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With the advent of cephalometrics in the 1930s, numerous studies have focused on the profile of a face to achieve a more esthetic orthodontic treatment outcome. With such heavy emphasis on facial esthetics, a shift in focus from the profile view to the oblique view has become necessary as the smile in the oblique view is what the general public evaluates. The purpose of this pilot study was to determine whether the current tools for diagnosis and treatment evaluation are sufficient. Currently, 2-dimensional composite photographs are utilized in evaluating the soft tissue. At Temple University, 3-dimensional images, which show all sides of the patient's face, are used adjunctively to 2-dimensional composite photographs. In this study, faculty members at the Temple University Department of Orthodontics were asked to complete surveys after viewing two different image modalities, 2-dimensional images and a 3-dimensional video of the same patient. They were asked to fill out the soft tissue goals for specific facial landmarks. Patient photos were in the smiling view as current literature lacks studies on this view. Faculty members' responses from analyzing the 2-dimensional images and 3-dimensional video for each patient were compared to determine which areas had frequent discrepancies from using two different image modalities. During the survey, a voice recorder captured any comments regarding the images. The ultimate goal of this qualitative pilot study was to identify when 3-dimensional imaging is necessary in treatment planning and evaluation, with an added hope to further advance research in 3-dimensional imaging and its vast possibilities to advance the field of orthodontics. Based on the data collected, the following conclusions were made: 1. The qualitative data highlighted that 3-dimensional imaging would be necessary in cases with skeletal deformities. 2. In the oblique view, 3-dimensional imaging is superior than 2-dimensional imaging by showing more accurate shadow, contour, and depth of the soft tissue. 3. Further improvement is necessary to create a virtual patient with treatment simulation abilities. 4. The comfort level among orthodontists of 2-dimensional imaging was higher than 3-dimensional imaging. With more widespread use of 3-dimensional imaging, more orthodontists may gradually reach a higher comfort level in using this relatively new technology. 5. Faculty members expressed high willingness to use 3-dimensional imaging if improvement in new technology could allow for more manipulation and accurate soft tissue prediction. 6. 3-dimensional imaging is superior in its efficiency, quick capture time, and lack of need for multiple images. Implementation of 3-dimensional imaging could streamline the records process and help with practice efficiency without compromising the image quality. 7. Both patients and orthodontists may benefit from using 3-dimensional imaging. Patients can see an accurate representation of themselves and possibly view their own treatment simulation upon further improvement in current technology. Orthodontists would benefit with much more accurate images that may serve as the virtual patient. 8. Besides the exorbitantly high cost, faculty members thought that more advances were needed and the current benefit was not great enough to justify the investment. The results were consistent with other studies that used the oblique view in that the 2-dimensional oblique view lacks depth and does not provide adequate information. With further improvement in current 3-dimensional imaging, this technology can benefit orthodontists in visualizing their patients. In addition, patients can benefit by hopefully seeing a live and accurate simulation of themselves instantly as a virtual patient. With these benefits of 3-dimensional imaging, it may one day be the new standard in patient records in the field of orthodontics. / Oral Biology

This research aims to develop a tissue-mimicking material and produce a 3D gelatin that has density of approximately a human lung, which is in the ranges of (0.25 – 0.35) g/cm3. Tissue equivalent models are important in order to study the radiation dose planned for patients. To achieve the desired density of a human tissue, different types of gelatin were whisked for 300 seconds using a typical hand mixer. The mechanical properties of the gelatin mixtures, standard and foamed, were evaluated by applying different forces. The mechanical properties for the gels were measured using an indentation technique, which showed that the gels act as elastic materials. The mechanical properties of the foams were also evaluated. Mixtures that contained 300 bloom gelatin, glycerol, and sorbitol, were whisked for 60, 180, 300 seconds to achieve different densities evaluated by CT imaging. The density of the180 - and 300 - seconds gelatin foams were found to be 0.33 ± 0.16 and 0.33  0.052 g/cm3, respectively, which is similar to the human lung density. Finally, FXO gel sheets and the FXO foam sheets were irradiated and the radiosensitivity quantified by measuring transmission using a spectrometer. The change in the attenuation coefficient was linear with dose. / Thesis / Master of Science (MSc)

This dissertation describes the preparation of a novel inorganic membrane for hydrogen permeation and its application in a membrane reactor for the study of the methane steam reforming reaction. The investigations include both experimental studies of the membrane permeation mechanism and theoretical modeling of mass transfer through the membrane and simulation of the membrane reactor with 1-D and 2-D models. A hydrothermally stable and hydrogen selective membrane composed of silica and alumina was successfully prepared on a macroporous alumina support by chemical vapor deposition in an inert atmosphere at high temperature. Before the deposition of the silica-alumina composite, multiple graded layers of alumina were coated on the alumina support with a mean pore size of 100 nm by the sequential application of three boehmite sols with gradually decreasing sol particle sizes of 630, 200 and 40 nm, respectively. The resulting supported composite alumina-silica membrane had high permeability for hydrogen in the order of 10-7 mol m-2 s-1 Pa-1 at 873 K with a H2 /CH4 selectivity of 940 and exhibited much higher stability to water vapor at the high temperature of 873 K. In addition, the same unusual permeance order of Heï¼ H2ï¼ Ne previously observed for the pure silica membrane was also observed for the alumina-silica membrane, indicating that the silica structure did not change much after introduction of the alumina. The permeation of hydrogen and helium through vitreous glass and silica membranes was modeled using ab initio density functional calculations. Comparison of the calculated activation energies to those reported for vitreous glass (20—40 kJ mol -1) indicated the presence of 5- and 6-membered siloxane rings, consistent with the accepted structure of glass as a disordered form of cristobalite. The experimental studies of the steam reforming of methane were examined at various temperatures (773-923 K) and pressures (1-20 atm) with a commercial Ni/MgAl2O4 catalyst in a hydrogen selective silica-alumina membrane reactor and compared with a packed bed reactor. One-dimensional and two-dimensional modeling of the membrane rector and the packed bed reactor were performed at the same conditions and their performances were compared with the values obtained in the experimental study. Improved methane conversions and hydrogen yields were obtained in the membrane reactor compared to the packed bed reactor at all temperatures and pressures. From the two modeling studies, it was also found out that the two-dimensional model performed better in the membrane reactor case especially at higher pressures. / Ph. D.

A confecção de trabalhos protéticos em um fluxo digital é possível a partir do escaneamento intra-oral e confecção da Prótese via CAD/CAM. A tecnologia atual de impressão 3D permite a obtenção de um modelo impresso, para a realização de determinados procedimentos. Entretanto, é necessário analisar e comparar estes modelos com os modelos de gesso, uma vez que existe uma diferença significativa na forma de obtenção, assim como, nos custos de cada tipo de modelo. O presente estudo teve como objetivo realizar uma análise da acurácia entre modelos impressos, obtidos por meio de escaneamento intra-oral e impressão 3D, e modelos de gesso obtidos pelo método de moldagem convencional. Foi utilizado um manequim odontológico como modelo mestre e foram confeccionados dez modelos de gesso (n= 10), pela técnica de moldagem da dupla impressão com silicone de adição. Foram utilizados dois tipos de escâneres intra-orais e dois tipos de impressoras 3D, que formaram quatro grupos experimentais com dez modelos por grupo (n= 10). Os modelos físicos de gesso e impressos foram comparados com o modelo mestre por meio de análises de medições lineares em seis sítios de medições, com o uso de uma máquina de medição por imagem (Quick Scope, Mitutoyo®). A análise dos modelos impressos incluiu as possíveis interações entre os fatores principais tipo de impressora, tipo de escâner e sítios de medições. Os resultados mostraram que em relação ao modelo mestre, no geral, as discrepâncias dos modelos de gesso foram menores que as discrepâncias dos modelos impressos. A análise das interações dos fatores principais indicou que o tipo de impressora exerceu a maior influência na acurácia dos modelos impressos, seguido do fator sítio de medição e tipo de escâner. Pôde-se concluir que os modelos de gesso apresentaram uma acurácia superior quando comparados com os modelos impressos. O acabamento superficial dos modelos impressos exerceu influência na sua acurácia. / The preparation of prosthetic restoration in a digital flow is possible using intraoral scanning and confection of the prosthesis via CAD/CAM. The current 3D printing technology allows the making of a printed cast, for performing certain laboratory procedures. However, it is necessary to analyze and compare these casts with the gypsum casts, since there is a significant difference in the form of obtaining, as well as, in the costs of each type of cast. The objective of the present study was to perform a comparative study of the accuracy of printed casts, obtained through intraoral scanning and 3D printing, and gypsum casts, obtained through the conventional impression. A dental mannequin was used as the master model and ten gypsum casts (n=10) were obtained, using double impression technique with polyvinyl siloxane. Two types of intraoral scanners and two types of 3D printers were used, which formed four experimental groups with ten models per group (n=10). The real gypsum and printed casts were compared to the master model by linear measurements in six sites, using an image-measuring machine (Quick Scope, Mitutoyo®). The analysis of the printed models included possible interactions between the factors type of printer, type of scanner and measurement sites. The results showed that, in relation to the master model, in general, the discrepancies of the gypsum casts were smaller than the discrepancies of the printed casts. The interactions of the factors analysis indicated that the type of printer exerted the greatest influence on the accuracy of the printed casts, followed by the site measurement and type of scanner. It was conclude that the gypsum casts presented superior accuracy when compared to the printed casts. The surface finish of the printed casts exerted influence in its accuracy.

Selective laser melting process is an additive manufacturing technique that allows obtaining, from a 3D model, a physical model through a layer-by-layer manufacturing strategy. Several machines are commercially available, known as 3D printers. Recently, technology improvements have allowed the use of metallic materials; however, the amount of materials available is low due to the difficulty to find adequate manufacturing parameters. The thesis proposes a methodology, using an inclined plane, to set the minimum energy density to melt a continuous track, the first step of the melting process. Different process parameters from several commercials machines have been used to evaluate dimensional and mechanical properties. Replicas of traditional products have been fabricated using additive process and they have been compared. Finally, a protocol to use a selective laser melting process to reconstruct a personalized jaw prosthesis has been shown / La fusió selectiva per làser és un procés de fabricació additiva que permet obtenir, d'un disseny en 3D, un model físic de forma ràpida i a través d'una estratègia de fabricació capa a capa. Existeixen diferents màquines comercials anomenades impressores 3D. Actualment, les millores tècniques desenvolupades han permès la utilització de materials metàl·lics, no obstant, la quantitat de materials que es poden utilitzar és baix degut a la dificultat per trobar els paràmetres de fabricació més adequats. La tesis proposa una metodologia, a través d’un pla inclinat, que permet definir la densitat d’energia mínima per fondre un cordó continu, el primer pas del procés de fusió làser. Diferents paràmetres de varies màquina comercials s'han utilitzat per avaluar variables dimensionals i mecàniques. S'han comparat rèpliques fabricades mitjançant processos tradicionals i processos additius. Finalment, s'ha realitzat un protocol per a reconstruir una mandíbula personalitzada utilitzant la fusió selectiva per làser

Direct Metal Laser Sintering (DMLS) is a rapid prototyping technique that allows for direct and rapid manufacturing of complex components. DMLS is however an intricate process and the quality of the final product is influenced by multiple manufacturing parameters (or DMLS settings) and powder characteristics. The effect which each of these manufacturing parameters and powder characteristics has on the final parts is not well understood and the success of process manufacturing mainly relies on empirical knowledge. Consequently high dimensional deformation and relatively poor mechanical properties are still experienced in many DMLS products, in particular in copper-based laser sintered parts. A need therefore exists to systematically examine the effect of process parameters on the quality of final parts in order to determine the most appropriate manufacturing parameters for specific applications of copper-based laser sintered parts. This document summarises the effect of different process parameters on the quality of Direct Metal 20 laser sintered parts produced with a EOSINT M250 Xtended laser sintering machine from powder consisting of Ni5Cu, Cu15Sn – Cu5Sn and Cu8P – Cu2P material grains. The quality of the sintered parts is defined in terms of the microstructures, porosities and dimensional deformations obtained. The effects of three different geometric sintering strategies currently in standard use namely Solid Skin, Skin Stripes and Skin Chess were examined, and the more appropriate process parameters and scanning technique for the available set-up is presented. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Direct Metal Laser Sintering (DMLS) is a rapid prototyping technique that allows for direct and rapid manufacturing of complex components. DMLS is however an intricate process and the quality of the final product is influenced by multiple manufacturing parameters (or DMLS settings) and powder characteristics. The effect which each of these manufacturing parameters and powder characteristics has on the final parts is not well understood and the success of process manufacturing mainly relies on empirical knowledge. Consequently high dimensional deformation and relatively poor mechanical properties are still experienced in many DMLS products, in particular in copper-based laser sintered parts. A need therefore exists to systematically examine the effect of process parameters on the quality of final parts in order to determine the most appropriate manufacturing parameters for specific applications of copper-based laser sintered parts. This document summarises the effect of different process parameters on the quality of Direct Metal 20 laser sintered parts produced with a EOSINT M250 Xtended laser sintering machine from powder consisting of Ni5Cu, Cu15Sn – Cu5Sn and Cu8P – Cu2P material grains. The quality of the sintered parts is defined in terms of the microstructures, porosities and dimensional deformations obtained. The effects of three different geometric sintering strategies currently in standard use namely Solid Skin, Skin Stripes and Skin Chess were examined, and the more appropriate process parameters and scanning technique for the available set-up is presented. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

M. Tech. Civil Engineering / Asphalt mixes are commonly used for paving roads around the world. They consist of mainly bitumen and aggregate materials, which may differ depending on the type of asphalt mix. The shape properties of aggregate particles relevant for the performance of asphalt mixes include the form, angularity and surface texture. There are concerns about the standard test methods used to quantify the shape properties (i.e. angularity, surface roughness, flatness, elongation and sphericity) of aggregates used for road pavement design and construction. These test methods have been reported as time and labour intensive, and have several limitations including human error, lack of accuracy, and repeatability of test results. Although results obtained from these tests have been linked to performance, however these links are questionable. Recently, various researchers and practitioners have indicated that advanced and automated approaches such as imaging and laser scanning techniques would better quantify the shape and surface properties of aggregates. For instance, researchers at the Council for Scientific and Industrial Research (CSIR) found that a portable three-dimensional (3-D) laser scanning system can be used to accurately quantify the shape properties of aggregate particles that are relevant to the performance of asphalt mixes. The overall objective of this study was to use a 3-D laser scanning technique to quantify the shape properties of aggregate materials and relate them to performance of laboratory compacted asphalt mixes.

Rwanda experienced one of the most horrendous atrocities in our modern history in the summer of 1994 when a genocide occurred within the country, and in the aftermath the nation had to deal with this history and rebuild its society. This essay examines the reconciliation in post-genocide Rwanda with the aim of investigating potential power mechanisms during this process. The study researches the policies implemented by the government of Rwanda during this process and what effect they potentially can have on the reconciliation in the country. The focus is on the policy of National Unity and Reconciliation and two of the main instruments within this government policy, which are Gacaca and Ingando. The analytical framework for this study is Steven Lukes’ theory on three-dimensional power, which was applied as an analytical lens to examine the power exercise by the RPF government. The essay used an abductive approach to research the subject and a case study as the chosen method for the study. The results of the research confirms that there are several instances of power exercise, both within the two and three-dimensional concept of power as described by Lukes. Certain aspects of the RPF’s policies aimed at reconciliation can be seen as power exercise by the government and potentially be problematic for a successful reconciliation process.