11613 research outputs found
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Spectroscopic behaviour of copper(II) complexes containing 2-hydroxyphenones
No full textTheoretical investigations by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods shed light on how the type of ligand or attached groups influence the electronic structure, absorption spectrum, electron excitation, and intramolecular and interfacial electron transfer of the Cu(II) complexes under study. The findings provide new insight into the designing and screening of high-performance dyes for dye-sensitized solar cells (DSSCs).Publisher's versio
Rethinking blended high yielding seed varieties and partial-organic fertiliser climate smart agriculture practices for productivity and farm income gains in the drylands of Zimbabwe
No full textMost blended climate smart agriculture (CSA) technologies focusing on seed-fertilizer combinations have either been marginally adopted or dis-adopted by smallholder farmers due to the nature of design and implementation. A data science research approach was used with 380 households in the mid-Zambezi Valley of Zimbabwe. The study examines impact of adopting a farmer initiated CSA practice combining improved sorghum seed variety and partial-organic fertilizer on household income and productivity among smallholder farmers in the drylands of Zimbabwe. A cross sectional household survey using multi stage sampling with purposive and stratified proportionate approaches was conducted. A structured questionnaire was utilized for data collection. Endogenous Switching Regression (ESR) model was utilized to account for self-selection bias of sampled farmers. Overall, a combination of farm specific factors (arable land, variable costs) and external factors (distance to the market, value of aid) have a bearing on the adoption decision and the associated impact on productivity and income. The counterfactual analysis shows that farmers who adopt the technology are relatively better off in productivity and income. Our findings highlight the significance of improving access to CSA practices which are initiated by the farmers using a bottom-up approach since they suit their operating contexts better. Tailor-made supporting programs including farmer networking platforms and decentralized markets need to be designed and scaled up by policymakers to encourage farmers to adopt blended soil fertility CSA practices in their farming practices. Networking arrangements need to be strengthened through local, government and private sector partnerships along the sorghum value chain.Publisher's versio
The makings of field rangers in Limpopo province: An exploratory ethno-perceptive study
No full textDissertation (M.A. (Anthropology))--University of the Free State, 2022Field rangers are the first and last line of defense in environmental protection, working on the ground to ensure the integrity of conservation areas. In the previous decade, the ranger’s responsibilities have shifted from a conservation-based outcome to para-militarization in protecting high-value species, such as the rhino. Increasingly, rangers are drawn into law enforcement responsibilities and away from the breadth of other duties relating to biodiversity and conservation. Recruits often originate from communities living around protected areas, lacking alternate employment opportunities. Rangers often live among those connected to transnational wildlife trafficking networks, making them targets for intimidation and corruption. This further contributes to the social and familial pressures rangers face from hostile or co-opted community members involved in poaching or actively supporting poaching networks. Due to these circumstances, rangers may place their lives at risk daily in carrying out their work and may face increasingly significant challenges. Although some literature is available on rangers’ activities in preserving biodiversity globally, little is known about the rangers themselves. This narrative is not an exhaustive work on them but instead offers a glimpse, lifting the veil for the reader to see and experience a moment in the lives of the rangers. The research focuses not on military perspectives but on the human dimension behind firearms and uniforms
Susceptibility tests and predictions of transporter profile in Serratia species
No full textDisinfectants and biosecurity are critically important to control microbial diseases. Resistance
to disinfectants compromises sectors such as agriculture and healthcare systems. Currently,
efflux pumps are the most common mechanism of antimicrobial resistance. This study aimed to
identify the efflux transporters responsible for disinfectant resistance in a multidrug-resistant isolate
Serratia sp. HRI compared to a susceptible Serratia sp. type strain. An efflux system profile was generated
using the Transporter Automatic Annotation Pipeline (TransAAP) for both isolates. Thereafter,
the efflux pump inhibitors, reserpine (RSP) and carbonyl cyanide 3-chlorophenylhydrazone
(CCCP) were used to reveal the role of efflux pumps in susceptibility to three disinfectants (Didecyldimethylammonium
chloride, HyperCide®, and benzalkonium chloride). Interestingly, the resistant
isolate had fewer efflux systems in total compared to the type strain and fewer efflux systems classified
as resistance efflux pumps. After the addition of RSP, a significant reduction in resistance
capabilities against all three antimicrobials was observed for both isolates. However, CCCP supplementation
produced mixed results with some outcomes suggesting the involvement of the Eagle
effect. This study provides evidence that efflux pumps are responsible for the disinfectant resistance
phenotype of the Serratia species due to the increased susceptibility when efflux pump inhibitors
are added.Publisher's versio
The role of social entrepreneurship in reducing poverty: A case study of Anchor of Hope
No full textDissertation (MDS (Development Studies))--University of the Free State, 2022Social entrepreneurship has, over the years, come to be known as an important element
in the development of society at large (Ferri, 2014:12). Governments and researchers such
as Ferri (2014) have displayed interest in understanding this phenomenon. The role of
social entrepreneurship in reducing poverty is what the researcher is trying to uncover in
this study. Social entrepreneurship is defined as an action that is innovative in using
resources to pursue a need in an ever-changing world to address social needs (Mair &
Marti, 2006). Furthermore, social entrepreneurship is said to be associated with using
enterprise methods to satisfy social reasons (Dey & Teasdale, 2013). Drawing knowledge
from the definition, it appears that social entrepreneurship involves financial gain or profit
and giving social value. The social value in this study links to poverty reduction. Social enterprises are therefore
seen as a critical factor in development and poverty alleviation (Mair & Marti, 2006).
Poverty has different definitions, and it is looked at from different perspectives. Often, there
is a claim that poverty must be based on logical argument and science, but there is no
correct, scientifically agreed definition because it is inevitably a political concept and, thus,
an inherently contested one (Ludi, 2007). One definition is that poverty is a state whereby
a person is poor because his or her income level falls below the minimum level necessary
to meet basic needs (World Bank, 2019). Millions of people around the world live in
extreme poverty and hunger, and many people in extreme poverty are found in Africa. This
will be looked at in length in the literature review section. South Africa has also proven to
have high levels of inequality, poverty, and unemployment. The South African government
has, therefore, called upon businesses to play a role in transforming and developing better
conditions for all to live in. Business on its own is broad, and it calls on all sectors within it
to play a part. One of them being social entrepreneurship. It can be used as an innovative
way of fighting poverty and other social and economic ills that hinder the development of
this nation (Mohammed & Ndulue, 2017). Non-profit organisations (NPOs) are also
encouraged to take a more entrepreneurial and business-oriented approach in order to
generate revenue and be self-sustaining while providing social value services (Mohammed
& Ndulue, 2017)
Effect of ꞷ-3 lipid sources on layer performance and egg quality during peak production
No full textDissertation (M.Sc.(Agriculture))--University of the Free State, 2022The aim of this study was to investigate the effect of dietary omega-3 lipid sources on the production performance of laying hens during the peak laying period. Experimental treatments consisted of a control diet containing 0% supplementary lipid and four lipid sources (varying in omega-3 fatty acid chain length) mixed into the basal diet at 1.5%, respectively. The lipid sources used were fish- (EPA, C20:5 & DHA, C22:6), soybean- (ALA, C18:3), linseed- (ALA, C18:3) and echium oil (SDA, 18:4). A total of 150 Hy-Line Silver-Brown hens (21 weeks of age) were allocated to five experimental diets (n=30 birds/treatment). During weeks 24, 28, 32, 36 & 40, all eggs produced were recorded and weighed individually, while feed intake and body weight of birds were determined. Data were pooled to calculate the average production performance of the peak laying period. A one-way ANOVA procedure was used to analyse the data. Results indicated that omega-3 lipid sources had no effect on feed intake, feed efficiency or egg output. Birds from the control treatment recorded lower (P< 0.05) body weights (1729 g). Although hen-day egg production was lower for the soybean oil treatment compared to linseed oil (94.3% vs. 96.7%), sellable eggs did not differ between treatment means. No clear trends were observed for the effect of omega-3 lipid source on peak production performance of laying hens. The omega-3 lipid source had minor effects on peak production performance of laying hens
Ventusium: a place of wind
No full textDissertation (M.Arch. (Architecture))--University of the Free State, 2022Th is book concerns itself with the infl uence that substance has on architecture and architectural engagement. Architectural substance is explored through the register of the imagination, a term coined by James K.A. Smith to refer to human’s
everyday understanding of the world. Th e register of the imagination is informed via the senses through substance, so the senses and their interaction with the world form a large part of the practical discourse of this document. Th e senses
lead to practical ways in which to create architecture which includes the entire body and leads to meaningful engagement with the world, and the creation of meaning through the mythology of the building
Soil organic matter storage in irrigated Tsitsikamma dairy farms with minimum tilled pasture mixtures: case studies
No full textIn recent years, pasture production changed from conventional tilled single pastures to minimum tilled mixed pastures in the Tsitsikamma region, South Africa. However, storage of soil organic matter (SOM) under minimum tilled mixed pastures is not yet quantified. This study evaluated SOM indices in the upper 60 cm soil of six-year-old mixed pastures in the Upper (UT) and Lower (LT) Tsitsikamma regions. Soil samples were collected at 0–15, 15–30, 30–45, and 45–60 cm soil layers of five farms (F1, F2, F3, F4, and F5) treated with different rates of fertilizer (NPK) alone and in combination with dairy effluent (DE) and/or poultry manure (PM). Results of this study indicated that there were no significant differences in bulk density, total nitrogen (N), and rate of potentially mineralizable N (PMN) between farms in the UT region. In the LT region, NPK, DE, and PM combinations improved soil C accumulation relative to the soil application of NPK. Higher C/N ratios in the LT region suggested adequate C for microbial energy and maintenance. Integrating manure into minimum tilled pasture mixtures as a replacement for synthetic fertilizers seems to be a feasible option to promote SOM storage, but remains only feasible by applying site-specific management strategies.Publisher's versio
An artificial neural network model for pediatric mortality prediction in two tertiary pediatric intensive care units in South Africa. A development study
No full textObjectives: The performance of mortality prediction models remain a challenge in lower- and middle-income countries. We developed an artificial neural network (ANN) model for the prediction of mortality in two tertiary pediatric intensive care units (PICUs) in South Africa using free to download and use software and commercially available computers. These models were compared to a logistic regression model and a recalibrated version of the Pediatric Index of Mortality 3.
Design: This study used data from a retrospective cohort study to develop an artificial neural model and logistic regression model for mortality prediction. The outcome evaluated was death in PICU.
Setting: Two tertiary PICUs in South Africa.
Patients: 2,089 patients up to the age of 13 completed years were included in the study.
Interventions: None.
Measurements and Main Results: The AUROC was higher for the ANN (0.89) than for the logistic regression model (LR) (0.87) and the recalibrated PIM3 model (0.86). The precision recall curve however favors the ANN over logistic regression and recalibrated PIM3 (AUPRC = 0.6 vs. 0.53 and 0.58, respectively. The slope of the calibration curve was 1.12 for the ANN model (intercept 0.01), 1.09 for the logistic regression model (intercept 0.05) and 1.02 (intercept 0.01) for the recalibrated version of PIM3. The calibration curve was however closer to the diagonal for the ANN model.
Conclusions: Artificial neural network models are a feasible method for mortality prediction in lower- and middle-income countries but significant challenges exist. There is a need to conduct research directed toward the acquisition of large, complex data sets, the integration of documented clinical care into clinical research and the promotion of the development of electronic health record systems in lower and middle income settings.Publisher's versio
Priming effect of leaf rust and salicylic acid in Russian wheat aphid resistance
No full textThesis (Ph.D.(Plant Sciences))--University of the Free State, 2022Wheat (Triticum aestivum L.) is one of the primary sources of carbohydrates for humans and livestock (Karakas et al., 2021). It is an essential cereal for the human diet and contributes to global food security. Almost 50% of calories for human consumption come from grains; out of this, about a quarter comes from wheat (González-Esteban, 2017).
Wheat grain is a rich source of carbohydrates, dietary fibre, vitamins (B-vitamins) and phytochemicals (Shewry and Hey, 2015). In addition to this, it has 13-17% bran, 2-3% germ and 80-85% mealy endosperm (Šramková et al., 2009). Wheat is a significant source of globulin, albumin, and amphiphilic protein content (Dubreil et al., 1998). Furthermore, wheat provides lipids and essential minerals like calcium, copper, iron, phosphorus, potassium, manganese, magnesium, and zinc (Rachon et al., 2015).
The current global wheat production is 642 million tons, and the future (2050) demand is about 840 million tons. This demand may be attained on limited resources (water, land) if new agronomic, physiological and genetic research strategies and practices are introduced (Sharma et al., 2015). Domestication of wheat occurred 10,000 years ago, and wheat spread worldwide as a major cereal crop. Its diverse adaptability to different environments makes it easy to domesticate. Genetic miscellany (ploidy level) of wheat and its progenitors reward novel diversity quickly in different climatic zones (Dubcovsky and Dvorak, 2007).
Commercial wheat cultivation started in South Africa in the early 1910s in Cape Town, with seeds introduced earlier by the Dutch traders (Nhemachena and Kirsten, 2017), and has become the second most crucial grain crop cultivated in South Africa after maize (Anonymous, 2021; Bester, 2014). Both tetraploid and hexaploid wheat cultivars are produced in approximately 90% of the available agro-climatic regions of South Africa (Lantican et al., 2005). The dominant wheat-producing areas are the Western Cape (winter rainfall, mainly dryland), Free State (summer rainfall, both dryland and irrigated), Northern Cape (irrigated) and North West (mainly irrigated) provinces. Even though cultivation occurs in winter and summer rainfall regions, between 1983 and 2008, wheat was cultivated predominantly under dryland conditions where annual production averaged 1.5 to 3 million tonnes (2-2.5 tons/ha) (Nhemachena and Kirsten, 2017). However, about 30% of harvested wheat is produced under irrigation, where the yield potential varies between 6 to 12 tons/ha, with higher winter temperatures being the main limitation in the lower-yielding areas (Anonymous, 2021). The major companies or institutions supplying improved wheat cultivars in South Africa are Sensako (now part of Syngenta), Pannar Seed (Corteva AgrisciencesTM) and the Agricultural Research Council-Small Grains (ARC-SG) (Nhemachena and Kirsten, 2017). The wheat varieties are constantly improved for high yield and tolerance or resistance to prevailing drought, salinity, heat, pests and diseases. In South Africa, the wheat industry contributes about USD 40 billion to the gross value of agricultural production (Jankielsohn, 2016) and 28 000 jobs (Bester, 2014).
Some pathogens (causing diseases like rust and powdery mildew) and pests similar to the Russian wheat aphid (RWA) significantly reduce yield and flour quality (Kazi et al., 2013). Russian wheat aphid infestations significantly challenge successful wheat production (Njom et al., 2017) because they reduce wheat yield and deteriorate flour quality (Girma et al., 1993). The emergence of RWA biotypes with increased virulence threatens wheat production and reduces the desired targets to meet the South African demand for high-quality wheat grain