VictorJuiz/thesis huggingface dataset:
Carbon nanotube thin film electrodes and magneto-optical spectroscopy of perovskite single crystals and thin films

With each and every passing year, weather patterns seem to become less predictable and more chaotic due to changes to worldwide climate patterns. Greenhouse gas-free energy production is a boon to the aim of preventing further rises in global temperature increases. This thesis concerns itself with one major aspect of green energy, namely photovoltaics, and some materials with great potential for application in photovoltaics, namely single-walled carbon nanotubes (SWNT), and perovskites.
SWNT have been known for almost thirty years by now, but their intrinsic fondness of bundling up due to their 2pz-orbitals has to date prevented any large scale application of them. Functionalising of SWNT offers a solution to this problem, either by dispersing them with surfactants in water, or by polymer functionalisation. Here, the latter method was applied to the problem, and the efficacy of deposition from solvents more advantageous than water is shown, achieving values of transmission and sheet resistance close to the necessary values for application in solar cells.
Next, an inorganic contender for solar cell applications, Cs2AgBiBr6, is characterised by magneto-optical studies. With these, a direct and indirect gap are identified at 2.85 eV and 1.31eV. Moreover, a strongly Stokes shift influenced AgBi anti-site defect colour centre at 2.25 eV is shown to be part of a self-trapped exciton at low temperatures.
Thereafter, the optical properties between 1.4 K and 370 K in conjunction with room temperature x-ray diffraction measurements of MAPbI3 single crystals and thin films grown/annealed at different temperatures are used to explain the double emission structure visible in photo- luminescence and reflectance. A dynamic Rashba effect, likely due to spontaneous alignment of the methylammonium-ions, causes a direct and indirect gap, where the former dominates the surface and the latter dominates the bulk of the samples.
The remaining chapter is a study of the polaronic influence on the transitions observed for MAPbBr3 and MAPbI3. In comparison between high field, high energy, and low field, low energy, an almost two-fold difference in exciton binding energy, and an increase in effective mass can be observed due to exciton/lattice interactions in comparison to the established high field literature values. Interestingly, for both perovskites studied, single crystals show more favourable values, indicating that device application improvements could be possible by making thin films more single crystal-like.

Keywords: Reflectance
Polaron
PL
Rashba
Single Crystal
Transmission
Spectroscopy
Hybrid Perovskites
Functionalised Carbon Nanotubes
Advisor: Nicholas, R
Digital diplomacy in times of upheaval: how foreign ministries use Twitter during crises

The 21st-century has seen the emergence of an interconnected and multipolar world. Processes such as globalization complicate diplomatic crises and increase their frequency as regional conflicts have global ramifications and global events lead to regional confrontations. Amid this climate of perpetual and complex crises, diplomats will increasingly be called upon to practice crisis management. This thesis aims to explore whether the recent adoption of social media by ministries of foreign affairs (MFAs) influences the management of diplomatic crises. Thus, its guiding research question is- How do MFAs use digital tools in times of crises, and how can the use of these tools inform strategies to manage crises? The thesis postulates that during a crisis, MFAs will create frames through which digital publics can make sense of a crisis. The thesis further postulates that by evaluating the difference between two MFAs’ frames, one can measure the scope of relative disagreement between two governments and the likelihood of crisis escalation. To test these hypotheses, the thesis builds on the works of Erving Goffman and develops a 'frame distance' model that monitors the progression of a crisis in near-real time and identifies crisis pressure points at which diplomatic mediation may be most warranted or effective. Two case studies are used to evaluate the applicability of the frame distance model: the use of Twitter by the U.S. and Russian MFAs during the Crimean Crisis, and the use of Twitter by the Israeli MFA and the Hamas government during the 2014 Gaza war. An analysis of 2,012 tweets demonstrates that MFAs do in fact use Twitter to create real time frames through which a crisis may be understood. Moreover, the analysis demonstrates that by measuring the difference between two MFAs’ frames, one can identify crisis pressure points where diplomatic mediation may be most effective. Thus, the advent of online diplomacy enables diplomats to tailor diplomatic interventions to the offline progression of a given crisis, increasing the efficacy of diplomatic crisis management.

Keywords: social media
Crimean Crisis
digital diplomacy
crisis management
framing theory
2014 Gaza war
Advisor: Bjola, C
The consumption choices of "Generation Rent"

This thesis considers two questions: how does the aggregate quantity of consumption by young renters respond to house price shocks, and how has the increase in UK house prices changed how young renters allocate consumption between major expenditure categories. Results from a consumption life-cycle model show a positive relationship between the consumption growth by young renters and house prices. However, I conclude that this reflects a common factor such as income expectations independently determining both variables. I then estimate housing cross-price elasticities of demand for six major expenditure categories using a Quadratic Almost Ideal Demand System (QUAIDS) and UK household expenditure survey data. I identify differences in these elasticity estimates between higher and lower income young renter households, suggesting that rising house prices and lower homeownership rates is associated with increased financial stress for some households, but increased consumption of luxury goods by others. However, both higher and lower income rental households significantly increased the share of their budgets allocated to housing over the sample period, and experienced large declines in homeownership rates. These results highlight the importance of targeted housing affordability policies that consider these heterogeneities.

Keywords: Quadratic Almost Ideal Demand System
house prices
youth homeownership
demand system estimation
consumption
elasticities
housing
The impact of the Great War on French regionalism 1900-1924

Many Radical politicians believed that the regionalist programme, including regional assemblies, was a threat to the Third Republic. It implied a return to a traditional society, based on the provinces of the Ancien Régime and under the influence of the Catholic church. It might encourage separatism in areas with a different culture and language. This view set an interpretative framework for the historiography of French regionalism. Such a framework is open to question because it ignores a more pragmatic strand of regionalism which developed just before the Great War and which saw a shift of power to regional elites and their institutions as a way of modernising the French economy. This was a regionalism wholly compatible with Republican values.
The thesis is based on the regions of Lorraine and the Auvergne 1900–1924. It starts by examining the attachment to a regional identity and culture among regional elites in the pre-war years and during the war. It then shows how those elites used regional solidarity to mobilise their populations behind the war effort. This attachment to a region among the local elites explains their actions post-war. The thesis examines the emergence of practical economic regionalism in the work of the French school of geography, which inspired Clémentel, the Minister of Commerce, in his regional reform of 1918, creating new economic regions by grouping together chambers of commerce. The thesis examines the economic programmes adopted by chambers of commerce after the war and the motives behind infrastructure projects undertaken for the benefit of each region’s economy. It demonstrates the degree of initiative they showed independent of central government. In a final chapter this new pragmatic regionalism is compared with other regional discourses—preserving the cultural identities of the past, decentralisation and particularism, and fear of a German revival, particularly economically.

Keywords: First World War
Auvergne
France
regions
Lorraine
chambers of commerce
Advisor: Gregory, A
Hopkin, D
“Crossing the Channel to seek their future”: foreign female domestic servants in London 1881-1939

This thesis centres on international women migrants in London: how they crossed borders, navigated foreign spaces and experienced social and behavioural boundaries. Their stories are told through the lens of their economic status as domestic servants, by far the largest occupation absorbing women of all nationalities in London at this time. Accessing accounts of servant experiences has traditionally been perceived as challenging, yet as ‘aliens’ the women become more visible, both in society and in the records. What were the implications and consequences (positive or otherwise) of being foreign, female and employed in service during the period 1881–1939? And to what extent were they able to advantage of their otherness?
The thesis draws on an historical migration approach proposed by Pooley and Whyte in which both structural and individual evidence is bound together to offer new insights into both the system and the individuals it shaped. Using unique quantitative and qualitative sources permits an entirely new understanding of the female migrant experience, challenging our view of the male-only pioneering migrant, of foreign servants as luxury accessories and servants as young people engaged for short periods in a lifecycle occupation. In a bid to reverse the tendency in scholarship to represent female migrant labour as ‘victim’, the thesis incorporates servants’ experiences before, during and after domestic employment, that links London sculleries and suburban parlours with transnational migration.

Keywords: servants
British immigration
20th century
19th century
women
global migration
London
Advisor: Humphries, KJ
Synthesis and characterisation of mineral-derived and hybrid layered double hydroxides

This thesis discusses the development of atom efficient and scalable synthesis methods for the synthesis of industrially relevant layered double hydroxides (LDHs) using a green source of magnesium derived from a waste mineral. LDHs are introduced in Chapter 1 as compositionally flexible and versatile anionic clays. The structure of LDHs confers unique and interesting properties to these inorganic compounds and as such, LDHs have found application in a wide range of applications including environmental remediation and drug delivery. Naturally occurring LDHs are low in abundance but synthetic LDHs are facile to prepare and a variety of methods are available. The growing global demand for energy and resources calls for changes in the supply chain, so there is increasing interest in technologies and methods that are more environmentally friendly.
The analytical techniques and synthetic methods used are detailed in Chapter 2 ahead of the results and discussions in subsequent chapters. In Chapter 3, the mineral struvite, MgNH4PO4.6H2O, is investigated as an alternative starting material for magnesium based LDHs. Struvite was acquired from wastewater treatment plants (WWTPs) and compared with a synthetic struvite. To transform this underutilised resource into commercially relevant LDHs, the effect of temperature, pH and time were investigated. The properties and morphologies of the LDHs synthesised from struvite have been characterised in detail by a number of techniques including surface area analyses and electron microscopies.
Silica@LDH hybrid materials are investigated in Chapter 4. The effects of stirring speed and metal solution addition rate were systematically investigated and optimised. Strategies for core-shell synthesis using commercial silicas have also been developed to prepare high surface area silica@LDH hybrid materials that have been used as catalyst supports for ethylene polymerisation.
In Chapter 5, the thermal properties of the mineral-derived and hybrid LDH materials are studied to probe their suitability for carbon dioxide (CO2) capture. The LDHs were calcined to obtain the mixed oxide form of LDHs, layered double oxides (LDOs), and the properties of these calcined materials at different temperatures were studied. Selected LDOs were tested in CO2 adsorption experiments and their performance has been compared to that of LDOs from commercial and conventional LDHs.
Lastly, the findings of the works in this thesis are summarised in Chapter 6 and avenues for future investigations are also proposed. Supplementary information and data mentioned in the main thesis are included in the Appendices.

Keywords: Chemistry
Inorganic chemistry
Layered double hydroxide
Green chemistry
Industrial
Solid state chemistry
Characterisation
Synthesis
Mineral
Hybrid
Carbon dioxide
Advisor: O'Hare, D
Numerical analysis of implicitly constituted incompressible fluids: mixed formulations

We consider the numerical approximation of incompressible non-Newtonian flow by means of the finite element method, where the constitutive law is defined through an implicit relation G(S ,D(u)) = 0. The setting considered in this work captures models widely used in applications, such as the Bingham and the Carreau–Yasuda constitutive relations. Since in general it is not possible to solve for the shear stress S in the constitutive relation, the emphasis is placed on formulations treating the shear stress as a variable.
Under the assumption that the constitutive relation defines a monotone graph with r-growth, and that the finite element spaces satisfy appropriate inf-sup stability conditions, the first part of the thesis extends earlier results in the literature to provide a convergence result that guarantees that a subsequence of the numerical approximations converges weakly to a solution of the system, in the optimal range r > 2d/(d+2), where d is the spatial dimension. The qualitative nature of this convergence result is a consequence of the generality of the framework of implicitly constituted fluids, for which e.g. higher regularity estimates are not available. Computational examples show, nevertheless, that the numerical scheme considered exhibits the expected convergence rates, in the situations where these are available.
In the second part of the thesis we develop an augmented Lagrangian preconditioner for a stress-velocity-pressure formulation of the steady system. The preconditioner involves a specialised multigrid algorithm that makes use of a space decomposition that captures the kernel of the divergence operator, and non-standard intergrid transfer operators. Although the current theory for robust multigrid works only for symmetric and positive-definite systems (and thus does not apply to the systems considered in this thesis), the resulting preconditioner exhibits remarkable robustness properties.
In the final chapter of the thesis, the extension to the anisothermal case is carried out. We employ an implicit constitutive relation that allows for a temperature dependence of rheological parameters such as the viscosity and the yield stress, and provide convergence results for the unsteady forced convection system that takes the viscous dissipation term S : D (u) into account, and for the steady Oberbeck–Boussinesq approximation. For the latter an augmented Lagrangian preconditioner is also introduced; this preconditioner exhibits robust convergence behaviour when applied to the Navier–Stokes and power-law systems, including temperature-dependent viscosity, heat conductivity, and viscous dissipation.

Keywords: Multigrid methods
Finite element method
Non-Newtonian fluids
Advisor: Farrell, P
Suli, E
Digital privacy rights and the CLOUD Act regime

This thesis considers the impact of the new international data sharing ‘CLOUD Act regime’ on digital privacy rights. The first bilateral agreement of the regime, between the United States and United Kingdom, will enable UK law enforcement to directly enforce UK court orders for preservation, disclosure, and interception of electronic data against US service providers and vice versa. The CLOUD Act regime responds to long-standing concerns with the main mechanism for obtaining overseas data, mutual legal assistance (MLA). The US and UK claim that it will substantively improve on MLA while “respecting privacy and enhancing civil liberties”. This thesis interrogates that claim from a rights-based perspective, focusing on the primary constitutional mechanisms protecting digital privacy rights in each state, the Fourth Amendment to the US Constitution and Article 8 of the European Convention on Human Rights. Chapter 1 explains that emerging literature is divided: US commentators view the regime as neutral or rights-enhancing, while Europeans fear a significant reduction in rights. Chapter 2 details how the shift from MLA to the CLOUD Act regime will impact these rights for three affected classes: US nationals, UK nationals, and all others, ie third country nationals (TCNs). It shows that the contrasting views are each partly right and partly wrong. The CLOUD Act regime will be largely rights-enhancing for US and UK persons, but will further reduce the already limited protections provided to TCNs, due to existing interpretations of the Fourth Amendment and Article 8, which limit their application on the basis of nationality or geography, and thus exclude TCNs. Chapter 3 argues that the jurisdictional scope of these mechanisms should be reconceptualised for today’s digital world to protect TCNs’ digital privacy rights and therefore uphold the rights-enhancing aims of the CLOUD Act regime.

Keywords: Verdugo-Urquidez
Privacy
Cross-Border Data
Data Flows
CLOUD Act
Extraterritoriality
Human rights
Overseas Production Orders
Advisor: Butler, O
The dynamics of the South Pacific split jet in austral winter

The wintertime atmospheric circulation in the southern hemisphere is characterised by a zonally asymmetric, spiral-like pattern. This includes a strong jet over the Indian Ocean region, which bifurcates downstream into subtropical and polar front branches, known collectively as the South Pacific split jet. The location of the split jet, over Australia and New Zealand, means that this system exerts a considerable influence on the climate of these countries, while the jets also affect the climate of East Antarctica and southern South America.
In this thesis I investigate three major themes concerning the split jet. Firstly, I examine the surface boundary conditions which give rise to the observed split jet structure via a set of idealised, atmosphere-only model experiments. A particularly novel finding is that the presence of Antarctic orography plays a key role in shaping the split jet structure. Flattening Antarctica results in a weakened Indian Ocean jet and the destruction of the polar front branch of the split jet.
Secondly, I study the low frequency variability of the split jet, with a focus on the eddy-driven, polar front jet. I find that much of this variability can be captured by the Southern Annular Mode, while the presence of high latitude atmospheric blocking is closely correlated with equatorward jet shifts.
Finally, I evaluate the split jet and atmospheric blocking in CMIP5 models, before examining changes to the jet structure under the RCP8.5 climate change scenario. I find that circulation in the split jet region undergoes substantial changes in comparison to other regions, with zonal wind strengthening between the jets, causing the split jet to become less distinct. Following this, I demonstrate that these changes can largely be explained by considering the stationary wave response to changes in the subtropical Pacific.

Keywords: Jet streams
Atmospheric dynamics
Southern hemisphere
Advisor: Woollings, T
Bracegirdle, T
Noble gas sources, transport and groundwater interaction in sedimentary basins

The transport of subsurface fluids is an essential factor for the understanding of natural resource reservoirs and the assessment of environmental projects, such as carbon capture and storage and nuclear waste respiratory. Noble gases, due to their chemical inertness, are a useful suite of tracers for identifying and quantifying physical processes in the subsurface. In this study, numerical models were developed to characterise noble gas migration, aiming to identify hydrogeological events and to quantify crustal degassing processes. Samples from the Williston Basin were analysed for their noble gas concentration and isotopic composition. The excess 4He compared to the predicted in-situ production is evidence of cross-formational migration and noble gas flux from the ancient crystalline basement. Numerical simulations enable the quantification of apparent helium basement flux and the identification of hydrogeological units that have experienced 4He loss due to water disturbance. Noble gas samples from the Southwestern Ontario Basin were analysed. 4He and 40Ar basement fluxes are estimated with the transport model and are then used to construct basement flux maps. The maps identify flux anomalies in the basin, that are likely caused by compositional and permeability variations in the basement rock. Furthermore, differential equations are derived characterising the water-gas interaction under different degassing processes. Error-weighted, nonlinear inversion matrix models are computed for atmospheric noble gas isotopes to quantify the gas-water volume ratios and the excess Kr and Xe widely observed in sedimentary basins. The modelled results suggest that excess Kr and Xe are likely released from sedimentary grains. Finally, the formation of helium reservoirs in the Williston Basin is investigated and simulated with a one-dimensional diffusion-and-exsolution model, producing modelled results comparable to observations. This aids the understanding of nitrogen-rich helium reservoirs in ancient, stable intracratonic basins. Overall, this thesis explores noble gases applications, by combining measurements from natural systems with numerical and mathematical models, to identify and quantify fluid transport, gas exsolution, and crustal degassing.

Keywords: hydrogeology
noble gas
basement flux
helium
Advisor: Ballentine, C
Sherwood Lollar, B