Detecting change in local ecological knowledge: An application of an index of taxonomic distinctness to an ethnoichthyological classification in the Solomon Islands
- Authors: Aswani, Shankar , Ferse, Sebastien C , Stäbler, Moritz , Chong-Montenegro, Carolina
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406521 , vital:70282 , xlink:href="https://doi.org/10.1016/j.ecolind.2020.106865"
- Description: The global accelerating loss of biodiversity is having immediate repercussions for ecosystems and human wellbeing, particularly in areas where people depend intimately on their natural environment for their livelihoods. Dovetailing this loss is the demise of local/traditional knowledge systems resulting from factors such as changing lifestyle and the transformation of local belief systems. While the importance of local ecological knowledge (LEK) for documentation of biodiversity and environmental change and development of management responses is well established, quantitative tools to analyze and systematically compare LEK are scarce. In this research, we analyze the complexity of local ecological knowledge used by respondents to classify locally-recognized marine species. We do so by applying a modified index of taxonomic distinctness to an ethnoichthyological classification in coastal communities in the Solomon Islands. In addition, we assess simple taxonomic diversity (richness in locally-recognized species names) by comparing taxonomies collected in 1992–1995 and 2014–2015. Results indicate that both endogenous (gender, age) and exogenous (proximity to market) factors have discernible effects on folk taxonomic knowledge in the region, with younger respondents and communities closer to a regional market center displaying a significantly lower richness of local species names. Folk taxonomic distinctness was significantly reduced closer to the regional market. The modified index of taxonomic distinctness applied in this research provides a useful tool to explore facets of local ecological knowledge in addition to simple richness of terms, and to compare across different regions and cultural backgrounds. Understanding changes in LEK is important because such knowledge enables communities who are highly dependent on living natural resources to harvest and manage resources more efficiently and also to detect and react to environmental change.
- Full Text:
- Date Issued: 2020
Detecting Similarity in Multi-procedure Student Programs Using only Static Code Structure
- Authors: Bradshaw, Karen L , Chindeka, Vongai
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/440260 , vital:73761 , ISBN 9783030356286 , https://doi.org/10.1007/978-3-030-35629-3_14
- Description: Plagiarism is prevalent in most undergraduate programming courses, including those where more advanced programming is taught. Typical strategies used to avoid detection include changing variable names and adding empty spaces or comments to the code. Although these changes affect the visual components of the source code, the underlying structure of the code remains the same. This similarity in structure can indicate the presence of plagiarism. A system has been developed to detect the similarity in the structure of student programs. The detection system works in two phases: The first phase parses the source code and creates a syntax tree, representing the syntactical structure of each of the programs, while the second takes as inputs two program syntax trees and applies various comparison algorithms to detect their similarity. The outcome of the comparison allows the system to report a result from one of four similarity categories: identical structure, isomorphic structure, containing many structural similarities, and containing few structural similarities. Empirical tests on small sample programs show that the prototype implementation is effective in detecting plagiarism in source code, although in some cases manual checking is needed to confirm the presence of plagiarism.
- Full Text:
- Date Issued: 2020
Detonation nanodiamonds-phthalocyanine photosensitizers with enhanced photophysicochemical properties and effective photoantibacterial activity
- Authors: Openda, Yolande I , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186012 , vital:44455 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102072"
- Description: The nanophotosensitizers based on acetophenoxy tetrasubstituted metallophthalocyanines (MPc) and detonation nanodiamonds (DNDs) were successfully formed and their photophysicochemical properties were determined. The zinc(II)Pc and indium(III)Pc complexes along with their nanoconjugates were found to have high singlet oxygen quantum yields (0.72 − 0.84) associated with the heavy central metal effect. The ability of the functional groups present on the DNDs to bind to the bacteria cell and the improved solubility of the nanoconjugates due to DNDs resulted in effective photodynamic antimicrobial therapy (PACT) activity against S. aureus planktonic cells, with the highest log reduction of 9.72 ± 0.02 for the conjugate of InPc conjugate with DNDs after 30 min irradiation. PACT studies were investigated at a dose of 10 μg/mL for each sample. The results suggest that the readily synthesized nanoconjugates can be used as appropriate PACT agents.
- Full Text:
- Date Issued: 2020
Development of phthalocyanine functionalised TiO 2 and ZnO nanofibers for photodegradation of methyl orange
- Authors: Mapukata, Sivuyisiwe , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186323 , vital:44485 , xlink:href="https://doi.org/10.1039/D0NJ03326J"
- Description: The photocatalytic activity of TiO2 and ZnO based catalysts, which is based on their ability to generate electron–hole pairs upon photoillumination is limited due to their wide band gaps and lack of efficient retrievability post-application. This work reports on the fabrication, characterisation and comparison of electrospun TiO2 and ZnO nanofibers when bare vs when functionalised with a phthalocyanine. The generated photocatalysts are attractive because they absorb visible light and are easily retrievable and hence reusable. With the Pc anchored onto their surfaces, the anatase TiO2 nanofibers and the wurzite ZnO nanofibers possessed singlet oxygen quantum yields of 0.22 and 0.16 in water, respectively. Evaluation of the photocatalytic efficiencies of the nanofibers was conducted by studying the photodegradation of methyl orange. The Pc decorated nanofibers were found to be more effective photocatalysts than the bare ones with the phthalocyanine TiO2 nanofibers being the best. The degradation kinetics were found to follow pseudo first order kinetics and obeyed the Langmuir Hinshelwood model. The nanocatalysts reported herein are therefore feasible candidates for real-life water purification applications.
- Full Text:
- Date Issued: 2020
Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441919 , vital:73935 , https://doi.org/10.1016/j.fooweb.2020.e00152
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
Direct nonlinear optical absorption measurements of asymmetrical zinc (II) phthalocyanine when covalently linked to semiconductor quantum dots
- Authors: Mgidlana, Sithi , Sen, Pinar , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186056 , vital:44459 , xlink:href="https://doi.org/10.1016/j.molstruc.2020.128729"
- Description: We report on nonlinear optical properties of tris[(4-tert-butyl)-2-thio (phenyl)acetic acid (1) and tris(dimethyl-5-(3,4-phenoxy) isophthalate (2) phthalocyaninato zinc (II) complexes. The synthesized complexes were covalently conjugated to glutathione-capped CdTe/ZnSe/ZnO quantum dots. We observed an increase in triplet quantum yield with corresponding decrease in fluorescence quantum yield of conjugates compared to Pc complexes alone. Z-scan technique was employed to experimentally test the nonlinear optical response of complexes and nanoconjugates in solution at laser excitation wavelength of 532 nm with 7 ns pulse. Nonlinear absorption coefficient, third-order optical susceptibility and optical limiting threshold of the materials were obtained from the Z-scan data. The nonlinear absorption parameters improved in the presence of CdTe/ZnSe/ZnO, with 1 and 1-CdTe/ZnSe/ZnO, giving the best results due to the presence of electron donating substituents.
- Full Text:
- Date Issued: 2020
Double-and quintuple-decker phthalocyaninato chelates as optical limiters in solution and thin film
- Authors: Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186733 , vital:44529 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107836"
- Description: The rare-earth quintuple-decker phthalocyaninato chelates (3a and 3b) were synthesized from their parent rare-earth double-decker phthalocyaninato precursors (2b and 2a). After extensive structural elucidation, these complexes were subjected to various spectroscopic techniques to investigate their electronic behavior. It was found that complexes 3a and 3b existed as the oxidized forms. When investigating the optical limiting properties, all these complexes were found to exhibit reverse saturable absorption, with complex 2a showing a more enhanced open-aperture Z-Scan signature than complex 2b. Interestingly, complexes 3a and 3b (in solution) exhibited better open-aperture Z-Scan signatures than their parent rare-earth double-decker phthalocyaninato precursors (2b and 2a). However, thin films fabricated from these complexes did not show an improvement in the optical limiting properties when compared to 2a, 3a, 3b except for that which was prepared from 2b. This study shows the importance of extensive π-electron system in phthalocyaninato complexes for optical limiting applications.
- Full Text:
- Date Issued: 2020
Eco-schools as education for sustainable development in rural South Africa
- Authors: Rosenberg, Eureta
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436854 , vital:73310 , ISBN 978-3-030-46820-0 , https://doi.org/10.1007/978-3-030-46820-0_16
- Description: This chapter takes the reader into the context of rural South Africa with a sketch of developmental and educational chal-lenges from the point of view of a young person born here. It goes on to ask whether Eco-Schools has a role in this chal-lenging context, as a vehicle for or form of Education for Sus-tainable Development (ESD). Past Eco-Schools evaluations are reviewed against current educational needs and livelihood opportunities. The findings suggest that Eco-Schools gives teachers greater environmental awareness and motivates pedagogical practices such as active learning in relation to lo-cally relevant issues. Learners develop environmental com-mitment and a sense of agency, and may become more com-mitted to academic learning – all of which is necessary to pre-pare them for thriving in and also improving their socio-ecological contexts. Eco-Schools further supports schools sys-temically through meaningful partnerships with external agen-cies. The conclusion is that attempts should be made to scale up and scale out this impact. In the process, key features of the programme should be preserved. These include a focus on sustainable solutions.
- Full Text:
- Date Issued: 2020
Editorial for Special Issue: Education for Sustainability in a Time of Crises
- Authors: Rosenberg, Eureta
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370533 , vital:66352 , xlink:href="10.4314/sajee.v36i1.1"
- Description: There is an old and still popular saying that a crisis is an opportunity for change. The Chinese symbol for crisis is translated in Wikipedia as “danger at a point of juncture”. In the year 2020, first China and then the rest of humanity have been presented with a monumental crisis: a new and lethal virus that spread fast and far, causing actions and reactions, with dramatic consequences for social and economic life around the globe. Rebecca Solnit wrote of another crisis in her book Hope in the Dark: The Untold Story of People Power. In Grounds for Hope, a foreword to the 2015 edition (p.2), she stated: “This is an extraordinary time full of vital, transformative movements, that could not be foreseen. It’s also a nightmarish time. Full engagement requires the ability to perceive both.”.
- Full Text:
- Date Issued: 2020
Education in times of COVID-19: Looking for silver linings in the Southern Africa’s educational responses
- Authors: Mukute, Mutizwa , Francis, Buhle , Burt, Jane C , De Souza, Ben
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389799 , vital:68484 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/198219"
- Description: Coronavirus Disease 2019 (COVID-19) has disrupted socio-economic activities, including formal and non-formal education, across the world at lightning speed. By mid-April 2020, it had interrupted the formal education of nearly 1.6 billion students in 192 countries. COVID-19’s disruption of education in Africa, and especially in southern Africa, has been severe for several reasons. However, educational responses to COVID-19 suggest that it has stimulated the appetite for developing educational innovations – silver linings to the COVID-19 cloud. This paper is based on interviews conducted with 56 parents, students and educators involved in formal and non-formal education in Botswana, Malawi, Namibia, South Africa, Zambia and Zimbabwe. We identified the main educational challenges in these countries as being concerned with adapting to: (i) online education and learning, (ii) continuity of education from home, and (iii) community-based learning in small groups. The silver linings that we identified are: (i) putting greater emphasis on finding context-specific solutions to education and health problems (improvisation), which is important for educational relevance and reveals the value of local actors, (ii) making linkages between social and ecological systems clearer, which is making the value of education for sustainable development (ESD) in this century more explicit, and (iii) revealing structural inequality and justice issues in education, which draws attention to the need for urgently addressing them as part of transformative change in education and sustainable development.
- Full Text:
- Date Issued: 2020
Education versus screening
- Authors: Kong, Camillia , Efrem, Mehret , Campbell, Megan
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302461 , vital:58198 , xlink:href="http:// 10.1136/medethics-2019-105396"
- Description: Informed consent procedures for participation in psychiatric genomics research among individuals with mental disorder and intellectual disability can often be unclear, particularly because the underlying ethos guiding consent tools reflects a core ethical tension between safeguarding and inclusion. This tension reflects important debates around the function of consent tools, as well as the contested legitimacy of decision-making capacity thresholds to screen potentially vulnerable participants. Drawing on human rights, person-centred psychiatry and supported decisionmaking, this paper problematises the use of consent procedures as screening tools in psychiatric genomics studies, particularly as increasing normative emphasis has shifted towards the empowerment and participation of those with mental disorder and intellectual disabilities. We expound on core aspects of supported decisionmaking, such as relational autonomy and hermeneutic competence, to orient consent procedures towards a more educative, participatory framework that is better aligned with developments in disability studies. The paper concludes with an acknowledgement of the pragmatic and substantive challenges in adopting this framework in psychiatric genomics studies if this participatory ethos towards persons with mental disorder and intellectual disability is to be fully realised.
- Full Text:
- Date Issued: 2020
Effectiveness of private land conservation areas in maintaining natural land cover and biodiversity intactness
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Ament, Judith M , Clements, Hayley S
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415852 , vital:71294 , xlink:href="https://doi.org/10.1016/j.gecco.2020.e00935"
- Description: Private land conservation areas (PLCAs) are increasingly looked to for meeting the deficit left by state-owned protected areas in reaching global conservation targets. However, despite the increasing extent and recognition of PLCAs as a complementary conservation strategy, little research has been done to quantify their effectiveness; a critical consideration if they are to be counted towards international biodiversity conservation targets. The long history of PLCAs in South Africa provides an interesting case study to address this knowledge gap. Here, we quantified the effectiveness of South African PLCAs by comparing losses in natural land cover and biodiversity intactness within PLCAs with different levels of protection to that of unprotected control points. Points within PLCAs were matched with unprotected control points to test the prediction that if PLCAs offer effective protection, losses in natural land cover and biodiversity intactness would be significantly lower within their boundaries in comparison to unprotected controls exposed to similar conditions. Consequences of natural land cover loss on biodiversity intactness were thus assessed, thus advancing standard approaches for quantifying effectiveness.
- Full Text:
- Date Issued: 2020
Electrodeposited Benzothiazole Phthalocyanines for Corrosion Inhibition of Aluminium in Acidic Medium
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186112 , vital:44464 , xlink:href="https://doi.org/10.1155/2020/8892559"
- Description: Tetrakis[(benzo[d]thiazol-2-yl-thio) phthalocyaninato] gallium(III)chloride (1) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. The aim of this study was to compare the corrosion resistance of electrodeposited metallated phthalocyanines. Scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy (EIS), and polarization confirmed the aluminium corrosion inhibition potentials of complexes 1 and 2. EIS and polarization techniques showed that complex 2 performed better than complex 1, with values from EIS measurements of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution. The importance of electrodeposition in industries and a dearth of research on the use of electrodeposited metallated phthalocyanines necessitated this study, and results show that coatings formed by electrodeposition of 1 and 2 onto aluminium reduced its susceptibility to corrosion attack.
- Full Text:
- Date Issued: 2020
Electronic and nonlinear optical properties of 2-(((5-aminonaphthalen-1-yl) imino) methyl) phenol
- Authors: Ojo, Nathanael D , Krause, Rui W M , Obi-Egbedi, Nelson O
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193397 , vital:45328 , xlink:href="https://doi.org/10.1016/j.molliq.2020.114157"
- Description: In this study, solvent dependence of electronic and nonlinear optical properties of a new Schiff base, 2-(((5-aminonaphthalen-1-yl)imino)methyl) phenol (DANOHB), has been investigated. Electronic and optical properties of the Schiff base studied using Uv-visible absorption and fluorescence spectroscopic techniques in solution show that the Schiff base exhibits fluorescence with a quantum yield of 0.21 and a Stokes shift of 39 nm. Quantum chemical calculations were performed on the Schiff base at time-dependent density functional level of theory using Becke-3-Lee-Yang-Parr method with 6-311++G(d,p) basis set. Solvent dependence of the excited state energies (EE), energy gap (ΔE), first-order (β) and second-order (γ) hyperpolarizabilities were studied in gas, cyclohexane and ethanol. The medium perturbed the energy levels which implies that the reactivity, activity and stability of the system are solvent sensitive. The γ is more than thirty times higher than urea (standard NLO material) and this property is further enhanced in less polar medium. Small ΔE and large hyperpolarizabilities obtained for this system suggest its good potential in photonics and nonlinear optical devices.
- Full Text:
- Date Issued: 2020
Electronic and nonlinear optical properties of 3-(((2-substituted-4-nitrophenyl) imino) methyl) phenol
- Authors: Ojo, Nathanael D , Krause, Rui W M , Obi-Egbedi, Nelson O
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193408 , vital:45329 , xlink:href="https://doi.org/10.1016/j.comptc.2020.113050"
- Description: This work entails the study of electronic and nonlinear optical (NLO) properties of two synthesized Schiff bases namely 3-(((2-methyl-4-nitrophenyl)imino)methyl)phenol (MMP) and 3-(((2,4-dinitrophenyl)imino)methyl)phenol (DMP). Electronic absorption properties studied using UV–Visible spectrophotometry in ethanol reveal low-energy absorption indicating a low band gap. Time-dependent density functional calculations on their excited state properties with ωB97X-D/6-311++G(d,p) method show comparable transition energies and intensities with the experimental results. Energy gaps (ΔE) and NLO properties were evaluated from the frontier orbitals and hyperpolarizabilities (βtot and γ) in gas, cyclohexane and ethanol. Low ΔE obtained shows the potentials of the systems as organic semiconductor with remarkable band gap stabilization in ethanol. Higher βtot and γ than urea imply that the Schiff bases possess potentials for NLO applications. The solvatochromic shift in transition energies and perturbation of electronic properties reveal the solvent dependence of the electronic and optical properties of MMP and DMP due to solute-solvent interactions.
- Full Text:
- Date Issued: 2020
Encapsulation and physicochemical evaluation of efavirenz in liposomes
- Authors: Okafor, Nnamdi Ikemefuna , Nkanga, Christian I , Walker, Roderick B , Noundou, Xavier S , Krause, Rui W M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183414 , vital:43988 , xlink:href="https://doi.org/10.1007/s40005-019-00458-8"
- Description: Antiretroviral therapy remains the most efective means of managing the human immune defciency virus/acquired immune defciency syndrome (HIV/AIDS). Application of therapeutics has been hampered by factors including poor bioavailability of most anti-retroviral compounds (ARV), side efects and an alarming emergence of drug resistant strains of the virus. Recent developments and use of drug delivery systems (DDS) has shown potential for improving the pharmacological profle of ARV. Amongst these complex DDS, liposomes have been explored for delivery of ARV. In this study, we have aimed at exploring efcient encapsulation of efavirenz (EFV), a potent ARV using diferent mass ratios of crude soybean lecithin and cholesterol. The EFV-loaded liposomes (EFL) were prepared using thin flm hydration and evaluated for particle size, zeta potential (ZP), encapsulation efciency (EE%), morphology and drug release studies. Diferential scanning calorimetry (DSC), X-ray difraction (XRD), energy dispersity spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy were used for comprehensive physicochemical characterization of EFL. EFL exhibited high encapsulation (99%) in 1:1 crude lecithin to cholesterol mass ratio. The average particle size and Zeta Potential of EFL were found to be 411.10±7.40 nm and −53.5.3±0.06 mV, respectively. EFL showed a relatively controlled EFV release behaviour that was similar to the dissolution profle of un-encapsulated EFV. This suggests that EFL represents a promising vehicle for efective EFV delivery while providing the advantages of a nano-scaled delivery system
- Full Text:
- Date Issued: 2020
Enhanced Light-Driven Antimicrobial Activity of Cationic Poly (oxanorbornene) s by Phthalocyanine Incorporation into Polymer as Pendants
- Authors: Ahmetali, Erem , Sen, Pinar , Süer, N Ceren , Aksu, Burak , Nyokong, Tebello , Eren, Tarik , Sener, Kasim M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185976 , vital:44453 , xlink:href=" https://doi.org/10.1002/macp.202000386"
- Description: Amphiphilic poly(oxanorbornene)s are promising synthetic polymers that mimic the structural properties and antimicrobial functions of naturally occurring antimicrobial peptides. Here, poly(oxanorbornene)s bearing pendant zinc(II) phthalocyanine and triphenyl(ethyl) phosphonium functionalities are synthesized by ring-opening metathesis polymerization (ROMP). Fluorescence, singlet oxygen and triplet quantum yields of polymers are measured in dimethyl sulfoxide and aqueous medium. The singlet oxygen quantum yields of copolymers with the highest triphenyl and triethyl phosphonium content are found to be 0.29 and 0.41, respectively. Then, antimicrobial activities of polymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are investigated under both dark and light conditions. Synergistic effect of zinc(II) phthalocyanine and phosphonium-containing poly(oxanorbornene) is observed that the conjugate possessing the most triphenyl phosphonium side chains has the highest activity under light against both gram-positive and gram-negative bacterial strains after 80 min irradiation, reducing the survival of E. coli or S. aureus by 99.9999%. Hemolytic concentrations of the copolymers are found between 8 and 512 µg mL−1. Scanning electron microscopy (SEM) proves that the bacteria membrane deforms after contacting with the biocidal polymer.
- Full Text:
- Date Issued: 2020
Enhanced photodynamic antimicrobial activity of surface modified SiNPs doped with zinc (II) phthalocyanines: The effect of antimicrobial ampicillin and extra charges from a sultone
- Authors: Magadla, Aviwe , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186034 , vital:44457 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.101996"
- Description: 1-(2-Methoxyethyl) piperidine sustituted Zn phthalocyanine complex (2) is synthesised and quartenised (3). These complexes are loaded into silica nanoparticles (SiNPs) that are futher surface modified with ampicillin and 1.3-propanesultone. The photophysical and photochemical properties of the complexes and their doped conjugates were investigated in dimethylsulfoxide. The cationic complex (3) is used for photodynamic antimicrobial activity. Log reduction values of above 9 are obtained towards the photoiactivation of Staphyloccocus aureus.
- Full Text:
- Date Issued: 2020
Enhancement of photodynamic antimicrobialtherapy through the use of cationic indium porphyrin conjugated to Ag/CuFe2O4 nanoparticles
- Authors: Makola, Collen L , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186233 , vital:44475 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.101736"
- Description: Photodynamic antimicrobial chemotherapy (PACT) is being actively researched as a possible alternative for antimicrobial agents. This study focuses on the application of neutral indium 5-p-carboxyphenyl-10-15-20-(tri-4-pyridyl)porphyrin and cationic indium 5-p-carboxyphenyl-10-15-20-(tris-4-methylpyridyl)-porphyrin triiodide conjugated to 6-mercapo-1-hexanol functionalized Ag/CuFe2O4 magnetic nanoparticles for photo-inactivation of S. aureus bacteria. Comparative studies were done on quaternized and unquaternized indium porphyrin complexes conjugated to Ag/CuFe2O4, where log reduction of 9.27 was obtained for quaternized conjugate and 0.83 for unquaternized conjugate.
- Full Text:
- Date Issued: 2020
Environmental health promotion at a National Science Festival: An experiential-education based approach
- Authors: Duxbury, Theodore , Bradshaw, Karen L , Khamanga, Sandile , Tandlich, Roman , Srinivas, Sunitha
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440274 , vital:73762 , xlink:href="https://doi.org/10.1080/1533015X.2019.1567406"
- Description: To increase individual and communal environmental health awareness through an experiential-education project. A computer-based pre- and postintervention quiz; an educational poster; an interactive board game; and a take-home information leaflet were utilized for a school learners-centered health promotion exhibit at a National Science Festival in Grahamstown, South Africa. Out of all the participants, 55.7% were female, and 76.5% attended or had attended a government school. Participants showed significant improvement in their pre- and post educational intervention. The exhibit was effective in educating participants on environmental health, natural resources, and the impact environmental pollution has on their quality of life.
- Full Text:
- Date Issued: 2020