Thesis (M. Phil.)--Brunel University. / Includes bibliographical references (p. 208-213).

Thesis (M. Phil.)--Brunel University. / Includes bibliographical references (p. 208-213).

Physiotherapy for people with stroke has been found to be beneficial but details of the most effective interventions are unclear. Further development of the evidence base for stroke physiotherapy is limited by a lack of clinical practice models, sensitive clinically based outcome measures and effective stratification techniques to characterise homogenous groups of subjects. These issues are addressed here with regard to balance and posture. These aspects were chosen because they form a cornerstone of stroke physiotherapy as they are thought essential for the rehabilitation of functional activities. A systematic review of assessment methods in the literature revealed a lack of measurement tools which met the utility criteria: reliability, validity, sensitivity to short-term change, suitability for a wide range of abilities, ease of use and suitability for different settings. This prompted the development of a new measurement tool. Firstly, a model of the clinical assessment process was developed using an adapted focus group method with neurological physiotherapists. This informed the content of a new measurement tool which combined an ordinal scale with functional performance tests- the Brunel Balance Assessment. The tool was evaluated in a series of studies involving 92 stroke patients. It was hierarchical (coefficient of reproducibility= 0.99, coefficient of scalability = 0.69), reliable (100% agreement) and valid as a measure of balance disability (r=0.58-0.97). The psychometric properties of the individual functional performance tests were also tested and found to be reliable (ICCs =0.88-1) and valid (r=0.32-0.63). Measurement error ranged 0-40% and the minimum change needed to detect true clinical change was calculated for each test. Balance disability, measured with the Brunel Balance Assessment, is heterogeneous with sitting, standing and stepping balance forming distinct levels of ability (p<0.027). Consequently, the BBA could be used to stratify people with stroke according to balance ability. Weakness, sensation and age were significant independent contributors to balance disability (r2=82.7%). Balance ability was a strong contributor to independence in ADL (p<0.0001). The findings of this thesis address the issues that have limited research into stroke physiotherapy with regard to balance disability. In relation to clinical practice, a robust measurement and stratification tool has been developed.

A large number of commercial and some novel Brunel synthesised surfactants have been studied with a view to their potential usefulness for enhanced oil recovery (EOR) application. Ethoxylated phenols and their sulphonated derivatives were given especially high priority. The surfactants were well-characterised in order to understand their EOR potential. High pressure liquid chromatography, mass spectrometry, Raman spectrometry, nuclear magnetic resonance spectrometry and other quantitative techniques were used. Aspects of their behaviour (as single components and as blends with co-surfactants and co-solvents) which have been considered in terms of: (i) phase behaviour with brine and hydrocarbons (ii) adsorption onto various oxide surfaces (iii) interfacial properties such as surface tension, wetting, contact angles and viscosity (iv) stability Three different blends using sulphonated surfactants which: (i) produce a microeinulsion which is stable to high salinity brines over a large temperature range (ii) exhibit low adsorption onto reservoir rock (iii) interfacial tension as low as 10-2mNm-1 have been subsequently optimised. Core flooding tests carried out under reservoir conditions produced an additional 20% of the original-oil-in-place.

The difficulties encountered in quantitative analysis by gas chromatography are discussed, with particular reference to detection systems. The properties of an ideal detector for quantitative analysis are listed. A description is given of the mode of operation of detectors for gas chromatography, and the extent to which they are suitable for quantitative work is assessed. It was concluded that no one detector possessed all the properties required or an ideal detector. In particular a qualitative knowledge of the sample for analysis was required by all detectors; and calibration was required by the majority of detectors. The extent to which the Brunel mass detector overcomes these limitations was assessed. It is shown that the response of the mass detector depends solely on weight changes caused by adsorption of materials eluted from the chromatographic column thus completely eliminating the need for calibration and qualitative information. The response of the detector is integral, so that the problems associated with peak area measurement do not arise. The sensitivity of the detector is of a similar order to conventional hot wire detectors. The detector gave a quantitative response to all materials analysed, covering a wide boiling range: the upper limit was determined by the maximum column operating temperature, and the lower limit by the extent to which the detector was cooled. The detector responded quantitatively to water. At room temperature the detector responded on a qualitative basis to organic and inorganic gases. The detector was used for the calibration of other detector, and was operated in conjunction with the Martin gas density balance to determine the molecular weights of eluted materials.

Countercurrent chromatography (CCC) is an advanced liquid-liquid extraction technique that purifies chemical components from complex mixtures. The Brunel CCC' is a J-type centrifuge based upon this technique. This machine can process 5g quantities of sample every 5 hours [Sutherland 1998]. To process 1 tonne of sample per year would require 200 Brunel CCCs, which is not practical as an industrial process. A practical alternative is to use one machine with 200 times the processing capability. To construct such a machine requires a greater understanding of the stationary phase retention inside a coil (column) and the column efficiency (mass transfer between the mobile and stationary phases). This thesis contains research into stationary phase retention. A hypothesis that all J-type centrifuges act as constant pressure drop pumps is proposed. This hypothesis combined with the Hagan-Poiseuille equation for laminar flow produces a theoretical basis for plotting the stationary phase retention against the square root of the mobile phase flow rate as proposed by Du et al [1999]. Supporting experimental evidence is presented showing that the mobile phase flows in a laminar manner and that the pressure drop across a coil is constant for a given set of operating conditions. It is shown that the pressure drop is the same in both normal and reverse phase modes if specific conditions are met. The pressure drop is shown to be independent of tubing bore for helical coils provided that the same helical pitch is used. The experimental results also show how the pressure drop varies with the phase system and rotational speed. Hopefully this is a significant advance in predicting the stationary phase retention of industrial scale J-type centrifuges.