Conclusion

Concluding analysis of the challenges of regulating PGD

Simultaneous saccharification and fermentation of steam exploded duckweed: Improvement of the ethanol yield by increasing yeast titre

This study investigated the conversion of Lemna minor biomass to bioethanol. The biomass was pre-treated by steam explosion (SE, 210 °C, 10 min) and then subjected to simultaneous saccharification and fermentation (SSF) using CellicÒ CTec 2 (20 U or 0.87 FPU gﰂ1 substrate) cellulase plus b-glucosidase (2 U gﰂ1 substrate) and a yeast inoculum of 10% (v/v or 8.0 ﰀ 107 cells mLﰂ1). At a substrate concentration of 1% (w/v) an ethanol yield of 80% (w/w, theoretical) was achieved. However at a substrate concentration of 20% (w/v), the ethanol yield was lowered to 18.8% (w/w, theoretical). Yields were considerably improved by increasing the yeast titre in the inoculum or preconditioning the yeast on steam exploded liquor. These approaches enhanced the ethanol yield up to 70% (w/w, theoretical) at a substrate concen- tration of 20% (w/v) by metabolising fermentation inhibitors

The Challenge for Youth in a Developing Bahamas

A "check up" on the Bahamas nine years post-Independence. Concern expressed about the high crime rate among young men, teenage pregnancy among young women. Predicts eight challenges to youth for the 1980s and 1990s

Observable predictions of generalised inflationary scenarios

Inflation is an early period of accelerated cosmic expansion, thought to be sourced by high energy physics. A key task today is to use the influx of increasingly precise observational data to constrain the plethora of inflationary models suggested by fundamental theories of interactions. This requires a robust theoretical framework for quantifying the predictions of such models; helping to develop such a framework is the aim of this thesis. We provide the first complete quantization of subhorizon perturbations for the well-motivated class of multi-field inflationary models with a non-trivial field metric, which we show may yield interesting signatures in the bispectrum of the Cosmic Microwave Background (CMB). The subsequent evolution of perturbations in the superhorizon epoch is then considered, via a covariant extension of the transport formalism. To develop intuition about the relationship between inflationary dynamics and the evolution of cosmic observables, we investigate analytic approximations of superhorizon perturbation evolution. The validity of these analytic results is contingent on reaching a state of adiabaticity which we discuss and illustrate in depth. We then apply our analytic methods to elucidate the types of inflationary dynamics that lead to an enhanced CMB non-Gaussianity, both in its bispectrum and trispectrum. In addition to deriving a number of new simple relations between the non-Gaussianity parameters, we explain dynamically how and why different shapes of inflationary potential lead to particular observational signatures. Candidate theories of high energy physics such as low energy effective string theory also motivate single-field modifications to the Einstein-Hilbert action. We show how a range of such corrections allow for consistency of single-field chaotic inflationary models that are otherwise in tension with observational data.Comment: PhD Thesis, Queen Mary, University of London. Supervised by Reza Tavakol. (212 pages, 31 figures

The exploitation of municipal solid waste (MSW) and related waste paper streams in the production of bioalcohol

An organic fraction from municipal solid waste (MSW) comprised 38.9% (w/w) glucose (cellulose and starch) indicating its potential as a substrate for bioalcohol production. Microscopy indicated that the fraction was rich in waste paper fibres. Much paper waste comes from shredded office paper (50.4% w/w glucose) which is unrecyclable because of poor fibre length. This, and microbiological hazards associated with the use of MSW led to its choice as model substrate for study. Saccharification of shredded paper waste was optimised by selection of Accellerase® and additional beta-glucosidase enabling digestion of 99.27% of cellulose. Sequential batch-addition of substrate permitted substrate “concentrations” equivalent to 25-30% (w/v). Saccharification was enhanced by detergent, but reduced by the presence of alcohols at over 3-4% (v/v). Steam explosion of paper slightly enhanced saccharification. However, the approach was rejected due to high energy cost, production of fermentation inhibitors at high severities, and lack of clear benefit regarding ethanol yield. Interestingly, levels of inhibitors were low compared to other pre-treated substrates and addition of paper to other substrates greatly reduced their own production of inhibitors during pre-treatment (wheat straw 60%, filter paper 95%). Larger pilot-scale (1.5-5 L) operations involved developing the batch-addition regime with a high-shear stirring capacity vessel. Additions equating to final substrate concentrations of ~65% (w/v) were achieved (from an initial 5% w/v) and facilitated high ethanol concentrations (11.6% v/v) with minimal enzyme input (3.7 FPU/g substrate). Thermal tolerance of a range of yeast strains was investigated by developing a rapid screening approach with liquid-handling robotics. This identified strains able to endure temperatures up to 40°C. Evolutionary engineering may improve tolerances to temperatures nearer to enzyme optimums (50°C). Some previously unused strains exhibited superior growth to referenced industrial strains. The above findings were integrated into a process design along with recommendations for further enhancement

IN SEARCH OF A FUNCTION FOR AN UNCHARACTERIZED CONSERVED PROTEIN IN Streptococcus sanguinis SK36

With the number of fully sequenced bacterial genomes increasing in the past 7 years, it has been discovered that a large percentage of the putative protein coding genes have no known function. This lack of knowledge leaves scientists with an incomplete understanding of bacteria. In this study, conserved hypothetical protein mutants from Streptococcus sanguinis SK36 were screened on solid media with various environmental conditions. From these screens, the candidate protein, SSA_2372, displayed a sensitivity to acidic conditions. Its homolog in Bacillus subtilis 168, BSU00030, also displayed a sensitivity to pH conditions at its acid tolerance extremes unlike its other homolog in Escherichia coli, YbcJ. When the growth rate and cell yield was acquired, the sensitivity was shown to be significant for both SSA_2372 and BSU00030 mutants. Through data mining, it was determined that Firmicutes in this homolog family COG2501 may function as a regulator for recombination protein F

The Welfare of the Child Principle and the Use of PGD under the HFEA 1990 (as amended)

This chapter discussed the impact of the HFEA Acts on the issue of embryo selection in the UK