Physicochemical and photodynamic antimicrobial chemotherapy studies of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines
- Osifeko, Olawale L, Durmuş, Mahmut, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Durmuş, Mahmut , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7255 , http://hdl.handle.net/10962/d1020264 , http://dx.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. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2014.12.011
- Full Text: false
- Date Issued: 2015
- Authors: Osifeko, Olawale L , Durmuş, Mahmut , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7255 , http://hdl.handle.net/10962/d1020264 , http://dx.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. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2014.12.011
- Full Text: false
- Date Issued: 2015
Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
The improved antibacterial efficiency of a zinc phthalocyanine when embedded on silver nanoparticle modified silica nanofibers
- Mapukata, Sivuyisiwe, Britton, Jonathan, Osifeko, Olawale L, Nyokong, Tebello
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
Physicochemical and photodynamic antimicrobial chemotherapy studies of mono-and tetra-pyridyloxy substituted indium (III) phthalocyanines
- Osifeko, Olawale, Durmus, Mahmut, Nyokong, Tebello
- Authors: Osifeko, Olawale , 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 , 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
Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189898 , vital:44945 , xlink:href="https://doi.org/10.1016/j.dyepig.2014.05.010"
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli.
- Full Text:
- Date Issued: 2014
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189898 , vital:44945 , xlink:href="https://doi.org/10.1016/j.dyepig.2014.05.010"
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli.
- Full Text:
- Date Issued: 2014
The antibacterial and antifungal properties of neutral, octacationic and hexadecacationic Zn phthalocyanines when conjugated to silver nanoparticles
- Mapukata, Sibusisiwe, Sen, Pinar, Osifeko, Olawale L, Nyokong, Tebello
- Authors: Mapukata, Sibusisiwe , Sen, Pinar , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185667 , vital:44408 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102361"
- Description: The syntheses and characterization of novel octacationic and hexadecacationic Pcs is reported. With the aim of enhancing singlet oxygen generation efficiencies and hence antimicrobial activities, these Pcs (including their neutral counterpart) are conjugated to Ag nanoparticles (AgNPs). The obtained results show that the conjugate composed of the neutral Pc has a higher loading of Pcs as well as a greater singlet oxygen quantum yield enhancement (in the presence of AgNPs) in DMSO. The antimicrobial efficiencies of the Pcs and their conjugates were evaluated and compared on S. aureus, E. coli and C. albicans. The cationic Pcs possess better activity than the neutral Pc against all the microorganisms with the hexadecacationic Pc being the best. This work therefore demonstrates that increase in the number of cationic charges on the reported Pcs results in enhanced antimicrobial activities, which is maintained even when conjugated to Ag nanoparticles. The high activity and lack of selectivity of the cationic Pcs when conjugated to Ag NPs against different microorganisms make them good candidates for real life antimicrobial treatments.
- Full Text:
- Date Issued: 2021
- Authors: Mapukata, Sibusisiwe , Sen, Pinar , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185667 , vital:44408 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102361"
- Description: The syntheses and characterization of novel octacationic and hexadecacationic Pcs is reported. With the aim of enhancing singlet oxygen generation efficiencies and hence antimicrobial activities, these Pcs (including their neutral counterpart) are conjugated to Ag nanoparticles (AgNPs). The obtained results show that the conjugate composed of the neutral Pc has a higher loading of Pcs as well as a greater singlet oxygen quantum yield enhancement (in the presence of AgNPs) in DMSO. The antimicrobial efficiencies of the Pcs and their conjugates were evaluated and compared on S. aureus, E. coli and C. albicans. The cationic Pcs possess better activity than the neutral Pc against all the microorganisms with the hexadecacationic Pc being the best. This work therefore demonstrates that increase in the number of cationic charges on the reported Pcs results in enhanced antimicrobial activities, which is maintained even when conjugated to Ag nanoparticles. The high activity and lack of selectivity of the cationic Pcs when conjugated to Ag NPs against different microorganisms make them good candidates for real life antimicrobial treatments.
- Full Text:
- Date Issued: 2021
Enhanced nonlinear optical responses of zinc diaminopyrimidin-2-ylthio phthalocyanine conjugated to AgxAuy alloy nanoparticles
- Bankole, Owolabi M, Osifeko, Olawale, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240382 , vital:50829 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.06.025"
- Description: In this article, the photophysical and nonlinear optical (NLO) characterizations of diaminopyrimidin-2-ylthio phthalocyaninatozinc (II) (2) before and after conjugation to AgxAuy nano-alloys are discussed. Phthalocyanines-AgxAuy (2-AgxAuy) composites showed enhanced triplet state and nonlinear optical behaviour when compared to free phthalocyanine. Optical limiting (OL) responses of the samples were evaluated using Z-scan technique at 532 nm and 10 ns in dimethyl sulfoxide. Reverse saturable absorption (RSA), which is a direct consequence of triplet absorption of already excited molecules was observed as the dominant mechanism responsible for nonlinearity of the samples. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, 2-AgxAuy composites were found to exhibit stronger optical limiting responses than unconjugated phthalocyanine. The large third-order susceptibilities of the composites make them suitable materials for attenuating modern laser radiations, and also found useful in various optical applications.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240382 , vital:50829 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.06.025"
- Description: In this article, the photophysical and nonlinear optical (NLO) characterizations of diaminopyrimidin-2-ylthio phthalocyaninatozinc (II) (2) before and after conjugation to AgxAuy nano-alloys are discussed. Phthalocyanines-AgxAuy (2-AgxAuy) composites showed enhanced triplet state and nonlinear optical behaviour when compared to free phthalocyanine. Optical limiting (OL) responses of the samples were evaluated using Z-scan technique at 532 nm and 10 ns in dimethyl sulfoxide. Reverse saturable absorption (RSA), which is a direct consequence of triplet absorption of already excited molecules was observed as the dominant mechanism responsible for nonlinearity of the samples. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, 2-AgxAuy composites were found to exhibit stronger optical limiting responses than unconjugated phthalocyanine. The large third-order susceptibilities of the composites make them suitable materials for attenuating modern laser radiations, and also found useful in various optical applications.
- Full Text:
- Date Issued: 2016
Synthesis and physicochemical properties of zinc and indium phthalocyanines conjugated to quantum dots, gold and magnetic nanoparticles
- Osifeko, Olawale, Nyokong, Tebello
- Authors: Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188639 , vital:44771 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.04.015"
- Description: This work reports on the conjugation of semiconductors quantum dots (QDs), gold (AuNPs) or Fe3O4 magnetic (MNPs) nanoparticles to 4-(4,6-diaminopyrimidin-2-ylthio) substituted indium or zinc phthalocyanines (Pcs). The QDs and MNPs were linked to the Pcs via an amide bond and by chemisorption unto AuNP surface. There is a general decrease in fluorescence quantum yields of the Pcs in the presence of all the nanoparticles. There is an increase triplet quantum yields for Pcs in the presence of AuNPs and QDs, but not in the presence of MNPs. AuNPs conjugates irrespective of the central atoms have the highest singlet oxygen quantum yield and are more photo-stable than all the other conjugates. MPcs are less photostable in the presence of MNPs.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188639 , vital:44771 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.04.015"
- Description: This work reports on the conjugation of semiconductors quantum dots (QDs), gold (AuNPs) or Fe3O4 magnetic (MNPs) nanoparticles to 4-(4,6-diaminopyrimidin-2-ylthio) substituted indium or zinc phthalocyanines (Pcs). The QDs and MNPs were linked to the Pcs via an amide bond and by chemisorption unto AuNP surface. There is a general decrease in fluorescence quantum yields of the Pcs in the presence of all the nanoparticles. There is an increase triplet quantum yields for Pcs in the presence of AuNPs and QDs, but not in the presence of MNPs. AuNPs conjugates irrespective of the central atoms have the highest singlet oxygen quantum yield and are more photo-stable than all the other conjugates. MPcs are less photostable in the presence of MNPs.
- Full Text:
- Date Issued: 2016
Bacterial degradation of coal discard and geologically weathered coal:
- Olawale, Jacob T, Edeki, Oghenekume G, Cowan, Keith A
- Authors: Olawale, Jacob T , Edeki, Oghenekume G , Cowan, Keith A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178694 , vital:40097 , https://doi.org/10.1007/s40789-020-00306-3
- Description: The biodegradation of coal discard is being intensively studied in South Africa in an effort to develop passive methods for the successful revegetation and rehabilitation of waste dumps, to mitigate pollution, and facilitate mine closure. Bacteria were isolated from slurries of coal tailings and diesel-contaminated soil, screened for coal biodegradation competence, characterized, and the colonization and degradation of coal discard and geologically weathered coal investigated using individual isolates and consortia. Ten novel coal-degrading bacterial strains were isolated and characterized, the gene sequences deposited with GenBank, and the (wild-type) strains deposited at Microbial Culture Collection, India.
- Full Text:
- Date Issued: 2020
- Authors: Olawale, Jacob T , Edeki, Oghenekume G , Cowan, Keith A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178694 , vital:40097 , https://doi.org/10.1007/s40789-020-00306-3
- Description: The biodegradation of coal discard is being intensively studied in South Africa in an effort to develop passive methods for the successful revegetation and rehabilitation of waste dumps, to mitigate pollution, and facilitate mine closure. Bacteria were isolated from slurries of coal tailings and diesel-contaminated soil, screened for coal biodegradation competence, characterized, and the colonization and degradation of coal discard and geologically weathered coal investigated using individual isolates and consortia. Ten novel coal-degrading bacterial strains were isolated and characterized, the gene sequences deposited with GenBank, and the (wild-type) strains deposited at Microbial Culture Collection, India.
- Full Text:
- Date Issued: 2020
Synthesis, photophysicochemical and photodynamic antimicrobial chemotherapy studies of indium pyridyl phthalocyanines: Charge versus bridging atom
- Sindelo, Azole, Nyokong, Tebello
- Authors: Sindelo, Azole , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187650 , vital:44683 , xlink:href="https://doi.org/10.1016/j.ica.2018.02.020"
- Description: 2(3), 9(10), 16(17), 23(24)-Octapyridylsulfanyl phthalocyaninato chloroindium(III) (complex 1a) and its quaternized derivative 2(3), 9(10), 16(17), 23(24)-octamethylpyridylsulfanyl phthalocyaninato chloroindium (III) (complex 1b) were synthesised. The triplet quantum yields were 0.53 and 0.48 while the singlet oxygen quantum yields were 0.46 and 0.33 in DMF for 1a and 1b, respectively. The photodynamic antimicrobial chemotherapy (PACT) activity of 1b (containing 8 positive charges) was compared to those of 9(10),16(17),23(24)-tri-N-methyl-4-pyridylsulfanyl-2(3)-(4-aminophenoxy) phthalocyaninato chloro indium(III) triiodide (2) (containing 3 positive charges) and 2-[4-(N-Methylpyridyloxy) phthalocyaninato] chloroindium (III) iodide (3) (containing 4 positive charges). Complex 1b gave log reductions of 4.21, 8.30 and 3.21 for Gram(−) E. coli, Gram(+) S. aureus and C. albicans, respectively. When comparing 1b, 2 and 3, the largest log reductions for E. coli were obtained for complex 3 containing four positive charges hence showing it is not always the charge that determines the PACT activity, but the bridging atom in the phthalocyanine plays a role.
- Full Text:
- Date Issued: 2018
- Authors: Sindelo, Azole , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187650 , vital:44683 , xlink:href="https://doi.org/10.1016/j.ica.2018.02.020"
- Description: 2(3), 9(10), 16(17), 23(24)-Octapyridylsulfanyl phthalocyaninato chloroindium(III) (complex 1a) and its quaternized derivative 2(3), 9(10), 16(17), 23(24)-octamethylpyridylsulfanyl phthalocyaninato chloroindium (III) (complex 1b) were synthesised. The triplet quantum yields were 0.53 and 0.48 while the singlet oxygen quantum yields were 0.46 and 0.33 in DMF for 1a and 1b, respectively. The photodynamic antimicrobial chemotherapy (PACT) activity of 1b (containing 8 positive charges) was compared to those of 9(10),16(17),23(24)-tri-N-methyl-4-pyridylsulfanyl-2(3)-(4-aminophenoxy) phthalocyaninato chloro indium(III) triiodide (2) (containing 3 positive charges) and 2-[4-(N-Methylpyridyloxy) phthalocyaninato] chloroindium (III) iodide (3) (containing 4 positive charges). Complex 1b gave log reductions of 4.21, 8.30 and 3.21 for Gram(−) E. coli, Gram(+) S. aureus and C. albicans, respectively. When comparing 1b, 2 and 3, the largest log reductions for E. coli were obtained for complex 3 containing four positive charges hence showing it is not always the charge that determines the PACT activity, but the bridging atom in the phthalocyanine plays a role.
- Full Text:
- Date Issued: 2018
Effects of symmetry and the number of positive charges on the photocatalytic activity of indium phthalocyanines when embedded in electrospun fibers
- Chakona, Gamuchirai, Nyokong, Tebello
- Authors: Chakona, Gamuchirai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188304 , vital:44743 , xlink:href="https://doi.org/10.1016/j.ica.2016.12.025"
- Description: Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric indium(III) phthalocyanines photosensitizers: the first consisting of one quaternized 4-pyridyloxyl and no other substituents (complex 1) and the second containing three quaternized 4-pyridylsulfanyl units and one aminophenoxy (complex 3). The asymmetry of complex 3 is additionally caused by the presence of two linking atoms (O and S). The symmetrically substituted indium(III) phthalocyanine containing four quaternized 4-pyridyloxyl units (complex 2) was also studied. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalytic transformation of 4-chlorophenol and bisphenol A. When immobilized on electrospun fibers, complexes 1, 2 and 3 gave singlet oxygen values of 0.31, 0.39 and 0.50 in water, respectively. Complex 3 showed the best photocatalytic behavior with observed rate constants of 2.8 × 10−3 min−1 for bisphenol A and 3.8 × 10−3 min−1 for 4-chlorophenol.
- Full Text:
- Date Issued: 2017
- Authors: Chakona, Gamuchirai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188304 , vital:44743 , xlink:href="https://doi.org/10.1016/j.ica.2016.12.025"
- Description: Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric indium(III) phthalocyanines photosensitizers: the first consisting of one quaternized 4-pyridyloxyl and no other substituents (complex 1) and the second containing three quaternized 4-pyridylsulfanyl units and one aminophenoxy (complex 3). The asymmetry of complex 3 is additionally caused by the presence of two linking atoms (O and S). The symmetrically substituted indium(III) phthalocyanine containing four quaternized 4-pyridyloxyl units (complex 2) was also studied. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalytic transformation of 4-chlorophenol and bisphenol A. When immobilized on electrospun fibers, complexes 1, 2 and 3 gave singlet oxygen values of 0.31, 0.39 and 0.50 in water, respectively. Complex 3 showed the best photocatalytic behavior with observed rate constants of 2.8 × 10−3 min−1 for bisphenol A and 3.8 × 10−3 min−1 for 4-chlorophenol.
- Full Text:
- Date Issued: 2017
A comparative physicochemical study of unsymmetrical indium phthalocyanines in the presence of magnetic nanoparticles or quantum dots
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
Post -war recovery and development in Liberia since 2013
- Authors: Mbulle-Nziege, Leonard
- Date: 2016
- Subjects: Postwar reconstruction -- Liberia Liberia -- Politics and government -- 21st century , Peace-building
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12361 , vital:27058
- Description: The aims and objectives of this study are notably, to provide an overall understanding of the history of Liberia, from the country’s foundation, through the civil war, up to the present day post-conflict scenario. It intends to identify the strategies and schemes put in place by Liberian officials and other stakeholders, while outlining the importance of attaining the goals attached to these various plans. The difficulties of achieving these post-conflict development goals will also be noted, and finally, It analyses whether the concepts used in Liberia might also be implemented in post-conflict societies not only in Africa, but all over the world.
- Full Text:
- Date Issued: 2016
- Authors: Mbulle-Nziege, Leonard
- Date: 2016
- Subjects: Postwar reconstruction -- Liberia Liberia -- Politics and government -- 21st century , Peace-building
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12361 , vital:27058
- Description: The aims and objectives of this study are notably, to provide an overall understanding of the history of Liberia, from the country’s foundation, through the civil war, up to the present day post-conflict scenario. It intends to identify the strategies and schemes put in place by Liberian officials and other stakeholders, while outlining the importance of attaining the goals attached to these various plans. The difficulties of achieving these post-conflict development goals will also be noted, and finally, It analyses whether the concepts used in Liberia might also be implemented in post-conflict societies not only in Africa, but all over the world.
- Full Text:
- Date Issued: 2016
The factors that influence the scalability of tenderpreneurs
- Authors: Ngwane, Amanda
- Date: 2019
- Subjects: Entrepreneurship -- South Africa , Small business -- South Africa Corporations -- South Africa -- Growth Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/41841 , vital:36602
- Description: This study investigated the scalability of tenderpreneurs in South Africa. The South African government has invested a lot of capital towards small and medium-sized enterprises (SMEs), through the tender system. The unemployment trend in the country continues and is a reflection of symptoms and problems that impede the effectiveness of government initiatives such as the tender system. The main aim of this study was to establish the factors influencing the scalability of tenderpreneurs in South Africa. Further objectives intended to establish the factors that would enable tenderpreneurs to scale their businesses, to define the characteristics of a tenderpreneur in South Africa, to determine the factors that influence the growth of tenderpreneurs in South Africa and to establish the strengths, weaknesses, opportunities for and threats to the scalability of tenderpreneurs in South Africa. In order to achieve the said objectives, a sample of ten tenderpreneurs from the Ilembe District in KwaZulu-Natal, was selected from an estimated population of over 50 tenderpreneurs in the region, using the convenience sampling technique. The phenomenological paradigm was employed and qualitative research was done using the exploratory research design. Semi-structured interviews were used to collect data for the study. The findings of this study characterised a tenderpreneur as an individual bent on providing requested services, engaging in competitive bidding, usually awaiting opportunities or bids, who do business with or without prior capital. In the political front, the advent of the end of the apartheid era, the emergence of the democratic movement and emancipation of the black majority contributed to the drive towards business ownership by the previously disadvantaged groups. Recommendations made included the fact that the relevant government authorities should assist in supporting the tenderpreneurs through a number of policy and political initiatives such as ensuring broader stakeholder participation, fostering established public funded partnerships, mainstreaming corporate social investment to uplift communities, enforce sustainable business practices and drive infrastructure development.
- Full Text:
- Date Issued: 2019
- Authors: Ngwane, Amanda
- Date: 2019
- Subjects: Entrepreneurship -- South Africa , Small business -- South Africa Corporations -- South Africa -- Growth Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/41841 , vital:36602
- Description: This study investigated the scalability of tenderpreneurs in South Africa. The South African government has invested a lot of capital towards small and medium-sized enterprises (SMEs), through the tender system. The unemployment trend in the country continues and is a reflection of symptoms and problems that impede the effectiveness of government initiatives such as the tender system. The main aim of this study was to establish the factors influencing the scalability of tenderpreneurs in South Africa. Further objectives intended to establish the factors that would enable tenderpreneurs to scale their businesses, to define the characteristics of a tenderpreneur in South Africa, to determine the factors that influence the growth of tenderpreneurs in South Africa and to establish the strengths, weaknesses, opportunities for and threats to the scalability of tenderpreneurs in South Africa. In order to achieve the said objectives, a sample of ten tenderpreneurs from the Ilembe District in KwaZulu-Natal, was selected from an estimated population of over 50 tenderpreneurs in the region, using the convenience sampling technique. The phenomenological paradigm was employed and qualitative research was done using the exploratory research design. Semi-structured interviews were used to collect data for the study. The findings of this study characterised a tenderpreneur as an individual bent on providing requested services, engaging in competitive bidding, usually awaiting opportunities or bids, who do business with or without prior capital. In the political front, the advent of the end of the apartheid era, the emergence of the democratic movement and emancipation of the black majority contributed to the drive towards business ownership by the previously disadvantaged groups. Recommendations made included the fact that the relevant government authorities should assist in supporting the tenderpreneurs through a number of policy and political initiatives such as ensuring broader stakeholder participation, fostering established public funded partnerships, mainstreaming corporate social investment to uplift communities, enforce sustainable business practices and drive infrastructure development.
- Full Text:
- Date Issued: 2019
Strategic planning as a tool for investment decision-making for SMEs in Nelson Mandela Metropole
- Authors: Kikine, Bereng Nimrode
- Date: 2013
- Subjects: Small business -- Management , Strategic planning
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6455 , vital:21092
- Description: All around the world, SMEs are perceived as the engine room of economic growth, job creation and poverty alleviation, due to their flexibility and quick adaptability to change. It is believed that, for developing countries to address their social and economic challenges, it would be beneficial if they leverage the potential that the SME sector potentially possess. However, despite the government focus on supporting and encouraging the establishment of SMEs through the small business development programmes in order to address these social challenges, SME sector has experienced a high degree of business mortality, which impacts negatively on the ability to create sustainable employment opportunities in the long term. This view is supported by the work of (Ligthelm and Cant 2003). According to the global economic monitor (GEM), the small business mortality in South Africa is among the highest in the world. It is said that that most newly established SMEs will not survive beyond 48 months Von Broembsen, as cited in Olawale and Garwe (2010: 730). One of the reasons that lead to the high failure rate of SMEs is the lack of strategic planning and the poor allocation of resources. The literature review suggests that SMEs that embark on strategic planning are the ones that are most likely to experience sales growth, personnel growth and asset value growth, as opposed those that do not do any strategic planning at all. The primary objective of this research was to establish how a strategic planning process can be used as an investment decision-making tool for manufacturing SMEs in the Nelson Mandela Metropole. In order to address this research problem, the following sub-problems had to be solved: - What strategic planning processes do current SME managers use? - What strategic performance measurement systems do SME owner-managers currently use? - What capital budgeting techniques are currently being used by SME’s in the region? - How do SME owner-managers evaluate the risk of the projects at hand? The research design was methodological triangulation in nature, that is, using both qualitative and quantitative methodologies, though a quantitative paradigm was more dominant that the qualitative paradigm. A questionnaire was designed as a primary source of data collection from a selected sample group. The empirical study revealed that there is some level of strategic planning amongst SMEs, however, it is mostly informal and unstructured. It also emerged that strategic planning can be used as more than just a performance measurement tool, it can contribute more effectively to strategic alignment, organisational learning and diffusion of knowledge throughout the organisation. The empirical study also suggests that SMEs understand that capital budgeting is critical for the success of the organisations. However, very few SMEs have a formal capital budgeting process. It also became evident that most SMEs are still relying on the traditional capital budgeting techniques; that is, ‘gut feel’ and the payback methods of evaluating projects. The empirical study suggests that the largest group of SMEs rely on break-even analysis and scenario planning as the major indicators of the impact the projects will or may have on the organisation. The recommendations have thus been made to address the challenges facing SMEs with regard to strategic planning, strategic performance measurement, capital budgeting and project risk evaluation.
- Full Text:
- Date Issued: 2013
- Authors: Kikine, Bereng Nimrode
- Date: 2013
- Subjects: Small business -- Management , Strategic planning
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6455 , vital:21092
- Description: All around the world, SMEs are perceived as the engine room of economic growth, job creation and poverty alleviation, due to their flexibility and quick adaptability to change. It is believed that, for developing countries to address their social and economic challenges, it would be beneficial if they leverage the potential that the SME sector potentially possess. However, despite the government focus on supporting and encouraging the establishment of SMEs through the small business development programmes in order to address these social challenges, SME sector has experienced a high degree of business mortality, which impacts negatively on the ability to create sustainable employment opportunities in the long term. This view is supported by the work of (Ligthelm and Cant 2003). According to the global economic monitor (GEM), the small business mortality in South Africa is among the highest in the world. It is said that that most newly established SMEs will not survive beyond 48 months Von Broembsen, as cited in Olawale and Garwe (2010: 730). One of the reasons that lead to the high failure rate of SMEs is the lack of strategic planning and the poor allocation of resources. The literature review suggests that SMEs that embark on strategic planning are the ones that are most likely to experience sales growth, personnel growth and asset value growth, as opposed those that do not do any strategic planning at all. The primary objective of this research was to establish how a strategic planning process can be used as an investment decision-making tool for manufacturing SMEs in the Nelson Mandela Metropole. In order to address this research problem, the following sub-problems had to be solved: - What strategic planning processes do current SME managers use? - What strategic performance measurement systems do SME owner-managers currently use? - What capital budgeting techniques are currently being used by SME’s in the region? - How do SME owner-managers evaluate the risk of the projects at hand? The research design was methodological triangulation in nature, that is, using both qualitative and quantitative methodologies, though a quantitative paradigm was more dominant that the qualitative paradigm. A questionnaire was designed as a primary source of data collection from a selected sample group. The empirical study revealed that there is some level of strategic planning amongst SMEs, however, it is mostly informal and unstructured. It also emerged that strategic planning can be used as more than just a performance measurement tool, it can contribute more effectively to strategic alignment, organisational learning and diffusion of knowledge throughout the organisation. The empirical study also suggests that SMEs understand that capital budgeting is critical for the success of the organisations. However, very few SMEs have a formal capital budgeting process. It also became evident that most SMEs are still relying on the traditional capital budgeting techniques; that is, ‘gut feel’ and the payback methods of evaluating projects. The empirical study suggests that the largest group of SMEs rely on break-even analysis and scenario planning as the major indicators of the impact the projects will or may have on the organisation. The recommendations have thus been made to address the challenges facing SMEs with regard to strategic planning, strategic performance measurement, capital budgeting and project risk evaluation.
- Full Text:
- Date Issued: 2013
Strategic planning as a tool for investment decision-making for SMEs in Nelson Mandela Metropole
- Authors: Kikine, Bereng Nimrode
- Date: 2013
- Subjects: Small business -- Management , Strategic planning
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6465 , vital:21094
- Description: All around the world, SMEs are perceived as the engine room of economic growth, job creation and poverty alleviation, due to their flexibility and quick adaptability to change. It is believed that, for developing countries to address their social and economic challenges, it would be beneficial if they leverage the potential that the SME sector potentially possess. However, despite the government focus on supporting and encouraging the establishment of SMEs through the small business development programmes in order to address these social challenges, SME sector has experienced a high degree of business mortality, which impacts negatively on the ability to create sustainable employment opportunities in the long term. This view is supported by the work of (Ligthelm and Cant 2003). According to the global economic monitor (GEM), the small business mortality in South Africa is among the highest in the world. It is said that that most newly established SMEs will not survive beyond 48 months Von Broembsen, as cited in Olawale and Garwe (2010: 730). One of the reasons that lead to the high failure rate of SMEs is the lack of strategic planning and the poor allocation of resources. The literature review suggests that SMEs that embark on strategic planning are the ones that are most likely to experience sales growth, personnel growth and asset value growth, as opposed those that do not do any strategic planning at all. The primary objective of this research was to establish how a strategic planning process can be used as an investment decision-making tool for manufacturing SMEs in the Nelson Mandela Metropole. In order to address this research problem, the following sub-problems had to be solved: What strategic planning processes do current SME managers use?; What strategic performance measurement systems do SME owner-managers currently use?; What capital budgeting techniques are currently being used by SME’s in the region?; How do SME owner-managers evaluate the risk of the projects at hand?. The research design was methodological triangulation in nature, that is, using both qualitative and quantitative methodologies, though a quantitative paradigm was more dominant that the qualitative paradigm. A questionnaire was designed as a primary source of data collection from a selected sample group. The empirical study revealed that there is some level of strategic planning amongst SMEs, however, it is mostly informal and unstructured. It also emerged that strategic planning can be used as more than just a performance measurement tool, it can contribute more effectively to strategic alignment, organisational learning and diffusion of knowledge throughout the organisation. The empirical study also suggests that SMEs understand that capital budgeting is critical for the success of the organisations. However, very few SMEs have a formal capital budgeting process. It also became evident that most SMEs are still relying on the traditional capital budgeting techniques; that is, ‘gut feel’ and the payback methods of evaluating projects. The empirical study suggests that the largest group of SMEs rely on break-even analysis and scenario planning as the major indicators of the impact the projects will or may have on the organisation. The recommendations have thus been made to address the challenges facing SMEs with regard to strategic planning, strategic performance measurement, capital budgeting and project risk evaluation.
- Full Text:
- Date Issued: 2013
- Authors: Kikine, Bereng Nimrode
- Date: 2013
- Subjects: Small business -- Management , Strategic planning
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6465 , vital:21094
- Description: All around the world, SMEs are perceived as the engine room of economic growth, job creation and poverty alleviation, due to their flexibility and quick adaptability to change. It is believed that, for developing countries to address their social and economic challenges, it would be beneficial if they leverage the potential that the SME sector potentially possess. However, despite the government focus on supporting and encouraging the establishment of SMEs through the small business development programmes in order to address these social challenges, SME sector has experienced a high degree of business mortality, which impacts negatively on the ability to create sustainable employment opportunities in the long term. This view is supported by the work of (Ligthelm and Cant 2003). According to the global economic monitor (GEM), the small business mortality in South Africa is among the highest in the world. It is said that that most newly established SMEs will not survive beyond 48 months Von Broembsen, as cited in Olawale and Garwe (2010: 730). One of the reasons that lead to the high failure rate of SMEs is the lack of strategic planning and the poor allocation of resources. The literature review suggests that SMEs that embark on strategic planning are the ones that are most likely to experience sales growth, personnel growth and asset value growth, as opposed those that do not do any strategic planning at all. The primary objective of this research was to establish how a strategic planning process can be used as an investment decision-making tool for manufacturing SMEs in the Nelson Mandela Metropole. In order to address this research problem, the following sub-problems had to be solved: What strategic planning processes do current SME managers use?; What strategic performance measurement systems do SME owner-managers currently use?; What capital budgeting techniques are currently being used by SME’s in the region?; How do SME owner-managers evaluate the risk of the projects at hand?. The research design was methodological triangulation in nature, that is, using both qualitative and quantitative methodologies, though a quantitative paradigm was more dominant that the qualitative paradigm. A questionnaire was designed as a primary source of data collection from a selected sample group. The empirical study revealed that there is some level of strategic planning amongst SMEs, however, it is mostly informal and unstructured. It also emerged that strategic planning can be used as more than just a performance measurement tool, it can contribute more effectively to strategic alignment, organisational learning and diffusion of knowledge throughout the organisation. The empirical study also suggests that SMEs understand that capital budgeting is critical for the success of the organisations. However, very few SMEs have a formal capital budgeting process. It also became evident that most SMEs are still relying on the traditional capital budgeting techniques; that is, ‘gut feel’ and the payback methods of evaluating projects. The empirical study suggests that the largest group of SMEs rely on break-even analysis and scenario planning as the major indicators of the impact the projects will or may have on the organisation. The recommendations have thus been made to address the challenges facing SMEs with regard to strategic planning, strategic performance measurement, capital budgeting and project risk evaluation.
- Full Text:
- Date Issued: 2013
Dual phototransformation of the pollutants methyl orange and Cr (VI) using phthalocyanine-cobalt ferrite based magnetic nanocomposites
- Mapukata, Sivuyisiwe, Osifeko, Olawale L, Nyokong, Tebello
- Authors: Mapukata, Sivuyisiwe , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187059 , vital:44561 , xlink:href="https://doi.org/10.1016/j.heliyon.2019.e01509"
- Description: Bifunctional nanocomposites based on zinc phthalocyanines and glutathione capped CoFe2O4 magnetic nanoparticles (GSH-CoFe2O4 MNPs) are applied in a binary system wherein simultaneous photooxidation of methyl orange (MO) and photoreduction of Cr (VI) are conducted. The photoactivity of two zinc Pcs with different functional moieties are compared based on their interactions with GSH-CoFe2O4 MNPs. Conjugation of the Pcs to the GSH-CoFe2O4 MNPs not only enhanced their singlet oxygen production but also their photocatalytic activity in both photooxidation and photoreduction experiments. Using electron paramagnetic resonance (EPR) spectroscopy, the Pc-MNP conjugates reported herein were found to exhibit superparamagnetic behaviour, giving the advantage of easy separation using an external magnetic field post application, an attractive attribute for heterogeneous catalysis. The catalysts reported herein are therefore good candidates as catalysts for real life water purification analyses as they facilitate the treatment of both organic and inorganic water pollutants.
- Full Text:
- Date Issued: 2019
- Authors: Mapukata, Sivuyisiwe , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187059 , vital:44561 , xlink:href="https://doi.org/10.1016/j.heliyon.2019.e01509"
- Description: Bifunctional nanocomposites based on zinc phthalocyanines and glutathione capped CoFe2O4 magnetic nanoparticles (GSH-CoFe2O4 MNPs) are applied in a binary system wherein simultaneous photooxidation of methyl orange (MO) and photoreduction of Cr (VI) are conducted. The photoactivity of two zinc Pcs with different functional moieties are compared based on their interactions with GSH-CoFe2O4 MNPs. Conjugation of the Pcs to the GSH-CoFe2O4 MNPs not only enhanced their singlet oxygen production but also their photocatalytic activity in both photooxidation and photoreduction experiments. Using electron paramagnetic resonance (EPR) spectroscopy, the Pc-MNP conjugates reported herein were found to exhibit superparamagnetic behaviour, giving the advantage of easy separation using an external magnetic field post application, an attractive attribute for heterogeneous catalysis. The catalysts reported herein are therefore good candidates as catalysts for real life water purification analyses as they facilitate the treatment of both organic and inorganic water pollutants.
- Full Text:
- Date Issued: 2019
The success factors of SMME's in New Brighton, Port Elizabeth
- Authors: Ngcwangu, Sivuyo
- Date: 2015
- Subjects: Small business -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6369 , vital:21079
- Description: The important role played by small, medium and micro enterprises (SMMEs) in economic development has long been recognised by government at various levels in South Africa. The passing of the National Small Business Act, 1996 (Act 102 of 1996), and more significantly its Amendment Act of 2004 (Act 29 of 2004) which called into existence the Small Enterprise Development Agency (SEDA), as well as a range of strategies headed by the current Integrated Strategy on the Promotion of Entrepreneurship and Small Enterprises of 2005 bear testimony to a commitment on the part of the nation to small enterprise growth. There is vast research pertaining challenges facing small medium and micro enterprises (SMMEs) as well as factors that have a positive impact on the growth and success of these enterprises. This primary objective of this study was to identify successful SMMEs in the New Brighton Township, Port Elizabeth and investigate factors that have enabled them to maintain their stability over the years. Also, this study will investigated causes of SMME failure with the aim of providing possible solutions to these challenges. After a comprehensive literature review on SMMEs, the following variables were identified as possibly having an influence on the growth and profitability of small enterprises. These are: Entrepreneurial orientation; Customer focus; Human resources; Record keeping; Access to funding; External support; Training and education; Access to markets. These variables were used to construct research hypotheses and a conceptual model which could be used to address challenges faced by SMMEs.
- Full Text:
- Date Issued: 2015
- Authors: Ngcwangu, Sivuyo
- Date: 2015
- Subjects: Small business -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6369 , vital:21079
- Description: The important role played by small, medium and micro enterprises (SMMEs) in economic development has long been recognised by government at various levels in South Africa. The passing of the National Small Business Act, 1996 (Act 102 of 1996), and more significantly its Amendment Act of 2004 (Act 29 of 2004) which called into existence the Small Enterprise Development Agency (SEDA), as well as a range of strategies headed by the current Integrated Strategy on the Promotion of Entrepreneurship and Small Enterprises of 2005 bear testimony to a commitment on the part of the nation to small enterprise growth. There is vast research pertaining challenges facing small medium and micro enterprises (SMMEs) as well as factors that have a positive impact on the growth and success of these enterprises. This primary objective of this study was to identify successful SMMEs in the New Brighton Township, Port Elizabeth and investigate factors that have enabled them to maintain their stability over the years. Also, this study will investigated causes of SMME failure with the aim of providing possible solutions to these challenges. After a comprehensive literature review on SMMEs, the following variables were identified as possibly having an influence on the growth and profitability of small enterprises. These are: Entrepreneurial orientation; Customer focus; Human resources; Record keeping; Access to funding; External support; Training and education; Access to markets. These variables were used to construct research hypotheses and a conceptual model which could be used to address challenges faced by SMMEs.
- Full Text:
- Date Issued: 2015
The influence of contemporary leadership styles on the job satisfaction and organisational commitment of SME employees
- Authors: Kupangwa, Welcome
- Date: 2015
- Subjects: Leadership , Job satisfaction , Organizational commitment , Business enterprises -- Employees
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:9013 , http://hdl.handle.net/10948/d1018508
- Description: Small and medium-sized enterprises (SMEs) have the potential to enhance economic growth and innovation, create jobs, assist large businesses in the distribution of goods and services, and stimulate competition in the economy. However, SMEs face several challenges that influence their longevity, growth, and success. Poor leadership has been highlighted as influencing the job satisfaction and organisational commitment levels of employees, ultimately contributing to employee turnover and SME failure. This study mentions the dishonest, selfish and corrupt nature of modern leadership and identifies a gap in the literature regarding the practice of leadership, especially among South African SMEs. Against this background, the primary objective of this study was to assess the levels of several contemporary leadership styles displayed by SME owners, namely Servant, Authentic, Ethical and Participative leadership, and to investigate their influence on the Job satisfaction and Organisational commitment levels of employees working in SMEs in the Eastern Cape. A quantitative research paradigm was adopted and a sample was drawn from employees working in SMEs in the Eastern Cape Province. The selection of the sample was done using judgement and convenience sampling. A cross-sectional survey using a structured questionnaire was undertaken, and a total of 236 usable questionnaires were returned on which to undertake the statistical analysis. In order to assess the validity of the dependent variables, namely Job satisfaction and Organisational commitment, tests for uni-dimensionality (using factor analysis) were undertaken. An exploratory factor analysis (EFA) was undertaken on the independent variables and four factors were extracted, which corresponded with the theoretical dimensions of Relational leadership, Participative leadership, Servant leadership and Ethical leadership. The items intended to measure Authentic leadership did not load as expected, but a factor named Relational leadership emerged as a result of several items measuring Ethical and Servant leadership loading together. All the independent and dependent variables returned Cronbach’s alpha coefficients of greater than 0.7. As such, sufficient evidence of validity and reliability for the scales measuring the dependent and the independent variables was provided. The data collected was also subjected to several statistical analyses. These included descriptive statistics, Pearson’s product moment correlations, multiple regression analyses, and analysis of variance (ANOVA). The majority of respondents agreed that they experienced Job satisfaction in the SMEs in which they were employed and that they were committed to these businesses. Relational leadership returned the highest mean score while the lowest score was returned for Participative leadership. The majority of respondents also agreed that the SME owners for whom they worked displayed the leadership styles under investigation. All the independent variables were significantly and positively correlated with the dependent variables, Job satisfaction and Organisational commitment. In addition, significant positive correlations were reported between all the independent variables. The multiple regression analyses revealed that three of the four leadership styles investigated in this study had a significant positive influence on both the Job satisfaction and Organisational commitment levels of employees working in the SMEs. These leadership styles were Servant, Relational, and Ethical leadership. In addition, the results of this study showed that Job satisfaction mediates the relationship between Servant, Relational and Ethical leadership, and the Organisational commitment displayed by employees working in SMEs, but does not mediate the relationship between Participative leadership and Organisational commitment. The findings also showed that the demographic variables investigated in this study had no influence on how SME employees perceived the Servant and Relational leadership behaviours of SME owners. However, the results showed that female respondents perceived SME owners as displaying a Participative leadership style more so than male employees did. The findings also revealed that employees with a post-matric qualification perceived that SME owners displayed higher levels of Participative leadership than those without a post-matric qualification. In addition, the ANOVA revealed that White respondents perceived that SME owners exhibited more ethical behaviours than Black respondents did. Given the findings of this study, several recommendations were put forward to enhance the levels of Servant, Relational and Ethical leadership among SME owners, and to ultimately enhance the levels of Job satisfaction and Organisational commitment experienced by their employees. As such SME owners were provided with practical recommendations on how to attract and retain employees by adopting appropriate leadership behaviours. Employees play a vital role in achieving the goals and vision of a business. Satisfied and committed employees put more effort into ensuring the goals and vision of the business are achieved, contributing to business success and ultimately the economy as a whole.
- Full Text:
- Date Issued: 2015
- Authors: Kupangwa, Welcome
- Date: 2015
- Subjects: Leadership , Job satisfaction , Organizational commitment , Business enterprises -- Employees
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:9013 , http://hdl.handle.net/10948/d1018508
- Description: Small and medium-sized enterprises (SMEs) have the potential to enhance economic growth and innovation, create jobs, assist large businesses in the distribution of goods and services, and stimulate competition in the economy. However, SMEs face several challenges that influence their longevity, growth, and success. Poor leadership has been highlighted as influencing the job satisfaction and organisational commitment levels of employees, ultimately contributing to employee turnover and SME failure. This study mentions the dishonest, selfish and corrupt nature of modern leadership and identifies a gap in the literature regarding the practice of leadership, especially among South African SMEs. Against this background, the primary objective of this study was to assess the levels of several contemporary leadership styles displayed by SME owners, namely Servant, Authentic, Ethical and Participative leadership, and to investigate their influence on the Job satisfaction and Organisational commitment levels of employees working in SMEs in the Eastern Cape. A quantitative research paradigm was adopted and a sample was drawn from employees working in SMEs in the Eastern Cape Province. The selection of the sample was done using judgement and convenience sampling. A cross-sectional survey using a structured questionnaire was undertaken, and a total of 236 usable questionnaires were returned on which to undertake the statistical analysis. In order to assess the validity of the dependent variables, namely Job satisfaction and Organisational commitment, tests for uni-dimensionality (using factor analysis) were undertaken. An exploratory factor analysis (EFA) was undertaken on the independent variables and four factors were extracted, which corresponded with the theoretical dimensions of Relational leadership, Participative leadership, Servant leadership and Ethical leadership. The items intended to measure Authentic leadership did not load as expected, but a factor named Relational leadership emerged as a result of several items measuring Ethical and Servant leadership loading together. All the independent and dependent variables returned Cronbach’s alpha coefficients of greater than 0.7. As such, sufficient evidence of validity and reliability for the scales measuring the dependent and the independent variables was provided. The data collected was also subjected to several statistical analyses. These included descriptive statistics, Pearson’s product moment correlations, multiple regression analyses, and analysis of variance (ANOVA). The majority of respondents agreed that they experienced Job satisfaction in the SMEs in which they were employed and that they were committed to these businesses. Relational leadership returned the highest mean score while the lowest score was returned for Participative leadership. The majority of respondents also agreed that the SME owners for whom they worked displayed the leadership styles under investigation. All the independent variables were significantly and positively correlated with the dependent variables, Job satisfaction and Organisational commitment. In addition, significant positive correlations were reported between all the independent variables. The multiple regression analyses revealed that three of the four leadership styles investigated in this study had a significant positive influence on both the Job satisfaction and Organisational commitment levels of employees working in the SMEs. These leadership styles were Servant, Relational, and Ethical leadership. In addition, the results of this study showed that Job satisfaction mediates the relationship between Servant, Relational and Ethical leadership, and the Organisational commitment displayed by employees working in SMEs, but does not mediate the relationship between Participative leadership and Organisational commitment. The findings also showed that the demographic variables investigated in this study had no influence on how SME employees perceived the Servant and Relational leadership behaviours of SME owners. However, the results showed that female respondents perceived SME owners as displaying a Participative leadership style more so than male employees did. The findings also revealed that employees with a post-matric qualification perceived that SME owners displayed higher levels of Participative leadership than those without a post-matric qualification. In addition, the ANOVA revealed that White respondents perceived that SME owners exhibited more ethical behaviours than Black respondents did. Given the findings of this study, several recommendations were put forward to enhance the levels of Servant, Relational and Ethical leadership among SME owners, and to ultimately enhance the levels of Job satisfaction and Organisational commitment experienced by their employees. As such SME owners were provided with practical recommendations on how to attract and retain employees by adopting appropriate leadership behaviours. Employees play a vital role in achieving the goals and vision of a business. Satisfied and committed employees put more effort into ensuring the goals and vision of the business are achieved, contributing to business success and ultimately the economy as a whole.
- Full Text:
- Date Issued: 2015
Physicochemical and antimicrobial photodynamic chemotherapy of unsymmetrical indium phthalocyanines alone or in the presence of magnetic nanoparticles
- Osifeko, Olawale L, Uddin, Imran, Mashazi, Philani N, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Uddin, Imran , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189121 , vital:44818 , xlink:href="https://doi.org/10.1039/C5NJ01922B"
- Description: An AB3 type photosensitiser, consisting of 4-pyridylsulfanyl units (denoted as B3) and one aminophenoxy (denoted as A) group (complex 3) was synthesized. Complex 3 was then quaternized to form complex 4. The aminophenoxy substituent of complex 3 was used for the formation of the amide linkage with the carboxylic functionalised magnetic nanoparticles. Complexes 3 and 4 and their conjugates with magnetic nanoparticles were then used for photodynamic antimicrobial chemotherapy on E. coli. The cationic photosensitiser 4 showed a high efficiency for photodynamic antimicrobial chemotherapy at a very low concentration compared to its conjugate on E. coli.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale L , Uddin, Imran , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189121 , vital:44818 , xlink:href="https://doi.org/10.1039/C5NJ01922B"
- Description: An AB3 type photosensitiser, consisting of 4-pyridylsulfanyl units (denoted as B3) and one aminophenoxy (denoted as A) group (complex 3) was synthesized. Complex 3 was then quaternized to form complex 4. The aminophenoxy substituent of complex 3 was used for the formation of the amide linkage with the carboxylic functionalised magnetic nanoparticles. Complexes 3 and 4 and their conjugates with magnetic nanoparticles were then used for photodynamic antimicrobial chemotherapy on E. coli. The cationic photosensitiser 4 showed a high efficiency for photodynamic antimicrobial chemotherapy at a very low concentration compared to its conjugate on E. coli.
- Full Text:
- Date Issued: 2016