representing the Sub-Basins. In general, the quality of water is as a result of a combination of complex geochemical interactions that involves various ions from different sources. Water leaching test shows that the leachates have varied chemical compositions with pH values in the range of 4.5-9 for the sandstone, and 2– 8.9 for the coal leachates. Variations in the pH values are attributed to regional phenomena controlled by the mineralogical and hydrological environments. Furthermore, the variation in pH is ascribed to the presence of acid forming pyrite and acid neutralizing carbonate minerals that are highly reactive in the mining environment. Elements Na, Ca, Mg and K occur in non-compliant concentrations in both coal and non-coal leachates indicating their abundance in all of the lithologies. Na enrichment in the lithologies is associated with albite, clay minerals and Al-Ksulphate coatings. Elements Fe, Al, Cd and Pb are easily leached from the lithologies. According to the equilibrium model, gibbsite, cuprite, diaspore and boehmite are the supersaturated minerals in the lithologies. Influencing factors such as the mineralogical composition of rocks are reflected in the wide variation of pH, TDS, EC and the ion concentrations of the studied water samples. The pH of the studied areas is neutral to alkaline. High levels of TDS and EC are observed in the Brandspruit Colliery, which is due to dissolution of soluble salts from the rock sequence that the water passes through. The anion chemistry shows the dominance of SO4 2- in the surface and groundwater of Brandspruit, Vaalkrantz and Elitheni Collieries, whereas HCO3 - dominates in the Arnot Colliery. SO4 2- is ascribed to the oxidative weathering of pyrites. Cldominates in groundwater from the Arnot Colliery and the Waterberg Coalfield. The cation chemistry is dominated by Na+ in the surface and groundwater of the Brandspruit, Vaalkrantz and Elitheni Collieries. Mg2+ dominates in groundwater from the Arnot Colliery, while K+ dominates in the Waterberg Coalfield. Fe is highly enriched in water from the Brandspruit Colliery, and is linked to the oxidation of pyrite. Carbonates are the supersaturated minerals in the Sub-Basins whilst sulphates are supersaturated in the Main Karoo Basin. The research shows that variations in regional mineral distribution is a result of a palaeo-deposition environment that was of marine nature for the coal sequence in the Main Karoo Basin and of fresh water for the coal sequence in Sub-Basins. A direct link therefore exists between depositional environments, mineral assemblages and whole rock geochemistry. It can be concluded that AMD is directly linked to pyrite and other sulphides, the coal mines located in the Main Karoo Basin have the possibility to deteriorate surface- and ground-water quality and to generate AMD during the mining processes; coal miners need to seriously consider applying environmental protection measures when mining coal in the Main Karoo Basin. Whereas, coal mining in the Sub-Basins has low possibility of generating AMD and pollution. , Thesis (PhD) (Geology) -- University of Fort Hare, 2015
- Full Text:
- Date Issued: 2015
- Authors: Ncube, Lindani
- Date: 2015
- Subjects: Mine drainage -- Environmental aspects -- South Africa , Coal mines and mining -- Environmental aspects -- South Africa , Acid mine drainage -- Environmental aspects -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19556 , vital:43139
- Description: The coal deposits have been and continue to be the primary source of energy in South Africa. The continuous use of coal presents many challenges that includes genesis of acid mine drainage (AMD) which is as a result of the oxidation of predominant pyrite (FeS2) and other sulphides. The aim of this study was to investigate the role of source rocks and their depositional environments on AMD generation in South African coal mine environments. Five collieries from five coalfields were selected as case studies: Brandspruit in the Highveld, Vaalkrantz in the Vryheid, the Elitheni in the Molteno-Indwe, the Arnot in the Witbank and the Malatleng Exploration Project in the Waterberg Coalfields. Brandspruit, Vaalkrantz and Elitheni Collieries are located in the Main Karoo Basin, while the Witbank and the Waterberg Coalfields are located in Sub-Basins. The study investigated a variety of indices such as palaeo-depositional environments, mineral assemblages, geochemical signatures, water quality parameters, acid base accounting (ABA) and water leach tests for the coal and associated non-coal strata. An effort was made to establish the relationship between the mineralogy of the studied lithologies and the associated water quality. The study resulted in delineation of detrital and diagenetic rock components and interpretation of source area of rock types and the origin and timing of diagenetic alterations. Sandstone units are prevalent, except in the Waterberg Coalfield where mudstones are prevalent. Classifications of the mineralogical composition with descriptive adjectives yield the rock names arkose to sub-arkose categories in the Main Karoo Basin, and sub-arenites to quartz arenites in the Sub-Basins with the sandstones of recycled origin. Further, the sandstones of the Main Karoo Basin are of mixed provenance whilst those of Sub-Basins represent cratonic interior provenance. Sandstone from the Main Karoo Basin generally exhibit high concentrations of feldspars, which favour either high relief, arid or arctic climates with less chemical weathering at the source area. The presence of glauconite in sediments of the Main Karoo Basin attests to a marine continental shelf depositional environment. Sediments of the Main Karoo Basin have high contents of tadpole-shaped pyrite in coal and non-coal strata as compared to sediments of the Sub-Basins. The observed pyrite is ascribed to early diagenetic origin, and is closely related to the generation of acid mining drainage. The sediments have experienced an involved sequence of diagenetic alterations. The alterations considered to be typical for sandstones in the Main Karoo Basin are calcite cementation, feldspar dissolution, kaolinite infilling, pyrite grain coatings, albitization and pressure solution; whereas, quartz overgrowth and clay matrix filling are characteristics of sediments of Sub-Basins. The sequence and distribution of these alterations are related to the source mineral composition, depositional environment, stratigraphic relationships and burial history of the sediments. A direct link exists among the depositional environments, the mineral assemblages and the geochemical compositions of the lithologies. SiO2 is the dominant major oxide and is abundant in coals from coalfields located in the Sub-Basins. Si, Al, Fe, Ca, S, Mg, K and Na show strong association with their discrete minerals. The sandstones are substantially enriched in elements that are chemically immobile and associated with terrigenous influx, such as SiO2, Al2O3, and TiO2. The observed high contents of SiO2 are probably due to source rocks and silicification. SiO2, Al2O3 and TiO2 are related to clay and heavy minerals, with elevated Fe2O3 (Total) content in sediments of the Main Karoo Basin ascribed to sulphidization. Sediments from the Main Karoo Basin are enriched in both Na2O and K2O due to albitization and muscovitization. Substantial concentrations of Ba, Rb and Zr are in accordance to the high amount of phyllosilicates and heavy minerals. Muscovitization contributes to the correlation of Rb and Ba with K2O. The shales are substantially depleted in SiO2, CaO, MgO, Na2O, K2O, TiO2 and Fe2O3 due to weathering and diagenetic alteration, but are enriched in Al2O3 and P2O5. The ABA test clearly indicates that sandstones from the Main Karoo Basin have a potential of generating AMD as they contain sufficient pyrite to generate acid, with the final pH values of the samples turning acidic upon complete oxidation of pyrite. On the contrary, sediments of SubBasins contain sufficient calcite that serves to limit the amount of acid generation. Both sandstone and coal from collieries representing the Main Karoo Basin are characterised by elevated contents of S percent in comparison to coal from collieries representing the Sub-Basins. In general, the quality of water is as a result of a combination of complex geochemical interactions that involves various ions from different sources. Water leaching test shows that the leachates have varied chemical compositions with pH values in the range of 4.5-9 for the sandstone, and 2– 8.9 for the coal leachates. Variations in the pH values are attributed to regional phenomena controlled by the mineralogical and hydrological environments. Furthermore, the variation in pH is ascribed to the presence of acid forming pyrite and acid neutralizing carbonate minerals that are highly reactive in the mining environment. Elements Na, Ca, Mg and K occur in non-compliant concentrations in both coal and non-coal leachates indicating their abundance in all of the lithologies. Na enrichment in the lithologies is associated with albite, clay minerals and Al-Ksulphate coatings. Elements Fe, Al, Cd and Pb are easily leached from the lithologies. According to the equilibrium model, gibbsite, cuprite, diaspore and boehmite are the supersaturated minerals in the lithologies. Influencing factors such as the mineralogical composition of rocks are reflected in the wide variation of pH, TDS, EC and the ion concentrations of the studied water samples. The pH of the studied areas is neutral to alkaline. High levels of TDS and EC are observed in the Brandspruit Colliery, which is due to dissolution of soluble salts from the rock sequence that the water passes through. The anion chemistry shows the dominance of SO4 2- in the surface and groundwater of Brandspruit, Vaalkrantz and Elitheni Collieries, whereas HCO3 - dominates in the Arnot Colliery. SO4 2- is ascribed to the oxidative weathering of pyrites. Cldominates in groundwater from the Arnot Colliery and the Waterberg Coalfield. The cation chemistry is dominated by Na+ in the surface and groundwater of the Brandspruit, Vaalkrantz and Elitheni Collieries. Mg2+ dominates in groundwater from the Arnot Colliery, while K+ dominates in the Waterberg Coalfield. Fe is highly enriched in water from the Brandspruit Colliery, and is linked to the oxidation of pyrite. Carbonates are the supersaturated minerals in the Sub-Basins whilst sulphates are supersaturated in the Main Karoo Basin. The research shows that variations in regional mineral distribution is a result of a palaeo-deposition environment that was of marine nature for the coal sequence in the Main Karoo Basin and of fresh water for the coal sequence in Sub-Basins. A direct link therefore exists between depositional environments, mineral assemblages and whole rock geochemistry. It can be concluded that AMD is directly linked to pyrite and other sulphides, the coal mines located in the Main Karoo Basin have the possibility to deteriorate surface- and ground-water quality and to generate AMD during the mining processes; coal miners need to seriously consider applying environmental protection measures when mining coal in the Main Karoo Basin. Whereas, coal mining in the Sub-Basins has low possibility of generating AMD and pollution. , Thesis (PhD) (Geology) -- University of Fort Hare, 2015
- Full Text:
- Date Issued: 2015
Assessing public administration implications of the use and disposal of agro-chemicals in A2 farms in Zimbabwe : a case study of Chirumhanzu District
- Authors: Matunhu, Viola
- Date: 2015
- Subjects: Agricultural chemicals , Hazardous waste treatment facilities , Pesticide waste
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26481 , vital:65471
- Description: This study is concerned with use and disposal of agro-chemical in A2 farms in Zimbabwe with specific reference to Chirumhanzu District. The study is located in the field of public administration. A transformational mixed research design was employed in the collection, analysis and interpretation of the field data. The study involved farm employees in 21 A2 farms that use agro-chemicals to enhance farm productivity. Non probability sampling techniques were employed to select the participating farms. Interviews, questionnaires, literature search, and observation where the main data collection instruments. A total of 150 purposively selected employees drawn from 21 participating farms participated in the study. The findings of this empirical study, which uses the terms I, the researcher, and the study interchangeably, were that there is poor use and management of agro-chemicals in the area. Most farm employees do not adhere to instructions on use and disposal of the chemicals and there is a weak monitoring and evaluation of the use and disposal of agro-chemicals on the farms. Yet, most of these chemicals are carcinogens. Farm employees need to be trained on personal and public health implications of poor management of agro-chemicals. Labels on containers that store chemicals need to be written in both English and vernacular, which is not the case in the district. Labels on most of the chemicals on the farms studied are written in English and technical terms are used. Although, most of the employees on the farms are literate, they find it difficult to understand the jargon on labels. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
- Authors: Matunhu, Viola
- Date: 2015
- Subjects: Agricultural chemicals , Hazardous waste treatment facilities , Pesticide waste
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26481 , vital:65471
- Description: This study is concerned with use and disposal of agro-chemical in A2 farms in Zimbabwe with specific reference to Chirumhanzu District. The study is located in the field of public administration. A transformational mixed research design was employed in the collection, analysis and interpretation of the field data. The study involved farm employees in 21 A2 farms that use agro-chemicals to enhance farm productivity. Non probability sampling techniques were employed to select the participating farms. Interviews, questionnaires, literature search, and observation where the main data collection instruments. A total of 150 purposively selected employees drawn from 21 participating farms participated in the study. The findings of this empirical study, which uses the terms I, the researcher, and the study interchangeably, were that there is poor use and management of agro-chemicals in the area. Most farm employees do not adhere to instructions on use and disposal of the chemicals and there is a weak monitoring and evaluation of the use and disposal of agro-chemicals on the farms. Yet, most of these chemicals are carcinogens. Farm employees need to be trained on personal and public health implications of poor management of agro-chemicals. Labels on containers that store chemicals need to be written in both English and vernacular, which is not the case in the district. Labels on most of the chemicals on the farms studied are written in English and technical terms are used. Although, most of the employees on the farms are literate, they find it difficult to understand the jargon on labels. , Thesis (PhD) -- Faculty of Management and Commerce, 2015
- Full Text:
- Date Issued: 2015
Baculovirus-based strategies for the management of insect pests: a focus on development and application in South Africa
- Knox, Caroline M, Moore, Sean D, Luke, Garry, Hill, Martin P
- Authors: Knox, Caroline M , Moore, Sean D , Luke, Garry , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416829 , vital:71389 , xlink:href="https://doi.org/10.1080/09583157.2014.949222"
- Description: There is growing concern among governments, scientists, agricultural practitioners and the general public regarding the negative implications of widespread synthetic chemical pesticide application for the control of crop pests. As a result, baculovirus biopesticides are gaining popularity as components of integrated pest management (IPM) programmes in many countries despite several disadvantages related to slow speed of kill, limited host range and complex large scale production. In South Africa, baculoviruses are incorporated into IPM programmes for the control of crop pests in the field, and recent bioprospecting has led to the characterisation of several novel isolates with the potential to be formulated as commercial products. This contribution will provide an overview of the use of baculoviruses against insect pests in South Africa, as well as research and development efforts aimed at broadening their application as biocontrol agents. Challenges faced by researchers in developmental projects as well as potential users of baculoviruses as biopesticides in the field are also discussed.
- Full Text:
- Date Issued: 2015
- Authors: Knox, Caroline M , Moore, Sean D , Luke, Garry , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416829 , vital:71389 , xlink:href="https://doi.org/10.1080/09583157.2014.949222"
- Description: There is growing concern among governments, scientists, agricultural practitioners and the general public regarding the negative implications of widespread synthetic chemical pesticide application for the control of crop pests. As a result, baculovirus biopesticides are gaining popularity as components of integrated pest management (IPM) programmes in many countries despite several disadvantages related to slow speed of kill, limited host range and complex large scale production. In South Africa, baculoviruses are incorporated into IPM programmes for the control of crop pests in the field, and recent bioprospecting has led to the characterisation of several novel isolates with the potential to be formulated as commercial products. This contribution will provide an overview of the use of baculoviruses against insect pests in South Africa, as well as research and development efforts aimed at broadening their application as biocontrol agents. Challenges faced by researchers in developmental projects as well as potential users of baculoviruses as biopesticides in the field are also discussed.
- Full Text:
- Date Issued: 2015
Beauveria and Metarhizium against false codling moth (Lepidoptera: Tortricidae): a step towards selecting isolates for potential development of a mycoinsecticide
- Coombes, Candice A, Hill, Martin P, Moore, Sean D, Dames, Joanna F, Fullard, T
- Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F , Fullard, T
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405757 , vital:70203 , xlink:href="https://hdl.handle.net/10520/EJC167505"
- Description: False codling moth, Thaumatotibia leucotreta Meyrick (1912) (Lepidoptera: Tortricidae), can cause both pre- and post-harvest damage to citrus fruit. Not only can this result in reduced crop yield, but more importantly because of the moth's endemism to sub-Saharan Africa, it is classified as a phytosanitary pest by many export markets. An entire consignment of citrus may be rejected in the presence of a single moth (Moore 2012). Since the bulk of citrus fruit production in South Africa is exported, the control of T. leucotreta is critical (Citrus Growers Association, South Africa 2012). Traditionally, control has been achieved through the use of chemical insecticides; however, residue restrictions, resistance development and concerns about environmental pollution have substantially reduced the dependence on chemical pesticides in citrus. Research on T. leucotreta control has therefore focused on the use of biological organisms (e.g. parasitoids and viruses), which are used as control agents within an integrated pest management (IPM) programme in citrus. These biological control agents, however, only targeted the aboveground life stages of the pest, not the soil-dwelling life stages (late fifth instars, prepupae, pupae), which is the subject of this contribution (Moore 2012).
- Full Text:
- Date Issued: 2015
- Authors: Coombes, Candice A , Hill, Martin P , Moore, Sean D , Dames, Joanna F , Fullard, T
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405757 , vital:70203 , xlink:href="https://hdl.handle.net/10520/EJC167505"
- Description: False codling moth, Thaumatotibia leucotreta Meyrick (1912) (Lepidoptera: Tortricidae), can cause both pre- and post-harvest damage to citrus fruit. Not only can this result in reduced crop yield, but more importantly because of the moth's endemism to sub-Saharan Africa, it is classified as a phytosanitary pest by many export markets. An entire consignment of citrus may be rejected in the presence of a single moth (Moore 2012). Since the bulk of citrus fruit production in South Africa is exported, the control of T. leucotreta is critical (Citrus Growers Association, South Africa 2012). Traditionally, control has been achieved through the use of chemical insecticides; however, residue restrictions, resistance development and concerns about environmental pollution have substantially reduced the dependence on chemical pesticides in citrus. Research on T. leucotreta control has therefore focused on the use of biological organisms (e.g. parasitoids and viruses), which are used as control agents within an integrated pest management (IPM) programme in citrus. These biological control agents, however, only targeted the aboveground life stages of the pest, not the soil-dwelling life stages (late fifth instars, prepupae, pupae), which is the subject of this contribution (Moore 2012).
- Full Text:
- Date Issued: 2015
Benzimidazole or Diamide From a Reaction of Diamines and Carboxylic Acids or Acid Chlorides: Crystal Structures and Theoretical Studies
- Odame, Felix, Hosten, Eric C, Betz, Richard, Lobb, Kevin A, Tshentu, Zenixole R
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447938 , vital:74685 , xlink:href="https://pdfs.semanticscholar.org/bf5a/ce94c9436f40059793eb988e08da8ef09886.pdf"
- Description: A reaction of an acid chloride with a diamine yielded a diamide. m-Toluic acid was chlorinated to m-toluoyl chloride and subsequently reacted with 4-methyl-o-phenylenediamine in pyridine to obtain 3-methyl-N-[2-(3-methylbenzamido)phenylbenzamide (I). 2-(3-Methylphenyl)-1H-benzimidazole (II) has been obtained upon reacting o-phenylenediamine with m-toluic acid in polyphosphoric acid and toluene. The compounds have been characterized by IR, NMR, microanalyses and GC-MS. The crystal structures of the compounds have been discussed. DFT calculations of the frontier orbitals of the precursor compounds have been carried out to ascertain the groups that contribute to the HOMO and LUMO, and to study their contribution to the reactivity in the formation of the diamides and benzimidazoles. The synthesis of the amide from a diamine was seen to be favoured in the presence of a good leaving group attached to the carbonyl as in the case of acid chloride. However, the synthesis of benzimidazoles was found to be favoured in the presence of an excess of a protonating agent and high temperature.
- Full Text:
- Date Issued: 2015
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447938 , vital:74685 , xlink:href="https://pdfs.semanticscholar.org/bf5a/ce94c9436f40059793eb988e08da8ef09886.pdf"
- Description: A reaction of an acid chloride with a diamine yielded a diamide. m-Toluic acid was chlorinated to m-toluoyl chloride and subsequently reacted with 4-methyl-o-phenylenediamine in pyridine to obtain 3-methyl-N-[2-(3-methylbenzamido)phenylbenzamide (I). 2-(3-Methylphenyl)-1H-benzimidazole (II) has been obtained upon reacting o-phenylenediamine with m-toluic acid in polyphosphoric acid and toluene. The compounds have been characterized by IR, NMR, microanalyses and GC-MS. The crystal structures of the compounds have been discussed. DFT calculations of the frontier orbitals of the precursor compounds have been carried out to ascertain the groups that contribute to the HOMO and LUMO, and to study their contribution to the reactivity in the formation of the diamides and benzimidazoles. The synthesis of the amide from a diamine was seen to be favoured in the presence of a good leaving group attached to the carbonyl as in the case of acid chloride. However, the synthesis of benzimidazoles was found to be favoured in the presence of an excess of a protonating agent and high temperature.
- Full Text:
- Date Issued: 2015
Book Review Growing the next generation of researchers: A handbook for emerging researchers and their mentors, Holness, L
- Motshoane, Puleng, Muthama, Evelyn, McKenna, Sioux
- Authors: Motshoane, Puleng , Muthama, Evelyn , McKenna, Sioux
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187205 , vital:44579 , xlink:href="https://doi.org/10.14426/cristal.v3i2.56"
- Description: South Africa urgently needs more researchers (NRF, 2008; NDP, 2011). We also need a transformation in the demographics of our researchers. One indicator of this is that currently only 14% of university professors are black African, and only 2% are black African females (DHET, 2012). The Staffing South Africa's Universities Framework includes a number of initiatives to drive the process of growing the next generation of academics. For example, the nGAP project has inserted 125 new posts into the higher education system in 2015, with more to follow. This project allows for new academics to undertake postgraduate study and develop as teachers and researchers through mentorship, a reduced teaching load and so on.
- Full Text:
- Date Issued: 2015
- Authors: Motshoane, Puleng , Muthama, Evelyn , McKenna, Sioux
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187205 , vital:44579 , xlink:href="https://doi.org/10.14426/cristal.v3i2.56"
- Description: South Africa urgently needs more researchers (NRF, 2008; NDP, 2011). We also need a transformation in the demographics of our researchers. One indicator of this is that currently only 14% of university professors are black African, and only 2% are black African females (DHET, 2012). The Staffing South Africa's Universities Framework includes a number of initiatives to drive the process of growing the next generation of academics. For example, the nGAP project has inserted 125 new posts into the higher education system in 2015, with more to follow. This project allows for new academics to undertake postgraduate study and develop as teachers and researchers through mentorship, a reduced teaching load and so on.
- Full Text:
- Date Issued: 2015
Book Review: A Renegade called Simphiwe
- Authors: Magadla, Siphokazi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298595 , vital:57719 , xlink:href="https://doi.org/10.1177/0021909614533638"
- Description: A Renegade called Simphiwe is a “creative-intellectual portrait” of the public (and private) life of the musician Simphiwe Dana (p. 150). Gqola defines the book as “one writer’s engagement with the Simphiwe Dana of the South African public imagination [who]… troubles many categories of belonging in the South African public imagination in remarkable ways” (pp. 17, 32). The book comes at a poignant time as South Africa reflects on the success and challenges of the first 20 years of democracy. Fittingly, Gqola positions Dana within a long tradition of griots in Africa whose art always spoke truth to power.
- Full Text:
- Date Issued: 2015
- Authors: Magadla, Siphokazi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298595 , vital:57719 , xlink:href="https://doi.org/10.1177/0021909614533638"
- Description: A Renegade called Simphiwe is a “creative-intellectual portrait” of the public (and private) life of the musician Simphiwe Dana (p. 150). Gqola defines the book as “one writer’s engagement with the Simphiwe Dana of the South African public imagination [who]… troubles many categories of belonging in the South African public imagination in remarkable ways” (pp. 17, 32). The book comes at a poignant time as South Africa reflects on the success and challenges of the first 20 years of democracy. Fittingly, Gqola positions Dana within a long tradition of griots in Africa whose art always spoke truth to power.
- Full Text:
- Date Issued: 2015
Book Review: Global Governance and the New Wars
- Authors: Magadla, Siphokazi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298640 , vital:57723 , xlink:href="https://doi.org/10.1080/02589346.2015.1008676"
- Description: Mark Duffield's second edition of ‘Global Governance and the New Wars’ offers an important and biting critique of how different actors within the security and development discourse have adapted to the various transformations of war in the post-cold war era. In this picture drawn by Duffield, the power of states in the South continues to be eroded by an exclusionary market that is driven by the global political economy wherein state's development and security responsibilities are increasingly assumed by non-state actors (predominately constituted by Western aid agencies). Those who fall outside the bounds of the state, development and humanitarian aid agencies can be found operating in an expanding shadow economy that is also shaped by a global dynamics which make the conditions for ‘network war' possible. In this context, the lines between ‘war' and peace” are difficult to distinguish. Overall, the book paints a depressing picture on the lack of substantive changes in the livelihoods of the poor as attention has been directed to discussions about ‘new wars' or altered forms of violence that have characterized the post-cold war era. The book unforgivingly exposes the failures of the discursive changes post-cold war to reconceptualize development and security in terms that move beyond description and into substantive change especially regarding shifting the development discourse from its historic modernizing impulses.
- Full Text:
- Date Issued: 2015
- Authors: Magadla, Siphokazi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298640 , vital:57723 , xlink:href="https://doi.org/10.1080/02589346.2015.1008676"
- Description: Mark Duffield's second edition of ‘Global Governance and the New Wars’ offers an important and biting critique of how different actors within the security and development discourse have adapted to the various transformations of war in the post-cold war era. In this picture drawn by Duffield, the power of states in the South continues to be eroded by an exclusionary market that is driven by the global political economy wherein state's development and security responsibilities are increasingly assumed by non-state actors (predominately constituted by Western aid agencies). Those who fall outside the bounds of the state, development and humanitarian aid agencies can be found operating in an expanding shadow economy that is also shaped by a global dynamics which make the conditions for ‘network war' possible. In this context, the lines between ‘war' and peace” are difficult to distinguish. Overall, the book paints a depressing picture on the lack of substantive changes in the livelihoods of the poor as attention has been directed to discussions about ‘new wars' or altered forms of violence that have characterized the post-cold war era. The book unforgivingly exposes the failures of the discursive changes post-cold war to reconceptualize development and security in terms that move beyond description and into substantive change especially regarding shifting the development discourse from its historic modernizing impulses.
- Full Text:
- Date Issued: 2015
Characterization of porphyrin nanorods on fluorine doped tin oxide glass sheet
- George, Reama C, Falgenhauer, Jane, Geis, Clemens, Nyokong, Tebello, Schlettwein, Derck
- Authors: George, Reama C , Falgenhauer, Jane , Geis, Clemens , Nyokong, Tebello , Schlettwein, Derck
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193542 , vital:45344 , xlink:href="https://doi.org/10.1142/S1088424615500923"
- Description: Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS4)4) served as negatively charged counterpart for the positively charged metallo meso-tetra(4-NN-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During cyclic voltammetry either applying negative potentials from 0.0 V to -1.0 V or positive potentials from 0.0 V to ++2.2 V irreversible reduction or oxidation reactions were detected for the films. Consistently, SEM images taken following cyclic voltammetry showed the disintegration of the PNR on the films into smaller subunits. Spectroelectrochemical measurements showed the formation of porphyrin anionic radicals during oxidation by a decrease in the absorption intensities and broadening of spectra with an additional band appearing around 900 nm. A similar trend was observed when negative potentials were applied but in this case the cationic radical was produced. In both cases the decrease of the intensity of the J-aggregate confirms a loss of intermolecular coupling, again consistent with the smaller subunits observed in SEM analysis.
- Full Text:
- Date Issued: 2015
- Authors: George, Reama C , Falgenhauer, Jane , Geis, Clemens , Nyokong, Tebello , Schlettwein, Derck
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193542 , vital:45344 , xlink:href="https://doi.org/10.1142/S1088424615500923"
- Description: Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS4)4) served as negatively charged counterpart for the positively charged metallo meso-tetra(4-NN-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During cyclic voltammetry either applying negative potentials from 0.0 V to -1.0 V or positive potentials from 0.0 V to ++2.2 V irreversible reduction or oxidation reactions were detected for the films. Consistently, SEM images taken following cyclic voltammetry showed the disintegration of the PNR on the films into smaller subunits. Spectroelectrochemical measurements showed the formation of porphyrin anionic radicals during oxidation by a decrease in the absorption intensities and broadening of spectra with an additional band appearing around 900 nm. A similar trend was observed when negative potentials were applied but in this case the cationic radical was produced. In both cases the decrease of the intensity of the J-aggregate confirms a loss of intermolecular coupling, again consistent with the smaller subunits observed in SEM analysis.
- Full Text:
- Date Issued: 2015
Characterization of some amino acid derivatives of benzoyl isothiocyanate: Crystal structures and theoretical prediction of their reactivity
- Odame, Felix, Hosten, Eric C, Betz, Richard, Lobb, Kevin A, Tshentu, Zenixole R
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447952 , vital:74686 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.05.053"
- Description: The reaction of benzoyl isothiocyanate with L-serine, L-proline, D-methionine and L-alanine gave 2-[(benzoylcarbamothioyl)amino]-3-hydroxypropanoic acid (I), 1-(benzoylcarbamothioyl)pyrrolidine-2-carboxylic acid (II), 2-[(benzoylcarbamothioyl)amino]-4-(methylsulfanyl)butanoic acid (III) and 2-[(benzoylcarbamothioyl)amino]propanoic acid (IV), respectively. The compounds have been characterized by IR, NMR, microanalyses and mass spectrometry. The crystal structures of all the compounds have also been discussed. Compound II showed rotamers in solution. DFT calculations of the frontier orbitals of the compounds have been carried out to ascertain the groups that contribute to the HOMO and LUMO, and to study their contribution to the reactivity of these compounds. The calculations indicated that the carboxylic acid group in these compounds is unreactive hence making the conversion to benzimidazoles via cyclization on the carboxylic acids impractical. This has been further confirmed by the reaction of compounds I–IV, respectively, with o-phenylene diamine which was unsuccessful but gave compound V.
- Full Text:
- Date Issued: 2015
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447952 , vital:74686 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.05.053"
- Description: The reaction of benzoyl isothiocyanate with L-serine, L-proline, D-methionine and L-alanine gave 2-[(benzoylcarbamothioyl)amino]-3-hydroxypropanoic acid (I), 1-(benzoylcarbamothioyl)pyrrolidine-2-carboxylic acid (II), 2-[(benzoylcarbamothioyl)amino]-4-(methylsulfanyl)butanoic acid (III) and 2-[(benzoylcarbamothioyl)amino]propanoic acid (IV), respectively. The compounds have been characterized by IR, NMR, microanalyses and mass spectrometry. The crystal structures of all the compounds have also been discussed. Compound II showed rotamers in solution. DFT calculations of the frontier orbitals of the compounds have been carried out to ascertain the groups that contribute to the HOMO and LUMO, and to study their contribution to the reactivity of these compounds. The calculations indicated that the carboxylic acid group in these compounds is unreactive hence making the conversion to benzimidazoles via cyclization on the carboxylic acids impractical. This has been further confirmed by the reaction of compounds I–IV, respectively, with o-phenylene diamine which was unsuccessful but gave compound V.
- Full Text:
- Date Issued: 2015
Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4, 6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt (II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015