Synthesis, X-Ray characterization, spectroscopic and Hirshfeld surface analysis of dimeric metal centers featuring phenacyl-esters
- Authors: Qomfo, Vuyiseka
- Date: 2024-12
- Subjects: Spectrum analysis , Spectroscopic imaging , Diagnostic imaging -- Digital techniques
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/69426 , vital:77254
- Description: In this study, the synthesis and characterization of carboxylate paddlewheel copper complexes were investigated and reported. The complexes consist of O-, and N- donor ligands which coordinated in the apical positions of the copper (II) paddlewheel complexes. The primary focus was the investigation of the influence of the incoming substituents on the structure; more especially with regards to the spectral properties and thermal properties of the synthesized compounds. Synthesized complexes ranged from simple mononuclear complexes and dinuclear dimers to supramolecular 1D networks and a tetranuclear copper (II) compound. Characterization of complexes was done using analytical, and spectroscopic techniques such as single crystal diffraction studies, FT-IR spectroscopy, thermal analysis and Hirshfeld surface analysis. Structural analysis of the mononuclear complex obtained in the reaction of the Cu2(o-CH3-PhCO2)4(THF)2 with the ligand ,2-oxo-phenylethylnicotinate, revealed a square-planar geometry. The series of dinuclear paddlewheel complexes obtained with ligands (L = THF (1), C4H8O (2), C14H11NO3 (3)) revealed a square pyramidal geometry with the methyl-substituted phenyl carboxylate groups bridging the two copper atoms in the syn-syn coordination mode. Extended supramolecular complexes were synthesized via the reaction of three synthesized structurally bifunctional organic ligands and the tetrakis(μ-carboxylato-O,O)dicopper(II) core. Two of the six reactions synthesized successfully to form paddlewheel cage type structures; resulting in dinuclear paddlewheel complexes with four carboxylate ligands occupying the equatorial positions and the bifunctional ligands coordinating in the apical positions. Four of the nine reactions produced mononuclear copper complexes. Due to the inconsistent power supply because of load-shedding, the other three crystals synthesized could not be confirmed by single-crystal diffraction before the submission of this thesis. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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- Date Issued: 2024-12
Biology and management of the fruit piercing moth Serrodes partita in citrus orchards
- Authors: Mushore, Tapiwa Gift
- Date: 2024-10-11
- Subjects: Baculoviruses , Moths Monitoring , Pests Control , Insect traps , Citrus Diseases and pests South Africa Kat River Valley , Catapult moth
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466792 , vital:76779 , DOI https://doi.org/10.21504/10962/466792
- Description: The fruit-piercing moth, Serrodes partita (Fabricius) (Lepidoptera: Erebidae), is a polyphagous, multivoltine pest of citrus. This insect has a distinct geographical separation between its larval and adult stages, each with different feeding patterns. During the larval stage, it primarily acts as a forest defoliator, feeding mostly on Jacket plum, Pappea capensis Eckl. & Zeyh. (Sapindaceae). In contrast, the adult stage of this moth feeds on both tropical and subtropical fruit, including citrus and can cause serious economic losses. The adult moth uses its sclerotised proboscis to pierce the skin of ripening or ripe fruit, from which it extracts the juice. This piercing action initiates a fermentation process within the fruit, attracting other secondary-feeding moths, commonly referred to as fruit-sucking moths. As a result of the feeding activity, the affected fruit eventually rot, drop to the ground, and become unsuitable for the market. Serrodes partita exhibits an outbreak life strategy, reoccurring every 5 to 10 years. In South Africa's Eastern Cape Province, specifically in the Upper Kat River Valley, citrus growers have expressed concerns about the impact of this moth on soft citrus (Satsumas and Clementines). This raises the possibility of a shift in the population dynamics of S. partita, where these occurrences become more frequent and less sporadic. Such a trend poses a significant threat to fruit arboriculture in the Eastern Cape region. Currently, there are limited management strategies available for managing fruit-piecing moths. The use of pesticides is not a feasible option for ripe or nearly ripe fruit, and is ineffective against the adult moth. Alternative control methods, such as orchard netting and light barriers, either come with high costs or are impractical for large-scale citrus production. Given the limited range of management options, combined with the moth's tendency for sudden outbreaks, citrus growers find themselves without effective means to manage this pest. The objective of this study was, therefore, to investigate the biology of S. partita and explore various control options to effectively manage this pest. Research focused on the biology and laboratory rearing of larval stages of S. partita. The flight behaviour, feeding patterns, and preferences of adult S. partita within citrus orchards were also explored. The aim was to elucidate key fundamental aspects, including whether the same population frequents a particular orchard, and if infestations within orchards exhibit a specific direction. Lure type and lure presentation method trials were conducted to determine the most effective lure and trap design. Seasonal monitoring of S. partita in soft citrus orchards was conducted over three years to determine its outbreak status in the Committee’s Drift area and the role of weather variables in the activity of the moth. Damage assessments were also conducted alongside monitoring to determine the level of damage inflicted by S. partita. Natural enemies associated with S. partita were explored to determine the prevalence and causes of mortality in late instars during laboratory rearing. Rearing S. partita on an artificial diet was unsuccessful despite several modifications. The moth, however, completed its entire life cycle on its natural host, P. capensis in the laboratory. The total life cycle from egg to adult took 80.7 ± 3.6 days, the larval stage lasted 52.3 ± 2.8 days, and the pupal stage lasted 25.8 ± 3.6 days at 21°C. The investigation into the biology of S. partita also brought attention to the most susceptible stages of its growth, with high mortality rates recorded among neonates and late instars. The findings of the study revealed directional patterns of moth infestations, with higher numbers observed at the orchard's periphery leading towards natural vegetation. This raises the prospect of using sacrificial rows on the edge of a citrus orchard to concentrate moth feeding damage during outbreak years. Using a mark and recapture technique, the study showed that a relatively small proportion (4.5 %) of moths tended to revisit the same orchard. The moths strongly preferred damaged fruit (85 %) over undamaged fruit. Visible damage (rotting symptoms) typically became apparent within 3 to 5 days. Satsumas had a higher number of feeding scars (2.1) than Clementines (1.08), highlighting their susceptibility. The study also established that, on average, pierced soft citrus fruit takes about four days to display symptoms of decay. Synthetic proprietary Australian lures were ineffective at attracting the moth, whereas fresh bananas proved to be a successful lure. Furthermore, the addition of both Agar and Super absorbent polymer showed promise as thickening agents to enhance the longevity of fresh bananas in traps. The effectiveness of various trap designs was compared, including the funnel trap, delta trap, bucket trap, and circular trap, in capturing fruit-feeding moths. The funnel trap performed best as it captured the most moths, followed by the delta trap, Lynfield trap and disc trap, respectively. Additionally, an electronic enhancement to the funnel trap, incorporating a zapper element, improved efficiency. However, efforts to exploit both visual and olfactory cues through the inclusion of an Ultraviolet (UV) light component did not improve its effectiveness. No extensive outbreaks were recorded during the study; however, population variations of S. partita populations were recorded. Annual trends showed two population peaks, with the first peak recorded from December to March, while the second peak was recorded from April to July. The activity of the moths also differed across different months, with the highest peaks recorded in May, while no moths were recorded from August to November. Both cultivar type and farm location did not influence the occurrence of the moth. Meanwhile cumulative weather parameters (rainfall, temperature and humidity) from the four months prior to occurrence influenced the activity of S. partita. Temperature determined the timing of the outbreak, while rainfall determined the magnitude of the outbreak. Damage assessment showed very low fruit damage by S. partita throughout the monitoring period. Varying levels of infestation by a tachinid fly, 4 % and 35 %, were recorded for 2021 and 2022, respectively. The tachinid parasitoid could not be identified at the species level. A novel baculovirus, tentatively classified as S. partita NPV (SepaNPV), was identified as the larval mortality causative agent. This study enhanced our understanding of S. partita's biology and population dynamics, providing valuable insights for developing effective management strategies against this economically impactful citrus pest. Future research should focus on refining control measures and addressing the challenges of the adult moth's elusive nature. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
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- Date Issued: 2024-10-11
The androgenic and anabolic effects of pine pollen on Nile tilapia (Oreochromis niloticus)
- Authors: Abaho, Ivan
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431615 , vital:72790
- Description: Access restricted. Expected release date in 2025 , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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- Date Issued: 2023-10-13
Effect of environmental responsible behaviour intervention programme on secondary school learners in environmental education knowledge, attitudes and practices in Nigeria
- Authors: Olagbaju, Oluwaseun Olaitan
- Date: 2021-09
- Subjects: Environmental education , Education, Secondary
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20284 , vital:45647
- Description: The depletion of the environment compelled researchers to investigate Environmental Education issues, the methods of imparting knowledge and the creation of awareness about environmental problems. However, youths have knowledge of environmental concepts but lack the skills, intentions, and action competence to exhibit positive environmentally responsible behaviour. There is, therefore, a need for a change in human behaviour to overcome current environmental problems. This study determines the effect of an environmental responsible behaviour intervention programme on Junior Secondary School learners in environmental education. It also explores the moderating effects of gender and school location. The study adopted a pre-test, post-test, control group and quasi-experimental design. A multi-stage sampling technique was employed. Eight (8) coeducational secondary schools in Ibadan, Nigeria, were selected based on environmental challenges in their immediate environment. There were four (4) schools from Ibadan city (urban area of Ibadan) and four (4) from Ibadan less city (rural area of Ibadan). Seven hypotheses were tested at a 0.05 level of significance. Five research instruments were used for this study. Analysis of Covariance (ANCOVA) was used in testing the seven formulated hypotheses. Estimated Marginal mean analysis was used to determine the source of significant effect of treatment. A significant interaction effect was described using a graphical representation. All hypotheses were tested at P< .05 level of significance. The result reveals that there was a significant main effect of treatment (Environmental responsible behaviour intervention programme on Junior Secondary School learners’ environmental knowledge (F(1,715) = 40.62, p < 0.05, Partial , 2 .054). There was also significant main effect of treatment (environmental responsible behaviour intervention programme on junior secondary school students’ environmental attitude. (F(1,715) = 32.36, p < 0.05. partial 2 = 0.043). The effect of treatment (Environmental responsible behaviour intervention programme) on students’ environmental practices was statistically significant, F(1,715) = 17.02, p < 0.05. partial 2 = 0.023). The findings shows that there was a significant main effect of school location (Urban and Rural) on Junior Secondary School students’ environmental knowledge (F(1,716) = 71.62 p< 0.05. partial 2 =0.091). There was no significant main effect of gender (male / female) F(1,715) =0.27, p> 0.05, partial 2 = 0.000. The findings further shows that there was significant main effect of school location on students’ environmental attitude, (F(1,175) =39.21, p< 0.05 partial 2 = 0.052) Shows that there was no significant main effect of gender on students’ environmental attitude F(1,715) =2.1, p> 0.05. partial 2 =0.003 There was significant main effect of school location on students’ environmental practices, F(1,715) = 17.02, p< 0.05 partial 2 = 0.019 but there was no significant main effect of gender on students’ environmental practices, (F(1,715) = 1.17, p> 0.05. partial 2 = 0.002). Based on these findings, it is recommended that teachers should use an environmental responsible behaviour intervention programme in teaching environmental concepts in the classroom. To support this, group/teamwork should be encouraged amongst students. Students should be allowed to construct knowledge in order to bring about their active participation with a view to making learning realistic and effective and to enable the exhibition of environmentally friendly behaviour. , Thesis (PhD)(Education)-- University of Fort Hare, 2021
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- Date Issued: 2021-09