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Chronic infection with hepatitis B virus is a global health issue, leading to liver cirrhosis and hepatocellular carcinoma that accounts for more than six hundred thousand deaths annually. Recent work has focused on the role of Natural killer (NK) cells in liver fibrosis in other contexts. In CHB, NK cells have been shown to play an anti-viral as well as an immunoregulatory role. Here we investigate the role of NK cells in the context of CHB-driven liver fibrosis, using primary hepatic stellate cells (HSC) isolated from healthy human liver margins. Our results demonstrate that NK cells from CHB patients have a highly variable and limited potential to kill hepatic stellate cells, which is increased in patients with progressive liver fibrosis, is further enhanced by interferon-alpha pre-activation in vitro and is abrogated by antiviral therapy with nucleos(t)ide inhibitors. We have explored the role of the death ligand TRAIL expressed on NK cells in inducing apoptosis of stellate cells that express high levels of the death-inducing receptor TRAIL-R2. We observed that blockade of TRAIL on the NK cells was only able to reduce killing of HSC in selected cases but not in the whole cohort, suggesting other levels of regulation. Moreover TRAIL ligand (SuperKillerTRAIL) treatment of primary HSC did not induce a degree of apoptosis commensurate with their high expression of the death-inducing receptor TRAIL-R2. We therefore probed the expression of the inhibitory receptors TRAIL-R3 and R4. We found expression of these receptors on primary human HSC both ex vivo and after in vitro culture. The level of expression of TRAIL-R4 showed a remarkably strong correlation with the susceptibility of primary HSC to undergo apoptosis. Furthermore, blockade of these inhibitory receptors rendered primary HSC more susceptible to apoptosis by SuperKillerTRAIL and by TRAIL-expressing NK cells. Our results are the first to demonstrate a functional role for TRAIL- R3 and -R4 in regulating susceptibility to apoptosis in primary cells. These novel findings will help us to define potential biomarkers and therapeutic targets for liver fibrosis.

This thesis is concerned with the study of British Indian internal policy between 1885 and 1898. The growth of English education, the Press, and swift means of communication brought the British Government into contact with developing Indian opinion, which called for a new approach. The difficulty of reconciling the principles of equality and of freedom of expression and association with the circumstances of an automatic foreign rule was fundamental. This study does not cover all important aspects of British policy. The addition of a few more topics, such as, the fiscal policy of the Government, more particularly the question of import duties on cotton goods, relations between the Supreme and Provincial Governments, and social legislation including tenancy reforms, would have certainly made the picture complete. It was, however, not possible to discuss them within the limits of a thesis. Even the topics included here have not been treated in all their aspects. The chapter on the problem of Indianisation, for instance, deals only with the Indian Civil Service in two aspects: the mode of recruitment and the scope of Indian employment. The present study is not concerned with organisational details. Statistics have been given only where absolutely necessary. In the examination of British policy of so recent a period as the present one, it is easy to exaggerate things either way. This study is, however, an attempt to view them in an objective and sympathetic manner.

This thesis studies the design, technological, economic and environmental performances of three low concentrating photovoltaic (LCPV) systems for building application. Non-tracked LCPV systems are identified as viable alternatives to the commercially available flat photovoltaic (PV) panels considering weather in the UK, where the diffuse component of solar radiation is predominant. The studied LCPV systems were comprised of a Compound Parabolic Concentrator (CPC), an Asymmetric Compound Parabolic Concentrator (ACPC) and a V-Trough concentrator. LCPV geometries were designed and simulated using the ray trace module in COMSOL Multiphysics to predict the optical efficiency at various levels of truncation whilst varying the angles of incidence. The geometric concentration ratios of LCPVs investigated were 1.53x, 1.46x, and 1.40x for ACPC, CPC, and V-Trough respectively. The ray trace simulations of the ACPC achieved the highest optical efficiency as compared to the other configurations studied. Furthermore, the thermal modelling of the ACPC concentrator when placed in an enclosure was performed to predict the cooling required to maintain the diurnal operating temperature of the module below the ambient temperature. For an irradiance of 945 W/m2, the average cell temperature of the ACPC module without the effect of cooling was found to be 84.85 °C. The predicted average cell temperature of the ACPC module at a cooling flowrate of 40 m3/h was 30.2 °C. Small scale prototypes of ACPC, CPC and V-Trough concentrators in conjunction with low cost solar cells such as mono-crystalline silicon cell (mono-C Si) and poly crystalline solar cell (poly-C Si) were manufactured and tested under OAI solar simulators. Measurements showed that ACPC concentrator with mono-C Si generated higher power as compared to the other configurations and flat PV panel. An analytical model was developed in this study to predict the annual energy output for the LCPV compared to an equivalent area of the flat PV panels. The measured optical efficiencies at various angles of incidence of the LCPV geometries were inputted to the model for realistic predictions. The analytical model is inputted with the weather data adopted from EnergyPlus weather datasets. Analytical modelling results showed that ACPC concentrator with mono crystalline silicon solar cells (mono-C Si) generated highest energy output per unit area of 177 kWh/m2 as compared to the other configurations. Full scale concentrators consisting of ACPC, CPC and V-Trough in conjunction with mono-C Si solar cells were manufactured, assembled and equipped for the deployment on the roof of a building at Brunel University London. The performances of the prototypes have been monitored every 15 min over 16 months and analyzed on an hourly, daily, and monthly basis. Performance parameters such as reference yield, array yield, performance ratio, electrical conversion efficiency and the generated energy output per unit area have been derived and presented. Payback periods have been estimated considering two scenarios. The scenarios consider LCPV module costs 15% and 35% higher than a flat PV module. Measurements have shown that the ACPC integrated LCPV achieved the highest annual optical efficiency generating the highest amount of electrical energy per unit cell area of 393 kWh/m2 compared to the CPC, V-Trough and conventional flat modules which produced 373 kWh/m2, 331 kWh/m2 and 306 kWh/m2 respectively. One particular conclusion of the study is that the ACPC based LCPVs achieved higher energy output in locations where the diffuse component of solar radiation is predominant as in the case of the UK. Consequently, ACPC based LCPV modules are recommended for the building retrofit in such locations.

Vacuum insulation panels currently offer the lowest thermal conductivity, ranging from 2 mW/m/K to 7 mW/m/K, a value four to ten times lower than the thermal conductivity of conventional insulation materials such as polyurethane foam and fibreglass. The major challenges facing the uptake of vacuum insulation panels in refrigerators is their high cost and limited manufacturing know-how. Fumed silica, one of the most common and successful core materials, costs around £6-8/kg. Expanded perlites come at one-tenth of the price and recent research on perlite and perlite-fumed silica composite based vacuum insulation panels has shown promising results in terms of the thermal performance. However, the scope of such studies is limited to experimental measurements performed on only one type of perlite. The knowledge on the effect of perlite specific properties like particle size, pore size, porosity combined with vacuum insulation specific properties including gas pressure and density on the thermal conductivity could unlock further potential of perlites to develop low cost vacuum insulation panels. The aim of this work was to experimentally develop alternative (to fumed silica) core materials based on perlite for vacuum insulation panels targeting cold chain equipment such as refrigerators and freezers, and predict the materials' thermal performance using a computer model developed specifically for this purpose. Seven different grades of perlite (P1-P7), eight different opacifiers along with fumed silica were researched to characterise their suitability for core materials in vacuum insulation panels. The study has been presented in a four phase process involving i) an extensive literature review concerning physics, material science and manufacturing of VIPs as well as modelling of cold chain equipment like refrigerators-freezers, vaccine boxes and fish boxes; ii) lab based characterisation of several powders (perlites, fumed silica, opacifiers) through various tests including Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), particle sizing, bulk density testing, thermal conductivity testing for their inherent properties like specific extinction, surface morphology and pore/particle sizes, loose powder thermal conductivity, composite powder thermal conductivity; iii) development of computer models in COMSOL and MATLAB to predict the thermal performance of VIPs developed with characterized core materials; iv) manufacturing and testing of VIPs made with characterized core materials, using a heat flow meter, and validating the developed models. Material characterisation showed that the given perlites could be mainly divided into two types: milled perlites, and expanded perlites. SEM images and pore size distribution analysis confirmed that in composites of fumed silica and perlites, small particles of fumed silica migrated into the on-particle pores of perlites, reducing the pore size. The effect of such migration was widely studied and is a novelty in this work. The computer model developed considering two different packing orders was able to calculate the bounds of conductive thermal conductivity (including solid, gaseous and coupling conductivity), and its variation with particle size, intra-particle pore size, porosity, sealing pressure and contact ratio. The radiative conductivity was obtained using the IR measurements and diffusion equation and its variation with composition and temperature was studied. The lowest kp=0 of a VIP was measured for a core composition of 85% fumed silica and 15% carbon black by mass (composition termed as FSCB). A VIP with core composition of 80% FSCB and 20% P1 returned a kp=0 of 1.2 times that of FSCB whereas a similar composite of P3 returned 1.5 times; both achieving a cost benefit of 18.5%. The measurements performed and computer model developed can be employed to produce bespoke perlites for most cost-effective thermal insulation systems.

Developing and studying flow boiling in micro channels has been done extensively over the last two decades in pursuit of effective cooling solutions for high power electronic devices. In addition, there is an urgent need for developing cost-effective sources of clean energy as the world faces challenges such as an ever-increasing energy demand and the global warming effect. Some of the renewable energy systems proposed require effective cooling solutions for the electronic controls employed, which again generate sizeable thermal loads over small areas. The current study comprises experimental tests for different test sections with three different aspect ratios of namely 0.56, 1 and 2 and a hydraulic diameter of 0.45 mm. Two different refrigerants were used, namely R134a and R1234yf (R1234yf is to replace the conventionally used R134a). The experiments were conducted under system pressures of 6, 7 and 8 bar, with four different mass fluxes tested at 50, 100, 200 and 300 kg/m2s. The maximum value of the wall heat flux reached was 277 kW/m2 and base heat flux up to 622.4 kW/m2. The exit vapour quality was up to 1. The main contribution of this study is the investigation of the effect of the aspect ratio, system pressure and fluid properties on the flow patterns, pressure drop and flow boiling heat transfer rates. The current study was performed at constant hydraulic diameter and constant surface roughness of the microchannels. Previous studies, which investigated the effect of the aspect ratio, system pressure and fluid properties did not necessarily keep to the same hydraulic diameter and surface roughness. The evaluation of the above effects for the same hydraulic diameter and surface roughness constitutes a unique contribution of the present study. Four types of flow patterns, namely bubbly, slug, churn and annular flow were captured at three different locations along the channel using a high-speed, high resolution camera. Also, the confined bubbles regime was identified. There is a significant effect of the fluid properties on the observed flow patterns. The existing maps in the published literature could not predict accurately the current experimental data, so a universal flow pattern map is still required. In this study, increasing wall heat flux led to an increase of the local flow boiling heat transfer coefficient. However, the mass flux has an insignificant effect on the local flow boiling heat transfer coefficient for all the current experimental results. The heat transfer rates depended on the channel aspect ratio. When the channel aspect ratio increased from 0.56 to 2, the local heat transfer coefficient was increased up to 27.7%. The effect of system pressure is insignificant for the operation system range of 6, 7 and 8 bar. The thermodynamic properties of the two fluids examined have a significant effect on the local heat transfer coefficient results. The current experimental data points were compared with existing correlations and a detailed discussion in included in the thesis. The experimental results demonstrated that the flow boiling pressure drop increased with decreasing channel aspect ratio. At the same time, the flow boiling pressure drop increased with reducing system pressure. The flow boiling pressure drop results of R134a were higher when compared with the R1234yf results. The current results were compared with existing pressure drop correlations with one correlation predicting our results with reasonable agreement. However, and similar to our findings on flow regime maps and heats transfer correlation, further research is required for a universal pressure drop correlation.

This thesis studies stationary, low concentration ratio, non-imaging reflective concentrators to generate power at a lower cost for applications in Building-Integrated Photovoltaics (BIPV). Stationary solar energy concentrators are a promising option for decreasing the price of photovoltaic electricity in BIPV. Two geometrically equivalent non-imaging concentrators parabolic V-trough and CPC are investigated routes to increasing the efficiency of solar cells employed in BIPVs. In this work V-trough and CPCs concentrators were modelled in COMSOL at various geometries and configurations. Each configuration was separately studied at various light angles of incidence. In addition, the effect of CPC truncation and V-trough side wall angle for BIPV implementation was also studied. The results showed big increases in angle of acceptance, reductions in height profile and V-trough-like characteristics past the original CPC design acceptance angles, with consequence in reducing material consumption for the manufacture of CPC and therefore reduction in the cost of the system. For ray tracing analysis a variety of direct and iterative solvers were tested and the generalized minimal residual method (GMRES) was used for 2D and 3D analysis of concentrators. A drop of performance was observed for both concentrators at increased light incidence angles; however, V-trough showed a better ability to dampen the loss as incidence angle increased. In terms of net concentration ratio, a truncated CPC at equal height shows a net concentration ratio of Copt=2.70 whilst V-trough hovered around Crnet=2.37−2.70 resulting in a net performance increase of 31% for CPC adoption. Results showed V-trough having lower concentration ratios but better performance at high angles of incidence compared to CPCs. Truncated CPCs showed equal optical efficiency to their full height parents but a lower concentration ratio due to a reduction in inlet aperture size. The modelled 50mm CPC concentrator designed for BIPV shows a greater overall concentrating performance, with significantly improved concentration up to the acceptance half angle, a small loss compared to the V-trough from the acceptance half angle to around 30° light incidence, and again an improvement over the V-trough from ~30° onwards. All truncated CPCs also show V-trough-like behaviour past their acceptance angles, making them suitable for BIPV incorporation. On the other hand, the V-trough concentrator showed better uniformity of flux distribution, this was especially pronounced at lower light angles of incidence. The experimental investigation was carried out on two candidates compound parabolic concentrator and a V-trough reflector on the optical and energy conversion characteristics. Two prototype LCPV systems based on dimensions of the selected concentrators have been manufactured and placed through outdoor testing conditions. The aim was to measure the solar radiation incident at the aperture and the PV cell surface using a pyranometer for times 10:00 to 14:00 equivalent to light incidence angles of -30° to +30°. The analysis of the experimental data showed good correlation with ray tracing simulations, showing similar behaviour with changing light angles of incidence. Experimental analysis showed that CPC had an overall 2.4% higher power output compared to V-trough concentrator. This agreed with the ray tracing studies. Although this was lower than the difference predicted by modelling analysis, this was put down to the non-uniformity of the concentrated light on the CPC absorber area and differences between the ideal and manufactured parabolic reflector. Based on these complexities some future work was recommended.

Buildings consume around half of the UK's total energy consumption and are responsible for almost 50% of UK's total carbon dioxide (CO2) emissions. Use of high thermal resistance insulation in buildings is critical to save the substantial amounts of space heating energy lost through building fabric. Conventional building insulation materials have higher thermal conductivity values ranging from 40 mWm-1K-1 (Glass fibre) - 26 mWm-1K-1 (Polyurethane foam) and require larger thicknesses to achieve stringent building regulation requirements which may not be feasible due to techno-economic constraints. Vacuum Insulation Panel (VIP) is a relatively new insulation for building applications that offers 5-8 times higher thermal resistance and can achieve significant space savings in buildings. VIPs are produced as a rigid panel comprising inner core board laminated in an outer high barrier envelope under evacuated conditions (< 5mbar). However, the main challenge for large scale acceptance of VIPs in building applications is their higher cost. VIPs have been shown to have an approximately 10 times longer payback compared to conventional EPS insulation due to their high initial cost. Expensive materials currently being used for VIP manufacturing such as fumed silica contribute to high cost of VIPs and it is critical to identify alternative low cost materials for VIP components to overcome the challenge of high cost. The aim of this thesis was to develop an alternative low cost material and investigate its suitability for use as VIP core. Expanded perlite, a low cost material was identified as a replacement of expensive fumed silica in a VIP core. Composite samples containing expanded perlite, fumed silica, silicon carbide (SiC) and polyester fibres were developed by dry mixing of the constituents in different mass ratios and their different properties were experimentally measured to identify optimum composition of composite. Gaseous thermal conductivity at different pressures was calculated from the pore size data obtained using Mercury Intrusion Porosimetry (MIP), gas adsorption and electron microscopy. Radiative conductivity of composite samples was measured using Fourier Transform Infrared (FTIR) to ascertain the opacifying effect of expanded perlite and opacifier (SiC). Centre of panel thermal conductivity of core boards of size 100mm x 100mm made of composite material at atmospheric pressure was measured by using a small guarded hot plate device. Average pore diameter values of expanded perlite decreased with the partial filling of fumed silica aggregates and was found to be in the range of 150-300 nm yielding lower gaseous conductivity values of 1.2-2.1 mWm-1K-1 at 100mbar and became negligible upon further decreasing pressures below 10 mbar. Core boards made of optimised composite containing 30% expanded perlite and 50% fumed silica along with SiC and polyester fibres was found to achieve centre of panel thermal conductivity of 28 mWm-1K-1 at atmospheric pressure and the average radiative conductivity of 0.67 mWm-1K-1 at 300K with its gaseous thermal conductivity at 1 mbar being 0.016 mWm-1K-1. According to the results of the thesis VIP prototypes consisting of core made with optimised composite consisting (50 mass% of fumed silica, 30 mass% of expanded perlite along with 8 mass% of fibre and 12 mass% of SiC) yielded centre of panel thermal conductivity of 7.4-7.6 mWm-1K-1 at pressure of 0.53-0.64 mbar. Opacifying properties of expanded perlite were observed and quantified. Expanded perlite reduced the radiative conductivity of the composite requiring smaller quantities of high density opacifiers such as SiC. For sample containing no expanded perlite, average radiative conductivity was calculated to be 1.37 mWm-1K-1 and radiative conductivity values decreased to 1.12 mWm-1K-1, 0.67 mWm-1K-1, 0.63 mWm-1K-1 and 0.50 mWm-1K-1 with mass ratio of expanded perlite 20%, 30%, 40% and 60% respectively. It was concluded that the solid conductivity of prototypes VIPs was 1.8-2 times higher compared to those of commercially available VIPs and is the main reason for higher centre of panel thermal conductivity.