In der Arbeit werden Moeglichkeiten der Charakterisierung des Beschichtungsprozesses von C-Fasern mit pyro-Kohlenstoff vorgestellt. Dabei liegt der Schwerpunkt der Untersuchungen auf der ramanspektroskopischen Charakterisierung der Ober- flaechenstruktur von modifizierten Fasern. Die Unter- suchungen zeigen den Einfluss verschiedener Prozessparameter (Reaktortemperatur, Gasphasenkonzentration, Auswahl des jeweiligen Precursors etc.) auf die Oberflaechenstruktur der abgeschiedenen Schichten. Der Nachweis einer Vorzugsorientierung der Graphitmikro- kristallite auf der Faseroberflaeche wird mit verschiedenen Analysenmethoden durchgefuehrt. Dabei werden die ramanspektroskopischen Messergebnisse mit Ergebnissen anderer Methoden (wie Elektronenbeugung und Elektronenmikroskopie) verglichen. Waehrend des Beschichtungsprozesses wird die Gasphasen- zusammensetzung im Reaktor analysiert. Das Zersetzungs- verhalten von unterschiedlichen Precursoren bei verschiedenen Temperaturen wird untersucht. Korrelationen zwischen den einzelnen Precursoren aufgezeigt.

Organophosphate and phthalate esters are polymer additives that are frequently found in air and dust in indoor environments. This thesis describes the development and application of air sampling and selective mass spectrometric (MS) determination of these two compound groups. It also describes the sampling and screening of these compounds in indoor air and dust from different environments and the development and evaluation of a method for the extraction and determination of these compounds in indoor dust. An air sampling method previously used for air sampling of only organophosphate esters, is here demonstrated to be applicable for simultaneous sampling of both phthalate and organophosphate esters. Selective detection using tandem mass spectrometry (MS/MS) showed good results for simultaneous determination of organophosphate and phthalate esters in air. The high selectivity of this technique was especially advantageous when analyzing dust. Comparison of chemical profiles of the organophosphate ester between indoor environments including daycare centers, offices and private homes differed between the types of locations while the phthalate profiles were rather similar. Comparison of concentration levels of these compounds in multi-storey apartment buildings classified as either high or low risk “sick” buildings could not differentiate the two classes of buildings. Further, the studies also points out some potential sources of organophosphate and phthalate esters in these indoor environments. In general the levels of phthalate esters were consistently higher than the levels of organophosphate esters both in air and in dust. Phthalate and organophosphate esters were also determined in a dust standard reference material; seventeen of the targeted compounds were quantified out of which ten had not previously been reported for this reference material. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.</p>

Decorticated flax contains a significant amount of shive content, which limits applications of flax fibre. Separation of shives from the fibre is essential to improve the quality of flax fibre. Pneumatic method and a Sorter were implemented to meet the above objective. Terminal velocities of individual flax fibre and shive particles were investigated and their width, length, and mass were recorded. A sorting method was used for separation of short and long fibre for two grades of fibre: Grade 1 and Grade 2, with initial fibre purities of 51% and 15%, respectively. The ranges of terminal velocities for shive and fibre particles were 1.13 to 4.09 m/s and 0.51 to 1.07 m/s, respectively, which were significantly different. Fibre purity of approximately 80% for Grade 1 and 66% for Grade 2 were recorded from sorting, which were a significant improvement when compared to the initial purities. This study demonstrated the potential of the pneumatic and sorting methods for improving fibre quality. With the increase in resistant strains of microorganisms to antibiotics, researchers have started to explore plant parts to discover new antimicrobials. Since medieval times all portions of plants were used medicinally. Plant tissues, including stems, possess secondary metabolites (SMs), which have known antimicrobial properties. The purpose of this study was to investigate: the presence of antimicrobial compounds in stem extracts of canola, flax, hemp, and sweet clover; and study sorption-desorption behavior of their powdered stem material. GC-MS analysis of all extracts showed the presence of many SMs, including fatty acids, terpenoids, steroids, and sterols, etc. Many of the SMs found in the extracts have previously shown antimicrobial activity against a broad spectrum of organisms according to literature. Water sorption isotherms of stems showed a typical IUPAC Type II sigmoid curve similar to natural fibres. Equilibrium moisture content (EMC) of canola and sweet clover was significantly higher than flax and hemp at 95% RH, which were all higher than the fibre saturation point of wood (27%). The preliminary investigation via GC-MS showed promising results and water absorptivity results of stems can be used as the initial key property for many applications. / October 2015

Fast pyrolysis, the rapid thermal decomposition of organic material in the absence of oxygen, is a process that can be used to convert biomass into liquid fuels and chemicals. When performed at the micro-scale, pyrolysis is useful for characterizing biomass structure, as well as determining the pyrolysis products that can be generated from specific biomass feedstocks. Indeed, microscale pyrolysis coupled with on-line analysis of the pyrolysis vapors by GC/MS, so-called pyrolysis-GC/MS (Py-GC/MS), is a technique that can be used to characterize the structure and composition of the various components of lignocellulosic and microalgal biomass based on their pyrolysate distributions. Pyrolysates produced also provide insight into the range of products that can be expected when biomass feedstocks are subjected to thermal decomposition processes. This dissertation focuses on the Py-GC/MS analysis of lignocellulosic biomass such as sorghum and Scenedesmus sp. microalgae, in addition to high-lignin feedstocks such as walnut shells, coconut shells, olive pits and peach pits. The differences in the pyrolysate distributions among these biomass types are correlated with differences in the structure and composition of the biopolymers, mainly cellulose, hemicellulose and lignin, present in the biomass. Py-GC/MS analysis of lignin extracted from endocarp feedstocks is also emphasized. In addition to biomass and extracted lignin, sinapyl (S) and coniferyl (G) alcohol have been analyzed by Py-GC/MS in order to understand the relationship between the corresponding pyrolysates and sinapyl/coniferyl ratios of lignin present in lignocellulosic biomass.

The focus of this dissertation centers on the development and applications of gas chromatography/mass spectrometry and capillary electrophoresis methodologies to quantify monomeric compositions of the β-O-4 linkages in lignin. Pretreatment is a required step in the utilization of lignocellulosic biomass for biofuels. Lignin is the target of pretreatment because it hinders the accessibility of enzymes and chemicals to cellulose. The effects of pretreatment are commonly assessed utilizing enzymatic saccharification and lignin assays. However, these techniques do not elucidate the effects of pretreatment on the monomeric make up of lignin. The overarching hypothesis of this dissertation is that changes in individual monolignol content upon pretreatment can be observed from quantification. To test the hypothesis, a pretreatment, solution phase Fenton chemistry, was conducted on various lignocellulosic biomass feedstocks. Enzymatic saccharification studies showed a significant increase in glucose production upon Fenton pretreatment, however, lignin assays did not show a significant decrease in lignin content. Project two of this dissertation aimed to synthesize analytical standards in order to develop a quantitative thioacidolysis technique. The successful synthesis of the three arylglycerols were conducted utilizing and epoxidation reaction scheme which was hypothesized to produce a single diastereomer, as supported by GC/MS and chiral CE analysis. Upon method development, a quantitative thioacidolysis GC/MS method was applied to untreated and Fenton treated biomass. Results from this project revealed there was no significant change in the three lignin monomers. To verify the method, quantitative thioacidolysis GC/MS method was applied to a pretreatment method known to degrade lignin, alkaline peroxide pretreatment. The results of this project showed a significant change in monolignol concentrations upon alkaline peroxide pretreatment. Analytical degradative techniques, such as thioacidolysis, has traditionally assessed lignin as monomeric ratios. However, as this dissertation showed, upon alkaline peroxide pretreatment, no significant change was seen in the monomeric ratios, but there was a significant difference in all three monolignol concentrations. These results support the overall hypothesis that changes in individual monolignol content upon pretreatment can be observed from quantification. The works of this dissertation provides an analytical method which contributes to the elucidation of lignin.

Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2010.

Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2010.

Resin found within Canaanite amphorae from the Late Bronze Age shipwreck discovered off the coast of southwest Turkey at Uluburun has previously been identified as Pistacia sp. Although evidence from Egypt suggests that this resin was in high demand and typically transported in such amphorae, it has also been proposed that the amphorae contained wine, with the resin used to seal the interior surfaces and to flavour and/or preserve the wine. To attempt to resolve this question, we have analysed five samples of pistacia resin found in amphorae from the shipwreck using a range of analytical techniques which have used in the past for the analysis of wine residues: spot tests, FT-IR, and HPLC-MS-MS. As well as the archaeological samples, we have analysed modern samples of pistacia resin, leaves and fruit to determine the effectiveness of each technique and to exclude the possibility of false positive results. In addition to the analyses for wine we also detail analysis (GC-MS) of the terpenoids for the purpose of further molecular characterisation of the resin. Bulk stable isotope analysis was used in comparison with similar resins to attempt to identify the geographical origin of the resin.

Flocculation, the process whereby yeast cells attach in groups and sediment to the top or bottom of a fermenter, is industrially important in many fermentation batch operations. These batch operations include wine, distilled spirits, cider, bio-ethanol and production of commercial yeast metabolites. In the case of brewing yeast, it has been determined that flocculation occurs due to three forces called hydrophobic interactions, zymolectin binding and to a lesser extent, surface charge neutralization. This project sought to more closely study hydrophobic interactions and zymolectin binding. Earlier studies had shown that certain hydrophobic carboxylic acids, 3-OH oxylipins, formed in brewing yeast at flocculation onset. Therefore, these compounds showed potential as an indicator of overall cell surface hydrophobicity, and it was believed that flocculation level, cell surface hydrophobicity and oxylipin level would increase in unison in the yeast cell during brewing fermentations. During lab scale fermentations in shaker flasks and in a miniature fermentation assay setup, both flocculation level and cell surface hydrophobicity increased coincidently. However, 3-OH oxylipins could not be isolated from whole cells or cell wall isolates grown in the shaker flasks or whole cells grown in the miniature fermentation assay at detection limits approximated as 50 ng/0.5 g wet yeast. Due to their minute levels in brewing yeast cells, it was proposed that 3-OH oxylipins may mediate flocculation and aggregation via a quorum sensing mechanism instead of by increasing cell surface hydrophobicity. A disagreement exists in the literature where certain researchers believe zymolectin activity is induced, while others believe it is constitutive. The second part of this study attempted to address this by measuring zymolectin density during lab scale fermentations with a flow cytometer. Because of flow cytometry’s capacity for multiparametric analysis, large amounts of data were produced which gave information on not only zymolectin density, but also cell size and cellular complexity. Upon statistical analysis of the data, it was not possible to either refute or confirm the claim that zymolectin activity is induced or constitutive. However, the results suggested there could have been a population of cells with fewer zymolectins, and this certainly warrants further investigation. During the lab scale fermentations, cell size measured by a flow cytometer appeared to be correlated with manual measures of cell size. Furthermore, cell size tended towards uniformity during the fermentation which has also been observed in similar studies employing flow cytometry. Conversely, the cellular complexity of the yeast in this study did not change as in other studies by this may have been due either to strain differences or the methods used herein.

Univ., Diss.--Würzburg, 1995.