In situ studies of spin-coated polymer films

Spin-coating is a facile, straightforward, solution processing technique for the production of uniform thin films, which has been utilised for a wide range of applications including organic electronic and photonic devices, sensors, membranes and optical coatings. Many of the applications of spin-coated polymer films utilise the propensity of polymers to self-assemble, resulting in the formation of well-ordered, intricate morphologies that evolve towards thermodynamic equilibrium. Understanding the interplay between processes such as phase-separation and crystallisation, which control the final morphology, has therefore been the topic of intense theoretical and experimental studies in the field of polymer science. In particular the potential of spun-cast organic electronic devices to help alleviate the world's dependence upon fossil fuels in terms of energy generation and energy efficiencies has driven the need for greater control over the final morphology, in order to produce more efficient devices. I have developed the technique of stroboscopic microscopy, which facilitates direct imaging during spin-coating, allowing us to directly observe, in real-time, the processes of self-assembly at the microscale. I have advanced the technique to operate in three different modes, which allow observations of topography, composition and crystallisation. This thesis presents the direct observations of self-assembly processes that occur during the spin-coating of model polymer systems [polystyrene:poly(methyl methacrylate) and polystyrene:poly(ethylene glycol)], systems relevant to organic electronics [polystyrene:poly 9,9’-dioctlyflourene] and polystyrene colloidal dispersions. A number of key parameters have been investigated including the effects of; rotation rate, composition, polydispersity and the interplay between crystallisation and phase separation. The observation that of have been made may be utilised to either, rationally design processing conditions that will allow targeted morphologies to be attained or information obtained in real-time may be used to direct and control self-assembly processes in order to achieve desired morphologies

Variation in C - reactive protein response according to host and mycobacterial characteristics in active tuberculosis

BACKGROUND: The C - reactive protein (CRP) response is often measured in patients with active tuberculosis (TB) yet little is known about its relationship to clinical features in TB, or whether responses differ between ethnic groups or with different Mycobacterium tuberculosis (M.tb) strain types. We report the relationship between baseline serum CRP prior to treatment and disease characteristics in a metropolitan population with TB resident in a low TB incidence region. METHODS: People treated for TB at four London, UK sites between 2003 and 2014 were assessed and data collected on the following characteristics: baseline CRP level; demographics (ethnicity, gender and age); HIV status; site of TB disease; sputum smear (in pulmonary cases) and culture results. The effect of TB strain-type was also assessed in culture-positive pulmonary cases using VNTR typing data. RESULTS: Three thousands two hundred twenty-two patients were included in the analysis of which 72 % had a baseline CRP at or within 4 weeks prior to starting TB treatment. CRP results were significantly higher in culture positive cases compared to culture negative cases: median 49 mg/L (16-103 mg/L) vs 19 mg/L (IQR 5-72 mg/L), p = <0.001. In those with pulmonary disease, smear positive cases had a higher CRP than smear negative cases: 67 mg/L (31-122 mg/L) vs 24 mg/L (7-72 mg/L), p < 0.001. HIV positive cases had higher baseline CRPs than HIV negative cases: 75 mg/L (26-136 mg/L) vs 37 mg/L (10-88 mg/L), p <0.001. Differing sites of disease were associated with differences in baseline CRP: locations that might be expected to have a high mycobacterial load (e.g. pulmonary disease and disseminated disease) had a significantly higher CRP than those such as skin, lymph node or CNS disease, where the mycobacterial load is typically low in HIV negative subjects. In a multivariable log-scale linear regression model adjusting for host characteristics and M.tb strain type, infection with the East African Indian strain was associated with significantly lower baseline-CRP (fold-change in CRP 0.51 (0.34-0.77), p < 0.01). CONCLUSIONS: Host and mycobacterial factors are strongly associated with baseline CRP response in tuberculosis. This analysis suggests that there are important differences in innate immune response according to ethnicity, Mtb strain type and site of disease. This may reflect differing mycobacterial loads or host immune responses

Does 1,8-diiodooctane affect the aggregation state of PC71BM in solution?

1,8-Diiodooctane (DIO) is an additive used in the processing of organic photovoltaics and has previously been reported, on the basis of small-angle X-ray scattering (SAXS) measurements, to deflocculate nano-aggregates of [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) in chlorobenzene. We have critically re-examined this finding in a series of scattering measurements using both X-rays and neutrons. With SAXS, we find that the form of the background solvent scattering is influenced by the presence of DIO, that there is substantial attenuation of the X-rays by the background solvent and that there appears to be beam-induced aggregation. All three factors call into question the suitability of SAXS for measurements on these samples. By contrast, small-angle neutron scattering (SANS) measurements, performed at concentrations of 15 mg ml−1 up to and including 40 mg ml−1, show no difference in the aggregation state for PC71BM in chlorobenzene with and without 3% DIO; we find PC71BM to be molecularly dissolved in all solvent cases. In situ film thinning measurements of spin-coated PC71BM solution with the DIO additive dry much slower. Optical imaging shows that the fullerene films possess enhanced molecular mobility in the presence of DIO and it is this which, we conclude, improves the nanomorphology and consequently solar cell performance. We propose that any compatible high boiling solvent would be expected to show the same behaviour

Terrorists, rioters and crocodiles: The political symbolism of an Olympic monster

This is a post-peer-review, pre-copyedit version of an article published in British Politics. The definitive publisher-authenticated version - British Politics, 2014, 9(2), pp. 161-181 - is available online at: http://www.palgrave-journals.com/bp/journal/v9/n2/full/bp201317a.htmlIn August 2005, just a month after the announcement that London had succeeded in its bid to host the 2012 Olympic Games, the UK national press witnessed a brief rash of stories alleging the presence of a crocodile or similar water monster lurking beneath the surface of the River Lea – the river that runs from the town of Luton in Bedfordshire down to join the Thames adjacent to the Olympic site. This story re-emerged in November 2011 when a campaigner against the environmental impact of the Olympics on the river area claimed to have seen further evidence of crocodilian activity. This paper will explore the reasons for the proliferation of this story, in terms both of its function as a metonymic news-hook (it opened up directly related concerns as to the impact, organization and security of the Games) and of its metaphorical significance (its incarnation of a superstructure’s fears of an emerging threat of a monstrous underclass – one which might at once comprise terrorists, rioters and anti-establishment campaigners). It will conclude by suggesting that this monstrous myth might hold within it the possibility of the convergence of populist news media and popular democracy

The effect of cartilage and bone density of mushroom-shaped, photooxidized, osteochondral transplants: an experimental study on graft performance in sheep using transplants originating from different species

BACKGROUND: Differences in overall performance of osteochondral photooxidized grafts were studied in accordance of their species origin and a new, more rigorous cleansing procedure using alcohol during preparation. METHODS: Photooxidized mushroom-shaped grafts of bovine, ovine, human and equine origin were implanted in the femoral condyles of 32 sheep (condyles: n = 64). No viable chondrocytes were present at the time of implantation. Grafts were evaluated at 6 months using plastic embedded sections of non-decalcified bone and cartilage specimens. Graft incorporation, the formation of cyst-like lesions at the base of the cartilage junction as well as cartilage morphology was studied qualitatively, semi-quantitatively using a score system and quantitatively by performing histomorphometrical measurements of percentage of bone and fibrous tissue of the original defects. For statistical analysis a factorial analysis of variance (ANOVA- test) was applied. RESULTS: Differences of graft performance were found according to species origin and cleansing process during graft preparation. According to the score system cartilage surface integrity was best for equine grafts, as well as dislocation or mechanical stability. The equine grafts showed the highest percentage for bone and lowest for fibrous tissue, resp. cystic lesions. The new, more rigorous cleansing process decreased cartilage persistence and overall graft performance. CONCLUSION: Performance of grafts from equine origin was better compared to bovine, ovine and human grafts. The exact reason for this difference was not proven in the current study, but could be related to differences in density of cartilage and subchondral bone between species

The RESPECT Study for consensus on global bereavement care after stillbirth.

OBJECTIVE: To develop global consensus on a set of evidence-based core principles for bereavement care after stillbirth. METHODS: A modified policy-Delphi methodology was used to consult international stakeholders and healthcare workers with experience in stillbirth between September 2017 and October 2018. Five sequential rounds involved two expert stakeholder meetings and three internet-based surveys, including a global internet-based survey targeted at healthcare workers in a wide range of settings. RESULTS: Initially, 23 expert stakeholders considered 43 evidence-based themes derived from systematic reviews, identifying 10 core principles. The global survey received 236 responses from participants in 26 countries, after which nine principles met a priori criteria for inclusion. The final stakeholder meeting and internet-based survey of all participants confirmed consensus on eight core principles. Highest quality bereavement care should be enabled through training of healthcare staff to reduce stigma and establish respectful care, including acknowledgement and support for grief responses, and provision for physical and psychologic needs. Women and families should be supported to make informed choices, including those concerning their future reproductive health. CONCLUSION: Consensus was established for eight principles for stillbirth bereavement care. Further work should explore implementation and involve the voices of women and families globally

Ligand-Directed Self-Assembly of Organic-Semiconductor/Quantum-Dot Blend Films Enables Efficient Triplet Exciton-Photon Conversion

Blends comprising organic semiconductors and inorganic quantum dots (QDs) are relevant for many optoelectronic applications and devices. However, the individual components in organic-QD blends have a strong tendency to aggregate and phase-separate during film processing, compromising both their structural and electronic properties. Here, we demonstrate a QD surface engineering approach using electronically active, highly soluble semiconductor ligands that are matched to the organic semiconductor host material to achieve well-dispersed inorganic–organic blend films, as characterized by X-ray and neutron scattering, and electron microscopies. This approach preserves the electronic properties of the organic and QD phases and also creates an optimized interface between them. We exemplify this in two emerging applications, singlet-fission-based photon multiplication (SF-PM) and triplet–triplet annihilation-based photon upconversion (TTA-UC). Steady-state and time-resolved optical spectroscopy shows that triplet excitons can be transferred with near unity efficiently across the organic–inorganic interface, while the organic films maintain efficient SF (190% yield) in the organic phase. By changing the relative energy between organic and inorganic components, yellow upconverted emission is observed upon 790 nm NIR excitation. Overall, we provide a highly versatile approach to overcome longstanding challenges in the blending of organic semiconductors with QDs that have relevance for many optical and optoelectronic applications