Dissertations / Theses on the topic 'Texture and its Formation'
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Xu, Wanqiang Materials Science & Engineering Faculty of Science UNSW. "Effect of initial microstructure on the deformation and annealing behaviour of low carbon steel." Awarded by:University of New South Wales. School of Materials Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/26801.
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The effect of initial microstructures of an 0.05 wt.% C low carbon steel, acicular ferrite (AF), Bainite (B), polygonal ferrite (PF), fine polygonal ferrite (FPF), and a microstructure produced by direct strip casting (DSC) (termed SC), on the deformation and recrystallization behaviour of cold rolled low carbon (LC) steel, was investigated. The initially prepared samples with the initial microstructures were cold rolled to 50, 70 and 90% reductions, then annealed isothermally in the temperature range 580 ??? 680 oC. The microstructures and textures produced by deformation and annealing were studied by optical microscopy, XRD, TEM, SEM and EBSD. The initial microstructures were characterized mainly by optical microscopy and EBSD. Using EBSD, the ferrite grain size of the AF, B and SC samples was considerably larger than that found by optical microscopy with a large fraction of low angle grain boundaries (LAGBs) observed within prior austenite grains. All samples exhibited a very weak texture close to random. After cold rolling, the microstructures of AF and SC contained shear bands with PF and FPF generating deformation bands. For AF and SC, the pearlite phase was more extensively elongated in rolling direction compared with PF and FPF. After 90% cold rolling reduction, PF, FPF and SC consist mainly of the texture component and AF and B . It was found that FPF recrystallized most rapidly followed by B, PF and AF with SC recrystallizing orders of magnitude more slowly due to the solution drag caused by its uniformly distributed higher Mn content. Very strong (???-fibre) texture was generated in cold rolled PF followed by FPF, with AF, SC and B generating very weak textures. The texture evolution during annealing 90% reduction PF was examined in further detail. The behaviour of nucleation and grain growth provides strong evidence of orientated nucleation as the dominant factor for CRA texture development in this material.
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Koralegedara, Nadeesha H. "Chemical, Mineralogical and Textural Properties of the Kope Formation Mudstones: How They Affect its Durability." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307109253.
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Li, Dongyang. "Texture formation in iron electrodeposits." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29076.
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The texture of electrodeposits has attracted increasing interest, as it is recognized that it is a possible to benefit from the texture and to improve the various properties of electrodeposits or electrolytic coatings. For example, the corrosion resistance of materials is affected by texture. If appropriate textures are introduced in electrodeposited coatings, their corrosion resistance would be enhanced and the coatings will therefore have a longer service time. Texture development during electrodeposition is still poorly understood, and this makes it difficult to control the texture formation during the electrodeposition processes. In order to better understand the texture formation during electrodeposition, extensive theoretical and experimental investigation are undertaken in this thesis.A computer model was proposed to describe texture development. In this model, the microstructure of deposit was represented using a two dimensional triangle lattice. The deposit growth was modelled as previously empty lattice sites are being occupied based on fundamental physical rules. The author proposed that the main driving force for the development of microstructure and texture is the minimization of the system's free energy. This results in texture development, and the minimization of the free energy includes deposit's surface energy and occasionally the magnetic energy. Based on this hypothesis, the texture formation during iron electrodeposition and its variation with the deposition condition were simulated. It was demonstrated that the crystallographic anisotropy of deposit's surface energy plays an important role in the formation of the deposit's fibre texture. The study also indicated that the surface-energy anisotropy could be modified by hydrogen co-deposition and the deposit's texture can be modified by varying the current density, temperature, or pH value of the bath. In addition, the study illustrated that the magnetization energy also plays an important role in texture development during electrodeposition of magnetic materials. When external magnetic fields of sufficient strength are applied during the deposition of magnetic materials, the magnetic fields align grains in such a way that the deposits' fibre textures may transform to non-fibre textures.
In order to further justify the minimum-energy texturing mechanism proposed in the model, and to obtain a clear physical picture of the texture formation during electrodeposition, the process of texture development was analyzed using classical thermodynamics. Various experiments were conducted to verify the computer simulation. A positive correlation between the results of the simulation and the experiments were found.
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Rzadca, Mark C. "Multivariate granulometry and its application to texture segmentation /." Online version of thesis, 1994. http://hdl.handle.net/1850/12200.
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Thamburaja, Prakash 1974. "Shape memory materials : crystallographic texture and its consequences." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/88855.
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Yan, Jun 1974. "Theory and simulation of texture formation in mesophase carbon fibers." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34001.
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Carbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of fiber textures and cross-sectional shapes. The circular planar polar (PP), circular planar radial (PR), ribbon planar radial (RPR), and ribbon planar line (RPL) textures are the most frequently observed in industrial fiber making. This thesis presents, solves, and validates models of mesophase fiber texture formation based on the classical Landau-de Gennes theory of liquid crystals, adapted here to carbonaceous mesophases. The model captures the microstructure and the formation of the four (PP, PR, RPR, RPL) textures. In cylindrical fibers, the computed PP and PR textures phase diagram, given in terms of temperature and fiber radius, establishes the processing conditions and geometric factors that lead to the selection of these textures. The influence of elastic anisotropy to the textures' formation and structure is thoroughly characterized. The multi-stage formation process of the PP texture is reproduced, including defect nucleation, defect migration, and overall texture geometry. The mechanisms that control the PP texture geometry are characterized using analytical methods. The role of elasticity and flow-induced orientation on texture selection mechanism in ribbon-shaped mesophase fibers are characterized using an anisotropic viscoelastic model. The model is able to predict the formation of the commonly observed line defect in the RPL texture, and the fine structure of the line is reproduced and explained in terms of classical liquid crystal defect physics. The results of this thesis provide new knowledge on how to optimize and control mesophase fiber textures.
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Murakami, Kenichi. "Etude et modélisation des mécanismes de formation des textures de recristalisation dans les aciers Fe-Si." Paris 13, 2008. http://www.theses.fr/2008PA132004.
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Les aciers électriques non-orientés sont utilisés comme noyaux de moteurs. Notre étude concerne les mécanismes de formation des textures dans ces aciers par SIBM (strain induced boundary migration) lors du recuit final. Après 5% de laminage et recuit, la texture passe d’une fibre à une orientation proche de Goss. L’analyse en MET montre que l’énergie stockée est minimale dans Goss, maximale dans {111}<112> et intermédiaire dans D-Cube ({100}<011>. Après 9% de déformation, les sous-structures de Goss sont hétérogènes et celles de D-Cube sont homogènes : 2 types de systèmes sont actifs dans D-Cube mais un seul dans Goss. Cette orientation a donc une plus grande capacité de restauration et une plus grande facilité de croissance par SIBM. Ce mécanisme a été étudié également dans des échantillons d’aluminium : les grains d’orientations {110}<111> et {110}<112> – associés à un faible nombre de systèmes actifs – croissent par SIBM. On en conclue donc que c’est le paramètre dominantThe present study clarifies the mechanism of texture formation during strain induced boundary migration in electrical steels. After 5% reduction of temper rolling and annealing, texture changes from -fibre to near-Goss through SIBM. TEM analyses after rolling reveal that Goss has the smallest stored energy, {111}<112> the largest and D-Cube ({100}<011>) is in between. After 9% strain, substructures are heterogeneous in Goss and homogeneous in D-Cube. The specific features of Goss could be explained by the arrangements of slip systems; two systems are simultaneously active in D-Cube but only one in Goss. Therefore, Goss grains are easy to recover and are preferable nuclei in SIBM. In order to transpose this SIBM mechanism to fcc materials, extruded Al blocks are analyzed. During SIBM, grains with {110}<111> and {110}<112> orientations – associated with small numbers of activated systems – grow large. Capacity of SIBM is thus assumed to be linked to smaller number of active systems
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Hort, Joanne. "Cheddar cheese : its texture, chemical composition and rheological properties." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/19833/.
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Procedures associated with Quantitative Descriptive Analysis were used to identify and subsequently train a panel to quantify the perceived textural attributes of Cheddar cheese. Seventeen types of Cheddar were assessed by the panel for creaminess, crumbliness (fingers), crumbliness (chewing), firmness, graininess, hardness (first bite), hardness (cutting), and springiness. Cluster and Principal Component analyses of the sensory data revealed that the cheese samples could be subdivided into young, mature and extra mature Cheddars in terms of the textural attributes measured. The panel was also able to distinguish between the low fat and genuine Cheddars. The percentage fat, moisture and salt contents and the pH level of the seventeen Cheddar samples were established. An inverse correlation between fat and moisture content and a positive correlation between pH level and salt content were observed. The rheological properties were measured using three tests performed on an Instron Universal Testing Machine - a compression test, a cutting test and a stress relaxation test - and, where appropriate, were reported in terms of true stress and true (Hencky) strain curves. The viscoelastic properties of Cheddar observed during stress relaxation tests were modeled using a Generalised Maxwellian model consisting of two exponential elements and a residual term. Considerable variation in all the rheological properties was observed amongst the Cheddar samples. The rheological parameters did not distinguish between the samples to the same extent as the sensory assessment. However, Cluster Analysis of the rheological data did differentiate between the rheological profiles of the young (mild & medium) and the remaining mature/extra mature samples. The relationships between the textural attributes and the chemical and rheological parameters were investigated. No relationship between chemical composition and texture was identified, but correlations between the rheological parameters and the textural attributes were not uncommon. Multiple regression techniques were employed to construct mathematical models to predict the textural attributes from the rheological data. Successful models were constructed utilising parameters from the compression and cutting tests for all the attributes apart from creaminess. More precise models were constructed for firmness, springiness and crumbliness (fingers) where the action of the instrumental test from which the rheological parameters were obtained resembled the test method used by the panel. The chemical, textural and rheological properties of an English Cheddar were determined at various stages during its ripening period to investigate any changes that occurred. A slight increase in pH was the only chemical change recorded. Progressive changes in the majority of the textural attributes were observed. The most dramatic changes included a decrease in springiness and an increase in creaminess. A changing rheological profile was also observed during maturation, a decreasing strain at fracture being the most notable development. The sequence of changes in both the textural and rheological properties was divided into three fairly distinct phases, the initial stage reflecting the developments necessary before the cheese would be suitable for retail sale and the final stage including the development of the necessary textural attributes characteristic of a Mature English Cheddar. It was evident that the timing of the maturation period was pertinent to the development of textural attributes characteristic of particular maturities of Cheddar cheese. The textural attributes of the maturing Cheddar were also predicted at each stage of maturation using the mathematical models constructed in the initial study. Accurate predictions were made for all the attributes except crumbliness (chewing) and graininess.
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Wollschläger, Daniel. "Dynamic surface completion the joint formation of color, texture, and shape /." [S.l.] : [s.n.], 2006. http://e-diss.uni-kiel.de/diss_1637/d1637.pdf.
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Mohamed, Wan Abd Malik Wan. "Analysis of surface texture and its affect on pressure balances." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/33658.
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There are two primary methods to derive pressure from the base units of mass, length and time, i.e. a liquid manometer and a pressure balance. The key problem associated with pressure measurement using a pressure balance is centred on the determination of the effective area of the piston-cylinder assembly (PCA) under the appropriate operating conditions. Dimensional measurements alone cannot provide formally recognised traceability to the SI unit, the pascal (Pa), without extreme levels of data and mathematical modelling, supported with extensive comparison histories with other instruments of proven performance. Intercomparisons have demonstrated that the uncertainty of measurements using pressure balances, have reached a plateau of approximately 5 to 10 ppm due to unexplained phenomena. The aim of this research is to identify any evidence of pressure dependency as a function of surface texture applied onto the piston of 35 mm diameter PCA, using a gas-operated (gas-lubricated) pressure balance.
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Liang, Yuan. "Ultrasonic Nanocrystal Surface Modification Produced Surface Texture and Its Applications." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510277965591045.
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Obasi, Gideon Chima. "Variant selection and its effect on texture inTi-6Al-4V." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/variant-selection-and-its-effect-on-texture-inti6al4v(7e9255ab-62c2-42ee-91ce-fe3c0fa24bea).html.
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Titanium alloys are strong candidates for the aerospace industry and biomaterial applications because of their low density, high strength-to-weight ratio and very high strength even at temperatures up to 600°C. Like many other engineering alloys, titanium alloys are prone to strong preferred crystallographic orientation development during thermomechanical processing. Part of the titanium processing route is to heat treat the material above the β transus for the purpose of homogenization and associated phase transformation. This heat treatment dramatically affected the microstructure and texture evolution. Theoretically, such heat treatment should result in a nearly random texture if all variants during α→β→α phase transformation are active. In reality, significant textures are observed after such a heat treatment process. The present project aims at developing a detailed understanding of the root cause for this relatively strong texture by means of EBSD and in-situ neutron diffraction studies. The effect of β grain growth on variant selection during β to α phase transformation has been investigated by using two variants of Ti-6Al-4V with and without 0.4 wt% yttrium addition. The aim of adding yttrium was to control β grain growth above the β transus by pinning grain boundaries with yttria. Both materials were first thermomechanically processed to generate a similar starting microstructures and crystallographic textures. Subsequently, both materials were solution heat treated above the β transus followed by slow cooling to promote growth of the α lath structure from grain boundary α. Detailed EBSD and in situ neutron diffraction analysis were carried out to study microstructure and texture evolution. The variant selection calculation suggests that more variant selection occurred in convectional material with a large grain size compared to material with yttrium addition. In situ measurements showed that β texture strengthened significantly above the β transus with increasing β grain size. There was no significant variant selection during α→β transformation; variant selection noticeably increased during β→α transformation with increasing β grain size. Additional interrupted cooling experiments followed by EBSD analysis showed early nucleation of α variants with a 'butterfly morphology' from β grain boundaries that have a pair of β grain with a common <110> pole. These observations suggest reduced nucleation energies for α formation in such circumstances allowing extensive growth of these α variants into unoccupied β grains making it a dominant variant. The influence of rolling temperatures (i.e. at 800 ºC and 950 ºC) to produce different starting texture, on texture evolution and variant selection during α→β→α transformation was also investigated. Laboratory X-ray, EBSD and in-situ neutron diffraction texture analyses were carried out. Even though the transformation texture is stronger at 800 ºC, the degree of variant selection is stronger in materials rolled at950 ºC compared to material rolled at 800 ºC. Here, the enhanced variant selectionfor the material rolled at 950 ºC was related to the different β texture. It is suggested that the combination of a particular β texture components promote variant nucleation that can increase the likelihood of having β grain pairs with a common <110> pole.
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Li, Hualong 1967. "Computer simulation of oxide texture and microstructure formation and their effects on oxidation kinetics." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35467.
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Computer models of oxide texture and microstructure development and oxidation kinetics have been developed. The first computer model enables the evaluation of the effects of various factors on oxide texture and microstructure development. The second computer model enables the evaluation of the effects of oxide texture and microstructure on oxidation kinetics.Two examples of Ni single crystal and polycrystalline, Zr-2.5%Nb are used to illustrate the proposed computer models. Simplified oxidation mechanisms on Ni and Zr have been proposed.
In the first system, the simulation of oxide texture and oxidation kinetics on the {100} and {111} oriented single crystal Nickel substrate is analyzed. At the nucleation stage the oxide grain orientation is determined by lattice matching between the oxide and the metal substrate. At the stage of oxide grain growth, oxide surface free energy plays an important role. The simulated oxide textures are in good agreement with experimental results. The observed difference in the oxidation kinetics of the two samples is explained by difference in oxide textures formed on the two single crystal substrates. The high percentage of Sigma3 twin boundaries found in the oxide formed on the {111} substrate indicates that the presence of these boundaries significantly improves oxidation resistance.
In the second system where oxidation on Zr-2.5%Nb is simulated and analyzed, lattice matching between the oxide and the metal substrate is used to determine the oxide orientation at the nucleation stage. At the stage of oxide grain growth, oxide orientation is determined by minimizing the compressive stress that is parallel to the metal/oxide interface. Four samples with different substrate orientations have been used in study. The simulated oxide textures and microstructures are in good agreement with experimental results. During the simulation of oxidation kinetics, it is found that oxygen transport through Zr oxide film takes place mainly through two diffusion paths. The first diffusion path is through oxide grain boundaries formed in the bulk alpha-Zr grain region and the second one is through oxide grain boundaries formed at the alpha-Zr grain boundaries and beta-Zr grain region.
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Li, Hualong. "Computer simulation of oxide texture and microstructure formation and their effects on oxidation kinetics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0014/NQ50208.pdf.
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Dunn, Adele. "Textural variability in chicken breast meat and its control." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238951.
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Blandford, Peter. "Through-thickness inhomogeneity of steel-sheet texture and its affect on material properties." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59295.
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The work of this thesis centres around two related themes, the first being the characterization of the through-thickness inhomogeneity found in rolled sheet at various stages in its production. The second is involved with attempting to understand how and to what extent the existing inhomogeneity affects the correlations with the anisotropies of some physical or mechanical properties. For this, the inhomogeneity of six steels were measured.Three were specimens removed from the sheet during the early processing of conventional grain-oriented ferrosilicon steel, one sample taken after the first cold rolling stage, another taken after the intermediate anneal, while the last was taken after the following stage, i.e. after the second cold rolling.
To contrast the extensive inhomogeneity expected in the ferrosilicon steels, the remaining three steels consisted of two continuous-annealed, interstitial-free, extra-low-carbon steels and one aluminum-killed, batch-annealed, low-carbon steel, all three of which are commercial final product, deep drawing steels.
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Cargill, Ellen Bernadette. "A mathematical liver model and its application to system optimization and texture analysis." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184936.
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This dissertation presents realistic mathematical models of normal and diseased livers and a nuclear medicine camera. The mathematical model of a normal liver is developed by creating a data set of points on the surface of the liver and fitting it to a truncated set of spherical harmonics. We model the depth-dependent MTF of a scintillation camera taking into account the effects of Compton scatter, linear attenuation, intrinsic detector resolution, collimator resolution, and Poisson noise. The differential diagnosis on a liver scan includes normal, focal disease, and diffuse disease. Object classes of normal livers are created by randomly perturbing the spherical harmonic coefficients. Object classes of livers with focal disease are created by introducing cold ellipsoids within the liver volume. Cirrhotic livers are created by modelling the gross morphological changes, heterogenous uptake, and decreased overall uptake. Simulated nuclear medicine images are made by projecting livers through nuclear imaging systems. The combination of object classes of simulated livers and models of different imaging systems is applied to imaging-system design optimization in a psycho-physical study. Human observer performance on simulated liver images made on nine different systems is compared to the Hotelling trace criterion (HTC). The system with the best observer performance is judged to be the best system. The correlation between the human performance metric dₐ and the HTC for this study was 0.829, suggesting that the HTC may have value as a predictor of observer performance. Texture in a liver scan is related to the three-dimensional distribution of functional acini, which changes with disease. One measure of texture is the fractal dimension, related to the Fourier power spectrum. We measured the average radial power spectra of 70 liver scans. All of these scans yield straight lines when plotted on a log-log scale, a characteristic of fractal objects. The slope of the line is related to the fractal dimension of the acini. The slopes are significantly higher for normal than abnormal livers (t = 4.04, df = 29, p = 0.005). On 32 liver scans with confirmed diagnoses, receiver operating characteristics (ROC) analysis was performed using power spectral slope as a feature. Analysis of the ROC curve yielded an area under the curve of 85, suggesting that power spectral slope may be a useful classifier of disease.
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Walker, Alan. "The carbon texture of metallurgical coke and its bearing on coke quality prediction." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/10950.
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The carbon in metallurgical coke is composed of textural units, varying in size and shape depending on the rank of coal carbonized. These induce a characteristic texture to coke surfaces. This thesis describes a study of the bearing of this texture on coke strength, particular emphasis being placed on investigating the feasibility of using textural composition data, determined by either scanning electron microscopy (SEX) of etched surfaces or polarized-light microscopy (PLX) of polished coke surfaces, as a basis of predicting the tensile strength of cokes produced from blended-coal charges from the behaviour of individual blend components. Scanning electron microscopy (SEM) of fractured coke surfaces revealed differences in the mode of fracture of textural components which implied variations in their contribution to coke strength. The tensile strengths of pilot-oven cokes, produced from blended-coal charges, could be related to their measured PLM textural compositions using equations derived from consideration of simple models of intergranular and transgranular fracture. The coke strengths could also be related, with greater precision, with textural data calculated from the coal blend composition and either the SEM or the PLM textural data for the cokes from the individual blend components. It was further found that the strength of blended-coal cokes were additively related to the blend composition and the tensile strengths of the single-coal cokes. Such relationships are useful, at the very least, for predicting the strength of cokes from other blends of the same coals carbonized under similar conditions. The various approaches to coke strength prediction have potential value in different situations.
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Conca, Karen Rose. "Ferulic acid and peroxidase infusion into disparate vegetables and its effect on texture /." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3115625.
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Munoz, Moran Placido. "The graffiti texture in Barcelona : an ethnography of public space and its surfaces." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/the-graffiti-texture-in-barcelona-an-ethnography-of-public-space-and-its-surfaces(0bcdd894-ceb2-4bc6-a922-94305771a106).html.
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Jaques Ranciére (2009b) argues that if there is a political question in contemporary art, ‘…it will be grasped through the analysis of the metamorphoses of the political ‘third’, the politics founded on the play of exchanges and displacements between the art world and that of non art’ (2009b:51). Looking at graffiti and street art in Barcelona as ‘textures’, which stimulate the mind, body and senses. I have investigated what public space means for its inhabitants through the material nature of the surfaces by which it is contained and by applying media devices. This has led me to develop an ethnography of encounters, perceptions and sensibilities linked to political practices and different modes of participation in the everyday life of the city. Following Jacques Ranciére’s (2004) conception of ‘political aesthetics’, I argue that the aesthetic of graffiti and street art can be embodied according to different sensible orders in the city. The public space is key in this process and I see it as an interface between graffiti artists, the general public and the institutions of the city. Graffiti activate the urban landscape through visual and tactile transformations of space through surfaces. These interactions, as De Certeau (1985) claims about everyday practices, may articulate narratives, which became the main source of information for this thesis. Thinking about the graffiti works in Barcelona in terms of Bakhtin’s (1981) idea of ‘the chronotope’, I have recounted the stories, which make the transformation of public space indicative of the everyday life of the city applying practices of collaboration, dialogue and intervention. These practices connected me to different surfaces of the city so as to explore how their material qualities are permeated with social relations and artistically inscribed with historical and political meanings. Here, graffiti and the city formed a compound of images in which I have studied the ‘visuality’ of graffiti in Barcelona. This, as Hal Foster (1988) argues, encloses at the same time social facts and physical operations (body and psyche) and moves, as I will show throughout this thesis, between dominant and resistance cultures. In short, I have materialized these ideas and images in the graffiti texture of Barcelona, seeing it as a mutable surface, which mediates between different ways of seeing and living in this city.
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Meehan, Sarah. "Amyloid fibril formation by lens crystallin proteins and its implications for cataract formation." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616246.
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Zghal, Mohamed Chokri. "The relationship between bread physical texture and its structure determined by digital image analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0012/MQ51824.pdf.
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Parker, Charlotte Clair. "The (bio)chemistry of cell adhesion in edible plant tissues : its role in texture." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327534.
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Lust, Sandra. "Etude de la formation du silicium macroporeux de type p et application aux cellules solaires au silicium multicristallin." Paris 11, 2002. http://www.theses.fr/2002PA112215.
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Le but principal de cette thèse a été d'appliquer la formation des macropores comme méthode de texturisation du silicium (Si) multicristallin pour les cellules solaires. Pour cela, nous avons d'abord étudié les conditions de formation des macropores à la surface du Si monocristallin (Si-c) de type p de résistivité 0. 2 à 2 w. Cm, qui est celle utilisée dans la fabrication industrielle des cellules solaires. Nous avons montré que les macropores ne sont formés sur ses substrats qu'en présence de HF dans des solvants organiques spécifiques. Pour obtenir plus d'informations sur le mécanisme de la dissolution, nous avons étudié l'interface pendant la dissolution du Si à l'aide de la phototension de surface et de la photoluminescence. Les mesures de photoluminescence montrent que la surface du Si est bien passivée dans le régime de formation du Si poreux. Ainsi, les espèces intermédiaires formées pendant la dissolution du Si sont plutôt de nature ionique que sous forme de liaisons pendantes. Les mesures de phototension montrent qu'au potentiel de repos et sous polarisation anodique, le Si est en régime d'appauvrissement. Nous avons appliqué les conditions optimisées de formation du Si macroporeux au Si multicristallin (Si-mc). Les surface ainsi obtenues possèdent une réflectivité effective très basse (~ 10%). Des cellules solaires à base de Si-mc Polix texturisé macroporeux ont été fabriquées avec le processus industriel standard de Photowatt. Elles présentent une augmentation du rendement de conversion solaire (13. 3% à comparer au 12. 5% de rendement moyen des cellules de références polies). Le rendement quantique interne de la cellule texturisée macroporeuse est meilleur aux grandes longueurs d'ondes que celui de la cellule référence, probablement à cause d'un effet de piégeage de la lumièreThe principal goal of this work consisted in the formation of macropores on the surface of multicrystalline silicon with a resistivity between 0. 2 and 2 w. Cm, which is used in the fabrication of solar cells. First, we studied the conditions of formation of macropores on monocrystalline p-type silicon of the same resistivity. We found that macropores can only be formed when electrolytes containing mixtures of HF with specific organic solvents were used. In order to gain information about the dissolution mechanism, in-situ measurements of surface photovoltage and photoluminescence at the silicon/electrolyte interface were performed during the dissolution. The photo- luminescence shows that the surface is well passivated in the region of porous silicon formation. From the measurement of the photovoltage at the rest potential and under anodization, it can be concluded that the silicon is depleted. The conditions for macropore formation were optimized and applied to the Polix multicrystalline silicon. The resulting surfaces exhibit a very low reflectivity (~ 10%). Next, macroporous texturized solar cells were made by the industrial standard processing of Photowatt. The solar cells show an increased efficiency (13. 3% compared to 12. 5% cell average efficiency of the polished reference cells). The internal quantum efficiency of the macroporous texturized silicon solar cells is increased at long wavelength compared to the reference cells, probably due to light trapping
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ORLIONNET-RESZETKO, VERONIQUE. "Possibilites de formation de la texture de goss dans des materiaux fesi elabores par solidification rapide*." Paris 6, 1991. http://www.theses.fr/1991PA066708.
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Nous avons etudie les possibilites de formation de la texture de goss sur des rubans de fesi elabores par flot planaire et par trempe entre cyclindres. Les echantillons possedent une microstructure de solidification telle que leur texture est du type 100
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Tingle, Malcolm Drummond. "Hapten-protein conjugate formation and its immunological consequences." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235549.
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Ateba, Betanda Yanick Blaise Olivier. "Formation de la l'hypertexture Cube {100}<001> dans les alliages cubiques à faces centrées." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS001.
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Les substrats métalliques ont été élaborés par des traitements thermomécaniques (laminages et recuits)sur des alliages Fe48%Ni et Ni5%W dans le but d'obtenir une hypertexture Cube indispensable à l'épitaxie de l'YBaCuO et du silicium dans la fabrication des câbles supraconducteurs et des cellules photovoltaïques à couches minces. Le rôle des éléments d'alliages tels que le soufre et le niobium sur la recristallisation et la formation de l'hypertexture Cube a été étudié dans le Fe48%Ni. Il a été montré que l'ajout du soufre favorise le développement de la texture Cube alors que l'ajout du niobium empêche la formation de la texture Cube. Le soufre se combine avec le Mn pour former les précipités MnS qui contribuent à l'augmentation de la différence d'énergie stockée entre l'orientation Cube et les orientations de laminage à froid (ECube/autres) quand le soufre augmente. Ce gap d'énergie explique explique l'acuité de la texture Cube avec l'ajout du soufre. Contrairement au soufre, l'ajout du niobium empêche la formation de la texture Cube, ce résultat s'explique par le fait la différence d'énergie stockée entre l'orientation Cube et les orientations de laminage diminue avec l'ajout du niobium. Pour expliques tous ces résultats, les analyses de microstructures et textures ont été faites par la technique EBSD et l'énergie stockée a été estimée à partir de la diffraction des neutrons sur les états déformésSubstrate tapes were prepared by cold rolling and annealing of a Fe48%Ni and Ni5%W alloys in order to obtain Sharp Cube {100}<001> oriented substrate for photovoltaic thin films and superconductor cables in particular.The effect of microalloying elements sulfur and niobium on recrystallization and sharp Cube formation was studied in Fe48%Ni. It was shown that the addition of sulfur promotes the formation of Cube grains while the addition of niobium prevents the Cube grains formation. Regarding sulfur, it combines with manganese to form the MnS precipitates wich increases the stored energy difference between Cube component and others cold rolled components ECube/other when sulfur is added. This stored energy difference explains the sharpness of the Cube texture when sulfur is added. On the contrary the niobium microalloying element addition prevents the formation of Cube grains. This could be explained by the fact that stored energy of cold-rolled components decreases with the addition of niobium and thus decreases Cube grains fraction when niobium is added. In order to explain these results, the development of Cube texture during recrystallization has been investigated in detail by EBSD, furthermore, the effect of stored energy has been studied by carrying out neutron diffraction measurements on the deformed states
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Iwagoshi, Thawi. "Influence of oxygen partial pressure on the crystal growth and texture formation of some high-tc superconductors /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu148794150429637.
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Jain, Sanjay. "The process of standard formation and its strategic implications." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187373.
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This dissertation is motivated by the recent increase in formation of product standards in many high technology markets. These markets are characterized by a high degree of technological uncertainty and high levels of R&D expenditures by incumbent firms. In this dissertation we examine how how rapid technological change in the environment affects firms incentive to standardize. We also examine how product standards affect R&D investment levels and how firms' competence in different types of innovation affects their preferences for compatibility. We developed a game theoretical model in which firms make both compatibility and R&D investment decisions. We first studied how rapid technological change in high technology markets affects firms' incentive to standardize. We find that the inherent technological uncertainty in high technology environments promotes the formation of standards. This result is in contrast to the popular view that in technologically uncertain environments standards are less likely to be formed. Our results suggest that incumbent firms can use standards to protect themselves from the threat of displacement by exogenously developed superior technology. In other words, incumbent firms can use compatibility as a competitive tool to deter entry. We also find that compatibility generally leads to higher investments in minor R&D. In contrast, compatibility decreases investment in breakthrough R&D. This result suggests that standards affect the nature of R&D competition. Before products are standardized, firms are more likely to invest in developing new breakthrough technologies. In contrast, when products become standardized innovation efforts will be focused on developing minor improvements for the present technology. We also examined how firms' R&D competence will affect their preferences for compatibility. Our results show that firms which are more efficient at developing at minor product improvements have a stronger preference for compatibility than firms which are less efficient in minor R&D. In contract, firms which are efficient in developing breakthrough technologies find standardization a less attractive option.
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Percival, Will. "Cosmological structure formation and its link to quasar evolution." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325786.
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Sobral, David Ricardo Serrano. "Star-formation history of the universe and its drivers." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5732.
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Determining the cosmic star formation history of the Universe is fundamental for our understanding of galaxy formation and evolution. While surveys now suggest that the "epoch" of galaxy formation occurred more than 6 billion years ago, our measurements still suff er from signi ficant scatter and uncertainties due to the use of diff erent indicators, dust extinction and the e ffects of cosmic variance in the current samples. Furthermore, understanding galaxy formation and evolution require us to go much beyond simply determining the star formation history of the Universe with high accuracy: what are the physical mechanisms driving the strong evolution that we observe? How does star formation depend on stellar mass and environment and how does that change with cosmic time? This thesis presents both a completely self-consistent determination of the star formation history of the Universe (based on a single, sensitive and well-calibrated star formation indicator up to redshift z ~ 2:3: the H α luminosity) and investigates its drivers by exploring large area surveys (probing a range of environments and overcoming cosmic variance) obtained with the High-redshift Emission Line Survey (HiZELS). HiZELS is a panoramic extragalactic survey using the WFCAM instrument on the 3.8-m UK Infrared Telescope (UKIRT) which utilizes a set of existing and custom-made narrow-band filters in the J, H and K bands to detect emission line galaxies (main targets are H α emitters at z = 0:84, z = 1:47 and z = 2:23) up to z ~ 9 over square degree areas of extragalactic sky. Detailed measurements of the H α luminosity function and its evolution with redshift are presented, revealing a signi ficant luminosity evolution. The clustering properties of H α emitters at high-redshift are quantifi ed and investigated for the first time, revealing that these distant galaxies reside in Milky-Way type dark matter haloes at z ~ 1. Mass and environment are found to have important and inter-dependent roles on star formation at high-z and the results are able to reconcile previously contradictory results in the literature. Furthermore, by conducting a novel double-narrow band survey at z = 1:47, the relationship between the [Oii]3727 and H α emission lines is studied in detail and directly compared to z ~ 0, showing no signifi cant evolution in the dust properties of star-forming galaxies, despite the very strong luminosity evolution. Finally, this thesis also presents the widest search for very distant Ly α emitters at z ~ 9.
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Hur, YoungTeck. "Cavity formation and its remote sensing in sand layer." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/136150.
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Caicedo, Parra Dina Maria. "Mechanism to Quantify Road Surface Degradation and Its Impact on Rolling Resistance." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555430578466857.
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Gajula, Hyma. "Effect of wheat bran on gluten network formation as studied through dough development, dough rheology and bread microstructure." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35570.
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Doctor of PhilosophyDepartment of Grain Science and Industry
Hulya Dogan
Jon M. Faubion
The overall hypothesis underlying this study is that the nature and extent of bran interactions with the gluten protein matrix play a dominant role in both 'in-process' dough and final product quality of whole grain baked goods. Therefore, the purposeful manipulation of those interactions should be able to minimize adverse processing or product characteristics resulting from bran inclusion/presence. The approach we took was to study the effects of bran milled to different particle sizes on dough development during and after dough mixing using fundamental rheology combined with traditional cereal chemistry approaches and x-ray microtomography (XMT). The research outcomes were used to create a better picture of how the bran is effecting the dough development and to suggest strategies that allow for the control of that effect. Study-I focused on characterization of the chemical properties, empirical rheological properties and baking performance of flours and dough with different bran contents from different sources. The development of dough microstructure and the resulting crumb texture in the presence of different bran were studied using XMT. HRW and SW bran additions resulted in higher water absorptions (WA) irrespective of the flour type and bran source. Fine bran caused slightly higher WA followed by coarse and as is bran. Both HRW and SW bran decreased the dough stability of HRW flour, while it improved the stability of SW flour doughs. Macro and microstructure of baked products were significantly affected both bran type and addition level. HRW bran added to HRW flour resulted in 8-23% decrease in loaf volume while SW bran added at the same level caused 3-11% decrease. XMT indicated that bran decreased the total number of air cells significantly. SW flour resulted in harder crumb texture than that of HRW flour breads. Overall, SW bran had less detrimental effects on mixing and baking performance of HRW flour. Study-II focused on specific bran particle size and composition on small and large deformation behavior of strong and weak flour doughs. Small deformation behavior was characterized using frequency and temperature sweep tests, while the large deformation behavior was studied using creep–recovery and uniaxial extensional testing. The results revealed that the rheological behavior of bran-enriched doughs depend on type of base flour, bran type, bran replacement level (0, 5, 10%), and the dough development protocol. Weak flour doughs benefited from inclusion of bran as inherently low peak height and stability of these doughs improved in the presence of bran. Temperature sweeps indicated a slight decrease in Gʹ and G" until around 55-60°C. In the same temperature range, presence of bran increased the moduli of composite four compared to that of the control flours. Creep compliance parameters indicated that both bran source and bran replacement had significant effect on maximum compliance (J[subscript max]) and elastic compliance (J[subscript e]). Finally, the bran type affected uniaxial extensional properties, maximum resistance (R[subscript max]) and elasticity (E), significantly independent from the type of base flour.
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Young, Tanya. "The Bunyeroo Formation and its possible cold-water marine setting /." Title page and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09SB/09sby77.pdf.
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Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1996.National Grid reference Parachilna 1:250,000 Copley 1:250,000(SH54)9,13. Includes bibliographical references (leaves 42-50).
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DeFigueiredo, Tania Glacy do Brasil. "A new boundary element formation and its application in engineering." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278110.
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Delsaut, Maxence. "Methyl cation in astrochemistry: ab initio study of its formation." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209191.
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This thesis is dedicated to the theoretical study of the methyl cation CH3+ electronic states and, globally, falls within the study of the interstellar clouds molecular synthesis and the chemistry of the hydrocarbons which are present in high-energy plasmas such as in the experimental nuclear fusion reactor ITER. Among the different possible formation reactions, we chose two reactions involved in these fields: the ionization of the methyl radical CH3 ground state and the reactive collisions between simple carbonated or hydrocarbonated (C, CH+ and CH2+) and hydrogen species (H3+, H2 and H, respectively).As this cation is characterized by 8 electrons and 4 nuclei, this allowed us to perform high-level ab initio calculations using the CASSCF/MRCI method with the Dunning aug-cc-p(C)VXZ basis sets. These calculations were completed by a study of different methodological effects such as the core-valence electronic correlation, the complete basis set extrapolation and the basis set superposition error.
We calculated equilibrium geometries (precision within 10^-5 angtröm and 10^-2° and their energies for the methyl radical and cation, studied the potential energy surfaces involved by the Jahn-Teller effect targeting the methyl cation E' states and achieved frequencies calculations. From these values were derived ionization potentials (IP) from the methyl radical ground state towards the methyl cation lowest-lying states (precision within 10^-2 eV). Vibrational corrections and nuclear relaxation effects were taken into account.
The calculated IPs and frequencies should facilitate the analysis of methyl radical threshold photoelectron spectra leading to the methyl cation lowest-lying states, recorded at the synchrotron facility Soleil by the Dr. Alcaraz group from the Université Paris-Sud.
Through reaction paths calculations using a quadratic steepest-descent method, we have proposed new reactional pathways enabling the connections between the different dissociation channels correlated to the cation lowest-lying triplet states. The absence of potential barriers in the energy profiles allows us to propose these reactions as sources, in interstellar clouds, of hydrocarbonated molecules whose stability increases with growing size according to the series C -> CH+ -> CH2+ -> CH3+.
The groups of Pr. Urbain from UCL and Dr. Savin from Columbia University studied the collisions in copropagating beams of C and H3+ leading to the formation of these hydrocarbonated species. The proposed reactional mechanisms are in good agreement with the experimental observations, what permits a better understanding of the chemistry behind these collisional processes of astrochemical interest.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Resco, de Dios Víctor. "Patterns of savanna formation in former semiarid grasslands the interactive role of climate change, soil texture and neighbor identity /." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1800189201&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Nciizah, Adornis Dakarai. "Aggregate stability, crust formation, steady state infiltration and mode of seedling emergence in soils with various texture and mineralogy." Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1015539.
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The general objective of this study was to quantify the interactive effects of soil texture and mineralogy on soil crusting, infiltration and erosion and the subsequent effects on maize seedling emergence and early development using soils collected from 14 ecotopes in the Eastern Cape Province. The specific objectives were to determine; i) particulate organic matter, soil texture and mineralogy relations, ii) aggregate stability and breakdown mechanisms as affected by soil texture and organic matter, iii) crust formation and steady state infiltration, iv) rainfall pattern effects on crusting, infiltration and erodibility and v) rainfall intensity effects on crusting and mode of seedling emergence. Particulate organic matter (POM) was fractionated into litter POM, coarse POM and fine POM. Both total soil organic matter (SOM) and the POM in each fraction were determined using the weight loss on ignition procedure. Most ecotopes were either sandy loam or sandy clay loam and primary minerals especially quartz dominated the soil mineralogy. The clay content was significantly related to the total SOM (r = 0.78), hematite (r = 0.83) and quartz (r = -0.74). Aggregate stability was determined following methods described by Le Bissonnais (1996) i.e. fast wetting (FW), slow wetting (SW) and wet stirring (WSt). Aggregate breakdown followed the order; slaking < mechanical breakdown < micro-cracking for most ecotopes except Lujiko Leeufontein and Amatola Jozini where SW and WSt resulted in the least MWD respectively. Aggregate stability was significantly correlated to POM only for FW and SW and only positive but not significant for WSt. To study crust formation, aggregate sizes <2, 2 to 3, 3 to 5 mm were exposed to 60 mm hr-1 simulated rainfall. Sieving structural crusts, ~0.2 to ~0.8 mm thick with a surface layer of loose grains overlying a thin plasmic layer, formed in all ecotopes. Crusts with strengths between 0.25 and 3.42 10-4 kg m-2 developed on the <2 mm compared to <2.23 10-4 kg m-2 in the >2 mm aggregates. The reverse occurred in Alice Jozini, which had relatively low clay content of 120 g kg-1. Two significantly different groups of the SSIR were observed. The SSIR was between 1.24 and 3.60 mm hr-1 in the group of ecotopes dominated by primary minerals and relatively lower clay content. In the second group, consisting one ecotope dominated by kaolinite and relatively higher clay content, the SSIR was 15.23 mm hr-1. Rainfall pattern i.e. rainfall applied either as an eight minute single rainstorm (SR) or four-two minute intermittent rainstorms (IR) separated by a 48 h drying period significantly (p < 0.05) affected crust strength, SSIR and erosion. The IR resulted in higher crust strength and SSIR than SR. The effect of rainfall pattern on SSIR was mostly influenced by the primary minerals namely, quartz. Three maize seeds of equal size were planted in plastic pots, pre-wetted by capillary action and then subjected to simulated rainfall at three intensities for 5 min. Rainfall intensity (30, 45 and 60 mm h-1) significantly (P < 0.05) affected crust strength and mean emergence day (MED) but not emergence percentage (EMP) and shoot length (P > 0.05). The 60 mm h-1 rainfall intensity resulted in the highest crust strength and MED.
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Sato, Akihiko. "Statistical genetic analysis of berry flesh texture and breeding strategies for its improvement in interspecific hybrid grapes." Kyoto University, 2006. http://hdl.handle.net/2433/144077.
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Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第11839号
論農博第2593号
新制||農||928(附属図書館)
学位論文||H18||N4151(農学部図書室)
24381
UT51-2006-J536
(主査)教授 米森 敬三, 教授 矢澤 進, 教授 谷坂 隆俊
学位規則第4条第2項該当
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James, S. D. "Volcanism in sedimentary basins and its implications for mineralization." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379244.
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Bejaoui, Syriac. "Etude de la formation de la glace au sein de la texture poreuse des matériaux à base de liant hydraulique." Toulouse, INSA, 2001. http://www.theses.fr/2001ISAT0015.
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Les travaux concernent la problématique de la gestion des déchets radioactifs, et visent à contribuer à une meilleure prédiction de la tenue au gel des bétons. Les conditions de formation de la glace au sein de la texture poreuse des pâtes de ciment et des bétons ont été étudiées selon la technique d'analyse calorimétrique différentielle et un modèle thermodynamique. Il est montré que les basses températures de formation de la glace au sein des pores ne sont dues qu'en partie à la surfusion de la solution interstitielle induite par les restrictions de taille des cristaux, la présence d'éléments chimiques dissous, et les pressions de confinement. En revanche, en considérant la théorie de la germination et le degré de division de la texture poreuse, trois mécanismes de formation de la glace peuvent être définis, au voisinage de -10, -25 et -40ʿC. Ces résultats permettent d'expliquer les différences de comportement au gel entre les matériaux à base de ciment CPA-CEMI et ceux à base de ciment CLC-CEMV, ainsi que, probablement, entre certains BHP, et laissent envisager l'application de la calorimétrie différentielle comme un outil de test de la tenue au gel des bétons. Par ailleurs, cette étude met en évidence un retrait irréversible des pâtes de ciment et des bétons induit par les cycles de gel /dégel sans apport d'eau, et, sur la base de mesures de diffusion de neutrons aux petits angles, la présence d'une texture poreuse de type surface fractale au sein des pâtes de ciment à hautes performancesThis work concerns the nuclear waste management problematics, and aims at contributing to a better prediction of concrete freeze / thaw behaviour. Ice formation in the porosity of cement pastes and concrete was studied using differential scanning calorimetry and a thermodynamic model. It is shown that ice formation low temperatures in the pores can't be explained considering only interstitial solution undercooling induced by crystal size restrictions, dissolved chemical elements, and containment pressures. On the other hand, taking into account the nucleation theory and the porosity division degree, three ice formation mechanisms can be defined, near -10, -25 et -40ʿC. These results allow to explain freeze / thaw behaviour differences between blended and portland cement based materials, as well as, probably, between some high performance concrete, and allow to consider using differential scanning calorimetry as a tool for testing concrete freeze / thaw behaviour. In addition, this study highlights an irreversible shrinkage for cement pastes and concrete induced by freeze / thaw cycles without provision of water, and, on the basis of small angle neutrons scattering measures, the presence of a fractal surface type porosity in high performance cement pastes
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Hussin, Zarina Mohd. "An on-line optical based system approach for surface texture/topography inspection and its implementation and application perspectives." Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436597.
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Perrett, Kathryn. "The globular cluster system of M31, keys to its formation history." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ63443.pdf.
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Dombowsky, Don. "Nietzsche's plan for political organization and its formation in political theory." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ66144.pdf.
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Davies, Sian Patricia Mary. "7,8-Dihydroneopterin and its effect on the formation of foam cells." Thesis, University of Canterbury. School of Biological Sciences, 2015. http://hdl.handle.net/10092/10908.
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Atherosclerosis (Heart Disease) is an inflammatory disease caused by the formation of plaque within the arterial wall. In response to inflammation, monocytes enter the artery wall, differentiate into macrophages and take up altered low-density-lipoprotein (such as oxidised-LDL). This oxLDL is taken up into the phagocytotic macrophages via the action of the scavenger receptors. If more oxLDL is engulfed than the cell can process, they further differentiate into lipid-loaded foam cells. These are the main cell type found in atherosclerotic plaques. The scavenger receptor CD36 is responsible for 70% of oxLDL uptake by macrophages. Previous studies show that CD36 expression can be down regulated by the antioxidant, 7,8-dihydroneopterin. This research focuses on the effect of CD36 down regulation by 7,8-dihydroneopterin on foam cell formation.
Human macrophages prepared from monocytes purified from human blood were incubated with copper oxidised LDL for up to 48 hours. Macrophage accumulation of the sterols was measured using a high performance chromatograph (HPLC) method developed as part of this project. The HPLC analysis measured: cholesterol, cholesteryl-oleate and -palmitate and 7-ketocholesterol accumulation within human macrophages. A flow cytometry procedure was developed where the strongly adherent macrophages could be lifted from the tissue culture plates before immuno staining for CD36. Effect of incubating macrophages with 7,8-dihydroneopterin on the formation of foam cells was studied by measuring the lipid content by HPLC and flow cytometry measurement of CD36.
HPLC analysis showed non-cytotoxic levels of oxLDL produced a large accumulation of cholesterol and cholesteryl esters in the macrophages. Cholesterol, 7-ketocholesterol and cholesteryl-oleate and -palmitate concentrations in the cells rose significantly over the first 24 hours and stayed at a steady level for the following 24 hours. CD36 levels was further analysed on human macrophages. This study shows that foam cell formation can be measured using human macrophages. 7,8-Dihydroneopterin treatment resulted in a reduction of cholesterol and oxysterol uptake back to basal levels. It also reduced CD36 cell surface expression by a third. These results suggest that even a small reduction in CD36 cell surface expression may have a large effect on foam cell formation. This is another mechanism by which 7,8-dihydroneopterin protects against atherosclerosis developing.
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Kakavoulia, Maria. "Interior monologue and its discursive formation in Melpo Axioti's Dyskoles nychtes." München : Institut für Byzantinistik und Neugriechische Philologie der Universität, 1992. http://books.google.com/books?id=N2ZiAAAAMAAJ.
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Li, Sheng-han. "Organic-metal interface formation and its applications in organic electronic devices." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1667991421&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Kakavoulia, Maria. "Interior monologue and its discursive formation in Melpo Axioti's "Duskoles nuhtes" /." München : Institut für Byzantinistik und neugriechische Philologie der Universität, 1992. http://catalogue.bnf.fr/ark:/12148/cb357139538.
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OLIVEIRA, FABIOLA STAPPAZZOLI DE. "A TRADITIONAL UNIVERSITY, FAMOUS FOR ITS RESEARCH, DEALING WITH TEACHERS FORMATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5198@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste estudo objetivou apreender como uma universidade tradicionalmente reconhecida pela pesquisa, a PUC-Rio, vem reagindo às novas resoluções estabelecidas pelo MEC, que recomendam especialmente o aumento de horas destinado à prática nos cursos de licenciatura, correspondendo esta a diversas atividades a serem realizadas ao longo de toda a formação e perpassando todas as disciplinas. Para isso, foram observados encontros que buscam discutir as sugestões da lei e entrevistados os professores de Prática de Ensino e os coordenadores desses cursos. Verificou-se grande dificuldade em compreender o novo significado atribuído à prática, principalmente em virtude da necessidade de reflexão e discussão em sala de aula de como o conteúdo específico que vem sendo trabalhado pode e deve ser tratado nas escolas. Também foram questionados a provável perda da formação teórica desses alunos e o tempo de duração do curso, que deve agora apresentar currículo próprio, ou seja, distinto do Bacharelado. Isso muito se deve à desvalorização das questões de ensino no ambiente acadêmico, mas, igualmente, à falta de vivência desses profissionais no ensino básico. Nesse sentido, ao mesmo tempo em que se assinalou a necessidade de revisão e criação de disciplinas para a adaptação às recomendações da legislação, foi salientada a importância de ajuda financeira do Estado e de formação de um núcleo de formação de professores na instituição, que possa reunir formadores interessados pela temática a fim de reestruturar adequadamente as licenciaturas. Os depoimentos apontam que ainda é preciso tempo para que os professores e a própria universidade tenham claro para si como deve um curso de licenciatura estar estruturado e organizado para de fato formar um professor.
The purpose of this study is to understand how a traditional university, famous for its research, PUC-Rio, has been dealing with the new MEC indications, that recommend as a main point the increase of time designated to the practice in the licenciatura courses. This new concept of practice relates to many different activities that were not considered before, and should be introduced into the whole course and in all subjects. To collect the necessary information, meetings, where the application of the new indications has been discussed, were observed, and coordinators and Prática de Ensino professors were interviewed. It was identified a considerable difficulty to understand the new meaning of practice, specially because of the reflection and necessity of discussion at classroom about how the specific contents that have been studied should and may be treated at school. The probably loose of theoretical base and the duration of the course were also questioned. The devaluation of educational issues at the academic environment and the lack of experience of those professionals at school contribute to explain these problems. In this study, it was figured out not only the need of subjects creation and review, but also the need of financial government support and the development of a new group of educational studies, in which interested professors in that theme can join and point out ways to improve it. This research evidence that both, professors and the university itself, require more time to clarify how a licenciatura course should be structured and organized.