Master of Science

thesisCutting fluids, typically an emulsion containing a lubricant within a larger cooling medium, are expected to reduce the cutting temperature at the interface between the chip and tool in machining, which improves both part quality and tool life. Traditionally, cutting fluids are applied as a flood, completely wetting the tool for maximum heat removal. However, flood coolant has adverse effects on both the environment and workplace safety, leading industry towards developing alternative solutions, such as dry and minimum quantity cutting fluid (MQCF) application. The capability of MQCF to access and cool the tool-chip interface is not completely understood or modeled with no ability to deliver a desired fluid volume to achieve a desired temperature or friction reduction. This research attempted to model and study dry, flood, and various levels of MQCF cooling targeted onto the rake face of the tool. Experiments were conducted to determine the effectiveness of each level of fluid condition, which could then be parameterized as an effective heat transfer coefficient, heff. The model created here is based off of an established dry analytical model and now expands its capabilities to model machining operations under varying levels of coolant application. The model presented in this thesis was validated with Oxley's model, which is widely accepted as the most comprehensive and accurate machining model for plain carbon steels. All machining parameters input into Oxley's model were held constant, but feed rate was increased from 0.05 mm/rev to 0.2 mm/rev. The model closely predicted the increase in average tool-chip interface temperature, but did not agree with the predicted average tool-chip interface temperatures. To determine heff, a near-orthogonal facing experiment on 1045 steel was conducted to measure the change in temperature under six cutting fluid conditions, including dry, MQCF (0, 150, 300, and 500 ml/hr of water mist supplied by compressed air), and flood (6 l/min of synthetic cutting fluid delivered as a water-based emulsion). Using a tool-work thermocouple to measure average tool-chip interface temperature, a decrease in temperature as the flow rate of fluid increased was measured. Cutting forces were largely constant during the experiment, indicating that the MQCF was primarily cooling and that temperature reductions observed were not due to any lubricating action. Increased coolant flow rate likely caused a larger temperature gradient in the chip, resulting in tightly coiled chips. Furthermore, cooling caused a significant reduction in contact length at the tool-chip interface, indicating that there is an indirect friction altering effect due to in-situ thermal changes at the tool-chip interface. With the aid of experimental measurements, the model calculated the temperature distribution at the interface between the chip and tool as well as discrete points in the chip and tool. The measured temperature decrease with coolant application could be used to solve for heff. The results from this research give insight into the minimum amount of cutting fluid needed to achieve a measurable temperature difference at the tool-chip interface. Additionally, this model can serve as a predictive machining tool to calculate temperature profiles for dry, flood, as well as minimized cutting fluid conditions

Heterologous Expression of a Membrane-Spanning Auxin Importer: Implications for Functional Analyses of Auxin Transporters

Biochemical studies of plant auxin transporters in vivo are made difficult by the presence of multiple auxin transporters and auxin-interacting proteins. Furthermore, the expression level of most such transporters in plants is likely to be too low for purification and downstream functional analysis. Heterologous expression systems should address both of these issues. We have examined a number of such systems for their efficiency in expressing AUX1 from Arabidopsis thaliana. We find that a eukaryotic system based upon infection of insect cells with recombinant baculovirus provides a high level, easily scalable expression system capable of delivering a functional assay for AUX1. Furthermore, a transient transfection system in mammalian cells enables localization of AUX1 and AUX1-mediated transport of auxin to be investigated. In contrast, we were unable to utilise P. pastoris or L. lactis expression systems to reliably express AUX1

When are the hands of healthcare workers positive for methicillin-resistant Staphylococcus aureus?

Hand hygiene is a key component in reducing infection. There are few reports on the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) on healthcare workers\u27 (HCWs\u27) hands. The aim of this study was to establish whether HCWs\u27 fingertips were contaminated with MRSA in a clinical hospital setting. The study was conducted in an acute tertiary referral hospital on four MRSA wards that were part of a larger research study on MRSA epidemiology and four other wards not included in the study. The fingertips from all categories of 523 HCWs were sampled on 822 occasions by the imprinting of fingertips on MRSA chromogenic agar plates. The type of hand hygiene agent used, if any, and the immediate prior activity of the HCW were recorded. Overall, 38/822 (5%) fingertips from 523 HCWs were MRSA-positive; 12/194 (6%) after clinical contact, 10/138 (10%) after contact with the patient\u27s environment and 15/346 (4%) after no specific contact. MRSA was recovered on 2/61 (3%) occasions after use of alcohol hand rub, 2/35 (6%) after 4% chlorhexidine detergent, 7/210 (3%) hand washing with soap and water, and 27/493 (5%) when no hand hygiene had been performed. MRSA was recovered from HCWs on seven of the eight wards. MRSA was more frequently present on fingertips on the four non-study wards vs the four MRSA study wards [18/250 (7%), 3/201 (1%), respectively; P\u3c=0.004]. The isolation of MRSA from HCWs\u27 fingertips, including after hand hygiene, indicates that more educational programmes are necessary to improve the quality of hand hygiene to prevent transmission of MRSA

Sheep Updates 2007 - part 4

This session covers eight papers from different authors: GRAZING 1. The impact of high dietary salt and its implications for the management of livestock grazing saline land, Dean Thomas, Dominique Blache, Dean Revell, Hayley Norman, Phil Vercoe, Zoey Durmic, Serina Digby, Di Mayberry, Megan Chadwick, Martin Sillence and David Masters, CRC for Plant-based Management of Dryland Salinity, Faculty of Natural & Agricultural Sciences, The University of Western Australia, WA. 2. Sustainable Grazing on Saline Lands - outcomes from the WA1 research project, H.C. Norman1,2, D.G. Masters1,2, R. Silberstein1,2, F. Byrne2,3, P.G.H. Nichols2,4, J. Young3, L. Atkins1,2, M.G. Wilmot1,2, A.J. Rintoul1,2, T. Lambert1,2, D.R. McClements2,4, P. Raper4, P. Ward1,2, C. Walton5 and T. York6 1CSIRO Centre for Environment and Life Sciences, Wembley, WA 2CRC for Plant-based Management of Dryland Salinity. 3School of Agricultural and Resource Economics, University of Western Australia. 4Department of Agriculture and Food WA. 5Condering Hills, Yealering. 6Anameka Farms, Tammin. MEAT QUALITY 3. Development of intramuscular fat in prime lambs, young sheep and beef cattle, David Pethick1, David Hopkins2 and Malcolm McPhee3,1School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA, 2NSW Department of Primary Industries, Cowra, NSW,3NSW Dept. of Primary Industries, University of New England, Armidale, NSW, 4. Importance of drinking water temperature for managing heat stress in sheep, Savage DB, Nolan JV, Godwin IR, Aoetpah A, Nguyen T, Baillie N and Lawler C University of New England, Armidale, NSW, Australia EWE MANAGEMENT TOOLS 5. E - sheep Management of Pregnant Merino Ewes and their Finishing Lambs, Ken GeentyA, John SmithA, Darryl SmithB, Tim DyallA and Grant UphillA A Sheep CRC and CSIRO Livestock Industries, Chiswick, NSW B Turretfield Research Station, SARDI, Roseworthy, SA 6. Is it important to manage ewes to CS targets? John Young, Farming Systems Analysis Service, Kojonup, WA MULESING 7. Mulesing accreditation - Vital for Wool\u27s Future, Dr Michael Paton, Department of Agriculture and Food WA, 8. Mulesing Alternatives, Jules Dorrian, Affiliation Project Manager Blowfly Control Australian Wool Inovatio

The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

Mitcham Urban Village Partnership Board -- a strategic proposal.

Mitcham town centre is in need of regeneration because of its deteriorated state, which is causing a feeling of discontent in the community. In our project, sponsored by the Environmental Services Department of Merton Council, we used case studies, interviews, and questionnaires to propose a Partnership Board for the town centre. This Partnership will work to improve the overall condition of Mitcham

Cloning and Biochemical Characterization of a Novel Carbendazim (Methyl-1H-Benzimidazol-2-ylcarbamate)-Hydrolyzing Esterase from the Newly Isolated Nocardioides sp. Strain SG-4G and Its Potential for Use in Enzymatic Bioremediation▿ †

A highly efficient carbendazim (methyl-1H-benzimidazol-2-ylcarbamate, or MBC)-mineralizing bacterium was isolated from enrichment cultures originating from MBC-contaminated soil samples. This bacterium, Nocardioides sp. strain SG-4G, hydrolyzed MBC to 2-aminobenzimidazole, which in turn was converted to the previously unknown metabolite 2-hydroxybenzimidazole. The initial steps of this novel metabolic pathway were confirmed by growth and enzyme assays and liquid chromatography-mass spectrometry (LC-MS) studies. The enzyme responsible for carrying out the first step was purified and subjected to N-terminal and internal peptide sequencing. The cognate gene, named mheI (for MBC-hydrolyzing enzyme), was cloned using a reverse genetics approach. The MheI enzyme was found to be a serine hydrolase of 242 amino acid residues. Its nearest known relative is an uncharacterized hypothetical protein with only 40% amino acid identity to it. Codon optimized mheI was heterologously expressed in Escherichia coli, and the His-tagged enzyme was purified and biochemically characterized. The enzyme has a Km and kcat of 6.1 μM and 170 min−1, respectively, for MBC. Radiation-killed, freeze-dried SG-4G cells showed strong and stable MBC detoxification activity suitable for use in enzymatic bioremediation applications