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Molecular-level removal of proteinaceous contamination from model surfaces and biomedical device materials by air plasma treatment
No full textEstablished methods for cleaning and sterilising biomedical devices may achieve removal of bioburden only at the macroscopic level while leaving behind molecular levels of contamination (mainly proteinaceous). This is of particular concern if the residue might contain prions. We investigated at the molecular level the removal of model and real-life proteinaceous contamination from model and practical surfaces by air plasma (ionised air) treatment. The surface-sensitive technique of X-ray photoelectron spectroscopy (XPS) was used to assess the removal of proteinaceous contamination, with the nitrogen (N1s) photoelectron signal as its marker. Model proteinaceous contamination (bovine serum albumin) adsorbed on to a model surface (silicon wafer) and the residual proteinaceous contamination resulting from incubating surgical stainless steel (a practical biomaterial) in whole human blood exhibited strong N1s signals [16.8 and 18.5 atomic percent (at.%), respectively] after thorough washing. After 5 min air plasma treatment, XPS detected no nitrogen on the sample surfaces, indicating complete removal of proteinaceous contamination, down to the estimated XPS detection limit 10 ng/cm2. Applying the same plasma treatment, the 7.7 at.% nitrogen observed on a clinically cleaned dental bur was reduced to a level reflective of new, as-received burs. Contact angle measurements and atomic force microscopy also indicated complete molecular-level removal of the proteinaceous contamination upon air plasma treatment. This study demonstrates the effectiveness of air plasma treatment for removing proteinaceous contamination from both model and practical surfaces and offers a method for ensuring that no molecular residual contamination such as prions is transferred upon re-use of surgical and dental instruments.
The Dawson Hill Member of the Grindstone Range Sandstone in the Flinders Ranges, South Australia
No full textA water-centred framework to assess the effects of salinity on the growth and yield of wheat and barley
No full textWe used a water-centred framework (yield = transpiration × transpiration efficiency × harvest index) to investigate the effect of soil salinity on growth and yield of wheat and barley. Our working hypothesis is that salinity reduces transpiration proportionally more than transpiration efficiency. We established a glasshouse experiment with the factorial combination of four varieties (wheat: Janz, Krichauff; barley: Mundah, Keel) and three soil treatments: a control with no NaCl added, and NaCl added to achieve soil EC1:5 0.75 dS m−1 and 1.5 dS m−1. Pot-grown plants were watered to weight to determine transpiration and shoot dry matter was determined using a non-destructive image analysis system. Consistent with our hypothesis, salinity reduced transpiration (30–60%) proportionally more than transpiration efficiency (0–35%); transpiration accounted for 90% of the variation in shoot growth across varieties and treatments. Against this pattern, there were time- and variety-dependent responses. The rate of leaf appearance and the transpiration efficiency of Janz, Krichauff and Keel showed a two-stage response to salinity. In stage 1, salt-stressed plants maintained rate of leaf appearance and transpiration efficiency close to or slightly below those of the controls. After a clear break point where the slope changed, stage 2 was characterised by a substantial reduction in both traits. Stage 2 was not evident in salt-stressed Mundah, which maintained a relatively high rate of leaf appearance and transpiration efficiency. Across species, harvest index increased from 0.40 in controls to 0.47 at 0.75 dS m−1. Harvest index of plants grown at 1.5 dS m−1 was unaffected in wheat, and was reduced in barley. We propose that an understanding of the effect of salinity on crop development, growth and yield requires integration of low-level traits in a framework of resource capture, resource-use efficiency and plant allocation. Osmotic stress tolerance, Na+ exclusion, and tissue tolerance to accumulated Na+ would improve yield of salt-stressed crops to the extent that these traits contribute to the maintenance of water uptake and harvest index.
Relationships, participation and support : necessary components for inclusive learning environments and (re)engaging learners
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Development of multifunctional urban land uses using water sensitive urban design
No full textThere are often competing demands for the ever-decreasing available land space in our towns and cities. In many cities, this has led to new transport infrastructure going underground. However, most of our landspaces are still monofunctional, including the areas on which we currently park our cars. Not only is this not sustainable, into the future it will not be economically viable. This chapter explores the concept of multifunctional urban land use, with a specific emphasis on water-sensitive urban design (WSUD). Instead of dedicating areas of land to a single land use, such as water conservation, flood control, water-quality treatment or public amenity, the possibility of using the same land to serve all these purposes is explored through comparative case studies. A multifunctional approach to urban land use is presented thorugh which habitat connections, flood storage, water reuse and social amenity are all integrated into the same land corridors. This approach can be economically competitive, as it could potentially release flood prone fringe areas for development, which in turn could provide the economic driver to achieve higher-level outcomes, such as the enhancement of urban ecology.
