Advanced functional coatings for biomedical applications: patterning cells onto biomaterials

The aim of this work was to develop engineered coatings for protein and cell patterning on a surface. Cell patterning is important for biomedical applications such as single-cell studies, cell microcolonies arrays for high throughput drug screening, and the growth of geometrically controlled cell co-cultures for tissue engineering. In this work, the patterning of cells relied on the controlled positioning of protein domains on a surface, on which the cells could adhere. This was done by dewetting a protein-repellent polymer film from a protein-adsorptive one. Dewetting is the process by which an unstable thin liquid film (such as a polymer over its glass transition temperature) spontaneously breaks up, resulting in the formation of holes. The duration of dewetting controls the dimensions of the holes, from tens of nanometers to tens of microns. By tuning the thickness of the films and the molecular weight of the polymers it is possible to vary the type of pattern that is obtained. The result of the dewetting was a chemically and topographically patterned coating. Proteins in contact with such surface could only adsorb inside the dewetted holes, where the adsorptive polymer was exposed. The first system investigated was dewetted poly(N-vinylpyrrolidone) (PNVP) on polystyrene (PS). PNVP was found to cross-link upon annealing, as well as dewetting from PS. Insoluble cross-linked PNVP films were characterized by neutron reflectometry, infrared spectroscopy and ellipsometry, and found to be stable in water for many days, resistant to harsh solvents, and excellent in repelling proteins. The hole growth observed during concurrent dewetting and cross-linking was fully characterized by time elapsed optical microscopy, and a model was developed to predict it. The pattern obtained by dewetting PNVP could be controlled by selecting the appropriate annealing temperature, in order to tune the ratio between the rates of dewetting and cross-li nking. The PNVP/PS architecture was improved by substit! uting th e PNVP film with a functional polymer brush, in order to achieve a more versatile system. A polymer was designed so as to be able to dewet from PS, as well as bear initiators for the grafting of a polymer brush. This macroinitiator was synthesised by reversible addition-fragmentation chain transfer polymerization (RAFT). A protein-repellent poly(poly(ethylene glycol)methyl ether methacrylate) (poly(PEGMA)) brush was grafted from the dewettable macroinitiator film using activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). This type of polymerization allows growing brushes of controlled thickness, with “living” ends that may easily be post-functionalised with simple chemical reactions, to interact selectively with different biological molecules or cells. The grafting process was investigated by ellipsometry, size exclusion chromatography and X-ray photoelectron spectroscopy. The functional patterned coatings developed were able to effe ctively immobilise extracellular matrix proteins and cells in selected areas of the surface, as shown by fluorescence microscopy and atomic force microscopy. The cells could spread on the surface, showing good viability. The patterned coatings here described could be prepared on non-flat and large objects, offering a simple and cheap alternative to other patterning techniques, such as photolithography and micro-contact printing, and opening exciting prospects in biomedical applications

An exploration of constructions of racial and national identities in US and EU climate security discourses

Grounded in a methodology of critical discourse analysis and semi-structured interviews, this thesis investigates constructions of racial and national identities in US and EU climate security discourses. Utilizing a theoretical framework based on ‘essentializing logics’ (a concept developed to analyze how naturalized assumptions and associations about populations are held in relation to possible climate-insecure futures), the thesis argues that intersectional racial and national identities are constructed in context-specific moments of US and EU climate security discourses and are underpinned by multiple biopolitics of unequally valued lives. This argument is elaborated in three empirical chapters. First, the thesis examines the racialization of ‘Muslim’ and ‘African’ climate-induced migrant populations in particular, situated moments of climate security discourse. The second empirical chapter focuses on discursive representations of interconnections between climate change and terrorism and how such interconnections represent important points of intersection for racial and national identities in climate security. The final empirical chapter examines representations of American nationhood in US climate security discourse. These include constructions of American exceptionalism, the impacts of Hurricane Katrina and Hurricane Sandy for conceptions of American national identity, and the development of ‘climate-resilient’ American nationhood. The thesis concludes by reflecting on the project’s findings. I argue that multi-scalar interpretations of environmental justice (grounded in a manifesto for ‘abundant futures’ (Collard et al (2015)) and Koopman’s (2011) feminist ‘alter-geopolitics’) could provide a tentative means through which to think about more just, situated environmental securities

Phenomenological study of the relationship between a 10-day residential outdoor education experience and patterns of physical activity in adult life

This dissertation investigates the meanings and values that a group of adults aged between 30 and 31 years attribute to a 10-day residential outdoor education experience that took place 17 years ago. The dissertation specifically investigates whether the participants consider that the experience has had any influence on their current patterns of physical activity. Research shows that levels of sedentarism and inactivity amongst the population of the United Kingdom are rising. This is causing concern in Government regarding the impact of this lack of physical activity on the health of individuals, the cost to the National Health Service, and the maintaining of a healthy working population. A review of the literature relating to the role of outdoor education as a means of encouraging physical activity reveals a strong historical connection between outdoor education and physical health in the UK. However, the literature is primarily rhetorical and theoretical in nature and illustrates an absence of complementary empirical work. A phenomenological methodology informed both data collection and analysis. Data were gathered using semi-structured interviews. The results demonstrate that the residential outdoor experience was a very positive experience for the interviewees. The experience was most significant in terms of personal and social development. In terms of the impact of the experience on physical activity patterns in adult life the results demonstrate a relationship which is limited but worthy of further investigation

Meanings, values, and life course: a study of participants’ experiences at a Scottish outdoor education centre

Residential outdoor education has had a significant formal and informal presence within the education system of the United Kingdom since the 1950s. However, there is little empirical research into the experiences of participants, particularly from a long-term perspective. The present study investigates the meanings, values, and impacts that participants attribute to a five-day residential experience at Ardentinny Outdoor Education Centre, near Dunoon, Scotland. Participants attended the Centre as school pupils between 13 and 16 years of age. Ardentinny Outdoor Education Centre operated as an educational facility under the auspices of the local authority between 1973 and 1996. Participants were contacted between 2007 and 2008, hence a minimum of 11 years after the Centre closed. Semi-structured questionnaires (n = 110) and interviews (n = 14) were used to generate data regarding participants’ experiences. These were analysed using a hermeneutic approach. Supplementary data were generated from archival documents and interviews (n = 29) with various stakeholders in Ardentinny Outdoor Education Centre, ranging from local authority education officers to Centre managers and instructional staff. These supplementary data contribute towards a nuanced interpretive account of participants’ experiences that has both breadth and depth. The data suggest that participants’ experiences at Ardentinny Outdoor Education Centre represented highly significant events in their school career. Principal findings relate to themes of achievement, independence and responsibility, and the development of more adult relationships. Seventy-two percent of questionnaire respondents claimed that their experience at Ardentinny Outdoor Education Centre continued to influence their adult lives. This influence was manifested in a variety of ways ranging from a love of the outdoor environment, to choices regarding use of leisure time, to employment choices. Bourdieu’s (1977, 1990b) theory of social practice, particularly the concepts of field and habitus, provides a framework to interpret participants’ expressions of the nature of their experiences and the impact those experiences did or did not have on their lives. From this perspective Ardentinny Outdoor Education Centre presented participants with a safe and authentic experience that differed sufficiently from their previous life experiences to allow for the opportunity to develop new understandings of self and the social world. These new understandings were expressed in different ways and at different times over participants’ subsequent life course

Layered Antiferromagnetism Induces Large Negative Magnetoresistance in the van der Waals Semiconductor CrSBr

The recent discovery of magnetism within the family of exfoliatable van der Waals (vdW) compounds has attracted considerable interest in these materials for both fundamental research and technological applications. However current vdW magnets are limited by their extreme sensitivity to air, low ordering temperatures, and poor charge transport properties. Here we report the magnetic and electronic properties of CrSBr, an air-stable vdW antiferromagnetic semiconductor that readily cleaves perpendicular to the stacking axis. Below its N\'{e}el temperature, $T_N = 132 \pm 1$ K, CrSBr adopts an A-type antiferromagnetic structure with each individual layer ferromagnetically ordered internally and the layers coupled antiferromagnetically along the stacking direction. Scanning tunneling spectroscopy and photoluminescence (PL) reveal that the electronic gap is $\Delta_E = 1.5 \pm 0.2$ eV with a corresponding PL peak centered at $1.25 \pm 0.07$ eV. Using magnetotransport measurements, we demonstrate strong coupling between magnetic order and transport properties in CrSBr, leading to a large negative magnetoresistance response that is unique amongst vdW materials. These findings establish CrSBr as a promising material platform for increasing the applicability of vdW magnets to the field of spin-based electronics

Hypersensitivity to Ticks and Lyme Disease Risk

Persons who report frequent tick-associated itch are less likely to contract Lyme disease than those who do not

High‐performance liquid chromatography (HPLC) as a means of assessing the presence of uric acid in archeological human remains:Challenges and future directions

Objectives: This research aimed to replicate the Swinson, D., Snaith, J., Buckberry, J., & Brickley, M. (2010). High performance liquid chromatography (HPLC) in the investigation of gout in paleopathology. International Journal of Osteoarchaeology, 20, 135–143. https://doi.org/10.1002/oa.1009 method for detecting uric acid in archeological human remains to investigate gout in past populations and to improve the original High Performance Liquid Chromatography‐ultraviolet (HPLC‐UV) method by using HPLC‐mass spectrometry (HPLC‐MS), a more sensitive, compound‐specific detection method. Materials and Methods: We used reference samples of uric acid to create a dilution series to assess the limits of quantification and detection. Samples from individuals with and without gout lesions were taken from foot bones and ribs from the English cemeteries of Tanyard, Hickleton, Gloucester, and Lincoln. Results: We could not replicate the results of Swinson and colleagues using HPLC‐UV. Tests using a dilution series of uric acid showed HPLC‐MS was approximately 100× more sensitive than HPLC‐UV, with the additional benefit of being compound specific. A newly developed hydrophilic interaction chromatography (HILIC) method improved retention characteristics. Fourteen samples from eight individuals, five with skeletal lesions consistent with gout, were analyzed with the final method. None showed evidence of uric acid despite the newly developed method's improved sensitivity and specificity. Discussion: The lack of detectable uric acid extracted from these samples suggests that (1) urate crystals were not present in any of the bone samples, regardless of gout status; (2) urate crystals did not survive these specific archeological conditions; or (3) the concentration of uric acid in our bone extracts was low, and thus larger samples would be required

Spatially-Resolved Recent Star Formation History in NGC 6946

The nearby face-on star forming spiral galaxy NGC 6946 is known as the Fireworks Galaxy due to its hosting an unusually large number of supernova. We analyze its resolved near-ultraviolet (NUV) stellar photometry measured from images taken with the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3) with F275W and F336W filters. We model the color-magnitude diagrams (CMD) of the UV photometry to derive the spatially-resolved star formation history (SFH) of NGC 6946 over the last 25 Myr. From this analysis, we produce maps of the spatial distribution of young stellar populations and measure the total recent star formation rate (SFR) of nearly the entire young stellar disk. We find the global SFR(age$\leq$25 Myr)=$13.17 \substack{+0.91 \\-0.79} M_\odot/\rm yr$. Over this period, the SFR is initially very high ($23.39\substack{+2.43\\-2.11} M_\odot/\rm yr$ between 16-25 Myr ago), then monotonically decreases to a recent SFR of $5.31\substack{+0.19\\-0.17} M_\odot/\rm yr$ in the last 10 Myr. This decrease in global star formation rate over the last 25 Myr is consistent with measurements made with other SFR indicators. We discuss in detail two of the most active regions of the galaxy, which we find are responsible for 3% and 5% of the total star formation over the past 6.3 Myr.Comment: 19 pages, 11 figures, accepted for publication in Ap