Single link flexible beam testbed project

This thesis describes the single link flexible beam testbed at the CLaMS laboratory in terms of its hardware, software, and linear model, and presents two controllers, each including a hub angle proportional-derivative (PD) feedback compensator and one augmented by a second static gain full state feedback loop, based upon a synthesized strictly positive real (SPR) output, that increases specific flexible mode pole damping ratios w.r.t the PD only case and hence reduces unwanted residual oscillation effects. Restricting full state feedback gains so as to produce a SPR open loop transfer function ensures that the associated compensator has an infinite gain margin and a phase margin of at least (-90, 90) degrees. Both experimental and simulation data are evaluated in order to compare some different observer performance when applied to the real testbed and to the linear model when uncompensated flexible modes are included

Dental and nondental stem cell based regeneration of the craniofacial region: a tissue based approach

Craniofacial reconstruction may be a necessary treatment for those who have been affected by trauma, disease, or pathological developmental conditions. The use of stem cell therapy and tissue engineering shows massive potential as a future treatment modality. Currently in the literature, there is a wide variety of published experimental studies utilising the different stem cell types available and the plethora of available scaffold materials. This review investigates different stem cell sources and their unique characteristics to suggest an ideal cell source for regeneration of individual craniofacial tissues. At present, understanding and clinical applications of stem cell therapy remain in their infancy with numerous challenges to overcome. In spite of this, the field displays immense capacity and will no doubt be utilised in future clinical treatments of craniofacial regeneration

Managing an Unstable Housing Market

AbstractIn this paper it is intended to place the recent experience of the Irish housing market in the context of economic and property market cycles, how these interact over a property cycle and lessons from recent policy experience including interventions in the housing area. In spatial terms the currenthousing market can be seen as the result of an ad-hoc development led urban growth pattern which contributed to a dispersed development pattern with problems in oversupply. It is clear that alternative options exist to this approach and that evidence based management systems in terms of planning, development and financial decisions will be required to reduce the severity of future property market corrections. The incidence of rapidly increasing residential property prices has been a feature of many international economies in the past decade. This has resulted in house price surges and corrections across much of the industrialised world. Factors associated with such surges include growth in housing demand often supported by relaxed monetary policy stances, planning and zoning systems and fiscal regimes which encourage the investment in residential property acquisition anddevelopment. The falling prices for housing in Ireland in 2007-2010 nationally has created a stagnating effect with purchasers reluctant to enter the market while the price correction is worked through. In turn suppliers, construction interests and vendors are highly reluctant to accept lower bid prices in the market due to often unrealistic expectations created during the long boom. The result of oversupply is falling prices, reduced occupation demand and decreased investor demand, leading to lower building activity and profitability. In addition the banking and liquidity crisis have contributed to a radical deterioration in economic circumstances and increasing out-migration. As part of the Urban Environment Project at UCD this working paper considers the current evidence of a market correction and oversupply in the Dublin region and Ireland based on data available up to March 2010 including the authors’ working projections for 2010

Highly efficient p-i-n perovskite solar cells that endure temperature variations

Daily temperature variations induce phase transitions and lattice strains in halide perovskites, challenging their stability in solar cells. We stabilised the perovskite black phase and improved the solar cell performance using the ordered dipolar structure of β-poly(1,1-difluoroethylene) to control the perovskite film crystallisation and the energy alignment. We demonstrated p-i-n perovskite solar cells with a record power conversion efficiency of 24.6% over 18 square millimetres and 23.1% over 1 square centimetre, which retained 96% and 88% of the efficiency after 1000-hours 1-sun maximum power point tracking at 25 and 75 °C, respectively. Devices under rapid thermal cycling between −60 °C and +80 °C showed no sign of fatigue, demonstrating the impact of the ordered dipolar structure on the operational stability of perovskite solar cells

Development of a Selective Inhibitor for Kv1.1 Channels Prevalent in Demyelinated Nerves

Members of the voltage-gated K+ channel subfamily (Kv1), involved in regulating transmission between neurons or to muscles, are associated with human diseases and, thus, putative targets for neurotherapeutics. This applies especially to those containing Kv1.1 α subunits which become prevalent in murine demyelinated axons and appear abnormally at inter-nodes, underlying the perturbed propagation of nerve signals. To overcome this dysfunction, akin to the consequential debilitation in multiple sclerosis (MS), small inhibitors were sought that are selective for the culpable hyper-polarising K+ currents. Herein, we report a new semi-podand – compound 3 – that was designed based on the modelling of its interactions with the extracellular pore region in a deduced Kv1.1 channel structure. After synthesis, purification, and structural characterisation, compound 3 was found to potently (IC50 = 8 µM) and selectively block Kv1.1 and 1.6 channels. The tested compound showed no apparent effect on native Nav and Cav channels expressed in F-11 cells. Compound 3 also extensively and selectively inhibited MS-related Kv1.1 homomer but not the brain native Kv1.1- or 1.6-containing channels. These collective findings highlight the therapeutic potential of compound 3 to block currents mediated by Kv1.1 channels enriched in demyelinated central neurons

Radiation Hardness of Perovskite Solar Cells Based on Aluminum‐Doped Zinc Oxide Electrode Under Proton Irradiation

Due to their high specific power and potential to save both weight and stow volume, perovskite solar cells have gained increasing interest to be used for space applications. However, before they can be deployed into space, their resistance to ionizing radiations such as high‐energy protons must be demonstrated. In this report, we investigate the effect of 150 keV protons on the performance of perovskite solar cells based on aluminium‐doped zinc oxide (AZO) transparent conducting oxide (TCO). Record power conversion efficiency of 15% and 13.6% were obtained for cells based on AZO under AM1.5G and AM0 illumination, respectively. We demonstrate that perovskite solar cells can withstand proton irradiation up to 1013 protons.cm−2 without significant loss in efficiency. At this irradiation dose, Si or GaAs solar cells would be completely or severely degraded when exposed to 150 keV protons. From 1014 protons.cm−2, a decrease in short‐circuit current of the perovskite cells is observed, which is consistent with interfacial degradation due to deterioration of the Spiro‐OMeTAD HTL during proton irradiation. Using a combination of non‐destructive characterization techniques, results suggest that the structural and optical properties of perovskite remain intact up to high fluence levels. Although shallow trap states are induced by proton irradiation in perovskite bulk at low fluence levels, they can release charges efficiently and are not detrimental to the cell's performance. This work highlights the potential of perovskite solar cells based on AZO TCO to be used for space applications and give a deeper understanding of interfacial degradation due to proton irradiation

Proton Radiation Hardness of Perovskite Solar Cells Utilizing a Mesoporous Carbon Electrode

Funder: Airbus Endeavr WalesFunder: Alexander von Humboldt FoundationWhen designing spacefaring vehicles and orbital instrumentation, the onboard systems such as microelectronics and solar cells require shielding to protect them from degradation brought on by collisions with high‐energy particles. Perovskite solar cells (PSCs) have been shown to be much more radiation stable than Si and GaAs devices, while also providing the ability to be fabricated on flexible substrates. However, even PSCs have their limits, with higher fluences being a cause of degradation. Herein, a novel solution utilizing a screen‐printed, mesoporous carbon electrode to act bi‐functionally as an encapsulate and the electrode is presented. It is demonstrated that the carbon electrode PSCs can withstand proton irradiation up to 1 × 1015 protons cm−2 at 150 KeV with negligible losses (<0.07%) in power conversion efficiency. The 12 μm thick electrode acts as efficient shielding for the perovskite embedded in the mesoporous TiO2. Through Raman and photoluminescence spectroscopy, results suggest that the structural properties of the perovskite and carbon remain intact. Simulations of the device structure show that superior radiation protection comes in conjunction with good device performance. This work highlights the potential of using a carbon electrode for future space electronics which is not limited to only solar cells

Trans-Species Polymorphism and Selection in the MHC Class II DRA Genes of Domestic Sheep

Highly polymorphic genes with central roles in lymphocyte mediated immune surveillance are grouped together in the major histocompatibility complex (MHC) in higher vertebrates. Generally, across vertebrate species the class II MHC DRA gene is highly conserved with only limited allelic variation. Here however, we provide evidence of trans-species polymorphism at the DRA locus in domestic sheep (Ovis aries). We describe variation at the Ovar-DRA locus that is far in excess of anything described in other vertebrate species. The divergent DRA allele (Ovar-DRA*0201) differs from the sheep reference sequences by 20 nucleotides, 12 of which appear non-synonymous. Furthermore, DRA*0201 is paired with an equally divergent DRB1 allele (Ovar-DRB1*0901), which is consistent with an independent evolutionary history for the DR sub-region within this MHC haplotype. No recombination was observed between the divergent DRA and B genes in a range of breeds and typical levels of MHC class II DR protein expression were detected at the surface of leukocyte populations obtained from animals homozygous for the DRA*0201, DRB1*0901 haplotype. Bayesian phylogenetic analysis groups Ovar-DRA*0201 with DRA sequences derived from species within the Oryx and Alcelaphus genera rather than clustering with other ovine and caprine DRA alleles. Tests for Darwinian selection identified 10 positively selected sites on the branch leading to Ovar-DRA*0201, three of which are predicted to be associated with the binding of peptide antigen. As the Ovis, Oryx and Alcelaphus genera have not shared a common ancestor for over 30 million years, the DRA*0201 and DRB1*0901 allelic pair is likely to be of ancient origin and present in the founding population from which all contemporary domestic sheep breeds are derived. The conservation of the integrity of this unusual DR allelic pair suggests some selective advantage which is likely to be associated with the presentation of pathogen antigen to T-cells and the induction of protective immunity