11613 research outputs found
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Octakis(dodecyl)phthalocyanines: influence of peripheral versus non-peripheral substitution on synthetic routes, spectroscopy and electrochemical behaviour
No full textNon-peripherally octakis-substituted phthalocyanines (npPc’s), MPc(C12H25)8 with M = 2H (3) or Zn (4), as well as peripherally octakis-substituted phthalocyanines (pPc’s) with M = Zn (6), Mg (7) and 2H (8), were synthesized by cyclotetramerization of 3,6- (2) or 4,5-bis(dodecyl)phthalonitrile (5), template cyclotetramerization of precursor phthalonitriles in the presence of Zn or Mg, metal insertion into metal-free phthalocyanines, and removal of Mg or Zn from the phthalocyaninato coordination cavity. The more effective synthetic route towards pPc 8 was demetalation of 7. npPc’s were more soluble than pPc’s. The Q-band λmax of npPc’s was red-shifted with ca. 18 nm, compared to that of pPc’s. X-ray photoelectron spectroscopy (XPS) differentiated between N–H, Nmeso and Ncore nitrogen atoms for metal-free phthalocyanines. Binding energies were ca. 399.6, 398.2 and 397.7 eV respectively. X-ray photoelectron spectroscopy (XPS) also showed zinc phthalocyanines 4 and 6 have four equivalent Nmeso and four equivalent N–Zn core nitrogens. In contrast, the Mg phthalocyanine 7 has two sets of core N atoms. One set involves two Ncore atoms strongly coordinated to Mg, while the other encompasses the two remaining Ncore atoms that are weakly associated with Mg. pPc’s 6, 7, and 8 have cyclic voltammetry features consistent with dimerization to form [Pc][Pc+] intermediates upon oxidation but npPc’s 3 and 4 do not. Metalation of metal-free pPc’s and npPc’s shifted all redox potentials to lower values.Publisher's versio
Learning mathematics through WhatsApp groups in university preparatory program during the COVID-19 pandemic
No full textThis study examined the impact of learning through social media (WhatsApp learning groups) on university students' mathematics achievements in the first-year university preparatory program when they engaged in some form of social media learning interaction compared with students who did the same module with a traditional face-to-face interaction learning approach. The study was undertaken using a quantitative research method. It employed a randomised Post-Test-Only with a Non-equivalent Groups design to investigate the only statistically significant difference between university students who studied through the traditional face-to-face lecturing approach and students who utilised a blended approach to learning mathematics. The study population comprised first-year university students enrolled for the university extended programme offered by all universities in South Africa. The sample consisted of 192 experimental groups and 341 control group students conveniently sampled from a university in South Africa. The main instruments used in this study were two standardised semester exams. These tests were checked and moderated by senior mathematics lecturers to ensure they conformed with the module content and satisfied all assessment policies of the university. The Cronbach alpha coefficient was used to measure the consistencies in these two-semester exams. The study's main finding showed no statistically significant difference in results between students who studied Mathematics through a face-to-face lecturing approach and students who studied mathematics through a blended learning approach. The study concludes that the latter performed slightly better than students in the former, confirming that a WhatsApp learning group can be a viable alternative to the teaching and learning at the university when face-to-face learning is not possible, as for an example in the Covid-19 era. The study recommends that more profound research be conducted to identify and analyse positive indicators when learning is done through social media interaction.Publisher's versio
Toorwatter: a wellness retreat that captures the stories of Toorwater, a natural hot spring in the Klein Karoo
No full textDissertation (M.Arch. (Architecture))--University of the Free State, 2022In the natural landscape of the Klein Karoo, narratives flow from the spring at Toorwater. The research question asks how the stories flowing from Toorwater can be translated into a wellness retreat that celebrates regionalist placemaking
and sparks new stories? Previous examples in South Africa have illustrated the use of natural hot springs for resorts, while this design proposes using the natural hot spring as a wellness retreat, focusing on the therapeutic effect on
physical and spiritual well-being. This proposal suggested buildings that focus on the natural landscape and narratives of place. The research question was approached through the exploration of local narratives and how to establish an
appropriate architectural language in the Klein Karoo. This dissertation will provide a better understanding of how the narratives embedded in Toorwater can be told through architecture rooted in place
Evaluating cowpea mutant genotypes for grain yield and nutritional value in South Africa
No full textDissertation (M.Sc.(Plant Breeding))--University of the Free State, 2022Cowpeas produce a substantial amount of grain, which is a significant source of vitamins, minerals and protein to disadvantaged people with limited access to adequate nutrients. Improved cowpea genotypes have been introduced through new breeding techniques such as mutagenesis to increase the phenotypic, genetic and nutritional diversity of the crop. The objectives of this study were: 1) to determine the phenotypic diversity and characterise cowpea mutants and normal genotypes for grain yield and yield components, to identify superior cowpea mutants and normal genotypes and to determine the correlation between all measured characteristics, 2) to evaluate the variability of cowpea mutants and normal genotypes for protein content, selected mineral elements, phytic acid and the potential bioavailability of iron (Fe) and zinc (Zn), to identify superior cowpea mutants and normal genotypes, and to determine the interrelationship between all measured characteristics, and 3) to determine genotype by environment (GE) interaction, to identify superior genotypes for grain yield and to determine the adaptability and stability of cowpea mutants and normal genotypes in South Africa. Thirty-one cowpea genotypes (16 Namibian mutants, seven International Institute of Tropical Agriculture (IITA) genotypes and eight South Africa genotypes) were planted in five different environments in South Africa during the 2021/2022 cropping season.
Significant (P ≤ 0.05) genotype and GE interaction effects were observed for grain yield, yield components, protein content, minerals, phytic acid and potential mineral bioavailability. Broad-sense heritability (H2) values above 50% were observed for yield components, protein, mineral elements, phytic acid and potential mineral bioavailability, while low H2 values below 50% were observed for grain yield and Boron (B), indicating the complexity in selection and genetic improvement of these traits. Superior Namibian mutants (ShR10P12, ShR3P4, ShR4P1 and BrR11P2), IITA genotype (98K-476-8) and South African genotype (Enchore) for grain yield were identified. Superior Namibian mutants (ShL3P7-2, ShR3P4, ShR4P1, BrR11P11, BrR4P11, NKL9P7, NKR8P9, NKR9P9 ShR2P11, BrR11P2, ShL2P7, ShR3P4 and NKRuP5), IITA genotypes (98K-476-8, IT82E-18, IT93K-452-1, IT99K-573-2-1 and ITOOK 1263), and South African genotypes (Oloyin, Orelu, Pan 311, Bechuana White, Enchore and Glenda) for protein content, Fe and Zn concentration were also identified. The IITA genotype (IT93K-452-1) and South African genotypes (Oloyin and Orelu) had a potential of good Fe bioavailability. All cowpea mutants and normal genotypes had a potential of poor Zn bioavailability. High yielding and stable Namibian mutants (NKL9P7, ShR10P12 and ShR2P11), IITA genotype (ITOOK 1263) and South African genotype (Agrinawa) were identified. Two mega-environments, namely, 1) Taung and Mafikeng, and 2) Mafikeng, Bloemfontein, Polokwane and Potchefstroom were identified, indicating broad adaption of the genotypes. Potchefstroom and Taung were identified as ideal environments for evaluation of cowpea genotypes. Significant positive correlations between grain yield with almost all yield components were observed. Significant positive correlations of protein content with mineral elements and phytic acid were also observed, indicating the potential to simultaneously select these traits. Namibian mutants (NKR1P3, BrR11P2, ShL2P7, ShR2P11 and ShR10P12), IITA genotype (98K-476-8) and South African genotypes (Glenda, Dr Saunders, Enchore and Oloyin) were associated with high grain yield. Namibian mutants (ShR10P12, ShR3P4, ShR9P5, BrR11P11, BrR11P2, BrR4P11, NKR1P3, NKR9P9 and NKRuP5), IITA genotypes (IT07K-292-10, IT07K-318-33, IT82E-18 and IT99K-573-2-1), and South African genotypes (Agrinawa, Bechuana White and Dr Saunders) were associated with high protein content, manganese (Mn), phytic acid, Molar ratio of phytic acid with iron (PA:Fe), Molar ratio of phytic acid with zinc (PA:Zn), and ash content. These genotypes have a potential of long-term profitability to the agricultural production industry
Food insecurity and health outcomes during the coronavirus pandemic in South Africa: a longitudinal study
No full textBackground
Given that South Africa experienced significant food insecurity even before the COVID-19 pandemic, it is not surprising that the pandemic would result in even greater food insecurity in the country. This paper provides additional evidence on the relationship between food insecurity and health.
Methods
Data came from the National Income Dynamics Study-Coronavirus Rapid Mobile Survey, a longitudinal survey of adult South Africans. Health was a self-reported indicator of general health, while food insecurity was measured by household hunger, the frequency of household hunger, and households running out of money to buy food. We performed descriptive and econometric analyses.
Results
Food insecurity has remained high even in the face of greater re-opening of the economy. Moreover, among hunger-affected households, between a quarter and a third struggled with hunger almost daily or daily. Belonging to a hunger-affected household was associated with a 7-percentage point higher probability of worse health compared to not experiencing hunger. Compared to being unaffected by hunger, being hungry everyday was associated with a 15-percentage point higher probability of worse health in wave 1, an effect that became statistically insignificant by wave 4.
Conclusions
These results show the enormity of the hunger problem in South Africa and its adverse effects on health. In the face of economic uncertainty and the removal of COVID-19 palliatives like the grant top-ups, we enjoin policy makers to protect the vulnerable from food insecurity by continuing the implementation of anti-hunger policies and other measures that enhance food security in the country.Publisher's versio
The evaluation of a continual disinfection program on a commercial broiler chicken farm
No full textThe rise of antibiotic resistance as a global health threat has been linked to overuse of antibiotics, in particular, in the agricultural sector. A post-antibiotic world is fast approaching where antibiotics may be completely ineffective. To delay and prepare for this reality, alternative solutions to the use of antibiotics in animal production are required. Biosecurity describes some of the oldest techniques related to animal health, including infectious agent destruction and exclusion. Novel solutions to biosecurity must be investigated, however the possible loss of production related to halting antibiotic use is a major risk to food security. This study focused on assessing a continuous disinfection program using Virukill®, a modified- didecyldimethylammonium chloride-based disinfectant, for post-placement cleaning and disinfection, direct spray, and administration in water supply, at a commercial scale. This work provides a proof of concept for industrial application of a continuous disinfection program as a biosecurity measure in poultry production. Through bacterial and viral evaluation methods it was established that the continuous disinfection program was equal or better than standard aldehyde disinfectants in reducing viral loads. Organisms that survived the cleaning and disinfection process were also isolated and identified with molecular methods. The possibility of disinfectant resistance was also investigated but no evidence of resistance was observed. It was established that Virukill® was more effective than DDAC and BC in inhibiting the growth of organism isolated. Through growth performance studies this work establishes for the first time that the Virukill® continuous disinfection program improves performance of broilers, and a correlation was established between cleaning efficacy and performance. This work provides a viable alternative biosecurity-based alternative to the use of antibiotics in broiler production
Critical success factors for women smallholder-farmers transforming into commercial farmers, Lejweleputswa district municipality: Free State
No full textDissertation (MBA (Business Administration))--University of the Free State, 2022Smallholder farmers play a crucial role worldwide in food security and economic growth. The study explores the transformation of women who are smallholder farmers to become commercial farmers, focusing on the Lejweleputswa District Municipality, Free State. However, women smallholder-farmers encounter numerous challenges that hinder the process. The study investigates inhibiting factors and identifies success factors that can accelerate transformation.
Qualitative research was employed to gather data in the study using semi-structured interviews. The methodology employed assisted the researcher in discovering why women smallholder-farmers transform to become commercial farmers, the challenges inhibiting transformation, and the success factors contributing to successful change. Recommendations are made based on the results obtained during the interviews. These include doing due diligence with regards to lack of natural resources. As well as women smallholder farmers establishing and creating value chains in the area where they live. Furthermore, the study recommends that both the formal markets and women smallholders should enter into memorandum of understanding in terms of the specifications of agricultural produce. Results showed that more still needs to be done to avail resources and provide access to markets to transform women in smallholder farming to commercial farming
Employee morale of farmworkers at Dihoai chicken farm, Welkom
No full textDissertation (MBA (Business Administration))--University of the Free State, 2022The study aims to investigate the factors affecting the morale of farmworkers at Dihoai
Chicken Farm, Welkom. The sample size of the study was 25 participants. The data
was collected through semi-structured interviews and analyzed through thematic
analysis. The study is based on literature. The study's results identified factors that
affect the morale of the farmworkers as their remuneration, job security, rewards,
recognition and training. The organisation should consider introducing a reward and recognition system and reviewing its remuneration packages and training and development program
Behavioural and psychological control during adolescence: an ecological systems perspective
No full textThis study investigated the extent and the nature of the behavioural and psychological control experienced by adolescents
within four contexts (parental, peer, school, and community) of their everyday lives. The adolescents (n = 463; female =
52.5%, black African = 69.3%; mean age = 15.69 years, SD = 2.86 years) were from six public high schools in the Eastern
Cape of South Africa. The participants completed adapted versions of the Parents’ Psychological Control Scale and the Peer
Control Scale. Multivariate analyses of variance revealed that in the school and community contexts, early adolescents and
female participants experienced significantly higher levels of control than older adolescents and male participants. Female
early adolescents experienced significantly higher levels of control (school behavioural control, community behavioural
control, and community psychological control) specific to the school contexts which was in the form of psychological
control. Findings of this study can inform community mentors and school counsellors of the important psychological and
behavioural impact that community norms and school values have on how adolescents experience their social worlds and
negotiate the boundaries of various social systems
Layering skin as space to reweave the existing Johannesburg Gasworks into a fashion design school and textile recycling hub
No full textDissertation (M.Arch. (Architecture))--University of the Free State, 2022A comparison between architecture, fashion and skin lead to the assemblage of different skins and how different perspectives of skin can be employed in an architectural response. The dissertation considers the possible consolidation between skin, fashion and architecture and its application to the Johannesburg Gas Works complex in Cottesloe. Fashion elicits emotive experiences that encompass the dresser and dweller to craft and embody identity and formulate expressions through the act of dressing. The principal aim of the investigation is to explore how architecture and the application of skin as dwelling in the design of a Fashion design school and Textile recycling hub can elicit the different experiences of fashion in a space inspired by textiles. Fashion is a valuable art form that can be utilised in various architectural explorations to encourage the investigation into the skin as an architectural form giving tool. The Fashion Hub contrasts the Gasworks previous programme and form. The Fashion Hub creates the opportunity to engage with the surrounding context, communities and Johannesburg Fashion District. The theoretical discourse investigates how fashion in architecture, skin as a metaphor for a house, the five skins of ecology, and rejuvenating architecture can be applied to the architectural design process to be integrated into a synthesis of architectural expressions. The design process uses fashion as a catalyst for developing an architectural form with the implementation of skin as space and skin as an expression of fashion in the design. The engagement of skin with an investigation into skin translucency, shedding, expression, and skin as a metaphor to construct a narrative through fashion can be employed in architecture that is not confined to only fashion design. The engagement of skin in the theoretical underpinning section showed that different skins could be developed within the Fashion design school and Textile recycling hub to encourage interaction between people and fashion through architecture