Synthesis, characterisation and evaluation of functionalized Lignocelluloses-clay nanocomposites for organic pollutant removal from water
- Authors: Mafukidze, Donovan M
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11356 , http://hdl.handle.net/10353/d1021296
- Description: PMPSgLig-NaMMT nanocomposites were prepared from methacryloxypropyltrimethoxysilane (MPS), lignocellulose and montmorillonite clay. The potential enhancement of organic pollutant adsorption capabilities of PMPSgLig-NaMMT nanocomposite from water through functionalization was investigated. PMPSgLig-NaMMT was functionalized by esterification and etherification using different methods so as to increase the surface hydrophobicity of the material and hence improve its compatibility with the target pollutants. Specific chemical routes specially tailored for PMPSgLig-NaMMT were established for functionalization mostly based on the common esterification (Fischer esterification) and etherification (Williamson‟s etherification) reactions. In the functionalization methods, factors such as pH environment, nanocomposite composition, nature of functionalization moiety, and use of or absence of solvents and their variations were studied. FT-IR, XRD, SEM and TGA were used to characterize the synthesized and functionalized nanoadsorbents. The techniques showed successful functionalization via esterification and etherification methods albeit to different extents, with clear retention of the material‟s original structure though there were signs of degradation with some methods. Characterization was supported by adsorption studies to validate implications and draw conclusions. The use of 1,10-phenathroline as a model organic pollutant in water in the adsorption studies showed that adsorbents conformed to monolayer adsorption following pseudo-second order kinetics for adsorption of organic pollutants accurately represented. Most importantly the studies revealed the significant impact of the nanocomposite composition on the overall absorbent performance. Adsorption studies also showed that functionalization via esterification methods gave rise to better adsorbents.
- Full Text:
- Date Issued: 2015
Synthesis, characterization & application of visible light responsive nitrogen doped Tio2 and copolymer-grafted asymmetric membranes with ozonolysis for water treatment
- Authors: Mungondori, Henry H
- Date: 2015
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11350 , http://hdl.handle.net/10353/d1020257
- Description: The use of titanium dioxide for the photo-catalytic removal of organic, inorganic, and microbial pollutants from natural water and wastewater has been considered a very promising technique. The aim of this study was to prepare nitrogen doped titanium dioxide, immobilize it on asymmetric polymeric membranes of poly (methacrylic acid) grafted onto poly (vinylidene difluoride) (PVDF) blended with poly (acrylonitrile) (PAN), and evaluate the photo-catalytic, antimicrobial, and antifouling properties of the membranes. Nitrogen doped titanium dioxide (N-TiO2) nano-particles were prepared by a low temperature sol gel synthesis technique. The modification of TiO2 with nitrogen allows photo-sensitization of the photo-catalyst towards visible light utilization. The N-TiO2 nano-particles were characterized by fourier transform infrared spectroscopy (FT-IR), scanning x-ray photoelectron spectroscopy (SXPS), X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy (DRS), Brunauer Emmett Teller (BET) surface area analysis, and transmission electron microscopy (TEM). The characterizations revealed the presence of the expected functional groups and confirmed successful doping and that the product was visible light responsive. Novel poly (methacrylic acid) grafted onto poly (vinylidene difluoride)/ poly (acrylonitrile) (PMAA-g-PVDF/ PAN) asymmetric membranes were prepared by the dry-wet phase inversion technique. The poly (methacrylic acid) (PMAA) side chains where grafted onto an activated PVDF backbone by reversible addition fragmentation chain transfer (RAFT) polymerization. The photo-catalytic membranes were generated by blending N-TiO2 with the polymer solution before casting the membranes. The membranes were characterized by FT-IR, nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM), and thermo-gravimetric analysis (TGA). FT-IR and NMR analyses confirmed successful grafting of MAA chains onto PVDF while SEM confirmed the successful preparation of membranes with asymmetric structure. The efficacy of the photo-catalytic asymmetric membranes was evaluated on the removal of herbicides from synthetic water. Bentazon was easily degraded while atrazine and paraquat were recalcitrant and proved difficult to degrade. The best results were observed with 3 % N-TiO2-PMAA-g-PVDF/ PAN asymmetric membranes on the photo-degradation of bentazon, atrazine and paraquat in water. Significant enhancement in the photo-degradation of the three herbicides was observed when photo-catalytic degradation was coupled with ozonation. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed the presence of a degradation by-product during the photo-catalytic degradation of bentazon. The photo-catalytic membranes were also evaluated on the photo-catalytic reduction of heavy metals Pb2+ and Fe3+ in water, and the best results were obtained using 1 % N-TiO2-PMAA-g-PVDF/ PAN and 1 % N-TiO2-PAN asymmetric membranes. All prepared photo-catalytic membranes where capable of completely inactivating E. coli ATCC 8739 within 120 minutes of exposure and inactivation rate increased with increasing N-TiO2 photo-catalyst loading. However, there was an indication from the results obtained that N-TiO2 supported on PMAA-g-PVDF/ PAN showed a higher inactivation rate of E. coli ATCC 8739 compared to N-TiO2-PAN and N-TiO2-PVDF membranes. The 1 % N-TiO2-PMAA-g-PVDF/ PAN membranes gave the highest pure water flux (421.83 L/m2h). This increase (PVDF = 30.50 L/m2h, PAN = 73.85 L/m2h) in pure water flux is owedb to PMAA grafting as well as addition of N-TiO2. These modifications resulted in an increased membrane surface hydrophilicity, which promoted permeation of pure water through the membrane structure. A high bovine serum albumin (BSA) rejection (76.5 %) was noted and can be attributed to steric hindrance brought about by PMAA side chains which prevented the bulky BSA molecules from attaching to the membrane surface for PMAA-g-PVDF/ PAN membranes. However, the supporting porous sub-layer of an asymmetric membrane seemed to play a very important role in the overall permeability of a membrane. PVDF membranes are highly hydrophobic hence they gave a very low pure water flux.
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- Date Issued: 2015
The classification performance of Bayesian Networks Classifiers: a case study of detecting Denial of Service (DoS) attacks in cloud computing environments
- Authors: Moyo, Lindani
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11405 , http://hdl.handle.net/10353/d1021327
- Description: In this research we propose a Bayesian networks approach as a promissory classification technique for detecting malicious traffic due to Denial of Service (DoS) attacks. Bayesian networks have been applied in numerous fields fraught with uncertainty and they have been proved to be successful. They have excelled tremendously in classification tasks i.e. text analysis, medical diagnoses and environmental modeling and management. The detection of DoS attacks has received tremendous attention in the field of network security. DoS attacks have proved to be detrimental and are the bane of cloud computing environments. Large business enterprises have been/or are still unwilling to outsource their businesses to the cloud due to the intrusive tendencies that the cloud platforms are prone too. To make use of Bayesian networks it is imperative to understand the ―ecosystem‖ of factors that are external to modeling the Bayesian algorithm itself. Understanding these factors have proven to result in comparable improvement in classification performance beyond the augmentation of the existing algorithms. Literature provides discussions pertaining to the factors that impact the classification capability, however it was noticed that the effects of the factors are not universal, they tend to be unique for each domain problem. This study investigates the effects of modeling parameters on the classification performance of Bayesian network classifiers in detecting DoS attacks in cloud platforms. We analyzed how structural complexity, training sample size, the choice of discretization method and lastly the score function both individually and collectively impact the performance of classifying between normal and DoS attacks on the cloud. To study the aforementioned factors, we conducted a series of experiments in detecting live DoS attacks launched against a deployed cloud and thereafter examined the classification performance in terms of accuracy of different classes of Bayesian networks. NSL-KDD dataset was used as our training set. We used ownCloud software to deploy our cloud platform. To launch DoS attacks, we used hping3 hacker friendly utility. A live packet capture was used as our test set. WEKA version 3.7.12 was used for our experiments. Our results show that the progression in model complexity improves the classification performance. This is attributed to the increase in the number of attribute correlations. Also the size of the training sample size proved to improve classification ability. Our findings noted that the choice of discretization algorithm does matter in the quest for optimal classification performance. Furthermore, our results indicate that the choice of scoring function does not affect the classification performance of Bayesian networks. Conclusions drawn from this research are prescriptive particularly for a novice machine learning researcher with valuable recommendations that ensure optimal classification performance of Bayesian networks classifiers.
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- Date Issued: 2015
The effect of grain and soya bean-based diets on chicken production, some egg quality traits, and the potential for allergen carryover to eggs and meat
- Authors: Dokora, Adia-En-Michelle
- Date: 2015
- Subjects: Chickens -- Nutrition Chickens --Feeding and feeds Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2946 , vital:28192
- Description: This study determined the effect of maize-, whole wheat-, soya bean-based-diets on the growth performance, egg quality and dressing percentage of chickens, as well as the potential for soy and gluten allergen carryover to eggs and meat from chickens. Twenty 36-week-old Lorham White (LW) hens were divided into two groups and kept in individual cages until they reached 39-weeks of age, with water and feed supplied ad libitum. Ten LW hens were fed a maize/soya bean-based diet (T1) and the other ten birds were fed a maize/soya bean-based diet with a 15 percent whole wheat inclusion (T2) for a period of four weeks, with weekly individual hen weights and group feed consumption figures being recorded. After a two-week diet adaptation period, six eggs per treatment group were collected every second day from the LW hens’ to measure egg quality traits. Every third day, over a 29-day period, six eggs per treatment were collected and analysed for the presence of soy, gluten and gluten-derived peptides using allergen specific enzyme linked immunosorbent assays (ELISA) kits. For the broiler trial, a total of 160 Ross 308 mixed sex day old chicks were used in a completely randomized design. Two dietary treatments were assigned to eight cages (replicate) per treatment, with ten birds per cage. The Ross 308 broiler feeding programme consisted of three phases, starter (day 1 to day 10), grower (day 11 to day 20) and finisher (day 21 to day 28). At the beginning of the trial all chicks were fed T1 which contained a maize/soya bean-based diet for a period of 10 days and then eight cages with 10 birds per cage were randomly selected and fed the T2 diet, which contained a maize/soya bean-based diet with a 15 percent whole wheat inclusion, until they reached 28 days of age. Weekly live weights, feed intake, average daily gain and the average daily feed intake were recorded and calculated. At the end of the grower (day 21) and finisher phase (day 28), one broiler bird was selected per cage to have eight (8) birds per treatment and 16 birds per phase that were slaughtered and breast meat samples were analysed in duplicate for the presence of soy and gluten allergens using ELISA kits. The dressing percentage of hot carcasses was also determined at the end of the finisher phase on eight birds per treatment. For LW hens, live weight (LW) at 39 weeks of age, the average daily feed intake (ADFI) and weekly feed intakes (FI) were significantly different (P < 0.05) between treatments with birds on T2 recording higher gains. As birds age in weeks increased, significant differences (P < 0.05) in live weight values were recorded. Egg quality traits measured (shell weight, yolk weight, albumen weight, albumen height and Haugh units) were significantly different (P < 0.05) between treatments, with eggs from hens receiving T1 recording higher mean values. As hens got older, the colour of egg yolk improved, producing eggs with higher b* (yellowness) values and lower L* (lightness) and a* (redness) mean values. The Haugh unit, significantly improved (P < 0.05) as the hens got older, signifying better quality of eggs. For the broiler birds, growth traits measured indicated that there were no significant differences (P > 0.05) in live weight (LW), average daily feed intake (ADFI), weekly feed intake (FI), feed conversion ratio (FCR), cumulative feed intake (CFI) and cumulative gain (CG) between treatments. No significant differences (P > 0.05) between dressing percentage of broilers from the two treatments were observed. As birds grew, significant differences (P < 0.05) in LW, FI, AFI, FCR, and CFI, over a four-week period were recorded. Results of the allergen analyses indicated that soy and gluten allergens were not carried over from feed into eggs and meat of chickens fed a maize/soya bean-based diet and a maize/soya bean-based with a 15 percent whole wheat inclusion, respectively. In conclusion, a maize/soya bean-based diet and maize/soya bean-based diet with a 15 percent whole wheat inclusion that contained soy and gluten allergens, are feed sources that promote and stimulate 36-week-old LW hen and Ross 308 chicken growth.
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- Date Issued: 2015
The effects of distance travelled, lairage duration and animal-related factors on pre-slaughter stress indicators, carcass characteristics, nanostructure and technological properties of beef
- Authors: Chulayo, Amanda Yucca
- Date: 2015
- Subjects: Slaughtering and slaughter-houses -- South Africa -- Eastern Cape , Meat -- Quality -- South Africa -- Eastern Cape , Beef -- Quality -- South Africa -- Eastern Cape , Nanostructured materials -- South Africa -- Eastern Cape , Livestock -- Handling -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11835 , http://hdl.handle.net/10353/d1021275 , Slaughtering and slaughter-houses -- South Africa -- Eastern Cape , Meat -- Quality -- South Africa -- Eastern Cape , Beef -- Quality -- South Africa -- Eastern Cape , Nanostructured materials -- South Africa -- Eastern Cape , Livestock -- Handling -- South Africa -- Eastern Cape
- Description: The main objective of the current study was to determine the effect of distance travelled (DT), lairage duration (LDhr) and animal-related factors (animal class, breed, sex) on pre-slaughter stress indicators, carcass characteristics, nanostructure and technological properties of beef. The study was conducted in an Eastern Cape abattoir under the Buffalo City District Municipality. Six genotypes of cattle (Beefmaster, Bonsmara, Brahman, Holstein-Friesian, Non-descript and Nguni) brought for slaughter at the abattoir on different days were used in the study. Slaughter weight (SWT), warm and cold carcass weight (WCW and CCW), fatness and conformation of each animal were measured and recorded. Representative samples of blood plasma and meat quality from the Muscularis thoracis et lumborum (LTL) were collected at slaughter and 24 hours after slaughter, respectively. Heat shock proteins 70kDa (HSPA1A), glucose (GLU), cortisol (CORT), creatine kinase (CK) and lactate dehydrogenase (LDH) were determined from the blood plasma. The representative LTL muscle was used to determine ultimate pH (pHu), lightness (L*), redness (a*), yellowness (b*), meat temperature (Tm), Warner Bratzler Shear Force (WBSF) and histological structure of beef. There were significant effects of distance on pHu, Tm, a*, b*, TL%, CK and LDH. Pearson correlations were observed between distance travelled (DT), creatine kinase (CK), lactate dehydrogenase (LDH), ultimate pH (pHu), colour coordinates (L*, a* and b*) and Warner Bratzler Shear Force (WBSF). Principal component analysis (PCA) revealed that the 1st (pHu), 2nd (Tm) and 3rd (L*) principal components were the critical meat quality attributes. Positive relationships between carcass weights and beef quality characteristics for bovine cattle where the cumulative percentage of the first six principal component`s (PC`s) (SWT, WCW, CCW, DP, pHu and Tm contributed to 93.4 % of the total variance. Significant correlation coefficients between DT (r = 0.15), LDhr (r = 0.29), Ta (r = -0.52), Tm (r = 0.26), L* (r = 0.33), a* (r = 0.32) and WBSF (r = -0.49) were observed. Meat from Brahman (BR), Non-descript (ND) and Nguni (NG) cows had visible skeletal muscle fibres which were thin and long indicating improved tenderness of beef. Exposing animals to longer hours of transportation did not only reduce glucose levels but also increased the expression of HSPA1A and levels of cortisol. The CK and LDH were not related to beef quality. Therefore, CK and LDH can be used as indicators of animal welfare in slaughter cattle but cannot be used to predict the quality of meat. Bulls were the heaviest, although heifers had the highest dressing percentage than cows. Furthermore, the nanostructure of beef indicated that heifers had the best muscle fibres, sarcomere length and visible intercalated discs. The observed nanostructures of Nguni genotype are an indication of tender meat. Beef from heifers of Nguni had visible and tender meat with traces of intramuscular fat while males had shorter sarcomere length and tougher meat.
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- Date Issued: 2015
The implications of smallholder agricultural productivity growth for poverty alleviation in post-apartheid South Africa
- Authors: Dwesini, Nontembiso Eugenia
- Date: 2015
- Subjects: Agriculture -- Economic aspects -- South Africa , Agricultural assistance -- South Africa , Sustainable development -- South Africa , Agricultural productivity -- South Africa
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11232 , http://hdl.handle.net/10353/d1021286 , Agriculture -- Economic aspects -- South Africa , Agricultural assistance -- South Africa , Sustainable development -- South Africa , Agricultural productivity -- South Africa
- Description: The adoption of the Millennium Development Goal 1(MDG 1) of reducing the rate of poverty to half of the 1990-level by 2015 has been a challenge faced by the developing countries including South Africa. The foundations of democracy have to be continuously assessed so that the obstacles faced by South Africa as it strives towards sustainable democracy are addressed. With agricultural sector identified as having the potential to alleviate poverty compared to the mining sector, manufacturing sector and services sector, it faced the challenges that include: (i) accelerating agricultural productivity; (ii) reducing poverty and vulnerability; and (iii) narrowing rural-urban income disparities. The identification of the critical linkages in the agricultural development framework allows for effective strategic planning, effective decision making and appropriate policy formulation. Expectedly, the sector has attracted considerable fiscal policy interest and public investments. The primary aim of this research study is to assess the extent to which smallholder agricultural productivity growth alleviates poverty in South Africa. The statistical and econometric techniques namely; Johansen technique of co-integration analysis (1995), analysis of covariance and correlation, Vector Error Correction Model, are employed in this research study. The data description, data sources, expected relationship between variables and indexation of data are done. The drivers and cause-effect relationships between agriculture and poverty reduction are investigated. The employed models allowed for an exploration of plausible future growth in agricultural elasticity of poverty and the possibility of reducing poverty level in South Africa. The data is obtained from the National Department of Agriculture from 1994 -2013. The analysis of the results strongly confirms that agricultural productivity has a significant inverse relationship to the levels of poverty in South Africa. The outcome of the analysis will contribute to improved decision making on the use of public funds in agriculture.
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- Date Issued: 2015
The investigation of perceptions of professional nurses regarding care of mental health care users in a general hospital setting
- Authors: Manona-Nkanjeni, Nonkanyiso Yvonne
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Nursing Science)
- Identifier: vital:11924 , http://hdl.handle.net/10353/d1020200
- Description: This study sought to explore the perceptions of professional nurses regarding care of stabilised mental health care users in a general hospital setting. A qualitative, explanatory, descriptive and contextual design was used for the study. A non-probability, purposive sampling method was used to select 12 participants from the Cecilia Makiwane Hospital in Mdantsane. Data were collected through semi-structured interviews. The services of an independent interviewer were used to avoid any bias as interviews took place where the researcher is employed. The services of an editor were also used for language control (see Annexure H). The researcher repeatedly listened to the tapes used for data collection until completely satisfied with the interpretation of verbatim data. The research study was conducted in an ethically reflective manner and trustworthiness was ensured at all times. Four themes emerged from the analysis of the interviews: fear, stigma, myths and training. The researcher utilised the services of an independent coder who verified the identified major themes. The findings revealed that participants were fearful due to lack of knowledge, experience and psychiatric nursing skills. Participants feared because they lack knowledge about psychiatric medication and because mental health care users may have relapse. The participants also attached a stigma to mental health care users, which resulted in poor communication between participants and the stabilised mental health care user; a negative attitude towards mental health care users; and non-acceptance. Participants believed in myths about mental illness; they regarded it as contagious; and perceived mental health care users as dangerous. The participants strongly recommended that training should be provided to improve their knowledge and skills to enable them to care for stabilised mental health care users in a general hospital setting. The following should be facilitated: in-service training; adoption of a positive attitude; dispersal of myths and fear; education about referral systems; and allocation of specialist psychiatric nurses to medical wards for referral purposes with regard to complicated cases.
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- Date Issued: 2015
Tillage effects on the aggregate-associated organic carbon and bulk density in some South African soils with different texture
- Authors: Njeru, Sarah Kangai
- Date: 2015
- Subjects: Soil management Tillage
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2512 , vital:27881
- Description: Tillage operations disrupt the soil structure resulting in aggregates of various sizes and altered bulk density. Moreover, tillage influences soil carbon pools and many other soil physical properties. The objectives of this study were to determine, in various South African soils under different tillage systems, the following. (1) Amount of aggregate-associated soil organic carbon (SOC), (2) soil compressibility, and (3) relationship between compressibility, texture and the aggregate-associated SOC. The soil samples used in this study were collected from six different sites in Eastern Cape Province, South Africa. Soil samples were taken from conventional tillage (CT) and no-till (NT) land. To keep the soil aggregates intact sampling was done using a spade and carefully carried to the laboratory in rigid containers. For SOC determination, treatments were the two tillage systems, CT and NT, and four aggregate sizes. The experimental design was completely randomized design with a factorial layout and was replicated three times. Aggregate-associated SOC was determined using Walkley-Black method. Proctor compaction test was used determine the dry bulk density with varying moisture content and consequently the maximum bulk density (MBD) and critical water content (CWC). The aggregate-associated SOC content differed with tillage system and was significant higher (p < 0.05) in CT than NT. The amount of aggregate-associated SOC was 1.67 times higher in CT than NT plots. The MBD ranged between 1.77 g/cm3 and 10.27 g/cm3 and the CWC ranged from 9.1 percent to 10.3 percent. The higher amounts of SOC in CT were attributed to the annual crop residue returns while the lower amounts of SOC in the NT fields were due to grazing. Therefore, tillage influenced the amount of aggregate-associated organic carbon irrespective of the resulting size of the aggregate. The positive relationship between tillage and aggregate-associated SOC challenges the conversion of land to no-till for carbon sequestration. The overall gradient for correlation between the MBD and CWC was negative with r2 = 0.23 and a p value of 0.0076. The compressibility curves indicated higher values under CT if the texture class was silt clay.
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- Date Issued: 2015