First order Bragg grating filters in silicon on insulator waveguides.

The subject of this thesis is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven to investigate the variation of grating parameters with a) the period of the gratings b) the duty cycle (or mark to space ratio) of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven (this was to simulate the effects of oxidising Porous Silicon) and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the Ion as Implanted samples in the ATI, University of Surrey, which were found to have surface undulations in the order of 60 nanometres

Wettability characteristics variation of nylon 6,6 by means of CO2 laser generated surface patterns

CO2 lasers can be seen to lend themselves to materials processing applications. These types of lasers have been used extensively in research and industry with the work carried out being well documented. This work investigated the surface modification of nylon 6,6 with a CO2 laser in order to vary wettability characteristics. The wettability characteristics of the nylon 6,6 were modified by generating a number of patterns of various topography on the surface using the CO2 laser. Thereafter the as-received and modified surfaces were analysed using white light interferometry to quantify the topographical changes. Any changes in the chemical composition of the surfaces were explored with EDX and XPS analysis. To quantify the wettability characteristics as a function of laser irradiation, contact angles where determined using a sessile drop device for each sample. In this way it was possible to determine the efficacy of the CO2 laser generated topographical patterns in terms of wettability characteristics modification. It has been proposed that the increase in contact angle for the laser irradiated samples is due to a change in wetting regime from Wenzel to Cassie-Baxter

A proposed roadmap for the control of infections in wildlife using Chlamydia vaccine development in koalas Phascolarctos cinereus as a template

Vaccination strategies provide a crucial tool for managements of disease risks in wildlife, but have been utilized mostly for domestic species. However, a significant body of work has now been published describing the successful development of an anti-chlamydial vaccine for the koala Phascolarctos cinereus, Goldfuss, 1817. As such, vaccinations against these infections in the koala, can provide important insights into the use of vaccines for wildlife. Chlamydia infections in the koala have been intensively studied for over 30 years. Infections cause severe disease states, such as kerato-conjunctivitis (blindness) and reproductive tract disease (infertility), and/or mortality; and are contributing significantly to population declines. We aim to use the plethora of data available from koala chlamydial studies as a template to propose a roadmap for the development of vaccines for other wildlife species, especially in this era of antibiotic resistance. As such we have outlined the important steps that have led to significant milestones resulting in the successful development of a vaccine against an infectious disease in a non-domestic species. We hope to thus provide, not only a timely review on Chlamydia vaccines in koalas, but also an important conservation and management roadmap to help guide future researchers that are considering the development of a vaccine for a wild species.publishedVersio

Reductions of erythrocyte membrane viscoelastic coefficients reflect spectrin deficiencies in hereditary spherocytosis

Hereditary spherocytosis is a common hemolytic anemia associated with deficiencies in spectrin, the principal structural protein of the erythrocyte membrane-skeleton. We have examined 20 different individuals from 10 spherocytosis kindreds and 2 elliptocytosis kindreds to determine the effects of different levels of spectrin deficiency on the viscoelastic properties of the erythrocyte membrane. Micropipettes were used to perform single-cell micromechanical measurements of approximately 1,000 individual cells to determine the membrane elastic shear modulus, the apparent membrane bending stiffness, and whole cell recovery time constant for the different cell populations. The membrane viscosity was calculated by the product of the shear modulus and the recovery time constant. Results show correlation between the fractional reduction in shear modulus and the fractional reduction in spectrin content (determined by spectrin radioimmunoassay) and spectrin density (determined by the ratios of spectrin to band 3 on electrophoresis gels) suggesting that membrane shear elasticity is directly proportional to the surface density of spectrin on the membrane (P less than 0.001). The apparent membrane bending stiffness is also reduced in proportion to the density of spectrin (P less than 0.001). The membrane viscosity is reduced relative to control (P less than 0.001), but the nature of the relationship between spectrin density and membrane viscosity is less clearly defined. These studies document striking relationships between partial deficiencies of erythrocyte spectrin and specific viscoelastic properties of the mutant membranes

Monitoring impacts from Council Regulation (EU) No 333/2011: End-of-waste criteria for Al/Fe scrap

On 9 October 2011, Council Regulation 333/2011 came into force establishing criteria by which scrap from iron and steel, aluminium and aluminium alloys could cease to be regulated as waste. This study examines the impacts of the Regulation on scrap availability, trade flows, prices, administrative requirements and environment or human health incidents. Because no data currently distinguishes between waste and end-of-waste compliant scrap, information was collected from the EU Competent Authorities and industry using detailed surveys. Across Europe, approximately 250 companies provided responses to the industry survey (representing approximately one quarter of the membership of the scrap industry associations), with a further 15 submissions from industry associations and 25 from Competent Authorities, although the survey responses were notably skewed towards Italy. The results of the study show that more than 1,100 scrap industry companies are already using the end-of-waste criteria across Europe. Uptake is most pronounced in Italy, where over 1,000 scrap companies generate end-of-waste compliant scrap. This rapid uptake in Italy is due in part to a specific legal framework on secondary raw materials already in place before the introduction of the end-of-waste criteria. In the rest of Europe there are a further 100 scrap companies active in end-of-waste scrap. In terms of the quantity of end-of-waste compliant scrap available on the market, this study estimates that, as a lower bound, at least 15% of EU scrap steel and 10% of EU scrap aluminium is compliant. Importantly, this study has found almost no evidence that end-of-waste has caused any negative impacts on the market, whether that be to scrap quality, availability/trade or on the environment. On the contrary, quite a number of the survey participants, both from industry and Competent Authorities highlighted the perceived benefits of the introduction of end-of-waste for metal scrap. These perceived benefits include: creating a simplified regulatory framework and offering companies greater flexibility and legal certainty. Some companies identified improved scrap quality and increased sales prices. At the expert workshop participants debated several ideas for a future monitoring system. One key conclusion was that there is no urgent need to revisit monitoring in the near future, due to the relatively modest rate of uptake outside Italy and the very few, if any, negative impacts observed so far. A repeat of the industry and authorities’ surveys in 2-3 years times was deemed to be the most appropriate way to monitor end-of-waste for scrap metal, and copper scrap could be added to the scope of that exercise.JRC.J.5-Sustainable Production and Consumptio