This thesis is concerned with the growth and dissolution of gypsum and analogous crystalline materials, with the aim of understanding the kinetic and mechanistic processes at the mineral-solution interface. The research conducted was a collaborative project sponsored by Saint-Gobain Gypsum. First, an image processing (IP) software package was developed to meet highly specialised IP needs and expedite the extraction of vital surface information from images produced in the growth and dissolution studies carried out in this thesis. A simple but powerful morphological analysis of characteristic etch pit features formed on the basal plane of gypsum was proposed, to aid the determination of intrinsic dissolution kinetics. Limiting the study to short times produced microscopic active features, which exhibited high and quantitative mass transport rates. At early times, the reaction was surface controlled, with the edge planes dominating the process, revealing anisotropic step propagation kinetics. With time, an increased contribution from mass transport was observed, suggesting that at later times, the basal plane dominated reaction kinetics. Common ion effects indicated a greater impact of Ca2+ than SO42- in reducing dissolution rates while inert ions enhanced dissolution in a directionspecific way. With this approach, microscopic phenomena were related to macroscopic measurements thus reconciling experimental length scales. Dissolution of the basal (010) and edge (001) surfaces of gypsum and polycrystalline anhydrite, were probed at the bulk scale by coupling the channel flow cell (CFC) technique which displays high mass transport rates, with off-line spectrometric measurements of dissolved Ca2+. Quantitative modelling of the diffusion-reaction within the CFC yielded a linear rate law for the dissolution process. Rates from the basal plane and anhydrite were found to be consistent with other bulk measurements, while the highly reactive edge plane exhibited high rates indicating a transport-limited process. Sodium trimetaphosphate, a common humid-creep inhibitor was found to significantly retard basal plane dissolution rates. Further CFC studies were carried out on industrially-relevant, chemically modified CaSO4 based materials, using a simple flux approach. It was found that models proposing a dissolution-precipitation pathway as the mode of action of humid-creep inhibitors were less plausible than those proposing a surface binding pathway. Finally, the influence of solution stoichiometry, r = (aCa2+ / aSO42-) on the growth kinetics of microscopic gypsum crystals was determined at a constant supersaturation. Crystal growth was found to be entirely controlled by surface kinetics over the range of r, with the edge planes dominating the process. The highest lateral rates were found at r = 1, diminishing sharply at r ≠ 1, and indicating strong plane-specific dependence on Ca2+ and SO42- availability. Additionally, dramatic changes in the morphology of grown crystals were observed. Propagation of steps on the basal face revealed a complex polynuclear layer-by-layer growth process for this surface. Macroscopic growth rates compared well to previous bulk measurements indicating that the approach used provided a comprehensive multi-scale view of gypsum growth processes.

This work describes the controlled organocatalytic ring-opening polymerisation (ROP) of cyclic carbonates with pendant groups for the preparation of functional aliphatic poly(carbonate)s and poly(estercarbonate) s. Their subsequent post-polymerisation functionalisations were studied yielding a range of functional aliphatic poly(carbonate)s. Chapter 1 reviews the preparation of cyclic carbonates with pendant functionalities, their ring-opening polymerisation and the postpolymerisation modifications of the resulting poly(carbonate)s. The properties and some applications of functional poly(carbonate)s are also discussed. Chapter 2, 3 and 4 describe the controlled ring-opening polymerisation of allyl- functional cyclic carbonate MAC (5-Methyl-5-allyloxycarbonyl-1,3- dioxan-2-one) and propargyl- functional cyclic carbonate MPC (5-Methyl-5- propargyloxycarbonyl-1,3-dioxan-2-one) using organic catalysts. Successful functionalisation of allyl-functional poly(carbonate)s was achieved via radical addition of thiol-containing molecules to the pendant allyl esters (Chapter 2), while functionalisation of propargyl-functional poly(carbonate)s was realised via the Huisgen 1,3-dipolar cycloaddition of azides to the pendant propargyl groups (Chapter 3). In addition, the copolymerisation of MAC and MPC and the subsequent orthogonal functionalisation of a copolymer was investigated (Chapter 4). Chapter 5 describes the copolymerisation of MAC (and MPC) with stereopure lactide, with resulting copolymers with opposite chiralities being succesfully applied in stereocomplexation. Chapters 6 summarises the results obtained in Chapters 2, 3, 4 and 5 whilst Chapter 7 provides the experimental methodologies.

This project aimed to develop a high throughput, laser based, matrix-free, mass spectrometric technique using nanoporous and nanostructured semiconductor substrates for rapid, sensitive, high resolution and accurate mass analytical approach for complex biological matrices. Laser desorption/ionisation (LDI) based on nanostructured semiconductor surfaces is a novel matrix-free mass spectrometry approach. This novel LDI strategy is closely related to matrix-assisted laser desorption/ionisation (MALDI). However, the functions of the matrix are substituted by an active substrate and the mass spectrum does not suffer matrix interference at the low mass region (m/z below 700). This project aimed to develop this method for pharmaceutical and metabolomic applications, specifically metabolite profiling of complex biological matrices. It was the first time three rival technologies, DIOS, QuickMass and SALDI substrates were evaluated and compared under similar experimental conditions. The study included a comprehensive investigation of the physicochemical properties of these matrix-free LDI substrates, independently from the manufacturers or research group. It also included a comprehensive and detailed mechanistic study and demonstrated the suitability of this novel LDI approach in analysing complex biological mixtures consisting of a hundred or more small biomolecules. It is believed that the physicochemical properties of the substrate have a strong influence on the LDI efficiency. The nature of the substrates was determined by surface analysis and imaging techniques including secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Surface properties that govern the LDI processes were identified. It was found that though pores are not strictly required for ion generation, nano-sized porous structure is an important determinant affecting not only the ionisation efficiency, but also the detection mass range and the longevity of the signal. Although a roughened surface is required for the ion generation, the LDI performance does not depend strongly on the surface roughness, but perhaps more on the thickness, dimension, and density of the surface nanostructures. Micron-sized surface structures do not promote ionisation effectively. Both DIOS and SALDI were found to be silicon based, but the DIOS substrates had been fluoro-silanised. In contrast, the QuickMass substrates were found to be germanium based. The SALDI substrates were found to be oxides passivated. Investigation into surface cleaning technology and chemical modification was carried out on the SALDI substrates. Argon plasma etching followed by fluoro-silane modification was found to be suitable and enhanced the SALDI activity. It was found that fluorine and hydroxyl surface terminations are advantageous. It was proposed that the surface Si-OH moieties are an important proton source and fluorine increases the acidity of the Si-OH moieties. A wide range of biological and pharmaceutical compounds was analysed to determine the compound classes that were amenable to the method. Compounds analysed include amines, amides, amino acids, peptides, saccharides, steroids, lipids and small organic acids. The chemical properties of the compounds were correlated to the mass spectra generated. Laser induced surface reactions were also investigated by SIMS and XPS chemical imaging. It was found that the ionisation process is not a simple acid-base reaction, but a complicated simultaneous multi-reaction similar to that of MALDI. Laser induces further surface oxidation and produces a reduction potential. It was proposed that the energy transfer mechanism is closely linked to the excitation and relaxation dynamics of the exciton and the special surface state of surfaces' nanocrystallites. It was also proposed that the entropy of the reaction ultimately determines the ions observed and the rate of reaction determines the selectivity. This proposition departed from the conventional view of aqueous basicities and proton affinities dependence. The analytical characteristics of the DIOS target and MALDI Q-ToF mass spectrometer were investigated. A range of complex biological matrices was analysed, including blood plasma extract, liver extracts, urine extracts, bacterial cells and culture. Extraction methods and the application of principle component analysis (PCA) in the interpretation of the mass spectral data were explored. Suitable extraction methods were found to be important but generally, simplified approaches were sufficient. Even though the RSD value of the ion peaks intensity varied by 10-50%, the application of PCA to the DIOS spectral dataset was still possible.

Energy saving policies applied to modem buildings and air recirculation systems promote the build up of high levels of VOCs in indoor air. The growing concern related to the air quality in indoor environments requires the replacement of ineffective traditional purification methods, with an efficient and cost effective technology. Photocatalytic oxidation that utilise TiO2, represents a promising candidate for this purpose. However, the formulation of photocatalysts that can efficiently utilise a sustainable energy source (i.e. solar light), still represents an ambitious target in this field. In this study, different TiO2-based photocatalysts were synthesised by modified sol-gel and/or hydrothermal routes. The materials were characterised by XRD, SEM, N2 sorption (BET and BJH methods), UV-vis Spectroscopy and XPS. The photocatalytic activity of TiO2-based materials was systematically investigated at different light intensities, in a gas-phase flatplate photoreactor, using trichloroethylene (TCE) as model pollutant, and compared with that of the commercial product TiO2 Degussa P-25. This research provides insights into the influence of preparation parameters on different synthetical pathways for the preparation of highly active TiO2- based photocatalysts. The general approach to this investigation is based on the study of the influence of several processing parameters on morphological, textural and crystallographic properties of the photocatalysts, in order to correlate the material's features with their photocatalytic properties. The preparation of a wide range of pristine TiO2 allowed assessing a clear correlation between phase composition and crystal size and the photocatalytic performance. A series of highly active anatase photocatalysts was prepared. The best photocatalyst has an optimum crystal size of 28 nm and exhibits a photocatalytic activity that exceeds that of P-25 by a factor of over 2 times. A new TiO2/WO3 nanocomposites with peculiar crystallographic properties of the W component was developed by a novel one-step hydrothermal synthesis. The synthesis conditions were optimised with respect to the photocatalytic activity. Overall, the optimisation of the properties that enable an efficient interfacial charge transfer rate at the catalyst surface was found to be of fundamental importance for the design of improved TiO2-based photocatalysts.

The selective oxidations of the bioderived molecules, 1,2-propanediol, 1,3-propanediol and glycerol, were investigated using gold based catalysts. These reactions were carried out in both low pressure glass reactors and high pressure autoclaves. The reaction conditions such as temperature and amount of base were investigated to order to achieve the optimum conditions. The gold based catalysts used were prepared by sol immobilisation and impregnation methods. The supports tested were activated carbon, titania, ceria and magnesium oxide. The ceria supported catalyst was demonstrated to be extremely selective for the oxidation of 1,2-propanediol in methanol in which methyl lactate is the desired product. The addition of palladium to the gold catalyst led to an increase in activity for all supports, however, in the case of the ceria supported catalyst a decrease in selectivity was observed. The use of a magnesium oxide support was found to be advantageous in the oxidation of 1,3-propanediol and model compounds 1,4-propanediol and butyrolactone. An increase in activity and selectivity to the desired products, dimethyl malonate and dimethyl succinate, was demonstrated when this catalyst support was used. The structure of the support was found to be Mg(OH)2 when the catalyst was prepared by sol immobilisation. When prepared by impregnation methods the support retained its periclase MgO structure but was found to be far less selective than the Mg(OH)2 support.The use of this support for the oxidation of glycerol was investigated. When gold is alloyed with platinum on this support it is possible to achieve high conversions of glycerol and good selectivities to glyceric acid in base free conditions

Catalyzed oxidation of aromatic hydrocarbons with molecular oxygen has been studied for several decades. For example, toluene can be converted into oxidation products such as benzyl alcohol, benzaldehyde, benzoic acid and benzyl benzoate. At present, the principal industrial production of benzoic acid via the oxidation of toluene involves the use of homogeneous cobalt catalysts in an air pressurized aqueous acetic acid mixture in the presence of Mn ions. However, the use of solvent causes difficulties in the separation of catalysts and products, equipment corrosion, and due to the environmental hazards associated with the use of liquid acids as solvent. Developing solvent free toluene oxidation having great activity has attracted special attention as a promising environmentally friendly reaction. Recently, gold based supported catalyst have been found to be highly effective oxidation catalyst where a number of important discoveries have been made such as in hydrogen peroxide synthesis and selective oxidation of alcohols to aldehydes. As a proof of concept for the following studies, oxidation of toluene and other aromatic hydrocarbons were carried out in round bottom flask with TBHP as oxidant. At mild condition (80 ºC), it was evident that Au-Pd supported catalyst is capable of oxidising aromatics C-H bonds on toluene and derivatives and TBHP as oxidant also have been discovered well in this thesis. The catalyst preparation method was shown to be very important in the formation of active site catalysts. The sol-immobilisation catalyst with a narrow distribution of small particles, was more active than Au-Pd alloy having Au-core palladium shell with PdO dominance on the surface via impregnation catalyst. In addition to that, the choice of support is crucial and this study discovered carbon as a preferred support give enhance on performance activity of toluene. At the same time, the distribution of products can be altered with the choice of preparation methods and support. The synergistic effect of Au and Pd was confirmed by superior catalytic activity compared to monometallic catalyst. Investigations of reaction conditions such as reaction time, reusability, pre-treatment conditions, metal ratio, and mass of catalyst were fully investigated. It was found that the activity and selectivity of the catalyst was highly dependent on these variables. Reaction mechanism was proposed and it was based on catalytic evaluation data. Even though, the proposed mechanism was contradicted by the EPR data study, it was believed that the reactive oxygen species (ROS) was involved in the surface of catalyst and give effect of the catalytic activity. Overall, the oxidation of toluene was successfully studied by using Au-Pd supported catalyst and can not be denied that the importance of TBHP as oxidant involve in this process has been proven.

No description available.

The results have been interpreted in terms of the adsorption model

The conditions utilised in the purification of products resulting from the Mitsunobu reaction were also applied to the removal of ruthenium contaminants from metathesis products.This approach yielded splendid results.

This thesis examines the tolerance and effects of unnatural amino acid (Uaa) incorporation into proteins in Escherichia coli using an expanded genetic code. Uaa incorporation was used to alter or install new properties in the target proteins, superfolder Green Fluorescent Protein (sfGFP) and cytochrome b562. Chapter 3 deals with the technical aspects of Uaa incorporation including orthogonality of the machinery and yield. Substitution of residues in sfGFP for unnatural analogues of tyrosine was shown to be a valuable way of altering the properties of the protein. Variants were generated with red-shifted fluorescence and altered excitation spectra. The majority of this work focused on the Uaa, p-azido-L-phenylalanine (azPhe) as it has a number of properties that would be desirable for use in proteins such as photoreactivity and selective reactivity with alkynes. By incorporating azPhe into key residues of sfGFP, variants were created that could be controlled using light (Chapter 4). Light-dependant fluorescence activation, deactivation and switching were demonstrated in vitro and in live cells. The molecular basis for these changes was investigated by a combination of spectroscopy and X-ray crystallography in Chapter 5. The photoreactivity of azPhe was exploited for a different purpose in Chapter 6. Proteins were used as an alternative to synthetic cages for studying low temperature phenyl azide photochemistry. Here, two radicals (anilino and triplet phenyl nitrene) were successfully caged and detected on photolysis, with the radical observed dependant on the protein environment. Finally, in Chapter 7 the selective reactivity of azPhe was used to create proteins capable of site-specific modification (via Click chemistry). The position of azPhe on the protein surface was shown to have a significant effect on reaction yield and kinetics. Modification was used to install proteins with novel properties such as red-shifted fluorescence emission and the ability to bind to non-biological materials like graphene.