Postgraduates: PACE Seminar Series 2007

Friday Forums start at 3:30 pm and are held in the Doug McDonnell Building, Room 711 - unless otherwise stated.

Past presentations and abstracts

26 Jan 2007 - Peter Asimakis - Protein Aggregation during Processing

Protein therapeutics has emerged as one of the fastest growing areas of the pharmaceutical industry. A major issue for protein therapeutics is the susceptibility of proteins to denaturation during manufacture and their instability in liquid formulations. As a result, many protein therapeutic manufacturing processes are low yielding and often the final product is only stable in the frozen or freeze-dried form. Liquid formulation of protein therapeutics is desirable as it reduces manufacturing costs and enhances convenience to the end user. Instability of liquid formulation often presents as formation of aggregates upon storage. If the propensity for protein instability can be reduced during the manufacture and storage of protein therapeutics, yield and shelf-life may be increased.

A model protein, â-lactoglobulin was used to understand the effects caused by processing proteins and the causes of instability during manufacturing. This was achieved by focusing on the heating and shearing of proteins, which are common in processing, typically in the form of mixing, pumping, filtering and pasteurisation. Rheofluorescence methods were used to monitor fibril growth during the heating and shearing of protein solutions. This study has shown that conditions encountered during the manufacture of protein therapeutics may result in fibril formation.

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30 Mar 2007 - Rudi Spehar - Modelling of the role of shear in compressional dewatering

Gravity thickening is a dewatering process that is in high demand in the minerals and waste treatment industries as it can process high volumes of low solid concentration suspension and is relatively inexpensive. The aim of thickening is to increase the solids concentration of particulate slurries by exploiting the difference in densities between the solid and liquid phases. The unit equipment item in which thickening is conducted is referred to as a "thickener". A thickener is essentially a large vessel in which a particulate suspension is allowed to settle out into a particulate rich underflow and particulate free overflow using gravity as a driving force.

Although thickening is "old" technology and the premise behind it is relatively straightforward, existing dewatering theories are yet to successfully predict industrial thickener behaviour. One of the reasons for this lack of success is that current models do not take into account in-situ shear processes. For example most thickeners contain a rake which was primarily designed to draw concentrated suspensions away from the wall and into the underflow region in order to prevent "caking". However, by doing so, the rake also imparts a shear which affects the fundamental material properties and thus the dewaterability of the particulate suspension. The aim of this work is to model thickener behaviour with an emphasis on shear in material dewaterability. This will allow for further optimisation of industrial thickening processes which is vital in reducing expenditure and providing sustainable process operation!

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30 Mar 2007 - JP O'Shea - Temperature sensitive flocculants for improved thickening

Gravity settling and sediment consolidation are suspension dewatering processes fundamental to many industries such as mining and paper milling. This presentation will discuss progress made in the development of a flocculant based upon poly(N-isopropyl acrylamide) (PNIPAM) that is responsive to temperature such that these processes are optimised. Fast settling requires inter-particle attractions so that floccs can form and be influenced by gravity. In contrast, the consolidation step requires inter-particle repulsion so that water entrapped in the floccs can escape. Although fast settling is currently achieved through bridging flocculation caused by the addition of high molecular weight polymers (flocculants), the interparticle attractions induced mean that the secondary consolidation step is a protracted process.

The first part of the presentation will describe the mechanisms through which PNIPAM based flocculants effect adsorption to solid-surfaces and hence flocculation and settling. The second part will demonstrate the advantages that PNIPAM based flocculants have compared to a Polyacrylamide based flocculant typically used in industry, using the key performance indicators of settling rate and supernatant clarity.

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27 Apr 2007 - Sarah Shaw - Synthesis of polymers with pendent aldehyde functionalities

The use of polymers for biological purposes, particularly as drugs or drug carriers, attracts a great deal of interest, as polymers offer a number of advantages over traditional candidates. The focus of this research is the synthesis of polymers that contain pendant aldehyde groups. The principal application of these polymers is anticipated to be as antimicrobial agents. Aldehydes have well-established antimicrobial properties, arising from their high reactivity towards the amino groups of proteins on the surface of microorganisms.

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27 Apr 2007 - Jing Fung Tan - Delaying the onset of macrogelation via 'binary solvent' effects

The main aim of this project is to find cost-effective and environmentally acceptable methods of synthesising functionalised, high molecular weight polymers with low viscosity for use in the automotive coatings industry.

It is well known that core cross-linked star (CCS) polymers exhibit superior rheological properties to their linear counterparts, such as low viscosities at high molecular weights. This makes them ideal for use as binders in paint. However, the high environmental and economic costs associated with producing these well-defined polymers via ‘living’ radical polymerization methods make industrial scale-up difficult. Consequently, polymers exhibiting similar properties to CCS polymers were produced via conventional free radical polymerization methods to reduce the impact of these factors on the synthetic procedure.

This research focuses on increasing the yield of the production process by investigating and understanding solvent effects on the polymerization reaction and utilising these effects for the optimisation process. This would allow a reduction in the amount of solvent used in the process which would in turn, reduce the solvent emissions into the environment and save on solvent costs.

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25 May 2007 - Rory Anderson - Nanoparticle formatio and stabilisation at high solids concentration in aqueous systems

Nanoparticles have a diverse range of novel properties and therefore a host of potential applications that can be exploited economically, for both the consumer and niche markets. These uses may simply be an improvement on already available technology or through exploitation of their unique properties, allow for innovative and new applications. However in order for these applications to be generally accessible, an economically viable method of mass production needs to exist. As a result of this there is significant research into both the novel properties of nanoparticles as well as methods of production. The main aim of this project is to determine a viable method of synthesising highly concentrated nanoparticle dispersions in aqueous systems through the use of novel stabilising polymers and surfactants. This research focuses on the nucleation and growth mechanisms of nanoparticle synthesis as well as optimising the ability of novel polymers to stabilise these particles.

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25 May 2007 - JP O'Shea - Temperature mediated adsorption of Poly(N-isopropylacrylamide) onto α-Alumina

The adsorption of various molecular weight poly(N-isopropyl acrylamide) (PNIPAM) polymers onto α-alumina has been studied at pH 5 with equilibration conditions both above and below the lower critical solution temperature of the polymer (~32oC). It was found that adsorption increased dramatically upon increasing the temperature above the LCST across the molecular weight range investigated. Using Fluorescence spectroscopy, this trend was explained by the increase in hydrophobic interactions which increase with increases in concentration and molecular weight causing the increased formation of inter-molecular aggregates.

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29 Jun 2007 - Rachael Wall - New Approaches to Dairy Sludge Dewatering

Optimisation of the design and operation of wastewater treatment practices is of primary importance to a range of processing industries including the dairy industry, particularly as environmental and financial restrictions continue to limit the sustainability of current biomass disposal options. Research under this project has been driven by a change in the approach to biological sludge processing, which recognises the opportunities available to pretreat a wastewater to improve effluent quality and sludge dewaterability through an understanding of the influence of treatment conditions on sludge composition. This presentation gives details of the results of a ten-week bioreactor study that examined the influence of the feed multivalent-cation balance on sludge composition and dewatering behaviour. The results of this study have presented a number of opportunities to further examine the relationships between the monovalent/divalent cation balance and character of extracellular polymeric substances in the bulk and dispersed sludge phases.

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27 Jul 2007 - Annette Haebich - Selective adsorption of Chiral Molecules at solid-liquid interfaces

Chiral compounds are molecules that cannot be superimposed with their mirror image, which results in two distinct isomers called enantiomers. Biological molecules like amino acids and sugars are chiral and in nature nearly always appear in one form.

In pharmacology only one enantiomer may be medically active, whilst the other may be pathogenic (e. g. Thalidomide). Thus an enantiomerically pure synthesis is desirable but not always possible; so separation of the enantiomers is undertaken by chromatography on a chirally active column. The separation efficiency depends upon column material used in a specific system.

To make separation of chiral compounds more effective it is necessary to understand the interactions between a chiral molecules on amolecular level, which have been only quantitatively studied in the past.

In this project chiral interactions between different amino acid surfactants and a chiral surface shall be studied by the use of attenuated total reflection infrared spectroscopy (ATR-IR) and ellipsometry.

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31 Aug 2007 - Claire White - ¹⁷O MQMAS NMR characterisation of geopolymers

A geopolymer is a man-made material which has great potential in numerous applications including the construction industry and the immobilisation of nuclear and toxic waste. The material is created by mixing an aluminosilicate solid with an alkali-silicate solution, which forms a hardened gel. To date there has been considerable research conducted on geopolymers. However, for geopolymers to become a viable alternative to Portland cement, additional research needs to be conducted on their mechanical and chemical properties. An important chemical aspect of geopolymers that governs strength and durability is the percentage of Al-O-Al linkages. Si-O-Si and Si-O-Al linkages are more stable than Al-O-Al linkages in aluminosilicates, hence a greater percentage of Si-O-Si and Si-O-Al linkages results in a stronger material. Until now, it has been generally accepted that geopolymers obey Loewenstein’s rule, which states that Al-O-Al formation is avoided. However, results from ¹⁷O MQMAS NMR, along with statistical thermodynamic modelling, have indicated that Al-O-Al is present in geopolymers. The purpose of this presentation is to provide an overview of the analysis process, the results obtained, and the underlying chemical principles governing the nanostructure of geopolymers.

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31 Aug 2007 - Ailar Hajimohammadi - Synthesis of One-Part Geopolymer Mixes

Geopolymerisation is a technology capable of turning industrial wastes into strong and chemically durable cementitious binders. The synthesis of geopolymers can start from a variety of aluminosilicate sources such as fly ash or metakaolin. At present, the most commonly used building material is ordinary Portland cement (OPC). However, OPC has a negative environmental effect during synthesis, with the release of significant amount of CO2 greenhouse gas. The cement industry is responsible for 5% of total global anthropogenic CO2 emissions. In geopolymer technology; silicate solutions are frequently used in alkali activation for dissolving the aluminosilicate to produce the binder. Sodium aluminate solutions have also been used. These corrosive and often viscous solutions are not user friendly, and would be difficult to use for bulk production. Developing geopolymers as a 1-part mixture just add water similar to OPC increases their commercial viability.  In the present work geothermal silica and sodium aluminate are used as solid silica, alkali and alumina sources for the production of geopolymer cement. X-ray diffraction is used to identify and characterize crystalline phases forming; however the main reaction product is X-ray amorphous. Results of attenuated total reflectance Fourier transform infrared spectroscopy indicate that the structure of the 1-part mix geopolymer cement is similar to that of geopolymer cement made from the alkali activation of fly ash. Microstructural analysis is also performed for this system. Results indicate that by using solid silica and sodium aluminate it is possible to produce geopolymers in a 1-part mixture.

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28 Sep 2007 - Hang Ta - Site specific drug delivery system for cancer treatment

Directed drug delivery has a number of significant advantages over general administration. Controlled delivery allows reduced levels of drug to be administered for similar efficacy. In summary, controlled delivery has both improved patient outcomes and significant economic benefits in reduced drug requirements. Several different methods have been researched to control directed delivery. Our project is developing a novel biopolymer cross linking system which is liquid at room temperature and gelled at body temperature when injected subdermally or to tumour sites where the cytotoxic drug or therapeutic plasmid is required. A range of gel properties are available to regulate the delivery of both drugs and plasmids. The project investigates the release rates of Doxorubicin (Dox), a cytotoxic drug, and Pigment Epithelium-Derived Factor plasmid (pPEDF) in vitro over a range of gel conditions. This knowledge will be used to optimise the release rates of Dox and pPEDF for targeted tumour and subdermal delivery.

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28 Sep 2007 - Hemadri Saha - Optimisation of Plate and Frame Pressure Filtration

Optimisation of solids extraction from a suspension has been an important issue for the minerals industry for a long time. Various filtration techniques are available to separate solids from solid-liquid mixture. However, it has been a challenge for the minerals industry to achieve both maximum throughput and low moisture content in a moderate to highly incompressible materials in a cost effective way. This study has investigated ways in which existing filtration theory and dewaterability characterisation techniques could be developed, refined, validated and applied to filtration optimisation problems in the minerals industry, especially for incompressible materials. Using a number of full scale filter load cell data analyses, it has been demonstrated that the most effective routes to higher filter solids throughput are through the identification of redundant filter cycle time and using a higher feed solids concentration.

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26 Oct 2007 - Michael Simioni - Making "Clean Coal" with Pervaporation

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