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The development, formulation and characterization of an optimized metronidazole loaded solid lipid nanoparticle formulation for ocular drug delivery
No full textThesis embargoed. To be released early 2026.Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 202
Is green space associated with reduced crime? A national-scale study from the Global South
Get PDFAssumptions about the link between green space and crime mitigation are informed by literature that overwhelmingly originates in the Global North. Little is known about the association between green spaces and crime in the Global South. We utilized 10 years of precinct-level crime statistics (n = 1152) over South Africa, a global crime hotspot, to test the hypothesis that green space is associated with reduced crime rates. We found that, after controlling for a number of socio-demographic confounders (unemployment, income, age, education, land use and population density), for every 1% increase in total green space there is a 1.2% (0.7 to 1.7%; 95% confidence interval) decrease in violent crime, and 1.3% (0.8 to 1.8%) decrease in property crime, with no effect on sexual crimes. However, the direction of the association changed for property crimes when exploring the effect of green space characteristics including tree cover and park accessibility. Property crimes increase by 0.4% (0.1 to 0.7%) with a percentage increase in tree cover, and by 0.9% (0.5 to 1.3%) with every kilometer increase in proximity to a public park. Further research, including experimental studies, is needed to better isolate causal mechanisms behind crime-green space associations, especially considering that green space may map to race and income inequality and that there may be more crime reporting in affluent areas. Nevertheless, our results provide a complementary contribution to the evidence from the Global North, highlighting the need for more nuanced definitions of green space and its characteristics when considering links to crime. When viewed in light of the broader suite of ecosystem services provided by green space, our results support urban greening as a major strategy towards achieving just and sustainable cities and towns
Understanding rural–urban transitions in the Global South through peri-urban turbulence
Get PDFMuch previous research has problematized the use of a binary urban–rural distinction to describe human settlement patterns in and around cities. Peri-urban zones, on the edge of urban settlements, are important both in the sheer magnitude of human population and in terms of being home to vulnerable populations with high rates of poverty. This Perspective presents a framework that conceptualizes rural–urban transition through the prism of shifts in natural, engineered and institutional infrastructure to explain the processes of rapid change and the dip in service provision often found in peri-urban areas in the Global South. We draw on examples related to the provision of water and sanitation to illustrate the theory and discuss its implications for future research on the peri-urban. A research agenda is set out that emphasizes the importance of studying early warning signs of service dips using systems theory concepts such as flickering and critical slowing down. Through such approaches, research can better predict and explain what we call peri-urban turbulence and inform the development of mitigation strategies to reduce the vulnerabilities that peri-urban residents too often face during periods of rural–urban transition
The contribution of wild palms to the livelihoods and diversification of rural households in southern Mozambique
Get PDFIn most low-income countries, rural households combine a range of economic activities to generate income, achieve food and nutritional security and fulfill other livelihood objectives, including: small-scale farming, fishing, hunting, livestock and timber production, and non-timber forest products gathering, as well as off-farm activities such as wage labour and informal trading. This work examines the role of diversification, including palm products income, on rural livelihoods in the Zitundo area, southern Mozambique. Seven livelihood strategies were identified, with every strategy combining cash income from several sources. Most households adopt a wage-based strategy to some degree, although this strategy shows low potential for reducing poverty in the area. Households adopting a palm-based strategy show between 23% and 60% lower poverty incidence than those adopting alternatives strategies. Yet, a palm-based livelihood strategy was adopted by only 11% of households. Traders of palm products earn approximately double the annual income and per capita income than non-traders. Village of residency and some household socio-economic and demographic characteristics correlate with a households' choice of livelihood strategy and palm income dependency. The adherence of many households to a less remunerative wage strategy indicates other factors also influence the choice of livelihood strategies. The study shows that future development plans and policy interventions to mitigate poverty in the area should go beyond the usual agricultural sector and recognize the role of non-timber forest products, especially palm products, for people's livelihoods and poverty alleviation
Synthesis and evaluation of pyrene grafted onto zinc oxide nanoparticles for the removal of organic contaminants from wastewater
Get PDFDrinking water scarcity is a global crisis even though water covers about three quarters of the earth. One of the major causes of this scarcity is water pollution, which is a result of human activities. This has been noticed and reported for a number of years but is still unsolved and intensifying. Hence, scientists are busy trying to find solutions to this global menace. In this study, zinc oxide nanoparticles were synthesised via co-precipitation, a cost reasonable method and functionalized by grafting a pyrene ligand on its surface in order to provide a scaffold to which many other functionalities can be adsorbed. By so doing, the efficiency and capacity of bare nanoparticles is improved. The synthesised pyrene ligand was successfully characterised with nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscope (FTIR). The adsorbent was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), FTIR, energy dispersive x-ray (EDX) and thermogravimetric analyzer (TGA). The choice of zinc oxide nanoparticles as preferred adsorbent was due to their exceptional properties including large surface area, thermal and chemical stabilities. These properties are the reason zinc oxide nanoparticles possess high adsorption efficiency and capacity. The results of characterization indicated a decreased particle size and improved thermal stabilities of the pyrene grafted zinc oxide nanoparticles compared to the zinc oxide nanoparticles, showing that this material can be employed even at higher temperatures. The average particle size of the bare nanoparticles decreased from 290 to 181 nm after functionalization. Thermal stability increased from 550oC in the bare nanoparticles to 650oC in the functionalized nanoparticles. Characteristic reflections of zinc oxide nanoparticles in the XRD analysis were maintained even after functionalization However, diffractogram roughness was noticed for the functionalized nanoparticles due to the introduction of the amorphous layer from the ligand. This novel material was employed for the removal of an herbicide, simazine as well as two dyes, methyl violet and brilliant green from aqueous solutions by batch adsorption experiments. The kinetics and isotherm studies of the different adsorption processes were carried out by using three of the commonly used kinetic and isotherm models (pseudo-first order, intraparticle diffusion and pseudo-second order) and (Langmuir, Temkin isotherms and Freundlich) respectively. From all batch adsorption experiments conducted for simazine removal, the adsorbent showed effectiveness and high adsorption capacity for the removal of simazine. The highest observed efficiency and capacity were 71.3 percent and 137 mg/g respectively at pH equals 2, time equals 60 minutes, adsorbent dose equals 20 mg and adsorbate conc equals 0. 281 mg/L. Kinetics study for the adsorption of simazine favoured pseudo-first order. However, Langmuir isotherm could also be applicable to understand the adsorption process. The material also showed reusability potential of up to three cycles for this contaminant indicating that this material can be re-used. In the case of the removal of methyl violet from aqueous solution, the adsorbent showed a reasonable adsorption maximum capacity (qmax) (31.5 mg/g) at contact time equals 360 min, adsorbent dose approximately equals 40 mg, temperature equals 20 plus 2oC and pH equals 6.5, when compared to other adsorbents previously reported for the removal of methyl violet (MV) in literature. Kinetics and isotherm studies indicated that the process for the removal of this pollutant with this pyrene grafted onto zinc oxide nanoparticles proceeded via pseudo-first order (R2 equals 0.931) and Langmuir isotherm models (R2 equals 0.980) respectively. These results indicated that this material could serve as alternate material to already established materials for the removal of recalcitrant organic pollutants from aqueous solutions. Moreover, the adsorbent also showed reusability potential for this contaminant. Similarly, the adsorbent showed high removal efficiency and capacity in all batch adsorption experiments for brilliant green (BG) adsorption. The highest adsorption efficiency of 88.8 percent was accomplished with 79.8 mg at pH 6.50 and temperature of 20 equals 2oC within 360 minutes. BG adsorption rate mechanism was best explained by the pseudo-first order kinetic model (R2 equals 0.903). Dye adsorption behaviour was best explained using Langmuir isotherm (R2 equals 0.980). Reusability of the adsorbent showed that the adsorbent is efficient after three runs. The overall results of adsorption by a way of comparison of the adsorption capacity of this novel material with respect to the contaminants is in this trend: brilliant green greater methyl violet greater simazine. This study indicates that this novel material can serve as new material for the removal of herbicides and dyes as well as vast variety of pollutants from wastewater considering its high adsorption efficiency and its recyclability. Thus, industries can explore the use of this material for the removal of varying pollutants from wastewater.Thesis (MSc) -- Faculty of Science and Agriculture, 202
The photocatalytic properties of zinc phthalocyanines supported on hematite nanofibers for use against methyl orange and Staphylococcus aureus
Get PDFHeterogeneous photocatalysis is a promising approach for environmental remediation from contaminants including microorganisms and organic pollutants. In this work, hematite nanofibers are fabricated and modified with a novel monosubstituted Pc (4) as well as an asymmetrical tetrasubstituted Pc (5) with the aim of creating hybrid photocatalysts. The photocatalytic activities of the unmodified and phthalocyanine modified hematite nanofibers were compared based on their efficiencies in the photoinactivation of S. aureus and photooxidation of methyl orange. For both applications, the hybrid nanofibers were found to be more efficient photocatalysts than the unmodified hematite nanofibers. Comparison of the modified nanofibers (4-Fe2O3 and 5-Fe2O3) showed that they have comparable antibacterial activity while the 5-Fe2O3 nanofibers are the best for the photooxidation of methyl orange. The singlet oxygen generation efficiency, high activity, versatility, regenerability and thus reusability of the fabricated hybrid nanofibers makes them ideal candidates for real life water treatment studies
Zooplankton dynamics of Algoa Bay (South Africa) under varying oceanographic conditions
Get PDFthe ecological significance of ocean plankton in terms of nutrient cycling and energy transfer is widely recognised, as is their mechanistic link with both oceanographic processes and climate. Consequently, plankton are widely regarded as sentinels of climate change, principally owing to their responsiveness to changing environmental conditions. Developing an understanding of the ecological as well as socio-economic consequences associated with changes in marine plankton dynamics has emerged as a key issue worldwide. Though many exciting advances in this respect have been attained with the aid of long-term plankton time series (>50 y), global environmental datasets and innovative meta-analyses, building deep knowledge of regional bio-physical dynamics and responses to specific perturbed states remains an essential component of the collective effort. Algoa Bay, situated on the warmtemperate south-east coast of South Africa presents a unique opportunity to study key elements of plankton ecology relevant to climate change problems in the regional sense. The embayment is locally subjected to frequent wind-driven upwelling and regionally, to periodic mesoscale oceanographic forcing (e.g., large solitary meanders, Agulhas Current intrusions), all of which culminate in a complex physical and biogeochemical environment. Using zooplankton as the focal component and drawing from a multi-year monthly dataset incorporating a bay-scale sampling framework, the present study addressed three key hypotheses pertaining to 1) drivers of spatio-temporal variability, 2) biomass rate of change over temporal scales using time-series analyses, and 3) community responses to a bay-scale biological perturbation event. Zooplankton biomass exhibited prominent seasonal patterns with bimodal peaks corresponding with near-consistent year-to-year autumn and spring blooms. Overall, the spatial trend showed no heterogeneity, though statistical significance between-station variability was noted per season. An analytical framework involving generalised additive models revealed zooplankton spatial heterogeneity in Algoa Bay to be a function of seasonal variation in a suite of physicochemical variables, including the combined effects of temperature, salinity, dissolved oxygen, total nitrogen and silicate, but not ammonium, phosphate or chlorophyll-a (as proxy for phytoplankton). Fronts (including river plumes), warm water intrusion from the Agulhas Current, and wind-driven upwelling were postulated to be key driving forces. Structural breaks analysis performed on station-specific time series revealed significant incremental increases in zooplankton biomass over time, which in turn, corresponded with a gradual decrease in thermocline depth. The most pronounced increasing effect was associated with a period (2013– 14) of amplified land-derived nutrient input and increasing harmful algal bloom (HAB) activity.Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 202
Recruitment disruptors: an exploratory study on the perception of artificial intelligence amongst selected Eastern Cape Province recruiters
No full textThesis (MA) -- Faculty of Humanities, Psychology, 202
A simple quinoline-thiophene Schiff base turn-off chemosensor for Hg2+ detection
Get PDFA new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips
The impact of urban gardening on household food security: evidence from Makhanda East, Eastern Cape Province, South Africa
Get PDFUrban gardening in townships is a common coping strategy employed by poor inhabitants to improve food security, earn income through sales, and generate cost-savings through home consumption of fresh produce. Food security is a cornerstone of human development and welfare, and the achievement thereof remains a global challenge. The majority of academic research and policy documentation traditionally positions food insecurity as a rural phenomenon. However, recent trends point to an increase in food insecurity in urban areas, particularly in low-income areas such as townships. In South Africa, rapid urbanization has led to burgeoning townships and rapidly expanding low-income informal settlements characterised by poverty, unemployment, and food insecurity. Research concerned with the role that urban agricultural production plays in contributing to the food security of poor households is scarce and not well understood. This research, therefore, aimed to contribute to the limited research which specifically examines urban food security, and the role urban agriculture play in the achievement of household food security. The study employed collective action theory and utility theory to firstly provides an in-depth examination of the determinants of participation in urban gardening using Probit regression modeling. The second research objective was to perform an impact evaluation of participation in urban gardening on selected household food security indicators including Household Dietary Diversity Scores (HDDS), the Household Hunger Scale (HHS) and the Coping Strategy Index (CSI) using Propensity Score Matching (PSM). Purposive and snowball sampling methods were employed to obtain a sample of 60 urban gardeners and a control group of 55 non-gardening households from Extension 6, 7 and 10 townships as well as Joza Location in Makhanda East, Eastern Cape Province. Households were surveyed using a structured household food security questionnaire. A focus group discussion was held with the Linomtha Community Garden members and key informant interviews were undertaken with important stakeholders such as the local extension officers. Descriptive analysis revealed that urban gardening households (UGs) had older household heads who were less educated, and that land and water availability were the dominant constraints to increases in agricultural production. Results from the probit and average marginal effects models showed that the likelihood of participation significantly increased when household unemployment and dependency increased and that households who were engaged in off-farm economic activity were more likely to participate in urban gardening. The impact evaluation was performed using PSM and Average Treatment Effect on the Treated (ATT). Analysis illustrated that participation in urban gardening does significantly reduce both the full CSI and Reduced CSI. Thus, participation in urban gardening improves the food security of participating households by significantly reducing the frequency of participating households (UGs) applying undesirable coping strategies such as sending children elsewhere other than the household, borrowing food from other households and reducing the number of meals eaten in a day due to food shortages. This study posits that urban gardening alone will not eradicate the rampant food insecurity and poverty which pervades in South Africa’s townships. However, urban gardening participation does contribute to the construction of a sustainable, urban livelihood by reducing the number and severity of the undesirable coping strategies that food insecure households employ by providing some nutritious produce as well improved social capital through gardening networks and supporting institutions. It is recommended that policy makers, at a national and municipal level, need to create a clearer directive for the integration of urban food production into the urban food marketplace thus increasing access to income generating channels for small-scale home, and community gardeners. Co-operation between private and public institutions for food security and urban gardeners needs to be fostered and awareness of opportunities to participate in urban gardens needs to be improved. Central to the developmental challenges that rapid increases in urbanization and food insecurity in poor urban areas, is the need for national and local governments to improve access to economic opportunities in township areas - both in urban agriculture and in other, skills intensive sectors.Thesis (MEcon) -- Faculty of Commerce, Economics and Economic History, 202