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Copyright © 2018 The Authors. Increasing column/tubing aspect ratio has been shown in a feasibility study to improve column efficiency when operating in reversed phase mode. This paper contains a thorough investigation on how increases in mobile phase flow and centrifugal force field affect stationary phase retention and column efficiency (as measured by the resolution between adjacent peaks) for columns wound with rectilinear tubing of different aspect ratio. The study uses a Mini CCC instrument operating from 1500 to 2100 rpm (126–246 g) to compare three columns with the same cross-sectional area but different aspect ratio – rectangular horizontal (force field perpendicular to the flat side – aspect ratio 3.125); square (aspect ratio 1.0) and rectangular vertical (flat side parallel with force field – aspect ratio 0.32). Columns are compared by measuring stationary phase retention, resolution and normalized resolution for 3 different mobile phase flow rates 2, 4 and 8 ml/min in both normal phase and reversed phase modes. The results with rectilinear tubing are compared to conventional circular tubing with the same cross-sectional area. The results show that resolution increases with aspect ratio and that at the highest aspect ratio the highest flow rate can maintain a high efficiency only if the highest g-field of 246 g is used. When comparing the rectangular horizontal tubing which gave the best results with conventional circular tubing with the same cross-sectional area a 45% improvement was found in reversed phase mode and a 51% improvement in normal phase mode over the conventional circular cross-section tubing. In other words, a rectangular horizontally wound bobbin with half the length of tubing can achieve the same result as a circular one. These are very significant results for halving separation times analytically or enabling designers to produce new instruments of the same capacity with a much-reduced size. National Science Foundation of China (NSFC)

© 2009 IUPAC Countercurrent chromatography (CCC) is a generic term covering all forms of liquid-liquid chromatography that use a support-free liquid stationary phase held in place by a simple centrifugal or complex centrifugal force field. Biphasic liquid systems are used with one liquid phase being the stationary phase and the other being the mobile phase. Although initiated almost 30 years ago, CCC lacked reliable columns. This is changing now, and the newly designed centrifuges appearing on the market make excellent CCC columns. This review focuses on the advantages of a liquid stationary phase and addresses the chromatographic theory of CCC. The main difference with classical liquid chromatography (LC) is the variable volume of the stationary phase. There are mainly two different ways to obtain a liquid stationary phase using centrifugal forces, the hydrostatic way and the hydrodynamic way. These two kinds of CCC columns are described and compared. The reported applications of CCC in analytical chemistry and comparison with other separation and enrichment methods show that the technique can be successfully used in the analysis of plants and other natural products, for the separation of biochemicals and pharmaceuticals, for the separation of alkaloids from medical herbs, in food analysis, etc. On the basis of the studies of the last two decades, recommendations are also given for the application of CCC in trace inorganic analysis and in radioanalytical chemistry.

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. Structured to help readers from a range of disciplines, the thesis looks at the creation of opportunities for participation in adventure sport, specifically the development of a postural support for intermediate level performers with spinal cord injury in sea kayaking. The research has shown that it is possible to increase the performance level of disabled athletes in paddle sport through the development of appropriate adaptive equipment, which in turn promotes inclusion and the broadening of opportunities. This research project takes place against a backdrop of national events and developments; notably, changes in UK legislation to do with disability access (DDA 1995), and developments in legislation to do with outdoor safety. The research also takes place against a backdrop of national campaigns, such as the ‘Campaign for Adventure’, and an increasing number of drives to make the UK’s population more active. The broad-based multidisciplinary approach is in line with reported priorities in international disability sport research, while encompassing paddlesport specific criteria. The research takes the approach of design research to develop the product. Initially the reported studies evaluate the design process utilising desk-based research. They then proceed to utilise design methodology in field-based short and longer expedition settings. The design process utilises existing user-centred staged design approaches to explore methods for wider application. The findings reveal that the development of opportunities in adventure sport with disabled people involves engaging with a social mess. The action of problem definition and resolution can be termed in this paradigm as a wicked problem, being that is does not have one clear solution. The information needing to be exchanged in the problem resolution can be considered as sticky, being that the research process takes place in a specialised arena characterised by sparse resources and with a multidisciplinary team. The research has informed the creation of twelve tools to support those practitioners involved in this area. Used from the bottom up or top down, they provide a common language between the participant, coach, therapist and researcher to help educate and inspire each person to understand the true nature of the problem, improve the shared understanding within the team, and thereby reducing the stickiness of the information. The effect on the development of new equipment is to improve focus and user participation, so making it easier to work within the social mess. A new postural support was designed for use by intermediate level sea kayakers with spinal cord injury, the design of which is given in study 9, which is evaluated in study 10. The study suggests that future work in this area should focus on the coordination of sport science support, further exploration of the link between design research and social change, explore the validity of the tools across a broader population, and further develop the design so that the new equipment can be of benefit to the broader population.

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. This thesis deals with the mechanics of the Intra-Aortic Balloon Pump (IABP), the most widely used temporary cardiac assist device, whose beneficial action is based on the principle of counterpulsation. The investigation is carried out in vitro in increasingly more realistic setups, including a mock circulatory system with physiological distribution of peripheral resistance and compliance in which IABP counterpulsation was simulated. Pressure and flow measurements show the effect of variables such as intra-luminal pressure, angle and aortic compliance on balloon hemodynamics. These data are complemented by results on the duration of balloon inflation and deflation obtained by means of high-speed camera visualisation. Furthermore, wave intensity analysis is carried out and it is identified as a possible alternative method for the assessment of IABP performance. This work includes two prototypes of intra-aortic balloons of novel shape with the balloon chamber tapering both from and toward the balloon tip. In clinical terms, with reference to the semi-recumbent position in which patients assisted with the IABP are nursed in the intensive care unit, the results presented in this thesis indicate that operating the balloon at an angle compromises the benefit of counterpulsation when assessed in vitro.

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. 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.