VictorJuiz/thesis huggingface dataset:
Development of silver nanocatalyst for propylene selective oxidation reaction
Keywords: Heterogeneous catalyst
Geometric modification
Single atom silver catalyst
Molecular oxygen adsorption
Ethanol production
Selective oxidation
Propylene oxide

Propylene is the second most important starting chemical in the petrochemical industry after ethylene. Unlike ethylene, propylene readily undergoes substitution reactions including polymerisation, oxidation, halogenation, hydrohalogenation, alkylation, hydration, oligomerization and hydroformylation, which lead to a wide variety of important downstream products. One of the principal uses of propylene is to produce key chemicals from selective oxidation. In 2016, the world annual production of propylene is about 94 million tonnes, and the global proportion used to produce selective oxidation product is over 18%. They constitute a key part of the chemical industry and contribute towards substantial economic benefits. The application of Ag based heterogeneous catalysts to selective propylene oxidation is a key factor in the synthesis of nearly all downstream chemicals, however billions of pounds are lost every year due to unplanned reactor shutdown, safety control and environment unfriendly emission control as a results of inefficiency catalytic selectivity and activity. Despite, both theoretical and experimental research works have been intensively involved, the fundamental reason leading to these effects are not yet well understood.
The work presented in this thesis explores a range of novel modification techniques that alter the activity of Ag nanocatalysts for selective propylene oxidation, especially in propylene epoxidation. Particular focus is placed on developing surface modified Ag catalysts through morphology control, surface architecture engineering with another sublayer metal. Using a combination of modelling, novel and traditional materials characterisation methods, it is found that these modification result in some significant electronic and/or geometric alterations to the Ag nanoparticles surface. The Ag-Ag bond distance can be dramatically enlarged by exposing a high-index Ag surface or a core-shell structure with monolayer Ag shell. When interacting with molecular oxygen, the molecular oxygen adsorption and dissociation behaviour is sensitive to the geometric changes in Ag surface. This leads to an enhanced selectivity toward propylene epoxidation than combustion resulting from preventing a C-H bond cleavage.
Finally, be creating atomically dispersed Ag on zeolite, a completely different interaction between molecular oxygen and single atom Ag were discovered comparing to on a extensive silver surface. This leads to the observation of an excitingly new propylene oxidation reaction producing ethanol and CO2 resulting from C=C bond cleavage. Overall, the research presented within this thesis demonstrated a number of methods for the intelligent design of novel heterogeneous Ag catalysts with remarkable activity and selectivity toward specific selective propylene oxidation. These modification methods are believed to be potentially applicable to a wide range of other catalytic reactions.
Small heat shock protein interactions with in vivo partners
Keywords: Heat shock proteins
Molecular chaperones
Cardiovascular disease
Mechanobiology
Native mass spectrometry

Small heat-shock proteins (sHsps) are part of a broad cellular sys- tem that functions to maintain a stable proteome under stress. They also perform a variety of regulatory roles at physiological conditions. Despite the multitude of sHsp targets, their interactions with partners are not well understood due to highly dynamical structures. In this thesis, I apply a variety of biophysical and structural approaches to examine distinct interactions made by the abundant human sHsps αB-crystallin and Hsp27. First, I find that αB-crystallin binds a cardiac-specific domain of the muscle sarcomere protein titin. A cardiomyopathy-causative variant of αB-crystallin is shown to disrupt this interaction, with demonstrated implications for tissue biomechanics. Next, I investigate the conformation and unfolding behaviour of another sarcomere-associated protein, filamin C, finding support for the hypothesis that it is mechanosensitive. This leads into an interrogation of the interaction between filamin C and Hsp27, which we find is modulated by phosphorylation of Hsp27. This modulation only manifests during filamin C unfolding, pointing toward a protective chaperoning mode against over-extension during mechanical stress. This finding is bolstered by up-regulation and interaction of both proteins in a mouse model of heart failure. I establish a system for similar studies of a third sHsp, cvHsp, which is muscle-specific and implicated in various myopathies but scantly understood at the molecular level compared to αB-crystallin and Hsp27. Finally, I probe the stoichiometries and kinetics of complexes formed between αB-crystallin and Hsp27 themselves, which co-assemble into a highly polydisperse ensemble. This involved the development of a high-resolution native mass spectrometry method for disentangling heterogeneous systems. Together these findings add to our understanding of the roles and mechanisms of ATP-independent molecular chaperones.
Absolute quantification of human in vivo hepatic 31P magnetic resonance spectroscopy at 7 tesla
Keywords: phosphorus
liver
magnetic resonance spectroscopy
human
31P
in vivo
absolute quantification

Phosphorus (31P) metabolites are emerging liver disease biomarkers. This work aims to develop a quantification protocol for human hepatic 31P magnetic resonance spectroscopy (MRS) at 7 tesla (T). It should have high SNR, deliver robust measurements of metabolite concentrations with high reproducibility, and be feasible to use in clinical studies. This will allow detailed characterization of liver metabolism in diseases such as cirrhosis, increasing the utility of 31P-MRS as a clinical tool.
A 3D chemical shift imaging method using a 16 channel 31P array at 7 T is chosen to give high SNR 31P spectra from the human liver in vivo, while also providing good spatial localization and spectral resolution.
The Oxford Spectroscopy Analysis (OXSA) toolbox, our MATLAB-based processing software package, is introduced and adaptations for analysis of liver spectra are described.
Five volunteers were scanned to determine T1s for the ten visible 31P metabolites. Simulations were used to determine design criteria for calibration phantoms at 1.5, 3 and 7 T. I compare three candidate approaches to give "absolute" concentrations in mmol/L wet tissue using a 10 cm loop coil, and then extend these approaches to data acquired using the 16 element receive array.
The final protocol was applied to data acquired in ten healthy volunteers and eleven patients with cirrhosis to determine reproducibility and the differences between healthy and diseased livers. This protocol allows distinction between healthy and cirrhotic livers with 90% specificity and sensitivity, using cut-offs in either γ-adenosine triphosphate or inorganic phosphate concentrations.
This 31P-MRS absolute quantification protocol is an important first step in fully utilising the increased SNR afforded by the 7 T scanner, offering valuable insight into liver metabolism, and paving the way for other novel 31P-MRS methods to be developed in the liver at 7 T.
The effect of in vitro culture conditions on cell metabolism
Keywords: Cell culture
Mitochondria
Metabolism
Metabolomics
Glucose
Oxidative stress

Because cells have adapted to respond to their extracellular environment, the in vitro conditions under which cells are cultured have the potential to impact on cell metabolism. This study aims to investigate the effect of various components of culture medium on the metabolism of Chinese Hamster Ovary (CHO) cells.
Firstly, the effect of glucose and glutamine, two important carbon sources, was investigated. The impact of these nutrients on cell growth, viability, oxygen consumption rate (OCR) and steady state ATP levels was assessed. Glucose was found to have a suppressive effect on OCR, while under glucose limiting conditions, glutamine was able to enhance OCR. Although commonly considered a waste product, lactate can also act as a source of carbon and can be consumed by CHO cells. The effect of lactate on the above parameters was also measured, but no robust changes were observed.
Serum is added to the majority of cell culture media and is necessary for cell growth. However, since this product is animal derived, batch to batch variability is high and its composition is not well documented. The broad profile of components in serum means it has the potential to exert many effects on cells, but the effect serum of on cell metabolism is poorly understood. For this reason, the metabolic state of CHO cells in reduced serum was investigated using the aforementioned assays. Metabolite profiling was also performed using metabolomics. Cells cultured in 10% foetal bovine serum (FBS) were found to have a higher OCR than those cultured in both 1% and 0.1% FBS. This was supported by metabolite profiling which showed a greater abundance of tricarboxylic acid (TCA) cycle intermediates in these cells. The metabolite data also indicated increased oxidative stress in cells cultured in 10% FBS. Glucose metabolism also appeared to be affected, with a higher abundance of early glycolytic and glycogenesis intermediates in cells cultured in low (0.1%) serum.
This study shows that both the substrates available in culture media and the commonly used supplement, FBS, can influence metabolic pathways within mammalian cells, meaning their effects must be accounted for, particularly in studies of metabolism.
Genotype-phenotype maps for gene networks: from evolution to computation
Keywords: algorithmic information theory

One of the most fundamental and least understood elements of evolution is the mapping between genotype and phenotype. Recent work on genotype-phenotype (GP) maps suggests that these maps show properties which may have important evolutionary implications. These properties include a skewed distribution of genotypes over phenotypes, linear scaling between phenotype robustness and the logarithm of phenotype frequency, and a positive correlation between phenotype robustness and evolvability. However, most of these properties have only been studied for self-assembling systems, such as protein complexes or RNA folding. In this thesis, we ask ourselves if these properties are more general.
First, we apply tools from algorithmic information theory to a wide class of inputoutput maps, of which GP maps are a subset. We find that these maps show a strong bias towards simple phenotypes, a pattern known as simplicity bias. We also define a matrix map of tunable complexity, with which we can study the conditions under which simplicity bias is present.
Next, we investigate multiple models of GP maps for gene regulatory networks (GRNs). These include Boolean threshold networks, where we fix the strength of gene interactions, while varying the network topology, as well as systems of differential equations, where we fix the network topology while varying interaction strengths. For both modelling frameworks, the GRN GP maps exhibit all the structural properties found in the literature, as well as simplicity bias. We also find that the number of genotypes mapping to the wild-type phenotypes for various GRNs is unusually large, and argue that this is evidence that the structure of the GP map plays an important role in determining evolutionary outcomes.
Finally, we return to more general input-output maps, and show that in addition to simplicity bias these maps also present randomness deficiency, that is, their output spectrum is less complex than expected. We argue that this additional property combines with simplicity bias in GP maps, and more generally, in input-output maps, and suggest a general trend towards simplicity in nature.
The dominant party system in Uganda: Subnational competition and authoritarian survival in the 2016 elections
Keywords: Local politics
Museveni
Uganda
Authoritarian elections
African politics
NRM
elections

This thesis studies the authoritarian dominant party system in Uganda during the 2016 general election. It focuses on how subnational competition within the ruling National Resistance Movement (NRM) prolongs the tenure of its leader, 30-year incumbent President Yoweri Kaguta Museveni. In three districts where the NRM has been historically strong – Kyenjojo, Kayunga, and Bugiri – the thesis traces three processes to this end: the decentralisation and localisation of accountability politics away from the regime and toward expendable local politicians (H1); the relationship between local elite rivalry and the NRM’s collective mobilisation for Museveni’s simultaneous re–election (H2); and how competitive electoral pressures on NRM MPs alter the national elite bargain in the president's favour (H3). It concludes that in strong NRM areas, the fractious divisions that characterise intra-party competition are not a by-product of its near monopolistic domination of politics, but the very basis of that dominance. This emphasis on subnational intra-party competition brings a new variable into a literature on non-democratic survival that tends to focus on more narrowly coercive and clientelist regime strategies.
The thesis presents this argument in a qualitative single case study driven by an open and inductive fieldwork component throughout the 2016 election period. Its three hypotheses are built on data from interviews (with voters and elites), ethnographic observations, official data, and secondary sources. This data is used in a process-tracing design before its conclusions are fortified by a subnational comparative analysis of the election results in the three case districts.
Stochastic analysis and stochastic PDEs on fractals
Keywords: Partial Differential Equations
Calculus
Fractals
Probability
Geometry
Stochastic Analysis

Stochastic analysis on fractals is, as one might expect, a subfield of analysis on fractals. An intuitive starting point is to observe that on many fractals, one can define diffusion processes whose law is in some sense invariant with respect to the symmetries and self-similarities of the fractal. These can be interpreted as fractal-valued counterparts of standard Brownian motion on Rd. One can study these diffusions directly, for example by computing heat kernel and hitting time estimates. On the other hand, by associating the infinitesimal generator of the fractal-valued diffusion with the Laplacian on Rd, it is possible to pose stochastic partial differential equations on the fractal such as the stochastic heat equation and stochastic wave equation. In this thesis we investigate a variety of questions concerning the properties of diffusions on fractals and the parabolic and hyperbolic SPDEs associated with them. Key results include an extension of Kolmogorov's continuity theorem to stochastic processes indexed by fractals, and existence and uniqueness of solutions to parabolic SPDEs on fractals with Lipschitz data.
Proﬁnite properties of 3-manifold groups
Keywords: Profinite groups
3-Manifolds

In this thesis we study the finite quotients of 3-manifold groups, concerning both residual properties of the groups and the properties of the 3-manifolds that can be detected using finite quotients of the fundamental group.
A key theme is the analysis of when two 3-manifold groups can have the same families of finite quotients. We make a detailed study of this 'profinite rigidity' problem for Seifert fibre spaces and prove complete classification results for these manifolds.
From Seifert fibre spaces we continue on this trajectory and extend our classification results to all graph manifolds. We illustrate this classification with examples and several consequences, including for graph knots and for mapping class groups.
The third part of the thesis concerns the behaviour of the finite p-group quotients of 3-manifold groups. In general these quotients may be scarce and poorly behaved. We give results showing that some of these issues may be resolved by passing to finite-sheeted covers of the manifold involved. We also prove theorems concerning the p-conjugacy separability of certain graph manifold groups.
The concluding chapter of the thesis collects other results linking low-dimensional topology and finite quotients of groups. In particular we prove that finite quotients of a right-angled Artin group distinguish it from other right-angled Artin groups, and we give an argument detecting the prime decomposition of certain 3-manifold groups from the finite p-group quotients.
The grounds of unity: substantial and sub-substantial being in Aristotle
Keywords: Aristotle
metaphysics
matter
form
hylomorphism

Strawson famously classified Aristotle as a descriptive metaphysician, alongside himself, and in contrast to more revisionary philosophers like Plato. The extent to which Aristotle was merely concerned to describe our conceptual scheme has, however, been over-estimated by some. Although common-sense beliefs are among the starting-points from which Aristotle pursues his metaphysical inquiries, the conclusions of those inquiries are in fact quite radical.
In chapter one, we identify three interpretative questions about Aristotle’s notion of substance:
(1) does Aristotle change his mind about what things are the substances between writing the Categories and the Metaphysics?
(2) are matter, form and the compound of the two all substances, albeit to different extents, or are only forms substances?
(3) however we resolve these questions about hylomorphism, what range of forms count as substantial, and why?
In chapter two, we examine the criteria of being a substance. These provide evidence for Aristotle’s changing his mind between the Categories and Metaphysics. An examination of the ‘χωριστόν’ criterion also supports the view that only forms are substances: Aristotle claims that compounds are separate simpliciter, since they can exist without items in other categories, and not vice versa, but this claim cannot be supported. Only forms are separate in definition, and so, on the assumption that being separate is necessary for being a substance, only forms are substances.
If we are to understand the claim that only forms are substances, we should acquire a better understanding of what is meant by ‘form’, and why Aristotle thinks there are such things. Chapters three to five undertake this task. Chapter three discusses Aristotle’s introduction of matter and form in the Physics to account for substantial generation, and his argument in Z.17 that form is substance, since it is what makes some matter one thing. In chapter four, this unificatory role is distinguished from the role of a principle of individuation, and it is argued that only individual forms are suitable to play the latter role. In chapter five, we examine some recent attempts to blur the distinction between matter and form, by maintaining that form is essentially matter-involving. We argue that the view according to which form is defined independently of matter is preferable.
In chapters six and seven, we address the third interpretative question. Chapter six argues that artefacts are not substances (and not merely substances to a lesser degree than organisms) because they are not separate, since they depend on the intentional activity of their creators or users. Chapter seven considers Aristotle’s views about mixtures. These are also compounds of matter and form, but fail to be substances because, like matter, they depend on a higher form to make them one thing.
When value chains go south: governance and upgrading of the Kenyan leather sector
Keywords: Entrepreneurship
Global Value Chains
Upgrading
Governance
South-South trade
Africa
Kenya

In the last three decades, the global economy has witnessed an ambivalent phenomenon of integration through disintegration. Whilst the amount of regional and global trade dramatically increased, vertical specialisation prompted the outsourcing of manufacturing, assembling, and other business functions regionally and globally. The slicing up of value chains and the consequent surge in trade of intermediate goods drew the attention of scholars interested in the economic, social, and environmental consequences of this phenomenon. Yet, most of the literature on value chains has concentrated on the institutional and market linkages between firms in developed economies and delocalised suppliers in the global South. Conversely, less attention has been paid to the rise in South-South trade that accompanied the development of South- South and regional value chains.
The following chapters provide new evidence on the opportunities and constraints that participation in value chains across North-South, South-South, and regional trajectories entails for local suppliers in developing countries. This is achieved by means of a mixed-methods approach that combines firm-level export data with over 100 semi-structured interviews across the Kenyan leather sector.
On the one hand, results show how North-South value chains are characterised by more profitable and stable relationships between buyers and local suppliers. Nonetheless, whilst defined by higher product and process standards, linkages with developed economies appear to prevent rather than encourage local value addition. On the other hand, South-South value chains are governed by instability and distrust underpinned by pressures to reduce prices and lack of upgrading opportunities.
Like the global South, regional value chains are characterised by fierce competition and low profitability. Even so, they often constitute an alternative for small suppliers willing to venture into new products and functions. Particularly, the local and regional markets represent an upgrading platform for innovative firms whose low capital endowments prevent them from accessing premium North-South value chains. In this case, industrial policy and entrepreneurship play a crucial role in enabling smallholders to upgrade in a competitive environment.