Organosilicon compounds as fluorescent chemosensors for fluoride anion recognition
- Gai, Lizhi, Mack, John, Lu, Hua, Nyokong, Tebello, Li, Zhifang, Kobayashi, Nagao, Shen, Zhen
- Authors: Gai, Lizhi , Mack, John , Lu, Hua , Nyokong, Tebello , Li, Zhifang , Kobayashi, Nagao , Shen, Zhen
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241424 , vital:50938 , xlink:href="https://doi.org/10.1016/j.ccr.2014.10.009"
- Description: Recent developments in organosilicon-based chemosensors for F− recognition are reviewed. The design strategies for improving the photophysical properties of organosilicon-based chemosensors are elaborated, with an emphasis placed on their utility for biological applications. The photophysical properties and electronic structures are analyzed in depth with reference made to the results of molecular modeling calculation and possible future research directions are assessed.
- Full Text:
- Date Issued: 2015
- Authors: Gai, Lizhi , Mack, John , Lu, Hua , Nyokong, Tebello , Li, Zhifang , Kobayashi, Nagao , Shen, Zhen
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241424 , vital:50938 , xlink:href="https://doi.org/10.1016/j.ccr.2014.10.009"
- Description: Recent developments in organosilicon-based chemosensors for F− recognition are reviewed. The design strategies for improving the photophysical properties of organosilicon-based chemosensors are elaborated, with an emphasis placed on their utility for biological applications. The photophysical properties and electronic structures are analyzed in depth with reference made to the results of molecular modeling calculation and possible future research directions are assessed.
- 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
The development visions and attitudes towards urban forestry of officials responsible for greening in South African towns
- Gwedla, Nanamhla, Shackleton, Charlie M
- Authors: Gwedla, Nanamhla , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180856 , vital:43651 , xlink:href="https://doi.org/10.1016/j.landusepol.2014.07.004"
- Description: The planting and maintenance of trees in public areas of South African towns is the responsibility of local municipalities. Therefore, it is necessary to appreciate the visions and attitudes of municipal officials and decision-makers in charge of such activities for an understanding of the distribution and abundance of trees along streets and in urban green spaces. We hypothesised that the town size and relative wealth and current extent of trees in public places would influence the visions of such officials. We therefore conducted 24 semi-structured interviews with the officials responsible for urban tree planting in 24 towns in the Eastern Cape province, whilst also assessing the abundance of street trees via GIS counts. The density of street trees was variable, ranging from 0.5 to 9.5 trees/ha. There were significantly positive relationships between town size, relative wealth measures and street tree density. Several of the managers did not include environmental issues or trees in vision of the future for their town, although most did. There was no relationship between the managers’ visions for the future and attitudes and current street tree density. Most of the managers experienced several constraints in trying to implement their vision, notably a lack of funds for urban forestry, limited space for tree planting in low-cost housing developments, vandalism, and lack of skilled personnel.
- Full Text:
- Date Issued: 2015
- Authors: Gwedla, Nanamhla , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180856 , vital:43651 , xlink:href="https://doi.org/10.1016/j.landusepol.2014.07.004"
- Description: The planting and maintenance of trees in public areas of South African towns is the responsibility of local municipalities. Therefore, it is necessary to appreciate the visions and attitudes of municipal officials and decision-makers in charge of such activities for an understanding of the distribution and abundance of trees along streets and in urban green spaces. We hypothesised that the town size and relative wealth and current extent of trees in public places would influence the visions of such officials. We therefore conducted 24 semi-structured interviews with the officials responsible for urban tree planting in 24 towns in the Eastern Cape province, whilst also assessing the abundance of street trees via GIS counts. The density of street trees was variable, ranging from 0.5 to 9.5 trees/ha. There were significantly positive relationships between town size, relative wealth measures and street tree density. Several of the managers did not include environmental issues or trees in vision of the future for their town, although most did. There was no relationship between the managers’ visions for the future and attitudes and current street tree density. Most of the managers experienced several constraints in trying to implement their vision, notably a lack of funds for urban forestry, limited space for tree planting in low-cost housing developments, vandalism, and lack of skilled personnel.
- Full Text:
- Date Issued: 2015
The benefits from and barriers to participation in civic environmental organisations in South Africa
- Higgins, Olivia, Shackleton, Charlie M
- Authors: Higgins, Olivia , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180813 , vital:43648 , xlink:href="https://doi.org/10.1007/s10531-015-0924-6"
- Description: With growing global public awareness of a wide range of conservation and environmental issues, environmental volunteerism is increasing. In order to attract and retain volunteers, it is useful to understand what benefits they hope for as well as the barriers that hinder their participation. Here we examine the benefits from and barriers to participation in 26 conservation and environmental civic organisations in South Africa, categorised by their primary mission as botanical, wildlife or green. Questionnaires were sent to volunteers on the mailing list of each civic organisation (and 66 responses received), supplemented with direct interviews with key staff and five focus group discussions. There were differences in the perception of benefits obtained and barriers experienced by volunteers between the three groups. Respondents from botanical and green civic organisations rated enjoyment of the task as the primary benefit, whereas the most common response amongst wildlife organisation volunteers was a higher level of life satisfaction. Lack of time was a major barrier across all groups, whilst lack of communication between organisers and volunteers was mentioned frequently by volunteers in wildlife and green organisations. The mean number of hours offered per volunteer was significantly higher amongst wildlife organisations than either botanical or green ones, but for all three, the value of volunteer contributions was, at several millions of rand annually, substantial. There was no relationship between the number of perceived benefits and the number of hours volunteered. This study indicates that motivations and barriers differ amongst volunteers, which is important to acknowledge in attracting and optimising the contributions of conservation and environmental volunteers.
- Full Text:
- Date Issued: 2015
The benefits from and barriers to participation in civic environmental organisations in South Africa
- Authors: Higgins, Olivia , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180813 , vital:43648 , xlink:href="https://doi.org/10.1007/s10531-015-0924-6"
- Description: With growing global public awareness of a wide range of conservation and environmental issues, environmental volunteerism is increasing. In order to attract and retain volunteers, it is useful to understand what benefits they hope for as well as the barriers that hinder their participation. Here we examine the benefits from and barriers to participation in 26 conservation and environmental civic organisations in South Africa, categorised by their primary mission as botanical, wildlife or green. Questionnaires were sent to volunteers on the mailing list of each civic organisation (and 66 responses received), supplemented with direct interviews with key staff and five focus group discussions. There were differences in the perception of benefits obtained and barriers experienced by volunteers between the three groups. Respondents from botanical and green civic organisations rated enjoyment of the task as the primary benefit, whereas the most common response amongst wildlife organisation volunteers was a higher level of life satisfaction. Lack of time was a major barrier across all groups, whilst lack of communication between organisers and volunteers was mentioned frequently by volunteers in wildlife and green organisations. The mean number of hours offered per volunteer was significantly higher amongst wildlife organisations than either botanical or green ones, but for all three, the value of volunteer contributions was, at several millions of rand annually, substantial. There was no relationship between the number of perceived benefits and the number of hours volunteered. This study indicates that motivations and barriers differ amongst volunteers, which is important to acknowledge in attracting and optimising the contributions of conservation and environmental volunteers.
- Full Text:
- Date Issued: 2015
Comparisons of isotopic niche widths of some invasive and indigenous fauna in a South African river
- Hill, Jaclyn M, Jones, Roy W, Hill, Martin P, Weyl, Olaf L F
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Date Issued: 2015
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Date Issued: 2015
Integrating local knowledge and forest surveys to assess Lantana camara impacts on indigenous species recruitment in Mazeppa Bay, South Africa
- Jevon, Tui, Shackleton, Charlie M
- Authors: Jevon, Tui , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180843 , vital:43650 , xlink:href="https://doi.org/10.1007/s10745-015-9748-y"
- Description: Invasive alien species have variable impacts on peoples’ livelihoods, plant communities and species at the local scale. Local people often have deeper insights into and experiences of these impacts than can be measured by scientific surveys. Here we examine the impacts of Lantana camara on the recruitment of indigenous forest species, many of which are used by local people. We integrate findings from conversations with elderly respondents with standard ecological surveys. Both sources of information indicate that the increasing presence of Lantana suppresses the number and species richness of recruits of indigenous forest species, which may retard forest succession. Dense thickets of Lantana also restricted access to non-timber forest products and species of cultural significance. The origin and date of the Lantana introduction in the area was identified by respondents as the 1960s and it escaped into the wild in the early 1970s. These findings can be incorporated into locally based management considerations.
- Full Text:
- Date Issued: 2015
- Authors: Jevon, Tui , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180843 , vital:43650 , xlink:href="https://doi.org/10.1007/s10745-015-9748-y"
- Description: Invasive alien species have variable impacts on peoples’ livelihoods, plant communities and species at the local scale. Local people often have deeper insights into and experiences of these impacts than can be measured by scientific surveys. Here we examine the impacts of Lantana camara on the recruitment of indigenous forest species, many of which are used by local people. We integrate findings from conversations with elderly respondents with standard ecological surveys. Both sources of information indicate that the increasing presence of Lantana suppresses the number and species richness of recruits of indigenous forest species, which may retard forest succession. Dense thickets of Lantana also restricted access to non-timber forest products and species of cultural significance. The origin and date of the Lantana introduction in the area was identified by respondents as the 1960s and it escaped into the wild in the early 1970s. These findings can be incorporated into locally based management considerations.
- Full Text:
- Date Issued: 2015
Wisdom as an aim of higher education
- Authors: Jones, Ward E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275765 , vital:55077 , xlink:href="https://doi.org/10.1007/s10790-014-9443-z"
- Description: A central concern of theoretical speculation about education is the kind of epistemic states that education can and should aim to achieve. One such epistemic state, long neglected in both education theory and philosophy, is wisdom. Might wisdom be something that educators should aim for? And might it be something that their students can achieve? My answer will be a qualified yes.
- Full Text:
- Date Issued: 2015
- Authors: Jones, Ward E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275765 , vital:55077 , xlink:href="https://doi.org/10.1007/s10790-014-9443-z"
- Description: A central concern of theoretical speculation about education is the kind of epistemic states that education can and should aim to achieve. One such epistemic state, long neglected in both education theory and philosophy, is wisdom. Might wisdom be something that educators should aim for? And might it be something that their students can achieve? My answer will be a qualified yes.
- Full Text:
- Date Issued: 2015
The politics of philosophy in Africa
- Jones, Ward E, Metz, Thaddeus
- Authors: Jones, Ward E , Metz, Thaddeus
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275733 , vital:55074 , xlink:href="https://doi.org/10.1080/02580136.2015.1104797"
- Description: The background to the present discussion is the prevalence of political and personal criticisms in philosophical discussions about Africa. As philosophers in South Africa—both white and black—continue to philosophise seriously about Africa, responses to their work sometimes take the form of political and personal criticisms of, if not attacks on, the philosopher exploring and defending considerations about the African continent. One of us (TM) has been the target of such critiques in light of his work. Our aim in this conversation is not to diminish or deflect such critiques. On the contrary, our aim is to understand them, to make them as strong as possible, and to bring them into the cooler realm of philosophical discussion.
- Full Text:
- Date Issued: 2015
- Authors: Jones, Ward E , Metz, Thaddeus
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275733 , vital:55074 , xlink:href="https://doi.org/10.1080/02580136.2015.1104797"
- Description: The background to the present discussion is the prevalence of political and personal criticisms in philosophical discussions about Africa. As philosophers in South Africa—both white and black—continue to philosophise seriously about Africa, responses to their work sometimes take the form of political and personal criticisms of, if not attacks on, the philosopher exploring and defending considerations about the African continent. One of us (TM) has been the target of such critiques in light of his work. Our aim in this conversation is not to diminish or deflect such critiques. On the contrary, our aim is to understand them, to make them as strong as possible, and to bring them into the cooler realm of philosophical discussion.
- Full Text:
- Date Issued: 2015
Venerating death
- Authors: Jones, Ward E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275749 , vital:55076 , xlink:href="https://doi.org/10.1080/05568641.2015.1014540"
- Description: In this paper, I am concerned with elucidating and expanding our attitudes toward our own death. As it is, our common attitudes toward our death are the following: we fear our premature death, and we dread our inevitable death. These attitudes are rational, but I want to argue that our attitudes toward death should be more complicated than this. A condition upon our value, our preciousness, as creatures is that we are vulnerable, and our vulnerability is, at bottom, a vulnerability to death. A corollary of this is that we could not be loved, either by ourselves or by others, for one cannot love—be concerned for—a being invulnerable to death. As a consequence, death plays a deep and abiding role in our value systems. Our susceptibility to premature and inevitable death is a condition upon our being valuable creatures and, in turn, it is a condition upon our being loved. Given the high value that we place on being valuable creatures who deserve love, we should equally place a high value on the constitutive conditions for being precious and loved. If, as I suggest, one of these conditions is that we will die, we should see our deaths not simply as something to fear or dread, but as something of great importance in our lives. Our deaths should be treated with awe, respect, and even praise.
- Full Text:
- Date Issued: 2015
- Authors: Jones, Ward E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275749 , vital:55076 , xlink:href="https://doi.org/10.1080/05568641.2015.1014540"
- Description: In this paper, I am concerned with elucidating and expanding our attitudes toward our own death. As it is, our common attitudes toward our death are the following: we fear our premature death, and we dread our inevitable death. These attitudes are rational, but I want to argue that our attitudes toward death should be more complicated than this. A condition upon our value, our preciousness, as creatures is that we are vulnerable, and our vulnerability is, at bottom, a vulnerability to death. A corollary of this is that we could not be loved, either by ourselves or by others, for one cannot love—be concerned for—a being invulnerable to death. As a consequence, death plays a deep and abiding role in our value systems. Our susceptibility to premature and inevitable death is a condition upon our being valuable creatures and, in turn, it is a condition upon our being loved. Given the high value that we place on being valuable creatures who deserve love, we should equally place a high value on the constitutive conditions for being precious and loved. If, as I suggest, one of these conditions is that we will die, we should see our deaths not simply as something to fear or dread, but as something of great importance in our lives. Our deaths should be treated with awe, respect, and even praise.
- Full Text:
- Date Issued: 2015
The direct-use value of urban tree non-timber forest products to household income in poorer suburbs in South African towns
- Kaoma, Humphrey, Shackleton, Charlie M
- Authors: Kaoma, Humphrey , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180778 , vital:43645 , xlink:href="https://doi.org/10.1016/j.forpol.2015.08.005"
- Description: Valuation of the contribution of non-timber forest products (NTFPs) to household incomes has been well researched in the rural and remote areas of the developing world. In comparison, there has been little investigation of the contribution of NTFPs in urban areas and amongst the urban poor. This paper reports results from a survey of 450 households across three towns on the use and value of tree NTFPs collected by households in the poorer areas from their own homesteads, open spaces within towns and at the urban periphery. Collection (and purchase) of tree NTFPs was widespread, especially of firewood and fruits. The ratio collected from homesteads relative to other urban spaces differed between products and the amount required. Overall, approximately 20% of household income was derived from urban tree NTFPs. The highest contribution (33%) was amongst the poorest sectors represented by mostly recent migrants to towns who were living in informal settlements whilst trying to establish a foothold in the urban economy. In the formal housing areas the contribution was at least 14%, which has been overlooked by standard income surveys in urban areas.
- Full Text:
- Date Issued: 2015
- Authors: Kaoma, Humphrey , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180778 , vital:43645 , xlink:href="https://doi.org/10.1016/j.forpol.2015.08.005"
- Description: Valuation of the contribution of non-timber forest products (NTFPs) to household incomes has been well researched in the rural and remote areas of the developing world. In comparison, there has been little investigation of the contribution of NTFPs in urban areas and amongst the urban poor. This paper reports results from a survey of 450 households across three towns on the use and value of tree NTFPs collected by households in the poorer areas from their own homesteads, open spaces within towns and at the urban periphery. Collection (and purchase) of tree NTFPs was widespread, especially of firewood and fruits. The ratio collected from homesteads relative to other urban spaces differed between products and the amount required. Overall, approximately 20% of household income was derived from urban tree NTFPs. The highest contribution (33%) was amongst the poorest sectors represented by mostly recent migrants to towns who were living in informal settlements whilst trying to establish a foothold in the urban economy. In the formal housing areas the contribution was at least 14%, which has been overlooked by standard income surveys in urban areas.
- Full Text:
- Date Issued: 2015
Visible light transformation of Rhodamine 6G using tetracarbazole zinc phthalocyanine when embedded in electrospun fibers and in the presence of ZnO and Ag particles
- Khoza, Phindile, Nyokong, Tebello
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189456 , vital:44848 , xlink:href="https://doi.org/10.1080/00958972.2015.1013944"
- Description: Herein, we report the photocatalytic transformation of Rhodamine 6G (Rh 6G) using tetracarbazole zinc phthalocyanine (TCbZnPc) when alone or when conjugated with ZnO macroparticles (ZnOMPs) and silver nanoparticles (AgNPs), represented as TCbZnPc–ZnOMPs and TCbZnPc–AgNPs, respectively. The photocatalysts were supported onto electrospun polystyrene fibers. The efficiency of TCbZnPc was improved by the presence of both ZnOMPs and AgNPs. HPLC equipped with UV–vis was used to study phototransformation products. The mechanism of transformation was via the N-de-ethylation of Rh 6G.
- Full Text:
- Date Issued: 2015
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189456 , vital:44848 , xlink:href="https://doi.org/10.1080/00958972.2015.1013944"
- Description: Herein, we report the photocatalytic transformation of Rhodamine 6G (Rh 6G) using tetracarbazole zinc phthalocyanine (TCbZnPc) when alone or when conjugated with ZnO macroparticles (ZnOMPs) and silver nanoparticles (AgNPs), represented as TCbZnPc–ZnOMPs and TCbZnPc–AgNPs, respectively. The photocatalysts were supported onto electrospun polystyrene fibers. The efficiency of TCbZnPc was improved by the presence of both ZnOMPs and AgNPs. HPLC equipped with UV–vis was used to study phototransformation products. The mechanism of transformation was via the N-de-ethylation of Rh 6G.
- Full Text:
- Date Issued: 2015
Photocatalytic behaviour of zinc tetraamino phthalocyanine-silver nanoparticles immobilized on chitosan beads
- Khoza, Phindile, Nyokong, Tebello
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189468 , vital:44849 , xlink:href="https://doi.org/10.1016/j.molcata.2015.01.017"
- Description: Photocatalytic degradation of Rhodamine 6G using unconjugated zinc tetraamino phthalocyanine (ZnTAPc) or when conjugated to Ag nanoparticles (ZnTAPc–AgNPs) is reported. Upon conjugating ZnTAPc to silver nanoparticles, the singlet oxygen production of the phthalocyanine was slightly increased. ZnTAPc and ZnTAPc–AgNPs were immobilized onto chitosan beads for ease of recovery after photocatalysis. Chitosan beads were characterized by FTIR, XRD and TGA. The photodegradation of Rhodamine 6G was used to evaluate the efficiency of the immobilized photocatalysts. In the presence of AgNPs, the photodegradation of Rhodamine 6G was enhanced. The apparent rates (k) were found to be 8.51 × 10−8 and 1.61 × 10−7 mol L−1 min−1 for chitosan supported ZnTAPc or ZnTAPc–AgNPs, respectively. The observation of good photocatalytic activity of the ZnTAPc when immobilized on chitosan proves the uncompromised efficiency of the photocatalysts even when confined in beads, showing great potential for the functionalized beads as heterogeneous catalysts.
- Full Text:
- Date Issued: 2015
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189468 , vital:44849 , xlink:href="https://doi.org/10.1016/j.molcata.2015.01.017"
- Description: Photocatalytic degradation of Rhodamine 6G using unconjugated zinc tetraamino phthalocyanine (ZnTAPc) or when conjugated to Ag nanoparticles (ZnTAPc–AgNPs) is reported. Upon conjugating ZnTAPc to silver nanoparticles, the singlet oxygen production of the phthalocyanine was slightly increased. ZnTAPc and ZnTAPc–AgNPs were immobilized onto chitosan beads for ease of recovery after photocatalysis. Chitosan beads were characterized by FTIR, XRD and TGA. The photodegradation of Rhodamine 6G was used to evaluate the efficiency of the immobilized photocatalysts. In the presence of AgNPs, the photodegradation of Rhodamine 6G was enhanced. The apparent rates (k) were found to be 8.51 × 10−8 and 1.61 × 10−7 mol L−1 min−1 for chitosan supported ZnTAPc or ZnTAPc–AgNPs, respectively. The observation of good photocatalytic activity of the ZnTAPc when immobilized on chitosan proves the uncompromised efficiency of the photocatalysts even when confined in beads, showing great potential for the functionalized beads as heterogeneous catalysts.
- Full Text:
- Date Issued: 2015
Modelling stock return volatility dynamics in selected African markets
- Authors: King, Daniel , Botha, Ferdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396104 , vital:69150 , xlink:href=" https://doi.org/10.1016/j.econmod.2014.11.008"
- Description: This paper examines whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002–2012. In the univariate portion of the paper, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. Accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important in capturing heteroscedasticity. However, those univariate models including a GARCH term perform comparatively poorly when used for forecasting purposes. In the multivariate study, the use of Markov-switching variance–covariance estimates improves risk-adjusted portfolio returns relative to portfolios constructed using the more conventional single-state models. While there is evidence that some Markov-switching models can provide better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture heteroscedasticity in the data remains problematic.
- Full Text:
- Date Issued: 2015
- Authors: King, Daniel , Botha, Ferdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396104 , vital:69150 , xlink:href=" https://doi.org/10.1016/j.econmod.2014.11.008"
- Description: This paper examines whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002–2012. In the univariate portion of the paper, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. Accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important in capturing heteroscedasticity. However, those univariate models including a GARCH term perform comparatively poorly when used for forecasting purposes. In the multivariate study, the use of Markov-switching variance–covariance estimates improves risk-adjusted portfolio returns relative to portfolios constructed using the more conventional single-state models. While there is evidence that some Markov-switching models can provide better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture heteroscedasticity in the data remains problematic.
- 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
The politics of interweaving performance cultures
- Authors: Krueger, Anton
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225719 , vital:49252 , xlink:href="https://doi.org/10.1080/10137548.2015.1014170"
- Description: According to the former president of the International Federation of Theatre Research (IFTR), Brian Singleton, the study of ‘[i]nterculturalism as a practice and a theory gained currency with Richard Schechner’s anthropologically-inspired new discipline of performance studies’ (p. 79). Schechner’s new discipline led to the formation of the annual Performance Studies International (PSI) conferences, and earlier this year I attended the twentieth instalment in Shanghai, which was held under the rubric of ‘Tradition and the Avant-Garde’. One of the things which struck me was the extent to which the (relatively) newly economically empowered Chinese theatre makers were creating grand productions based on Western theatre traditions. For example, many of the presentations for delegates were based on Western texts (such as Hamlet, Miss Julie and even a play by Woody Allen). And yet these productions were performed in Mandarin, using purist Chinese forms, such as Beijing Opera. During the discussions there seemed to be an awkward defensiveness from some of the Chinese hosts who insisted they were not ‘copying’ Western theatre, but that they were using it to express a pure Chinese aesthetic. There were also other performances at the conference, such as a series of parables called Confucius Disciples, which told didactic tales with content very foreign to a Western audience. A visiting troupe from Bulgaria presented their own version of some of these parables, using a strongly East European aesthetic to convey a Chinese message. In this way, experiments with cultural forms and content were clearly foregrounded by the conference presentations.
- Full Text:
- Date Issued: 2015
- Authors: Krueger, Anton
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225719 , vital:49252 , xlink:href="https://doi.org/10.1080/10137548.2015.1014170"
- Description: According to the former president of the International Federation of Theatre Research (IFTR), Brian Singleton, the study of ‘[i]nterculturalism as a practice and a theory gained currency with Richard Schechner’s anthropologically-inspired new discipline of performance studies’ (p. 79). Schechner’s new discipline led to the formation of the annual Performance Studies International (PSI) conferences, and earlier this year I attended the twentieth instalment in Shanghai, which was held under the rubric of ‘Tradition and the Avant-Garde’. One of the things which struck me was the extent to which the (relatively) newly economically empowered Chinese theatre makers were creating grand productions based on Western theatre traditions. For example, many of the presentations for delegates were based on Western texts (such as Hamlet, Miss Julie and even a play by Woody Allen). And yet these productions were performed in Mandarin, using purist Chinese forms, such as Beijing Opera. During the discussions there seemed to be an awkward defensiveness from some of the Chinese hosts who insisted they were not ‘copying’ Western theatre, but that they were using it to express a pure Chinese aesthetic. There were also other performances at the conference, such as a series of parables called Confucius Disciples, which told didactic tales with content very foreign to a Western audience. A visiting troupe from Bulgaria presented their own version of some of these parables, using a strongly East European aesthetic to convey a Chinese message. In this way, experiments with cultural forms and content were clearly foregrounded by the conference presentations.
- Full Text:
- Date Issued: 2015
Uncle Noodle
- Authors: Krueger, Anton
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229676 , vital:49699 , xlink:href="https://hdl.handle.net/10520/EJC176906"
- Description: “Ah,” he seemed surprised to see me, “Now you find out who really cares...” His kidneys hadn‟t been on the job in months, and with the machines failing, his hands were fattening into stubby yellow fingers, as the waste shored up inside of him. I touched his arm, and we joked about the broad blunt strokes of the casiotone the old dame played for the lunch-eaters next door. Uncle Noodle had always been my favourite. In a world where adults were always certain, ready to disdain and judge and pass verdict – I loved it that he was indecisive, insecure, unsure. Often wretched, often defeated. His heart had chasmed in the wake of his wife‟s leaving, finally dividing him from all his hopes, collapsing his dignity destroying his happiness machinery.
- Full Text:
- Date Issued: 2015
- Authors: Krueger, Anton
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229676 , vital:49699 , xlink:href="https://hdl.handle.net/10520/EJC176906"
- Description: “Ah,” he seemed surprised to see me, “Now you find out who really cares...” His kidneys hadn‟t been on the job in months, and with the machines failing, his hands were fattening into stubby yellow fingers, as the waste shored up inside of him. I touched his arm, and we joked about the broad blunt strokes of the casiotone the old dame played for the lunch-eaters next door. Uncle Noodle had always been my favourite. In a world where adults were always certain, ready to disdain and judge and pass verdict – I loved it that he was indecisive, insecure, unsure. Often wretched, often defeated. His heart had chasmed in the wake of his wife‟s leaving, finally dividing him from all his hopes, collapsing his dignity destroying his happiness machinery.
- Full Text:
- Date Issued: 2015
Whose voice is it anyway?
- Authors: Krueger, Anton
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225695 , vital:49249 , xlink:href="https://doi.org/10.1080/1013929X.2015.1086195"
- Description: This essay surveys a number of different interpretations of the metaphor of “voice”. It begins by exploring the use of free writing exercises as a means of nurturing the emergence of physical (audible) voice in creative writing classes before assessing some of the ramifications and implications of the trope, both diachronically and synchronically. A key issue of this discussion is whether voice is regarded as individual or social.
- Full Text:
- Date Issued: 2015
- Authors: Krueger, Anton
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225695 , vital:49249 , xlink:href="https://doi.org/10.1080/1013929X.2015.1086195"
- Description: This essay surveys a number of different interpretations of the metaphor of “voice”. It begins by exploring the use of free writing exercises as a means of nurturing the emergence of physical (audible) voice in creative writing classes before assessing some of the ramifications and implications of the trope, both diachronically and synchronically. A key issue of this discussion is whether voice is regarded as individual or social.
- Full Text:
- Date Issued: 2015
“Ha! Relationships? I only shout at them!”: Strategic management of discordant rapport in an African small business context
- Lauriks, Sanne, Siebörger, Ian, de Vos, Mark
- Authors: Lauriks, Sanne , Siebörger, Ian , de Vos, Mark
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385338 , vital:68009 , xlink:href="https://doi.org/10.1515/pr-2015-0002"
- Description: This study demonstrates how and why interactants at a tyre fitment centre in Grahamstown, South Africa, manage discordant interpersonal relationships in strategic ways. Individuals in a post-apartheid small business respond to their social and economic context and exercise agency to their advantage in doing so. This study draws on linguistic ethnography (Rampton 2007) and the Rapport Management Framework (RMF, Spencer-Oatey 2000b, 2011), itself a development of politeness theory (Brown and Levinson 1987). An initial RMF analysis ran into difficulties around interactions that at first glance appeared to be oriented toward Rapport Challenge and Neglect. Upon closer examination, it appeared that discordant rapport was being actively maintained in this business. This led us to address underdeveloped areas of RMF that were not responsive enough to describe naturally occurring small business interactions, and propose an Enhanced Rapport Management Framework to overcome its inadequacies. We conclude that people may deliberately maintain discordant relationships when it is in their best interests to do so. Thus, contrary to a common-sense belief that harmonious social relations are an intrinsic good, we found that promoting discordant social relations can be understood as a rational response to individuals’ social and economic contexts, particularly in conditions such as those in many postcolonial African societies.
- Full Text:
- Date Issued: 2015
- Authors: Lauriks, Sanne , Siebörger, Ian , de Vos, Mark
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385338 , vital:68009 , xlink:href="https://doi.org/10.1515/pr-2015-0002"
- Description: This study demonstrates how and why interactants at a tyre fitment centre in Grahamstown, South Africa, manage discordant interpersonal relationships in strategic ways. Individuals in a post-apartheid small business respond to their social and economic context and exercise agency to their advantage in doing so. This study draws on linguistic ethnography (Rampton 2007) and the Rapport Management Framework (RMF, Spencer-Oatey 2000b, 2011), itself a development of politeness theory (Brown and Levinson 1987). An initial RMF analysis ran into difficulties around interactions that at first glance appeared to be oriented toward Rapport Challenge and Neglect. Upon closer examination, it appeared that discordant rapport was being actively maintained in this business. This led us to address underdeveloped areas of RMF that were not responsive enough to describe naturally occurring small business interactions, and propose an Enhanced Rapport Management Framework to overcome its inadequacies. We conclude that people may deliberately maintain discordant relationships when it is in their best interests to do so. Thus, contrary to a common-sense belief that harmonious social relations are an intrinsic good, we found that promoting discordant social relations can be understood as a rational response to individuals’ social and economic contexts, particularly in conditions such as those in many postcolonial African societies.
- Full Text:
- Date Issued: 2015
Surface modification of silica-coated gadolinium oxide nanoparticles with zinc tetracarboxyphenoxy phthalocyanine for the photodegradation of Orange G
- Ledwaba, Mpho, Masilela, Nkosiphile, Nyokong, Tebello, Antunes, Edith M
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193621 , vital:45353 , xlink:href="https://doi.org/10.1016/j.molcata.2015.03.023"
- Description: Zinc tetracarboxyphenoxy phthalocyanine was covalently linked to Gd2O3 nanoparticles for the photocatalytic degradation of Orange G. Characterization of the composite was carried out using XRD, TEM, XPS, UV–vis spectroscopy and FT-IR spectroscopy. The composite showed improved photophysical properties over the phthalocyanine alone and the catalyst was found to be reusable. Analyses of the photodegradation rates of the azo dye indicated pseudo first-order kinetics.
- Full Text:
- Date Issued: 2015
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193621 , vital:45353 , xlink:href="https://doi.org/10.1016/j.molcata.2015.03.023"
- Description: Zinc tetracarboxyphenoxy phthalocyanine was covalently linked to Gd2O3 nanoparticles for the photocatalytic degradation of Orange G. Characterization of the composite was carried out using XRD, TEM, XPS, UV–vis spectroscopy and FT-IR spectroscopy. The composite showed improved photophysical properties over the phthalocyanine alone and the catalyst was found to be reusable. Analyses of the photodegradation rates of the azo dye indicated pseudo first-order kinetics.
- Full Text:
- Date Issued: 2015
Facile synthesis, spectroscopic and electrochemical properties, and theoretical calculations of porphyrin dimers with a bridging amide-bonded xanthene moiety
- Liang, Xu, Xu, Li, Li, Minzhi, Mack, John, Stone, Justin, Nyokong, Tebello, Jiang, Yu, Kobayashi, Nagao, Zhu, Weihua
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241390 , vital:50935 , xlink:href="https://doi.org/10.1142/S1088424615500492"
- Description: A free base porphyrin dimer bridged by a flexible amide-bonded xanthene moiety and its binuclear zinc(II) complex zinc(II) complex were synthesized and characterized. Structural characterization by MS and 1H NMR spectroscopy confirmed the bridged porphyrin dimer structure. The properties of the dimers were characterized by IR, UV-visible absorption, fluorescence and magnetic circular dichroism (MCD) spectroscopy, and electrochemistry studies. Theoretical calculations were carried out to analyze the electronic structures of porphyrin dimers with a bridging amide-bonded xanthene moiety.
- Full Text:
- Date Issued: 2015
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241390 , vital:50935 , xlink:href="https://doi.org/10.1142/S1088424615500492"
- Description: A free base porphyrin dimer bridged by a flexible amide-bonded xanthene moiety and its binuclear zinc(II) complex zinc(II) complex were synthesized and characterized. Structural characterization by MS and 1H NMR spectroscopy confirmed the bridged porphyrin dimer structure. The properties of the dimers were characterized by IR, UV-visible absorption, fluorescence and magnetic circular dichroism (MCD) spectroscopy, and electrochemistry studies. Theoretical calculations were carried out to analyze the electronic structures of porphyrin dimers with a bridging amide-bonded xanthene moiety.
- Full Text:
- Date Issued: 2015