“Turn on” fluorescence enhancement of Zn octacarboxyphthaloyanine-graphene oxide conjugates by hydrogen peroxide
- Shumba, Munyaradzi, Mashazi, Philani N, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190438 , vital:44994 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyaninereduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190438 , vital:44994 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyaninereduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
Collaborative learning of water conservation practices: cultivation and expansion of a learning network around rainwater harvesting demonstration sites in the Eastern Cape, South Africa
- Pesanayi, Tichaona V, Weaver, Kim N
- Authors: Pesanayi, Tichaona V , Weaver, Kim N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392086 , vital:68720 , xlink:href="https://www.ajol.info/index.php/sajae/article/view/138570"
- Description: Learning together in mediated voluntary networks can mobilise skills and innovations that help to facilitate learning and uptake of rainwater harvesting and conservation practices. It boosts extension capacity while at the same time growing farmer capabilities, tapping on the distributed cognition. These practices help to heal wicked problems of drought and global change challenges affecting marginalised farmers in South Africa. South Africa has water, nutrition and food security challenges, especially the Eastern Cape Province where there is a relatively high level of poverty. These challenges place heavy pressure on the agricultural sector as it is the main user of the allocated water in the country. In this paper, the learning of and agency for rainwater harvesting and conservation practices are explored as responses to these challenges. Despite existing cultural histories of such practices among the amaXhosa people, information on these practices is not readily available to small-scale rural farmers who thus struggle for the want of knowing. This research forms part of a Water Research Commission project, Amanzi for Food, whose intention is to mediate collaborative and co-engaged learning among networked farmers, extension workers, researchers and agricultural educators through course-mediated use of Water Research Commission rainwater harvesting and conservation materials.
- Full Text:
- Date Issued: 2016
- Authors: Pesanayi, Tichaona V , Weaver, Kim N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392086 , vital:68720 , xlink:href="https://www.ajol.info/index.php/sajae/article/view/138570"
- Description: Learning together in mediated voluntary networks can mobilise skills and innovations that help to facilitate learning and uptake of rainwater harvesting and conservation practices. It boosts extension capacity while at the same time growing farmer capabilities, tapping on the distributed cognition. These practices help to heal wicked problems of drought and global change challenges affecting marginalised farmers in South Africa. South Africa has water, nutrition and food security challenges, especially the Eastern Cape Province where there is a relatively high level of poverty. These challenges place heavy pressure on the agricultural sector as it is the main user of the allocated water in the country. In this paper, the learning of and agency for rainwater harvesting and conservation practices are explored as responses to these challenges. Despite existing cultural histories of such practices among the amaXhosa people, information on these practices is not readily available to small-scale rural farmers who thus struggle for the want of knowing. This research forms part of a Water Research Commission project, Amanzi for Food, whose intention is to mediate collaborative and co-engaged learning among networked farmers, extension workers, researchers and agricultural educators through course-mediated use of Water Research Commission rainwater harvesting and conservation materials.
- Full Text:
- Date Issued: 2016
Food waste generation and potential interventions at Rhodes University, South Africa
- Painter, Kathleen, Thondhlana, Gladman, Kua, Harn W
- Authors: Painter, Kathleen , Thondhlana, Gladman , Kua, Harn W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67733 , vital:29135 , https://doi.org/10.1016/j.wasman.2016.07.013
- Description: Publisher version , Estimation of food waste generation represents the first step when considering efforts to reduce waste generation and monitor food waste reduction against set targets. This study reports on an estimation of food waste generated in university dining halls at Rhodes University, South Africa. Daily food waste generation was estimated at about 555 g per student or 2 tonnes across all sample dining halls, translating to about 450 tonnes per year. The results show that food waste is influenced by an array of contextual factors, including distance to dining hall, gender composition of hall and meal times and meal options. It is estimated that the university could save up to US$ 80 000 annually for every 10% reduction in the current rate of food waste generation. Possible educational, technical and administrative interventions for food waste reduction are discussed.
- Full Text: false
- Date Issued: 2016
- Authors: Painter, Kathleen , Thondhlana, Gladman , Kua, Harn W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67733 , vital:29135 , https://doi.org/10.1016/j.wasman.2016.07.013
- Description: Publisher version , Estimation of food waste generation represents the first step when considering efforts to reduce waste generation and monitor food waste reduction against set targets. This study reports on an estimation of food waste generated in university dining halls at Rhodes University, South Africa. Daily food waste generation was estimated at about 555 g per student or 2 tonnes across all sample dining halls, translating to about 450 tonnes per year. The results show that food waste is influenced by an array of contextual factors, including distance to dining hall, gender composition of hall and meal times and meal options. It is estimated that the university could save up to US$ 80 000 annually for every 10% reduction in the current rate of food waste generation. Possible educational, technical and administrative interventions for food waste reduction are discussed.
- Full Text: false
- Date Issued: 2016
Nonlinear optical response of a low symmetry phthalocyanine in the presence of gold nanoparticles when in solution or embedded in poly acrylic acid polymer thin films
- Bankole, Owolabi M, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188719 , vital:44779 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.12.014"
- Description: In this article, we explored the photophysical and nonlinear optical (NLO) characterizations of low symmetry phthalocyanine (ZnPc-NH2) covalently linked to MPA-capped AuNPs (ZnPc-NH2-AuNPs) and poly acrylic acid (ZnPc-NH2-PAA). Nonlinear optical (NLO) properties of the samples were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. We observed enhanced photophysical and nonlinear optical behaviour for the ZnPc-NH2 in presence of AuNPs. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, ZnPc-NH2-AuNPs was found to exhibit improved nonlinear optical response compared to the ZnPc-NH2 and ZnPc-NH2-PAA. Both ZnPc-NH2-AuNPs and ZnPc-NH2 doped in PAA possess strong nonlinear absorption coefficients and very low limiting thresholds than when measured in solution.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188719 , vital:44779 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.12.014"
- Description: In this article, we explored the photophysical and nonlinear optical (NLO) characterizations of low symmetry phthalocyanine (ZnPc-NH2) covalently linked to MPA-capped AuNPs (ZnPc-NH2-AuNPs) and poly acrylic acid (ZnPc-NH2-PAA). Nonlinear optical (NLO) properties of the samples were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. We observed enhanced photophysical and nonlinear optical behaviour for the ZnPc-NH2 in presence of AuNPs. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, ZnPc-NH2-AuNPs was found to exhibit improved nonlinear optical response compared to the ZnPc-NH2 and ZnPc-NH2-PAA. Both ZnPc-NH2-AuNPs and ZnPc-NH2 doped in PAA possess strong nonlinear absorption coefficients and very low limiting thresholds than when measured in solution.
- Full Text:
- Date Issued: 2016
Synthesis and optical limiting properties of new lanthanide bis-and tris-phthalocyanines
- Sekhosana, Kutloana Edward, Manyeruke, Meloddy Hlatini, Nyokong, Tebello
- Authors: Sekhosana, Kutloana Edward , Manyeruke, Meloddy Hlatini , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240063 , vital:50795 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.05.068"
- Description: This manuscript reports on syntheses of new multi-decker phthalocyanines, namely: bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} cerium(III) (2), tris-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} dicerium(III) (4) and bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} gadolinium(III) (5). Complex 4 which is a tris phthalocyanine showed better nonlinear optical behavior in solution than 2 which is a bis phthalocyanine, both containing the same central metal, Ce. All the three molecules possess good optical limiting properties judged by the limiting threshold values which ranged from 0.04 to 0.09 J cm−2 with complex 5 embedded in thin films, showing the lowest value of 0.04 J cm−2. Furthermore, nonlinear optical processes responsible for reverse saturable absorption data are investigated.
- Full Text:
- Date Issued: 2016
- Authors: Sekhosana, Kutloana Edward , Manyeruke, Meloddy Hlatini , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240063 , vital:50795 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.05.068"
- Description: This manuscript reports on syntheses of new multi-decker phthalocyanines, namely: bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} cerium(III) (2), tris-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} dicerium(III) (4) and bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} gadolinium(III) (5). Complex 4 which is a tris phthalocyanine showed better nonlinear optical behavior in solution than 2 which is a bis phthalocyanine, both containing the same central metal, Ce. All the three molecules possess good optical limiting properties judged by the limiting threshold values which ranged from 0.04 to 0.09 J cm−2 with complex 5 embedded in thin films, showing the lowest value of 0.04 J cm−2. Furthermore, nonlinear optical processes responsible for reverse saturable absorption data are investigated.
- Full Text:
- Date Issued: 2016
Natural resource use, incomes, and poverty along the rural–urban continuum of two medium-sized, South African towns
- Ward, Catherine D, Shackleton, Charlie M
- Authors: Ward, Catherine D , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180790 , vital:43646 , xlink:href="https://doi.org/10.1016/j.worlddev.2015.10.025"
- Description: Urbanization is a significant driver of global change, reshaping livelihoods, productive activities, and incomes. Yet, many elements of what are typically regarded as rural activities can be found in urban places and vice versa. We report on the incomes from land- and cash-based activities along the rural–urban gradient of two South African towns. Although the dominant income strategies varied, all households had more than one income source. Use of wild resources and agriculture were common in urban settings, although variable between and within towns. Poverty levels would be 5–10% higher in the absence of natural resource-based incomes.
- Full Text:
- Date Issued: 2016
- Authors: Ward, Catherine D , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180790 , vital:43646 , xlink:href="https://doi.org/10.1016/j.worlddev.2015.10.025"
- Description: Urbanization is a significant driver of global change, reshaping livelihoods, productive activities, and incomes. Yet, many elements of what are typically regarded as rural activities can be found in urban places and vice versa. We report on the incomes from land- and cash-based activities along the rural–urban gradient of two South African towns. Although the dominant income strategies varied, all households had more than one income source. Use of wild resources and agriculture were common in urban settings, although variable between and within towns. Poverty levels would be 5–10% higher in the absence of natural resource-based incomes.
- Full Text:
- Date Issued: 2016
Conjugation of azide-functionalised CdSe/ZnS quantum dots with tetrakis (5-hexyn-oxy) Fe (II) phthalocyanine via click chemistry for electrocatalysis
- Nxele, Siphesihle R, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188755 , vital:44782 , xlink:href="https://doi.org/10.1016/j.electacta.2016.01.234"
- Description: In this work, azide-funtionalised CdSe/ZnS QDs are conjugated with tetrakis(5-hexyn-oxy) Fe(II) phthalocyanine for the electrocatalytic detection of paraquat. The conjugate was fully characterised using various techniques to confirm the success of the reaction. They also showed good electrocatalytic ability towards the electroreduction of paraquat with limits of detection (LoD) of 5.9 × 10−9 μM which is a great improvement compared to other reported sensors for this analyte.
- Full Text:
- Date Issued: 2016
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188755 , vital:44782 , xlink:href="https://doi.org/10.1016/j.electacta.2016.01.234"
- Description: In this work, azide-funtionalised CdSe/ZnS QDs are conjugated with tetrakis(5-hexyn-oxy) Fe(II) phthalocyanine for the electrocatalytic detection of paraquat. The conjugate was fully characterised using various techniques to confirm the success of the reaction. They also showed good electrocatalytic ability towards the electroreduction of paraquat with limits of detection (LoD) of 5.9 × 10−9 μM which is a great improvement compared to other reported sensors for this analyte.
- Full Text:
- Date Issued: 2016
Can local use assist in controlling invasive alien species in tropical forests?: The case of Lantana camara in southern India
- Kannan, Ramesh, Shackleton, Charlie M, Krishnan, Smitha, Shaanker, Ramanan U
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Krishnan, Smitha , Shaanker, Ramanan U
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180423 , vital:43387 , xlink:href="https://doi.org/10.1016/j.foreco.2016.06.016"
- Description: Many invasive alien species (IAS) are used by local communities for a variety of subsistence and income generating purposes. This frequently poses a conflict of interest for their removal due to forest conservation and biodiversity concerns. However, if local use can simultaneously check or control specific IAS, the conflict can be avoided and both development and forest conservation perspectives accommodated in the short to medium term. We examine this for Lantana camara invasion in southern India through assessment of the demand for and impacts of harvesting on this globally problematic IAS. We interviewed local artisans regarding their knowledge and quantities of Lantana used, along with forest surveys to estimate Lantana densities and size classes in harvested and unharvested sites, and lastly we undertook controlled cutting in moist and dry deciduous forests in both the wet and dry seasons to examine rate of regrowth and mortality. Over the entire study area the abundance of Lantana far outweighed local demand, but at small scales around villages, density and size classes were significantly reduced through harvesting. The controlled cutting experiment showed marked seasonal differences, with the most severe cutting intensity resulting in significant mortality when Lantana plants were cut in the wet season, but with limited effect when cut in the dry season. We conclude that promoting local use of IAS may be a feasible approach in controlling them and thereby limiting their impacts in forests.
- Full Text:
- Date Issued: 2016
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Krishnan, Smitha , Shaanker, Ramanan U
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180423 , vital:43387 , xlink:href="https://doi.org/10.1016/j.foreco.2016.06.016"
- Description: Many invasive alien species (IAS) are used by local communities for a variety of subsistence and income generating purposes. This frequently poses a conflict of interest for their removal due to forest conservation and biodiversity concerns. However, if local use can simultaneously check or control specific IAS, the conflict can be avoided and both development and forest conservation perspectives accommodated in the short to medium term. We examine this for Lantana camara invasion in southern India through assessment of the demand for and impacts of harvesting on this globally problematic IAS. We interviewed local artisans regarding their knowledge and quantities of Lantana used, along with forest surveys to estimate Lantana densities and size classes in harvested and unharvested sites, and lastly we undertook controlled cutting in moist and dry deciduous forests in both the wet and dry seasons to examine rate of regrowth and mortality. Over the entire study area the abundance of Lantana far outweighed local demand, but at small scales around villages, density and size classes were significantly reduced through harvesting. The controlled cutting experiment showed marked seasonal differences, with the most severe cutting intensity resulting in significant mortality when Lantana plants were cut in the wet season, but with limited effect when cut in the dry season. We conclude that promoting local use of IAS may be a feasible approach in controlling them and thereby limiting their impacts in forests.
- Full Text:
- Date Issued: 2016
Electrode modification using nanocomposites of boron or nitrogen doped graphene oxide and cobalt (II) tetra aminophenoxy phthalocyanine nanoparticles
- Shumba, Munyaradzi, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188699 , vital:44777 , xlink:href="https://doi.org/10.1016/j.electacta.2016.02.166"
- Description: Reduced graphene oxide nanosheets (rGONS), reduced boron doped graphene oxide nanosheets (rBDGONS) and reduced nitrogen doped graphene oxide nanosheets (rNDGONS) and their composites with cobalt tetra aminophenoxy phthalocyanine nanoparticles (CoTAPhPcNP) were employed towards the detection of hydrogen peroxide. The nanomaterials were characterized by absorption spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, linear sweep voltammetry and cyclic voltammetry. rNDGONS showed excellent electrooxidation and electroreduction of hydrogen peroxide supported by superior surface coverage values. The inclusion of nanosized Pc significantly lowered the reduction overpotential. CoTAPhPcNP-rNDGONS-GCE gave a sensitivity of 39.30 mA/M, catalytic rate constant of 1 × 103 M−1 s−1 and a detection limit of 8.2 nM. An adsorption equilibrium constant and Gibbs free energy of 1.26 × 103 M−1 and −17.69 kJ mol−1 respectively were observed.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzi , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188699 , vital:44777 , xlink:href="https://doi.org/10.1016/j.electacta.2016.02.166"
- Description: Reduced graphene oxide nanosheets (rGONS), reduced boron doped graphene oxide nanosheets (rBDGONS) and reduced nitrogen doped graphene oxide nanosheets (rNDGONS) and their composites with cobalt tetra aminophenoxy phthalocyanine nanoparticles (CoTAPhPcNP) were employed towards the detection of hydrogen peroxide. The nanomaterials were characterized by absorption spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, linear sweep voltammetry and cyclic voltammetry. rNDGONS showed excellent electrooxidation and electroreduction of hydrogen peroxide supported by superior surface coverage values. The inclusion of nanosized Pc significantly lowered the reduction overpotential. CoTAPhPcNP-rNDGONS-GCE gave a sensitivity of 39.30 mA/M, catalytic rate constant of 1 × 103 M−1 s−1 and a detection limit of 8.2 nM. An adsorption equilibrium constant and Gibbs free energy of 1.26 × 103 M−1 and −17.69 kJ mol−1 respectively were observed.
- Full Text:
- Date Issued: 2016
The optical limiting of blue and green ytterbium double-decker phthalocyanines in solution and in poly (acrylic acid) as thin films
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188585 , vital:44767 , xlink:href="https://doi.org/10.1016/j.ica.2016.05.026"
- Description: Bis{1(4), 8(11), 15(18), 22(25)-tetra(4-tert-butylphenoxy)phthalocyaninato} ytterbium(III) (2a) (the green form) was synthesized and reduced to form 2b (the blue form). Nonlinear optical parameters for complex 2 in green and blue forms were determined using the Z-scan technique and the values of third-order imaginary susceptibility (Im[χ(3)]) and second-order hyperpolarizability (γ) of the order of 10−9 (for 2b) and 10−27 esu, respectively, were obtained in solution. In poly(acrylic acid) as a thin film, complex 2a showed extremely high Im[χ(3)] and γ values of the order 10−8 and 10−25 respectively. A low optical limiting threshold value of 0.075 J cm−2 was obtained for the thin film 2a.
- Full Text:
- Date Issued: 2016
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188585 , vital:44767 , xlink:href="https://doi.org/10.1016/j.ica.2016.05.026"
- Description: Bis{1(4), 8(11), 15(18), 22(25)-tetra(4-tert-butylphenoxy)phthalocyaninato} ytterbium(III) (2a) (the green form) was synthesized and reduced to form 2b (the blue form). Nonlinear optical parameters for complex 2 in green and blue forms were determined using the Z-scan technique and the values of third-order imaginary susceptibility (Im[χ(3)]) and second-order hyperpolarizability (γ) of the order of 10−9 (for 2b) and 10−27 esu, respectively, were obtained in solution. In poly(acrylic acid) as a thin film, complex 2a showed extremely high Im[χ(3)] and γ values of the order 10−8 and 10−25 respectively. A low optical limiting threshold value of 0.075 J cm−2 was obtained for the thin film 2a.
- Full Text:
- Date Issued: 2016
Development of nanocomposites of phosphorus-nitrogen co-doped graphene oxide nanosheets and nanosized cobalt phthalocyanines for electrocatalysis
- Shumba, Munyaradzai, Nyokong, Tebello
- Authors: Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188574 , vital:44766 , xlink:href="https://doi.org/10.1016/j.electacta.2016.07.079"
- Description: Conjugates of reduced phosphorus-nitrogen co-doped graphene oxide nanosheets (rPNDGONS), reduced phosphorus doped graphene oxide nanosheets (rPDGONS), reduced nitrogen doped graphene oxide nanosheets (rNDGONS), reduced pyrolised graphene oxide nanosheets (rpyGONS) with nanosized cobalt (II) phthalocyanine (CoPcNP) or cobalt tetra amino phenoxy phthalocyanine (CoTAPhPcNP) were characterised and tested for their electrocatalytic behaviour towards the detection of hydrogen peroxide. Cyclic and linear scan voltammetries, and chronoamperometry were used to evaluate the electrocatalytic nature of the designed probes. For hydrogen peroxide detection, CoPcNP-rPNDGONS-GCE oxidation gave sensitivity of 12.00 mA/M, limit of detection of 4.48 nM, a rate constant of 2.66 × 105 M−1 s−1, adsorption equilibrium constant of 3.7 × 102 M−1 and Gibbs free energy −14.84 kJmol−1. The lowest detection limit was obtained for CoTAPhPcNP-rPNDGONS-GCE at 1.21 nM.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188574 , vital:44766 , xlink:href="https://doi.org/10.1016/j.electacta.2016.07.079"
- Description: Conjugates of reduced phosphorus-nitrogen co-doped graphene oxide nanosheets (rPNDGONS), reduced phosphorus doped graphene oxide nanosheets (rPDGONS), reduced nitrogen doped graphene oxide nanosheets (rNDGONS), reduced pyrolised graphene oxide nanosheets (rpyGONS) with nanosized cobalt (II) phthalocyanine (CoPcNP) or cobalt tetra amino phenoxy phthalocyanine (CoTAPhPcNP) were characterised and tested for their electrocatalytic behaviour towards the detection of hydrogen peroxide. Cyclic and linear scan voltammetries, and chronoamperometry were used to evaluate the electrocatalytic nature of the designed probes. For hydrogen peroxide detection, CoPcNP-rPNDGONS-GCE oxidation gave sensitivity of 12.00 mA/M, limit of detection of 4.48 nM, a rate constant of 2.66 × 105 M−1 s−1, adsorption equilibrium constant of 3.7 × 102 M−1 and Gibbs free energy −14.84 kJmol−1. The lowest detection limit was obtained for CoTAPhPcNP-rPNDGONS-GCE at 1.21 nM.
- Full Text:
- Date Issued: 2016
The interaction between graphene quantum dots grafted with polyethyleneimine and Au@ Ag nanoparticles
- Achadu, Ojodomo John, Uddin, Imran, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188679 , vital:44775 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.03.016"
- Description: Graphene quantum dots grafted with polyethyleneimine (GQDs-PEI) and Au@Ag core-shell nanoparticles blend was demonstrated to be a novel biosensing nanoprobe for the rapid and highly sensitive detection of biothiols such as cysteine (Cys), homocysteine (Hcys) and glutathione (GSH). The fluorescence emission of GQDs-PEI was quenched efficiently upon interaction with Au@Ag core-shell nanoparticles. The quenched fluorescence emission of the GQDs-PEI was restored in the presence of the biothiols. The fluorimetric sensing is based on the strong affinity between the mercapto (SH) groups of the biothiols and the Au@Ag core-shell nanoparticles by which the interaction between GQDs-PEI and Au@Ag core-shell nanoparticles was disrupted with a consequent modulation (‘turn-on’) of the quenched GQDs-PEI emission. Thus, a new, simple, rapid and highly sensitive fluorescence nanoprobe for detecting biothiols has been developed in this work.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188679 , vital:44775 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.03.016"
- Description: Graphene quantum dots grafted with polyethyleneimine (GQDs-PEI) and Au@Ag core-shell nanoparticles blend was demonstrated to be a novel biosensing nanoprobe for the rapid and highly sensitive detection of biothiols such as cysteine (Cys), homocysteine (Hcys) and glutathione (GSH). The fluorescence emission of GQDs-PEI was quenched efficiently upon interaction with Au@Ag core-shell nanoparticles. The quenched fluorescence emission of the GQDs-PEI was restored in the presence of the biothiols. The fluorimetric sensing is based on the strong affinity between the mercapto (SH) groups of the biothiols and the Au@Ag core-shell nanoparticles by which the interaction between GQDs-PEI and Au@Ag core-shell nanoparticles was disrupted with a consequent modulation (‘turn-on’) of the quenched GQDs-PEI emission. Thus, a new, simple, rapid and highly sensitive fluorescence nanoprobe for detecting biothiols has been developed in this work.
- Full Text:
- Date Issued: 2016
Nonlinear optical behavior of alkyne terminated phthalocyanines in solution and when embedded in polysulfone as thin films: effects of aggregation
- Bankole, Owolabi M, Yilmaz, Yusuf, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Yilmaz, Yusuf , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189110 , vital:44817 , xlink:href="https://doi.org/10.1016/j.optmat.2015.11.041"
- Description: We report here for the first time, on the comparative studies of the photophysical and optical limiting behavior of our two novel phthalocyanines namely 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyanines 2, and 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyaninato zinc (II) (3) in solution and thin films. Nonlinear optical (NLO) properties of the samples in solution and contained in polysulfone (PSU) thin films were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. Effects of aggregation and disaggregation on the NLO performance of metal-free phthalocyanine are reported in detail. Our findings showed that the prepared Pcs show larger nonlinear absorption coefficient and lower limiting thresholds when embedded in polysulfone films compared to in solutions. The values of nonlinear susceptibility and hyperpolarizability recorded for 3-PSU in this work are respectively, ∼2.09 × 10−8 esu and ∼1.02 × 10−26 esu. These values are among the largest values reported for phthalocyanines and other macrocycles doped on polymer matrices.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Yilmaz, Yusuf , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189110 , vital:44817 , xlink:href="https://doi.org/10.1016/j.optmat.2015.11.041"
- Description: We report here for the first time, on the comparative studies of the photophysical and optical limiting behavior of our two novel phthalocyanines namely 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyanines 2, and 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyaninato zinc (II) (3) in solution and thin films. Nonlinear optical (NLO) properties of the samples in solution and contained in polysulfone (PSU) thin films were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. Effects of aggregation and disaggregation on the NLO performance of metal-free phthalocyanine are reported in detail. Our findings showed that the prepared Pcs show larger nonlinear absorption coefficient and lower limiting thresholds when embedded in polysulfone films compared to in solutions. The values of nonlinear susceptibility and hyperpolarizability recorded for 3-PSU in this work are respectively, ∼2.09 × 10−8 esu and ∼1.02 × 10−26 esu. These values are among the largest values reported for phthalocyanines and other macrocycles doped on polymer matrices.
- Full Text:
- Date Issued: 2016
Fluorescence behavior of nanoconjugates of graphene quantum dots and zinc phthalocyanines
- Achadu, Ojodomo John, Uddin, Imran, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188777 , vital:44784 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.11.006"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanines interactions in different modes (covalent and non-covalent) are reported in this study. GQDs were covalently attached to the following complexes: zinc tetraamino phthalocyanine (ZnTAPc) via amide coupling, zinc tetracarboxyphenoxy Pc (ZnTCPPc) (π–π interaction) and cationic zinc tetrapyridiloxy Pc (ZnTmPyPc) (ionic interaction). GQDs fluorescence was quenched in the presence of the ZnPc derivatives. The nanoensembles of GQDs–ZnPcs showed stimulated emissions of the ZnPcs. The suggested quenching mechanism is through Förster resonance energy transfer (FRET). These novel nanoensembles hold promise for various optical and luminescence based applications.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188777 , vital:44784 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.11.006"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanines interactions in different modes (covalent and non-covalent) are reported in this study. GQDs were covalently attached to the following complexes: zinc tetraamino phthalocyanine (ZnTAPc) via amide coupling, zinc tetracarboxyphenoxy Pc (ZnTCPPc) (π–π interaction) and cationic zinc tetrapyridiloxy Pc (ZnTmPyPc) (ionic interaction). GQDs fluorescence was quenched in the presence of the ZnPc derivatives. The nanoensembles of GQDs–ZnPcs showed stimulated emissions of the ZnPcs. The suggested quenching mechanism is through Förster resonance energy transfer (FRET). These novel nanoensembles hold promise for various optical and luminescence based applications.
- Full Text:
- Date Issued: 2016
Encouraging pro-environmental behaviour: energy use and recycling at Rhodes University, South Africa
- Mtutu, Paidamoyo, Thondhlana, Gladman
- Authors: Mtutu, Paidamoyo , Thondhlana, Gladman
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67743 , vital:29136 , https://doi.org/10.1016/j.habitatint.2015.11.031
- Description: Publisher version , The rapid expansion of student numbers, staff and support infrastructures in higher education institutions often result in increased demand for resources such as energy and paper. Promoting pro-environmental behaviour is critical if higher education institutions are to achieve sustainable resource use. Using surveys, reported energy use and recycling behaviour of staff and students in the Faculty of Education at Rhodes University, South Africa was explored. The results showed that self-reported pro-environmental behaviour was mediated by demographic factors and personal values such as ‘liking of aesthetic beauty and biodiversity’, ‘social relations’, ‘a varied life’ and ‘freedom’. Personal values, though key in shaping participants' attitudes toward the environment did not always translate into pro-environmental behaviour. Situational factors beyond the control of participants were cited as barriers to pro-environmental actions. Lessons from this study point to the need to carefully study the assumptions underlying intervention strategies aimed at promoting pro-environmental behaviour and to get rid of barriers to enable pro-environmental actions.
- Full Text: false
- Date Issued: 2016
Encouraging pro-environmental behaviour: energy use and recycling at Rhodes University, South Africa
- Authors: Mtutu, Paidamoyo , Thondhlana, Gladman
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67743 , vital:29136 , https://doi.org/10.1016/j.habitatint.2015.11.031
- Description: Publisher version , The rapid expansion of student numbers, staff and support infrastructures in higher education institutions often result in increased demand for resources such as energy and paper. Promoting pro-environmental behaviour is critical if higher education institutions are to achieve sustainable resource use. Using surveys, reported energy use and recycling behaviour of staff and students in the Faculty of Education at Rhodes University, South Africa was explored. The results showed that self-reported pro-environmental behaviour was mediated by demographic factors and personal values such as ‘liking of aesthetic beauty and biodiversity’, ‘social relations’, ‘a varied life’ and ‘freedom’. Personal values, though key in shaping participants' attitudes toward the environment did not always translate into pro-environmental behaviour. Situational factors beyond the control of participants were cited as barriers to pro-environmental actions. Lessons from this study point to the need to carefully study the assumptions underlying intervention strategies aimed at promoting pro-environmental behaviour and to get rid of barriers to enable pro-environmental actions.
- Full Text: false
- Date Issued: 2016
Optical limiting response of multi-walled carbon nanotube-phthalocyanine nanocomposite in solution and when in poly (acrylic acid)
- Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188628 , vital:44770 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.03.067"
- Description: Bis{23-(3,4-di-yloxybenzoic acid)-(2(3), 9(10), 16(17), 23(24)-(hexakis-pyridin-3-yloxy phthalocyaninato)} dineodymium (III) acetate (3) is linked to amino-functionalized multi-walled carbon nanotubes (MWCNT) to form 3-MWCNT. Z-scan technique was employed to experimentally determine the nonlinear absorption coefficient from the open-aperture data. The limiting threshold values as low as 0.045 J cm−2 were found in solution. The conjugate (3-MWCNT) gave better optical limiting behavior than complex 3 alone.
- Full Text:
- Date Issued: 2016
- Authors: Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188628 , vital:44770 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.03.067"
- Description: Bis{23-(3,4-di-yloxybenzoic acid)-(2(3), 9(10), 16(17), 23(24)-(hexakis-pyridin-3-yloxy phthalocyaninato)} dineodymium (III) acetate (3) is linked to amino-functionalized multi-walled carbon nanotubes (MWCNT) to form 3-MWCNT. Z-scan technique was employed to experimentally determine the nonlinear absorption coefficient from the open-aperture data. The limiting threshold values as low as 0.045 J cm−2 were found in solution. The conjugate (3-MWCNT) gave better optical limiting behavior than complex 3 alone.
- Full Text:
- Date Issued: 2016
Molecular identification of Azolla invasions in Africa: The Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist
- Madeira, P T, Dray, F Allen, Coetzee, Julie A, Paterson, Iain D, Tipping, Philip W
- Authors: Madeira, P T , Dray, F Allen , Coetzee, Julie A , Paterson, Iain D , Tipping, Philip W
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424765 , vital:72182 , xlink:href="https://doi.org/10.1016/j.sajb.2016.03.007"
- Description: Biological control of Azolla filiculoides in South Africa with the Azolla specialist Stenopelmus rufinasus has been highly successful. However, field surveys showed that the agent utilized another Azolla species, thought to be the native Azolla pinnata subsp. africana, which contradicted host specificity trials. It is notoriously difficult to determine Azolla species based on morphology so genetic analyses were required to confirm the identity of the Azolla used by the agent. Extensive sampling was conducted and samples were sequenced at the trnL-trnF and trnG-trnR chloroplastic regions and the nuclear ITS1 region. Current literature reported A. filiculoides as the only Section Azolla species in southern Africa but 24 samples were identified as Azolla cristata, an introduced species within Section Azolla that was not used during host specificity trials. A. pinnata subsp. africana was only located at one site in southern Africa, while the alien A. pinnata subsp. asiatica was located at three. What was thought to be A. pinnata subsp. africana was in fact A. cristata, a closer relative of A. filiculoides and a suitable host according to specificity trials. This study confirms that S. rufinasus is a proficient Azolla taxonomist but also supports the use of molecular techniques for resolving taxonomic conundrums.
- Full Text:
- Date Issued: 2016
- Authors: Madeira, P T , Dray, F Allen , Coetzee, Julie A , Paterson, Iain D , Tipping, Philip W
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424765 , vital:72182 , xlink:href="https://doi.org/10.1016/j.sajb.2016.03.007"
- Description: Biological control of Azolla filiculoides in South Africa with the Azolla specialist Stenopelmus rufinasus has been highly successful. However, field surveys showed that the agent utilized another Azolla species, thought to be the native Azolla pinnata subsp. africana, which contradicted host specificity trials. It is notoriously difficult to determine Azolla species based on morphology so genetic analyses were required to confirm the identity of the Azolla used by the agent. Extensive sampling was conducted and samples were sequenced at the trnL-trnF and trnG-trnR chloroplastic regions and the nuclear ITS1 region. Current literature reported A. filiculoides as the only Section Azolla species in southern Africa but 24 samples were identified as Azolla cristata, an introduced species within Section Azolla that was not used during host specificity trials. A. pinnata subsp. africana was only located at one site in southern Africa, while the alien A. pinnata subsp. asiatica was located at three. What was thought to be A. pinnata subsp. africana was in fact A. cristata, a closer relative of A. filiculoides and a suitable host according to specificity trials. This study confirms that S. rufinasus is a proficient Azolla taxonomist but also supports the use of molecular techniques for resolving taxonomic conundrums.
- Full Text:
- Date Issued: 2016
The impact of geographical origin of two strains of the herbivore, Eccritotarsus catarinensis, on several fitness traits in response to temperature
- Ismail, Mohannad, Brooks, Margot
- Authors: Ismail, Mohannad , Brooks, Margot
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66914 , vital:28999 , ISSN 0306-4565 , https://doi.org/10.1016/j.jtherbio.2016.07.008
- Description: Publisher version , Adaptation to temperature changes is vital to reduce adverse effects on individuals, and some may present phenotypic changes, which might be accompanied with physiological costs in fitness traits. The objective of this study was to determine whether the two strains of the herbivore Eccritotarsus catarinensis, a biological control agent against water hyacinth in South Africa, differ in their responses to temperature according to their geographical origin. We experimentally quantified the responses of the two strains, at three constant temperatures: 20 °C, 25 °C and 30 °C, using laboratory cultures that originated from Brazil and Peru, where climates differ. Reproductive output, egg hatching rate, sex ratio and longevity were recorded at each temperature. Fitness traits for both strains were significantly reduced at 30 °C compared with 25 °C and 20 °C in two successive generations. Nonetheless, Peruvian individuals continued their development at 30 °C, whereas Brazilian individuals that succeeded in emerging did not continue their development. In contrast, sex ratio was unaffected by temperature. The Peruvian strain of E. catarinensis presented different phenotypes depending on temperature and was more adapted to extreme high temperature than the Brazilian strain. The tropical origin of the population induces the insect to tolerate the extreme high temperature. We suggest that the Peruvian strain could be better suited for release to control water hyacinth in nature, particularly in regions where temperature is high.
- Full Text: false
- Date Issued: 2016
- Authors: Ismail, Mohannad , Brooks, Margot
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66914 , vital:28999 , ISSN 0306-4565 , https://doi.org/10.1016/j.jtherbio.2016.07.008
- Description: Publisher version , Adaptation to temperature changes is vital to reduce adverse effects on individuals, and some may present phenotypic changes, which might be accompanied with physiological costs in fitness traits. The objective of this study was to determine whether the two strains of the herbivore Eccritotarsus catarinensis, a biological control agent against water hyacinth in South Africa, differ in their responses to temperature according to their geographical origin. We experimentally quantified the responses of the two strains, at three constant temperatures: 20 °C, 25 °C and 30 °C, using laboratory cultures that originated from Brazil and Peru, where climates differ. Reproductive output, egg hatching rate, sex ratio and longevity were recorded at each temperature. Fitness traits for both strains were significantly reduced at 30 °C compared with 25 °C and 20 °C in two successive generations. Nonetheless, Peruvian individuals continued their development at 30 °C, whereas Brazilian individuals that succeeded in emerging did not continue their development. In contrast, sex ratio was unaffected by temperature. The Peruvian strain of E. catarinensis presented different phenotypes depending on temperature and was more adapted to extreme high temperature than the Brazilian strain. The tropical origin of the population induces the insect to tolerate the extreme high temperature. We suggest that the Peruvian strain could be better suited for release to control water hyacinth in nature, particularly in regions where temperature is high.
- Full Text: false
- Date Issued: 2016
Distribution and ecological assessment of heavy metals in irrigation channel sediments in a typical rural area of south China
- Gu, Chiming, Liu, Yi, Li, Zhiguo, Mohamed, Ibrahim, Zhang, Ronghua, Brooks, Margot, Chen, Fang
- Authors: Gu, Chiming , Liu, Yi , Li, Zhiguo , Mohamed, Ibrahim , Zhang, Ronghua , Brooks, Margot , Chen, Fang
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66924 , vital:29000 , ISSN 0925-8574 , https://doi.org/10.1016/j.ecoleng.2016.01.054
- Description: Publisher version , Elevated levels of heavy metals in sediments of irrigation channels can pose risks for crops and livestock, as well as for human health. In this study sediment samples were collected from the irrigation channel in a typical rural area of south China, and digested, in order to analyze their contents for the presence of heavy metals Cu, Zn, Pb, Cr, Cd, and Ni, as well as the non-metal As, to assess total concentrations and pollution levels. The pollution load index and potential ecological risk index of these elements were utilized to assess contamination levels and ecotoxicity. Our results showed that the concentrations of the 7 elements were in the order of Zn > Ni > Cr > Cu > As > Pb > Cd. With the exception of Cr and Pb, concentrations of elements were higher than their background in soil, especially for Cd (1.79 mg kg−1), As (99.61 mg kg−1) and Ni (142.62 mg kg−1), which were 18.49, 8.89 and 5.30 times their background concentrations, respectively. The whole sampled zone was characterized by medium pollution and had a very high potential ecological risk. The area of arable land presented a medium pollution risk, while areas near to the path or road showed high risk of pollution. The predominant contributors to elevated ecological risk for the whole zone were Cd and As.
- Full Text: false
- Date Issued: 2016
- Authors: Gu, Chiming , Liu, Yi , Li, Zhiguo , Mohamed, Ibrahim , Zhang, Ronghua , Brooks, Margot , Chen, Fang
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66924 , vital:29000 , ISSN 0925-8574 , https://doi.org/10.1016/j.ecoleng.2016.01.054
- Description: Publisher version , Elevated levels of heavy metals in sediments of irrigation channels can pose risks for crops and livestock, as well as for human health. In this study sediment samples were collected from the irrigation channel in a typical rural area of south China, and digested, in order to analyze their contents for the presence of heavy metals Cu, Zn, Pb, Cr, Cd, and Ni, as well as the non-metal As, to assess total concentrations and pollution levels. The pollution load index and potential ecological risk index of these elements were utilized to assess contamination levels and ecotoxicity. Our results showed that the concentrations of the 7 elements were in the order of Zn > Ni > Cr > Cu > As > Pb > Cd. With the exception of Cr and Pb, concentrations of elements were higher than their background in soil, especially for Cd (1.79 mg kg−1), As (99.61 mg kg−1) and Ni (142.62 mg kg−1), which were 18.49, 8.89 and 5.30 times their background concentrations, respectively. The whole sampled zone was characterized by medium pollution and had a very high potential ecological risk. The area of arable land presented a medium pollution risk, while areas near to the path or road showed high risk of pollution. The predominant contributors to elevated ecological risk for the whole zone were Cd and As.
- Full Text: false
- Date Issued: 2016
Optically active BODIPYs
- Lu, Hua, Mack, John, Nyokong, Tebello, Kobayashi, Nagao, Shen, Zhen
- Authors: Lu, Hua , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240421 , vital:50833 , xlink:href="https://doi.org/10.1016/j.ccr.2016.03.015"
- Description: This review highlights and summarizes various optically active BODIPY molecules and describes the analysis of their circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy, to provide a platform for the rational design of novel optically active BODIPY structures and the development of new chiroptical applications. Possible future research directions are also discussed.
- Full Text:
- Date Issued: 2016
- Authors: Lu, Hua , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240421 , vital:50833 , xlink:href="https://doi.org/10.1016/j.ccr.2016.03.015"
- Description: This review highlights and summarizes various optically active BODIPY molecules and describes the analysis of their circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy, to provide a platform for the rational design of novel optically active BODIPY structures and the development of new chiroptical applications. Possible future research directions are also discussed.
- Full Text:
- Date Issued: 2016