Modelling short channel mosfets for use in VLSI

In an investigation of metal oxide semiconductor field effect transistor (MOFSET) devices, a one-dimensional mathematical model of device dynamics was prepared, from which an accurate and computationally efficient drain current expression could be derived for subsequent parameter extraction. While a critical review revealed weaknesses in existing 1-D models (Pao-Sah, Pierret-Shields, Brews, and Van de Wiele), this new model in contrast was found to allow all the charge distributions to be continuous, to retain the inversion layer structure, and to include the contribution of current from the pinched-off part of the device. The model allows the source and drain to operate in different regimes. Numerical algorithms used for the evaluation of surface potentials in the various models are presented

The dynamics of collaborative resistance: negotiating the methodological incongruities of art, cultural theory, science and design.

This paper reflectively explores how the collaborative team behind in potēntia critically and creatively embraces the methodological dialectics that occur when trying to accommodate the different disciplinary approaches of art, cultural theory, science and design. Hosted by SymbioticA - The Centre of Excellence in the Biological Arts, The University of Western Australia, in potēntia is an example of multi-disciplinary collaborative art/science practice pioneered by SymbioticA. Negotiating aesthetics versus accuracy, risk versus rigor, experimentation versus speculation, and problematising versus problem solving, this paper reflexively discusses how cross-disciplinary collaboration, although fraught with friction also presents new and unique opportunities - professionally and personally - for unexpected creative discoveries to emerge

The role of residual beta-cell function on glycaemic and vascular outcomes at rest and post exercise in people with type 1 diabetes

PhD ThesisWithin patients with type 1 diabetes (T1D), residual ꞵ-cell function and endogenous insulin secretion occurs in a substantial number of individuals. The role this ꞵ-cell function plays in glycaemic control in individuals with T1D is currently not fully understood. This is especially true around exercise, where maintaining glycaemic control is challenging and a large inter-individual variation exists. Micro amounts of endogenous insulin secretion appears to offer some protection against vascular damage and diabetes complications. Endothelial progenitor cells (EPCs) are important for the repair and growth of blood vessels, with circulating numbers increased by exercise. However, the count of EPCs appear to be reduced in individuals with T1D. It is unknown whether residual ꞵ-cell function in individuals with T1D influences these circulating cells. Therefore, this thesis aimed to investigate the effects of residual ꞵ-cell function in individuals with T1D and its influence on glycaemic control under free-living conditions and after an acute bout of aerobic exercise, as well as on the count of circulating EPCs at rest and after exercise mobilisation. Chapter 3 demonstrated that under free-living conditions, increased endogenous insulin secretion was associated with improved continuous glucose monitoring measures, including increased time spent in euglycaemia. The results of Chapter 4 revealed that within a cohort who had comparable glycaemic control under free-living conditions, individuals with higher residual ꞵ-cell function displayed a substantially greater amount of time spent in euglycaemia in the hours following a bout of moderate intensity exercise compared to those with undetectable or lower endogenous insulin secretion. Lastly, Chapter 5 assessed the number of circulating EPCs at rest and after mobilisation with a bout of moderate intensity exercise. In comparison to matched non-diabetes controls, all markers of EPCs were lower in the T1D group, with some markers having attenuated mobilisation with exercise. Despite comparable resting counts, only the high residual ꞵ-cell function group had mobilisation of these cells with exercise within the T1D participants. In conclusion, the findings of this thesis demonstrate that residual ꞵ-cell function impacts upon individuals with longer duration T1D. Increased C-peptide secretion is associated with improved glycaemic control under free-living conditions and after an acute bout of exercise, as well as increasing the count of circulating EPCs that are mobilised with exercise

Lipid Extraction From Spirulina sp. and Schizochytrium sp. Using Supercritical CO2 With Methanol

Microalgae are one of the most promising feedstocks for biodiesel production due to their high lipid content and easy farming. However, the extraction of lipids from microalgae is energy intensive and costly and involves the use of toxic organic solvents. Compared with organic solvent extraction, supercritical CO2 (SCCO2) has demonstrated advantages through lower toxicity and no solvent-liquid separation. Due to the nonpolar nature of SCCO2, polar organic solvents such as methanol may need to be added as a modifier in order to increase the extraction ability of SCCO2. In this paper, pilot scale lipid extraction using SCCO2 was studied on two microalgae species: Spirulina sp. and Schizochytrium sp. For each species, SCCO2 extraction was conducted on 200 g of biomass for 6 h. Methanol was added as a cosolvent in the extraction process based on a volume ratio of 4%. The results showed that adding methanol in SCCO2 increased the lipid extraction yield significantly for both species. Under an operating pressure of 4000 psi, the lipid extraction yields for Spirulina sp. and Schizochytrium sp. were increased by 80% and 72%, respectively. It was also found that a stepwise addition of methanol was more effective than a one-time addition. In comparison with Soxhlet extraction using methylene chloride/methanol (2:1, v/v), the methanol-SCCO2 extraction demonstrated its high effectiveness for lipid extraction. In addition, the methanol-SCCO2 system showed a high lipid extraction yield after increasing biomass loading fivefold, indicating good potential for scaling up this method. Finally, a kinetic study of the SCCO2 extraction process was conducted, and the results showed that methanol concentration in SCCO2 has the strongest influence on the lipid extraction yield

Investigation of Electrolytic Flocculation for Microalga Scenedesmus sp Using Aluminum and Graphite Electrodes

Electrolytic flocculation using non-sacrificial electrodes with flocculants added was studied on harvesting Scenedesmus sp. In order to optimize the operating conditions of the electrolytic flocculation process and to quantify the amount of flocculants added, aluminum electrodes were first used in the process. It was found that under optimal conditions, the microalgae removal efficiency using aluminum electrodes could reach 98.5%, while 34.2 mg L-1 of aluminum ions were released during the process. Different metal electrodes were also studied, but high microalgae removal efficiency was witnessed only using aluminum electrodes, indicating the influence of the aluminum ion in flocculation. When non-sacrificial graphite electrodes were used in the electrolytic flocculation process, the corresponding amount of aluminum sulfate was added so that the aluminum ion concentration in water was also equal to 34.2 mg L-1. The result showed that the microalgae removal efficiency of graphite electrodes could reach above 90% after aluminum sulfate was added. In contrast, using graphite electrodes alone and using the metal salt alone only yielded 22.9% and 7.1% of microalgae removal efficiency, respectively. These results indicated that the presence of metal ions is necessary in the electrolytic flocculation process. The energy consumption of the process was found to be 0.3 kW h m-3 or 0.88 kW h kg-1, which is considered to be low energy consumption. The total cost of the process, including energy and chemicals, was found to be $ 0.21 m-3, proving a cost competitive method in microalgae harvesting

Psychiatric nurses’ views on criteria for psychiatric intensive care: acute and intensive care staff compared

Aim: To explore and investigate differences between the views of qualified nurses working in psychiatric intensive care units (PICUs) and acute care wards on which patients are appropriate for PICU care. Background: Previous research on the area of psychiatric intensive care highlights the great differences that exist in all aspects of service provision, from unit size and staffing levels to treatment approaches and physical environment. One of the most common areas of controversy is the type of client behaviour that warrants admission to the PICU. Method: Structured interviews of 100 qualified nursing staff (in the London area, England) working on either acute or PICU wards were used to gather data on appropriate and inappropriate referral to PICUs. Comments made during the course of the interviews were also collected and subjected to content analysis. Findings: There was evidence to support the hypothesis that acute ward staff considered patients suitable for PICU care at a lower level of risk than PICU staff thought appropriate. In comparison to acute ward nurses, those working in PICUs attended to a broader range of factors when considering suitability for admission to PICU. Appropriate reasons for transfer fell into five groups: risk to others; risk of intentional harm to self; risk of unintentional harm to self; therapeutic benefit from the PICU environment; and legitimate acute ward care problem. Inappropriate reasons for transfer fell into four groups: low risk to others and/or self; illegitimate acute admission care problems; patient belongs elsewhere; policy issues. Conclusion: The study opens up a range of issues not previously studied in relation to the use of PICUs and the intricate relationship of this use with the available acute care wards and other services. These findings and their implications for the care of acute and disturbed psychiatric patients are discussed

Biodegradation as natural fibre pre-treatment in composite manufacturing

Bacterial and fungal degradation of wheat straw has become intensively scrutinised in recent years because of the growing interest in procuring useful feedstocks and chemicals from lignocellulosic sources. Typically, after the extraction of valuable sugars and phenolics, significant quantities of solid biomass remain as waste. In this work, it has been shown that the leftover fermented wheat straw can be successfully used to reinforce epoxy resins, providing better strength properties compared to non-degraded straw. A 12% and a 22% increase in Young’s modulus and ultimate tensile strength respectively were observed for degraded wheat straw/epoxy composites compared to composites containing non-degraded straw. The improvement in mechanical strength is explained in terms of the structural and morphological transformations that occurred in the fibres during the fermentation process. The opportunity to use degraded natural fibres in the manufacturing of composites, in addition to the production of chemicals from lignocellulosic feedstocks, looks promising for improving biorefinery economics further