Thesis (M.D.S.)--University of Hong Kong, 2004. / Also available in print.

>Magister Scientiae - MSc / The negative environmental impact of fossil fuels and growing concerns about petroleum supplies has driven the search for alternative, renewable transportation fuels. An 'ideal' fuel replacement would be a biofuel produced from lignocellulosic biomass. Unfortunately, the presence of lignin in plant cell walls impedes the breakdown of cell wall polysaccharides into simple sugars and the subsequent conversion of these sugars into useable fuels. One of the most common fates of lignin in nature is to be metabolized by lignin peroxidases (LiPs), predominantly of microbial origin. This study aims to isolate and characterise microorganism(s) involved in the degradation of lignocellulose. Thermophilic bacteria were isolated from straw-based compost and screened for lignin peroxidase activity. One isolate, CP11, showed significant lignin peroxidase activity and based on 16S rRNA gene sequence analysis, the isolate was found to be most closely related to Bacillus thermoamylovorans. Morphological, physiological and biochemical characterisation was conducted to determine whether the isolate was a novel species. Morphologically, CP11 was characterised as an endospore-forming, Gram positive rod. In addition, the isolate was found to be a facultative anaerobe, catalase positive and capable of utilising a range of carbon sources including glucose, sucrose and arabinose. Isolate CP11 was moderately thermotolerant and grew between 37°C and 55°C, with an optimum growth temperature of 45°C. Based on its phenotypic characteristics CP11 could be clearly distinguished from its closest phylogenetic neighbours. Preliminary characterisation of the lignin peroxidase was conducted using crude enzyme extract and Azure B dye as the substrate. Activity was detected in the supernatant only and a growth curve was constructed to determine the growth phase of lignin peroxidase production. In order to identify the gene encoding the lignin peroxidase a small insert library was constructed and screened for ligninase activity using Azure B as the substrate. / National Research Foundation

Introduction: One factor that contributes greatly to the lower face appearance and orthodontists have the ability to affect is lip profile. Clinical assessment of the lip profile is an important element in the decision of orthodontic treatment planning and in the evaluation of treatment progress and outcome. Three known factors influence the lip profile; the lip thickness, the underlying bone, and the tooth position. The positions and inclinations of the anterior teeth can affect the lip position, but it is unclear whether orthodontic brackets bonded to the labial surface of anterior teeth move the lip position and thereafter change the lip profile. Therefore, it is necessary to determine if orthodontic brackets bonded to the labial surface of the anterior dentition have any impact on lip profile. Objective: The objective of this project was to determine the effect that bonded brackets have on lip profile utilizing a standardized lateral photographic cephalogram analysis during the bonding and debonding stages. Methods: To determine the effect of bonded brackets on lip profile, digital photographic cephalometry was used. The patient was seated against a white backdrop in the standardized natural head position. Photographs were taken 5 feet from the patient, centered and level with the middle of the tragus of the right ear and were digitally analyzed using Dolphin Imaging software. Photos were acquired from 4 time points: before bonding (BT0) and after bonding (BT1) for the bonding group, and before debonding (DT0) and after debonding (DT1) for the debonding group. Upper and lower lip to E-plane, subnasale and lower lip to H-Line, superior sulcus depth, nasolabial angle, Z angle, upper and lower lip protrusion, and upper and lower lip to S-line were measured and analyzed statistically. The correlation of tooth angulation, lip thickness (determined using existing cephalometric radiographs), and bracket thickness on effect of lip position was also determined. Results: There are significant differences in all measurements of the lip profile, except superior sulcus depth and nasolabial angle, between BT0 and BT1 at the bonding stage. In the bonding stage, change in Z angle was correlated to initial lower lip thickness and change in upper lip protrusion was correlated to the initial upper lip thickness at the vermilion boarder and upper incisor bracket thickness. There was no significant difference noted between DT0 and DT1 at the debonding stage. Conclusion: Brackets have a significant effect on lip profile when bonding labial orthodontic brackets. Brackets have no significant effect on lip profile when debonding brackets. Therefore, a direct clinical assessment of lip profile before debonding is valid with no interference imposed by bonded orthodontic brackets.

Large Igneous Provinces (LIPs) form during short-lived pulses of extensive magmatic activity. LIPs are known for their ability to affect global climate as well as for their Ni-Cu-PGE ore potential. A key factor that controls the intensity of the climate impact of a LIP and its ore potential is the assimilation of volatile-rich sedimentary host rocks. Magmas of the High Arctic Large Igneous Province (HALIP), exposed in the Arctic, intruded volatile-rich black shales, carbonates and evaporites in the Canadian Arctic Islands, offering a great opportunity for studying magma-sediment interaction. The purpose of this study is to test whether assimilation of sedimentary sulphide can promote sulphide immiscibility in magma and thus aid formation of Ni-Cu-PGE ore bodies. This is done by analysing sulphur isotopes in pyrite grains hosted in a HALIP dolerite sill, which was emplaced into black shale, by using Secondary Ion Mass Spectrometry (SIMS). Four dolerite samples are analysed; two coming from the lower contact margin of the sill, one from 60 cm into the sill and one sample from a basaltic vein at the upper contact margin of the sill. A total of 14 pyrite grains (n = 246 individual SIMS spot analyses) were analysed for their sulphur isotope ratios. The results of the SIMS analyses show that all analysed sulphides have highly negative δ34S values ranging from -19.5 to -5.7‰ (average δ34S = -8.2 ± 0.83‰, 2SD), which therefore differ largely from that of the primitive mantle (0 ± 1.8‰). In order to put our four analysed dolerite samples into a broader context, δ34S data of our sulphides are compared with whole-rock δ34S and δ18O data from Hare Fiord shale and dolerite samples. The δ34S values of the sulphide samples from the sill typically trend toward the negative sulphur isotope composition of the sulphides in the surrounding shale, and the shale surrounding the sill experiences a loss of 32S near the contact of the sill. This indicates that sedimentary light sulphur (32S) has been locally incorporated into the sill by the surrounding shale, resulting in negative δ34S values in the magmatic sulphides. Since sulphide immiscibility in the Hare Fiord sill was triggered by assimilation of sulphur from host rock shale, the igneous rocks of the HALIP may be prospective for Ni-Cu-PGE mineralization, though more studies are needed. Furthermore, our results suggest that incorporation of crustal sulphur increased the volatile budget of HALIP magmas, which therefore could have contributed to a deterioration of the environmental conditions during the emplacement of the HALIP. / Stora magmatiska provinser (på engelska Large Igneous Provinces, LIPs) är vulkaniska event då enorma mängder magma avsätts över en väldigt stor yta under ett, i ett geologiskt perspektiv, kort tidsspann. Dessa stora vulkaniska utbrott har väckt stort intresse då de är samtida med flera av de största massutdöendena i jordens historia, men också för att en viss typ av sulfidmalm rik på nickel, koppar och platinametaller (Ni-Cu-PGE malmer) ofta förekommer i provinsernas magmagångar och magmakammare. En viktig faktor som till stor del avgör en magmatisk provins påverkan på klimatet och potentiella malmförekomster är inkorporering av sedimentära bergarter till magman som, när de hettas upp, kan frigöra gaser rika på svavel och kol. I Kanadas arktiska öar trängde magma tillhörande den högarktiska magmatiska provinsen (HALIP) in i svart skiffer, karbonater och evaporiter, som är sedimentära bergarter rika på flyktiga ämnen. Denna magmatiska provins erbjuder därför stora möjligheter till att studera interaktionen mellan magma och sedimentära bergarter. Syftet med denna studie är att testa om inkorporering av sedimentärt svavel kan främja bildandet av sulfidsmälta i magma och därigenom bidra till bildandet av sulfidmalmer. Detta görs genom att analysera svavelisotoper i sulfidmineral i prover från en magmagång, som trängde in i en skifferformation, tillhörande den högarktiska magmatiska provinsen i norra Kanada. Genom att analysera svavelisotopkvoten (δ34S) i sulfidmineral kan man få information om huruvida svavlet i mineralen är av sedimentärt ursprung (där skiffer generellt har negativa δ34S värden) eller om svavlet har δ34S värden liknande de från manteln (som har δ34S värden runt 0‰), vilket i så fall skulle innebära att magman inte har inkorporerat sedimentärt svavel. Genom att använda masspektrometri av typen SIMS analyseras totalt 14 sulfidmineralkorn (n = 246 individuella SIMS punkter) för deras svavelisotopkvoter. Resultatet av studien visar att alla analyserade sulfidmineral har mycket negativa δ34S värden mellan -19.5 och -5.7‰ (med ett δ34S medelvärde på -8.2 ± 0.83‰, två standardavvikelser). Genom att jämföra våra δ34S värden med δ34S och δ18O värden för andra prover från både magmagången och den omgivande skiffern kunde vi se att δ34S värdena för sulfidmineralen i de yttre delarna av magmagången har liknande negativa värden som den omgivande skiffern, och att δ34S värdena för skiffern närmast magmagången är mer positiva. Detta tyder på att sedimentärt svavel i kontakten mellan magmagången och skiffern har blivit inkorporerat i magman från den omgivande skiffern. Våra resultat tyder därför på att sulfidmineralen i våra prover från magmagången bildades genom assimilering av svavel från den omgivande skiffern. Detta innebär i sin tur att den kanadensiska högarktiska magma provinsen potentiellt kan vara en källa för sulfidmalm, även om ytterligare studier behövs. Dessutom visar våra resultat att inkorporering av sedimentärt svavel förmodligen ökade de vulkaniska gaserna i magman, vilket kan ha bidragit till klimatförändringar relaterade till den vulkaniska aktiviteten av den högarktiska magmatiska provinsen.

This project aims to develop standards to predict vermillion border shape and appearance - i.e. the outline of the vermillion border and the fullness of lips, based on assessment of an individual dental pattern using a combination of three methods: morphological, cephalometric and GMM. This study tests a hypothesis that the skeletal and dental pattern in antero-posterior and vertical dimensions and the upper and the lower incisor inclinations can predict the morphology of the soft tissue of the lips. This hypothesis was examined by analysing retrospective facial data, which consists of two-dimensional, pre-orthodontic treatment photographs and cephalograms of individuals of four malocclusion classes: Class I, Class II: divisions 1 and 2, and Class III from two sample populations: 56 Scottish and 56 Jordanians, aged 11-14 years. All the Scottish participants had been recipients of treatment at the Dental Hospital at the University of Dundee, and the Jordanian sample were selected from the Orthodontic archive held by Jordan University Hospital. The results reveal that a cephalogram analysis offers a statistically significant correlation differing from one type of malocclusion to another, in addition, analysis of cephalograms showing the value of angles and linear dimensions differed from one type of malocclusion to another. Photographic analysis using GMM afforded a statistically reliable correlation between naso-labial traits, and particularly between the vermillion border outline and malocclusion patterns. Due to their shared ancestry (Caucasian), both Jordanian and Scottish populations showed the same morphological trends for the lips, for example: long lower facial height, a deep philtrum, V-shaped Cupid’s bow, thin upper vermillion border. GMM results suggest that vermillion border variation could be computed, at least when distinguishing between malocclusion classes from the same ethnic group. Morphological, GMM, and cephalograms analyses confirmed that the shape and diversity in the Vermillion XIV border outline differed between malocclusion classes, but few or no differences could be shown between the sexes.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 6, 2008) Includes bibliographical references.

Thesis (M.S. in oral sciences)--University of Illinois at Chicago, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S. in oral sciences)--University of Illinois at Chicago, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Københavns Tandlaegehøjskole. / At head of title: From the Department of Oral Diagnosis, Royal Dental College, Copenhagen, Denmark. Includes bibliographical references (p. 198-217) and index.

Thesis--Københavns Tandlaegehøjskole. / At head of title: From the Department of Oral Diagnosis, Royal Dental College, Copenhagen, Denmark. Includes bibliographical references (p. 198-217) and index.