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Photocatalytic activity and antibacterial properties of Ag/N-doped TiO2 nanoparticles on PVAE-CS nanofibre support
- Authors: Ocwelwang, Atsile Rosy
- Date: 2012
- Subjects: Nanocomposites (Materials) , Nanofibers , Electrospinning
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11337 , http://hdl.handle.net/10353/d1006794 , Nanocomposites (Materials) , Nanofibers , Electrospinning
- Description: Lack of potable water is one of the major challenges that the world faces currently and the effects of this are mainly experienced by people in developing countries. This has therefore propelled research in advanced oxidation technologies AOTs to improve the current water treatment methods using cost effective, non toxic and efficient treatment methods. Hence, in this study the sol-gel synthesis method was used to prepare TiO2 nanoparticles that were photocatalytically active under UV and visible solar light as well as possessing antibacterial properties. Silver and nitrogen doping was carried out to extend the optical absorption of TiO2. For easy removal and reuse of the photocatalyst the nanoparticles were immobilized on chitosan and poly (vinyl-alcohol-co-ethylene) using the electrospining technique. The synthesized nanomaterials were characterized by FTIR, XRD, SEM/EDS, TEM, DRS, and TGA. FTIR and EDS analysis confirmed the formation and composition of TiO2 nanopowders for the doped and undoped nanoparticles. XRD analysis showed that the anatase phase was the dominant crystalline phase of the synthesized nanopowders. SEM and TEM respectively illustrated the distribution and size of the electrospun nanofibers and the nanoparticles of TiO2. DRS results showed that there was a significant shift in the absorption band edge and wavelength of Ag-TiO2 to 397 nm, followed by N-TiO2 at 396 nm compared to the commercial titania which was at 359 nm. The photocatalytic activities and antibacterial properties of these materials were tested on methylene blue dye and E.coli microorganism respectively. Ag-TiO2 immobilized on nanofibers of chitosan and PVAE had the highest photocatalytic activity compared to N-TiO2. Similar results were observed when the biocide properties of these materials were tested on E. coli.
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Environmental Chemistry: PAC 326
- Authors: Vala, M K , Katwire, D M , Purcell, W
- Date: 2011-01
- Language: English
- Type: Examination paper
- Identifier: vital:17817 , http://hdl.handle.net/10353/d1010370
- Description: Environmental Chemistry: PAC 326, supplementary examination January 2011.
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Cattle manure, scalping and soil wetness effects on some physical properties of a hardsetting soil and associated early maize growth
- Authors: Nciizah, Adornis Dakarai
- Date: 2011
- Subjects: Soil formation , Crops and soils , Manures , Soil mechanics , Soil moisture , Soil stabilization , Soil penetration test
- Language: English
- Type: Thesis , Masters , MSc Agric (Crop Science)
- Identifier: vital:11861 , http://hdl.handle.net/10353/349 , Soil formation , Crops and soils , Manures , Soil mechanics , Soil moisture , Soil stabilization , Soil penetration test
- Description: Most soils in the Eastern Cape Province, South Africa are shallow and are low in organic matter. Therefore these soils are structurally fragile and highly susceptible to inherent degradative processes like hardsetting. The objective of this study was to determine the effect of cattle manure, scalping and soil wetness on aggregate stability, penetration resistance and early maize growth in hardsetting soils. Glasshouse and field studies were conducted to determine the effect of cattle manure on aggregate stability and penetration resistance of freshly exposed topsoils by scalping at 0, 10 and 20 cm depths. In the glasshouse cattle manure was applied at 0 and 20 Mg/ha and matric suction was kept at ~ 30 and ~ 400 kPa; contrasting high and low soil wetness. Three soils were put in pots and arranged in a randomized complete block 3 2 2 factorial design. The field study was done at the University of Fort Hare research farm and the treatments were arranged in a split-plot complete randomized design with three replications. Scalping treatment was the main plot whilst the quantity of the cattle manure applied was the sub plot. Cattle manure increased mean weight diameter (MWD) by between 48% and 71% under glasshouse and between 18% and 33% under field conditions, depending on the soil wetting rate. Cattle manure reduced MWD when the soil under field condition was subjected to mechanical shaking. Soil penetration resistance decreased linearly, with increasing soil wetness but it rapidly increased with increase in matric suction up to ~200 kPa and thereafter the rate of increase reduced. In the glasshouse, all treatments had no significant effects on shoot dry weight but low matric suction increased root dry weight by 133%. Interaction of cattle manure and low matric suction reduced shoot length by 6%, shoot fresh weight by 25%, root surface area by 36%, root length by 5% and root fresh weight by 29% compared to the control. In contrast, application of cattle manure and high matric suction increased shoot length by 37%, shoot fresh weight by 136%, root surface area by 159%, root length by 94% and root fresh weight by 119%. In the field, cattle manure application increased root length density and shoot dry matter by 26% and 30% respectively. Cattle manure improved the stability of aggregates of the hardsetting soil under rapid or slow water intake conditions experienced during rainfall or irrigation. However, under field conditions cattle manure acted as a deflocculant and decreased the stability of aggregates when mechanical stress was applied. The effectiveness of cattle manure in improving maize growth in hardsetting soils was determined by matric suction.
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Socio-economic benefits of agricultural projects to surrounding communities: the case of Qamata Irrigation Scheme in the Eastern Cape, South Africa
- Authors: Masela, Zandile
- Date: 2017
- Subjects: Agricultural development projects -- South Africa -- Eastern Cape , Agriculture -- Economic aspects -- South Africa -- Eastern Cape , Irrigation farming -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/4716 , vital:28501
- Description: The Qamata Irrigation Scheme (QIS) is one of the largest irrigation schemes in South Africa. Despite substantial state investment, community members have only derived limited benefits from the scheme, leading the government efforts to revitalize the scheme. Many studies have been conducted about QIS but none of them have analyzed the effects of the QIS on the surrounding communities. This study investigated the socio-economic benefits of QIS to surrounding communities. For the purposes of this study, the units of analysis were the surrounding household members, questionnaires were used to collect data. Probabilistic sampling of random sampling method was used to select the villages; respondents’ were availability selected with sample size of 197 households. Quantitative and qualitative data were collected from the participants. To analyse data, descriptive statistics and multinomial logit regression model were used. The study found out that female-headed households constitute 63.45 percent compared to male-headed households at 36.55 percent. The average age of the households in the villages that are within the radius of 10km is 58 years, while it is 59 years in villages that are beyond the 10km radius. In villages within the radius of 10km, 86.08 percent of respondents are unemployed, 5.70 percent are employed at the scheme and 8.23 percent are self-employed. In villages beyond 10km, 84.62 percent of respondents are unemployed, 5.13 percent are employed at the scheme and 10.26 percent are self-employed. In both villages, 71 percent of respondents reported that that they do not get feed supply from the scheme while 29 percent of respondents reported that they get feed supply from the scheme. From the overall distribution of villages within and beyond the radius of 10km, 80 percent of respondents reported that they do not get job opportunities from the QIS while 20 percent of respondents reported that they get job opportunities from the QIS. The study shows that 53 percent of respondents from villages within the radius of 10km are low-benefitting, 33 percent of respondents are intermediate-benefitting and 14 percent of respondents are high-benefitting from the scheme, while in villages beyond the radius of 10km, 97 percent of respondents are low-benefitting, 3 percent of respondents are intermediate-benefitting and none of the respondents is high-benefitting from the scheme. Furthermore, the study, through the multinomial logit regression model, shows that gender for intermediate benefitting has a negative coefficient (-1.70) and shows a significance of 10 percent On the other hand, gender for high benefitting has a positive coefficient (2.57) and shows a significance of 1 percent. Distance from the scheme has a negative coefficient (-3.08) and shows a significance of 1 percent. Access to farmland has a positive coefficient (2.33) and shows a significance of 10 percent. The study recommends that surrounding communities should own home gardens so that they can grow fresh produce and create job opportunities. The surrounding communities are also encouraged to own more farmlands or produce their own crops so they can also learn from the skills of the scheme.
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Agricultural production economics: AGE 222
- Authors: Tshuma, M C , Obi, A
- Date: 2010-01
- Subjects: Agricultural Production Economics
- Language: English
- Type: Examination paper
- Identifier: vital:17658 , http://hdl.handle.net/10353/d1010046
- Description: Agricultural production economics: AGE 222, supplementary examination January 2010.
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Modelling of the performance of a batch biogas digester fed with selected types of substrates
- Authors: Mukumba, Patrick
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc (Physics)
- Identifier: vital:11596 , http://hdl.handle.net/10353/d1016197
- Description: The increasing population and the rapid economic growth in South Africa have led to higher consumption of food resulting in the generation of large amounts of waste. In addition, South Africa has plenty of biomass from cattle, donkeys, horses, goats, pigs, chicken and sheep. However, anaerobic digestion could be an alternative solution for the utilization of these kinds of waste due to its environmental and economic benefits. Therefore, the main focus of the research was design, construct a field batch biogas digester, monitor its performance when fed with co-substrates and model the methane yield for an optimized mixing ratio.
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Principles of Irrigation: AGC 321
- Authors: Meikle, G. J , Chiduza, C
- Date: 2010-02
- Subjects: Irrigation
- Language: English
- Type: Examination paper
- Identifier: vital:17564 , http://hdl.handle.net/10353/d1009900
- Description: Principles of Irrigation: AGC 321, supplementary examination February 2010.
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Advanced Studies in the Field of the Student's Research Project (Horticultural Science): AGH 604
- Authors: Brutsch, M O , Soundy, P
- Date: 2009-11
- Language: English
- Type: Examination paper
- Identifier: vital:17584 , http://hdl.handle.net/10353/d1009931
- Description: Advanced Studies in the Field of the Student's Research Project (Horticultural Science): AGH 604, degree examination November 2009.
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Pedology: AGS 221
- Authors: Muchaonyerwa, P , Wakindiki, I I C
- Date: 2011-01
- Language: English
- Type: Examination paper
- Identifier: vital:17718 , http://hdl.handle.net/10353/d1010126
- Description: Pedology: AGS 221, supplementary examination January 2011.
- Full Text: false
An investigation of skills and knowledge of women participating in water and food security projects in the Eastern Cape Province: a case of Mbekweni village, Sirhosheni and Lutengele villages
- Authors: Makeleni, Maliviwe
- Date: 2015
- Subjects: Agricultural development projects -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11235 , http://hdl.handle.net/10353/d1021306 , Agricultural development projects -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape
- Description: The South African government initiated programmes to ensure that women in agriculture are empowered with sufficient agricultural skills and knowledge to engage in agriculture in order to alleviate poverty for their families and communities. Studies argue that within the agricultural sector, women are not capacitated adequately enough in terms of the skills and knowledge they need to acquire, and particularly as this relates to their ability to have knowledge about more advanced technologies in farming. This includes the most up to date knowledge related to sustainable-development. This study has attempted to investigate skills and knowledge possessed by women participating in water and food security projects in the Eastern Cape. Selected study areas were Mbekweni village located in Whittlesea, Sirhosheni village which is situated in Willowvale and Lutengele village in Port St Johns. The thesis was also aiming to find the skills/knowledge gap amongst the sample so as to come up with recommendations. The data was collected using two semi-structured questionnaires. The first questionnaire was for the main survey which mainly concentrated on the socio-economic information of the respondents. This data were collected from 163 households across three sites using systematic sampling. The second questionnaire was mainly used to gain more in-depth analysis. The data were collected from 30 households across three sites using purposive sampling. Both questionnaires were administered through face-to-face interviews. The majority of respondents have stated that they have basic knowledge and skills in farming, however they need further training on appropriate planting methods for various crops, irrigation scheduling and frequency, application of pesticides and marketing skills. Econometric analysis, through the use of the binomial regression model revealed that education affects the level of knowledge of farmers in selecting appropriate planting methods as well as farmers’ knowledge in determining seed depth of a crop. Gender influences the level of knowledge farmers have when selecting appropriate planting methods. Having extension assistance was recognised to affect farmers’ knowledge in determining irrigation scheduling and intensity. All variables were statistically significant showing a 5% level. The thesis ultimately argues that encouraging support to agricultural extension that respects local-level indigenous farming will increase the food-security potential of residents within the Eastern Cape.
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Assessment of the flocculating efficiency of bioflocculant produced by bacillus sp. Aemreg4 isolated from Tyhume river, Eastern Cape, South Africa
- Authors: Ntsangani, Nozipho
- Date: 2016
- Subjects: Flocculants
- Language: English
- Type: Thesis , Masters , MSc (Biochemistry)
- Identifier: vital:11357 , http://hdl.handle.net/10353/d1021324
- Description: Bioflocculants are flocculating substances produced by microorganisms during growth and have recently received considerable attention from researchers; due to their biodegradability, non-toxicity and lack of secondary pollution from degradation intermediates. This study evaluated the efficiency of bioflocculant produced by Bacillus sp. AEMREG4 isolated from Tyhume River. The bacterial identification was through 16S rDNA sequencing; nucleotide sequences were deposited in GenBank as Bacillus sp. AEMREG4 with an Accession number KP406729. The optimum culture conditions for bioflocculant production were an inoculum size of 4% (v/v) and starch as well as yeast extract as sole carbon and nitrogen sources respectively. The addition of CaCl2 enhanced the flocculating activity, at a wide range of pH 4-10 and the highest flocculating activity was reached at an initial pH 8 (80%). A bioflocculant yield of 0.78 g was recovered from 1 L of culture broth. The optimum flocculating activity of 78% was reached at the lowest bioflocculant dosage of 0.1 mg/ml and the presence of divalent cations (Ca2+, Mn2+ and Mg2+) as well as a trivalent cation (Al3+) enhanced flocculating activity. The purified bioflocculant retained more than 70% flocculating activity when subjected to heating at 100 °C for 1 h and maximum flocculating activity of 83% was achieved at both acidic and basic pH values of 3 and 10 respectively. Chemical analysis showed that the bioflocculant is predominantly polysaccharide. The Fourier transform infrared (FTIR) spectrum revealed the presence of carboxyl, hydroxyl and methoxyl groups as the functional moieties and the scanning electron microscopy (SEM) imaging of the purified bioflocculant showed its morphological structure as rod-shaped which contributes to its high flocculating efficiency. The high flocculation activity displayed by this bioflocculant indicates its potential suitability for industrial application.Keywords: Bioflocculant, Bacillus sp. AEMREG4, flocculating activity.
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Studies on the nutritional value of seven accessions of cocoyam growing in South Africa
- Authors: Lewu, Muinat Nike
- Date: 2010
- Subjects: Taro , Nutrition , Field crops -- Nutrition , Taro -- Nutritional aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11305 , http://hdl.handle.net/10353/d1001054 , Taro , Nutrition , Field crops -- Nutrition , Taro -- Nutritional aspects
- Description: Cocoyam [Colocasia esculenta (L.) Schott] is widely cultivated as a staple food in the tropical and subtropical regions of the world. The crop, however, remains unpopular and not well known outside KwaZulu-Natal Province of South Africa where it is cultivated mainly for subsistence. The aims of the study were to collect local landraces (accessions) of the crop from where it is found growing within the country for various studies and also to document its nutritional values as well as the safety/toxicity of the crop. The study was carried out using various methods. These included a comparative assessment of the proximate, mineral and antinutrient compositions of cooked and uncooked tubers of a typical commercially available cocoyam and potato found in South African markets. These investigations were repeated for the tubers and leaves of available landraces (seven accessions) of C. esculenta found growing in the farmers’ fields in KwaZulu-Natal Province. Also, an in vivo toxicological study on cooked accessions of the local landraces was conducted to determine possible toxicity effects after consumption using albino rats as a model. The results revealed that commercially available cocoyam and potato tubers have very close nutritional components. Analysis of the proximate composition of seven accessions (UFCe1- UFCe7) of cooked and uncooked tubers of cocoyam indicated that UFCe7 was better in ash, crude protein, crude fibre and crude lipid contents but with higher moisture which could make it more vulnerable to microbial attack. No tubers of the seven accessions appeared to be ii outstandingly better than the others based on their mineral compositions. However, in terms of antinutritional factors, UFCe1, UFCe3 and UFCe7 had the least amounts of oxalate, tannins and phytate in their cooked states. It was discovered however, that the leaves of the accessions of this vegetable contain substantial amount of minerals, and therefore, can contribute significantly to the nutrient requirements of humans and could be recommended as a cheap source of nutrients in South Africa. None of the accessions was outstandingly better than the others in terms of their mineral contents and anti-nutritional factors. Moreover, the current study has shown that boiling the leaves of cocoyam prior to consumption is an effective way of reducing the antinutrient contents of the leaves of the plant thereby making it safe for consumption. The findings also revealed that cooking C. esculenta leaves may increase the levels of protein, fibre and lipid contents while cooking may also decrease the mineral, carbohydrate and caloric contents of the leaves of the accessions. The leafy vegetable may, therefore, be recommended as a cheap source of plant protein. Cooking improved the nutritive value as a result of the reduction in antinutrient levels, thereby improving the food quality in all the tuber and leaf samples used for this study. At the same time, cooked samples also suffered loss of some nutrients with respect to the proximate and mineral compositions. However, supplementation from other food sources that are rich in these nutrients is necessary when these crops are cooked for consumption. Any of the cocoyam accessions may be recommended for consumption for improved protein and mineral nutrients while tubers of accession UFCe7 have also shown good promise in terms of protein and fibre content availability. The results of the in vivo study, using the liver and kidney functional endpoints of weanling albino rats (Rattus norvegicus) maintained on different accessions of cooked cocoyam-based iii diets (UFCe1-UFCe7) for 28 days, revealed that all the accessions produced selective alterations on the hepatorenal indices of weanling rats. The highest alterations were produced by UFCe4 while the least was from UFCe2. These alterations may have consequential effects on the normal functioning of the liver and kidney of the animals. The UFCe2 exhibited the least toxicity risk among the accessions of C. esculenta growing in KwaZulu-Natal Province of South Africa.
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Beef Production and Game Farming: AGA 425
- Authors: Chimonyo, M , Mlambo, V
- Date: 2010-01
- Language: English
- Type: Examination paper
- Identifier: vital:17528 , http://hdl.handle.net/10353/d1009817
- Description: Beef Production and Game Farming: AGA 425, degree examinations supplementary examinations January 2010.
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Preparation and characterisation of nanocomposites of biomass and montmorillonite clay for use as biofuels
- Authors: Nyamutswa, Lavern Tendayi
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11345 , http://hdl.handle.net/10353/d1019779
- Description: The aim of the study was to prepare composites of clay and biomass which burn longer than unmodified biomass. Montmorillonite clay was converted to mono-ionic clay by ion exchange with sodium using sodium chloride solution. The mono-ionic clay was organically modified with an organic surfactant, methyl triphenyl phosphonium bromide. Nanocomposites were then prepared by combining the modified forms of the clay with sawdust. The three forms of clay used for the formation of composites were unmodified montmorillonite, mono-ionic montmorillonite and organically modified montmorillonite. The solution blending method was used to make the nanocomposites. FT-IR and XRD analysis showed that organic surfactant increases the interlayer space of the clay since it is bulkier than the inorganic cations that are naturally present in the interlayer space of montmorillonite. The combination of clay and sawdust resulted in the formation of exfoliated nanocomposites as shown by the absence of peaks in the low 2 theta angle in the x-ray diffraction data of the nanocomposite. The nanocomposite which was made from sawdust and 1% organically modified clay showed the best results in terms of burning time and thermal stability, as well as giving a calorific value closest to unmodified sawdust and the least amount of residue.
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Zoology: ZOO 511
- Authors: Masters, P , Genin, F , Parker, D
- Date: 2011-06
- Language: English
- Type: Examination paper
- Identifier: vital:17788 , http://hdl.handle.net/10353/d1010328
- Description: Zoology: ZOO 511, Semester examination June 2011.
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Investigation of local institutions for the application of the in-field rain water harvesting technology in rural areas: the case of Guquka and Khayaletu in Nkonkobe Municipality in central Eastern Cape
- Authors: Mfaca, Malibongwe
- Date: 2011
- Subjects: Rain and rainfall -- South Africa -- Eastern Cape , Water -- Storage , Water-supply , Water harvesting -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11184 , http://hdl.handle.net/10353/d1001031 , Rain and rainfall -- South Africa -- Eastern Cape , Water -- Storage , Water-supply , Water harvesting -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape
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Meat Science: AGA 421
- Authors: Muchenje V , Chimonyo, M
- Date: 2009-11
- Subjects: Meat
- Language: English
- Type: Examination paper
- Identifier: vital:17550 , http://hdl.handle.net/10353/d1009878
- Description: Meat Science: AGA 412, Degree examinations November 2009.
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Tillage and crop rotation impacts on soil, quality parameters and maize yield in Zanyokwe Irrigation Scheme, South Africa
- Authors: Njaimwe, Arnold Ngare
- Date: 2010
- Subjects: No-tillage , Soil mechanics , Soils -- Quality , Cover crops , Corn -- Irrigation
- Language: English
- Type: Thesis , Doctoral , PhD (Soil Science)
- Identifier: vital:11962 , http://hdl.handle.net/10353/460 , No-tillage , Soil mechanics , Soils -- Quality , Cover crops , Corn -- Irrigation
- Description: Intensive tillage and monoculture cropping practices reduce soil C accumulation hence increasing soil vulnerability to chemical, physical and biological degradation. This study focussed on enhancing biomass production of wheat and oat winter cover crops as a means of increasing C sequestration in the low organic C soils of the central part of Eastern Cape Province. The specific objectives were (i) to evaluate the short-term effects of no till and cereal-fallow based crop rotations on; soil organic matter related parameters, pH and electrical conductivity, (ii) soil bulk density, water retention and aggregate stability, (iii) soil microbial biomass C and N, mineralizable N, soil respiration, and dehydrogenase enzyme activity, (iv) grain yield, soil nutrient concentration (N, P and K) and their uptake by maize, and (v) to identify soil parameters with high sensitivity to tillage under maize-fallow-maize, maize-wheat-maize and maize-oat-maize rotational cover cropping practices. The experiment was laid out as a split-plot arrangement in a randomized complete block design with 4 replicates. Tillage treatments (CT and NT) were applied on the main plots which measured 8 × 18 m while crop rotation treatments were applied in the subplots which measured 8 × 6 m. The rotation treatments were maize-fallow-maize (MFM), maize-wheat-maize (MWM) and maize-oat-maize (MOM). Weed control in NT plots involved preplant application of glyphosate to control mainly the grass weeds while post emergence weed management was done using Atrazine (485 atrazine and 15 g l-1 triazines). Initial weed control in CT plots was achieved through ploughing to a depth of 20 cm followed by disking while post emergence weed iii management was done by hand hoeing. Soil parameters measured were; (i) particulate organic matter (POM), soil organic carbon (SOC), total nitrogen (TN), pH and electrical conductivity (EC), (ii) soil bulk density (b), moisture at field capacity (FC), aggregate mean weight diameter (MWD) determined by fast wetting (FW), slow wetting (SW), mechanical breakdown by shaking (MB) and the stability index (SI), (iii) soil microbial biomass C (MBC) and N (MBN), mineralizable N (MN), soil respiration (SR), and dehydrogenase enzyme activity (DHEA). No-till increased POM and TN compared to CT in Lenye and Burnshill, respectively. The MWM and the MOM rotations increased TN relative to the MFM rotation in Lenye. The MWM and MOM rotations enhanced SOC relative to MFM in all sampled soil depths at Burnshill and similar observations were made under MOM rotation in the 5-20 cm depth in Lenye. The MWM and MOM rotations tended to depress soil pH relative to the MFM rotation in both sampled soil depths in Lenye while NT reduced soil pH relative to CT on the surface soil layer in Burnshill. Soil EC and pH varied with depth across tillage practices but both parameters remained within the ideal range for successful crop production over the study period. Soil stability index (SI) and aggregate MWD determined by FW, SW and MB were higher in Lenye compared to Burnshill. The MOM rotation enhanced the SI relative to MFM and MWM rotations at both sites. Scanning electron microscope (SEM) showed that more organic C was incorporated into the soil under NT and MOM rotation compared to CT and MFM rotation which had few organic coatings on the soil particles. Microbial properties varied with plant biomass input as influenced by tillage and type of rotational cover crop at both sites. Like in other past studies, NT showed higher levels of MBC, MBN, NM and SR at the soil surface layer compared to CT in Burnshill. No till increased MN iv relative to CT in both sampled soil depths in Lenye and resulted in higher DHEA compared to CT in Burnshill. The MOM rotation increased MBC, MBN, MN relative to MFM rotation especially within surface soil layer. Similar observations were made with respect to MN and SR in both sampled soil layers at Lenye. By contrast, the DHEA was higher under the MFM relative to the MWM and MOM rotations in Lenye but similar under the MFM and MOM rotations in Burnshill. Maize grain yield was not affected by both tillage and crop rotations but varied with cropping season. Comparable grain yields observed under the two tillage practices with similar fertilizer application rates indicated the advantage of NT over CT in saving on labour costs in maize production without compromising yields. High plant biomass retention under NT relative to CT contributed to high soil N and P levels under the former compared to the latter tillage practice especially on soil surface layer at both study sites. Principal component analysis (PCA) revealed that soil chemical and biological parameters closely linked to organic matter, namely SOC, MN, MBC and MBN showed the highest sensitivity to tillage and crop rotation treatments. Soil aggregate MWD determined by SW and b were the physical parameters which were highly altered by agronomic management practice. The MWM and MOM rotations were clustered together and clearly separated from the MFM rotation and this observed trend only applied to the 0-5 and 5-20 cm depths in Lenye site only. No till, MWM and MOM rotations enhanced POM, SOC and TN relative to CT and MFM rotation suggesting these practices have greater potential to improve soil chemical properties compared to intensive tillage and maize monoculture based production practices. Reduced soil b under MOM rotation and improved SI under NT compared to MFM and CT, respectively v indicate that these practices have the potential to improve degraded soils. Although not significantly different, NT values for MBC, MBN, MN, SR and DHEA were higher compared to CT indicating the potential of the practice to improve soil biotic activity relative to conventional tillage practices. No till enhanced surface soil nitrate N and extractable P compared to CT at both sites revealing the long-term potential of NT in improving the supply of these essential plant nutrients compared to CT. Principal component analysis showed that SOC, MN, K, P, MBC, MBN, soil aggregate MWD determined by SW and b were the most sensitive parameters to tillage and crop rotations. Therefore, these parameters could constitute the minimum data set for assessments of the impact of selected CA practices on soil quality attributes.
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Basic Chemistry: PAC 111F
- Authors: Soyaya, S M , Sadimenko, A
- Date: 2010-06
- Language: English
- Type: Examination paper
- Identifier: vital:17827 , http://hdl.handle.net/10353/d1010381
- Description: Basic Chemistry: PAC 111F, degree examinatino June 2010.
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Ni(II) and Pb(II) dithiocarbamate complexes as precursors for the synthesis of HDA-capped NiS and PbS nanoparticles
- Authors: Chintso, Thobani
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11349 , http://hdl.handle.net/10353/d1020201
- Description: Ni(II) and Pb(II) dithiocarbamate complexes were synthesized and characterized by elemental analysis, UV-Vis, FTIR and TGA and some of the Ni(II) complexes and one Pb(II) were further analyzed by 1H-NMR and 13C-NMR spectroscopy. Generally all the dithiocarbamate ligands are soluble in water while the complexes were soluble mostly in solvents such as chloroform, toluene, DMSO and DCM. Based on the elemental analysis, the dithiocarbamate complexes are formulated as four coordinate (tetrahedral or square planar) compounds. However, the FTIR showed that each of the dithiocarbamate ligands acted as bidentate ligand through two sulfur atoms. The TGA of the most complexes showed one major decomposition step to give respective metal sulfide above 200 oC. In this research project, dithiocarbamate complexes were used as single source precursor for the synthesis of metal sulfide nanoparticles. We studied the optical and structural properties of metal sulfide nanoparticles using UV-Vis, photoluminescence (PL), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorption spectra of the metal sulfide nanoparticles are blue shifted in respect to bulk material and they also showed broad emission. The XRD of the NiS nanoparticles were indexed to the cubic and rhombohedral phase, with crystallite sizes of 15 - 18 nm. The XRD of PbS nanoparticles were indexed to the face centered cubic and cubic rock salts, with the crystallite sizes 12 - 18 nm. The TEM images of the metal sulfide nanoparticles showed particles with spherical and rectangular shapes with crystallite sizes 4 - 35 nm.
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