3 resultados para STIMULI-RESPONSIVE POLYMERS

em CORA - Cork Open Research Archive - University College Cork - Ireland


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Can my immediate physical environment affect how I feel? The instinctive answer to this question must be a resounding “yes”. What might seem a throwaway remark is increasingly borne out by research in environmental and behavioural psychology, and in the more recent discipline of Evidence-Based Design. Research outcomes are beginning to converge with findings in neuroscience and neurophysiology, as we discover more about how the human brain and body functions, and reacts to environmental stimuli. What we see, hear, touch, and sense affects each of us psychologically and, by extension, physically, on a continual basis. The physical characteristics of our daily environment thus have the capacity to profoundly affect all aspects of our functioning, from biological systems to cognitive ability. This has long been understood on an intuitive basis, and utilised on a more conscious basis by architects and other designers. Recent research in evidence-based design, coupled with advances in neurophysiology, confirm what have been previously held as commonalities, but also illuminate an almost frightening potential to do enormous good, or alternatively, terrible harm, by virtue of how we make our everyday surroundings. The thesis adopts a design methodology in its approach to exploring the potential use of wireless sensor networks in environments for elderly people. Vitruvian principles of “commodity, firmness and delight” inform the research process and become embedded in the final design proposals and research conclusions. The issue of person-environment fit becomes a key principle in describing a model of continuously-evolving responsive architecture which makes the individual user its focus, with the intention of promoting wellbeing. The key research questions are: What are the key system characteristics of an adaptive therapeutic single-room environment? How can embedded technologies be utilised to maximise the adaptive and therapeutic aspects of the personal life-space of an elderly person with dementia?.

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The objective of this thesis is the exploration and characterisation of the nanoscale electronic properties of conjugated polymers and nanocrystals. In Chapter 2, the first application of conducting-probe atomic force microscopy (CP-AFM)-based displacement-voltage (z-V) spectroscopy to local measurement of electronic properties of conjugated polymer thin films is reported. Charge injection thresholds along with corresponding single particle gap and exciton binding energies are determined for a poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] thin film. By performing measurements across a grid of locations on the film, a series of exciton binding energy distributions are identified. The variation in measured exciton binding energies is in contrast to the smoothness of the film suggesting that the variation may be attributable to differences in the nano-environment of the polymer molecules within the film at each measurement location. In Chapter 3, the CP-AFM-based z-V spectroscopy method is extended for the first time to local, room temperature measurements of the Coulomb blockade voltage thresholds arising from sequential single electron charging of 28 kDa Au nanocrystal arrays. The fluid-like properties of the nanocrystal arrays enable reproducible formation of nanoscale probe-array-substrate junctions, allowing the influence of background charge on the electronic properties of the array to be identified. CP-AFM also allows complementary topography and phase data to be acquired before and after spectroscopy measurements, enabling comparison of local array morphology with local measurements of the Coulomb blockade thresholds. In Chapter 4, melt-assisted template wetting is applied for the first time to massively parallel fabrication of poly-(3-hexylthiophene) nanowires. The structural characteristics of the wires are first presented. Two-terminal electrical measurements of individual nanowires, utilising a CP-AFM tip as the source electrode, are then used to obtain the intrinsic nanowire resistivity and the total nanowire-electrode contact resistance subsequently allowing single nanowire hole mobility and mean nanowire-electrode barrier height values to be estimated. In Chapter 5, solution-assisted template wetting is used for fabrication of fluorene-dithiophene co-polymer nanowires. The structural characteristics of these wires are also presented. Two-terminal electrical measurements of individual nanowires indicate barrier formation at the nanowire-electrode interfaces and measured resistivity values suggest doping of the nanowires, possibly due to air exposure. The first report of single conjugated polymer nanowires as ultra-miniature photodetectors is presented, with single wire devices yielding external quantum efficiencies ~ 0.1 % and responsivities ~ 0.4 mA/W under monochromatic illumination.

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Through the recognition of potentially harmful stimuli, Toll-like receptors (TLRs) initiate the innate immune response and induce the expression of hundreds of immune and pro-inflammatory genes. TLRs are critical in mounting a defence against invading pathogens however, strict control of TLR signalling is vital to prevent host damage from excessive or prolonged immune activation. In this thesis the role of the IκB protein Bcl (B-cell lymphoma)-3 in the regulation of TLR signalling is investigated. Bcl3-/- mice and cells are hyper responsive to TLR stimulation and are defective in LPS tolerance. Bcl-3 interacts with and blocks the ubiquitination of homodimers of the NF-κB subunit, p50. Through stabilisation of inhibitory p50 homodimers, Bcl-3 negatively regulates NF-κB dependent inflammatory gene transcription following TLR activation. Firstly, we investigated the nature of the interaction between Bcl-3 and p50 and using peptide array technology. Key amino acids required for the formation of the p50:Bcl-3 immunosuppressor complex were identified. Furthermore, we demonstrate for the first time that interaction between Bcl-3 and p50 is necessary and sufficient for the anti-inflammatory properties of Bcl-3. Using the data generated from peptide array analysis we then generated cell permeable peptides designed to mimic Bcl-3 function and stabilise p50 homodimers. These Bcl-3 derived peptides are potent inhibitors of NF-κB dependent transcription activity in vitro and provide a solid basis for the development of novel gene-specific approaches in the treatment of inflammatory diseases. Secondly, we demonstrate that Bcl-3 mediated regulation of TLR signalling is not limited to NF-κB and identify the MAK3K Tumour Progression Locus (Tpl)-2 as a new binding partner of Bcl-3. Our data establishes role for Bcl-3 as a negative regulator of the MAPK-ERK pathway.