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Connecting mantle flow below passive margins and intraplate melt generation: an application to the Cameroon Volcanic Line.
Get PDFMantle plumes are the prevailing explanation for intraplate volcanism, with an age progression along the plume track and a geochemical signature suggesting a core-mantle boundary origin. But these observations do not correlate with some intraplate volcanism examples, requiring alternative
mechanisms to explain these outliers.
One potential example is the Cameroon Volcanic Line (CVL), a large-scale near-linear chain, lacking an age progression with a suspected asthenospheric origin. Edge-driven convection (EDC) is a proposed mechanism and is a process which forms in regions of lithospheric thickness gradients,
such as craton-oceanic boundaries. A self-sustained convection roll may form, bringing material from depth to decompress and melt. However, previous EDC work provides disagreeing results, and shows that melt generation in this process is a complex process. This thesis aims to test a recent hypothesis that an additional ‘fertile layer’, derived from metasomatized material at the base of a craton which has undergone continental collision, could aid in magma genesis and explain why EDC-derived melt is not widespread.
The use of 2D numerical models allows for a parameter sensitivity study on rheological parameters, with an ocean spreading model used to test additional parameters and examine the dynamics of this hypothesized fertile layer, which is used as a proxy for melt generation. Results show that oceanic spreading velocity is the most influential parameter in moving fertile material into the continent-ocean transition (COT), as shear-driven upwelling forms at higher velocities.
When applying the results to the CVL, fertile material moves into the COT, while EDC occurs as well. However, due to the slow spreading rate of the Atlantic, processes such as shear-driven upwelling is not influential. As such, it is proposed that further additional factors must influence
the magmatism, and that modelling of the 3D geological complexities of the CVL is required to gain further insight
Growth of Graphene and MoS2 by Chemical Vapour Deposition
Get PDFThe growth of two-dimensional materials by low-cost atmospheric pressure chemical vapour
deposition (AP-CVD) is explored in this thesis, with an emphasis on understanding key
features of the growth process. In particular, the growth of graphene on copper foils using
a methane precursor, MoS2 on natively oxidised silicon and MoS2 on graphene, graphite
and graphene ‘paper’ were studied. The resulting few-layer, monolayer and sub-monolayer
films were characterised by a combination of Raman spectroscopy (RS), Scanning Electron
Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).
Through varying the methane flow rate, it was found that there is no self-limitation to
graphene growth at high methane concentrations, resulting in graphene multilayers that can
delaminate from the copper substrate. The effect of a number of surface pre-treatments on
graphene growth is also presented. Nitric acid etching of copper foil was found to produce a
superior growth surface in comparison with those prepared with acetic acid or electropolishing, evidenced by a reduction in nucleation density and increased island size. Raman spectra
showed a remarkable correlation with these observations, indicating increased hole doping
with improved sample treatment. Therefore, Raman spectroscopy may be used as a probe
for the effectiveness of surface preparation. Several different approaches to the growth of
MoS2 on natively oxidised silicon by AP-CVD using S and MoO3 precursors are presented.
It was found that the growth of MoS2 was strongly dependent on the timing with which a
sufficient sulphur flux is introduced into the growth region. These results led to an investigation into the influence of sulphur partial vapour pressure on MoS2 growth. It was found
that MoS2 coverage decreased with increasing sulphur vapour pressure. These results could
be successfully rationalised by the Langmuir-Hinshelwood model of growth kinetics, which
is usually applied to reactions on well-defined crystalline surfaces and had not previously
been considered for MoS2 growth. XPS was used to study the composition of AP-CVD
grown MoS2 as a function of sulphur evaporation temperature and provided clear evidence
that lower sulphur vapour pressure leads to an increased concentration of sulphur vacancy
defects.
Attempts were made to grow MoS2 directly on highly oriented pyrolytic graphite as a
model substrate. MoS2 was found to grow on graphite under similar conditions to those
for natively oxidised silicon, but nucleation was observed to occur primarily at a defect (step)
sites. Attempts to grow MoS2 directly on graphene CVD grown on copper, commercially
sourced graphene powder, and graphene paper are also reported
Advances in the understanding of Kohn-Sham DFT via the optimised effective potential method
Get PDFKohn-Sham (KS) density functional theory (DFT) has paved its way to becoming the most widely used method for performing electronic structure calculations. Its major success relies heavily on the underlying approximations that are employed to describe the exchange-correlation (xc) energy functional; hence understanding these approximations proves to be of vital importance.
The main goal of this thesis is to explore and develop a deeper understanding of approximations made within DFT; with a focus on systematically improving existing (semi-)local density functional approximations (DFAs). To do so, we build upon the existing constrained minimisation method, which requires the optimised effective potential (OEP) scheme, improving its implementation and removing one of its major computational bottlenecks.
This thesis also addresses a long-standing question in the field as to why the KS equations of spin-DFT do not reduce to those of DFT in the limit of zero applied magnetic field. A new OEP scheme is derived to construct DFT approximations that yield near spin-DFT accuracy and correct for a systematic error in the exchange energy for open-shell systems. This work is then extended to ensemble systems of varying electron number, where it is shown that (semi-)local approximations can yield non-zero xc derivative discontinuities; an exotic, non-analytic feature of the exact KS potential.
Building on these new OEP formulations, a novel new method for decomposing the molecular screening density into screening densities localised on individual atoms is introduced. This method is shown to yield the predicted but elusive steps in the xc potential as a diatomic dissociates; a very exciting result given that these steps cannot be captured at all from any DFT so far, let alone a (semi-)local DFA
Engaging Children in Question Asking for Problem Finding to Encourage Creative Thinking in Primary School Science Teaching
Get PDFEncouraging creative thinking is considered as the general function of education (NACCCE, 1999) and one of the aims under the national curriculum of England (DfEE/QCA, 1999). Though creative thinking is a broad term, in science it is seen as finding solutions to problems(D. P. Newton, 2010).Scientific enquiry is a creative process, commonly beginning with a question or problem, then generating a tentative answer or solution, and testing it. Generally teachers provide ready-made questions or problems for children to solve. If children themselves can find scientific problems or questions to solve in the classroom, then learning would be more engaging as it generates interest and motivation.
A review of existing literature on creativity in education focusing on its least recognised aspect, problem finding, revealed the potential for children's questions, particularly wonderment questions in encouraging deep thinking. Some studies recognised the scarcity of children's questions especially explanatory questions and questions that leads to investigations in the primary school science classroom. Therefore, the study sets out to explore strategies to stimulate children to raise questions with the potential to become problems to solve in science.
The study employed mixed methods using a descriptive questionnaire survey, classroom observations, short interviews, content analysis and controlled interventions with children to collect data. The sample included teachers, student teachers and Key Stage Two primary school children. It used phenomenography to analyse the data and derive useful conclusions thereby following an interpretivist approach.
A theory explaining the complex process of question asking which involves the construction and articulation of descriptive and causal mental models of situations emerged from the study. Several factors are suggested which influence and order the process, especially the situation or stimulus, the teaching and learning environment, and the attributes of the child. It takes time to produce questions which could lead to scientific enquiry and it needs teaching skill to provide effective opportunities for children to ask questions, and help them put them into a suitable form
Can culture shape moral identity? A comparative study of children’s moral identity in China and England
Get PDFThis PhD thesis presents a general picture of young adolescents’ moral views and behaviour in two countries. The study also examines the assumption that culture plays a role in forming young people’s moral views and moral behaviour and the implications for moral education and moral evaluation.
The study is a large-scale cross-sectional comparison between primary school children in China and England. The sample consists of 1,950 primary school students between 8 and 13 years old (average age=10.2, standard deviation=0.9). The 1,768 Chinese participants are from eight public schools in the capital city (Beijing) and three smaller cities in China. 107 British participants are from two similar state-funded schools in northeast England (Durham and Newcastle), and 75 were recruited online from various cities across England (e.g. London, Newcastle, Durham and Edinburgh). The British sample is smaller than expected because of COVID-19.
All the participants took part in a questionnaire survey. A subset of 278 randomly selected participants joined in a game observation operationalising some of the moral issues in the survey.
The questionnaire survey mainly concerned children’s self-reported moral identity (the self-reported importance of the moral values of fairness, kindness/not hurting and honesty) and their intended behaviour in response to these moral values. The second research tool in the study was a game-based activity to observe actual behaviour. A sub-group of the survey sample participated in the game and they were requested to act independently on charity donation and distribution tasks. Their survey responses on their moral identity, intentions and motivations were then compared with their actual behavioural responses in the game. Consistency between students’ behavioural intentions in the survey and their actual behaviour in the game was evaluated.
The main findings of the study are the following:
(1) There is a gap between young adolescents’ moral values, value commitments (intentions)
and actual moral behaviour.
(2) Young adolescents have a similar self-reported importance of moral identity and moral
trait understanding to adults.
(3) Young adolescents from both countries reported a relatively solid moral identity and
showed similar behaviour patterns (to be generous or fair in different situations). They also considerably overlap in their understanding of important moral traits. However, the Chinese adolescents generally achieved a higher mean score for reported moral identity and demonstrated stronger consistency of behaviour than the British adolescents.
(4) There were some indications that cultural similarities and differences exist between China
and England from the young adolescents’ perspectives. The cultural difference in individualism between China and England is not as big as the difference in collectivism.
(5) It was found that personal values and nationality predict moral identity and behaviour to
different degrees. Moral identity and behaviour intention are predicted by both personal values and nationality. Actual moral behaviour is only predicted by nationality. Consistency of moral behaviour is only predicted by personal values. Norm priming (e.g. being told what most peers do) is related to actual moral behaviour but not to consistency of behaviour.
(6) Student socioeconomic background is related to moral identity and moral behaviour.
(7) The study not only linked moral identity to actual moral behaviour but also to consistency
of behaviour. It revealed that cultural and socioeconomic differences should be considered when exploring whether moral identity predicts moral behaviour. This is ignored in some existing research in this field, producing potentially misleading results.
(8) Generally, the study implied that moral education and moral evaluation need to be more practical and fairer, and consider moral dilemmas (value clashes) in real life, potential social desirability, how understanding and expression can bias measuring tools, unobservable motivations behind behaviour and students’ different socioeconomic backgrounds. The gap between moral thoughts (intentions) and actual behaviour implies that future studies and moral evaluations should rely less on self-reporting/introspection and focus more on moral behaviour itself. The fact that the combination of individual-level cultural values and nationality predicts students’ moral identities and behaviour intentions implies that educators should pay attention to the influence of national cultural values on students’ morality when focusing on cultivating their personal moral values. Learning from the moral education model in a different culture requires considering the influence of local culture on the model’s outcome. Norm priming (e.g. being told most peers’ generous behaviour) can help with motivating students’ moral behaviour. Moral identity can help shape students’ moral behaviour. However, many other factors should be considered when attempting to shape students’ moral behaviour by strengthening their moral identity. Value commitment through actual behaviour in real life need to be strengthened to reach a mature morally-based identity for adolescents
Developing International Mindedness through the Arts in the International Baccalaureate (IB) Diploma Programme (DP): An International Survey Design Conducted across all Continents
Get PDFOne distinct purpose of international education is to develop greater international understanding and intercultural competences. For the International Baccalaureate, this translates into students developing international mindedness throughout its programmes and courses. However, international mindedness is not measured and the impact of the programmes on the development of international mindedness remains mainly anecdotal. Furthermore, in the Diploma Programme, the choice of Arts courses is optional and the value of an Arts education, or specifically the value of taking a Diploma Programme Arts course in developing international mindedness, is equally unclear. This study investigated the development of international mindedness in students who opted for a Diploma Programme Arts course versus those who did not. The study followed a repeated measures, comparative and mixed-methods research design using a survey tool for data collection. The survey consisted of a quantitative section based on existing surveys and a qualitative section with six open-ended questions. The quantitative data showed an increase in intercultural knowledge and behaviours, while no change in attitudes, and a decrease in values was identified for both student groups, Diploma Programme Arts and Non-Arts-students. Furthermore, there was an increase in intercultural communication skills particularly in Diploma Programme Arts-students. Qualitative data analysis revealed a spectrum of categories of responses. The qualitative data also identified themes in addition to those identified in International Baccalaureate documentation and literature. Recommendations include for the International Baccalaureate Organization to integrate some of the emerging themes in their documentations, for example themes relating to adaptability and interconnectedness, which may also provide an interesting focus for curriculum design. Furthermore, curriculum and programme design should place a greater focus on the development of attitudes and values in the Diploma Programme and a reconsideration of the optionality of the Arts in this context
Controlling the Environmental Impacts of UK Fast Fashion Companies: Do B Corps provide a way forward?
Get PDFThis thesis is looking at the problem of the environmental harm caused by the fast fashion sector, and how the law might seek to regulate this harm. It focuses specifically on regulation that targets companies involved in the production and sale of fast fashion, so in this sense, it looks at how ‘corporate law’ might address the environmental harm. However, it does not look at all that corporate law might have to say. Instead, its focus is again narrower. It's asking, specifically, how far corporate law can go by merely enforcing the commitments which companies themselves make to acting in an environmentally responsible way. Many companies often - for a variety of reasons - choose to make commitments to behave well. In this sense, some companies 'self-select' to be more environmentally responsible. This thesis focuses on how effectively corporate law can enforce these self-imposed commitments.
The main area in which it analyses the law's ability to enforce these self-imposed constraints is through its analysis of so-called 'B Corps' – a private label certifying a company’s commitment to ESG – an institutionalised form of self-imposed constraints
The Ascetic Imagination and the Reception of Early Christian Texts
No full textThe interplay between reception and the creation of ascetic meaning in early Christian writings has been the subject of a diverse range of studies. Much of the focus in this regard, has however, been limited to studying commentary on or citation of biblical texts in ‘exemplary readings’ (the Patristic Fathers) preventing us from accessing the full gamut of the rich history of ascetic interpretation. This thesis demonstrates the utility of looking beyond these limitations by intentionally engaging with texts that are outside of normative Christian tradition and by looking beyond direct citation or explicit commentary to access the diverse modes of reception and meanings inspired by the Christian ascetic imagination.
Accordingly, in chapter one, I looked at the Acts of Paul and Thecla, noting the appropriation and development of Pauline traditions and the utility of the peculiarly vulnerable body of the female virgin Thecla as the locus for ascetic conversion and transformation. In chapter 2, I identified the creative reception of literary forms and motifs to develop an ascetic discourse intended to enable the elect to overcome embodiment, in the Book of Thomas the Contender. In chapter 3, I turn to the classical text of Christian monasticism, the Life of Antony, to establish developments in interpretive practices in a context where the Christian scriptures, ecclesiastical structures, and ascetic praxis were being formalised.
In the second part of my thesis, I went on to compare and contrast these traditions with a focus on the reception of figures, selected discourse, and the processes of ascetic formation to highlight the productivity of mapping the diachronic development of meanings without privileging some readings or seeking to establish genealogical relationships between successive readings
Dionysus against the Crucified: Nietzsche, Sovereignty, and the Power of Nihilism
Get PDFIs international law nihilistic? Being produced from nihilism and driven by it? And are even we nihilistic – we Critical scholars who stand beyond the end of history? Not a break from the past but a continuation?
That is the gambit of this thesis: to explore the nihilistic inner life of international law, through the root and stem of its creation and development, right up until the contemporary movement towards Critical approaches to the discipline. Through the embracing scope of nihilism, I argue that each of these turns and evolutions can be tracked back to a single logic.
The first Volume of this thesis is dedicated to the theorisation of nihilism and how it could be existentially connected to international law. Using the philosophy of Friedrich Nietzsche, I link nihilism to what I term the ‘civilising psychosis’: a process (or sickness) by which the production of the human and the state is co-constitutive. Through this bond, it becomes possible to argue that the structures of nihilism, and the civilising psychosis, frame and condition the development of legal concepts.
In Volume II, I take the civilising psychosis and apply it to the creation of the European global order of sovereign states. Here I suggest that transformations within sovereignty doctrine have been devices of managing and rearticulating the civilising psychosis. Applying literary techniques, this Volume takes the form of a ‘A play in three acts’. Within it, I follow the civilising psychosis, first, in the domestic generation of sovereignty, through to the use of sovereignty in 19th century imperialism, before bringing the civilising excesses of this latter period into confrontation with Critical scholarship. Through the violence of this encounter, I intend to begat recognition and disorientation. Rather than marking a departure from the civilising psychosis, such scholarships could be its most visceral manifestation
Study of Kesterite Cu2ZnSnS4 Thin Films prepared from Cu2ZnSnS4 Nanoparticle Inks
Get PDFDue to the recent rapid industrial and population growth, there has been an
increase in the demand for energy which has led to a strong reliance on non-renewable energy sources which has negative environmental effects. Due to
its unlimited sources and absence of environmentally harmful green house gas
emissions, solar energy has emerged as an effective candidate for renewable
energy. Cu2ZnSnS4 (CZTS) has been widely investigated as an absorber for
thin film solar cells. It can replace Cu(In, Ga)Se2 (CIGS), and CdTe since
it consists of non-toxic, abundant, and cheap elements. Its high absorption
coefficient, optimal band gap, and naturally abundant non-toxic elemental
constituents give it several advantages over most thin film absorber materials. However, the present performance of CZTS solar cells is still below their
theoretical limit. Recently, there has been a rise in interest in improving the
performance and lowering the production cost of solar cells based on CZTS.
In this study, CZTS nanocrystals were synthesized by one of the non-vacuum
techniques: the CZTS absorber is synthesized by using the hot injection technique, and it is responsible for synthesizing the crystalline layer that performs
as the solar cell device absorber. CZTS nanoparticles were synthesized using
a chemical synthesis process, with sulphur being injected into a solution of hot
metallic precursor ions. It was revealed that the reaction temperature and time
greatly influenced their composition, structure, and optical properties. In this
research, a method was proposed to fabricate nonstoichiometric CZTS thin
films. Using soda lime glass and molybdenum substrates, the CZTS thin films
were deposited on the different substrates by drop casting and spin coating
methods, followed by preheating in air and post-deposition annealing treatments, in two different atmospheres, H2S and N2. The CZTS thin films were
annealed at different annealing temperatures. The morphology, composition, structure, and optical properties of the CZTS thin films were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray
diffraction, Raman spectroscopy, and UV-vis spectroscopy. The influence of
the annealing on the morphology, composition, and structure of the films has
been studied. From the XRD patterns of the CZTS thin films, the peaks of all
CZTS thin films are indexed to tetragonal CZTS (PDF 026-0575) and can be
attributed to the (112), (220), and (312) planes of kesterite CZTS, respectively.
The Raman spectra of the samples give evidence that in all spectra the dominant peaks are located at 330–338 cm−1
, indicating that these samples contain
peaks associated with the Cu2ZnSnS4 phase. A significant influence on the
energy bandgap of CZTS thin films was observed during the annealing of thin
films. In addition, the fabrication of CZTS/CdS heterojunctions was explored
to gain a better understanding of the properties of the interface reactions that
take place between the Mo/CZTS and CZTS/CdS layers. the effect of high
annealing temperature on a Mo/CZTS/CdS heterojunction was carried out at
temperatures ranging from 450°C to 550°C at an annealing time of one hour
in H2S and N2 atmosphere . Annealing promotes cadmium diffusion from the
n-type semiconductor to the absorber. According to various studies, Cd diffusion improved the performance of thin-film solar cells. However, at annealing
temperatures of 500 and 550 °C, the presence of a Cu-related secondary phase
was observed, which is detrimental because it introduces shunting routes that
lower the devices’ FF due to its metallic nature and low resistivity profile. In
addition, Mo combines with S at the CZTS/Mo interface to form MoS2, which
leads to losses of Voc, Jsc, and FF in CZTS devices. The findings presented
here indicate that there is significant interdiffusion of the elements from the
different layers in a Mo/CZTS/CdS heterojunction, which occurs at the temperatures commonly used to fabricate CZTS devices. Further improvements
in CZTS devices will require strategies to control this interdiffusion
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