Bradford Scholars is the University of Bradford online research archive. Access is free to anyone interested in research being conducted at Bradford. In the repository you will find a range of materials from journal articles and conference papers to research reports and theses.
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Real exchange rate and asymmetric shocks in the West African Monetary Zone (WAMZ)(2019)This paper examines real effective exchange rate (REER) responses to shocks in exchange rate determinants for the West African Monetary Zone (WAMZ) over the period 1980–2015. The analysis is based on a country-by-country VECM, and oil price, supply and demand shocks are identified using long run restrictions in a structural VAR model. We report significant differences in the response of REER to real oil price, productivity (supply) and demand preference shocks across these economies. In addition the relative contribution of these shocks to REER movements in the short and long run appears to be different across economies. Our findings suggest that the WAMZ countries are structurally different, and asymmetric shocks with inadequate adjustment mechanisms imply that a monetary union would be costly.
Towards Lattice-Boltzmann modelling of unconfined gas mixing in anaerobic digestion(2019-02-15)A novel Lattice-Boltzmann model to simulate gas mixing in anaerobic digestion is developed and described. For the first time, Euler–Lagrange multiphase, non-Newtonian and turbulence modelling are applied jontly with a novel hybrid boundary condition. The model is validated in a laboratory-scale framework and flow patterns are assessed through Particle Imaging Velocimetry (PIV) and innovative Positron-Emission Particle Tracking (PEPT). The model is shown to reproduce the experimental flow patterns with fidelity in both qualitative and quantitative terms. The model opens up a new approach to computational modelling of the complex multiphase flow in anaerobic digesters and offers specific advantages, such as computational efficiency, over an analogous Euler-Lagrange finite-volume computational fluid dynamics approach.
Synergistic toughening and compatibilisation effect of Poly(butylene succinate) in PLA/poly-caprolactone blends(2019-03)Binary and ternary blends of a polylactic acid matrix with polycaprolactone (PCL) and polybutylene succinate (PBS) were produced by twin screw extrusion, containing up to 30wt% loading. Mechanical, thermal and rheological characterisation techniques were used to quantify properties of the different blend formulations and miscibility was investigated using scanning electron microscopy. PCL is known to act as an impact modifier in PLA but to cause a corresponding reduction in strength. Results showed that addition of both PBS and PCL seperatly caused a reduction in melt viscosity, elastic modulus and tensile strength, but an increase in impact strength and strain at break. Analysis of morphology suggested that immiscibility was evident, particularly at higher PCL and PBS loadings. Results indicated that incorporation of a small loading of PBS had a synergistic effect on the PLA-PCL blend properties. Miscibility was improved and enhanced mechanical properties were observed for a ternary blend containing 5wt% of both PBS and PCL compared to blends containing 10% of each polymer alone.
Highly-ordered onion micelles made from amphiphilic highly-branched copolymers(2018)Uniform onion micelles formed from up to ten nano-structured polymer layers were produced by the aqueous self-assembly of highly-branched copolymers. Highly-branched poly(alkyl methacrylate)s were chain extended with poly(acrylic acid) in a two-step reversible addition–fragmentation chain transfer-self-condensing vinyl polymerization (RAFT-SCVP) in solution. The resulting polymers were dispersed into water from oxolane (THF) using a self-organized precipitation-like method and the self-assembled particles were studied by phase-analysis light scattering, small-angle neutron scattering, and electron microscopy techniques. The relative hydrophobicity of the blocks was varied by changing the alkyl methacrylate (methyl, butyl, or lauryl) and this was found to affect the morphology of the particles. Only the poly(butyl methacrylate)-containing macromolecule formed an onion micelle structure. The formation of this morphology was observed to depend on: the evaporation of the good solvent (THF) during the self assembly process causing kinetic trapping of structures; the pH of the aqueous phase; and also on the ratio of hydrophobic to hydrophilic segments within the copolymer. The lamellar structure could be removed by annealing the dispersion above the glass transition temperature of the poly(butyl methacrylate). To exemplify how these onion micelles can be used to encapsulate and release an active compound, a dye, rhodamine B (Rh B), was encapsulated and released. The release behaviour was dependent on the morphology of the particles. Particles formed containing the poly(methyl methacrylate) or poly (lauryl methacrylate) core did not form onions and although these materials absorbed Rh B, it was continuously released at room temperature. On the other hand, the lamellar structure formed from branchpoly( butyl methacrylate)-[poly(butyl methacrylate)-block-poly(acrylic acid)] allowed for encapsulation of approximately 45% of the dye, without release, until heating disrupted the lamellar structure.
Consumption of salt rich products: impact of the UK reduced salt campaign(2019)This paper uses a leading UK supermarket’s loyalty card database to assess the effectiveness and impact of the 2004 UK reduced salt campaign. We present an econometric analysis of purchase data to assess the effectiveness of the Food Standard Agency’s (FSA) ‘reduced salt campaign’. We adopt a general approach to determining structural breaks in the time series of purchase data, using unit root tests whereby structural breaks are endogenously determined from the data. We find only limited evidence supporting the effectiveness of the FSA’s reduced salt campaign. Our results support existing findings in the literature that have used alternative methodologies to examine the impact of information campaigns on consumer choice of products with high salt content.