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
Enhanced triplet state parameters for zinc carboxy phenoxy phthalocyanine following conjugation to ascorbic acid
- Ogbodu, Racheal O, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189348 , vital:44839 , xlink:href="https://doi.org/10.1016/j.poly.2015.01.032"
- Description: Zinc phthalocyanine bearing four ascorbic acid units (formed via ester bond between zinc carboxy phenoxy phthalocyanines and ascorbic acid) was synthesized and characterized using different spectroscopic methods. The complex (with or without ascorbic acid) was further adsorbed onto single walled carbon nanotubes (SWCNTs) and further characterized using Raman spectroscopy, X-ray diffractometry, transmission electron microscopy and thermogravimetric analysis. The photophysical properties of the complexes were studied. The synthesized complex showed better photophysical properties when compared to the carboxy phenoxy phthalocyanines alone, this is evident in the increase of the triplet quantum yields (ΦT), triplet life-times (τT) and singlet oxygen quantum yields (ΦΔ). The zinc phthalocyanines bearing ascorbic acid showed improved triplet life-times even in the presence of SWCNTs.
- Full Text:
- Date Issued: 2015
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189348 , vital:44839 , xlink:href="https://doi.org/10.1016/j.poly.2015.01.032"
- Description: Zinc phthalocyanine bearing four ascorbic acid units (formed via ester bond between zinc carboxy phenoxy phthalocyanines and ascorbic acid) was synthesized and characterized using different spectroscopic methods. The complex (with or without ascorbic acid) was further adsorbed onto single walled carbon nanotubes (SWCNTs) and further characterized using Raman spectroscopy, X-ray diffractometry, transmission electron microscopy and thermogravimetric analysis. The photophysical properties of the complexes were studied. The synthesized complex showed better photophysical properties when compared to the carboxy phenoxy phthalocyanines alone, this is evident in the increase of the triplet quantum yields (ΦT), triplet life-times (τT) and singlet oxygen quantum yields (ΦΔ). The zinc phthalocyanines bearing ascorbic acid showed improved triplet life-times even in the presence of SWCNTs.
- Full Text:
- Date Issued: 2015
Photodynamic antimicrobial chemotherapy activity of (5, 10, 15, 20-tetrakis (4-(4-carboxyphenycarbonoimidoyl) phenyl) porphyrinato) chloro gallium (III)
- Managa, Muthumuni, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Managa, Muthumuni , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189043 , vital:44811 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.088"
- Description: (5,10,15,20-Tetrakis(4-(4-carboxyphenycarbonoimidoyl)phenyl)porphyrinato) chloro gallium(III) (complex 1) was conjugated to platinum nanoparticles (PtNPs) (represented as 1-PtNPs). The resulting conjugate showed 18 nm red shift in the Soret band when compared to 1 alone. Complex 1 and 1-PtNPs showed promising photodynamic antimicrobial chemotherapy (PACT) activity against Staphylococcus aureus, Escherichia coli and Candida albicans in solution where the log reductions obtained were 4.92, 3.76, and 3.95, respectively for 1-PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 1-PtNPs in DMF while that of 1 was 0.52 in the same solvent. This resulted in improved PACT activity for 1-PtNPs compared to 1 alone.
- Full Text:
- Date Issued: 2015
- Authors: Managa, Muthumuni , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189043 , vital:44811 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.088"
- Description: (5,10,15,20-Tetrakis(4-(4-carboxyphenycarbonoimidoyl)phenyl)porphyrinato) chloro gallium(III) (complex 1) was conjugated to platinum nanoparticles (PtNPs) (represented as 1-PtNPs). The resulting conjugate showed 18 nm red shift in the Soret band when compared to 1 alone. Complex 1 and 1-PtNPs showed promising photodynamic antimicrobial chemotherapy (PACT) activity against Staphylococcus aureus, Escherichia coli and Candida albicans in solution where the log reductions obtained were 4.92, 3.76, and 3.95, respectively for 1-PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 1-PtNPs in DMF while that of 1 was 0.52 in the same solvent. This resulted in improved PACT activity for 1-PtNPs compared to 1 alone.
- Full Text:
- Date Issued: 2015
Photophysical properties gallium octacarboxy phthalocyanines conjugated to CdSe@ ZnS quantum dots
- Tshangana, Charmaine, Nyokong, Tebello
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189055 , vital:44812 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.086"
- Description: L-Glutathione (GSH) capped core CdSe (2.3 nm) and core shell CdSe@ZnS quantum dots (QDs) (3.0 nm and 3.5 nm) were coordinated to gallium octacarboxy phthalocyanine (ClGaPc(COOH)8) to form ClGaPc(COOH)8–QDs conjugates. An efficient transfer of energy from the QDs to the Pcs was demonstrated through Förster resonance energy transfer (FRET), the FRET efficiencies in all cases was above 50%. The photophysical parameters (triplet state and fluorescence quantum yields and lifetimes) were also determined for the conjugates. There was a decrease in the fluorescence lifetimes of ClGaPc(COOH)8 in the presence of all the QDs, due to the heavy atom effect. The triplet quantum yields increased in the conjugates. The lifetimes also became longer for the conjugates compared to Pc alone.
- Full Text:
- Date Issued: 2015
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189055 , vital:44812 , xlink:href="https://doi.org/10.1016/j.saa.2015.06.086"
- Description: L-Glutathione (GSH) capped core CdSe (2.3 nm) and core shell CdSe@ZnS quantum dots (QDs) (3.0 nm and 3.5 nm) were coordinated to gallium octacarboxy phthalocyanine (ClGaPc(COOH)8) to form ClGaPc(COOH)8–QDs conjugates. An efficient transfer of energy from the QDs to the Pcs was demonstrated through Förster resonance energy transfer (FRET), the FRET efficiencies in all cases was above 50%. The photophysical parameters (triplet state and fluorescence quantum yields and lifetimes) were also determined for the conjugates. There was a decrease in the fluorescence lifetimes of ClGaPc(COOH)8 in the presence of all the QDs, due to the heavy atom effect. The triplet quantum yields increased in the conjugates. The lifetimes also became longer for the conjugates compared to Pc alone.
- Full Text:
- Date Issued: 2015
The nonlinear absorption in new lanthanide double decker pyridine-based phthalocyanines in solution and thin films
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189307 , vital:44836 , xlink:href="https://doi.org/10.1016/j.optmat.2015.05.022"
- Description: The optical behavior of bis-{2(3), 9(10), 16(17), 23(24)-(tetrapyridin-4-yloxy phthalocyaninato)} lanthanum (III) (2) and its ytterbium (3) counterpart in dimethyl sulfoxide are presented and compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). We report on the third-order susceptibility, second-order hyperpolarizability and the limiting threshold values. The nonlinear optical limiting threshold values of complexes 2, 3 and 4 showed improvement in the solid state (thin films), with complex 4 giving the best value at 0.033 J cm−2.
- Full Text:
- Date Issued: 2015
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189307 , vital:44836 , xlink:href="https://doi.org/10.1016/j.optmat.2015.05.022"
- Description: The optical behavior of bis-{2(3), 9(10), 16(17), 23(24)-(tetrapyridin-4-yloxy phthalocyaninato)} lanthanum (III) (2) and its ytterbium (3) counterpart in dimethyl sulfoxide are presented and compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). We report on the third-order susceptibility, second-order hyperpolarizability and the limiting threshold values. The nonlinear optical limiting threshold values of complexes 2, 3 and 4 showed improvement in the solid state (thin films), with complex 4 giving the best value at 0.033 J cm−2.
- Full Text:
- Date Issued: 2015
Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4, 6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt (II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
Fluorescence behavior and singlet oxygen generating abilities of aluminum phthalocyanine in the presence of anisotropic gold nanoparticles
- Mthethwa, Thandekile, Nyokong, Tebello
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193598 , vital:45351 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
- Full Text:
- Date Issued: 2015
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193598 , vital:45351 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
- Full Text:
- Date Issued: 2015
Fluorescence behavior and singlet oxygen generating abilities of aluminum phthalocyanine in the presence of anisotropic gold nanoparticles
- Mthethwa, Thandekile, Nyokong, Tebello
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189865 , vital:44941 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
- Full Text:
- Date Issued: 2015
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189865 , vital:44941 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
- Full Text:
- Date Issued: 2015
Transformative, transgressive social learning: Rethinking higher education pedagogy in times of systemic global dysfunction
- Lotz-Sisitka, Heila, Wals, Arjen E J, Kronlid, David O, McGarry, Dylan K
- Authors: Lotz-Sisitka, Heila , Wals, Arjen E J , Kronlid, David O , McGarry, Dylan K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/372794 , vital:66623 , xlink:href="https://doi.org/10.1016/j.cosust.2015.07.018"
- Description: The nature of the sustainability challenges currently at hand is such that dominant pedagogies and forms of learning that characterize higher education need to be reconsidered to enable students and staff to deal with accelerating change, increasing complexity, contested knowledge claims and inevitable uncertainty. In this contribution we identified four streams of emerging transformative, transgressive learning research and praxis in the sustainability sciences that appear generative of a higher education pedagogy that appears more responsive to the key challenges of our time: (1) reflexive social learning and capabilities theory, (2) critical phenomenology, (3) socio-cultural and cultural historical activity theory, and (4) new social movement, postcolonial and decolonisation theory. The paper critiques the current tendency in sustainability science and learning to rely on resilience and adaptive capacity building and argues that in order to break with maladaptive resilience of unsustainable systems it is essential to strengthen transgressive learning and disruptive capacity-building.
- Full Text:
- Date Issued: 2015
- Authors: Lotz-Sisitka, Heila , Wals, Arjen E J , Kronlid, David O , McGarry, Dylan K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/372794 , vital:66623 , xlink:href="https://doi.org/10.1016/j.cosust.2015.07.018"
- Description: The nature of the sustainability challenges currently at hand is such that dominant pedagogies and forms of learning that characterize higher education need to be reconsidered to enable students and staff to deal with accelerating change, increasing complexity, contested knowledge claims and inevitable uncertainty. In this contribution we identified four streams of emerging transformative, transgressive learning research and praxis in the sustainability sciences that appear generative of a higher education pedagogy that appears more responsive to the key challenges of our time: (1) reflexive social learning and capabilities theory, (2) critical phenomenology, (3) socio-cultural and cultural historical activity theory, and (4) new social movement, postcolonial and decolonisation theory. The paper critiques the current tendency in sustainability science and learning to rely on resilience and adaptive capacity building and argues that in order to break with maladaptive resilience of unsustainable systems it is essential to strengthen transgressive learning and disruptive capacity-building.
- Full Text:
- Date Issued: 2015
Transformative, transgressive social learning: Rethinking higher education pedagogy in times of systemic global dysfunction
- Lotz-Sisitka, Heila, Wals, Arjen E, Kronlid, David O, McGarry, Dylan K
- Authors: Lotz-Sisitka, Heila , Wals, Arjen E , Kronlid, David O , McGarry, Dylan K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392190 , vital:68729 , xlink:href="https://doi.org/10.1016/j.cosust.2015.07.018"
- Description: The nature of the sustainability challenges currently at hand is such that dominant pedagogies and forms of learning that characterize higher education need to be reconsidered to enable students and staff to deal with accelerating change, increasing complexity, contested knowledge claims and inevitable uncertainty. In this contribution we identified four streams of emerging transformative, transgressive learning research and praxis in the sustainability sciences that appear generative of a higher education pedagogy that appears more responsive to the key challenges of our time: (1) reflexive social learning and capabilities theory, (2) critical phenomenology, (3) socio-cultural and cultural historical activity theory, and (4) new social movement, postcolonial and decolonisation theory. The paper critiques the current tendency in sustainability science and learning to rely on resilience and adaptive capacity building and argues that in order to break with maladaptive resilience of unsustainable systems it is essential to strengthen transgressive learning and disruptive capacity-building.
- Full Text:
- Date Issued: 2015
- Authors: Lotz-Sisitka, Heila , Wals, Arjen E , Kronlid, David O , McGarry, Dylan K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392190 , vital:68729 , xlink:href="https://doi.org/10.1016/j.cosust.2015.07.018"
- Description: The nature of the sustainability challenges currently at hand is such that dominant pedagogies and forms of learning that characterize higher education need to be reconsidered to enable students and staff to deal with accelerating change, increasing complexity, contested knowledge claims and inevitable uncertainty. In this contribution we identified four streams of emerging transformative, transgressive learning research and praxis in the sustainability sciences that appear generative of a higher education pedagogy that appears more responsive to the key challenges of our time: (1) reflexive social learning and capabilities theory, (2) critical phenomenology, (3) socio-cultural and cultural historical activity theory, and (4) new social movement, postcolonial and decolonisation theory. The paper critiques the current tendency in sustainability science and learning to rely on resilience and adaptive capacity building and argues that in order to break with maladaptive resilience of unsustainable systems it is essential to strengthen transgressive learning and disruptive capacity-building.
- Full Text:
- Date Issued: 2015
Nanosecond nonlinear optical limiting properties of new trinuclear lanthanide phthalocyanines in solution and as thin films
- Sekhosana, Kutloana E, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189752 , vital:44928 , xlink:href="https://doi.org/10.1016/j.poly.2014.08.047"
- Description: 2,4,6-Tris[3-thio-9,10,16,17,23,24-hexa(4-tertbutylphenoxy) phthalocyaninato ytterbium (III) chloride]-s-triazin (3) and its lutetium counterpart (4) were synthesized. The nonlinear optical behavior of 3 and 4 were characterized in solution and when embedded in polymer as thin films. Thin films of complexes 3 and 4 in poly(bisphenol A carbonate) showed improved nonlinear optical properties when compared to solution. Complex 3 showed a lower threshold for optical limiting intensity (Ilim) than complex 4, and for phthalocyanines in general. Ilim values were even lower in films compared to solutions.
- Full Text:
- Date Issued: 2015
- Authors: Sekhosana, Kutloana E , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189752 , vital:44928 , xlink:href="https://doi.org/10.1016/j.poly.2014.08.047"
- Description: 2,4,6-Tris[3-thio-9,10,16,17,23,24-hexa(4-tertbutylphenoxy) phthalocyaninato ytterbium (III) chloride]-s-triazin (3) and its lutetium counterpart (4) were synthesized. The nonlinear optical behavior of 3 and 4 were characterized in solution and when embedded in polymer as thin films. Thin films of complexes 3 and 4 in poly(bisphenol A carbonate) showed improved nonlinear optical properties when compared to solution. Complex 3 showed a lower threshold for optical limiting intensity (Ilim) than complex 4, and for phthalocyanines in general. Ilim values were even lower in films compared to solutions.
- Full Text:
- Date Issued: 2015
Synthetic analogues of the marine bisindole deoxytopsentin: potent selective inhibitors of MRSA pyruvate kinase
- Veale, Clinton G L, Zoraghi, Roya, Young, Ryan M, Morrison, James P, Pretheeban, Manoj, Lobb, Kevin A, Reiner, Neil E, Andersen, Raymond J, Davies-Coleman, Michael T
- Authors: Veale, Clinton G L , Zoraghi, Roya , Young, Ryan M , Morrison, James P , Pretheeban, Manoj , Lobb, Kevin A , Reiner, Neil E , Andersen, Raymond J , Davies-Coleman, Michael T
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448045 , vital:74693 , xlink:href="https://doi.org/10.1021/np500755v"
- Description: As part of an ongoing study to elucidate the SAR of bisindole alkaloid inhibitors against the evolutionary conserved MRSA pyruvate kinase (PK), we present here the synthesis and biological activity of six dihalogenated analogues of the naturally occurring sponge metabolite deoxytopsentin, including the naturally occurring dibromodeoxytopsentin. The most active compounds displayed potent low nanomolar inhibitory activity against MRSA PK with concomitant significant selectivity for MRSA PK over human PK orthologues. Computational studies suggest that these potent MRSA PK inhibitors occupy a region of the small interface of the enzyme tetramer where amino acid sequence divergence from common human PK orthologues may contribute to the observed selectivity.
- Full Text:
- Date Issued: 2015
- Authors: Veale, Clinton G L , Zoraghi, Roya , Young, Ryan M , Morrison, James P , Pretheeban, Manoj , Lobb, Kevin A , Reiner, Neil E , Andersen, Raymond J , Davies-Coleman, Michael T
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448045 , vital:74693 , xlink:href="https://doi.org/10.1021/np500755v"
- Description: As part of an ongoing study to elucidate the SAR of bisindole alkaloid inhibitors against the evolutionary conserved MRSA pyruvate kinase (PK), we present here the synthesis and biological activity of six dihalogenated analogues of the naturally occurring sponge metabolite deoxytopsentin, including the naturally occurring dibromodeoxytopsentin. The most active compounds displayed potent low nanomolar inhibitory activity against MRSA PK with concomitant significant selectivity for MRSA PK over human PK orthologues. Computational studies suggest that these potent MRSA PK inhibitors occupy a region of the small interface of the enzyme tetramer where amino acid sequence divergence from common human PK orthologues may contribute to the observed selectivity.
- Full Text:
- Date Issued: 2015
Physicochemical and photodynamic antimicrobial chemotherapy studies of mono-and tetra-pyridyloxy substituted indium (III) phthalocyanines
- Osifeko, Olawale L, Durmus, Mahmut, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Durmus, Mahmut , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189547 , vital:44856 , xlink:href="https://doi.org/10.1016/j.jphotochem.2014.12.011"
- Description: The synthesis and photophysicochemical properties of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines (InPcs) are presented in this study. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of these compounds. The complexes exhibited high singlet oxygen quantum yields (ФΔ) ranging from 0.44 to 0.66 in DMF, and from 0.44 to 0.69 in DMSO and ФΔ = 0.31 for the quartenized tetra substituted InPc which is soluble in water. The triplet quantum yields (ФT) ranged from 0.77 to 0.95 in DMF and from 0.77 to 0.94) in DMSO. The tetra substituted photosensitizers do not differ in their inactivation of bacteria with over 8 log reduction of viable bacteria when compared with the mono substituted photosensitizer which could only manage a 1 log reduction.
- Full Text:
- Date Issued: 2015
- Authors: Osifeko, Olawale L , Durmus, Mahmut , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189547 , vital:44856 , xlink:href="https://doi.org/10.1016/j.jphotochem.2014.12.011"
- Description: The synthesis and photophysicochemical properties of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines (InPcs) are presented in this study. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of these compounds. The complexes exhibited high singlet oxygen quantum yields (ФΔ) ranging from 0.44 to 0.66 in DMF, and from 0.44 to 0.69 in DMSO and ФΔ = 0.31 for the quartenized tetra substituted InPc which is soluble in water. The triplet quantum yields (ФT) ranged from 0.77 to 0.95 in DMF and from 0.77 to 0.94) in DMSO. The tetra substituted photosensitizers do not differ in their inactivation of bacteria with over 8 log reduction of viable bacteria when compared with the mono substituted photosensitizer which could only manage a 1 log reduction.
- Full Text:
- Date Issued: 2015
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