VictorJuiz/thesis huggingface dataset:
Synthesis, structure and magnetism of mixed-anion solids

This thesis investigates the structure-property relationships in the series of mixed-anion solids Ae2MO2X2Ch2 (Ae = Sr, Ba; M = Co, Ni; X = Cu, Ag; Ch = S, Se), Ae3-xAe’xFe2O5Cu2Ch2 (Ae = Ba, Sr, Ca; Ch = S, Se), and Sr2NiO2Cl2.
A spin-state crossover in the solid solution Sr2NiO2Cu2(Se1-xSx)2 has been observed as a function of composition, with two-dimensional magnetic correlations observed for one sample of high S-content before all sign of magnetic scattering is lost which is accompanied by a clear structural signal suggesting a change from high- to low-spin.
The novel, lithiated Ae2CoO2X2-xLixCh2 (Ae = Sr, Ba; X = Cu, Ag; Ch = S, Se) phases have been synthesised and have similar magnetic ordering to that seen in their non-lithiated analogues. These materials have localised Co2+ moments greater than the spin-only predicted 3 uB, suggesting a large orbital contribution to the moment which is discussed further within the chapter.
Ba3-xSrxFe2O5Cu2Ch2 (x = 1, 2; Ch = S, Se) and BaCa2Fe2O5Cu2S2 both show distinct cation ordering between a larger 12-coordinate site and 8-coordinate site and order antiferromagnetically with moments tilted away from the basal plane as opposed to within the plane when there is only one alkaline earth metal present.

Keywords: oxide chalcogenides
oxide halide
magnetism
solid-state chemistry
structure-property relationships
mixed-anion solids
Advisor: Clarke, S
Some nuclear physics aspects of the r-process nucleosynthesis

Two aspects of the nuclear physics involved in calculations of the rapid neutron capture process (or r-process) are studied in an attempt to put the nucleosynthesis predictions on safer and sounder grounds. In considering the first aspect, we investigate the influence of nuclear mass models on the r-abundance distribution in the framework of the standard r-process model. Here the first r-process calculations, making use of a non-droplet type mass formulae, are performed. The r-abundance distribution obtained with the mass table based on the microscopic Extended Thomas-Fermi plus Strutinsky Integral method shows significant differences from the one using a droplet mass formula. The impact of the nuclear mass model on the final r-abundance profile is analysed in detail.
With the second aspect, another quantity of fundamental importance for the r-process calculations, the nuclear level density, is examined. In the framework of the statistical model, the analytical approximation to the spin-dependent level density is improved by introducing in a new way the shell and pairing effects. The semi-classical approximation to the single-particle state density is used to describe the influence of the nuclear shell structure on the energy dependence as well as on the spin distribution of the level density. To take the pairing effects on the level density into account, simple and accurate analytical expressions are derived from the BCS formulation. The new analytical level density formula appears to be in close agreement with both numerical shell-model calculations and experimental data. To prove the reliability of the adopted semi-classical shell description, a new formulation of the ground-state shell correction energy and of the ground-state pairing gaps is proposed and shown to give a good fit to the experimental data.

Advisor: Hodgson, P
Surface forces and structures in complex electrolytes

Electrolytes, environments in which ions are free to move, are found throughout the natural and the human-centred world. The biochemistry that allows for life, alongside many of the innovations that make modern life so convenient, rely on the physical chemistry of these substances. Despite this, the behaviours of many complex and high concentration electrolytes are relatively poorly understood. This thesis investigates the forces and structures present in three examples of complex, high concentration electrolytes in order to better the understanding of these fascinating systems.
First, we present measurements of surface forces present in water-in-salt electrolytes, high concentration aqueous electrolytes with potential applications in next generation energy storage devices. We find evidence for a layered structure of aqueous and non-aqueous domains within the confined electrolyte films. These domains are maintained in the bulk liquid, and our analysis of the clustering of the domains suggests consequences for the mechanism of ion transport in water-in-salt electrolytes. We also studied ionic liquids, liquid electrolytes consisting solely of ions. We show that different layered structures can form in ionic liquids confined between surfaces, where the structure adopted depends on the nature of the ions. On studying mixtures of ionic liquids that form different interfacial structures, we find that the mathematical expressions describing the mixtures can be written as a linear combination of the terms describing pure ionic liquids. These results have important implications for the interpretation of correlation lengths within liquid mixtures, and for the optimisation of surface properties by creating liquid mixtures. Finally, we investigate the modifications of surface forces that occur in the presence of the high-concentration protein denaturant guanidinium chloride. We find varying behaviour across a broad concentration range that suggests strong time and concentration dependence in the action of guanidinium chloride at protein surfaces.
Together, the results of this thesis highlight the complexities of high concentration and poorly understood electrolyte solutions, and shed light on their interactions and behaviours. This work will be important in fully understanding the role these complex systems play, both in the devices and conveniences that allow modern life to function, and in the complex chemistries that govern life at a molecular level.

Keywords: water-in-salt electrolytes
guanidinium chloride
surface force balance
neutron scattering
ionic liquids
surface forces
denaturants
surfaces
Advisor: Perkin, S
Soft chemistry of layered chalcogenides

This thesis reports the synthesis and characterisation of several new layered chalcogenides. Low temperature intercalation methods have been used to synthesise new metastable materials which retain the general structure of their precursors, but modify their properties.
Chapters 3 and 4 focus on the intercalation chemistry of excitonic insulator candidate Ta2NiSe5 and structurally related compound Ta2NiSe7. Several species can be intercalated into Ta2NiSe5, all cause significant, but similar, rearrangement of the Ta-Ni-Se layers. Conversely, Li intercalation into Ta2NiSe7 is found to be topotactic in nature and highly reversible. High resolution synchrotron XRD data reveals two distinct phases are formed depending on Li content, and neutron diffraction is used to characterise each phase. Electrochemical studies show continuous filling of the Li sites, and are presented as a comparison to the chemical synthesis.
Chapters 5 and 6 of this work explores the manipulation of layered near room temperature ferromagnetic compounds Fe3GeTe2 and Fe5GeTe2, by insertion of Li(NH2) or K into the interlayer spacing. Intercalation into Fe3GeTe2 results in rearrangement of the Fe-Ge-Te layers and an increase in the Curie temperature by approximately 25 K. In contrast, intercalation into Fe5GeTe2 results in no layer rearrangement and very little change to the ferromagnetic behaviour of Fe5GeTe2. The magnetic properties are characterised through SQUID magnetometry, neutron diffraction and Mössbauer spectroscopy on polycrystalline samples.

Keywords: layered compounds
magnetometry
intercalation
x-ray diffraction
chalcogenides
Advisor: Clarke, S
Pharmacological and structural studies on the hedgehog pathway receptor smoothened

The Frizzled-class G protein-coupled receptor Smoothened (SMO) is an essential component of the Hedgehog (HH) signalling pathway, which is of paramount importance to developmental processes of bilaterians. Dysregulation of HH signalling has been implicated in multiple pathophysiological processes in adult organisms, such as cancer development. SMO is targeted by multiple anti-cancer drugs, but resistance mutations were reported to decrease inhibitor potency and adverse events force medication discontinuation. While structural and functional studies have furthered our understanding of how SMO is regulated, details of SMO activation mechanisms and the interplay between the multiple SMO ligand-binding sites remain to be further clarified. Furthermore, there is limited information on the mechanisms of downstream signal transduction of vertebrate SMO, which most likely involve the G protein-coupled receptor kinase 2 (GRK2). This thesis describes the work we conducted to contribute to answering these questions, and to the development of next-generation SMO inhibitors. We optimised sample preparation to determine high-resolution structures of inactive SMO from human and fly, and of activated human SMO in complex with the essential downstream pathway component GRK2. Our findings will aid future structural studies on SMO by single particle cryogenic electron microscopy (cryo-EM). Ultimately, these cryo-EM structures will provide insights into the evolutionary divergence of SMO activation mechanisms, and into the mechanisms of vertebrate HH signal transduction. Moreover, we conducted functional characterisation of novel HH pathway inhibitors, which were identified in collaborative projects by high-throughput screening and computational docking. These resulted in the identification of six small molecule series that can inhibit HH signalling, three targeting the SMO extracellular cysteine-rich domain (CRD), and three potentially targeting the transmembrane domain (TMD). The ligands targeting the SMO CRD inhibit vismodegib-resistant mouse SMO-D477G, and are currently undergoing medicinal chemistry optimisation to ultimately enable potential therapeutic applications. Furthermore, these compounds can be used in future structural and functional studies to clarify how SMO selects between different downstream HH pathway effectors.

Keywords: cryo-electron microscopy
hedgehog signalling
G protein-coupled receptor
smoothened
drug discovery
structural biology
Advisor: Siebold, C
Jones, EY
Cold and controlled ion-radical reactions, relevant to the interstellar medium and outer atmosphere

This thesis reports the design, construction, and characterisation of a cryogenic linear Paul ion trap chamber. This cryogenic ion trap chamber will be combined with a magnetic guide as a source of radicals, also described in this thesis, for the study of ion–radical reactions under cold and controlled conditions. Ion–radical reactions are important for the chemistry happening in the interstellar medium and in certain regions of Earth’s atmosphere, where both temperature and pressure are low. Despite their importance, there are very few existing methods for studying reactions between ions and radicals at low temperatures.
The new cryogenic linear Paul trap introduced in this thesis is the first such device to incorporate an in-built time-of-flight mass-spectrometer. The design of the apparatus minimizes the temperature at the ion trap region, down to 10K, and ensures that vibrations induced by the cryogenic system do not adversely affect the resolution of the Coulomb crystal images. The constraints of optical access to the trap center for lasers and imaging of Coulomb crystals have been overcome by the implementation of a new optical system based on off-axis parabolic mirrors. We have successfully trapped and imaged Ca+ Coulomb crystals, and work is in preparation to form molecular ions.
Alongside the work on the cryogenic ion trap, the thesis also demonstrates how a magnetic guide can act as a stand-alone source of state and velocity-selected radical species. In this way, a beam of state- and velocity-selected radicals can be filtered from an incoming beam containing a mixture of different species. The magnetic guide therefore provides a source of cold and controlled neutral reactants. Work is underway to combine the two set-ups, facilitating the study of ion–radical reactions.The cryogenic ion trap apparatus presented here is a truly unique apparatus. It will enable us to study reactions involving a range of state selected molecular ions, which, through reactions with velocity- and state-selected radicals from the magnetic guide, can lead to new knowledge on fundamental reaction dynamics and kinetics.

Keywords: ions
gas phase
radicals
ion trap
cold chemistry
Advisor: Heazlewood, B
Mackenzie, S
Branchwise-real trees and bisimulations of potentialist systems

This thesis concerns two topics. The first treats R-trees, which are a certain kind of metric space tree in which every point can be branching. Favre and Jonsson posed the following problem in 2004: can the class of partial orders underlying R-trees be characterised by the fact that every branch is order-isomorphic to a real interval? I first answer this question in the negative, then go on to establish a connection between these trees and traditional set-theoretic trees. This connection is then put to work, answering refinements of Favre and Jonsson's question, yielding several independence results. I next move on to consider the existence of examples of these partial orders without non-trivial automorphisms. I provide constructions of these subject to increasingly strong uniformity conditions. While these constructions all take place in ZFC, they have a strong forcing flavour.
The second topic deals with bisimulations of potentialist systems, which are first-order Kripke models based on embeddings. Given a first-order theory T we can impose a potentialist structure on the class of models of T by taking either all embeddings or all substructure inclusions between models. I show that these two systems are always bisimilar. Next, by connecting with a generalisation of the Ehrenfeucht-Fraïsé game, I show the equivalence of the existence of a bisimulation with elementary equivalence with respect to an infinitary language. Finally, I turn to the question of when a class-sized potentialist system is bisimilar to a set-sized one, providing two different sufficient conditions.

Keywords: modal model theory
tree automorphism
branchwise-real tree
rigid
potentialist system
forcing
road space
separable
independence result
Suslin tree
uniform
countable chain condition
first-order Kripke model
Ehrenfeucht-Fraïssé game
Martin’s Axiom
bisimulation
continuous grading
Advisor: Hamkins, J
Hrushovski, E
Conceptualising national identity in late twelfth-century chansons de geste composed in French

This thesis challenges previous perceptions about national identity by dissolving the usual boundaries in which literary scholars and critics operate. It contends that the emergence and dynamic reconfiguration of national identity permeates a group of concepts which combine and reformulate themselves within intricate systems of lexical patterns entwined in the text, rather than being confined to a single concept.
Such patterns related to the process of national identity are examined across a corpus of chanson de geste poems taken from the Matter of France which date from around the end of the twelfth century. The corpus comprises Aliscans, La Chanson d’Antioche, La Chanson d’Aspremont, La Chanson des Saisnes and Raoul de Cambrai.
From the beginning of vernacular French literature, terms which one would translate as ‘France’, ‘the French’ and ‘French-ness’ predominantly relate to abstract identity concepts rather than purely geographical ones. The term ‘abstract’ designates lexemes with a shifting, fluid quality which ask for active concretization by a given reader or listener, but also cue his or her concretization in a potentially deliberate way. The analysis thus informs a revised notion of national identity as an imagined community emerging over patterns of language use. The chosen methodology and analytical toolkit opens up a new way of exploring these aspects of the texts.
Chapter 1 explores the question of French national identity at a key juncture in the development of ideas of ‘French-ness’. Chapter 2 investigates how France relates to national identity. This examination includes geographical and political aspects which comprise identity, memory, and territory in the reader’s concretizations of individual instances of language use. Chapter 3 considers who and what is ‘French’ in the corpus and the complexity and non-linearity of the French and ‘French-ness’.
The methodology used in this thesis uses a hybrid approach to textual analysis: data is extracted and then subjected to painstaking philological work, complemented by quantitative analysis in an original way. The interpretation of results is informed by insights from existing scholarship and engages in a productive dialogue with this research, which tends to discuss national identity with respect to much later periods. This dissertation indicates that national identities are already being formed in the late twelfth century.

Keywords: linking national identity to language
chansons  de geste
medieval France
community and memory
creating identities
harnessing digital tools in philology
national identity
emotion
Old French epic
rethinking the notion of an imagined community
medieval French
France and French-ness
mobilizing crusade as memory
producing communities
Advisor: Skoda, H
Punishing mobility: membership, race, and privatization in all-foreign prisons in the United States of America

My DPhil thesis examines a set of outsourced, all-foreign prisons operated by the US Federal Bureau of Prisons called Criminal Alien Requirement (CAR) facilities. In operation from 2000 to 2023, these prisons were unique for a series of reasons. First, they were explicitly designed to segregate foreign national offenders from the rest of the Federal prison population. Second, they were the only outsourced prisons within the Federal prison system, and operated under a separate, less-stringent regulatory regime. These all-foreign prisons also disproportionately incarcerated Latino men (89%) in general, and Mexican men (72%) in particular.
This thesis asks what the imbrication of punishment and migration control within all-foreign prisons can tell us about the contemporary nation-state. I develop this argument along three lines. First, I argue that the emergence, operation, and closure of this outsourced all-foreign prison system illustrates the evolving relationship between prisons and migration control. Analysis of the creation of the Criminal Alien Requirement prison system shows us how political leaders imagined a new kind of penal process – what I call the ‘prison-to-deportation pipeline’ – in which deportation became the default result for people without citizenship.
Second, my research demonstrates how outsourced incarceration has become premised on the differential treatment of racialized foreign-national offenders. Criminal Alien Requirement prisons have pioneered a new kind of carceral economy where financial value is extracted from the social and biological reproduction of offenders themselves. I demonstrate how this economic model of incarceration is premised on the differential treatment of non-citizens, and the racialized commodification of illegality.
Finally, my research demonstrates how this system of differential penal treatment produced experiences of abandonment and precarity. These experiences of abandonment defined exclusion from political membership in material and symbolic terms. I argue that paying attention to the ways in which people incarcerated in all-foreign prisons articulated their exclusion offers us a way to begin challenging what Angelica Chazaro calls the ‘criminal alien paradigm’ and uncoupling practices of punishment and migration control.

Keywords: citizenship
deportation
border control
incarceration
race
punishment
privatization
Advisor: Bosworth, M
Investigating nonlinear integrable optics with a Paul trap

Designing high-intensity accelerators has traditionally relied on using computer simulations to study the beam dynamics. As intense beams are comprised of large numbers of particles, all interacting via Coulomb forces, such simulations require significant computational power in order to numerically predict these interactions. The Intense Beams Experiment (IBEX) is a linear Paul trap that can replicate the transverse beam dynamics in accelerators by trapping low-energy ions using RF electric fields that emulate the magnetic focusing elements of particle accelerators. IBEX’s flexibility allows different lattice designs and beam intensities to be tested with ease, which means that it can be used to test novel lattice configurations for high-intensity accelerators. Examples of such lattices arise from the theory of Nonlinear Integrable Optics, and, as discussed in this thesis, the related theory of Quasi-Integrable Optics (QIO). These theories suggest techniques for introducing nonlinear elements such as octupoles into an accelerator lattice, while keeping the system integrable and hence maintaining stable particle motion.
In this work, an upgrade to the original IBEX trap was designed, manufactured, and commissioned with the aim of experimentally testing the principles of QIO. Simulations were used to test the ability of a quasi-integrable lattice to damp a space-charge-driven coherent resonance without exciting the 4th order incoherent resonance in the vicinity. This lattice was then compared to a lattice which broke the integrability conditions, which was shown to excite the 4th order resonance. Using the newly-commissioned IBEX-2 trap, we were then able to test the quasi-integrable lattice experimentally and verify the results from simulations. This thesis demonstrates the first ions successfully trapped in a quasi-integrable lattice in a Paul trap, and discusses the benefits of introducing octupole elements according to the method prescribed by the theory of QIO. The experimental results presented here show the potential value of QIO to research on high-intensity beams in accelerators.

Keywords: high-intensity accelerators
landau damping
quasi-integrable optics
coherent resonances
Paul trap
nonlinear integrable optics
Advisor: Reichold, A
Sheehy, S