Spatial and seasonal distribution of selected persistent organic pollutants and phenolic derivatives along the course of the Buffalo River in the Eastern Cape Province of South Africa
- Authors: Yahaya, Abdulrazaq
- Date: 2017
- Subjects: Organic water pollutants Water -- Purification -- Organic compounds removal
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/5939 , vital:29448
- Description:
Persistent organic pollutants (POPs) fall under a group of synthetic chemicals known for their persistence in environmental matrices such as soil and water, and are used in industrial, domestic and agricultural applications. Because of their volatility and lipophilicity, POPs can be transported far away from their point sources and bio-accumulate in food and in fatty tissues of humans and animals. In view of their toxicity and carcinogenicity some organic pollutants such as polychlorinated biphenyl (PCBs), organochlorine pesticides (OCPs) and phenolic derivatives (chlorophenol and nitrophenol) have been classified by United State Environmental Protection Agency (USEPA) and World Health Organization (WHO) as priority pollutants. The present work evaluated the distribution patterns of 19 polychlorinated biphenyls congeners, 17 organochlorine pesticides and selected phenolic derivatives (USEPA 11-priority pollutants) in the Buffalo River, in the Eastern Cape Province, South Africa between December 2015 and May 2016. The Liquid-liquid extraction technique was used for PCBs, OCPs and phenolic derivatives in the river water samples. Silica gel and florisil clean up were carried out for PCBs and OCPs samples respectively and analyzed with gas chromatography electron capture detector (GC/ECD). Phenolic compounds were derivatized and analyzed by gas chromatography mass spectrometer (GC/MS). Limits of detection (LOD), limit of quantitation (LOQ) and relative standard deviation (RSD) for the PCBs were 10 to 330 ng/L, 20 to 1,060 ng/L and 1.18 to 14.1 percent respectively. The LOD, LOQ and RSD for the OCPs were from 20 - 60 ng/L, 110 - 530 ng/L and 0.02 - 0.06 percent, while the corresponding values for the phenolic derivatives were 10 to 70 ng/L, 33 to 222 ng/L and 1.99 - 10.86 percent. In summer, the concentrations of PCBs, OCPs and phenolic derivatives ranged from
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Statistical analysis and modelling of malaria relapse risk factors using Cox Proportional Hazards model approach : a case study of material data collected from Democratic Republic of Congo
- Authors: Mutambayi, Ruffin Mpiana
- Date: 2017
- Subjects: Malaria -- Congo (Democratic Republic) -- Mathematical models Statistics -- Congo (Democratic Republic) -- Econometric models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15001 , vital:40110
- Description: The field of survival analysis has experienced tremendous growth during the latter half of the 20th century. The objective of this study was to model the relapsing time of uncomplicated falciparum malaria using biographical, sanitation, environmental and preventive information as covariate risk factors. The methodological developments of survival analysis that have had the most profound impact are the Kaplan-Meier method for estimating the survival function, the log-rank test for comparing the equality of two or more survival distributions, and the Cox proportional hazards (PH) model for examining the covariate effects on the hazard function. This thesis presents basic concepts, nonparametric methods (the Kaplan-Meier method and the log-rank test), semi parametric methods (the Cox PH model, and Cox model with time-dependent covariates) and parametric methods (Parametric PH model and the AFT model) for analysing survival data. An improved method was applied to randomized uncomplicated falciparum malaria patients to investigate the risk factors related to the relapsing time in RD Congo. Firstly, the Cox PH model , inf 1 0 ( ) ( )exp 1.91613 0.49633 0.81466 dump spr t X h h t X X X where is the instantaneous risk of experiencing the event at time , without the influence of any covariate was found to better fit the data, as confirmed by the results of the global test that present reasonable and significant results: (Likelihood Ratio: 18.2264 with p-value < 0.0004; Score: 17.6569 with p-value < 0.0005 and Wald: 19.3975 with p<0.0002). Hence from the model above, it can be noticed that ‘dumping site’ (p-value <0.0106; 95percent HR C.I: 1.545, 29.451), ‘spray used’ (p-value < 0. 0.0220; 95percent C.I: 0.391, 0.915), and ‘information related to source of malaria’ (p-value < 0. 0.0012; 95percent C.I: 1.380, 3.725), have a significant impact on the relapsing time of the patients under investigation. It should be noted that many 0() h tt other important covariates such as “usage of mosquito nets” were excluded because of the non-proportionality of the hazards. Secondly, the improvement concept was applied to the Cox model as proposed, and the improved model was as follows: h h t t X t X t X t X t X t X t X t r dump_inf1 spr_inf1 Where h0 (t) is the instantaneous risk of experiencing the event at time t , without the influence of any covariate. The model was found to better fit the data than the standard model — as confirmed by the results from the convergence criterion comparison, where the AIC value of the improved model (754.460) was lower than that of the standard model (767.428). Moreover, the improved model was found to be adequate as the results from the global null hypothesis were significant: (Likelihood Ratio: p-value is 0.0001; Score: p-value is 0.0001; Wald: p-value is 0.0001) and the goodness-of-fit test was confirmed by the plotting of Coxresiduals where the 45 degrees’ line confirmed the results. In conclusion, it was found that the covariates ‘pit’ (p-value is 0.0009; 95percent HR C.I: 11.4133, 1.243e+04), ‘tdwel_spr’ (pvalue = 0.0257; 95percent HR C.I: 1.0016, 1.030e+00), ‘tdwel_inf1 (p-value = 0.0122; 95percent HR C.I: 0.9691, 9.964e-01), ‘maint_dump’ (p-value is 0.0005; 95percent HR C.I: 1.0239, 1.087e+00),‘maint_pit’ (p-value is 0.0007; 95percent HR C.I: 0.9179, 9.774e-01), ‘dump_spr’ (p-value is 0.0027; 95percent HR C.I: 0.9308, 9.853e-01), ‘dump_inf1’ (p-value <0.0001; 95percent HR C.I: 0.9849, 9.947e-01) and ‘spr_inf1’ (p-value is 0.0005; 95percent HR C.I: 1.0119, 1.043e+00) affected the time to relapse from uncomplicated falciparum malaria.
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The effects of Real Exchange Rate (RER) on the export competitiveness of South African fruit industry
- Authors: Peter, Bathathu
- Date: 2017
- Subjects: Foreign exchange rates -- South Africa Free trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15732 , vital:40514
- Description: South Africa has diverse climatic conditions that allow it to grow and produce various fruit cultivars across the country. Limpopo, Western Cape, Mpumalanga, Eastern Cape, KwaZulu-Natal, and Northern Cape are South Africa’s main fruit production regions. In 2015, fruits ranked the 7th largest sector on exports and the largest in South Africa’s agricultural exports. South Africa’s major export partners for fruit in the same year were Netherlands, United Kingdom, Russian Federation, United Arab Emirate, and Hong Kong China. Correspondingly, exports to non-traditional markets such as India and China have increased rapidly. South Africa has prioritized exports as the engine for economic growth and job creation. The country has two major export destinations namely; the high income countries of Europe and North America, and the low-income markets of Africa, especially Southern African Customs Union (SADC) countries. South Africa’s Real Exchange Rates (RER) fluctuated widely since early 1970’s. This occurred after the collapse of the Bretton Woods system of fixed exchange rates in 1973. South Africa’s RER has been depreciating since then. Consequently, there has been a proliferation of debates on the relationship between the RER and exports performance. The most commonly held belief is that the RER depresses trade thereby increasing riskiness of trading activity. The South African fruit industry has been operating in the background of the depreciating RER. A high degree of RER volatility has posed a serious challenge to policy making environment because the magnitude of its impacts on trade flows is still unknown. The policy making environment becomes stagnant. Policy makers and researchers continue to examine the effects of RER on trade for an indefinite period. The South African fruit producers are unable to anticipate income earnings from trade due to increased risks associated with RER. South Africa’s agricultural sector encompasses the Historically Disadvantaged Individuals (HDI) which the country wants to prioritise and give them opportunities to participate in trade. The risks associated with the RER impair the development of the HDIs. The Thesis seeks to examine South Africa’s trade performance and the competitiveness of South African fruit industry as well as the effects of the RER. Specifically, the Thesis examines South Africa’s global fruit trade performance, explores the export competitiveness of South African fruit industry, and estimates the export demand equation for South African fruit exports to the world. The Thesis used the data obtained from the Department of Agriculture, Forestry and Fisheries (DAFF) for the period of 1080 to 2015 to estimate the export demand equation. The data from the International Trade Centre (ITC) for the period of 2001 to 2015 was used to examine South Africa’s global trade performance and competitiveness. The analytical framework followed incorporates the South Africa’s fruit Trade Performance Index (TPI) and the effects of RER on South African fruit industry. The TPI presents South Africa’s global fruit trade and its competitiveness using Trade Map, while the effects of RER are investigated on local fruit sales and on exports using the regression model. The Trade Map is the dominant trade analysis tool increasingly being used by the researchers and policy makers to make informed decisions on trade issues. The Thesis also made use of the Trade Map tools to examine South Africa’s global fruit trade performance and its competitiveness. The market analysis tools developed by the International Trade Centre (ITC) are: Trade Map, Market Access Map, Investment Map, Trade Competitiveness Map, Standard Map, and the Procurement Map. Trade Map, Trade Competitiveness Map, and the Market Access Map are used. Subsequently, the Thesis applied econometric techniques to examine the effects of RER on South Africa’s fruit exports and on fruit sales on local markets using the regression model. In this regard, the Thesis followed the export demand equation used by Todani and Munyama (2005). De Vita & Abbott (2004), and Tandra-Ragoobur & Emamdy (2011). Todani & Munyama (2005), to estimate the relationship between exchange rate volatility and South African export. Real exports and the exchange rate volatility were the main variables used in the model. The relative prices and the income of South Africa’s trading partner were also included in the model. The results show that South Africa was the 11th largest fruit exporter after Viet Nam and Spain in 2015. During the same year, the U.S. was the largest exporter of fruit with 14percent in the world, followed by Spain and Netherlands with 9percent and 6percent, respectively. The fruit industry ranked 8th largest exporter and the largest in agricultural sectors in 2015. Its exports totaled R 37 133 million in 2015, from R 30 566 million in 2014. South Africa’s total fruit exports accounted for a 33percent share on total agricultural exports and 4percent on South Africa’s total exports in 2015. The coefficients of the regression model were all statistically significant. Most importantly, an inverse relationship between the relative price and South Africa’s real fruit exports was established. Moreover, the RER had a significant negative effect on the South Africa’s fruit export competitiveness. This imposes more pain on the development of the HDIs in South Africa’s agricultural sector. South Africa has desire to move away from the export of raw materials and traditional export commodities and promote the export of value added products, including the agro processing products. Accordingly, this affects the entire value chain of the agricultural sector, since trade cannot be anticipated. On the basis of the regression results shown by the variables included in the model, the objectives of the study were accomplished. South Africa’s fruit exports are said to be more competitive to the European markets as a result of the weaker rand relative to other countries. The overview of South Africa’s fruit trade shows that South African fruit exports are more competitive across the globe. This is probably because the South Africa’s fruit exports for the top ten commodities are ranked almost the first five in the European markets and the first ten for the world. The results are supported by previous documented research, which emphasised that the weaker rand leads to more South African fruit produce being absorbed by the international markets. The evidence from the results shows that the RER stimulates the fruit export competitiveness.
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Environmental management in military activities of the South African National Defence Force
- Authors: Magagula, Hezekiel Bheki
- Date: 2016
- Subjects: South Africa -- South African Defence Force Military bases -- Environmental aspects Hazardous waste site remediation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/5927 , vital:29430
- Description: This thesis presents research findings on current environmental management practices used by the South African National Defence Force (SANDF). Two case studies are presented; the first is the Grahamstown Military Installation (6 South African Infantry Battalion) and the second the South African Army Combat Training Centre (42 Brigade). A combination of three sampling techniques, namely, the stratified, purposive and link-tracing (snowball) samplings were employed and structured questionnaires and semi-structured interviews with key SANDF officials were used as primary data. In addition, secondary data sources in the form of inter alia the first and second editions of the Environmental Management Plan for Defence (2001 & 2008 respectively); the development and implementation of environmental education and training in the military: a joint United States-Republic of South Africa Environmental Working Group Project (2003); Overarching Strategic Statement for 2011; Integrated Environmental Management Information Series: Linking Environmental Impact Assessment and Environmental Management Systems (2004); The Department of Defence Strategic Plan (2010): Republic of South Africa and the South African Defence Review (2012) were studied. In addition, field observations were also carried out within the two military installations training areas between July, 2011 and November, 2013. Primary data on the conditions of training areas, waste removal after training exercises, pollution prevention measures, and rehabilitation efforts to restore degraded training ranges were collected. Furthermore, composite surface sediment samples and water samples were collected for analysis. A total of fifty-six surface sediments and thirty water samples were analysed for the concentrations of heavy metals using the ICP-MS. These attitudes and perceptions are predominantly positive. Statistical analysis (ANOVA) did not reveal any significant differences in responses, especially, between military ranks. However, sporadic significant differences were found in five of the statements in the questionnaire from respondents with different service periods. Furthermore, the emphasis placed on environmental protection within defence force activities worldwide has compelled the South African Department of Defence and Military Veterans (DoDMV) to regulate the management of the environment within its properties. Yet, these efforts have faced numerous challenges ranging from financial to human resource deficiencies. It was found that environmental management practices and programmes at different military installations vary significantly. Consequently, six environmental management programmes were identified at South African Army Combat Training Centre, while only one environmental management programme was identified at Grahamstown Military Installation. This programme is a collaborative effort between the SANDF/DoDMV and the Department of Water Affairs and Sanitation to eradicate invasive alien plant species. In the light of the analysis of official documents and interviews with respondents, it was established that the DoDMV does not have a budget for environmental management services and environmental management is yet to be incorporated into formal military training programmes. There is a severe shortage of environmentally qualified and knowledgeable personnel within the SANDF. Subsequently, all these drawbacks lead to the failure of the implementation of the Defence Force’s Environmental Management System (EMS) and inadequate management of the environment at military installations of the SANDF. Consequently, these challenges have severely compromised the commitment of the SANDF to honour its environmental management obligations. Such deficiencies tend to undermine the sustainable utilisation of the national assets entrusted to the Defence Force. Therefore, this thesis argues that environmental management programmes for the SANDF are based on a very weak foundation. This thesis proposes an ideal model for the successful implementation of the EMS and management of the environment at SANDF military installations. The analysis of water and soil samples led to the identification and quantification of heavy mental pollutants. The concentrations of heavy metals in water samples were varying between <0.01 to <0.05mg/l, but generally constant. Thus, no significant or meaningful statistical results were obtained. Pearson’s correlation coefficient was used to analyse the concentrations of heavy metals obtained in the sediment samples.
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Molecular characterization of Mycobacterium bovis isolated from cattle and sputum specimens from humans in the Eastern Cape province, South Africa : public health and economic implication
- Authors: Bhembe, Nolwazi Londiwe
- Date: 2016
- Subjects: Mycobacterium tuberculosis -- South Africa -- Eastern Cape Public health -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/13238 , vital:39625
- Description: Tuberculosis (TB) is a disease caused by the members of the Mycobacterium tuberculosis complex (MTBC), which infects both animals and humans. The primary host of Mycobacterium bovis is cattle. It remains a major global health problem. About 2 billion people are thought to be infected with TB and about 1.3 million decease each year from the disease. This study is aimed at determining the prevalence of the disease, characterizing the MTBC isolates and increasing the understanding of the genetic diversity MTBC in the Eastern Cape Province of South Africa, from studying both samples from both humans and cattle. A total of 376 cattle lymph nodes were collected from two commercial abattoirs for investigations. Suspected 6 000 sputum specimens were also collected from humans (cattle farmers). All collected samples were cultured, and isolates were confirmed with a multiplex polymerase chain reaction (PCR) targeting the mpb64 and IS6110 genes. Positive isolates were tested for resistance against anti-TB drugs using the standard Lowenstein Jensen proportion method. Isolates from cattle lymph nodes were further characterized to species level, using the region of deletion 1 (RD1) and oxyR restriction fragment length polymorphism analyses. MIRU-VNTR typing and spoligotyping assays were used to further examine the genetic diversity of all strains. Obtained spoligotype patterns were matched with isolates published in the universal spoligotyping database (SITVIT2). MTBC was detected in 162 (43.09 percent) cattle lymph nodes and 156 sputum specimens. Some isolates 25.9 percent (42/162) from the cattle lymph nodes samples were resistant to rifampicin (RIF) and 98.7 percent (154/156) were resistant to isoniazid (INH) and rifampicin (RIF) (of the human sputum specimens). All cattle lymph nodes isolates exhibited the RD1 gene, and the oxyR analyses classified 96.9 percent of the isolates as Mycobacterium tuberculosis complex and 3.1 percent as Mycobacterium bovis. Twenty seven spoligotype patterns were isolated from cattle lymph nodes, with 10 shared types (SIT) consigned to 5 lineages, including Bov_4-Caprea (1.9 percent), Microti (0.6 percent) and Beijing (17.9 percent) constituting East Asian, Latin-American-Mediterranean (LAM) (3.7 percent), X (4.3 percent), MANU (3.1percent), S (0.6 percent) and 67.9 percent were orphans that were further categorized to their designated lineages (Indo-Oceanic, Euro-American and West-African 2). Ninety one percent of the isolates from humans (farmers) were grouped into 7 clusters by spoligotyping, while the remaining 9 percent was unclustered. SITs were observed in 89.6 percent of the isolates from the Beijing, LAM, X, T and S families. The Beijing family was the most prevalent strain from both human isolates (77.2 percent) and cattle lymph nodes isolates (17.9 percent), and the T (0.6 percent) and Microti (0.6 percent) families were the least detected genotypes in both humans and cattle lymph nodes. In the cattle lymph nodes, spoligotyping showed a higher clustering rate of 82.1 percent, with the lowest (HGDI) = 0.485. The 12 MIRU-VNTR clustering rate was 64.8 percent, showing a higher HGDI of 0.671. However, a combination of both methods showed a decreased clustering rate of 53.7 percent; however these methods resulted in a higher HGDI (0.676). Isolates from human sputum specimens spoligotyping showed a higher clustering rate of 89 percent with an HGDI = 0.822. The 12 MIRU-VNTR showed the lowest clustering rate of 69 percent and an HGDI = 0.940 and the combination of the methods showed a clustering rate of 78 percent and an HGDI = 0.951. The results of this study show the diversity of MTBC strains in the Eastern Cape Province and the low clustering rate indicates continuing transmission in the province. The detection of MTBC strains from slaughtered cattle lymph nodes in abattoirs confirms the risk of providing TB infected meat in markets which has serious implications for the control of TB in South Africa. The continuing spread of MTBC in South Africa threatens both the public and economic health.
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Moringa oleifera leaf powder as a functional antioxidant additive in pork droewors
- Authors: Mukumbo, Felicitas Esnart
- Date: 2016
- Subjects: Antioxidants , Moringa oleifera , Pork -- Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15354 , vital:40400
- Description: The study investigated the effect of Moringa oleifera leaf powder (MLP) on physico-chemical characteristics, antioxidant activity, antioxidant compound content and lipid oxidation in pork droëwors. Firstly, the physico-chemical properties (proximate composition, salt content, water activity (aw), pH) of commercially produced droëwors from different types of meat (beef, game, ostrich) were determined. In the second experiment beef and pork droëwors with similar fat content were produced. Physico-chemical properties and lipid oxidation (thiobarbituric reactive substances (TBARS)) during processing and 26 days of storage at 25 °C and 50percent relative humidity (RH) were measured. In the third experiment, antioxidant compounds (Total Phenolic Compounds (TPC), α-tocopherol, β-carotene) in MLP were quantified. Thereafter, 4 treatments of pork droëwors were produced, with MLP included at 0, 0.5, 1 and 2 g/ 100 g. Physico-chemical properties and TBARS were measured at intervals during drying (0, 1.5, 5.75, 27.25, 72 h) and after 7 days of storage under ambient conditions. Antioxidant activity (ferric reducing antioxidant power (FRAP)), TBARS, α- and γ-tocopherol, and β-carotene contents were measured. In the fourth experiment, three batches of droëwors were produced (C: no antioxidant, M0.75: 0.75 g/ 100 g MLP, VE: 15 mg/ kg α-tocopherol oil) and stored at 25 °C and 50percent relative humidity for 112 days. Drying kinetics and α-tocopherol contents of pork droëwors after drying were measured and the physico-chemical properties and TBARS were followed during storage. Results showed no differences (P > 0.05) in the physico-chemical characteristics of beef, game meat and ostrich droëwors; containing on average 25.8 ± 1.25 g/100 g moisture, 42.0 ± 0.10 g/100 g protein, 32.0 ± 1.68 g/100 g fat, 6.2 ± 0.13 g/100 g ash and 4.2 ± 0.10 g/100 g salt; with aw and pH of 0.79 ± 0.015 and 5.3 ± 0.05, respectively. During processing and storage, TBARS were higher (P < 0.05) in pork droëwors (maximum 3.83 mg MDA/kg DM) than in beef (maximum 0.99 mg MDA/kg DM). Moringa oleifera leaf powder contained high levels of TPC (7.5 ± 0.2 mg gallic acid eq/g) and substantial levels of α-tocopherol (76.7 ± 1.9 mg/100 g) and β-carotene (23.2 ± 2.8 mg/100 g). The FRAP, α-tocopherol and β-carotene content of pork droëwors increased (P < 0.05) proportionally with increasing levels of MLP inclusion. Lipid oxidation occurred more rapidly (P < 0.05) when MLP was not added and was similar (P > 0.05) for all MLP treatments. There was no significant effect of the inclusion of 0.75 g/100 g MLP on the drying curves and physico-chemical characteristics of the droëwors. The α-tocopherol content was higher (P < 0.05) and TBARS during storage were lower (P > 0.05) with MLP addition. The results of the current study give an overview of the composition of commercial droëwors and showed higher susceptibility to lipid oxidation in pork droëwors. Moringa oleifera leaf powder exhibited antioxidant activity in pork droëwors, inhibited lipid oxidation and increased the content of α-tocopherol in the product. It can be concluded that MLP could be used as a functional antioxidant additive in pork droëwors.
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Synthesis and characterization of group 12 dithiolate complexes as single source precursors for the preparation of hexadecylamine capped metal sulfide nanoparticles and polymer
- Authors: Osuntokun, Jejenija
- Date: 2016
- Subjects: Nanotechnology Nanoparticles Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/14060 , vital:39801
- Description: A series of heteroleptic mixed ligand complexes of some alkyl substituted thiourea, tetramethyl thiuram disulfide and 1-cyano-1-carboethoxy-2,2 ditholate of Zn(II) Cd(II) and Hg(II) have been synthesized by stoichiometry reactions of the ligands with respective metal salts. They have been characterized with analytical and spectroscopic techniques. Seven out of the 19 complexes synthesized are pyridine 2, 2 bipyridine and 1, 10 phenanthroline adducts of dissopropyl parent adducts of Zn(II) and Cd(II) complexes. All the complexes are proposed as four coordinate except the pyridine adducts, 2, 2’ bipyridine and 1, 10 phenanhroline adducts that are proposed as five and six coordinate respectively. All the complexes are solid, air stable and moisture stable for a many months. They are not soluble in common organic solvents but partially soluble in coordinating solvents like DMF and DMSO and due to their insolubility problems all attempts to grow single crystal of the complexes proved abortive. The complexes gave respective metal sulfide on thermal decomposition in TGA and this makes them to be potentially useful single source precursor for the synthesis of metal sulfide. All the complexes were invariably thermolysed in HDA to synthesis a series of HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles reveal that they are all blue-shifted from the absorbance edge and this confirms quantum confinement of the nanoparticles. The transmittance electron microscope showed that the nanoparticles are in nanodimension. ZnS nanoparticles from the pyridine adducts gave HDA-capped ZnS nanoparticles with a mixture of hexagonal and cubic phases while the HDA capped CdS from the 2, 2 bipyridine and 1,10 phenanthroline gave anisotropic nanoparticles. The sizes of the CdS from the 1,10 phenanthroline adducts were also found to be biggest while CdS nanoparticles from 2,2 bipyridine adduct were also revealed to be bigger than the particle sizes obtained from the parent complex, (1-cyano-1 carboethoxyethylene-2,2-dithiolato- κ,S’S)-bis(N, N’-diisopropylthiourea -κS)cadmium(II). ZnS and CdS polymer encapsulated nanocomposites were also synthesized using a solution casting method. The polymers employed were; Polymethyl metharcrylate (PMMA), Poly(vinly alcohol) (PVA), and poly vinyl pyrrolidone (PVP). The structural and thermal properties of the pure polymers and the respective nanocomposites were investigated. It was observed that the ZnS/PVA and CdS/PVA were the most thermally stable composites when the thermal stability of the pure polymers were compared relative to the nanocomposites using data obtained from thermal decomposition results of the TGA.
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Improving Productivity of Maize-based Smallholder Irrigated Cropping Systems: A Case Study of Zanyokwe Irrigation Scheme, Eastern Cape, South Africa
- Authors: Fanadzo, Morris
- Date: 2010
- Subjects: Farms, Small -- South Africa -- Eastern Cape Crop yields -- South Africa -- Eastern Cape Agricultural productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/11009 , vital:36450
- Description: Smallholder irrigation schemes (SIS) in South Africa have performed poorly and failed to achieve the development objectives of sustaining rural livelihoods by increasing crop production and income. Limited knowledge of crop production among farmers is one constraint to improved crop productivity and, yet little research has been carried out to relate agronomic practices to productivity. This study was aimed at identifying strategies to improve the productivity of maize-based smallholder irrigated cropping systems in South Africa, using Zanyokwe irrigation scheme (ZIS) in the Eastern Cape Province as a case study. The research design was emergent, developed progressively as influenced by the progressive analyses that were made. The research work involved two main phases: exploratory studies and refinement on-farm experiments for testing technologies as informed by the exploratory studies. Exploratory studies were aimed at describing farmer crop production practices in major crop enterprises and identifying and prioritizing major agronomic yield constraints. Findings indicated that the overall performance of the cropping systems was poor as evidenced by low overall yields of < 25% of the potential in maize and butternut. Poor management of weeds, soil fertility, plant populations and water, late planting and poor cultivar choice were the most important yield constraints. The average cropping intensity achieved by farmers was only 48%. New hybrids yielded 50 - 65% higher grain than the cultivars commonly grown by farmers. However, farmers favoured their traditional cultivars, as they preferred green maize production as opposed to dry grains. As a result of these findings, focused research was designed on options for iii improving green maize production, soil fertility, crop stand and weed management in crop production. On-farm trials were, therefore, designed to (1) compare the response to nitrogen (N) rate of direct seeded and transplanted maize; (2) evaluate comparative performance of direct seeded and transplanted green maize under farmer management, and to work out the economics of transplanting; (3) investigate the effects of row spacing and atrazine dosage on weed dynamics maize yield; (4) determine the effects of inter-row spacing and plant population on weed dynamics and maize yield; and (5) investigate the effects of pre-plant weed control, N rate and plant population on weed dynamics and butternut yield. Maize transplanting improved crop stand, had earlier maturity and yielded higher at lower N rates compared to direct seeding for both green and grain maize. Total costs that varied were higher by R3 565 ha-1 for transplanted maize compared to direct-seeded maize, but the net benefits from transplanting were also much higher by R8 773 ha-1. Farmers favoured transplanting, citing bigger cobs, early maturity and the absence of seedling damage by birds, when maize was transplanted. However, a follow-up survey conducted during the subsequent year indicated that five of the six farmers abandoned transplanting, citing shortage of labour and high cost of commercially produced seedlings. It was concluded that transplanting is unlikely to be adopted unless the labour intensiveness of manual transplanting can be solved. Increasing atrazine dosage from a third of the label recommended dosage (LRD) and reducing row spacing from 90 to 45 cm resulted in an increase in weed mortality. A 100% kill of annual broadleaf weeds was possible while iv perennial grasses and the annual broadleaf weed, Oxalis latifolia, could not be controlled even at the LRD. However, improved weed mortality with increase in atrazine dosage and/or narrow rows did not translate into improved maize productivity. In butternut, pre-plant weed control resulted in a six-fold decrease in weed biomass and a 100% increase in fruit yield. These findings demonstrated the possibility of incorporation of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on maize yields in smallholder farming systems. The results also suggested that pre-plant weed control is one of the pre-requisite to successful butternut production in SIS in South Africa. Increasing maize population from 40 000 to 60 000 plants ha-1 resulted in a 30% grain yield increase, but decreased length of cobs. Row spacing had no effect on maize yield at 40 000 plants ha-1, but at 60 000 plants ha-1 45 cm rows resulted in 11% higher grain yield (12 547 kg ha-1) than 90 cm rows (11 288 kg ha-1). Butternut yield increased significantly (p < 0.01) with increase in plant population and N rate. The optimum butternut population and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. Pre-plant weed control in butternut resulted in a six-fold decrease in weed biomass. Increasing butternut planting density from 10 000 to 30 000 plants ha-1 decreased weed biomass by 47%. No marketable fruits were obtained when planting was done without prior weed control. This result suggest that application of non-selective herbicide before planting is one technique that can be used by farmers as part of integrated weed management to give the crop a competitive advantage in the early growth stages before the plants start to produce vines. Yield increased significantly (p < 0.01) with increase in plant density and N rate. The optimum plant density and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. These findings emphasise the need to take into consideration production practices by farmers as a basis to build up skills in the management of crop enterprises and the farm as a viable business in any efforts to improve on the performance of SIS in South Africa. Future research should concentrate on labour-saving sustainable production technologies for SIS in South Africa.
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Prevalence of Listeria pathogens in effluents of some wastewater treatment facilities in the Eastern Cape Province of South Africa
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape Sewage -- Purification -- South Africa -- Eastern Cape Water -- Pollution -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7826 , vital:30747
- Description: astewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community.
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