The deposition of atmospheric nitrogen is now recognized as a major driver of biodiversity changes at mid to high latitudes. It has previously been shown that regional variations in wet nitrogen deposition in the British Isles are reflected in broad targeted chemical parameters in the common heathland lichen Cladonia portentosa. A more detail analysis of alterations in the metabolic pathways in Cladonia portentosa collected from different locations within the UK was undertaken by applying the environmental metabolomics approach. Fourier transform infrared spectroscopy (FTIR) and liquid chromatography mass spectrometry (LC-MS) were applied in combination with principal component analysis (PCA) and partial least squares regression analysis (PLSR). The latter statistical method was used to correlate measured variables with modelled atmospheric data including wet nitrogen deposition, nitrogen concentration and precipitation. While FTIR in combination with PCA and PLSR revealed signatures of broad metabolic classes, LC-MS in combination with PCA and PLSR allowed the identification of betaine lipids (BL) as potential biomarkers of nitrogen enrichment. A compound tentatively identified as monoacylglycerol-(N,N,N trimethyl)-homoserine (MGTS) showed the strongest positive relation to increasing wet nitrogen deposition regimes and consequent phosphorus deficiency. In contrast, the structurally related phosphatidylcholine containing a C18:2 ester showed the opposite trend in natural populations of C. portentosa. Results obtained for C. portentosa collected from the N manipulation site Whim Moss indicated that ammonium is causal for the increase of two of the identified betaine lipids in natural populations in C. portentosa. Betaine lipids as well as the phosphatidylcholine biomarker could potentially be used to monitor nitrogen regimes and resulting phosphorus limitation on the lichen C. portentosa. The approach used for this study represented an effective integration of the complementary analytical techniques of FTIR and LC-MS in combination with multivariate statistical tools for environmental metabolomic studies.

The deposition of WOx and FeOx thin films by reactive PLD and post-deposition annealing in an oxygen environment have been investigated. The influence of the deposition parameters on the growth and structure of WOx as well as the electronic and structural properties of FeOx thin films are presented. WOx thin films have been deposited onto native oxide Si (100) and SrTiO3 (100) substrates, whilst FeOx films were deposited onto glass and MgO (100). The films have been analysed using X-ray diffraction (XRD), texture pole figure analysis, X-ray reflectivity (XRR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and resistance vs temperature measurements. The WOx films deposited on both Si and SrTiO3 substrates were found to exhibit a dependence on the primary texture with fluence in the range of 5.3 J cm-2 to 14.7 J cm-2. The WOx films deposited on SrTiO3 were observed to exhibit a biaxial texture whilst the films on Si displayed a (002) WO3 out of plane fibre texture. The primary texture of the WOx films on SrTiO3 was observed to evolve from (200)/(020) WO3 to a single (002) WO3 texture with increasing fluence. The FeOx films deposited via reactive PLD onto glass substrates were found to exist in the Fe2O3 oxidation state for all parameters used. The production of Fe3O4 by post-deposition annealing of Fe films on glass and MgO (100) substrates in an oxygen environment is also presented. On both substrates it was necessary to use a two-stage anneal process to produce Fe3O4; an initial 175 °C oxygen anneal followed by a 500 °C vacuum anneal. The presence of Fe3O4 was confirmed by the existence of the Verwey transition at close to 120 K, during resistance vs temperature scans. The anneal parameters required to produce Fe3O4 are shown to be different for MgO substrates in comparison to glass.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / The feasibility of extracting iron from iron(III) oxide bearing materials with acetylacetone has been under investigation for many years. This is an alternate, environmentally friendly process for the recovery of iron compared to conventional processes that are energy intensive, have numerous costly process steps and produce large quantities of greenhouse gases. Iron(III) oxide bearing waste materials can be used in this process which reduces its environmental impact as it would not require waste storage. This study investigated the feasibility of reducing the reaction time of the liquid phase extraction of iron from iron ore fines by performing the extraction at elevated pressures and temperatures. It was found that that the extraction under pressure was dependent on temperature, pressure, particle size and solid to liquid ratio. It was found that at high temperatures and long extraction times, an unknown secondary reaction occurs that consumes the desired product, iron(III) acetylacetonate, and inhibits the recovery of these crystals. This results in lower extraction yields. It was found that the side reaction was largely dependent on the temperature of the system and the amount of iron(III) acetylacetonate present. The effects of the side reaction could be limited by lower operating temperatures and reducing the total reaction times. An optimum conversion of iron(III) oxide to iron(III) acetylacetonate of 47.2% was achieved for synthetic iron (III) oxide (> 95 wt% Fe2O3) at a total extraction time of 4 h, 160 °C, 0.025 g:1 mL, operating pressure of 1700 kPa, initial N2 feed pressure of 1010 kPa and 375 rpm stirrer speed. The optimum extraction of iron from iron ore fines (> 93 wt% Fe2O3) to iron(III) acetylacetonate was found to be 20.7% at 4 h, 180 °C, 0.025 g:1 mL and operating pressure of 1900 kPa, initial N2 feed pressure of 1010 kPa and 375 rpm stirrer speed. These are the optimum conditions where the side reaction is limited to improve the recovery and desired reaction conversion capabilities of the process. The operation under pressure yielded lower conversions than that of the atmospheric leaching process developed by Tshofu (acetylacetone water system under reflux). It was also found that it was not possible to reduce the extraction time and achieve comparable extractions when operating at higher temperatures and pressures. The formation of an additional unwanted product would also lead to unnecessary treatment costs in an industrial process. Hence, it was found that pressure leaching as an alternative is not currently viable due to the lower yields and associated high costs. Atmospheric leaching seems to be the most economically feasible option until a better alternative is found. / MT2017

A Dissertation submitted to the Faculty of Science, School of Chemistry, University of Witwatersrand in fulfillment of the requirements for the degree of Master of Science. Johannesburg 2014 / The resin-gel method of synthesis successfully produced compounds of mixed metal oxides of copper titanium oxide powders of the form CuxTiyOZ with different compositions. These include Cu3TiO5, Cu3TiO4, Ti3Cu3O, Cu2Ti4O, Cu2Ti2O5 and Cu2TiO3. Heat-treatment of the powders at 300°C, 500°C, 700°C and 900°C for 1 hour was performed to determine the full composition/temperature phase diagram. The target particle size was in the 10- nanometer range, and for most of the samples, this size was achieved. Powder xray diffraction and transmission electron microscopy were the main techniques used to study the crystallization of these materials and their transformation to other polymorphic phases under different temperatures. Phase-match, particle size analysis and TEM imaging determined the properties and characteristics of the respective crystallographic phases of these materials. TEM analysis showed that some powders agglomerated while others exhibited both regular and irregular morphologies and polydisperse particle size distribution. Only a single unique phase was identified, but its structure could not be determined.

No description available.

Metal oxide materials could offer earth-abundant, non-toxic alternatives to existing lightabsorber materials in thin-film photovoltaic and photoelectrochemical cells. However, efficiency of these devices based on existing metal oxides is typically low due to poor material properties. In this research, novel Sb:SnO2 nanorod and nanotube electron collectors have been synthesized, investigated and were used to improve the photo-conversion efficiency of top-performing BiVO4 photoelectrochemical cell. The performance of Sb:SnO2/BiVO4 photoanode achieved a new record for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ~ 57.3% and 58.5% under front- and back-side illumination at 0.6 VRHE and Sb:SnO2/BiVO4 PV cell achieved 1.22% solar power conversion efficiency. In addition, a new promising metal oxide material (CuBiW2O8) has been synthesized and its optoelectronic properties have been investigated to make photovoltaic cell which has potential to achieve over 30% solar power conversion efficiency.

Ling Siu-hing. / Title also in Chinese characters. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 220-227). / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / Chapter Chapter 1 --- Ceramic thin film --- p.1 / Chapter 1. 1 --- """New stone era""---the importance of ceramics" --- p.1 / Chapter 1.2 --- The importance of epitaxial growth of YBCO films --- p.4 / Chapter 1.3 --- The importance of epitaxial growth of PZT films --- p.9 / Chapter 1.4 --- The similar structures of YBCO and PZT --- p.10 / Chapter Chapter 2 --- Epitaxy --- p.12 / Chapter 2. 1 --- Introduction --- p.12 / Chapter 2.2 --- Basic principle --- p.13 / Chapter Chapter 3 --- Sample preparation Techniques --- p.25 / Chapter 3.1 --- A glimpse at epitaxial film deposition --- p.25 / Chapter 3.2 --- Magnetron sputtering --- p.28 / Chapter 3.2.1 --- Principle --- p.28 / Chapter 3.2.2 --- Set-ups --- p.30 / Chapter 3.2.3 --- High pressure magnetron sputter gun --- p.33 / Chapter 3.2.4 --- Type II unbalanced magnetron gun modification --- p.42 / Chapter 3.3 --- Pulsed Laser Deposition (PLD) --- p.54 / Chapter 3.4 --- Rapid thermal annealing (RTA) --- p.62 / Chapter Chapter 4 --- Characterizations-principles and setups --- p.66 / Chapter 4.1 --- Structure-X-ray diffractometer --- p.66 / Chapter 4.1.1 --- Setup --- p.57 / Chapter 4.1.2 --- Characterization --- p.71 / Chapter 4.1.3 --- High temperature X-ray diffractometer (HTXRD) --- p.83 / Chapter 4.2 --- Surface morphology --- p.86 / Chapter 4.2.1 --- Scanning electron microscopy (SEM) --- p.86 / Chapter 4. 3 --- Composition --- p.89 / Chapter 4.3.1 --- Energy dispersive X-ray spectroscopy --- p.89 / Chapter 4.3.2 --- Rutherford backscattering spectrometry (RBS) --- p.91 / Chapter 4.4 --- Other characterization techniques --- p.93 / Chapter 4.4.1 --- Thickness measurement --- p.93 / Chapter 4.4.2 --- Measurement of Tc in YBCO --- p.93 / Chapter 4.4.3 --- Thermomechanical analysis system (TMS) --- p.95 / Chapter 4.4.4 --- Differential scanning calorimeter (DSC) --- p.98 / Chapter Chapter 5 --- Epitaxial films --- p.99 / Chapter 5. 1 --- YBCO films --- p.99 / Chapter 5.1.1 --- YBCO on sapphire --- p.99 / Chapter 5.1.2 --- YBCO on spinel (MgAl2O4) --- p.115 / Chapter 5.1.3 --- YBC0//SrTi〇3//spinel --- p.130 / Chapter 5.1.4. --- YBCO on Mg〇 --- p.134 / Chapter 5.1.5 --- YBCO on SrTi〇3(110) --- p.143 / Chapter 5.2 --- PZT films --- p.182 / Chapter 5.2.1 --- PZT on MgO --- p.182 / Chapter 5.2.2 --- PZT on spinel --- p.188 / Chapter 5.2.3 --- High temperature structural transition of PZT films --- p.195 / Chapter Chapter 6 --- Conclusion --- p.218 / REFERENCES --- p.220

No description available.

Wong Wai Fun. / "June 2006." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 226-230). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

The materials synthesised in this study were designed to have novel morphology coupled with a tightly controlled surface composition that could be varied depending on a application. Preparations with simple single metal oxides (i.e. TiO2, SiO2, Al2O3 and ZrO2) were used as the starting point with the latter stages involving multi-metal oxide coatings and materials. The research was divided into three interconnected areas; i) biotemplating, ii) alternative synthetic morphologies to biotemplating and iii) the synergy between microparticles and insecticides. For the investigation into biotemplating pollen was chosen as the main example due to its ubiquity. Here, good replication of its structure with metal oxides can be achieved by two-dimensional solgel chemistry. Such materials can be further modified to have tunable surface chemistry through dopants and optical properties (i.e. fluorescence) through the use of dyes. Materials were extensively characterised using primarily spectroscopy (UV and IR) and microscopy (i.e. SEM coupled with EDX elemental analysis). These were considered for several applications and examples investigated here included as a taggant technology and photocatalytic removal of methyl orange in an aqueous environment (TiO2-pollen only). For the latter, results have been compared with those of a commercially available alternative (P25) where the preliminary results are very promising. The method of overcoating was also shown to be transferrable to other flora and fauna biotemplates. Synthetic alternatives for the biotemplated pollen were considered in the second investigative area where solution sol-gel processes such as the Stöber method were considered in addition to other suspension based precipitation methods (i.e. refluxes and microemulsions). Processes developed in the biotemplating research were applied here and analysed again using spectroscopy and microscopy as the main techniques. As part of this aspect, a novel fast-drying water-in-oil microemulsion delivery and preparative system was also developed using low boiling point solvents such as isopentane and ethanol and low toxicity sucrose ester surfactants. Hollow oxide shells could be prepared in these using a novel low-temperature route that were comparable in thickness (but significantly smaller in size) to hollow pollen replicas. In this second area attention was shifted to more focus on oxides of Si and Al (as opposed to TiO2 that used extensively in biotemplating) to broaden the scope of the research and investigate other potential applications, such as nanoabrasives (surface roughness and ability to cleave DNA). The third and final area of interest used the materials from the previous two aspects in coatings that were applied to investigating the knockdown (KD) and total mortality (TM) of selected arthropods. Here mosquitoes of the A. Gambiae and S. Aegypti genus were considered with particular focus on synergistic effects with existing commercial insecticides (using mainly CDC bottle tests). Microscopy was used as the primary characterisation technique here to determine particle transfer after each assay. In these tests %TM suggested SiO2 microspheres were particularly effective at in enhancing mortality of the commercial l-cyhalothrin insecticide. Additionally, novel methods of recording mosquito behaviour was investigated through optical and thermographic stills and videos.