Electrocatalytic detection of l-cysteine using molybdenum POM doped-HKUST-1 metal organic frameworks
- Murinzi, Tafadzwa W, Watkins, Gareth M, Shumba, Munyaradzi, Nyokong, Tebello
- Authors: Murinzi, Tafadzwa W , Watkins, Gareth M , Shumba, Munyaradzi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185748 , vital:44420 , xlink:href="https://doi.org/10.1080/00958972.2021.1907573"
- Description: Glass carbon electrodes (GCE) were modified with metal organic frameworks (MOFs) containing molybdenum polyoxometallates (Mo POMs) in a copper benzene tricarboxylate framework (HKUST-1). The Mo POMs were introduced via one-pot synthesis (Mo2) and post-synthetic modification (Mo1) techniques. The electrode modifiers were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal analysis. The modified electrodes’ oxidation capacity toward L-cysteine was studied. Mo POMs significantly improved electron transfer kinetics compared to the bare GCE. The best Mo POM doped electrode (Mo1-GCE) had a catalytic rate constant of 2.2 × 104 M−1 s−1 and a limit of detection of 3.07 × 10−7 M. Under the employed experimental conditions, the detection response for L-cysteine was very fast (within 0.1 s) for all the modified electrodes and selective toward L-cysteine in the presence of other amino acids.
- Full Text:
- Date Issued: 2021
Electrocatalytic detection of l-cysteine using molybdenum POM doped-HKUST-1 metal organic frameworks
- Authors: Murinzi, Tafadzwa W , Watkins, Gareth M , Shumba, Munyaradzi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185748 , vital:44420 , xlink:href="https://doi.org/10.1080/00958972.2021.1907573"
- Description: Glass carbon electrodes (GCE) were modified with metal organic frameworks (MOFs) containing molybdenum polyoxometallates (Mo POMs) in a copper benzene tricarboxylate framework (HKUST-1). The Mo POMs were introduced via one-pot synthesis (Mo2) and post-synthetic modification (Mo1) techniques. The electrode modifiers were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal analysis. The modified electrodes’ oxidation capacity toward L-cysteine was studied. Mo POMs significantly improved electron transfer kinetics compared to the bare GCE. The best Mo POM doped electrode (Mo1-GCE) had a catalytic rate constant of 2.2 × 104 M−1 s−1 and a limit of detection of 3.07 × 10−7 M. Under the employed experimental conditions, the detection response for L-cysteine was very fast (within 0.1 s) for all the modified electrodes and selective toward L-cysteine in the presence of other amino acids.
- Full Text:
- Date Issued: 2021
Electrochemical detection of dopamine using phthalocyanine-nitrogen-doped graphene quantum dot conjugates
- Ndebele Nobuhle, Sen, Pinar, Nyokong, Tebello
- Authors: Ndebele Nobuhle , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185724 , vital:44418 , xlink:href="https://doi.org/10.1016/j.jelechem.2021.115111"
- Description: Two cobalt phthalocyanine molecules were synthesized, a symmetrically substituted CoPc (1) and an unsymmetrically substituted CoPc (2). These CoPcs were π-π stacked onto nitrogen-doped graphene quantum dots (NGQDs). The CoPcs, NGQDs and their respective conjugates were used as electro-catalytic probes in the electrochemical oxidation of dopamine. The molecules were adsorbed onto a glassy carbon electrode (GCE) using the drop dry method, the GCE was used to support those catalysts. The electrooxidation of dopamine was studied using cyclic voltammetry and chronoamperometry. An improvement in the sensitivity and limit of detection was observed upon conjugation.
- Full Text:
- Date Issued: 2021
- Authors: Ndebele Nobuhle , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185724 , vital:44418 , xlink:href="https://doi.org/10.1016/j.jelechem.2021.115111"
- Description: Two cobalt phthalocyanine molecules were synthesized, a symmetrically substituted CoPc (1) and an unsymmetrically substituted CoPc (2). These CoPcs were π-π stacked onto nitrogen-doped graphene quantum dots (NGQDs). The CoPcs, NGQDs and their respective conjugates were used as electro-catalytic probes in the electrochemical oxidation of dopamine. The molecules were adsorbed onto a glassy carbon electrode (GCE) using the drop dry method, the GCE was used to support those catalysts. The electrooxidation of dopamine was studied using cyclic voltammetry and chronoamperometry. An improvement in the sensitivity and limit of detection was observed upon conjugation.
- Full Text:
- Date Issued: 2021
Electrochemical Detection of Nitrite on Electrodes Modified by Click Chemistry Using Asymmetrical Co (II) and Mn (III) Phthalocyanines Containing Push-Pull Substituents
- Nkhahle, Reitumetse, Nyokong, Tebello
- Authors: Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231425 , vital:49886 , xlink:href="https://doi.org/10.1149/1945-7111/ac377f"
- Description: The more conventional route to synthesizing asymmetric push-pull phthalocyanines (Pcs) involves pairing electron-donating substituents with electron-withdrawing groups in either an A3B or AB3 manner. In this work, a push-pull system fashioned from a substituent bearing different functional groups was created. Symmetric and asymmetric cobalt and manganese Pcs in which acetaminophen was the dominant substituent were synthesized where the asymmetric analogues bore an alkyne-terminated substituent. These complexes were applied as sensors towards the electro-oxidation of nitrite. In addition to comparing the asymmetric Pcs to the symmetric counterparts, an assessment on the different central metals as well as the method of electrode modification was made. From the studies performed, the results showed that the manganese complexes are generally better suited (more so when clicked on to the electrode) in the electrocatalysis of nitrite with a limit of detection and a catalytic rate values of 2.15 μM and 6.91 × 106 s−1 M−1 being recorded for the asymmetric MnPc.
- Full Text:
- Date Issued: 2021
- Authors: Nkhahle, Reitumetse , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231425 , vital:49886 , xlink:href="https://doi.org/10.1149/1945-7111/ac377f"
- Description: The more conventional route to synthesizing asymmetric push-pull phthalocyanines (Pcs) involves pairing electron-donating substituents with electron-withdrawing groups in either an A3B or AB3 manner. In this work, a push-pull system fashioned from a substituent bearing different functional groups was created. Symmetric and asymmetric cobalt and manganese Pcs in which acetaminophen was the dominant substituent were synthesized where the asymmetric analogues bore an alkyne-terminated substituent. These complexes were applied as sensors towards the electro-oxidation of nitrite. In addition to comparing the asymmetric Pcs to the symmetric counterparts, an assessment on the different central metals as well as the method of electrode modification was made. From the studies performed, the results showed that the manganese complexes are generally better suited (more so when clicked on to the electrode) in the electrocatalysis of nitrite with a limit of detection and a catalytic rate values of 2.15 μM and 6.91 × 106 s−1 M−1 being recorded for the asymmetric MnPc.
- Full Text:
- Date Issued: 2021
Electrografting of isophthalic acid monolayer and covalent attachment of antibody onto carbon surfaces
- Mwanza, Daniel, Phal, Sereilakhena, Nyokong, Tebello, Tesfalidet, Solomon, Mashazi, Philani N
- Authors: Mwanza, Daniel , Phal, Sereilakhena , Nyokong, Tebello , Tesfalidet, Solomon , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231345 , vital:49879 , xlink:href="https://doi.org/10.1016/j.electacta.2021.139360"
- Description: In this study, a 5-diazonium isophthalic acid was synthesized and electrografted onto glassy carbon (GCE) and screen-printed carbon (SPCE) electrodes. SPCE was used to demonstrate fabrication of a miniature device and to compare with conventional glassy carbon electrodes. The isophthalic acid (IPA) electrografted thin film was used for the immobilization of anti-methotrexate antibody (Ab) using carbodiimide activation chemistry to form antibody modified surfaces, GCE-IPA-Ab and SPCE-IPA-Ab. The GCE -IPA-Ab and SPCE-IPA-Ab surfaces were used as capacitive biosensors for the detection of methotrexate (MTX) in phosphate buffer (pH 7.4) using capacitive electrochemical impedance spectroscopy (EIS). The EIS data was analyzed using singular value decomposition (SVD). Principal component regression analysis gave R2 values of 0.99 for both the GCE-IPA-Ab and SPCE-IPA-Ab surfaces. The detection limit from the calibration curve of the GCE-IPA-Ab and SPCE-IPA-Ab was calculated to be 7.0 pmol.L−1 and 5.5 pmol.L−1, respectively.
- Full Text:
- Date Issued: 2021
- Authors: Mwanza, Daniel , Phal, Sereilakhena , Nyokong, Tebello , Tesfalidet, Solomon , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231345 , vital:49879 , xlink:href="https://doi.org/10.1016/j.electacta.2021.139360"
- Description: In this study, a 5-diazonium isophthalic acid was synthesized and electrografted onto glassy carbon (GCE) and screen-printed carbon (SPCE) electrodes. SPCE was used to demonstrate fabrication of a miniature device and to compare with conventional glassy carbon electrodes. The isophthalic acid (IPA) electrografted thin film was used for the immobilization of anti-methotrexate antibody (Ab) using carbodiimide activation chemistry to form antibody modified surfaces, GCE-IPA-Ab and SPCE-IPA-Ab. The GCE -IPA-Ab and SPCE-IPA-Ab surfaces were used as capacitive biosensors for the detection of methotrexate (MTX) in phosphate buffer (pH 7.4) using capacitive electrochemical impedance spectroscopy (EIS). The EIS data was analyzed using singular value decomposition (SVD). Principal component regression analysis gave R2 values of 0.99 for both the GCE-IPA-Ab and SPCE-IPA-Ab surfaces. The detection limit from the calibration curve of the GCE-IPA-Ab and SPCE-IPA-Ab was calculated to be 7.0 pmol.L−1 and 5.5 pmol.L−1, respectively.
- Full Text:
- Date Issued: 2021
Elucidating Tuta absoluta (Meyrick) invasion and enhancing its management in Eastern Africa : spread, socio-ecological impacts, and potential of a newly imported larval parasitoid for classical biological control Eastern in Africa
- Aigbedion-Atalor, Pascal Osabhahiemen
- Authors: Aigbedion-Atalor, Pascal Osabhahiemen
- Date: 2021
- Subjects: Tuta absoluta -- Biological control , Tomatoes -- Diseases and pests -- Africa, East , Braconidae , Gelechiidae -- Biological control -- Africa, East , Insects as biological pest control agents -- Africa, East
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/170421 , vital:41920 , 10.21504/10962/170421
- Description: Agriculture is a fundamental source of sustainable livelihoods in sub-Saharan Africa and millions of people in the region rely solely on small-scale farming for their food security. However, the impacts of invasive alien species (IAS) on crop production are serious, and there is no sign of this abating. Among the recent IAS that have invaded Africa in the last decade, the South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has been one of the most damaging. Following its first record in the Maghreb region of Africa in 2008, T. absoluta rapidly spread throughout Africa with substantial impacts on tomato production, often causing 100% yield loss. Management options adopted against T. absoluta by tomato growers in Africa have been based on the use of synthetic insecticides. While chemical insecticide applications are an important component of an integrated pest management programme, misuse and over-reliance often exacerbates the impacts of T. absolutadue to the development of resistance to commonly used active substances, increasing the fitness of the pest. This thesis sought to understand the socio-economic impacts of the spread of T. absoluta in Eastern Africa and provide effective sustainable pest management strategies to reduce its impacts below economic thresholds. Mapping surveys of Tabsoluta were conducted in 226 tomato agro-ecosystems across four eastern countries (Kenya, Sudan, Tanzania, and Uganda) Eastern Africa from 2016 to 2018 to determine the spatiotemporal distribution of the pest. The impacts of T. absoluta on the livelihoods of tomato growers were also assessed. Here, 200 tomato growers in Kenya were interviewed using a semi-structured questionnaire. Although T. absoluta, a recent invader, was distributed at high infestation levels throughout the subregion (all four countries) and was considered as the most damaging invasive alien species of agriculturally sustainable livelihoods. The arrival of T. absoluta in the subregion has resulted in livelihood losses and increased the cost of tomato production and price of the fruit, and the frequency of pesticide applications. The impact of this pest and the and the absence of effective indigenous natural enemies of the pest in Eastern Africa, was the rationale for the importation of a larval parasitoid, Dolichogenidea gelechiidivoris Marsh Syn.: Apanteles gelechiidivoris Marsh) (Hymenoptera: Braconidae), of T. absoluta from Peru into the quarantine facility of the International Centre of Insect Physiology and ecologyz(icipe), in Kenya. Pre-release assessments on the parasitzation potential of D. gelechiidivoris, encompassing host larval preference and the host suitability, and its reproductive strategy, for classical biological control of T. absoluta in Africa were conducted. Dolichogenidea gelechiidivoris females preferentially oviposited in early (1st and 2nd) larval instars of T. absoluta but parasitized and completed development in all four instars of the host. Host instar did not affect D. gelechiidivoris sex-ratio but females reared on the first instar had significantly fewer eggs than when reared in late larval instars (3rd and 4th). Females of the parasitoid emerged with a high mature egg load which peaked 2 d post-eclosion. The females of D. gelechiidivoris survived 8.51±0.65 d and produced 103±8 offspring per female at 26±4°C (range: 24 to 29°C) and 50–70% relative humidity (RH) in the presence of males and fed honey-water (80% honey). Increasing maternal age decreased the proportion of female offspring. Under the aforementioned laboratory conditions, the Gross and Net reproductive rates were 72 and 39.5 respectively, while the mean generation time was 20 d. The estimated intrinsic rate of natural increase was 0.18. These findings indicate that D. gelechiidivorisis a potential biological control agent of T. absoluta and should be considered for augmentative/inundative release in Kenya and across Africa following host specificity testing and risk assessments. The nature of the interaction between D. gelechidivoris and the predatory mirid bug Nesidiocoris tenuis(Reuter) (Hemiptera: Miridae), an important and widespread natural enemy of T. absoluta in Africa was evaluated because N. tenuis, although being a voracious predator of T. absoluta eggs, it can also prey on the early host larval instars (1st and 2nd) which are the preferred oviposition host stages of D. gelechiidivoris. Here, the impact of N. tenuis feeding on T. absoluta and the effects on D. gelechiidivoris performance was tested. Regardless of the order of introductions (i.e. the sequence of combination with D. gelechiidivoris) and densities (i.e. number of N. tenuis combined with D. gelechiidivoris), there was no intraguild predation by N. tenuis on D. gelechiidivorisas there was little host larval feeding behaviour. Also, the presence of N. tenuis did not affect the oviposition performance of D. gelechiidivoris. Further investigations revealed that the combined efficacy of N. tenuis and D. gelechiidivorison T. absoluta population was significantly higher than either natural enemy alone, thus contributes to the data supporting the release of D. gelechiidivoris in Africa. In concluding, integrating D. gelechiidivoris and N. tenuis in the management of T. absolut could potentially reduce yield losses in tomato in Eastern Africa where the socio-economic impacts of the pest are very serious.
- Full Text:
- Date Issued: 2021
- Authors: Aigbedion-Atalor, Pascal Osabhahiemen
- Date: 2021
- Subjects: Tuta absoluta -- Biological control , Tomatoes -- Diseases and pests -- Africa, East , Braconidae , Gelechiidae -- Biological control -- Africa, East , Insects as biological pest control agents -- Africa, East
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/170421 , vital:41920 , 10.21504/10962/170421
- Description: Agriculture is a fundamental source of sustainable livelihoods in sub-Saharan Africa and millions of people in the region rely solely on small-scale farming for their food security. However, the impacts of invasive alien species (IAS) on crop production are serious, and there is no sign of this abating. Among the recent IAS that have invaded Africa in the last decade, the South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has been one of the most damaging. Following its first record in the Maghreb region of Africa in 2008, T. absoluta rapidly spread throughout Africa with substantial impacts on tomato production, often causing 100% yield loss. Management options adopted against T. absoluta by tomato growers in Africa have been based on the use of synthetic insecticides. While chemical insecticide applications are an important component of an integrated pest management programme, misuse and over-reliance often exacerbates the impacts of T. absolutadue to the development of resistance to commonly used active substances, increasing the fitness of the pest. This thesis sought to understand the socio-economic impacts of the spread of T. absoluta in Eastern Africa and provide effective sustainable pest management strategies to reduce its impacts below economic thresholds. Mapping surveys of Tabsoluta were conducted in 226 tomato agro-ecosystems across four eastern countries (Kenya, Sudan, Tanzania, and Uganda) Eastern Africa from 2016 to 2018 to determine the spatiotemporal distribution of the pest. The impacts of T. absoluta on the livelihoods of tomato growers were also assessed. Here, 200 tomato growers in Kenya were interviewed using a semi-structured questionnaire. Although T. absoluta, a recent invader, was distributed at high infestation levels throughout the subregion (all four countries) and was considered as the most damaging invasive alien species of agriculturally sustainable livelihoods. The arrival of T. absoluta in the subregion has resulted in livelihood losses and increased the cost of tomato production and price of the fruit, and the frequency of pesticide applications. The impact of this pest and the and the absence of effective indigenous natural enemies of the pest in Eastern Africa, was the rationale for the importation of a larval parasitoid, Dolichogenidea gelechiidivoris Marsh Syn.: Apanteles gelechiidivoris Marsh) (Hymenoptera: Braconidae), of T. absoluta from Peru into the quarantine facility of the International Centre of Insect Physiology and ecologyz(icipe), in Kenya. Pre-release assessments on the parasitzation potential of D. gelechiidivoris, encompassing host larval preference and the host suitability, and its reproductive strategy, for classical biological control of T. absoluta in Africa were conducted. Dolichogenidea gelechiidivoris females preferentially oviposited in early (1st and 2nd) larval instars of T. absoluta but parasitized and completed development in all four instars of the host. Host instar did not affect D. gelechiidivoris sex-ratio but females reared on the first instar had significantly fewer eggs than when reared in late larval instars (3rd and 4th). Females of the parasitoid emerged with a high mature egg load which peaked 2 d post-eclosion. The females of D. gelechiidivoris survived 8.51±0.65 d and produced 103±8 offspring per female at 26±4°C (range: 24 to 29°C) and 50–70% relative humidity (RH) in the presence of males and fed honey-water (80% honey). Increasing maternal age decreased the proportion of female offspring. Under the aforementioned laboratory conditions, the Gross and Net reproductive rates were 72 and 39.5 respectively, while the mean generation time was 20 d. The estimated intrinsic rate of natural increase was 0.18. These findings indicate that D. gelechiidivorisis a potential biological control agent of T. absoluta and should be considered for augmentative/inundative release in Kenya and across Africa following host specificity testing and risk assessments. The nature of the interaction between D. gelechidivoris and the predatory mirid bug Nesidiocoris tenuis(Reuter) (Hemiptera: Miridae), an important and widespread natural enemy of T. absoluta in Africa was evaluated because N. tenuis, although being a voracious predator of T. absoluta eggs, it can also prey on the early host larval instars (1st and 2nd) which are the preferred oviposition host stages of D. gelechiidivoris. Here, the impact of N. tenuis feeding on T. absoluta and the effects on D. gelechiidivoris performance was tested. Regardless of the order of introductions (i.e. the sequence of combination with D. gelechiidivoris) and densities (i.e. number of N. tenuis combined with D. gelechiidivoris), there was no intraguild predation by N. tenuis on D. gelechiidivorisas there was little host larval feeding behaviour. Also, the presence of N. tenuis did not affect the oviposition performance of D. gelechiidivoris. Further investigations revealed that the combined efficacy of N. tenuis and D. gelechiidivorison T. absoluta population was significantly higher than either natural enemy alone, thus contributes to the data supporting the release of D. gelechiidivoris in Africa. In concluding, integrating D. gelechiidivoris and N. tenuis in the management of T. absolut could potentially reduce yield losses in tomato in Eastern Africa where the socio-economic impacts of the pest are very serious.
- Full Text:
- Date Issued: 2021
Emergent Curriculum and Sustainability Competencies in Environmental Learning
- Mkhabela, Antonia T, Schudel, Ingrid J
- Authors: Mkhabela, Antonia T , Schudel, Ingrid J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435112 , vital:73131 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: This study was influenced by the South African National Diagnostic Report on Learner Performance in the 2012 final examinations, which highlighted learner struggles with ‘higher order thinking skills such as application, problem solving, critical thinking, analysis and evaluation’ (South Africa DBE 2013: 16). These are skills typically associated with essay questions in examinations. Another issue reported in the abovementioned document was poorly answered essay questions on Environmental Studies, ‘giving the impression that this topic, which is scheduled towards the end of the year, was neglected by both teachers and learners’ (p. 121). The problem of weak higher order thinking skills, compounded by difficulty with Environmental Studies, informed part of the research interest for this study: namely, how higher order thinking is engaged when reflecting on environmental issues in Life Sciences classrooms (specifically required for the Environmental Studies topic of ‘human impact’).
- Full Text:
- Date Issued: 2021
- Authors: Mkhabela, Antonia T , Schudel, Ingrid J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435112 , vital:73131 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: This study was influenced by the South African National Diagnostic Report on Learner Performance in the 2012 final examinations, which highlighted learner struggles with ‘higher order thinking skills such as application, problem solving, critical thinking, analysis and evaluation’ (South Africa DBE 2013: 16). These are skills typically associated with essay questions in examinations. Another issue reported in the abovementioned document was poorly answered essay questions on Environmental Studies, ‘giving the impression that this topic, which is scheduled towards the end of the year, was neglected by both teachers and learners’ (p. 121). The problem of weak higher order thinking skills, compounded by difficulty with Environmental Studies, informed part of the research interest for this study: namely, how higher order thinking is engaged when reflecting on environmental issues in Life Sciences classrooms (specifically required for the Environmental Studies topic of ‘human impact’).
- Full Text:
- Date Issued: 2021
Encouraging and discouraging factors to crime reporting in South Africa: a survey of residents’ crime reporting behaviour in Mthatha South Africa police service precinct
- Mbewu, Ithandile, Obioha, Emeka E, Mugari , Ishmael
- Authors: Mbewu, Ithandile , Obioha, Emeka E , Mugari , Ishmael
- Date: 2021
- Subjects: Crime Citizen crime reporting Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6967 , vital:52622 , xlink:href="https://doi.org/10.1080/23311886.2021.2002542"
- Description: The aim of this study was to explore issues concerning dispositions of crime-reporting behaviour of both witnesses and victims and comes against a backdrop of a rise in crime levels in South Africa. The study specifically examined the discouraging and encouraging factors for crime reporting in Mthatha area in the Eastern Cape Province of South Africa. A quantitative methodology was adopted, wherein a closed-ended questionnaire was used to gather data from 120 respondents. The result of the analysis revealed police absence of loyalty to citizens, lack of support for victims and lack of follow-up on reported cases as the major factors which discourage citizens from reporting crimes to the police. Further regression analysis confirmed gender, race, location of respondents and socio-economic status as significant predictors that influence discouragement. As regards the encouraging factors, overall, the citizens’ collective responsibility for safe communities was viewed as the major drive for reporting crimes to the police. From the findings, it can be concluded that poor police-public relations is the main driver for non-reporting of crime. The study recommends strengthening of police-public relations in order to encourage citizens to report crime.
- Full Text:
- Date Issued: 2021
- Authors: Mbewu, Ithandile , Obioha, Emeka E , Mugari , Ishmael
- Date: 2021
- Subjects: Crime Citizen crime reporting Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6967 , vital:52622 , xlink:href="https://doi.org/10.1080/23311886.2021.2002542"
- Description: The aim of this study was to explore issues concerning dispositions of crime-reporting behaviour of both witnesses and victims and comes against a backdrop of a rise in crime levels in South Africa. The study specifically examined the discouraging and encouraging factors for crime reporting in Mthatha area in the Eastern Cape Province of South Africa. A quantitative methodology was adopted, wherein a closed-ended questionnaire was used to gather data from 120 respondents. The result of the analysis revealed police absence of loyalty to citizens, lack of support for victims and lack of follow-up on reported cases as the major factors which discourage citizens from reporting crimes to the police. Further regression analysis confirmed gender, race, location of respondents and socio-economic status as significant predictors that influence discouragement. As regards the encouraging factors, overall, the citizens’ collective responsibility for safe communities was viewed as the major drive for reporting crimes to the police. From the findings, it can be concluded that poor police-public relations is the main driver for non-reporting of crime. The study recommends strengthening of police-public relations in order to encourage citizens to report crime.
- Full Text:
- Date Issued: 2021
Engaging Education for Sustainable Development as Quality Education in the Fundisa for Change Programme
- Schudel, Ingrid J, Lotz-Sisitka, Heila, Songqwaru, Zintle, Tshiningayamwe, Sirkka
- Authors: Schudel, Ingrid J , Lotz-Sisitka, Heila , Songqwaru, Zintle , Tshiningayamwe, Sirkka
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435031 , vital:73125 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: Since the Industrial Revolution began in the late 18th century, development has provided humankind with numerous benefits, such as modern medicine, housing, transport and communication systems. However, progress and the contemporary model of development has also brought its problems, as non-renewable resources have been overextracted, and large volumes of waste created, resulting in pollution that has impacted on the health of people and the environment. Most people are now aware that human actions are changing the climate in unpredictable ways. Massive over-consumption of resources and continued environmental degradation are undermining the natural systems we depend on, impacting most severely on the poor and marginalised people in our society. Societies around the world must adapt and change their practices for a low-carbon, more sustainable future.
- Full Text:
- Date Issued: 2021
- Authors: Schudel, Ingrid J , Lotz-Sisitka, Heila , Songqwaru, Zintle , Tshiningayamwe, Sirkka
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435031 , vital:73125 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: Since the Industrial Revolution began in the late 18th century, development has provided humankind with numerous benefits, such as modern medicine, housing, transport and communication systems. However, progress and the contemporary model of development has also brought its problems, as non-renewable resources have been overextracted, and large volumes of waste created, resulting in pollution that has impacted on the health of people and the environment. Most people are now aware that human actions are changing the climate in unpredictable ways. Massive over-consumption of resources and continued environmental degradation are undermining the natural systems we depend on, impacting most severely on the poor and marginalised people in our society. Societies around the world must adapt and change their practices for a low-carbon, more sustainable future.
- Full Text:
- Date Issued: 2021
Enhanced photo-ablation effect of positively charged phthalocyanines-detonation nanodiamonds nanoplatforms for the suppression of Staphylococcus aureus and Escherichia coli planktonic cells and biofilms
- Openda, Yolande I, Nyokong, Tebello
- Authors: Openda, Yolande I , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185712 , vital:44417 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113200"
- Description: Photodynamic antimicrobial therapy (PACT) is a powerful technic recommended to eliminate life-threatening pathogens that cause localized and superficial infections as pathogens cannot develop resistance to it. For this reason, new positively charged chalcone substituted zinc (3a) and indium (4a) metalated phthalocyanines (Pcs) were synthesized and were π-π interacted with detonation nanodiamonds (DNDs) nanoparticles to form new water soluble nanoplatfoms 3a@DNDs and 4a@DNDs. The conjugates generated high singlet oxygen quantum yields (ΦΔ) in water (1% DMSO, used for PACT studies) with values of 0.46 and 0.47 for 3a@DNDs and 4a@DNDs, respectively. Hence, they were tested for PACT against biofilms of S. aureus and E. coli, as well as their planktonic cells. The quaternized Pcs alone 3a and 4a as well as their nanoconjugates 3a@DNDs and 4a@DNDs were effective PACT agents with log10 CFU > 9 for E. coli and S. aureus. The quaternized derivatives were found to have higher ability to completely suppress both planktonic and biofilms of S. aureus and E. coli in vitro. Therefore, they could be used as appropriate photosensitive agents.
- Full Text:
- Date Issued: 2021
- Authors: Openda, Yolande I , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185712 , vital:44417 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113200"
- Description: Photodynamic antimicrobial therapy (PACT) is a powerful technic recommended to eliminate life-threatening pathogens that cause localized and superficial infections as pathogens cannot develop resistance to it. For this reason, new positively charged chalcone substituted zinc (3a) and indium (4a) metalated phthalocyanines (Pcs) were synthesized and were π-π interacted with detonation nanodiamonds (DNDs) nanoparticles to form new water soluble nanoplatfoms 3a@DNDs and 4a@DNDs. The conjugates generated high singlet oxygen quantum yields (ΦΔ) in water (1% DMSO, used for PACT studies) with values of 0.46 and 0.47 for 3a@DNDs and 4a@DNDs, respectively. Hence, they were tested for PACT against biofilms of S. aureus and E. coli, as well as their planktonic cells. The quaternized Pcs alone 3a and 4a as well as their nanoconjugates 3a@DNDs and 4a@DNDs were effective PACT agents with log10 CFU > 9 for E. coli and S. aureus. The quaternized derivatives were found to have higher ability to completely suppress both planktonic and biofilms of S. aureus and E. coli in vitro. Therefore, they could be used as appropriate photosensitive agents.
- Full Text:
- Date Issued: 2021
Enhanced upconversion emission of Er3+-Yb3+ co-doped Ba5 (PO4) 3OH powder phosphor for application in photodynamic therapy
- Mokoena, Puseletso P, Poluwole, David O, Nyokong, Tebello, Swart, Hendrik C, Ntwaeaborwa, Odireleng M
- Authors: Mokoena, Puseletso P , Poluwole, David O , Nyokong, Tebello , Swart, Hendrik C , Ntwaeaborwa, Odireleng M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185035 , vital:44318 , xlink:href="https://doi.org/10.1016/j.sna.2021.113014"
- Description: Er3+-Yb3+ co-doped Ba5(PO4)3OH nanoparticle powder phosphors were successfully synthesized by urea combustion method. The resulting powder phosphors were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). XRD data confirmed crystallization of pure hexagonal phase of Ba5(PO4)3OH and HRSEM images showed formation of ellipsoidal particles. XPS data combined with EDS analysis confirmed the materials composition that corresponds with identification of all the chemical elements constituting the materials. The in vitro dark cytotoxicity of the particles confirmed lack of cytocidal behaviour in the absence of light, but considerable photodynamic therapy (PDT) activity was observed upon illumination. Upon excitation using a 980 nm laser, multiple emission peaks in the green and red regions corresponding to the optical transitions of Er3+ ion were observed. Upon co-doping with Yb3+, upconverted red emission was detected and this was attributable to non-radiative energy transfer from Yb3+ to Er3+. The proposed mechanism of upconversion photoluminescence is discussed.
- Full Text:
- Date Issued: 2021
- Authors: Mokoena, Puseletso P , Poluwole, David O , Nyokong, Tebello , Swart, Hendrik C , Ntwaeaborwa, Odireleng M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185035 , vital:44318 , xlink:href="https://doi.org/10.1016/j.sna.2021.113014"
- Description: Er3+-Yb3+ co-doped Ba5(PO4)3OH nanoparticle powder phosphors were successfully synthesized by urea combustion method. The resulting powder phosphors were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). XRD data confirmed crystallization of pure hexagonal phase of Ba5(PO4)3OH and HRSEM images showed formation of ellipsoidal particles. XPS data combined with EDS analysis confirmed the materials composition that corresponds with identification of all the chemical elements constituting the materials. The in vitro dark cytotoxicity of the particles confirmed lack of cytocidal behaviour in the absence of light, but considerable photodynamic therapy (PDT) activity was observed upon illumination. Upon excitation using a 980 nm laser, multiple emission peaks in the green and red regions corresponding to the optical transitions of Er3+ ion were observed. Upon co-doping with Yb3+, upconverted red emission was detected and this was attributable to non-radiative energy transfer from Yb3+ to Er3+. The proposed mechanism of upconversion photoluminescence is discussed.
- Full Text:
- Date Issued: 2021
Enhancement of Biological and Pharmacological Properties of an Encapsulated Polyphenol: Curcumin
- Witika, Bwalya A, Makoni, Pedzisai A, Matafwali, Scott K, Mweetwa, Larry L, Shandele, Ginnethon C, Walker, Roderick B
- Authors: Witika, Bwalya A , Makoni, Pedzisai A , Matafwali, Scott K , Mweetwa, Larry L , Shandele, Ginnethon C , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183161 , vital:43917 , xlink:href="https://doi.org/10.3390/molecules26144244"
- Description: There is a dearth of natural remedies available for the treatment of an increasing number of diseases facing mankind. Natural products may provide an opportunity to produce formulations and therapeutic solutions to address this shortage. Curcumin (CUR), diferuloylmethane; I,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione is the major pigment in turmeric powder which has been reported to exhibit a number of health benefits including, antibacterial, antiviral, anti-cancer, anti-inflammatory and anti-oxidant properties. In this review, the authors attempt to highlight the biological and pharmacological properties of CUR in addition to emphasizing aspects relating to the biosynthesis, encapsulation and therapeutic effects of the compound. The information contained in this review was generated by considering published information in which evidence of enhanced biological and pharmacological properties of nano-encapsulated CUR was reported. CUR has contributed to a significant improvement in melanoma, breast, lung, gastro-intestinal, and genito-urinary cancer therapy. We highlight the impact of nano-encapsulated CUR for efficient inhibition of cell proliferation, even at low concentrations compared to the free CUR when considering anti-proliferation. Furthermore nano-encapsulated CUR exhibited bioactive properties, exerted cytotoxic and anti-oxidant effects by acting on endogenous and cholinergic anti-oxidant systems. CUR was reported to block Hepatitis C virus (HCV) entry into hepatic cells, inhibit MRSA proliferation, enhance wound healing and reduce bacterial load. Nano-encapsulated CUR has also shown bioactive properties when acting on antioxidant systems (endogenous and cholinergic). Future research is necessary and must focus on investigation of encapsulated CUR nano-particles in different models of human pathology.
- Full Text:
- Date Issued: 2021
- Authors: Witika, Bwalya A , Makoni, Pedzisai A , Matafwali, Scott K , Mweetwa, Larry L , Shandele, Ginnethon C , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183161 , vital:43917 , xlink:href="https://doi.org/10.3390/molecules26144244"
- Description: There is a dearth of natural remedies available for the treatment of an increasing number of diseases facing mankind. Natural products may provide an opportunity to produce formulations and therapeutic solutions to address this shortage. Curcumin (CUR), diferuloylmethane; I,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione is the major pigment in turmeric powder which has been reported to exhibit a number of health benefits including, antibacterial, antiviral, anti-cancer, anti-inflammatory and anti-oxidant properties. In this review, the authors attempt to highlight the biological and pharmacological properties of CUR in addition to emphasizing aspects relating to the biosynthesis, encapsulation and therapeutic effects of the compound. The information contained in this review was generated by considering published information in which evidence of enhanced biological and pharmacological properties of nano-encapsulated CUR was reported. CUR has contributed to a significant improvement in melanoma, breast, lung, gastro-intestinal, and genito-urinary cancer therapy. We highlight the impact of nano-encapsulated CUR for efficient inhibition of cell proliferation, even at low concentrations compared to the free CUR when considering anti-proliferation. Furthermore nano-encapsulated CUR exhibited bioactive properties, exerted cytotoxic and anti-oxidant effects by acting on endogenous and cholinergic anti-oxidant systems. CUR was reported to block Hepatitis C virus (HCV) entry into hepatic cells, inhibit MRSA proliferation, enhance wound healing and reduce bacterial load. Nano-encapsulated CUR has also shown bioactive properties when acting on antioxidant systems (endogenous and cholinergic). Future research is necessary and must focus on investigation of encapsulated CUR nano-particles in different models of human pathology.
- Full Text:
- Date Issued: 2021
Enhancing Capabilities of Life Sciences Teachers: Professional Development, Conversion Factors and Functionings in Teachers’ Professional Learning Communities
- Tshiningayamwe, Sirkka, Lotz-Sisitka, Heila
- Authors: Tshiningayamwe, Sirkka , Lotz-Sisitka, Heila
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435220 , vital:73139 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: South Africa is rich in biodiversity and is home to about 95 000 known species (South Africa DEA 2014; SANBI 2019). Yet, compared to other southern African countries, the country has a high number of threatened species (Driver et al. 2012). Approximately 12 million South Africans depend on the natural environment to meet their needs. Among other factors, overharvesting of biological resources is one of the main causes of biodiversity loss in the country (South Africa DEA 2014; SANBI 2019). In line with assessment of biodiversity reports, Unesco (2018) notes that biodiversity loss is a global phenomenon. Emphasis in these reports is that over 7 billion people in the world rely on biodiversity to maintain and enhance their well-being. The realisation of biodiversity conservation as a global concern has resulted in various international conventions, policies, legislation and educational programmes that foreground biodiversity (Shava and Schudel 2013). Aligned with international trends, South Africa also has national policies and legislation aimed at protecting biodiversity. Among these is the National Environmental Management Biodiversity Act which introduces a legal framework for governing sustainable development in the country, and includes a clause for all training and education programmes to integrate education for sustainable development (RSA 1998). Thus, like many other countries in the world, South Africa has incorporated biodiversity components in its ongoing curriculum reforms including in the Curriculum Assessment Policy Statement (CAPS).
- Full Text:
- Date Issued: 2021
- Authors: Tshiningayamwe, Sirkka , Lotz-Sisitka, Heila
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435220 , vital:73139 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: South Africa is rich in biodiversity and is home to about 95 000 known species (South Africa DEA 2014; SANBI 2019). Yet, compared to other southern African countries, the country has a high number of threatened species (Driver et al. 2012). Approximately 12 million South Africans depend on the natural environment to meet their needs. Among other factors, overharvesting of biological resources is one of the main causes of biodiversity loss in the country (South Africa DEA 2014; SANBI 2019). In line with assessment of biodiversity reports, Unesco (2018) notes that biodiversity loss is a global phenomenon. Emphasis in these reports is that over 7 billion people in the world rely on biodiversity to maintain and enhance their well-being. The realisation of biodiversity conservation as a global concern has resulted in various international conventions, policies, legislation and educational programmes that foreground biodiversity (Shava and Schudel 2013). Aligned with international trends, South Africa also has national policies and legislation aimed at protecting biodiversity. Among these is the National Environmental Management Biodiversity Act which introduces a legal framework for governing sustainable development in the country, and includes a clause for all training and education programmes to integrate education for sustainable development (RSA 1998). Thus, like many other countries in the world, South Africa has incorporated biodiversity components in its ongoing curriculum reforms including in the Curriculum Assessment Policy Statement (CAPS).
- Full Text:
- Date Issued: 2021
Environmental entrepreneurship as an innovation catalyst for social change: A systematic review as a basis for future research
- Diale, Dineo, Kanakana-Katumba, Mukondeleli G, Maladzhi, Rendani W
- Authors: Diale, Dineo , Kanakana-Katumba, Mukondeleli G , Maladzhi, Rendani W
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450641 , vital:74970 , xlink:href="https://www.astesj.com/publications/ASTESJ_060145.pdf"
- Description: There are pressures to adopt sustainable behaviour more so in generating profits and benefiting the society to accelerate green efforts through a green framework. The overarching goal of the paper is premised through various works of literature, building the ecosystem the elements highlighted by most researchers in the field of environmental entrepreneurship. The various models reviewed consists of generic incubators and entrepreneurship, and societal and environmental factors. Environmental entrepreneurship is often used interchangeably with concepts such as green entrepreneurship and ecopreneurship which under-researched globally, with non-existent efforts on the applicability and modelling of key environmental entrepreneurship within a specific context utilising the system dynamics approach. In order to assess the environmental entrepreneurship ecosystem, the authors adopted a system dynamic approach to determine key variables that enable the development of the system. A literature review was conducted, and of the 135 articles reviewed, n= 92 peer-reviewed articles met the criteria that the researchers set. Some of the results emanating from a systematic review are environmental policy, green skills, financial and non-financial support, societal and behavioural factors, environmental agility, ethics and governance, and access to markets. The theoretical results are simulated using system dynamics modelling. Due to limited research on the abovementioned topic, a possible impacting variable (Exogenous variables) was broadened to add value to, and have an impact on, the study. Upon reviewing the above-mentioned models, the framework emerged signalling elements to be simulated in the system dynamics model, which were then theoretically contextualised for the South African context. The theoretical virtual system dynamic model forming part of the framework will be tested and validated in the next study. The applicability of the theoretical ecosystem to South African context as well as future recommendations are provided in the study.
- Full Text:
- Date Issued: 2021
- Authors: Diale, Dineo , Kanakana-Katumba, Mukondeleli G , Maladzhi, Rendani W
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450641 , vital:74970 , xlink:href="https://www.astesj.com/publications/ASTESJ_060145.pdf"
- Description: There are pressures to adopt sustainable behaviour more so in generating profits and benefiting the society to accelerate green efforts through a green framework. The overarching goal of the paper is premised through various works of literature, building the ecosystem the elements highlighted by most researchers in the field of environmental entrepreneurship. The various models reviewed consists of generic incubators and entrepreneurship, and societal and environmental factors. Environmental entrepreneurship is often used interchangeably with concepts such as green entrepreneurship and ecopreneurship which under-researched globally, with non-existent efforts on the applicability and modelling of key environmental entrepreneurship within a specific context utilising the system dynamics approach. In order to assess the environmental entrepreneurship ecosystem, the authors adopted a system dynamic approach to determine key variables that enable the development of the system. A literature review was conducted, and of the 135 articles reviewed, n= 92 peer-reviewed articles met the criteria that the researchers set. Some of the results emanating from a systematic review are environmental policy, green skills, financial and non-financial support, societal and behavioural factors, environmental agility, ethics and governance, and access to markets. The theoretical results are simulated using system dynamics modelling. Due to limited research on the abovementioned topic, a possible impacting variable (Exogenous variables) was broadened to add value to, and have an impact on, the study. Upon reviewing the above-mentioned models, the framework emerged signalling elements to be simulated in the system dynamics model, which were then theoretically contextualised for the South African context. The theoretical virtual system dynamic model forming part of the framework will be tested and validated in the next study. The applicability of the theoretical ecosystem to South African context as well as future recommendations are provided in the study.
- Full Text:
- Date Issued: 2021
Environmental ethics: A sourcebook for educators
- Jickling, Bob, Lotz-Sisitka, Heila, Olvitt, Lausanne L, O’Donoghue, Rob B, Schudel, Ingrid J, McGarry, Dylan K, Niblett, Blair
- Authors: Jickling, Bob , Lotz-Sisitka, Heila , Olvitt, Lausanne L , O’Donoghue, Rob B , Schudel, Ingrid J , McGarry, Dylan K , Niblett, Blair
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435834 , vital:73205 , ISBN 978-1991201287 , https://www.amazon.com/Environmental-Ethics-Sourcebook-Bob-Jickling/dp/1991201281
- Description: This well-constructed, and highly original, sourcebook inte-grates educational materials for teaching environmental eth-ics with theoretical reflections. The book is set to contribute immensely to its aim of taking ethics out of philosophy de-partments and putting it into the streets, into villages, and on the Earth—to make ethics an everyday activity, not some-thing left to experts and specialists. Context-based activities are presented in almost every chapter. While it acknowledg-es foundational theories in environmental ethics, and the work that they continue to do, it wholeheartedly embraces a growing body of literature that emphasises contextual, pro-cess-oriented, and place-based approaches to ethical reflec-tion, deliberation, and action. It walks on the ground and isn’t afraid to get a little dirty or to seek joy in earthly relationships. And it ultimately breaks with much Western academic tradi-tion by framing “ethics in a storied world”, thus making room to move beyond Euro-American perspectives in environmen-tal issues. This work will be of interest to school teachers and other non-formal and informal educators, teacher educators, college instructors, university professors, and other profes-sionals who wish to bring environmental ethics to the fore-front of their pedagogical practices.
- Full Text:
- Date Issued: 2021
- Authors: Jickling, Bob , Lotz-Sisitka, Heila , Olvitt, Lausanne L , O’Donoghue, Rob B , Schudel, Ingrid J , McGarry, Dylan K , Niblett, Blair
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435834 , vital:73205 , ISBN 978-1991201287 , https://www.amazon.com/Environmental-Ethics-Sourcebook-Bob-Jickling/dp/1991201281
- Description: This well-constructed, and highly original, sourcebook inte-grates educational materials for teaching environmental eth-ics with theoretical reflections. The book is set to contribute immensely to its aim of taking ethics out of philosophy de-partments and putting it into the streets, into villages, and on the Earth—to make ethics an everyday activity, not some-thing left to experts and specialists. Context-based activities are presented in almost every chapter. While it acknowledg-es foundational theories in environmental ethics, and the work that they continue to do, it wholeheartedly embraces a growing body of literature that emphasises contextual, pro-cess-oriented, and place-based approaches to ethical reflec-tion, deliberation, and action. It walks on the ground and isn’t afraid to get a little dirty or to seek joy in earthly relationships. And it ultimately breaks with much Western academic tradi-tion by framing “ethics in a storied world”, thus making room to move beyond Euro-American perspectives in environmen-tal issues. This work will be of interest to school teachers and other non-formal and informal educators, teacher educators, college instructors, university professors, and other profes-sionals who wish to bring environmental ethics to the fore-front of their pedagogical practices.
- Full Text:
- Date Issued: 2021
Epidemiology, risk factors and molecular analysis of carbapenem-resistant Enterobacteriaceae (CRE) in Mthatha, Eastern Cape, South Africa:
- S.D.Vasaikar, P.Hanise, D.T.Abaver
- Authors: S.D.Vasaikar , P.Hanise , D.T.Abaver
- Date: 2021
- Subjects: Epidemiology Carbapenem-resistant Enterobacteriaceae Mthatha
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3129 , vital:43143 , xlink:href="https://doi.org/10.3390/f10060467"
- Description: Abstract text. Background: The emergence of carbapenem resistance in Enterobacteriaceae is an important threat to global health. Reported outcomes of infections with carbapenem-resistant Enterobacteriaceae (CRE) are poor. Commonly used antibiotics are generally inactive against CRE. Therefore, timely detection of CRE is of paramount importance. This study aimed to investigate the resistance genes responsible for CRE in Mthatha and to identify risk factors. Methods and materials: Study design – Prospective cohort study. Study period – 23 April to 27 September 2019. Setting – Eastern Cape province, SA. Study population – All adult and paediatric CRE patients. CRE case definition according to CDC 2018. ID and AST-bioMérieux Vitek 2 system. Detection of the blaOXA-48, blaKPC, blaNDM, and blaVIM by the RESIST-4 OKNV assay (Coris). Patients were interviewed to determine risk factors associated with CRE. Results: Forty-four non-duplicate CRE patients were identified during the study period from microbiology lab at NMAH. Enterobacteriaceae species: K. pneumoniae 22 (61.4%), E. cloacae 10 (22.7%), E. coli 2 (4.5%) and K. oxytoca, P. rettgeri and M. morganii 1 each (4.3%). Adult patient 29 (65.9%0 and paediatric 15 (34.1%). Race: all black patients except one white. CRE genes-blaOXA-48 22 (50%), blaNDM 8 (18.2%), two isolates (4.5%) with both blaOXA and blaNDM. We did not find any blaKPC and blaVIM in our setting and 12 (27.2%) isolates were negative for all OKNV. Outcomes: Demised 18 (40.9%), still admitted in the ward 1 (2.3%), discharged home on basis of clinical grounds 22 (50%) and 3 (6.8%) were transferred back to the district hospitals. HAI in 27 (61.4%) with VAP 8, HABSI 8, CAUTI 5, SSI 3 and CLABSI in 3. Risk factors for CRE acquisition were antibiotic exposure 25 (58.7%), ICU stay 7 (15.9%), received medical care in last 6 months 35 (79.6%) and none travelled outside RSA. HIV positive – 19 (43.2%). Conclusion: In out setting our CRE mortality rate is 40.9%, common CRE genotypes are blaOXA-48 and blaNDM. K. pneumoniae is the most common CRE-producing Enterobacteriaceae and antibiotic exposure is an important risk factor in Mthatha and surrounding areas.
- Full Text:
- Date Issued: 2021
- Authors: S.D.Vasaikar , P.Hanise , D.T.Abaver
- Date: 2021
- Subjects: Epidemiology Carbapenem-resistant Enterobacteriaceae Mthatha
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3129 , vital:43143 , xlink:href="https://doi.org/10.3390/f10060467"
- Description: Abstract text. Background: The emergence of carbapenem resistance in Enterobacteriaceae is an important threat to global health. Reported outcomes of infections with carbapenem-resistant Enterobacteriaceae (CRE) are poor. Commonly used antibiotics are generally inactive against CRE. Therefore, timely detection of CRE is of paramount importance. This study aimed to investigate the resistance genes responsible for CRE in Mthatha and to identify risk factors. Methods and materials: Study design – Prospective cohort study. Study period – 23 April to 27 September 2019. Setting – Eastern Cape province, SA. Study population – All adult and paediatric CRE patients. CRE case definition according to CDC 2018. ID and AST-bioMérieux Vitek 2 system. Detection of the blaOXA-48, blaKPC, blaNDM, and blaVIM by the RESIST-4 OKNV assay (Coris). Patients were interviewed to determine risk factors associated with CRE. Results: Forty-four non-duplicate CRE patients were identified during the study period from microbiology lab at NMAH. Enterobacteriaceae species: K. pneumoniae 22 (61.4%), E. cloacae 10 (22.7%), E. coli 2 (4.5%) and K. oxytoca, P. rettgeri and M. morganii 1 each (4.3%). Adult patient 29 (65.9%0 and paediatric 15 (34.1%). Race: all black patients except one white. CRE genes-blaOXA-48 22 (50%), blaNDM 8 (18.2%), two isolates (4.5%) with both blaOXA and blaNDM. We did not find any blaKPC and blaVIM in our setting and 12 (27.2%) isolates were negative for all OKNV. Outcomes: Demised 18 (40.9%), still admitted in the ward 1 (2.3%), discharged home on basis of clinical grounds 22 (50%) and 3 (6.8%) were transferred back to the district hospitals. HAI in 27 (61.4%) with VAP 8, HABSI 8, CAUTI 5, SSI 3 and CLABSI in 3. Risk factors for CRE acquisition were antibiotic exposure 25 (58.7%), ICU stay 7 (15.9%), received medical care in last 6 months 35 (79.6%) and none travelled outside RSA. HIV positive – 19 (43.2%). Conclusion: In out setting our CRE mortality rate is 40.9%, common CRE genotypes are blaOXA-48 and blaNDM. K. pneumoniae is the most common CRE-producing Enterobacteriaceae and antibiotic exposure is an important risk factor in Mthatha and surrounding areas.
- Full Text:
- Date Issued: 2021
Ethnobotanical survey, phytoconstituents and antibacterial investigation of Rapanea melanophloeos (L.) Mez. bark, fruit and leaf extracts
- Lukhele, Thabile, Olivier, Denise, Tata, Charlotte, Ikhile, Monisola I, Krause, Rui W M, van Vuuren, Sandy, Ndineh, Derek T
- Authors: Lukhele, Thabile , Olivier, Denise , Tata, Charlotte , Ikhile, Monisola I , Krause, Rui W M , van Vuuren, Sandy , Ndineh, Derek T
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191791 , vital:45164 , xlink:href="https://doi.org/10.1515/psr-2020-0143"
- Description: Rapanea melanophloeos is traditionally used in South Africa in the treatment of ailments of the skin, pulmonary and gastro intestinal tract. This study was aimed at giving an overview of these traditional uses and comparing the phytochemicals and antibacterial activities of various crude extracts of the leaves, fruits and bark in order to validate these uses. The three plant parts were extracted using petroleum ether (PE), ethyl acetate (EtOAc), methanol (MeOH) and water. Various phytochemicals were compared using TLC, while alcohol precipitable solids (APS), non-polar terpenes and amino acids were analysed by GC-MS. Antibacterial activity was determined against three Gram-positive and three Gram-negative strains by microdilution assays. Caryophyllene oxides, α-cadinol and (−)-spathulenol were identified in the PE extracts. All nine essential amino acids were present in fruit extracts in significantly higher levels than in the leaves and bark; 255.1, 23.4 and 21.3 mg/g respectively. Most of the extracts showed good antibacterial activity, especially against the Gram-positive pathogens (MIC of ≤1 mg/mL), the EtOAc extracts exhibited the best activity with the fruit having an MIC values of 0.1 ± 0.2 mg/mL against Staphylococcus epidermidis and Enterococcus faecalis, 0.05 mg/mL against Bacillus cereus. Results from this study validate the ethnomedicinal uses of R. melanophloeos extracts for ailments of bacterial etiology. The plant had a rich supply of secondary metabolites, APS and amino acids and TLC and antibacterial activities of the extracts showed slight variations in chemical composition due to geographic distribution.
- Full Text:
- Date Issued: 2021
- Authors: Lukhele, Thabile , Olivier, Denise , Tata, Charlotte , Ikhile, Monisola I , Krause, Rui W M , van Vuuren, Sandy , Ndineh, Derek T
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191791 , vital:45164 , xlink:href="https://doi.org/10.1515/psr-2020-0143"
- Description: Rapanea melanophloeos is traditionally used in South Africa in the treatment of ailments of the skin, pulmonary and gastro intestinal tract. This study was aimed at giving an overview of these traditional uses and comparing the phytochemicals and antibacterial activities of various crude extracts of the leaves, fruits and bark in order to validate these uses. The three plant parts were extracted using petroleum ether (PE), ethyl acetate (EtOAc), methanol (MeOH) and water. Various phytochemicals were compared using TLC, while alcohol precipitable solids (APS), non-polar terpenes and amino acids were analysed by GC-MS. Antibacterial activity was determined against three Gram-positive and three Gram-negative strains by microdilution assays. Caryophyllene oxides, α-cadinol and (−)-spathulenol were identified in the PE extracts. All nine essential amino acids were present in fruit extracts in significantly higher levels than in the leaves and bark; 255.1, 23.4 and 21.3 mg/g respectively. Most of the extracts showed good antibacterial activity, especially against the Gram-positive pathogens (MIC of ≤1 mg/mL), the EtOAc extracts exhibited the best activity with the fruit having an MIC values of 0.1 ± 0.2 mg/mL against Staphylococcus epidermidis and Enterococcus faecalis, 0.05 mg/mL against Bacillus cereus. Results from this study validate the ethnomedicinal uses of R. melanophloeos extracts for ailments of bacterial etiology. The plant had a rich supply of secondary metabolites, APS and amino acids and TLC and antibacterial activities of the extracts showed slight variations in chemical composition due to geographic distribution.
- Full Text:
- Date Issued: 2021
Evaluating and reflecting on coproduction of protected area management plans
- Roux, Dirk J, Nel, Jeanne L, Freitag, Stefanie, Novellie, Peter, Rosenberg, Eureta
- Authors: Roux, Dirk J , Nel, Jeanne L , Freitag, Stefanie , Novellie, Peter , Rosenberg, Eureta
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370550 , vital:66353 , xlink:href="https://doi.org/10.1111/csp2.542"
- Description: Protected areas are complex social-ecological systems, hence their management should be guided by engagement and co-learning with diverse stakeholders. The challenge of effective stakeholder participation has generated a body of literature on the design and facilitation of coproduction processes. In this study, we used this literature to develop a principle-based framework for assessing coproduction. We then applied this framework to evaluate how well “adaptive planning” (a sub-process of adaptive management used for visioning and objective setting with stakeholders), as applied to the Garden Route National Park in South Africa, aligned with the ideals of coproduction. Our analysis revealed shortcomings in the adaptive planning process, which could be improved through broadening the agenda beyond the mandate and control of national parks, empowering collective agency among a wider stakeholder network, and embedding co-learning with stakeholders as an ongoing journey. A significant finding was that adaptive management does not align well with the ideals of coproduction, which may be better supported by an adaptive comanagement approach. The latter is particularly necessary in complex national parks that are diverse in terms of both ecosystems and stakeholders, and where governance may be contested.
- Full Text:
- Date Issued: 2021
- Authors: Roux, Dirk J , Nel, Jeanne L , Freitag, Stefanie , Novellie, Peter , Rosenberg, Eureta
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370550 , vital:66353 , xlink:href="https://doi.org/10.1111/csp2.542"
- Description: Protected areas are complex social-ecological systems, hence their management should be guided by engagement and co-learning with diverse stakeholders. The challenge of effective stakeholder participation has generated a body of literature on the design and facilitation of coproduction processes. In this study, we used this literature to develop a principle-based framework for assessing coproduction. We then applied this framework to evaluate how well “adaptive planning” (a sub-process of adaptive management used for visioning and objective setting with stakeholders), as applied to the Garden Route National Park in South Africa, aligned with the ideals of coproduction. Our analysis revealed shortcomings in the adaptive planning process, which could be improved through broadening the agenda beyond the mandate and control of national parks, empowering collective agency among a wider stakeholder network, and embedding co-learning with stakeholders as an ongoing journey. A significant finding was that adaptive management does not align well with the ideals of coproduction, which may be better supported by an adaptive comanagement approach. The latter is particularly necessary in complex national parks that are diverse in terms of both ecosystems and stakeholders, and where governance may be contested.
- Full Text:
- Date Issued: 2021
Evaluating Community Engagement Strategies to Manage Stigma in Two African Genomics Studies Involving People Living with Schizophrenia or Rheumatic Heart Disease
- Campbell, Megan, Matshabane, Olivia P, Mqulwana, Sibonile, Mndini, Michael, Nagdee, Mohamed, Stein, Dan J, de Vries, Jantina
- Authors: Campbell, Megan , Matshabane, Olivia P , Mqulwana, Sibonile , Mndini, Michael , Nagdee, Mohamed , Stein, Dan J , de Vries, Jantina
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302475 , vital:58199 , xlink:href="https://doi.org/10.1155/2021/9926495"
- Description: In global health research and genomics research specifically, community engagement has gained prominence in enhancing ethical conduct, particularly in managing the risk of stigmatization, but there is minimal scientific evidence on how to do this effectively. This article reports on community engagement evaluation strategies in two African genomics studies: the Stigma in African Genomics Research study and the Genomics of Schizophrenia in South African Xhosa People (SAX) study. Within the Stigma in African Genomics Research study, a self-report rating scale and open-ended questions were used to track participant responses to an experiential theatre workshop. The workshop focused on participant experiences of living with schizophrenia or rheumatic heart disease (RHD). While the schizophrenia group reported more alienation and less stigma resistance than the RHD group, both groups demonstrated increased stigma resistance over time, after participating in the workshops. Hearing from others living with and managing the same illness normalised participants’ own experiences and encouraged them. Within the SAX study, a short rating scale and qualitative feedback methods were used to evaluate a Mental Health Literacy Day targeting mental health stigma. Information talks about (i) the symptoms of schizophrenia and treatment options and (ii) the illness experiences of a patient in recovery were rated as the most helpful on the day. Audience members reported that these talks challenged negative perceptions about severe mental illness. Three important learnings emerged from these evaluations: firstly, integration of evaluation strategies at the research study planning phase is likely to promote more effective community engagement. Secondly, a combination of quantitative and qualitative methods that draw on simple descriptive statistics and thematic analysis can provide nuanced perspectives about the value of community engagement. Thirdly, such evidence is necessary in establishing and promoting the science of community engagement in genomics research and health research more broadly.
- Full Text:
- Date Issued: 2021
- Authors: Campbell, Megan , Matshabane, Olivia P , Mqulwana, Sibonile , Mndini, Michael , Nagdee, Mohamed , Stein, Dan J , de Vries, Jantina
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302475 , vital:58199 , xlink:href="https://doi.org/10.1155/2021/9926495"
- Description: In global health research and genomics research specifically, community engagement has gained prominence in enhancing ethical conduct, particularly in managing the risk of stigmatization, but there is minimal scientific evidence on how to do this effectively. This article reports on community engagement evaluation strategies in two African genomics studies: the Stigma in African Genomics Research study and the Genomics of Schizophrenia in South African Xhosa People (SAX) study. Within the Stigma in African Genomics Research study, a self-report rating scale and open-ended questions were used to track participant responses to an experiential theatre workshop. The workshop focused on participant experiences of living with schizophrenia or rheumatic heart disease (RHD). While the schizophrenia group reported more alienation and less stigma resistance than the RHD group, both groups demonstrated increased stigma resistance over time, after participating in the workshops. Hearing from others living with and managing the same illness normalised participants’ own experiences and encouraged them. Within the SAX study, a short rating scale and qualitative feedback methods were used to evaluate a Mental Health Literacy Day targeting mental health stigma. Information talks about (i) the symptoms of schizophrenia and treatment options and (ii) the illness experiences of a patient in recovery were rated as the most helpful on the day. Audience members reported that these talks challenged negative perceptions about severe mental illness. Three important learnings emerged from these evaluations: firstly, integration of evaluation strategies at the research study planning phase is likely to promote more effective community engagement. Secondly, a combination of quantitative and qualitative methods that draw on simple descriptive statistics and thematic analysis can provide nuanced perspectives about the value of community engagement. Thirdly, such evidence is necessary in establishing and promoting the science of community engagement in genomics research and health research more broadly.
- Full Text:
- Date Issued: 2021
Evaluating the cyber security skills gap relating to penetration testing
- Authors: Beukes, Dirk Johannes
- Date: 2021
- Subjects: Computer networks -- Security measures , Computer networks -- Monitoring , Computer networks -- Management , Data protection , Information technology -- Security measures , Professionals -- Supply and demand , Electronic data personnel -- Supply and demand
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/171120 , vital:42021
- Description: Information Technology (IT) is growing rapidly and has become an integral part of daily life. It provides a boundless list of services and opportunities, generating boundless sources of information, which could be abused or exploited. Due to this growth, there are thousands of new users added to the grid using computer systems in a static and mobile environment; this fact alone creates endless volumes of data to be exploited and hardware devices to be abused by the wrong people. The growth in the IT environment adds challenges that may affect users in their personal, professional, and business lives. There are constant threats on corporate and private computer networks and computer systems. In the corporate environment companies try to eliminate the threat by testing networks making use of penetration tests and by implementing cyber awareness programs to make employees more aware of the cyber threat. Penetration tests and vulnerability assessments are undervalued; are seen as a formality and are not used to increase system security. If used regularly the computer system will be more secure and attacks minimized. With the growth in technology, industries all over the globe become fully dependent on information systems in doing their day-to-day business. As technology evolves and new technology becomes available, the bigger the risk becomes to protect against the dangers which come with this new technology. For industry to protect itself against this growth in technology, personnel with a certain skill set is needed. This is where cyber security plays a very important role in the protection of information systems to ensure the confidentiality, integrity and availability of the information system itself and the data on the system. Due to this drive to secure information systems, the need for cyber security by professionals is on the rise as well. It is estimated that there is a shortage of one million cyber security professionals globally. What is the reason for this skills shortage? Will it be possible to close this skills shortage gap? This study is about identifying the skills gap and identifying possible ways to close this skills gap. In this study, research was conducted on the cyber security international standards, cyber security training at universities and international certification focusing specifically on penetration testing, the evaluation of the need of industry while recruiting new penetration testers, finishing with suggestions on how to fill possible gaps in the skills market with a conclusion.
- Full Text:
- Date Issued: 2021
- Authors: Beukes, Dirk Johannes
- Date: 2021
- Subjects: Computer networks -- Security measures , Computer networks -- Monitoring , Computer networks -- Management , Data protection , Information technology -- Security measures , Professionals -- Supply and demand , Electronic data personnel -- Supply and demand
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/171120 , vital:42021
- Description: Information Technology (IT) is growing rapidly and has become an integral part of daily life. It provides a boundless list of services and opportunities, generating boundless sources of information, which could be abused or exploited. Due to this growth, there are thousands of new users added to the grid using computer systems in a static and mobile environment; this fact alone creates endless volumes of data to be exploited and hardware devices to be abused by the wrong people. The growth in the IT environment adds challenges that may affect users in their personal, professional, and business lives. There are constant threats on corporate and private computer networks and computer systems. In the corporate environment companies try to eliminate the threat by testing networks making use of penetration tests and by implementing cyber awareness programs to make employees more aware of the cyber threat. Penetration tests and vulnerability assessments are undervalued; are seen as a formality and are not used to increase system security. If used regularly the computer system will be more secure and attacks minimized. With the growth in technology, industries all over the globe become fully dependent on information systems in doing their day-to-day business. As technology evolves and new technology becomes available, the bigger the risk becomes to protect against the dangers which come with this new technology. For industry to protect itself against this growth in technology, personnel with a certain skill set is needed. This is where cyber security plays a very important role in the protection of information systems to ensure the confidentiality, integrity and availability of the information system itself and the data on the system. Due to this drive to secure information systems, the need for cyber security by professionals is on the rise as well. It is estimated that there is a shortage of one million cyber security professionals globally. What is the reason for this skills shortage? Will it be possible to close this skills shortage gap? This study is about identifying the skills gap and identifying possible ways to close this skills gap. In this study, research was conducted on the cyber security international standards, cyber security training at universities and international certification focusing specifically on penetration testing, the evaluation of the need of industry while recruiting new penetration testers, finishing with suggestions on how to fill possible gaps in the skills market with a conclusion.
- Full Text:
- Date Issued: 2021
Evaluation of metallophthalocyanine functionalized photocatalytic asymmetric polymer membranes for pollution control and antimicrobial activity
- Mafukidze, Donovan Musizvinoda Chidyamurimi
- Authors: Mafukidze, Donovan Musizvinoda Chidyamurimi
- Date: 2021
- Subjects: Photosensitizing compounds , Water -- Purification -- Photocatalysis , Phthalocyanines , Polymeric membranes , Porphyrins
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/171357 , vital:42052 , 10.21504/10962/171357
- Description: The conceptualisation of photosensitizing water treatment polymer membranes using phthalocyanine based photosensitizers is reported in this thesis. The key to successful preparation of stable photoactive polymer membranes was established as the covalent anchorage of the photosensitizer to a polymer, which was proven by singlet oxygen generation by the membranes without photosensitizer deterioration. Despite this limitation, the covalent linkage-incapable unsubstituted zinc (II) phthalocyanine (complex 2) was applied as a nanoconjugate of graphene quantum dots (2π(GQDs)). 2π(GQDs) was formed through π-π stacking, and was then covalently anchored, as a proof of concept. This concept was also applied to 2-(4-carboxyphenoxy) phthalocyaninato zinc (II) (complex 3) which is capable of covalent linkage but proved to deteriorate the efficiency of singlet oxygen formation with comparison to the covalent conjugates. Singlet oxygen generation by functionalized polymer membranes rendered them photocatalytic in the degradation of organic pollutants and microorganisms in water. Organic pollutant degradation capability was exemplified by 2π(GQDs) and a porphyrin-phthalocyanine heterodyad (complex 10) functionalized membranes (2π(GQDs)-memb and 10-memb respectively), where a MPc loading of approximately 0.139 μmol MPc/g of membrane was able to achieve a 4-chlorophenol degradation rate of 3.77 × 10−6 mol L−1 min−1 in a second order reaction with an initial 4-chlorophenol concentration of 3.24 × 10−4 mol L−1 for 2π(GQDs)-memb as an example. Antibacterial studies against S.aureus using a quaternized MPc and conjugates of silver triangular nanoprisms with zinc (II) and indium (III) MPcs showed note-worthy improvements in photodynamic antimicrobial chemotherapy (PACT) activity in comparison to the unquaternized MPc precursor, and the free zinc and indium MPcs respectively. Functionalization of polymer membranes with these higher activity photosensitizers translated to the formation of potentially superior biological fouling resistant membranes. The use of porphyrin-phthalocyanine polynuclei arrays (complex 10) in polymer membrane functionalization resulted in the use of a wider wavelength range (white light). The findings from this work as a whole, thus presents the potential applicability of phthalocyanine functionalized polymer membranes in water treatment technology.
- Full Text:
- Date Issued: 2021
- Authors: Mafukidze, Donovan Musizvinoda Chidyamurimi
- Date: 2021
- Subjects: Photosensitizing compounds , Water -- Purification -- Photocatalysis , Phthalocyanines , Polymeric membranes , Porphyrins
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/171357 , vital:42052 , 10.21504/10962/171357
- Description: The conceptualisation of photosensitizing water treatment polymer membranes using phthalocyanine based photosensitizers is reported in this thesis. The key to successful preparation of stable photoactive polymer membranes was established as the covalent anchorage of the photosensitizer to a polymer, which was proven by singlet oxygen generation by the membranes without photosensitizer deterioration. Despite this limitation, the covalent linkage-incapable unsubstituted zinc (II) phthalocyanine (complex 2) was applied as a nanoconjugate of graphene quantum dots (2π(GQDs)). 2π(GQDs) was formed through π-π stacking, and was then covalently anchored, as a proof of concept. This concept was also applied to 2-(4-carboxyphenoxy) phthalocyaninato zinc (II) (complex 3) which is capable of covalent linkage but proved to deteriorate the efficiency of singlet oxygen formation with comparison to the covalent conjugates. Singlet oxygen generation by functionalized polymer membranes rendered them photocatalytic in the degradation of organic pollutants and microorganisms in water. Organic pollutant degradation capability was exemplified by 2π(GQDs) and a porphyrin-phthalocyanine heterodyad (complex 10) functionalized membranes (2π(GQDs)-memb and 10-memb respectively), where a MPc loading of approximately 0.139 μmol MPc/g of membrane was able to achieve a 4-chlorophenol degradation rate of 3.77 × 10−6 mol L−1 min−1 in a second order reaction with an initial 4-chlorophenol concentration of 3.24 × 10−4 mol L−1 for 2π(GQDs)-memb as an example. Antibacterial studies against S.aureus using a quaternized MPc and conjugates of silver triangular nanoprisms with zinc (II) and indium (III) MPcs showed note-worthy improvements in photodynamic antimicrobial chemotherapy (PACT) activity in comparison to the unquaternized MPc precursor, and the free zinc and indium MPcs respectively. Functionalization of polymer membranes with these higher activity photosensitizers translated to the formation of potentially superior biological fouling resistant membranes. The use of porphyrin-phthalocyanine polynuclei arrays (complex 10) in polymer membrane functionalization resulted in the use of a wider wavelength range (white light). The findings from this work as a whole, thus presents the potential applicability of phthalocyanine functionalized polymer membranes in water treatment technology.
- Full Text:
- Date Issued: 2021