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Anti-Poverty Policy as the Cultivation of Market Subjects: The Case of the Conditional Cash Transfer Program OportunidadesCannon, Kailey L. January 2014 (has links)
My thesis explores the conceptual underpinnings of the acclaimed Mexican conditional cash transfer (CCT) program Oportunidades as a way of engaging broader debates about how anti-poverty policy is evolving in the wake of the World Bank’s mid-1990s legitimacy crisis. I am interested in the behaviours and attitudes—or “subjectivities”—that Oportunidades attempts to cultivate amongst participants. Whereas the majority of CCT studies tend to focus on measuring the extent to which the programs “mold” beneficiaries into the categories of being prescribed by the program, my thesis is concerned with specifying and critically examining these categories. I use a hybrid neo-Gramscian, governmentality and critical feminist theoretical framework to probe how Oportunidades beneficiaries are constructed within World Bank and Mexican government discourse, as well as in external program evaluations. I argue that Oportunidades is underpinned by an agent-centred conception of poverty and that the program promotes a kind of gendered market-conducive subjectivity amongst beneficiaries. I conclude by exploring some of the implications of the CCT model.
Ma thèse explore les fondements conceptuels du Oportunidades, un programme de transferts conditionnels de fonds (TMC) Mexicain acclamé. J’utilise les TMC comme une ouverture pour élargir le débat sur la manière dont la politique anti-pauvreté évolue dans le sillage de la crise de légitimité à laquelle la Banque Mondiale a fait face dans le milieu des années 1990. Je m'intéresse aux types de comportements et d'attitudes—ou «subjectivités»—que Oportunidades essaye de cultiver chez les participants. Alors que la majorité des études sur les TMC focalisent sur l’évaluation des succès du programme à modeler les participants afin qu’ils entrent dans les catégories de personnes prescrites par le programme, mon but est la spécification et l'examen critique de ces catégories. J'utilise un cadre théorique hybride qui combine néo-gramsciennes, la gouvernementalité et des théories féministes critiques pour enquêter sur la façon dont les bénéficiaires du programme Oportunidades sont construits à l’intérieur du discours de la Banque Mondiale, du gouvernement mexicain, ainsi que dans les évaluations externes du programme. Je soutiens qu’il y a, dans le programme Oportunidades, une conception sous-entendu de la pauvreté centrée sur les comportements des individus et que le programme promeut une subjectivité sexuée des bénéficiaires qui facilite leur participation au marché. Je conclus en explorant quelques implications du modèle TMC.
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The Mechanism of Assembly of the G-Protein Beta Gamma Subunit Dimer by CK2 Phosphorylated Phosducin-Like Protein and the Chaperonin Containing TCP-1Baker, Christine M. 14 June 2006 (has links) (PDF)
Phosducin-like protein (PhLP) binds G-protein beta gamma subunits and is thought to assist in assembly of the G-protein beta gamma dimer. Phosphorylation of PhLP at serine residues 18-20 by the casein kinase 2 (CK2) appears to play an essential role in this process. PhLP has also been shown to interact with the chaperonin containing TCP-1 (CCT) atop its apical domain, not entering the substrate folding cavity. However, the physiological role of the PhLP-CCT interaction in G-protein beta gamma dimer formation remains unclear. This study addresses the mechanism of G-protein beta gamma assembly by exploring the specific roles of CCT and CK2 phosphorylation of PhLP in the assembly process. Both overexpressed and endogenous Gbeta were shown to co-immunoprecipitate with CCT to a similar extent as PhLP, indicating that CCT may be involved in the folding of Gbeta. In addition, Ggamma overexpression enhanced the binding of PhLP to CCT, suggesting the formation of a ternary PhLP-Gbeta-CCT complex. In contrast, overexpression of PhLP caused the release of G-beta from CCT. This release was blocked by a PhLP S18-20A variant that lacks the S18-20 CK2 phosphorylation site. PhLP S18-20A has been previously shown to negatively affect the G-protein beta gamma dimer formation, suggesting a correlation between PhLP-mediated release of Gbeta from CCT and G protein beta gamma assembly. Experiments investigating the role of Ggamma in this process show that Ggamma does not interact with CCT nor is it the essential factor in the release of Gbeta from CCT. A new model is therefore proposed for the G-protein beta gamma subunits' assembly involving the formation of a PhLP-Gbeta-CCT ternary complex followed by the release of a phosphorylated PhLP-Gbeta complex from CCT. In the PhLP-Gbeta complex, the Ggamma binding face of Gbeta is exposed, allowing for the formation of the G-protein beta gamma dimer.
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Feasibility of Manipulating Correlated Color Temperatures with a Phosphor Converted High-Powered Light Emitting Diode White Light SourceLittle, Matthew Michael 01 June 2010 (has links) (PDF)
In this thesis we examine the feasibility of developing a white light source capable of producing colors between 2500 and 7500 Kelvin on the black-body radiator spectrum by simply adjusting amperage to a blue and ultraviolet (UV) light emitting diode (LED). The purpose of a lighting source of this nature is to better replicate daylight inside a building at a given time of day. This study analyzes the proposed light source using a 385 nm UV LED, a 457 nm blue LED, a 479 nm blue LED, a 562 nm peak cerium doped yttrium aluminum garnet (YAG:Ce) phosphor, and a 647 nm peak selenium doped zinc sulfide (ZnS:Se) phosphor.
Our approach to this study initially examined optical performance of yellow-emitting phosphor (YAG:Ce) positioned at specific distances above a blue LED using polydimethylsiloxane (PDMS) as a substrate. An understanding of how phosphor concentration within the PDMS, the thickness of the PDMS, and how substrate distance from the LED die affected light intensity and color values (determined quantitatively by utilizing the 1931 CIE 2° Standard Observer) enabled equations to be developed for various lens designs to efficiently produce white light using a 457 nm peak wavelength LED. The combination of two luminescent sources (457 nm LED and YAG:Ce) provided a linear trend on the 1931 CIE diagram which required a red illumination source to obtain Kelvin values from 2500 to 7500. Red-emitting phosphor (ZnS:Se), selected to compliment the system, was dispersed with YAG:Ce throughout PDMS where they were stimulated with a blue LED thereby enabling all desired Kelvin values with differing concentration lenses. Stimulating ZnS:Se with the addition of a UV LED did not provide the ability to change the color value of the set up to the degree required. Many other factors resulted in the decision to remove the UV LED contribution from the multi-Kelvin light source design. The final design incorporated a combination of ZnS:Se and YAG:Ce stimulated with a blue LED to obtain a 2500 Kelvin value. A separate blue LED provides the means to obtain 7500 Kelvin light and the other color values in between, with a linear approximation, by adjusting the amperages of both LEDs.
In addition to investigating the feasibility of obtaining the Kelvin values from 2500 to 7500, this thesis also examined the problem of ZnS:Se’s inability to cure in PDMS and a method to create a lens shape to provide equal color values at all points above a phosphor converted LED source. ZnS:Se was found to be curable in PDMS if first coated with a low viscosity silicon oil prior to dispersion within PDMS. The lens configuration consists of phosphors equally distributed in PDMS and cured in the shape of a Gaussian distribution unique to multiple factors in LED-based white light design.
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Optimization Studies to Improve MSC-based Cardiac Cell Therapy : Cytokine Preconditioning and Nanoparticle CouplingZhou, Wanjiang 12 1900 (has links)
Contexte: La cardiopathie ischémique (IHD) reste une cause majeure de mortalité en Amérique du Nord. La thérapie cellulaire cardiaque (CCT) a émergé comme une thérapie prometteuse pour aider à guérir certaines malades cardiaques. Parmi les cellulaires avec propriétés pluripotentes, les cellules stromales mésenchymateuses (MSC) sont prometteuses. Cependant, plusieurs questions demeurent non résolues et certaines défis empêchent l'application clinique de la CCT se dans l'IHD, tels que le faible taux de rétention cellulaire in situ, le suivi des cellules in vivo post-implantation et post-acheminements et l`apoptose. Ici, le traitement préliminaire des MSC avec des facteurs de croissance et leur couplage avec des nanoparticules (NP) seront étudiés comme des méthodes pour optimiser MSC. Méthodes: Des MSCs provenant du rat (rMSC) et du cochon (pMSC) ont été isolés à partir de moelle osseuse. Les rMSC ont été préconditionnées avec SDF-1a, TSG-6 et PDGF-BB, et ensuite soumises à une hypoxie, une privation de sérum et a un stress oxydatif. Des études de cicatrisation ont également été effectués avec rMSCs préconditionnées. En parallèle, de nouvelles NP ferromagnétiques liées aux silicones ont été synthétisées. Les NPs ont été couplées aux pMSCs suivant leur fonctionnalisation avec l`anticorps, CD44, un antigène de surface du MSC bien connu. Par la suite, les études de biocompatibilité ont été réalisées sur pMSC-NP et en incluant des tests des processus cellulaires tels que la migration, l'adhésion, la prolifération et les propriétés de la différenciation. Résultats: Parmi toutes les cytokines testées, PDGF-BB a démontré la plus grande capacité à améliorer la survie de MSC dans des conditions d'hypoxie, de privation de sérum et en reponse au stress oxydatif. La conjugaison de NP a atténué la migration et la prolifération des pMSCs, mais n`a pas changé leur capacité de différenciation. Enfin, la complexe du MSC-NP est détectable par IRM. Conclusion: Nos données suggèrent que de nouvelles stratégies, telles que traitement préliminaire de PDGF-BB et le couplage des nanoparticules ferromagnétiques, peuvent être considérés comme des avenues prometteuse pour optimiser les MSCs pour la CCT. / Background: Ischemic heart disease (IHD) remains a leading cause of mortality in North America. Cardiac cell therapy (CCT) has emerged as a promising therapy to help heal the damaged heart. Among the various candidates for stem-progenitor cells, Mesenchymal Multipotential Stromal/Stem Cells (MSC) is of great promise. However, there remain unresolved issues and challenges that prevent clinical application of MSC-based CCT in IHD. Among the latter, low cellular retention rate, in vivo cell tracking and post-delivery apoptosis. Here in, growth factor preconditioning and MSC coupling to nanoparticles are investigated as methods to optimize MSC. Methods:Lewis Rat MSC (rMSC) and pig MSC (pMSC) were isolated from bone marrow. Rat MSCs were preconditioned with SDF-1a, TSG-6 and PDGF-BB, and then subjected to hypoxia, serum deprivation and oxidative stress. Wound healing assays were also done with preconditioned rat MSCs. In parallel, novel ferromagnetic silicone core-shell nanoparticles (NP) were synthesized. Pig MSCs were coupled to NPs following functionalization of the NPs with an antibody to a well-recognized MSC surface antigen, CD44. Subsequently, biocompatibility studies were performed on the pMSC-NP complex and included testing of key cellular processes such as migration, adhesion, proliferation and differentiation properties. Results: Of all cytokines used, PDGF-BB showed greatest capacity to improve MSC survival under conditions of hypoxia, serum deprivation and oxidative stress. NP conjugation has mitigated effect on the migration and proliferation of pig MSC, but do not change the differentiation capacity of MSC. Finally, the MSC-NP complex was detectable by MRI. Conclusion: Our data suggest that novel strategies, such as PDGF-BB preconditioning and ferromagnetic nanoparticle coupling, can be considered as promising avenues to optimize MSCs for CCT.
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SOCIAL MEDIA AS THE VEHICLE FOR BRAND AUTHENTICITY – THE CASE OF STREETWEAR FASHIONAbouradi, Omar Mokbel, Adam, Ahmed January 2024 (has links)
Background: In the digital era, the streetwear fashion industry has undergone significanttransformation due to the rise of social media. Traditional marketing methods have shiftedtowards direct consumer engagement through digital platforms, where brand authenticity andexclusivity are crucial for maintaining perceived value and consumer loyalty. Streetwearfashion, rooted in urban subcultures, relies heavily on these elements to establish and maintainits brand identity.Purpose: This thesis aims to critically examine how streetwear fashion brands utilize socialmedia to manage the authenticity paradox while driving exclusivity. It investigates the impactof these strategies on consumer behavior and brand loyalty within digital spaces.Method: The research employs a qualitative, exploratory design within an interpretivistparadigm. Data was collected through semi-structured interviews with a purposive sample of12 participants, including influencers, brand managers, and consumers actively engaged withstreetwear brands on social media. Thematic analysis was used to identify key patterns andinsights from the data.Conclusion: The findings reveal that streetwear brands effectively use social media to projectauthenticity through transparent communication and cultural engagement, while strategicexclusivity is maintained through limited releases and exclusive collaborations. Thesestrategies not only enhance perceived brand value but also foster strong community ties andconsumer loyalty. The study highlights the importance of balancing authenticity withexclusivity to navigate the competitive digital landscape and sustain brand appeal
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Social development through efficient policies, evaluating the impact of Bolsa FamiliaGoffeng-Nielsen, Per 12 1900 (has links)
Thesis (MA)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: The Brazilian welfare state has developed over time in relation to national and global trends. This study analyses the creation of Latin Americas largest Conditional Cash Transfer program in relation to these trends. The thesis provides an historical overview of the creation of Conditional Cash Transfers in the country that lastly ended with Bolsa Familia. Alongside events that led to Bolsa Familia, the nation witnessed the development of social welfare initiatives as well as alternative poverty reducing programs. The study analyses this in the context of the creation of the Brazilian welfare.
The question guiding the study is: Has the Bolsa Famila programme helped to reduce poverty in Brazil? It is argued that Brazil has been successful in reducing its poverty rate as a result of the programme. The study looks deeper into the structure of Bolsa Familia in order to view its results and effects both advantages and disadvantages of the programme are assessed. / AFRIKAANSE OPSOMMING: Die Brasiliaanse welvaart staat het in verhouding tot nasionale en internasionale tendense ontwikkel. Hierdie studie analiseer hoe Latyns-Amerika se grootste voorwaardelike kontant oordrag program in die lig van hierdie tendense ontwikkel het. Die tesis verskaf ‘n historiese oorsig tot die inwerkingstelling van voorwaardelike kontant oordrag programme en die wyse waarop dit meer spesifiek uitgeloop het op die Bolsa Familia program.
Die studie is gelei deur die vraag: Het die Bolsa Familia program daartoe bygedra dat armoede in Brasilïe verminder het? Benewens die feit dat hierdie vraag positief beantwoord word, bekyk die studie in groter detail die struktuur van die program asook die program se voordele en nadele.
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Multi-detector registration system for the study of multi-body decay of heavy body nucleiMalaza, Vusi David 12 1900 (has links)
Thesis (MMil)--Stellenbosch University, 2012. / Includes bibliography / Nuclear ssion is commonly known as a process where a heavy nucleus such as Uranium
or Thorium decays into two fragments of roughly equal mass. On occasion however, instead
of decay into two parts a process known as binary ssion, the nucleus can decay
into three fragments. In this decay channel known as ternary ssion, the nucleus splits
into three fragments with the third particle being too light compared to the main ssion
fragments. There are also instances where heavy nuclei split into three fragments of comparable
masses, the so called \true ternary ssion" as was predicted by the theoretical
calculations of Strutinsky [Str63]. While theoretical predictions hold promises for this decay
mode, experimental attempts had little success in proving the existence of true ternary
ssion in low energy ssion. The challenges and di culties faced by experimentalist in
con rming the existence of true ternary ssion also proved that this ssion mode is a very
rare phenomenon.
This thesis is devoted to the investigation of ternary ssion know as collinear cluster tripartition
(CCT) in spontaneous ssion of 252Cf, and the design and development of two
time-of-
ight spectrometers aimed at identifying all collinear multi-body decay partners
directly. Prior to this study the only technique that was used at identifying decay partners
in CCT was the \missing mass" approach. In this approach only two partners are identi ed
directly with the third partner being identi ed by subtracting the two observed partners
from the initial mass of the nucleus.
The experimental results from the two spectrometer setups showed that it was possible
to identify all three partners of the CCT channel. The results also con rmed the existence
of the so called \Sn lost" CCT mode which was already observed in earlier experiments. / National Research Foundation (NRF) / Joint Institute of Nuclear Science (JINR) / Financial support from Dr D V Kamanim / Dept of Science and Technology (DST)
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Mögliche Korrelation zwischen dem Stadium der altersabhängigen Makuladegeneration und der zentralen HornhautdickeKoch, Christian 28 July 2016 (has links) (PDF)
Deutschsprachige Zusammenfassung
Dissertation zur Erlangung des akademischen Grades Dr. med.
Titel: Mögliche Korrelation zwischen dem Stadium der altersabhängigen Makuladegeneration und der zentralen Hornhautdicke
eingereicht von: Christian Koch
angefertigt an der: Klinik und Poliklinik für Augenheilkunde
Universität Leipzig
betreut von: Professor Dr. med. Peter Wiedemann
Klinik und Poliklinik für Augenheilkunde
Universität Leipzig
Monat und Jahr: Juni 2015
Annahme: Es soll ein statistischer Zusammenhang zwischen der zentralen Hornhautdicke in der Pupillenmitte mit dem nicht exsudativen frühen Stadium der AMD, dem exsudativen späten Stadium der AMD und einer Kontrollgruppe überprüft werden.
Methodik: Die erste Studiengruppe stellten 48 Augen von 48 Patienten mit einer Form der frühen AMD dar (Durchschnittsalter 75,4 Jahre, 70,8% der Probanden waren Frauen). Die zweite Studiengruppe bildeten 49 Augen von 49 Patienten mit einer Form der späten AMD (Durchschnittsalter 79,8 Jahre, 59,2% der Probanden waren Frauen). Als Kontrollgruppe wurden 49 Augen von 49 Individuen ohne retinale oder korneale Erkrankungen genutzt (Durchschnittsalter 68,9 Jahre, 59,2% der Probanden waren Frauen). Die Vermessung der Hornhautdicke in Pupillenmitte im Sinne der Hornhautmittendicke erfolgte als Pachymetrie mit der Oculus Pentacam.
Ergebnisse: Die durchschnittliche zentrale Hornhautdicke betrug bei der Kontrollgruppe 552,76 μm (SD 36,27 μm), bei der nicht exsudativen Gruppe 552,19 μm (SD 31,27 μm) und bei der exsudativen Gruppe 553,73 μm (SD 33,11 μm). Die Extrempunkte der Kontrollgruppe lagen bei 483 und 640 μm, der Gruppe der nicht exsudativen AMD bei 480 und 617 μm und Minimum und Maximum der exsudativen Gruppe bei 473 und 617 μm. Es gab keine statistisch signifikanten Unterschiede im arithmetischen Mittel der zentralen Hornhautdicke in Pupillenmitte bei der Studiengruppe mit früher AMD im Vergleich mit der Studiengruppe mit später AMD und jeweils im Vergleich zur Kontrollgruppe (P > 0,05).
Schlussfolgerung: Die Messwerte der zentralen Hornhautdicke bei Patienten mit früher AMD, später AMD und Kontrollindividuen unterscheiden sich nicht. Die Erhebung der Hornhautmittendicke bietet somit keine Screeningmöglichkeit zur Erkennung einer AMD. / English Abstract
Central corneal thickness in patients with AMD
Koch, C.; Jochmann, C.; Wiedemann, P.
University of Leipzig, Department of Ophthalmology and Eye Hospital, Leipzig, Germany
Purpose: To evaluate central corneal thickness in patients with AMD in the early and late phase and a control group.
Method: The first study group was made up of 48 eyes of 48 patients with early AMD (mean age 75.4 years, 70.8 % women), the second study group was made up of 49 eyes of 49 patients with late AMD (mean age 79.8 years, 59.2 % women). 49 eyes of 49 individuals without any retinal or corneal damage (mean age 68.9 years, 59.2 % women) were used as control group. The central corneal thickness was measured with the Oculus Pentacam pachymetry.
Results: The mean central corneal thickness in early non-exudative AMD group was found to be 552.19 μm (SD 31.27 μm), while the mean central corneal thickness in the late exudative AMD group was measured as 553.73 μm (SD 33.11 μm). The control group had a mean central corneal thickness of 552.76 μm (SD 36.27 μm). There were no statistically significant differences in the mean central corneal thickness in the early non-exudative AMD group in comparison with the late exudative AMD group and each of them compared to the control group (P > 0,05).
Conclusion: The central corneal thickness measurements do not differ in patients with early non-exudative AMD, late exudative AMD and control subjects.
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Estudo da transformação durante o resfriamento continuo e da microestrutura do aço microligado X80 utilizado na construção de tubos para transporte de gás natural e petróleo. / Study of the transformation during the continuous cooling and the microstructure of microalloyed steel X80 used in the building of pipelines for gas and oil transport.Gonzalez Ramírez, Mario Fernando 16 June 2008 (has links)
O crescente consumo de energia produzida a partir do petróleo e do gás natural conduz a melhoria das propriedades mecânicas dos aços microligados empregados na construção dos oleodutos e gasodutos para incrementar o transporte dos recursos a menores custos e elevar a confiabilidade. O aumento do controle das diferentes fases, agregados eutetóides, microconstituintes e precipitados neste tipo de aço, garante a melhoria na resistência mecânica, tenacidade e soldabilidade. Dentro deste contexto foi realizado um trabalho de caracterização microestrutural do aço um microligado para tubos API 5L X80 em amostras de aço como recebido e em diferentes condições de resfriamento. Para o estudo da cinética das transformações de fase, o aço microligado foi submetido a ensaios de dilatometria onde foram identificadas as temperaturas e tempos de início e fim de transformação de fases, para varias velocidades de resfriamento. A partir das diferentes temperaturas e tempos obtidos, em função das taxas de resfriamento, foi possível extrair a curva de Transformação por Resfriamento Continuo (TRC). Os dados da curva TRC foram comparados com as microestruturas de cada corpo de prova por meio de microscopia óptica (MO), microscopia eletrônica de varredura (MEV), microscopia eletrônica de varredura com Field Emission Gun (FEG) e microdureza, caracterizando a evolução morfológica da matriz ferrítica, agregados eutetóides e microconstituinte austenita/martensita (MA). Para a caracterização microestrutural das amostras também foram utilizadas técnicas de análise microestrutural como, nanodureza, análise por difração de raios X em amostras obtidas por extração de precipitados, saturação magnética e microscopia de força atômica (AFM). A técnica de saturação magnética foi desenvolvida por médio de curvas de histerese medidas em um histeresígrafo com peças polares e anel de Rowland para diversas amplitudes de intensidade de campo magnético. Esta técnica permitiu a detecção da saturação magnética do aço sem tratamento térmico e a saturação máxima nos aços com tratamento térmico, o que indicou a total transformação da austenita retida. A relação das duas saturações permitiu determinar a fração de austenita retida no MA. Para as medidas de nanodureza foi utilizado um nanodurômetro acoplado ao microscópio de força atômica (AFM). As nanodurezas obtidas em diferentes grãos foram comparadas com os valores constantes na literatura para identificar as fases, agregados eutetóides e possíveis precipitados da microestrutura. / The continuous increase of energy generated from petroleum and natural gas created the need to improve the mechanical properties of microalloyed steels used in gas and oil pipelines, in order to increase their flow with smaller costs and higher reliability. The control of the different phases, morphology of microconstituents like ferrite plus carbide aggregates and precipitates in this kind of steels is essential to the improvement of mechanical strength, toughness and weldability. In this context, a work of microestrutural characterization of a microalloyed steel for API X80 pipelines was carried out both on an as-received steel sample as in samples submitted to different cooling conditions. The kinetics of austenite transformations was investigated using dilatometric experiments, identifying start and end of the phase transformations as well as the time spent temperatures for the phase transformations at each cooling rate. The temperature and time curves obtained as a function of the cooling rates allowed the determination of a Continuous Cooling Transformation curve (CCT). The data from the CCT curve was compared with the microstructures of each sample through optical microscopy (OM), scanning electron microscopy (SEM), scanning electron microscopy with Field Emission Gun (FEG) and microhardness, characterizing the morphologic evolution of the ferritic matrix, ferrite plus carbide eutectoid aggregates (perlite and bainite) and the microconstituent martensite/austenite (MA). The microestrutural characterization of the samples was performed also using different techniques of microestrutural analysis: precipitate extraction followed by Xrays diffraction analysis, magnetic saturation and atomic force microscopy (AFM) measurements. The magnetic saturation technique was developed through hysteresis curves measured with a hysteresigraph with polar pieces and Rowland ring for several ranges of magnetic field intensity. This technique allowed to detect the magnetic saturation of the steel without thermal treatment and the maximum saturation in the heat treated steels were the retained austenite has transformed. The relationship between those saturations curves allowed a determination of the retained austenite fraction in the MA microconstituent. The nanohardness was measured using a specific device coupled to a atomic force microscope (AFM). The nanohardness of different grains were compared with the hardness values from the literature in order to help identify phases and microconstituents, as well as possible precipitates.
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Application of Computational Thermodynamic and Solidification Kinetics to Cold Sprayable Powder Alloy DesignBelsito, Danielle L 14 January 2014 (has links)
Military aircraft that require high maneuverability, durability, ballistic protection, reparability, and energy efficiency require structural alloys with low density, high toughness, and high strength. Also, repairs to these aircraft demand a production process that has the flexibility to be relatively in-situ with the same high-performance output. Materials produced by the cold spray process, a thermo-mechanical powder consolidation technique, meet many of the requirements. In accordance with President Obama’s 2011 Materials Genome Initiative, the focus of this effort is to design customized aluminum alloy powders which exploit the unique behavior and properties of the materials created by the cold spray process. Analytical and computational models are used to customize microchemistry, thermal conditioning, and solidification behavior of the powders by predicting equilibrium and non-equilibrium microstructure and resulting materials properties and performance. Thermodynamic, kinetic, and solidification models are used, including commercial software packages Thermo-Calc, Pandat™, and JMatPro®, and TC-PRISMA. Predicted powder properties can be used as input into a cold spray process impact model to determine the consolidated materials’ properties. Mechanical properties of powder particles are predicted as a function of powder particle diameter and are compared to experimental results.
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