This study used Raman spectral analysis to characterise the structural order of carbon in three carbonaceous chondrites and twelve achondrites. The achondrites analysed were a group of carbon-rich meteorites, known as ureilites. These meteorites are composed primarily of olivine and pyroxene and have igneous textures but contain noble gases and primitive oxygen isotopes which appear to contradict their high temperature origin, which has led to the group being described as “enigmatic” by some authors. This study used Raman spectral analysis to show that ureilite carbon is heterogeneous, even at the micrometer scale, and is derived from more than one source. In order to better understand the processes involved in ureilite formation, terrestrial analogues containing carbonaceous material with similar spectral characteristics to the meteorites were identified. Analysis of terrestrial samples showed that the sedimentary carbon can be incorporated into igneous rocks with little structural change, suggesting that the same may be true for carbonaceous material in ureilites. Although the terrestrial carbon is biogenic in origin, it is structurally similar to pre-biotic organic matter found in meteorites. Carbon can be used as an effective tracer for geological events, such as melting and heating, which appear to be ubiquitous in planetary evolution. This study concluded that carbon is a primary component of melts on the ureilite parent body (UPB) and that impact processes have increased the heterogeneity of ureilite carbonaceous material. Carbon is likely to have been remobilised by later impact events, explaining the lack of correlation between carbon content and isotopic values with other geochemical parameters. Spectral analysis suggested that most of the carbon in ureilites is derived from primitive material.

Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 1997. / The purpose of this investigation was to analyse and compare the Nuclear Magnetic Resonance (NMR) spectra of samples of quinquagenimillesimal (LM) potencies of homoeopathic Sulphur and a lactose-based control produced according to Hahnemann, in order to evaluate homoeopathic medicines thus prepared. It was hypothesised that differences existed in the spectra of respective Sulphur samples, control samples, and between parallel samples of Sulphur and control. It was further hypothesised that these differences correlated proportionately with the degree of potency of samples. The design of the investigation was that of a scientific experiment. Potencies of Sulphur and a lactose-based control were prepared (according to the directions of Hahnemann*) to the LM10 level. LM2, LM6 and LM10 liquid potencies (95% ethanol) of each group were then prepared in =20.8160 ml volumes and despatched for sampling and measurement. NMR spectroscopy was conducted on fifteen (15) samples of each potency. These were prepared in coaxial sample tubes using deuterium oxide (020) as an extemal lock and dioxane as a reference. Samples were drawn and measured in overlapping sequence by the Department of Chemistry, University of Cape Town. The spectrometer em. ployed was a. Varian VXR200 operating at a frequency of 200.057 MHz. Acquisition time for each sample was 3.727 seconds, using a pulse width of 6\xB0. Measurement of each sample was repeated eight times, at a constant temperature of 298.1 K (250. OC) / M

Unsustainable energy sources are running out and global warming is getting worse. Therefore the need for renewable energy sources is growing. Solar cells are a popular options used as an energy source. Most popular are the inorganic photovoltaic cells. With their high efficiency and long lifetime, they make a very good energy source. Unfortunately the costs for inorganic solar cells are rather high. Organic solar cells can make a good replacement for inorganic photovoltaic. They are easy to make, light and rather cheap. In this thesis, the morphology of a model system of the active layer of organic solar cells will be discussed, using dip coating as well as spin coating as a technique to prepare the films. The films consist of a blend of poly(9,9-dioctylfluorenyl-2,7-diyl) and [6,6]-phenyl C61-butyric acid methyl ester in different ratios and different solvents. The films that were made were prepared by spin coating or dip coating a glass substrate. After analysing the samples using atomic force microscopy, fluorescence spectroscopy and absorption spectroscopy it was clear that the morphology, as well as the position of the polymer chains can be influenced by using different dipping speeds, ratios or solvents.

Gases at satisfactory pressures fluoresce in the presence of radio frequency radiation (6). Such fluorescent gases have been used to probe fields of radio frequency oscillation and their emission spectra have been recorded and studied. Ions with multiple charges also exist in these gases, (6). In 1941 Oliver (12) observed the fluorescence of an isobutane- isobutene gaseous mix flowing to a pump through a glass tube which was wrapped by a spiral antenna of a sevenmegacycle transmitter. A white deposit was noticed at a bend in the tubing on the pump side of the fluorescing section of the gas (12, p. 8). In 1957 Blacknall (3) studied the fluorescence and reaction products of propylene in the antenna region of sevenmega- cycle radiation, The oscillator employed by Blacknall was an ARC-5/T-22 military surplus transmitter of range 7.00 to 9.10 megacycles, which he operated at 7.00 megacycles. Blacknall observed a drop in pressure and the formation of a brown deposit in the region of the coil. Blacknall did not report an analysis of this product. In 1959 Armstrong (1) repeated Blacknall's experiments and modified Blacknall's apparatus into an improved design. He also performed an analysis on Blacknall's product. Blacknall used a vertical open-end mercurial manometer with which to measure pressure in his system and as a result introduced mercury vapor into his system. Armstrong tried to minimize the amount of mercury introduced by covering his manometric mercury with a layer of octyl sebacate, "octoil". Armstrong used a spiral-would antenna wrapped around his reaction vessel and reported the formation of spiral brown rings coincident with the copper wire of the antenna. There was a white product deposited in a spiral interlaced with the spiral of dark brown material. No definite identification was reported by Armstrong other than reporting, his solid material as isotactic polypropylene. Other work on electrodeless discharge of organic chemicals has been done in 1960 by Durward Smith and William Smith (13), in 1961 by Jimmie McCarty (10), and in 1963-64 by David Flinn (4).

This thesis concerns the study of equilibrium and photo excited carriers in thin-film semiconductors using terahertz time-domain spectroscopy (THz- TDS) and optical- pump terahertz-probe (OPTP) spectroscopy. In particular, it focuses on the develop- ment and application of a MATLAB program to extract the sample complex refractive index (and thereby the complex conductivity) from THz-TDS data. The parameter extraction procedure was developed to be effective in the case of thin-film samples for which the transmission function contains a substantial contribution from multiple internal reflections in the sample. The program's effectiveness was demonstrated in the case of a 30 nm-thick film of gold deposited on silicon; the program successfully extracted the complex refractive index while the original method failed. The program was applied in a study of thin-film nanoporous indium phosphide (InP). The frequency-dependent complex conductivity-obtained via THz- TDS meas- urements-was not Drude-like, as observed for bulk InP, but was qualitatively con- sistent with a plasmonic response. The time-resolved photoconductivity was obtained from OPTP spectroscopy measurements, and revealed that the presence of pores substantially increases the photo carrier lifetime compared with the value measured for bulk InP. This behaviour is attributed to the presence of surface-bound electronic states that pin the Fermi level at the pore surface, bending the electronic bands upwards. This creates a depletion region which contains the carriers away from the recombination sites at the surface. The significance of the role played by surface states in determining carrier be- haviour is further evidenced by a study of carrier dynamics in etched and surface- passivated semi-insulating gallium arsenide (SI-GaAs). Compared with an untreated sample, surface-passivated SI-GaAs exhibited a greater change in photoconductiv- ity upon generation of photocarriers and an increased photo carrier lifetime. These observations are attributed to an increased photo carrier mobility and a decreased recombination rate resulting from the removal of surface states.

Doctor of Philosophy / Department of Biological and Agricultural Engineering / Wenqiao Yuan / Biodiesel production and utilization has been increasing rapidly worldwide in recent years. A main challenge in the commercialization and public acceptance of biodiesel is its quality control. This work reports the use of infrared spectroscopy to monitor biodiesel quality through the development of models to predict (1) the blending level of biodiesel in biodiesel-diesel mixtures, (2) the fatty acid profile of biodiesel fuels derived from various lipids, and (3) the concentration of most common impurities present in biodiesel including water, glycerol, methanol and triglycerides. Regressions based on near-infrared (NIR) spectroscopy were developed for relatively inexpensive and rapid on-line measurement of the concentration and specific gravity of biodiesel-diesel blends. Methyl esters of five different oils—soybean oil, canola oil, palm oil, waste cooking oil, and coconut oil—and two different brands of commercial-grade No. 2 on-highway diesel and one brand of off-road No. 2 diesel were used in the calibration and validation processes. The predicted concentration and specific gravity of the biodiesel-diesel blends were compared with the actual values. The maximum and average root-mean-square errors of prediction (RMSEP) of biodiesel concentration were 5.2% and 2.9%, respectively, from the biodiesel type-specific regression. For the general regression, the RMSEP were 3.2% and 0.002 for biodiesel concentration and specific gravity predictions, respectively. Five different models were developed to determine the concentration of methyl palmitate (C16:0), methyl stearate (C18:0), methyl oleate (C18:1), methyl linoleate (C18:2), and methyl linolenate (18:3) present in biodiesel. Using the NIR range a set of models based on four different types of biodiesel was developed. The maximum RMSEP was 0.553% when the models were validated with biodiesel samples that were used in the calibration, however, prediction accuracy of the model under external samples was poor, therefore, a new set of models was proposed. For this case, six different types of biodiesel were used. The models developed for C18:1, C18:2 and C18:3 presented good accuracy on prediction. However, for C16:0 and C18:0, additional work was necessary to reach reasonable accuracy in prediction. Three sub models for specific ranges of concentration (low, medium, and high) were developed. The RMSEP was reduced from 2.98% to 1.51% for the C16:0 and from 2.33% to 0.56% for C18:0, when the sub-models were validated under internal and external samples. Similar procedures were followed to develop regression models based on mid infrared (MIR) spectra. The RMSEP for C16:0, C18:0, C18:1, C18:2, and C18:3 were 0.83%, 0.37%, 1.45%, 1.59%, and 0.84%, respectively. Predictions using MIR spectroscopy models were better than those obtained with NIR spectroscopy models for the C16:0 and C18:0 models. The most common impurities present in biodiesel from production processes, including methanol, free glycerol, triglycerides, and water, were determined by infrared methods using NIR and MIR spectra and partial least square regression (PLSR) methods. The models were developed in two different approaches, one was when a single impurity was present and the other was when all impurities were present. In the single impurity models, the maximum RMSEP obtained in the NIR and MIR models were 647 mg kg[superscript]-1 and 206 mg kg[superscript]-1, respectively. The models for methanol, glycerol, and water performed better using the NIR data. For the triglycerides model, MIR worked better. Only NIR data were used to develop the models for samples with all impurities. Data pre-treatment (Savitzky-Golay second derivative) was necessary to achieve reasonable accuracy in the predictions in this type of models. The maximum RMSEP was 932 mg kg[superscript]-1 presented in the model for triglycerides. The best performance was obtained in the model developed to predict methanol concentration in biodiesel with RMSEP of 177 mg kg[superscript]-1 when all listed impurities were presented. The feasibility of using NIR and MIR spectroscopy to monitor biodiesel quality was demonstrated in this work. The developed method was accurate, rapid, convenient, yet inexpensive to determine some important characteristics of biodiesel, such as biodiesel blending level in biodiesel-diesel mixtures, the fatty acid profile of biodiesel, and impurities present in the fuel.

Call number: LD2668 .T4 1957 K63 / Master of Science

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. May 2016. / Tungsten carbide cobalt (WC-Co) cemented carbides are widely used for cutting, drilling, machining and as wear resistant materials due to the combination of high hardness and fracture toughness. In this work, we report on as-milled and as-sintered WC-10Co-20Fe samples which were ball milled for 15 hrs and sintered using liquid phase sintering (LPS). These samples were investigated by Vickers hardness test, microstructural analysis, X-ray diffraction (XRD), transmission Mössbauer spectroscopy (TMS) and conversion electron Mössbauer spectroscopy (CEMS) techniques. A mean hardness value of 1160 ± 42 HV was obtained for WC-10Co sample while a value of 776 ± 35 HV was determined for the WC-10Co-20Fe using the Vickers hardness tester. The lower hardness value for WC-10Co-20Fe is attributed to the high volume of the binders (10% Co and 20 %Fe) incorporated in the sample. The microstructural analysis of the as-sintered WC-10Co and WC-10Co-20Fe samples reveals that the light regions represent the WC phases and the dark regions signify the presence of the Co and CoFe phases in the as-sintered WC-10Co and WC-10Co-20Fe samples, respectively. The energy dispersive spectroscopy (EDS) of the as-sintered samples shows the presence of the starting powders used (WC, Co and Fe) and some Cr contamination resulting from either the production process or the starting powders. / GR 2016

The main task of this thesis is to find the ICT activator of a carotenoid spheroidenone in the pigment-protein complex LH1 of Rhodobacter sphaeroides. The ICT state is characterized by a red-shifted positive transient absorption signal around 750 - 800 nm. We hypothesize that the presence of the ICT state is associated with the pigment-protein interaction of a carotenoid keto group and specific amino acid in the protein. To perform the experiment, four mutant complexes with amino acids substitutions, which should result in decreased intensity of the ICT signal due to a weaker or missing pigment-protein interaction, were obtained and measured using femtosecond time resolved pump-probe spectroscopy.

Cheung Ching Ying. / Bibliography: leaf 126 / Thesis (M.Phil.)--Chinese University of Hong Kong