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(2011)Journal ArticleThick anatase films were fabricated on graphite substrates using a method of anodic aqueous electrophoretic-deposition using oxalic acid as a dispersant. Thick films were subsequently fired in air and in nitrogen at a range of temperatures. The morphology and phase composition were assessed and the photocatalytic performance was examined by the inactivation of Escherichia coli in water. It was found that the transformation of anatase to rutile is enhanced by the presence of a graphite substrate through reduction effects. The use of a nitrogen atmosphere allows higher firing temperatures, results in less cracking of the films and yields superior bactericidal performance in comparison with firing in air. The beneficial effects of a nitrogen firing atmosphere on the photocatalytic performance of the material are likely to be a result of the diffusion of nitrogen and carbon into the TiO2 lattice and the consequent creation of new valence band states.
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(2010)ThesisThis thesis evaluates the MicroFoss system, also known as the BioSys or the SolerisÒ system, as a rapid method for microbiological analyses of eggs and egg products. Commercially assays for assessment of microbiological quality and sanitation conditions during processing, which are total viable counts (TVC), coliforms and Escherichia coli, are evaluated in comparison to the cultural methods. Concurrently, this thesis reports development of a new medium for the MicroFoss Salmonella detection, since this test is not available. Good correlations between the cultural TVCs and the MicroFoss detection times (DTs) were obtained (r ³-0.84) in all egg products. Preliminary results of a correlation between the cultural TVCs dominated by Pseudomonas fluorescens and the MicroFoss DTs suggested that the MicroFoss could be used for investigation of spoilage and shelf life prediction of eggs. High agreements (r ³-0.93) between the MicroFoss and cultural methods for coliforms and E. coli in eggs and egg products was achieved as well as the accuracy, sensitivity and specificity. The MicroFoss for estimations of TVC, coliforms and E. coli could be completed in less than 24h, compared to 48-72h required for the cultural methods. Hence, the MicroFoss could be used as a rapid screening for quality control of eggs and egg products. While a new propylene glycol-based selective medium developed was effective for detection of Salmonella, possible false positive results caused by certain bacteria, such as Enterobacter cloacae, E. coli, Klebsiella pneumoniae and Proteus mirabilis, were encountered. When this selective medium was supplemented with 40 mg/L of novobiocin, or 1 or 2 mL/L of Niaproof 4, these non-salmonellae were greatly suppressed or eliminated, particularly Pr. mirabilis, whilst this did not affect growth of Salmonella. Various serotypes of Salmonella including strains of atypical biotype were able to acidify propylene glycol in these media. Detection of Salmonella in naturally contaminated eggs by the MicroFoss using propylene glycol-based selective media showed equivalent sensitivity and specificity to the Australian Standard 5013.10-2004, according to numbers of egg samples tested in this study. Detection of low level of Salmonella (1-10 CFU/25g of eggs pre-enriched in buffered peptone water) was achieved in less than 24h.
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(2011)ThesisBiodiesel is touted as potential alternative energy to reduce the over-dependency upon the depleting and hazardous hydrocarbon fuel. The pursuit of a feasible biodiesel technology however still remains due to the feedstock limitations of the conventional inorganic-catalysed methods. The design of a process that is adaptable to the nature of low-grade and non-edible oils or fats such as those using lipase-catalysed process is thus favourable. Therefore, the main thrust of this thesis is to employ a novel extractive basket impeller column (BIC) reactor for the production of biodiesel. Studies on the inherent reaction kinetics of the production of ethyl oleate (key fatty acid ethyl ester (FAEE) from the biodiesel process using bioethanol) by ethanolic esterification and transesterification reactions of oleic acid and waste cooking oil (WCO) respectively, were conducted under monophasic and biphasic (two-immiscible liquid) conditions using Novozym 435 lipase as biological catalyst. Feed reactant-mole ratios and initial water contents were varied. In microaqueous environments, the Ping-Pong-Bi-Bi kinetic model of the esterification reaction revealed an optimum at a stoichiometric mixture of ethanol-oleic acid and was similarly demonstrated in the reaction rate analysis of waste cooking oil transesterification. In biphasic media, the maximum rate was further increased and a sinusoidal trend that was probably attributed to the dynamic ethanol distribution and the conformational change of lipase active site due to water interaction. Interestingly, in the biphasic esterification reaction with simultaneously-varied feed ratios, the optimum was skewed at a 4-fold molar excess of oleic acid. As the reaction rates were enhanced from the use of water probably associated with the positive allosterism of the lipase, the potential of a solvent extraction system using water was consequently investigated using the BIC. Preliminary tests using a single stage operation revealed that besides having an optimum stirring speed, the reaction yield also improved when the viscosity of the substrate was reduced at the same stirring speed, even though viscosity reduction involved the use of ethanol, a competitive inhibitor. This phenomenon is probably due to flow restrictions imposed by the basket mesh on relatively high viscous oily co-reactant. At a stirring speed of 600 rpm and above, a vortex probably formed creating a saturated low-viscous-liquid zone attributed to the swirling ethanol phase as evidenced by a dilatant characteristic of shearing stress during agitation and the subsequent GC analysis. These rheological issues and the probability of vortex formation are influential factors in the extractive reaction using the basket impeller. Reaction rate studies were conducted at different solvent-feed ratios and stirring speeds in a 9-stage BIC column. The Damköhler number obtained was below unity suggesting that the reaction occurred at an excellent extraction condition. Significantly, the efficiency of the column was more than 200% compared to a single stage operation. This study also showed the negative effect of high WCO flow relative to the ethanol aqueous flow and the deterioration effect of stirring at speeds higher than 500 rpm due to the aforementioned vortex appearance. Using the reaction rate data collected at the optimum BIC condition, a fixed capital cost analysis was performed and consequently revealed feasibility of this extractive reaction concept can achieve a 50% reduction in the production cost of 8000 tonnes per annum production.
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(2013)ThesisIn this thesis, NOM removal by coagulation, advanced oxidation and adsorption process (with advanced oxidation for regeneration) were studied with the ultimate aim to improve water treatment technologies and treatment trains. The work starts with the development of novel PACl-chitosan composite coagulant for removal of NOM from water. It was confirmed that there is an intermolecular interaction between Al species and chitosan molecules as shown by the presence of Al-NH2 bonds in the composite coagulant. Improvement in the removal of NOM from synthetic water was observed at lower Al dosage when PACl-chitosan composite coagulant is used compared to PACl coagulant. However, a slight improvement in the removal of UV254 absorbing components of NOM was observed when natural water was treated with PACl-chitosan. Using UV-visible spectroscopy analysis, it is observed that PACl-chitosan is more effective than PACl for treating water containing higher levels of activated polyhydroxyaromatic moieties. The second part of the thesis focused on the study of the organic matter transformation as a result of oxidation process using titanium dioxide (TiO2). The degradation rate in the UVA/TiO2 process varied depending on the pH of the reaction, with faster removal rate at lower pHs. It was found that humic substances and building blocks are two of the components that contributed to the formation of THM. Short period of UV irradiation leads to high trihalomethanes formation potential (THMFP) levels for waters at neutral and basic pHs, while lower THMFP values were observed for water at acidic condition. The last part of the thesis focuses on the design of a magnetic photocatalyst (Fe3O4@SiO2@TiO2) to rapidly remove NOM from water by adsorption and thereafter can be effectively regenerated by light irradiation in a post treatment process. NOM adsorption on magnetic TiO2 was found to rapidly reach equilibration, with a majority of the organic matters adsorbed within 5 min. The THMFP after treatment was either within the range or lower than the acceptable Australian limit (250 μg.L-1) and these levels were sustained throughout the five adsorption-regeneration cycles. Significant enhancements in the organic removal as well as THMFP values were observed for adsorption at lower pH.
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(2013)ThesisThis thesis used RAFT polymerisation to generate glycopolymers capable of binding therapeutic agents through hydrogen bonding or direct complexation to the sugar units. Firstly, block copolymers comprising of a nucleoside and a glucosamine-based block were synthesized in a controlled fashion, and structures formed by self-assembly of the resulting block copolymers found to vary according to the polynucleoside block length. The ability of the polynucleoside block to interact with adenosine was promising for the use of these particles in encapsulating small molecules through hydrogen bonding. Secondly, glycopolymers were synthesized in which the glycopolymer played a new role compared to traditional glycopolymer applications. New thiosugar monomers were developed which were polymerized by RAFT in a controlled manner to generate glycopolymers capable of complexing Au(I). The polymeric analogues of potent gold(I) chemotherapeutics showed promising anti-cancer activity against ovarian cancer cells.
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(2013)ThesisThe object of this thesis is to synthesis new for the delivery of platinum chemotherapeutics. Water soluble block copolymers were initially synthesised using oligo(ethylene glycol) methylether methacrylate (OEGMEMA) and methacrylic acid (MAA) and upon the attachment of platinum (IV) complex (Oxoplatin) the polymer becomes amphiphilic and self assembles into micelle structure in aqueous environment. The surfaces of these macromolecular micelles are decorated with folic acid for enhanced tumour targeting ability and are internalised via specific cellular uptake pathway – receptor mediated endocytosis (RME). The attachment of folate is achieved via the R-group modification of the RAFT agent used in polymerisation resulting in polymers to terminate with a dopamine functionalised end group. The attachment between folate and the terminals of the polymer exist in a reversible boronate ester group and its binding conditions have been investigated in this thesis. The in vitro studies show a promising antitumor activity from the platinum (IV) incorporated micellar delivery system and that the cytotoxicity can be enhanced by stabilising the micelle structure via crosslinking and the attachment of folate on the surface for pathway specific endocytosis. The cytotoxic properties of platinum incorporated micelles can also be increased by utilising a dual drug system with curcumin which has also been explored in this thesis.
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(2013)ThesisThe aim of the present study was to develop a specific and quantitative analytical method to determine the individual concentrations of naturally occurring phenolic acids and flavonoids and their metabolites in food; then evaluate the antioxidant capacity of the quantified phenolic acids using different assays. An LC-MS/MS method for the quantification of 9 phenolic acids and 5 commonly present flavonoid compounds in plant foods was developed. Target analytes were the benzoic acid based phenolic acids - anisic, gallic, salicylic, protocatechuic, and vanillic acid, together with the cinnamic acid based phenolic acids - caffeic, p-coumaric, ferulic and sinapinic acid. As for the flavonoids, target analytes were apigenin, luteolin, kaempferol, quercetin and myricetin. These compounds were identified by retention times and comparison of electron impact mass spectra. Deuterium-labelled ferulic acid and 13C-labeled quercetin were used as the internal standards to achieve accurate quantification. Purification was accomplished using Strata® SDBL (styrene-divinylbenzene) cartridges for solid phase extraction (Phenomenex, US). Sample extracts were subjected to acid and/or alkaline hydrolysis to release the free phenolic acids and flavonoids from the ester and glycoside forms found in plant materials. The resolution and quantitation of all compounds were excellent with linear calibration curves over the range detection limit for each compound to 750 ng/µL and correlation coefficients (R2) greater than 0.9643. The intraday assay range of relative standard deviation (RSD) was 2.6-9.0 for high concentrations and 2.3-16.7 for low concentrations of a standard mixture. For interday assay, the relative standard deviation (RSD) ranges were 10.8-20.2 for high concentrations and 12.7-19.4 for low concentrations. Percentage recovery of analytes were satisfactory (72 to 128% respectively) and within the acceptable limits of bioanalytical method validation guidelines (FDA, 2001). The developed and validated method was applied to different types of Malaysian traditional vegetables, fresh (n=15). The results revealed that flavonoids are the most abundant polyphenols in plant extracts, followed by hydroxycinnamic acids of phenolic acids, mostly in bound form as esters or glycosides. Only hydrophilic antioxidant activities of all selected samples were examined using ORAC assay. In addition the antioxidant capacity of the identified free and bound phenolic acids content was measured using different assays including ORAC, ABTS, and DPPH assay (end-point assay and kinetic assay). The results indicate that the total phenolic acids content did not correlate positively with antioxidant activity, but the total flavonoid content was positively correlated with antioxidant activity. In conclusion the analytical method presented is robust, safe, and generally applicable to the analysis of free and bound phenolic acids and flavonoids in food samples.
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(2013)ThesisA solar heat recovery dryer for drying coffee beans was designed and tested based on heat recovery through condensation. A mathematical model of the dryer was built based on heat and mass transfer, fluid flow and boundary analysis. Experimental data from the first run was used to estimate two critical constants in the model, and seven subsequent runs at different conditions were used to validate the model. The simulated results and the experimental data correlated well (r = 0.97). Design of the solar heat recovery dryer was then optimized in terms of annual profit, estimated from operation, maintenance, construction and product costs. The three parameters optimized were the dryer height, length, and the depth of the coffee bed. A sensitivity analysis of the profit equation showed that the tray area, density of coffee beans and the price of labour had the most effect on profit. From this, a suitable design of the solar heat recovery dryer was developed for local conditions.
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(2010)Conference PaperAn opportunity to explore the topic of data usages is presented by the collaborative research being undertaken by a federation of applied science research units affiliated with a number of different Australian research organizations (the Cluster). The research aims to investigate how members of the collaboration understand and work with data in their day-to-day practice.
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(2012)ThesisA range of γ-alumina supported (Norton type SA 6176 and Puralox SBA 200) cobalt-based Fischer Tropsch catalysts were synthesized via an impregnation method. Initially, catalyst preparation involved (aqueous) impregnation conducted at pH 2 using 3 M nitric acid with cobalt promoted with either lanthanum and/or ruthenium on Norton γ-alumina support. The presence of promoters (La, Ru) improved the methanation activity with the combination of La and Ru giving the best performance. The presence of promoters altered the physicochemical properties, Co crystallite size and the extent of Co3O4 reduction (to metallic Co) of the catalyst. Impregnation using a non-aqueous technique (ethanol and acetone mix, ratio 1:4) was performed on Puralox γ-alumina support with the catalysts experiencing a similar effect as for aqueous impregnation. Non-aqueous synthesis was found to influence methanation activity due to the modification of surface properties leading to variations in cobalt crystallite size and improved cobalt metal dispersion. The enhancement derived primarily from differences in the pore structure and its influence on Co crystallite size. The Puralox γ-alumina gave a better catalytic performance compared to Norton with CoRu/La/Puralox being the best catalyst and promoter combination. Catalyst reduction conditions (H2 partial pressure, holding time, final reduction temperature and ramp rate) were varied and the impact on performance for the atmospheric Fischer Tropsch reaction on CoRu/La/Puralox was assessed. Changes to these parameters altered the extent of cobalt reduction, the interaction between cobalt-cobalt atoms and cobalt-support and the Co° crystallite size. The optimum catalyst activity was obtained at 100 % H2, 450 °C reduction temperature, 50 hr holding time and 0.5 °C/min ramp rate and represented a balance between the extent of cobalt reduction and cobalt sintering. Ultilisation of a reduction-oxidation-reduction (ROR) strategy to activate the catalyst for the atmospheric Fischer Tropsch reaction was also investigated. Re-oxidising and then re-reducing a previously reduced catalyst was observed to improve its activity. A re-oxidation temperature of 135 °C gave the highest activity improvement. A decrease in the temperature of the second reduction step (from 450 °C to 300 °C) was also found to improve catalyst performance, likely due to a decrease in Co° sintering.