Polymerisations in supercritical carbon dioxide

This Thesis describes the use of supercritical carbon dioxide as both a reaction solvent and processing medium for synthesis new polymeric materials. Chapter 2 details the high pressure equipment used for this body of work, as well as the analytical techniques employed. This includes equipment details for a new high pressure cell designed for measuring small angle x-ray scattering of polymers in situ. Chapter 3 describes the homopolymerisation of both methyl methacrylate and styrene in a supercritical carbon dioxide expanded phase system. Effects of molecular weight and viscosity on the final reaction product are probed in order to ascertain the most suitable types of polymers to be synthesised by this method. This is then extended to create low molecular weight block copolymers in the absence of any volatile organic solvents, with comparable properties to those produced by conventional methods. The development of the high pressure cell for measuring small angle x-ray scattering of block copolymers synthesised in a supercritical carbon dioxide dispersion polymerisation in situ is described in Chapter 4. Initial investigations showed problems with the synthesis in this new vessel, with different products obtained compared to a conventional autoclave. However, data is presented to display the suitability of certain aspects of the design and that scattering patterns can be acquire in situ during a polymerisation. Details of a second modified design are presented, with construction currently in progress. Finally, a green synthetic route to producing renewable, biodegradable and biocompatible polymers is presented in Chapter 5. By using supercritical carbon dioxide to lower the melting temperatures of the monomers, polymerisations usually conducted at temperatures in excess of 130 °C were successfully conducted at 80 °C. Through the use of a novel zirconium catalyst the tacticity of poly(lactic acid) was controlled, opening up a route to functional materials

A method for accurate detection of genomic microdeletions using real-time quantitative PCR

BACKGROUND: Quantitative Polymerase Chain Reaction (qPCR) is a well-established method for quantifying levels of gene expression, but has not been routinely applied to the detection of constitutional copy number alterations of human genomic DNA. Microdeletions or microduplications of the human genome are associated with a variety of genetic disorders. Although, clinical laboratories routinely use fluorescence in situ hybridization (FISH) to identify such cryptic genomic alterations, there remains a significant number of individuals in which constitutional genomic imbalance is suspected, based on clinical parameters, but cannot be readily detected using current cytogenetic techniques. RESULTS: In this study, a novel application for real-time qPCR is presented that can be used to reproducibly detect chromosomal microdeletions and microduplications. This approach was applied to DNA from a series of patient samples and controls to validate genomic copy number alteration at cytoband 22q11. The study group comprised 12 patients with clinical symptoms of chromosome 22q11 deletion syndrome (22q11DS), 1 patient trisomic for 22q11 and 4 normal controls. 6 of the patients (group 1) had known hemizygous deletions, as detected by standard diagnostic FISH, whilst the remaining 6 patients (group 2) were classified as 22q11DS negative using the clinical FISH assay. Screening of the patients and controls with a set of 10 real time qPCR primers, spanning the 22q11.2-deleted region and flanking sequence, confirmed the FISH assay results for all patients with 100% concordance. Moreover, this qPCR enabled a refinement of the region of deletion at 22q11. Analysis of DNA from chromosome 22 trisomic sample demonstrated genomic duplication within 22q11. CONCLUSION: In this paper we present a qPCR approach for the detection of chromosomal microdeletions and microduplications. The strategic use of in silico modelling for qPCR primer design to avoid regions of repetitive DNA, whilst providing a level of genomic resolution greater than standard cytogenetic assays. The implementation of qPCR detection in clinical laboratories will address the need to replace complex, expensive and time consuming FISH screening to detect genomic microdeletions or duplications of clinical importance

Evaluation Of Sensitivity To Chemotherapeutants In Successive Generations Of Lepeoptheirus Salmonis From A Resistant Population

There are currently reports of reduced sensitivity to certain lice treatments in different parts of Scotland and world-wide, and research is on-going into the extent and mechanisms of resistance to different treatments (Denholm et al., 2002; Sevatdal & Horsberg, 2003; Sevatdal et al., 2005). In particular, increasing evidence of resistance of Lepeophtheirus salmonis to the chemotherapeutant emamectin benzoate (Lees et al., 2008; Espedal et al., 2010) poses a serious problem to commercial farms because there are few licensed and effective treatments available

Inflationary Reheating Classes via Spectral Methods

Inflationary reheating is almost completely controlled by the Floquet indices, $\mu_k$. Using spectral theory we demonstrate that the stability bands (where $\mu_k = 0$) of the Mathieu and Lam\'e equations are destroyed even in Minkowski spacetime, leaving a fractal Cantor set or a measure zero set of stable modes in the cases where the inflaton evolves in an almost-periodic or stochastic manner respectively. These two types of potential model the expected multi-field and quantum backreaction effects during reheating.Comment: 5 pages, 2 ps figures, Revtex. Version to appear in Phys. Rev. D (Rapid Communication, July 15

One-pot synthesis of micron-sized polybetaine particles: innovative use of supercritical carbon dioxide

Polybetaines exhibit unique properties combining anti-polyelectrolyte and low protein fouling behaviour, as well as biocompatibility. To date, the synthesis of polybetaine particles >50 nm has proved to be extremely challenging with standard emulsion and dispersion techniques being unsuccessful. Here we present the first reported synthesis of micron-sized, discrete cross-linked polybetaine particles, using polymerisation in scCO2 with methanol as a co-solvent. Discrete particles are produced only when the methanol is efficiently removed in situ using scCO2 extraction. A relatively high crosslinking agent initial concentration (10 wt%) was found to result in the most well defined particles, and particle integrity reduced as the crosslinking agent initial concentration was decreased. A monomer loading of between 3.0 × 10−2 mol L−1 and 1.8 × 10−1 mol L−1 resulted in discrete micron sized particles, with significant agglomoration occuring as the monomer loading was increased further. A spherical morphology and extremely low size dispersity was observed by SEM analysis for the optimised particles. The particles were readily re-dispersed in aqueous solution and light scattering measurements confirmed their low size dispersity

Energy and environmental report. Castleland Renewal Area, Barry

This report provides a guidance of the possible routes towards improving the energy efficiency of the existing housing stock in Castleland Renewal Area, Barry. A clustering analysis focused on domestic dwellings has been developed in order to maximise the available data, creating representative groups of the larger area. Initial data has been collected and supplied by Warm Wales, thereafter complemented and expanded by the research team at the Welsh School of Architecture, where finally the information has been entered into the Energy and Environmental Prediction (EEP) model to create a database for Castleland. The analysis has been developed out of the collaborative work between Warm Wales and the Low Carbon Research Institute, at the Welsh School of Architecture (WSA), Cardiff University

Controlled aqueous polymerization of acrylamides and acrylates and “in situ” depolymerization in the presence of dissolved CO2

Aqueous copper-mediated radical polymerization of acrylamides and acrylates in carbonated water resulted in high monomer conversions (t t > 10 min). The regenerated monomer was characterized and repolymerized following deoxygenation of the resulting solutions to reyield polymers in high conversions that exhibit low dispersities

Calculating the solar potential of the urban fabric with SketchUp and HTB2

This paper introduces a new tool for analysing annual solar insolation potentials for façades and roofs at an urban scale using Trimble SketchUp and the dynamic simulation model HTB2. The tool is in the form of a plugin which 1) generates shading masks for every façade and roof in a model, 2) exports geometries to HTB2 for analysis, 3) invokes HTB2 from within SketchUp, and 4) returns outputs into SketchUp for review. Its capability to calculate the effects of complex terrain (imported from Google Earth) on façade and roof solar insolation levels is demonstrated. Case studies of the tool applied to both urban and rural areas of Wales and Europe are examined and results discussed. The simplicity of the tool in performing complex solar potential analyses is demonstrated, and its broader application as an analysis tool for calculating urban energy demands are presented

Low temperature district heating network planning with the focus on distribution energy losses

An integrated conceptual planning framework has been developed to assist designing for high resource efficient, low carbon urban district heating systems. This paper focuses on distribution energy losses of a district heating system for an existing urban settlement. The planning framework consists of a methodological approach and a set of simulation tools to investigate two scenarios – low temperature and high temperature district heating networks. In this framework a dynamic building simulation program predicting energy demand of a case study area, an industrial software tool for piping systems design, and a mathematical optimization tool are integrated for assessing energy and exergy losses. Some preliminary results are shown at the end of the paper demonstrating the benefits of low temperature district heating networks and potential of the planning framework