Aziridine-Metathesis based Approaches to Alkaloid Synthesis

The aim of the project is to synthesise (-)-morphine utilising aziridine and metathesischemistry. The thesis is divided into three chapters.Chapter 1 provides brief reviews on the subjects of total synthesis of morphine; ringrearrangementmetathesis (RRM) and regioselective ring-opening of aziridines.Chapter 2 focuses on the research findings in the past three years. Two routes, A and B,were investigated in attempts to synthesise morphine (Scheme 1). In route A, sulfonylcyclopentene II was prepared from ring-closing metathesis of a diene precursor, whichwas synthesised from lithiated cinnamylsulfone and butadiene monoxide. Subsequently,RRM reactions of several [alpha]-SO2Ph allyl derivatives of II were investigated and someinteresting results were obtained. The synthesis of 2,3-trans vinylaziridine III wasachieved in seven steps beginning with a Grignard reaction of (4-methoxyphenyl)magnesium bromide with butadiene monoxide. Subsequently, somehighly regioselective ring-opening reactions of III with sulfur-stabilised anionicnucleophiles were achieved. However, in an attempt to synthesise compound I from IIand III, no reaction was observed. This led to the investigation of route B, in which fivemethods for the synthesis of compound IV were investigated. The practical approachdeployed a novel Al-mediated substitution of the 4-tosyl group of the tosyltetrahydropyridine counterpart of IV, prepared from V and III, with a phenylthio group.Chapter 3 provides the experimental details and characterisation data.Imperial Users onl

Seismic Ray Impedance Inversion

This thesis investigates a prestack seismic inversion scheme implemented in the ray parameter domain. Conventionally, most prestack seismic inversion methods are performed in the incidence angle domain. However, inversion using the concept of ray impedance, as it honours ray path variation following the elastic parameter variation according to Snell’s law, shows the capacity to discriminate different lithologies if compared to conventional elastic impedance inversion. The procedure starts with data transformation into the ray-parameter domain and then implements the ray impedance inversion along constant ray-parameter profiles. With different constant-ray-parameter profiles, mixed-phase wavelets are initially estimated based on the high-order statistics of the data and further refined after a proper well-to-seismic tie. With the estimated wavelets ready, a Cauchy inversion method is used to invert for seismic reflectivity sequences, aiming at recovering seismic reflectivity sequences for blocky impedance inversion. The impedance inversion from reflectivity sequences adopts a standard generalised linear inversion scheme, whose results are utilised to identify rock properties and facilitate quantitative interpretation. It has also been demonstrated that we can further invert elastic parameters from ray impedance values, without eliminating an extra density term or introducing a Gardner’s relation to absorb this term. Ray impedance inversion is extended to P-S converted waves by introducing the definition of converted-wave ray impedance. This quantity shows some advantages in connecting prestack converted wave data with well logs, if compared with the shearwave elastic impedance derived from the Aki and Richards approximation to the Zoeppritz equations. An analysis of P-P and P-S wave data under the framework of ray impedance is conducted through a real multicomponent dataset, which can reduce the uncertainty in lithology identification.Inversion is the key method in generating those examples throughout the entire thesis as we believe it can render robust solutions to geophysical problems. Apart from the reflectivity sequence, ray impedance and elastic parameter inversion mentioned above, inversion methods are also adopted in transforming the prestack data from the offset domain to the ray-parameter domain, mixed-phase wavelet estimation, as well as the registration of P-P and P-S waves for the joint analysis. The ray impedance inversion methods are successfully applied to different types of datasets. In each individual step to achieving the ray impedance inversion, advantages, disadvantages as well as limitations of the algorithms adopted are detailed. As a conclusion, the ray impedance related analyses demonstrated in this thesis are highly competent compared with the classical elastic impedance methods and the author would like to recommend it for a wider application

Comment: Bayesian Checking of the Second Level of Hierarchical Models: Cross-Validated Posterior Predictive Checks Using Discrepancy Measures

Comment: Bayesian Checking of the Second Level of Hierarchical Models [arXiv:0802.0743]Comment: Published in at http://dx.doi.org/10.1214/07-STS235B the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Reactor antineutrino experiments

Neutrinos are elementary particles in the standard model of particle physics. There are 3 flavors of neutrinos that oscillate among themselves. Their oscillation can be described by a 3$\times$3 unitary matrix, containing three mixing angles $\theta_{12}$, $\theta_{23}$, $\theta_{13}$, and one CP phase. Both $\theta_{12}$ and $\theta_{23}$ are known from previous experiments. $\theta_{13}$ was unknown just two years ago. The Daya Bay experiment gave the first definitive non-zero value in 2012. An improved measurement of the oscillation amplitude $\sin^{2}2(\theta_{13})$ = $0.090^{+0.008}_{-0.009}$ and the first direct measurement of the $\bar\nu_{e}$ mass-squared difference $\mid$$\Delta m^2_{ee}$$\mid$ = $(2.59^{+0.19}_{-0.20})\times10^{-3} \rm eV^{2}$ were obtained recently. The large value of $\theta_{13}$ boosts the next generation of reactor antineutrino experiments designed to determine the neutrino mass hierarchy, such as JUNO and RENO-50

Determination of the distribution of water droplet sizes in butter and margarine using pulsed field gradient-NMR and confocal scanning laser microscopy : this thesis was presented in partial fulfillment of the requirements for [the] degree of Master of Science in Chemistry at Massey University

PFG-NMR has been used to determine the distribution of water droplets in emulsions. Especially, it has been used to measure the samples with high optical dense systems and highly viscous systems Butters and Margarines). To refine the method, the optimum measuring condition was investigated. It included delay time (Δ) between the field gradient pulses, τ null (τ0), gradient strength (G), water self-diffusion coefficients (D) and sampling techniques. Under the optimum conditions the water droplet size distributions of commercial butters, experimental butters and margarines were measured. Experimental results showed that PFG-NMR is an accurate, fast method to determine the water droplet size distributions of the butters and margarines. Also, it is can be used to investigate the properties of dispersed phase in emulsions. Especially, the method is suitable not only in the laboratory but also in the factory environment. The method was able to distinguish different distributions in butters of the same water content but with different manufacturing techniques. Differences in the distributions of water droplets were also obtained when comparing butters made by the same manufacturing technique but with different water contents. To confirm the results from PFG-NMR, confocal scanning laser microscopy (CSLM) was chosen to determine the droplet size distributions and the moisture contents of samples. Comparison between PFG-NMR and CSLM shows limitations in the latter techniques and its uses are limited