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1
Valentini, Stefano. « Transport properties in multi-terminal topological superconductors ». Doctoral thesis, Scuola Normale Superiore, 2017. http://hdl.handle.net/11384/85902.
Texte intégralRésumé :
[excerpt from the introduction:] This PhD thesis project is set in the broad area of mesoscopic physics, which deals with
systems with size of few nanometers up to some micrometers. In particular, we focus on hybrid structures composed of superconductors and normal metals or semiconductors.
2
Sumner, Evan T. « Characterizing the Oncogenic Properties of C-terminal Binding Protein ». VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4153.
Texte intégralRésumé :
The paralogous C-terminal binding proteins (CtBP) 1 and 2 are evolutionarily conserved transcriptional coregulators that target and disrupt the expression of several genes essential for multiple cellular processes critical to regulating tumor formation. CtBP’s ability to govern the transcription of genes necessary for apoptosis, tumor suppression, invasion/migration and EMT gives rise to its oncogenic activities. Both isoforms of CtBP are found to be overexpressed in cancers including colorectal, pancreatic, ovarian, and breast, with higher levels correlating to lower overall median survival. Although multiple lines of evidence suggest CtBP plays a role in tumorigenesis, it has never been formally characterized as an oncogene. For this reason, the goal of this dissertation was to design a set of experiments to determine the transforming ability of CtBP2 in vitro using both murine and human fibroblast and in vivo using the Apcmin/+ mouse model of cancer. Specifically, we demonstrate that overexpression of CtBP2 alone can drive transformation of NIH3T3 cells leading to loss of contact inhibition, increased x invasion/migration, and anchorage independent growth. In addition, CtBP2 was found to cooperate with the large T-antigen (LT) component of the simian virus 40 (SV40) to lead to transformation of murine embryonic fibroblasts (MEFs) and with both LT and small T-antigen (ST) to induce migration/invasion and anchorage-independent growth in BJ human foreskin fibroblasts. To confirm the role of Ctbp2 in a mouse tumor model with Ctbp overexpression, we bred Apcmin/+ mice to Ctbp2 heterozygous (Ctbp2+/-) mice, which otherwise live normal lifespans. CtBP is a known target of the APC tumor suppressor and is thus stabilized in APC mutated human colon cancers and is found in high levels in Apcmin/+ polyps. Remarkably, removing an allele of Ctbp2 doubled the median survival of Apcmin/+ mice (P <0.001) and reduced polyp formation to near undetectable levels. These data suggest the importance of CtBP2 in driving cellular transformation and identify it as a potential target for prevention or therapy in APC mutant backgrounds.
3
Hollier, Mark John. « Properties of the C-terminal tail of HIV-1 gp41 ». Thesis, University of Warwick, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408463.
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4
Heffron, Kerensa. « Studies of the redox and catalytic properties of the anaerobic respiratory enzymes of Escherichia coli ». Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365375.
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5
Spilla, Samuele Verfasser], Janine [Akademischer Betreuer] Splettstößer, Barbara [Akademischer Betreuer] [Terhal et A. [Akademischer Betreuer] Napoli. « Coherence properties of superconducting flux qubits / Samuele Spilla ; Janine Splettstößer, Barbara Terhal, A. Napoli ». Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1127232096/34.
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Spilla, Samuele [Verfasser], Janine [Akademischer Betreuer] Splettstößer, Barbara [Akademischer Betreuer] Terhal et Anna [Akademischer Betreuer] Napoli. « Coherence properties of superconducting flux qubits / Samuele Spilla ; Janine Splettstößer, Barbara Terhal, A. Napoli ». Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://nbn-resolving.de/urn:nbn:de:hbz:82-rwth-2015-065886.
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7
Spilla, Samuele [Verfasser], Janine Akademischer Betreuer] Splettstößer, Barbara [Akademischer Betreuer] [Terhal et Anna [Akademischer Betreuer] Napoli. « Coherence properties of superconducting flux qubits / Samuele Spilla ; Janine Splettstößer, Barbara Terhal, A. Napoli ». Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1127232096/34.
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8
Nash, David Allan. « NPSNET : modeling the in-flight and terminal properties of ballistic munitions ». Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/38574.
Texte intégralRésumé :
Approved for public release; distribution unlimited.Graphical computer simulations provide a means through which weapon prototyping and tactical evaluations can be conducted at low cost, without the risks associated with the movement of equipment and firing of weapons. Because of the widespread use of ballistic munitions in the armed forces, a fundamental aspect of the implementation of such military simulations is a physical model that governs ballistic behavior. The modified point-mass trajectory model is used to implement ballistic trajectories within NPSNET, a real-time, graphical, three-dimensional simulation. A parallel algorithm is used to simulate the visual characteristics of shrapnel-producing explosions. A special case of ballistic trajectories involves the application of indirect fires. When a projectile travels along a curved path to the target area, rather than being propelled directly along the line of sight, much greater ranges can be achieved. This makes it possible to fire upon an enemy without directly exposing the firing elements to harm. As a result of these increased ranges, it is generally not possible for the firing element to acquire its own targets. Thus, an additional player is required to represent this tactic in a virtual world: the forward observer. An expert system is presented that mimics the cognitive contributions of a human forward observer.
9
Pfeffer, Andreas Helmut. « Electronic properties of diffusive three-terminal Josephson junctions : a search for non-local quartets ». Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY068.
Texte intégralRésumé :
Pendant ce travail de thèse, j'ai tout d'abord finalisé le développement d'un système expérimental unique dédié aux études de transport électronique de nanostructures multi-terminaux de faible impédance. Ce dispositif permet des mesures de conductance et de bruit à très basse température (30 mK), avec une résolution du pico-ampère en utilisant des SQUIDs comme amplificateurs de courant. Dans le chapitre 5, je fournis une description du fonctionnement de la mesure. De plus, je décris la calibration du dispositif et la manière de déduire des quantités physiques à partir des mesures.Au Chapitre 6, je décris des mesures de transport avec des jonctions diffusives à trois terminaux (trijonctions). Dans une géométrie, que l'on appelle T-shape, des électrodes supraconductrices d'Aluminium sont connectées entre-elles par une partie centrale métallique non-supraconductrice de Cuivre. Pour ces nanostructures, on observe des anomalies de conductance à basse tension qui n'ont jamais été observées expérimentalement. Ces anomalies de résistance/conductance ressemblant fortement à l'effet Josephson apparaissant lorsque deux des potentiels appliqués à la trijonction ont une somme nulle. Les anomalies sont présentes sur une large échelle de tension sans perte d'amplitude. De-même, elles montrent une grande robustesse en température. Des expériences sous champ magnétique appliqué montrent une forte suppression des anomalies pour un champ magnétique correspondant à flux magnétique dans la partie normale de l'ordre d'un quantum de flux. Ceci indique qu'un mécanisme cohérent de phase doit être à l'origine des anomalies. Dans la littérature, deux mécanismes sont proposés pour expliquer ces effets.Le premier, nommé "mode-locking", est un accrochage dynamique des courants Josephson ac, qui est induit par l'environnement expérimental (circuit). Cette situation a été étudiée dans les années soixante sur des microstructures Josephson couplées à base de liens faibles. Pour tester cette explication, nous avons mesuré un échantillon composé de deux jonctions Josephson spatialement séparées. Les anomalies n'apparaissent pas dans une telle géométrie, pas même avec une amplitude réduite. Ceci indique qu'une synchronisation par l'environnement expérimental ne peut pas être à l'origine des anomalies observées. Le deuxième mécanisme théorique évoqué est nommé "mode de quartet" et a été proposé récemment par Freyn et collaborateurs. L'une des électrodes supraconductrices distribue alors des doublets de paires de Cooper. Chacune de ces deux paires se scindent alors en deux quasiparticles se propageant chacune vers deux contacts supraconducteurs différents. Dans un tel mécanisme deux quasiparticules, issues de deux paires de Cooper différentes, arrivent sur chacun des deux contacts supraconducteurs. Lorsque les tensions appliquées entre le contact supraconducteurs émetteur et les deux autres contacts sont exactement opposés, les phases des fonctions d'ondes électroniques des quasiparticules arrivant sur un même contact supraconducteur sont telles que ces deux quasiparticules peuvent se recombiner pour former une paire de Cooper. Par ce mécanisme le doublet de paires de Copper émis se distribue de manière cohérente en deux paires de Cooper chacune dans un contact supraconducteur différent.Ce mécanisme est favorable, car il est robuste envers le désordre et peut ainsi exister sur une large échelle de tensions.Au cours de cette thèse, j'ai montré que ces anomalies sont effectivement présentes pour des tensions appliquées correspondant à des énergies bien supérieures à l'énergie de Thouless. A contrario, les effets cohérents responsables de l'effet Josephson ac doivent être fortement atténués sur cette même échelle d'énergie, ce qui rend peu probable le mécanisme de mode-lockingDuring this PhD, I have first finished the development of a unique experimental set-up, dedicated for studies of electronic transport of low impedance multi-terminal nanostructures. This set-up allows conductance and noise measurements at very low temperature (30 mK), with a resolution of a few pico-ampere by using SQUIDs as current amplifiers. In chapter 5, I give some explanation of the measurement working principle. Furthermore, I explain the calibration of the experimental set-up as well as how to extract physical quantities from the measurements.In chapter6, I explain transport measurements on diffusive tri-terminal junctions (tri-junction). In a T-shape called geometry, the superconducting Al-electrodes are connected via a common metallic, non-superconducting part of Copper. For these nanostructures, we observe features in the conductance at low voltage, which have been never observed yet experimentally. These features in conductance/resistance have a striking resemblance with a dc-Josephson effect, appearing when two applied potentials on the tri-junction compensate exactly each other.In literature, two mechanisms are proposed to explain this effect.The first mechanism, called "mode-locking", corresponds to a dynamic locking of ac-Josephson currents, which is induced by the experimental environment (circuit). This situation has been extensively studied in the 60's on coupled microstructures, based on weak links. In order to test this explanation, we have measured a junction, which is composed of two spatially separated Josephson junctions. The anomalies does not show up in such a geometry, even not with strongly reduced amplitude. This indicates, that synchronization via the experimental environment can't be the origin of the observed features. The second theoretical mechanism is named "quartet-mode" and has been recently proposed by Freyn and Co-workers. In this process, one superconducting electrode emits doublets of Cooper-pairs. Each of the two pairs splits into two quasi particles propagating toward different superconducting contacts. In such a mechanism, two quasi-particles originating of two different Cooper-pairs, arrive each in the two superconducting contacts. If the applied voltage between the emitting superconducting contact and the two other contacts is exactly opposite, the phase of the electronic wave functions of the arriving quasi-particles on the same superconducting contact are such, that these two quasi-particles can recombine by forming a Cooper-pair. Due to this mechanism, the emitted doublet of Cooper-pairs is coherently distributed as two Cooper-pairs, each of them in a different superconducting contact. This mechanism is favored, since it is robust with respect to disorder and can hence also exist over a large range of voltage. During this PhD, I have shown that these anomalies are indeed present for applied voltage corresponding to energies well above the Thouless energy. Argumentum a contrario, the coherent effects responsible for the ac Josephson-effect have to be strongly attenuated over the same range of energy, which makes low probable the effect of mode-locking
10
Mills, Jamie E. « Structural investigation and allosteric properties of a unique disulfide bond in C-terminal Src kinase ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3320620.
Texte intégralRésumé :
Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed September 24, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 110-118).
11
Radini, Ibrahim Ali M. « The synthesis and properties of liquid crystals with bulky terminal groups for bookshelf geometry ferroelectric mixtures ». Thesis, University of Hull, 2010. http://hydra.hull.ac.uk/resources/hull:4924.
Texte intégralRésumé :
The area of liquid crystals has received a substantial research effort over the last century, particularly when the beneficial applications such as Liquid Crystal Displays (LCDs) were realised and developed. The changes to the molecular structure of liquid crystals can have a significant effect upon their mesomorphism and ferroelectric properties. Most of the research in liquid crystal for display applications concentrates on the design and synthesis of novel mesogenic cores to which straight terminal alkyl or alkoxy chains are attached. However, little is known about the effects upon the mesomorphism and ferroelectric properties of varying the terminal chains. The synthesis and mesomorphic properties of a systematic range of ortho difluoroterphenyls with a bulky terminal chain are detailed. The bulky terminal chain consists of either a tertiarybutyl group or a trimethylsilyl unit, each separated from the core by a short (dimethylene) chain, with the other terminal chain being either octyloxy or heptyl. Unusually for liquid crystals with bulky terminal chains, the smectic phase stability (particularly smectic C) is upheld by more than the nematic phase stability, and in most cases the smectic C phase stability is actually higher than comparable analogues with conventional unbranched terminal chains. It is postulated that the surprisingly high smectic C phase stability results from a phase separation effect due to the incompatibility of the spherical bulky group and the conventional unbranched terminal chain, hence implying that the smectic 'layers' are well defined, and such definition of the layers bodes well for bookshelf geometry in ferroelectric mixtures. Two mono- and four trifluoroterphenyls with a bulky terminal chain were prepared in this work to study the effect on the mesomorphic behaviour of varying the degree of fluoro substituents upon the multi-ring system. Two chiral ortho difluoro-substituted terphenyl compounds were prepared also in this work for future ferroelectric mixtures.
12
Learmont, Jessica. « Prion-like properties of the N-terminal domains of the rat and human FoxG1 transcription factors ». Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/4285.
Texte intégralRésumé :
Word processed copy.Includes bibliographical references (leaves 82-90).
The purpose of this study was to investigate the possible prion-like properties of the N-terminal domains of the winged-helix transcription factor FoxG1.
13
Biswas, Soma. « EFFECT OF LINKER CHEMISTRY AND TERMINAL SUBSTITUENTS ON THE LIQUID CRYSTALLINE PROPERTIES OF BIS(AZOBENZENE) MESOGENS ». Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193436.
Texte intégralRésumé :
Azobenzene upon photochemical E/Z isomerization changes both its shape and size. The E-azobenzene moiety falls in the class of calamitic liquid crystalline mesogens, producing a wide variety of mesophases. Two series of linear bis(azobenzene) compounds, one with phenyl benzoate linkage and the other with benzyl benzoate linkage were synthesized. The termini of these molecules ranged from a dodecyloxy chain to hydrophobic amphiphilic dendrons up to first generation. We determined the effects of both the linkages and generation number on the mesogenic properties of these compounds. Our results show that the mesogenic behavior of these bis(azobenzene) compounds are highly dependent on the linkages between individual azobenzenes and that for the bis(azobenzene) compounds of the phenyl benzoate series, generation number had an effect on the liquid crystalline mesophase of the compounds
14
Sgura, Ricardo. « Tratamento de superfície de porcelanas dentárias pela irradiação com laser de CO2 ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-10092013-201616/.
Texte intégralRésumé :
Este estudo teve como objetivo testar o laser de CO2 como um agente de tratamento de superfície de porcelanas dentárias. Material e Métodos: O estudo foi dividido em duas etapas: na primeira etapa, discos de porcelana (3,5 mm diam. x 2,0 mm espess.) das marcas VM7, VM9 e VM13 (VITA) foram sinterizados e tiveram uma de suas faces asperizadas por uma ponta diamantada 2134F para acabamento. Os espécimes foram então divididos em grupos de acordo com os seguintes tratamentos: nenhum (C), auto-glaze em forno (G) e irradiação com laser (L) de CO2 (Coherent, = 10,6 m, 35 W) de forma contínua com 40, 45 ou 50 W/cm2 nos tempos de 3, 4 ou 5 minutos (n=7). Nesta primeira etapa, as caracterizações das amostras constaram de: difratometria por raios-X, diferença de cor (Easyshade VITA), rugosidade superficial (Surftest 301, Mitutoyo) e análise visual por meio de esteromicroscopia e MEV. Um espécime de VM9 de cada grupo foi polido e levado a um exame por microscopia de força atômica (MFA). A segunda etapa consistiu na sinterização de discos das três porcelanas nas mesmas dimensões da etapa anterior, porém submetidos a um polimento de uma das superfícies com soluções diamantadas de granulação decrescente até 1 m. Os grupos testados foram os mesmos da primeira etapa, com exceção dos grupos irradiados com 40W/cm2. As caracterizações que se seguiram foram (n=10): microdureza Vickers, tenacidade à fratura, porosidade superficial, razão de contraste (RC) e capacidade de mascaramento (CM). Resultados: A rugosidade de espécimes asperizados foi diminuída pela aplicação do laser nas irradiâncias de 45 e 50 W/cm2, similar ao auto-glaze em forno, sem alteração de cor perceptível para a quase totalidade dos grupos irradiados. Houve um aumento do conteúdo cristalino das porcelanas VM9 e VM13 após a irradiação com o laser. As micrografias (MEV) demonstraram padrão de superfície homogêneo para os espécimes dos grupos irradiados a 50 W/cm2 e G. Os resultados da segunda etapa apontaram para alterações na microdureza e tenacidade à fratura na dependência da marca comercial e das irradiâncias estudadas. Quanto à porosidade, as porcelanas VM7 e VM13 apresentaram um aumento na fração volumétrica de poros, enquanto a porcelana VM9 irradiada apresentou-se semelhante a G. As médias de RC e CM indicaram um aumento na opacidade das porcelanas VM7 e VM13 irradiadas com o laser. Conclusão: Em condições específicas, o laser de CO2 é capaz de produzir uma lisura de superfície semelhante ao auto-glaze, com pequenas alterações nos aspectos ópticos e mecânicos. As diferentes marcas comerciais de porcelana apresentaram comportamentos distintos em relação aos tratamentos aplicados.Glazing porcelain is an important procedure in dentistry that leads to surface smoothness, to less plaque accumulation and to brightness, especially after a chair side adjustment. Despite a good absorption of CO2 laser wavelength by dental porcelain it has not yet been tested as an alternative to oven glaze. Aim: This study tested CO2 laser as a heat source in surface treatment of dental porcelains. Material and Methods: This study was divided in two stages: at the first stage porcelain discs (VM7, VM9, VM13 VITA; 3.5 diam. x 2.0 mm thickness) were sintered, machined and had one of their sides grounded by a diamond bur (2134F KG Sorensen) simulating a chair side adjustment in clinical office. Specimens were then divided into groups according to treatment: no treatment (C); auto-glazed in conventional furnace (G) and submitted to CO2 continuous laser irradiation (Coherent, = 10.6 m; output power = 35 W, 0.5 cm laser beam) in 40, 45 or 50 W/cm2 for 3, 4 or 5 minutes (n=7). Specimens were supported by a ceramic refractory. At this first stage, the characterization consisted of X-ray diffraction (RU-200B, Rigaku), color difference (E) (Easyshade VITA), roughness (Surftest 301, Mitutoyo) and analysis of images achieved by stereomicroscopy (SZ61, Olympus) and SEM (Stereoscan 440, LEO). A VM9 specimen of each group had one of their side polished and was submitted to atomic force microscopy (AFM) Nanoscope IIIA (Veeco). In the second stage discs with the same dimension described above were sintered and polished with diamond solutions (Ecomet 3; 1 m). The same groups were tested except 40W/cm2 irradiance. Specimens were submitted to the following characterizations (n=10): Vickers microhardness test, fracture toughness by indentation fracture (HMV, Shimadzu), surface porosity (HMV, Image J software), contrast ratio (CR) and masking ability (MA) (CM-3770d, Konica Minolta). Results from both stages were submitted to one-way-ANOVA or Kruskall-Wallis test. A post-hoc Tukey test was applied when necessary ( = 0.05). Results: Ground specimens showed a reduction in roughness after laser irradiation (45 and 50 W/cm2), comparable to oven-glazed specimens with almost no color change. SEM images presented similarity between a irradiated group (50W/cm2) and G. AFM test revealed the formation of long rounded peaks and long valleys after laser exposition. Second stage results pointed to changes in microhardness and fracture toughness of irradiated specimens depending on the porcelain and irradiance tested. Regarding porosity, after laser exposition, porcelain VM7 and VM13 presented an increase in pores (area fraction) for the majority of groups while VM9 porcelain didnt show any increase in porosity after laser incidence. CR and MA means pointed to an increase in porcelain opacity to irradiated specimens of VM7 and VM13. Conclusion: Under specific conditions CO2 laser was able to produce a surface smoothness similar to auto-glaze, despite punctual changes in some optical and mechanical properties. The different brands presented distinct effects after laser heat treatment.
15
Matheus, Fernanda Aparecida. « Ciência, terra e poder : uso e apropriação territorial das terras públicas pelo capital no Sudoeste Paulista / ». Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153404.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O presente trabalho se propõe a debater a questão das terras públicas na região Sudoeste Paulista, compilar informações sobre localização, posse e uso das áreas existentes, promovendo uma análise crítica sobre a situação de uso destas na atualidade e as disputas e possibilidades de destiná-las para projetos de assentamentos de trabalhadores rurais sem terras, a partir da discussão sobre a questão agrária e o avanço do agronegócio, desenvolvimento e função socioambiental da propriedade pública. A área de abrangência deste estudo foi a região de Itapeva, delimitada a partir da definição de regiões administrativas do governo do estado de São Paulo. Nesse contexto e espaço geográfico, há um contraste e contradição entre um elevado grau de desenvolvimento do agronegócio, com extensas áreas cultivadas com soja e espécies madeiráveis destinadas à indústria de papel e celulose e uma intensa atividade mineradora; com uma população empobrecida que sobrevive e resiste em meio a esse processo de expansão, e que a cada dia se vê alijada das poucas possibilidades de trabalho temporário na agricultura, em uma região basicamente agrícola. Outra reflexão presente neste trabalho será sobre o papel da produção técnico-científica para a promoção de distintos projetos societários, representados pelo projeto do agronegócio orientado pela lógica de reprodução e acumulação de capital e da reforma agrária desde a lógica dos movimentos sociais de luta pela terra na atualidade, orientados pela lógica da reprodução da vida e respeito aos limites da natureza. As terras públicas existentes na região, de modo geral, estão sob domínio de instituições de ensino, pesquisa, extensão e fomento, portanto seu uso deve estar voltado essencialmente para a produção de ciência e tecnologia e cumprir função socioambiental, buscando garantir condições de vida digna e acesso a um ambiente saudável para o conjunto da sociedade, o que pressupõe a adoção por parte do aparato estatal de mecanismos de gestão e controle democráticos. Porém, estas áreas, na atualidade são foco de conflitos e disputas envolvendo latifúndio-agronegócio, Estado e trabalhadores rurais sem terras, a partir de projetos completamente antagônicos e não se observa a existência de mecanismos de controle social e territorial democrático da gestão e da decisão sobre o uso destas.
The present paper proposes to discuss the question of public rural properties in the Southwest of São Paulo region, to compile information about localization, ownership and utilization of the existing areas. Promoting a critical analysis about the status of use of these in the present and the disputes and possibilities of assigning them for projects of settlements of landless workers, from the discussion about agrarian question and the advance of agribusiness, development and socioenvironmental function of public property. The scope of this study is the region of Itapeva, delimited from the definition of administrative regions of the state government of São Paulo. In this context and geographic space, there is a contrast and contradiction between a high level of development of agribusiness, with extensive areas cultivated with soybeans and wood’s species for the cellulose and paper industry and an intense mining activity; with a poor population who survives and resists in the midst of this process of expansion, and who every day they feel expelled the few temporary labor opportunities in agriculture, in an agricultural region basically. Another reflection in this paper will be about the role of technical-scientific production for the promotion of different corporate projects, represented by the agribusiness project oriented by the logic of reproduction and capital accumulation and from the agrarian reform since the logic of the social movements of struggle for the land at present, guided by the logic of the reproduction of life and respect for the limits of nature. The public lands in the region, in general, are in control of institutions of education, research, extension and development, therefore its use must be directed essentially to the production of science and technology and fulfill your socioenvironmental function, seeking to ensure dignified living conditions and access to a healthy environment for society as a whole, what presupposes the adoption by the state apparatus of mechanisms of democratic management and control. But, these areas, in fact, they are the focus of conflicts and disputes involving the latifundio-agribusiness, State and landless workers, from completely antagonistic projects and the existence of mechanisms of democratic social and territorial control of the management and the decision on their use is not observed.
El presente trabajo se propone discutir la cuestión de las tierras públicas en la región Suroeste Paulista, compilar informaciones sobre localización, posesión y uso de las áreas existentes, promoviendo un análisis crítico sobre la situación de uso de éstas en la actualidad y las disputas y posibilidades de destinarlas para proyectos de asentamientos de trabajadores rurales sin tierra a partir de la discusión sobre la cuestión agraria y el avanzo del agronegocio, desarrollo y función socio-ambiental de la propiedad pública. El área que abarca este estudio fue la región de Itapeva, delimitada a partir de la definición de regiones administrativas del gobierno del estado de São Paulo. En este contexto y espacio geográfico, hay un contraste y contradicción entre un elevado grado de desarrollo del agronegocio, con extensas áreas cultivadas con soya y especies maderables destinadas a la industria de papel y celulosa y una intensa actividad minera; con una población empobrecida que sobrevive y resiste en medio de este proceso de expansión, y que a cada día se ve desechada de las pocas posibilidades de trabajo temporario en la agricultura, en una región básicamente agrícola. Otra reflexión presente en este trabajo será sobre el papel de la producción técnico-científica para la promoción de distintos proyectos corporativos, representados por el proyecto del agronegocio orientado por la lógica de reproducción y acumulación de capital y de la reforma agraria desde la lógica de los movimientos sociales de lucha por la tierra en la actualidad, orientados por la lógica de la reproducción de la vida y respeto a los límites de la naturaleza. Las tierras públicas existentes en la región, de modo general, están bajo el dominio de instituciones de enseñanza, investigación, extensión y fomento, por lo tanto su uso debe estar direccionado esencialmente para la producción de ciencia y tecnología y cumplir función social y ambiental, buscando garantizar condiciones de vida digna y acceso a un ambiente saludable para el conjunto de la sociedad, lo que presupone la adopción por parte del aparato estatal de mecanismos de gestión y control democráticos. Pero estas áreas, en la actualidad son foco de conflictos y disputas involucrando latifundio-agronegocio, Estado y trabajadores rurales sin tierra, a partir de proyectos completamente antagónicos y no se observa la existencia de mecanismos de control social y territorial democrático de la gestión y de la decisión sobre el uso de éstas.
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Schröder, Oliver. « Studies on molecular properties and functional regulation of terminal leukotriene C₄ synthases and cysteinyl-leukotriene receptor signalling in human endothelium / ». Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-146-3/.
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Mitsche, Matthew Alvin. « Interfacial properties of the n-terminal lipid-binding domains of apolipoprotein B and their role in triacylglyceride-rich lipoprotein assembly ». Thesis, Boston University, 2012. https://hdl.handle.net/2144/12527.
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Thesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.ApolipoproteinB (ApoB) is the principal protein component of triacylglyceride (TAG)-rich lipoproteins that are responsible for distribution of hydrophobic lipids to peripheral tissues and are the precursors to low density lipoprotein (LDL). TAG-rich lipoprotein assembly is initiated by the N-terminus of ApoB co-translationally binding and remodeling the luminal leaflet of the rough-ER. In this thesis, the adsorption and interfacial remodeling of the two N-terminal lipid-binding domains of ApoB (ApoB6-13 and 813-17) were characterized at a triolein/water (TO/W) and TO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/W interface using drop tensiometry. A method was developed to form a monolayer of POPC at a TO/W interface and protocols were developed to characterize the exchangeability, surface pressure (Π)-area isotherm, and exclusion Π (ΠEX) at a TO/W or TO/POPC/W interface. A model for the behavior of amphipathic α-helices at a lipid/water interface was investigated by comparing the N- and C- termini of ApoA-1 ([1-44]ApoA-1 (N44) and [198-243]ApoA-I (C46)) using these protocols. Both helical peptides had a Π dependent surface conformation and had a higher affinity for a TO/POPC/W interface than a TO/W interface. The N-terminal lipid-binding domain of ApoB (ApoB6-13), the α-helical domain (aHD), has 17 α-helices with a heterogeneous amphipathic cross-section. The second lipid-binding domain, the C-Sheet (ApoB13-17), is 6 amphipathic β-strands. The adsorption, stress response, and viscoelasticity of the αHD and C-Sheet domains were generally consistent with the behavior of model amphipathic α-helices and β-strands, respectively. The αHD domain had a higher affinity for a TO/POPC/W interface than a TOIW interface, while the C-Sheet had a higher affinity for a TO/W interface. POPC shielded the C-Sheet from binding TO. The αHD adsorbed to a TO/W interface in a compact conformation where only the N-terminal eight helices interacted with the surface. When the protein monolayer was decompressed, the C-terminal helices bound the lipid. When adsorbed ApoB6-13 was compressed, theN-terminal four helices were progressively expelled from the surface. The remodeling occurred at five distinct transition points where the helices rearranged. There was no evidence of major remodeling of the C-Sheet during expansion and compression. This evidence was used to develop a more detailed model for the initiation of TAG-rich lipoprotein assembly.
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Alberti, Michele. « On operational properties of quantitative extensions of lambda-calculus ». Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4076/document.
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Cette thèse porte sur les propriétés opérationnelles de deux extensions quantitatives du λ-calcul pur : le λ-calcul algébrique et le λ-calcul probabiliste.Dans la première partie, nous étudions la théorie de la β-réduction dans le λ-calcul algébrique. Ce calcul permet la formation de combinaisons linéaires finies de λ-termes. Bien que le système obtenu jouisse de la propriété de Church-Rosser, la relation de réduction devient triviale en présence de coefficients négatifs, ce qui la rend impropre à définir une notion de forme normale. Nous proposons une solution qui permet la définition d'une relation d'équivalence sur les termes, partielle mais cohérente. Nous introduisons une variante de la β-réduction, restreinte aux termes canoniques, dont nous montrons qu'elle caractérise en partie la notion de forme normale précédemment établie, démontrant au passage un théorème de factorisation.Dans la seconde partie, nous étudions la bisimulation et l'équivalence contextuelle dans un λ-calcul muni d'un choix probabliste. Nous donnons une technique pour établir que la bisimilarité applicative probabiliste est une congruence. Bien que notre méthode soit adaptée de celle de Howe, certains points techniques sont assez différents, et s'appuient sur des propriétés non triviales de « désintrication » sur les ensembles de nombres réels. Nous démontrons finalement que, bien que la bisimilarité soit en général strictement plus fine que l'équivalence contextuelle, elles coïncident sur les λ-termes purs. L'égalité correspondante est celle induite par les arbres de Lévy-Longo, généralement considérés comme l'équivalence extensionnelle la plus fine pour les λ-termes en évaluation paresseuseIn this thesis we deal with the operational behaviours of two quantitative extensions of pure λ-calculus, namely the algebraic λ-calculus and the probabilistic λ-calculus.In the first part, we study the β-reduction theory of the algebraic λ-calculus, a calculus allowing formal finite linear combinations of λ-terms to be expressed. Although the system enjoys the Church-Rosser property, reduction collapses in presence of negative coefficients. We exhibit a solution to the consequent loss of the notion of (unique) normal form, allowing the definition of a partial, but consistent, term equivalence. We then introduce a variant of β-reduction defined on canonical terms only, which we show partially characterises the previously established notion of normal form. In the process, we prove a factorisation theorem.In the second part, we study bisimulation and context equivalence in a λ-calculus endowed with a probabilistic choice. We show a technique for proving congruence of probabilistic applicative bisimilarity. While the technique follows Howe's method, some of the technicalities are quite different, relying on non-trivial "disentangling" properties for sets of real numbers. Finally we show that, while bisimilarity is in general strictly finer than context equivalence, coincidence between the two relations is achieved on pure λ-terms. The resulting equality is that induced by Lévy-Longo trees, generally accepted as the finest extensional equivalence on pure λ-terms under a lazy regime
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Rahn, Marco Aur?lio dos Santos. « Estudo das propriedades termof?sicas com varia??o da expansibilidade de comp?sito desenvolvido com matriz PUR-NOP e carga funcional de argilomineral ». Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15575.
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Previous issue date: 2011-07-11Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
In this study were conducted experimental procedures for determination of variation of the expandability of rigid polyurethane foam (PUR) from a natural oil polyol (NOP), specifically the Castor oil plant, Ricinus communis, pure and additions of the vermiculite in phase dispersed in different percentage within a range from 0% to 20%, mass replacement. From the information acquired, were defined the parameters for production of bodies of test, plates obtained through controlled expansion, with the final volume fixed. Initially, the plates were subjected to thermal performance tests and evaluated the temperature profiles, to later be extracted samples duly prepared in accordance with the conditions required for each test. Was proceeded then the measurement of the coefficient of thermal conductivity, volumetric capacity heat and thermal diffusivity. The findings values were compared with the results obtained in the tests of thermal performance, contributing to validation of the same. Ultimately, it was investigated the influence that changes in physical-chemical structure of the material had exerted on the variation of thermophysical quantities through gas pycnometry, scanning electron microscopy (SEM) combined with energy dispersive X-ray fluorescence spectroscopy (EDXRF), infrared spectroscopy using Fourier transform (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Based on the results obtained was possible to demonstrate that all load percentage analyzed promoted an increase in the potential expansion (PE) of the resin. In production of the plates, the composites with density near at the free expansion presented high contraction during the cure, being the of higher density adopted as definitive standard. In the thermal performance tests, the heating and cooling curves of the different composites had presented symmetry and values very close for lines of the temperature. The results obtained for the thermophysical properties of composites, showed little difference in respect of pure foam. The percentage of open pores and irregularities in the morphology of the composites were proportionate to the increment of vermiculite. In the interaction between the matrix and dispersed phase, there were no chemical transformations in the region of interface and new compounds were not generated. The composites of PUR-NOP and vermiculite presented thermal insulating properties near the foam pure and percentage significantly less plastic in its composition, to the formulation with 10% of load
Neste estudo, foram realizados procedimentos experimentais para determina??o da varia??o da expansibilidade da espuma r?gida de poliuretano (PUR) de um poliol de ?leo natural (NOP), especificamente o de mamona, Ricinus communis, puro e acrescido de vermiculita na fase dispersa, em distintos percentuais, dentro de uma faixa de 0% a 20%, de substitui??o em massa. A partir das informa??es adquiridas, foram definidos os par?metros para produ??o dos corpos de prova, placas obtidas atrav?s de expans?o controlada, com volume final fixo. Inicialmente, as placas foram submetidas a testes de desempenho t?rmico, sendo avaliados os perfis de temperatura, para posteriormente serem extra?das amostras, devidamente preparadas conforme as condi??es exigidas para cada ensaio. Procedeu-se ent?o a medi??o do coeficiente de condutividade t?rmica, capacidade t?rmica volum?trica e difusividade t?rmica. Os valores encontrados foram comparados com os resultados obtidos nos testes de desempenho t?rmico, contribuindo para valida??o dos mesmos. Por fim, foi investigada a influ?ncia que as altera??es na estrutura f?sico-qu?mica do material, exerceram sobre a varia??o das grandezas termof?sicas, por meio de picnometria a g?s, microscopia eletr?nica de varredura (MEV) combinada com espectroscopia de fluoresc?ncia de raios-X por energia dispersiva (EDXRF), espectroscopia de infravermelho com transformada de Fourier (FTIR), an?lise termogravim?trica (TGA) e an?lise t?rmica diferencial (DTA). Com base nos resultados obtidos foi poss?vel demonstrar que todos os percentuais de carga analisados promoveram um aumento do potencial de expans?o (PE) da resina. Na produ??o das placas, os comp?sitos com densidade pr?xima ? expans?o livre apresentaram grande contra??o na cura, sendo adotados os de maior densidade como padr?o definitivo. Nos ensaios de desempenho t?rmico, as curvas de aquecimento e resfriamento dos diferentes comp?sitos apresentaram simetria e valores muito pr?ximos para as linhas de temperatura. Os resultados obtidos para as propriedades termof?sicas dos comp?sitos, demonstraram pouca diferen?a em rela??o aos da espuma pura. O percentual de poros abertos e irregularidades na morfologia dos comp?sitos foram proporcionais ao incremento da vermiculita. Na intera??o entre matriz e fase dispersa n?o ocorreram transforma??es qu?micas na regi?o de interface e n?o foram gerados novos compostos. Os comp?sitos de PUR-NOP e vermiculita apresentaram propriedades isolantes t?rmicas pr?ximas as da espuma pura e percentual significativamente menor de pl?stico em sua composi??o, para a formula??o com 10% de carga
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Debnath, Dibyendu. « SYNTHESIS AND VISCOELASTIC PROPERTIES OF GELS OBTAINED FROM LINEAR AND BRANCHED POLYMERS ». University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525400236218684.
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Oliveira, Marco Aurélio de [UNESP]. « Investigação das propriedades físicas do sistema titanato de bário modificado com íons doadores nos sítios A e/ou B ». Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152071.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O titanato de bário (BaTiO3, BT) é um material ferroelétrico com diversas aplicações, dentro do mercado de componentes eletrônicos, devido às excelentes propriedades físicas que manifesta, em relação a outros sistemas ferroelétricos, continuando a atrair durante várias décadas o interesse científico e comercial. Dentre o grande número de trabalhos sobre o sistema BT reportados na literatura muitos são associados à vasta gama de aplicações para a indústria eletro-eletrônica, dentre as quais se destacam o uso em dispositivos para capacitores, termistores, entre outros. A dopagem do BaTiO3 com íons doadores implica na mudança de algumas propriedades físicas, que conduzem a comportamentos anómalos em determinados parâmetros físicos, cuja natureza ainda não tem sido muito esclarecida, embora muitos trabalhos tenham se empenhado para tentar justificar tais efeitos. Neste contexto, neste trabalho, as propriedades físicas do sistema BaTiO3 serão investigadas considerando a adição de elementos doadores, nos sítios A e B da estrutura. Em particular, os íons de gadolínio (Gd3+) e nióbio (Nb5+) serão usados como modificadores da estrutura perovskita em substituição dos íons de bário (Ba2+) e titânio (Ti4+) nos sítios A e B, respectivamente, considerando as fórmulas químicas Ba1-xGdxTiO3 e BaTi1-x NbxO3 (sendo x = 0.001, 0.002, 0.003, 0.004 e 0.005). As propriedades estruturais e microestruturais foram investigadas à temperatura ambiente, enquanto as propriedades dielétricas e elétricas foram analisadas em uma ampla faixa de temperatura e frequência. Em particular, os efeitos condutivos proporcionados pela dopagem dos íons doadores em diferentes sítios cristalográficos, cujo estudo ainda não foi reportado na literatura, foram cuidadosamente investigados para melhor compreender os fatores que influenciam e determinam as propriedades semicondutoras de tais materiais, visando aprimorar no entendimento a nível microscópico e macroscópico dos fatores que influenciam e originam os mecanismos condutivos nestes materiais, fatores determinantes para uma posterior aplicação na indústria eletroeletrônica. Os materiais foram obtidos a partir do método de Pechini (ou Método dos Precursores Poliméricos), bem conhecido na literatura por ser um método muito eficiente, quando comparado com métodos convencionais para síntese de materiais policristalinos, pois apresenta inúmeras vantagens, tais como a síntese em baixas temperaturas, baixa contaminação, maior controle estequiométrico, alta homogeneização e possibilidade de obtenção de pós em escala nanométrica.
Barium titanate (BaTiO3, BT) is a ferroelectric material with several applications for the electronic components market, due to its excellent physical properties when compared to other ferroelectric systems. So that, BT continues up today attracting the scientific and commercial interest for several decades. Among the large number of papers on the BT system reported in the literature, many are associated with the wide range of applications in the electric and electronic industry, where the use in capacitors, thermistors and other devices stands out. By doping BaTiO3 with donor ions implies in the change of some physical properties leading to abnormal behaviors in certain physical parameters. The nature of these changes is not yet very clear, although many papers have been reported trying to justify such effects. In this context, this work aims the investigation of the physical properties of the BaTiO3 system, considering the addition of donor elements in the A- and B-sites of the structure. In particular, the gadolinium (Gd3+) and niobium (Nb5+) ions will be used as modifiers on the perovskite structure by substitution of barium (Ba+2) and titanium (Ti+4) ions in the A- and B-site, respectively, considering the Ba1-xGdxTiO3 and BaTi1-x NbxO3 ( where x = 0.001, 0.002, 0.003, 0.004 and 0.005). The structural and microstructural properties were investigated at room temperature, while the electrical and dielectric properties were analyzed in a wide range of temperature and frequency. Particularly, the conductive effects provided by the doping with donor ions in different crystallographic sites, whose study has not yet been reported in the literature, were carefully investigated to better understand the factors that influence and determine the semiconductor properties of such materials. The objective is to enhance the understanding of the factors that influence and originate the conductive mechanisms in these materials at the microscopic and macroscopic level, therefore determining factors for a subsequent application in the electronics industry. The materials were obtained from the Pechini method (known as the Polymeric Precursors Method). This method is well known in the literature because it is a very efficient method, when compared with conventional methods for synthesis of polycrystalline materials, because of the numerous advantages it presents, such as the synthesis at low temperatures, low contamination, greater stoichiometric control, high homogenization and possibility of obtaining nanoscale powders.
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Oliveira, Marco Aurélio de. « Investigação das propriedades físicas do sistema titanato de bário modificado com íons doadores nos sítios A e/ou B / ». Ilha Solteira, 2017. http://hdl.handle.net/11449/152071.
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Orientador: José de los Santos GuerraResumo: O titanato de bário (BaTiO3, BT) é um material ferroelétrico com diversas aplicações, dentro do mercado de componentes eletrônicos, devido às excelentes propriedades físicas que manifesta, em relação a outros sistemas ferroelétricos, continuando a atrair durante várias décadas o interesse científico e comercial. Dentre o grande número de trabalhos sobre o sistema BT reportados na literatura muitos são associados à vasta gama de aplicações para a indústria eletro-eletrônica, dentre as quais se destacam o uso em dispositivos para capacitores, termistores, entre outros. A dopagem do BaTiO3 com íons doadores implica na mudança de algumas propriedades físicas, que conduzem a comportamentos anómalos em determinados parâmetros físicos, cuja natureza ainda não tem sido muito esclarecida, embora muitos trabalhos tenham se empenhado para tentar justificar tais efeitos. Neste contexto, neste trabalho, as propriedades físicas do sistema BaTiO3 serão investigadas considerando a adição de elementos doadores, nos sítios A e B da estrutura. Em particular, os íons de gadolínio (Gd3+) e nióbio (Nb5+) serão usados como modificadores da estrutura perovskita em substituição dos íons de bário (Ba2+) e titânio (Ti4+) nos sítios A e B, respectivamente, considerando as fórmulas químicas Ba1-xGdxTiO3 e BaTi1-x NbxO3 (sendo x = 0.001, 0.002, 0.003, 0.004 e 0.005). As propriedades estruturais e microestruturais foram investigadas à temperatura ambiente, enquanto as propriedades dielétricas e elétricas f... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Debnath, Dibyendu Debnath. « SYNTHESIS AND VISCOELASTIC PROPERTIES OF GELS OBTAINED FROM LINEAR AND BRANCHED POLYMERS ». University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525398351097978.
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Morais, Dabney S?rgio Guedes de. « An?lise das propriedades termof?sicas, mec?nicas e geom?tricas de telhas cer?micas queimadas em forno caieira e forno ab?bada ». Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15637.
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Previous issue date: 2011-03-31In the industry of ceramic in Rio G. do Norte, tile stands out as the most manufactured product by this industry, being the intermittent kiln ab?bada and caieira the principal type of kiln used in burning. There was a need to make a study of the influence exerted by the type of kiln in which tiles are burnt in their thermo physical properties. The analysis started with 24 raw samples of tile, which was split in two groups of 12 samples and burnt in Ab?bada and Caieira kiln. Besides that, it was made study of the tax of heat transfer to the environment (for each kiln). After having been burnt the samples were taken for laboratory analysis. The properties verified were impermeability, determination of dry mass, absorption of water, the load of bending rupture and its geometric characteristics, the tests were conducted following the currents standards. The tests were carried out according to the ABNT - NBR 15310. The calculation of the rate of heat transfer showed that the ab?bada kiln is more efficient than the Caieira, however the results of tests on the samples revealed no superiority of one over another sample. So the furnace had no influence on the performance of the ceramic tiles
Na ind?stria de cer?mica vermelha a telha desponta como o produto mais fabricado pela ind?stria de cer?mica do Serid?/RN, sendo os fornos intermitentes do tipo ab?bada e caieira os mais utilizados para a queima destas telhas. Verificou-se a necessidade de se fazer um estudo da influ?ncia exercida pelo tipo de forno no qual as telhas s?o queimadas nas suas propriedades termof?sicas, mec?nicas e geom?tricas. Sendo selecionadas 24 amostras de um mesmo processo de fabrica??o, no entanto estas foram posteriormente separadas em dois lotes de 12 unidades e levadas a queima no forno caieira e ab?bada. ? importante ressaltar que os corpos de prova n?o fazem parte do processo produtivo das cer?micas de onde foram utilizados os fornos para queima, ou seja, as cer?micas gentilmente cederam seus fornos para a realiza??o do experimento. Foi realizado um estudo da taxa de transfer?ncia de calor ao meio ambiente para cada tipo de forno. Assim as amostras ap?s serem queimadas foram levadas para an?lise em laborat?rio. As propriedades verificadas foram ? impermeabilidade, determina??o da massa seca e da absor??o da ?gua, determina??o da carga de ruptura ? flex?o e de suas caracter?sticas geom?tricas. Os ensaios foram realizados segundo a norma ABNT - NBR 15310. O calculo da taxa de transfer?ncia de calor mostrou que o forno ab?bada ? mais eficiente que o caieira, no entanto os resultados dos ensaios nas amostras mostraram que n?o houve superioridade de uma amostra sobre outra, assim os fornos n?o tiveram influ?ncia no desempenho das telhas
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Alshali, Ruwaida. « Characterization of bulk-fill and conventional light-cured resin-composites in terms of composition and polymer matrix properties ». Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/characterization-of-bulkfill-and-conventional-lightcured-resincomposites-in-terms-of-composition-and-polymer-matrix-properties(d85d7616-35e5-4a04-a5b3-20458de1e11d).html.
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Resin-composites have been used in dentistry as direct restorative materials for over fifty years ago, and meanwhile their properties have been substantially improved. Recently a new class of light-cured resin-composites known as 'bulk-fill' materials has been introduced, and has increased the practical application of resin-composites in comparison to conventional incrementally applied materials. The aim of the present research was to assess bulk-fill resin-composites in comparison to conventional materials with respect to their composition, polymeric structure properties and hygroscopic behaviour in oral and food simulating substances. A variety of bulk-fill and conventional resin-composites were tested in this study. Monomer composition of materials has been qualitatively and quantitatively determined using high performance liquid chromatography and mass spectroscopy, and their degree of conversion assessed using Fourier transform infrared spectroscopy. It was found that the degree of conversion of the bulk-fill resin-composites was generally comparable to that of conventional materials and appeared to be governed by the type and quantity of monomers comprising the resin matrix. To evaluate the cross-link density of the polymer matrix, the extent of post-irradiation hardness development, chemical softening, and thermal stability were assessed using microhardness and thermogravimetric analysis. Materials showed variable results and it was suggested that two networks were present in the polymerized resin matrix, a primary network forming immediately after curing followed by a secondary network. The secondary network seemed to have poor cross-link density with low resistance to the degradative effects of solvents. Monomer elution from cured materials was assessed using High performance liquid chromatography over three months' storage in three different media. Elution from bulk-fill resin-composites was found to be comparable to that of conventional materials, despite their increased incremental thickness, with remarkably minimal elution taking place from two bulk-fill materials examined. Monomer elution was shown to be highly dependent on the hydrophobicity of the base monomers and the network characteristics of the resin-matrix. UDMA-BisEMA based systems appeared to be more vulnerable in organic solutions than BisGMA and BisGMA-BisEMA based systems in terms of monomer elution. Sorption and solubility were assessed after one years' storage in water and artificial saliva. Water sorption and solubility of resin-composites were material-dependent and highly affected by the filler loading and initial degree of conversion of the polymeric matrix. BisEMA and UDMA-BisEMA based polymer networks appeared to be more hydrophobic and resistant to sorption and solubility than BisGMA based systems in water based media. The bulk-fill and conventional resin-composites tested were considered stable in the long-term water storage, with the exception of one conventional flowable material.
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Ellena, Rachel A. « Antimicrobial and lipid binding properties of the C-terminal domain of apolipoprotein A-I determined using a novel apolipophorin III/apolipoprotein A-I (179-243) chimera ». Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10144827.
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Apolipoprotein A-I (apoA-I) is an exchangeable apolipoprotein that constitutes the major protein component of high density cholesterol. ApoA-I is a two-domain protein comprising an N-terminal helix bundle and a less-structured C-terminal domain in the lipid-free state. In the present study, the contribution of the C-terminal domain to the lipid binding and antimicrobial activity of apoA-I was investigated using a chimeric construct in which the C-terminal domain of apoA-I (179-243) was attached to an insect apolipoprotein, Locusta migratoria apolipophorin III (apoLp-III), bearing cysteine substitutions for residues 20 and 149. Circular dichroism results were consistent with the addition of a poorly structured domain to apoLp-III and revealed the apoLp-III helix bundle was successfully closed under oxidizing conditions. Electrophoresis, fluorescence spectroscopy and an in vitro study using macrophage cells revealed that the C-terminal domain in itself was insufficient for efficient binding to lipid, lipopolysaccharide and phosphatidylglycerol vesicles. These results suggest the underlying mechanisms governing these interactions are potentiated by cooperativity between the N- and C-terminal domains of apoA-I.
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Bao, Cuimin. « Étude sur la définition du terme "amorphe" par l'analyse comparative de rubans de Pd82 Si18 en termes de production, structure, microstructure, qualité et propriétés mécaniques ». Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL068N/document.
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Depuis leur découverte, un travail de recherche important a été développé sur la production, la structure, la microstructure, les propriétés et les applications des alliages métalliques amorphes. Cependant, la question de ce qui est entendu exactement par le terme « amorphe » n’est pas considérée dans la majorité des études publiées. Or, il n’existe pas de verres réels représentant un désordre parfait comme il n’existe pas de cristaux réels avec une structure parfaitement ordonnée. Il est difficile de donner une définition précise sans donner les limites d’échelle et la technique de détection de cette non-cristallinité. L’étude est une interrogation, pour un alliage particulier, sur le terme « amorphe » en fonction de l’échelle et de la technique. Cette étude comporte une analyse des conditions de préparation d’échantillons amorphes de mêmes compositions. Des techniques complémentaires de détection de leurs différences, en particulier à l’échelle de la structure et de la microstructure ont été utilisées. Des échantillons Pd82Si18 d’épaisseurs différentes ont été produits par solidification ultra rapide sur roue, avec différents paramètres, tels que la vitesse de rotation de la roue, la pression du gaz d’éjection, les dimensions de l’orifice d’éjection, la température de trempe et l’existence ou non d’un traitement thermique du liquide avant la trempe, etc. Les échantillons ont été ensuite analysés avec plusieurs techniques, telles que la diffraction des rayons X et des neutrons, la diffusion des neutrons aux petits angles, la microscopie électronique à transmission, la calorimétrie, les essais mécaniques, la fractographie par microscopie électronique à balayageSince their discovery, an important research work has been developed on the production, the structure, the microstructure, the properties and the applications of amorphous metallic alloys. However, the question of what is exactly meant by the term “amorphous” is not considered in most of the reported studies. As a matter of fact, there exist no real glasses representing a perfect disorder, as there exist no real crystals with a perfectly ordered structure. It is thus difficult to give a precise definition without giving the limitations in scale and in detection of this non-crystallinity. The aim the study is an interrogation, in the case of a specific alloy, on the term “amorphous” as a function of the two directions of reference given above (the scale and the technique). This study thus contains an analysis of the conditions of synthesis of amorphous samples of similar compositions. Furthermore, complementary detection techniques of their differences at the scale of the structure and microstructure have been used. Samples of Pd82Si18 of different thickness have been produced by melt-spinning with different parameters, such as the rotation speed of the wheel, the pressure of the gas, the dimensions of the nozzle, the quenching temperature and the existence or not of a heat treatment of the melt before quench. The samples have been analysed by various techniques such as diffraction of standard X rays and of neutrons, small angle neutrons scattering, transmission electron microscopy, calorimetry, mechanical tests and fractography by scanning electron microscopy
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Garcia, André Gonçalves. « Estudo da influência do superaquecimento nas propriedades mecânicas de uma liga de magnésio contendo terras raras ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/76153.
Texte intégralRésumé :
A demanda por aumento da eficiência energética vem obrigando empresas e centros de pesquisa a desenvolver e utilizar novos materiais buscando a redução de peso. Entre esses materiais, destacam-se as ligas de magnésio, com aproximadamente dois terços da densidade do alumínio e a melhor relação peso/resistência entre os metais. Porém, a utilização do magnésio em altas temperaturas tem suas limitações, devido à baixa resistência a fluência e a formação do precipitado -Mg17Al12 que tem baixo ponto de fusão, tornando as ligas de magnésio mais suscetíveis aos efeitos de deslizamento nos contornos de grãos. Algumas ligas de magnésio contendo elementos terras raras foram desenvolvidas para melhorar a resistência a fluência. O trabalho em questão visa analisar o comportamento da liga Mg6Al3La1Ca, correlacionando os parâmetros de solidificação com as propriedades mecânicas: dureza, alongamento específico, limite de escoamento e limite de resistência à tração. Para isso, foram solidificados unidirecionalmente, com atmosfera de argônio, três lingotes da liga Mg6Al3La1Ca a partir de sobreaquecimento de 780°C, 715°C e 650°C. O resfriamento dos lingotes ocorreu no forno e por resfriamento forçado. Os resultados obtidos de limite de resistência à tração, limite de escoamento e dureza tem uma relação direta com a temperatura de vazamento onde os melhores resultados foram obtidos com as temperaturas mais elevadas. Portanto, conclui-se que na temperatura de 780°C com resfriamento forçado foram obtidas as melhores propriedades mecânicas.The demand for increased energy efficiency is forcing companies and research centers to develop and use new materials aimed at reducing weight. Among these materials, there is magnesium alloys, because it has about two-thirds of the density of aluminum and the best weight/resistance between the metals. However, the use of magnesium at elevated temperatures has its limitations due to low resistance to creep; the formation of -Mg17Al12 precipitate which has a low melting point makes the magnesium alloy more susceptible to slip around the grains. Some magnesium alloys containing rare earth elements have been developed to improve resistance to creep. The work in question is to analyze the behavior the Mg6Al3La1Ca alloy, correlating the parameters of solidification with the mechanical properties: hardness, specific elongation, limits yield strength and tensile strength. For that, three ingots of the alloy Mg6Al3La1Ca were solidified unidirectionally using argon atmosphere with overheating of 780°C, 715°C and 650°C. The cooling of ingots occurred in the furnace and by forced cooling. The results of limit tensile strength, yield strength and hardness have a direct relation with the pouring temperature where the best results were obtained with higher temperatures. Therefore, it is concluded that the best mechanical properties were obtained at temperature of 780°C with forced cooling.
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Bittar, Eduardo Matzenbacher. « Estudo das propriedades magnéticas de novos compostos intermetálicos de terras raras ». [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278506.
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Orientador: Pascoal Jose Giglio PagliusoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Primeiramente sintetizados por Remeika et al., para M = Rh, em 1980, os compostos intermetálicos ternários do tipo R3M4S n13, onde R = íon de terra rara e M = metal de transição (por exemplo, Rh, Ir e Co), cristalizam-se em uma estrutura cúbica. Apesar de possuírem uma estrutura cristalina relativamente simples, esses sistemas apresentam uma série de propriedades físicas interessantes que resultam da combinação de interações microscópicas fundamentais tais como: interaçãoes magnéticas tipo RKKY (Ruderman-Kittel-Kasuya-Yosida), efeitos de campo cristalino, acoplamento elétron-fónon e efeito Kondo. Dentro dessas séries, podemos encontrar, por exemplo, materiais supercondutores, férmions pesados, metais com ordenamentos magnéticos e paramagnéticos. Neste trabalho descrevemos o processo de síntese e as propriedades físicas para a série inédita com M = Co, que apesar de possuir suas estruturas catalogadas, jamais teve suas propriedades físicas reportadas (ao menos que tenhamos conhecimento). Monocristais de R3Co4Sn13, onde R = La, Ce, Pr, Nd e Gd, foram crescidos pela técnica de fluxo metálico. A estrutura cristalina desses compostos intermetálicos foi determinada por difração de raios X. Eles se cristalizam em uma estrutura cúbica tipo Yb3Rh4Sn13, grupo espacial Pm-3n, que apresenta 40 átomos por célula unitária. Medidas de susceptibilidade magnética, calor específico e resistividade elétrica foram realizadas nesses monocristais. Esses compostos ordenam-se antiferromagneticamente em baixas temperaturas (TN < 15 K) para R = Nd e Gd, enquanto o Pr3Co4Sn13 é paramagnético até 2 K. O composto de Ce3Co4Sn13 apresenta um comportamento tipo férmion pesado e o La3Co4Sn13 é um paramagneto de Pauli que sofre uma transição supercondutora em 2,3 K. Através de um modelo de campo médio (desenvolvido por colaboradores) que considera interações magnéticas entre primeiros vizinhos e efeitos de campo cristalino cúbico, ajustou-se simultaneamente as curvas de susceptibilidade magnética e calor específico obtendo-se os parâmetros A4 e A6 que caracterizam o potencial do campo cristalino cúbico para a série de intermetálicos R3Co4Sn13. Observou-se que estes parâmetros independem da terra rara, sofrendo variação apenas para o composto de Ce
Abstract: Firstly synthesized by Remeika et al., for M = Rh, in 1980, the intermetallic compounds R3M4Sn13, where R = rare-earth ion and M = transition-metal (for exemple, Rh, Ir and Co), crystallizes with a cubic structure. These compounds include, for instance, superconducting materials, heavy-fermions, magnetic materials and paramagnetic metals. Complex magnetic ordering, crystalline electrical field effects (CEF) and Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetic interaction are interesting physical phenomenal found in systems of these family, despite of their simple cubic structure. These facts make this series an excellent class of compounds to explore the interplay between these physical properties. In this work we describe the synthesis process and the physical properties of a novel serie of R3M4Sn13 for M = Co and R = La, Ce, Pr, Nd and Gd. R3Co4Sn13 single crystals were grown from metallic flux. Measurements of X-ray diffraction, magnetic susceptibility, heat capacity and electrical resistivity were performed. They crystallize in a cubic Yb3Rh4Sn13 type structure, space group Pm-3n, which has 40 atoms per unit cell. These compounds order antiferromagnetically at low temperature (TN < 15 K) for R = Nd and Gd, while Pr3Co4S n13 is paramagnetic down to 2K. The Ce3C o4Sn13 compound display heavy fermion behavior at low temperature and La3Co4Sn13 is a Pauli paramagnetic which superconducts at 2.3 K. With a mean field model (developed by collaborators) which considers magnetic interactions for the first neighbors and a cubic CEF, we fit simultaneously the magnetic susceptibility and heat capacity data obtaining the CEF parameters A4 and A6 that characterize the CEF potential for the R3Co4Sn13 intermetallic series. We observed that theses parameters are rare-earth independents, being the Ce-base compound the only exception
Mestrado
Física da Matéria Condensada
Mestre em Física
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Romero, Sérgio Antônio. « Microestrutura e propriedades magnéticas de ligas para ímãs nanocristalinos de Sm(CoFeCuZr)z para aplicações em altas temperaturas ». Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-19072013-162250/.
Texte intégralRésumé :
O objetivo deste trabalho foi tentar correlacionar microestrutura e propriedades magnéticas de ímãs permanentes de alta energia do tipo Sm(CoFeCuZr)z para aplicações em temperaturas acima de 300°C. Avaliou-se a possibilidade de que o constituinte matriz da microestrutura dos ímãs para altas temperaturas fosse diferente do constituinte matriz dos ímãs convencionais. Com este propósito foram estudados três conjuntos de amostras: i) Dois ímãs comerciais para aplicações na temperatura ambiente, um da Electron Energy e outro da Vacuumschmelze. Eles foram caracterizados magneticamente e a sua microestrutura foi analisada por microscópio eletrônico de varredura dotado de análise química, com o objetivo de avaliar se os mesmos apresentavam dois microconstituintes presentes em algumas ligas de Sm(CoFeCuZr)z. ii) Uma liga comercial da Johnson Matthey (JM) que é utilizada para produzir ímãs permanentes de Sm(CoFeCuZr)z. Essa liga foi utilizada para o estudo e avaliação de ciclos térmicos como solubilização, tratamento isotérmico, rampa de resfriamento lento e tratamento térmico a 400°C, e o seu efeito nas propriedades magnéticas e na micro e nano estruturas. iii) Duas séries de ligas com seis amostras cada série produzidas em forno a arco voltaico no LMM-IFUSP, com o propósito de estudar o efeito do teor de cobre e samário nas propriedades magnéticas, na microestrutura e na nanoestrutura dessas ligas. A caracterização magnética em campo de 9T permitiu determinar a polarização máxima e o campo coercivo das amostras. A caracterização magnética em campos de até 2T permitiu determinar o campo coercivo e a polarização remanente das amostras em temperaturas na faixa de 200 a 500°C. Três ligas resultaram em campo coercivo Hci > 398kA/m (Hci > 5kOe) a 450°C, que segundo a literatura, podem ser utilizadas em aplicações em temperaturas elevadas. Uma caracterização detalhada da microestrutura e da composição química foi feita utilizando-se Microscopia Eletrônica de Varredura (MEV) com VI análise química de praticamente todas as amostras. No diagrama de fases pseudo-ternário foi possível definir o campo de fases das composições 2:17R com baixo e alto Sm. As amostras da liga comercial JM e três das doze ligas produzidas em forno a arco voltaico apresentaram os microconstituintes claro e escuro e estes parecem não afetar as propriedades magnéticas das amostras. Foi observado que com o aumento do teor de Sm na liga a polarização máxima diminui. A polarização máxima Jmáx também diminui com o aumento do teor de Cu na liga, porém de forma menos acentuada. Foi possível observar a estrutura nanométrica, bem como a presença e a formação das nanocélulas nessas ligas nanocristalinas com elétrons secundários via microscopia eletrônica de varredura com fonte de emissão de campo MEV/FEG, que é um diferencial neste trabalho uma vez que essas análises são típicas em microscopia eletrônica de transmissão. Verificou-se que as nanocélulas são observáveis com FEG em amostras cuja coercividade são superiores a 159 kA/m (2kOe). Foi possível aplicar o modelo de Stoner-Wohlfarth modificado por Callen Liu e Cullen à curva de histerese para determinar o campo de anisotropia magnetocristalina, a magnetização de saturação e o coeficiente de interação de campo médio 1/d. A difração de Raios-X aliada ao refinamento Rietveld permitiram determinar as fases formadas em altas temperaturas após o tratamento de homogeneização a 1175°C/4h. Verificou-se que há a formação de duas fases romboédricas, uma rica em cobre e a outra rica em ferro. Este dado é inédito na literatura.The main objective of this study was to correlate microstructure and magnetic properties of high-energy permanent magnets of the Sm(CoFeCuZr)z type for applications at temperatures above 300°C. The possibility that the matrix constituents of the microstructure of high temperature magnets are different from the matrix constituents of the conventional magnets is investigated with three sets of samples: i) Two magnets for commercial applications at room temperature, one produced by Electron Energy and the other by Vacuumschmelze. ii) A Sm(CoFeCuZr)z as-cast alloy synthesized by Johnson Matthey (JM) for permanent magnets production was used to study the effect of heat treatment steps as follows: (a) solutionizing at 1175°C for 4h, b) followed by quenching in water, (c) reheating at 820°C for 7h, d) followed by slow cooling down at 1°C/min to 400°C, and (e) heat treatment at 400°C for different durations and their effects on its magnetic properties and its micro and nanostructure. iii) Two series of Sm(CobalFe0.15CuxZr0.023)7 and Sm(CobalFe0.15CuxZr0.023)8.5 alloys with x=0.058, 0.088, 0.108 were prepared by arc melting technique, in order to study the effect of Copper and Samarium contents on its microstructure and magnetic properties. The characterization in magnetic fields up to 9T allowed to determine the maximum polarization and the intrinsic coercivity of the samples. The characterization in magnetic field up 2T allowed to determine the coercive field and remanence of the samples at temperatures between 200°C and 500°C. Three alloys resulted in coercive field Hci > 398kA/m (Hci > 5kOe) at 450°C, which according to the literature, can be used in applications at elevated temperatures. A detailed characterization of the microstructure and chemical composition was performed using scanning electron microscopy (SEM) with EDAX chemical analysis of virtually all samples. The JM samples and three of the twelve alloys produced in the electric arc furnace showed the light and dark microconstituents, here identified as two 2:17 rombohedral phases with low and VIII high Sm. In a pseudo-ternary phase diagram it was possible to define the two phase field of 2:17R with low and high Sm. No correlation could be found with the magnetic properties of the samples. It was observed that by increasing the Sm content in the alloy the maximum induction Jmax decreases. The maximum induction Jmax also decreases with increasing Cu content in the alloy, but to a lesser extent. It was possible to observe the nanocrystalline microstructure as well as the presence and formation of nanocrystalline cells with scanning electron microscopy with field emission source SEM-FEG. Those characteristics are usually only observed by transmission electron microscopy. It was found that the nanocrystalline cells are observable with SEM-FEG on samples whose coercivity is above 159 kA/m (2kOe). It was possible to apply the Stoner-Wohlfarth model modified by Callen Liu and Cullen in the hysteresis loop to determine the magnetocrystalline anisotropy field, the saturation magnetization and the mean field interaction 1/d. The X-ray diffraction coupled with a Rietveld refinement were used to determine the phases formed at high temperatures after the solutinizing heat treatment at 1175°C/4h. It was found that there are two kinds of 2:17 rhombohedral phases formation. One is rich in copper and the other rich in iron.
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Oliveira, Neto Manoel Leonel de. « Estudo do aproveitamento de res?duo de gesso como carga para comp?sito com matriz de resina expansiva de mamona ». Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15586.
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Previous issue date: 2012-02-16In the execution of civil engineering works, either by wasting during the coating of wall or demolition of gypsum walls, the generation of the gypsum waste involves serious environmental concerns. These concerns are increased by the high demand of this raw material in the sector and by the difficulties of proper disposal byproduct generated. In the search for alternatives to minimize this problem, many research works are being conducted, giving emphasis in using gypsum waste as fillers in composites materials in order to improve the acoustic, thermal and mechanical performances. Through empirical testing, it was observed that the crystallization water contained in the residue (CaSO4.2H2O) could act like primary agent in the expanding of the polyurethane foam. Considering that polyurethane produced from vegetable oils are biodegradable synthetic polymers and that are admittedly to represent an alternative to petrochemical synthetic polyurethane, this research consist an analysis of the thermal behavior of a composite whose matrix obtained from a resin derived from the expansive castor oil seed, with loads of 4%, 8%, 12% and 16% of gypsum waste replacing to the polyol prepolymer blend. Contributors to this analysis: a characterization of the raw material through analysis of spectroscopy by Fourier transform infrared (FTIR), chemical analysis by X-Ray Fluorescence (XRF) and mineralogical analysis by X Ray Diffraction (XRD), complemented by thermo gravimetric analysis (TGA). In order to evaluate the thermo physical properties and thermal behavior of the composites manufactured in die closed with expansion contained, were also carried tests to determine the percentage of open pore volume using a gas pycnometer, scanning electronic microscopy (SEM), in addition to testing of flammability and the resistance to contact with hot surfaces. Through the analysis of the results, it appears that it is possible to produce a new material, which few changes in their thermo physical properties and thermal performance, promotes significant changes and attractive to the environment
Na execu??o de obras na constru??o civil, seja por desperd?cio de gesso durante o revestimento de paredes ou na demoli??o de paredes de gesso acartonado, a gera??o do res?duo implica em preocupa??es ambientais decorrentes da alta demanda dessa mat?ria prima no setor e da dificuldade de destina??o adequada ao subproduto gerado. Na busca por uma alternativa que atenue o problema, muitas pesquisas t?m sido realizadas com ?nfase na utiliza??o do res?duo de gesso como carga em comp?sitos, com o intuito de melhorar os desempenhos ac?stico, t?rmico e mec?nico. Atrav?s de ensaios emp?ricos, observou-se que a ?gua de cristaliza??o contida no res?duo (CaSO4.2H2O) pode atuar como agente prim?rio no processo de expans?o de espumas de poliuretano. Considerando que os poliuretanos, derivados de ?leos vegetais, s?o pol?meros sint?ticos biodegrad?veis e que, reconhecidamente, representam uma alternativa aos poliuretanos sint?ticos petroqu?micos, a presente pesquisa procura fazer uma an?lise do comportamento t?rmico de um comp?sito desenvolvido com matriz de resina vegetal derivada do ?leo de mamona, com cargas de 4%, 8%, 12% e 16% de res?duo de gesso em substitui??o ? mistura poliol + pr?-pol?mero. Contribu?ram para esta an?lise: caracteriza??o da mat?ria prima por meio de espectroscopia de absor??o na regi?o do infravermelho por transformada de Fourier (FTIR), an?lise qu?mica por FRX e mineral por DRX e an?lise termogravim?trica (TGA e DTA). Com o prop?sito de avaliar as propriedades termof?sicas e o comportamento t?rmico dos comp?sitos produzidos com expans?o contida por fechamento do molde. Tamb?m foram realizados ensaios para determina??o do percentual de poros abertos, por meio de picn?metro a g?s, morfologia dos comp?sitos (MEV), al?m de ensaios de inflamabilidade e de resist?ncia ao contato com superf?cies aquecidas. Mediante a an?lise dos resultados obtidos, constatou-se a possibilidade de produ??o de um novo material para isola??o t?rmica, apresentando poucas altera??es em suas propriedades Termof?sicas, assim como em seu desempenho t?rmico, promovendo altera??es significativas e atraentes ao meio ambiente
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Buzolin, Ricardo Henrique. « Mechanical properties and corrosion behaviours of the as-cast ZK40 alloys modified with individual additions of CaO, Gd, Nd and Y ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-13012017-093623/.
Texte intégralRésumé :
The effect of individual additions of calcium oxide (CaO), Gd, Nd and Y was investigated on the microstructure, mechanical properties and corrosion resistance of the as-cast ZK40 alloy. The microstructural features were analised using optical, scanning and transmission electron microscopy, X-ray diffraction and Scanning Kelvin Atomic Probe Force Microscopy. The compressive and tensile behaviours of the as-cast alloys at room temperature were investigated. Electrochemical Impedance Spectroscopy, hydrogen evolution and weight loss under immersion in 0.5 wt.% NaCl solution were used to evaluate the corrosion behaviour. The results of the mechanical and corrosion tests were correlated with the microstructures. The 2 wt.% Gd addition enhanced the ductility, while the Nd addition resulted in deterioration in mechanical properties. The addition of 2 wt.% Gd and 1 wt.% Y resulted in the improvement of the ductility. The addition of CaO did not affect the mechanical properties while the 2 wt.% Nd deteriorate it. The 1 wt.% Y addition enhanced the ductility. The CaO addition did not caused enhancement in mechanical properties. The corrosion behaviour was enhanced with the addition of CaO and Gd. The modification of ZK40 with Gd opens up new perspectives in the development of Mg-Zn based alloys.O efeito da adição individual de óxido de cálcio (CaO), Gd, Nd e Y foi investigado na microestrutura, propriedades mecânicas e resistência à corrosão de ligas ZK40 fundidas. As características microestruturais foram analisadas via microscopia óptica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de Raios-X e \"Scanning Kelvin Atomic Probe Force Microscopy\". O comportamento à compressão e à tração das ligas à temperatura ambiente foi investigado. Espectroscopia eletroquímica de impedância, evolução de hidrogênio e ensaios de imersão em solução de 0.5% em peso de NaCl foram utilizados para avaliar a resistência à corrosão. Os resultados dos ensaios mecânicos e corrosão foram relacionados com a microestrutura. A adição de 2% em peso de Gd melhorou a ductilidade, ao passo que a adição de Nd resultou na piora das propriedades mecânicas. A adição de 2% em peso de Gd e 1% em peso de Y resultou na melhora da ductilidade. A adição de 1% em peso de Y causou uma melhora na ductilidade e a adição de CaO não teve impacto benéfico nas propriedades mecânicas. A resistência à corrosão foi melhorada com a adição de CaO e Gd. A modificação da liga ZK40 com a adição de Gd abre novas perspectivas no desenvolvimento de ligas Mg-Zn.
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Laguardia, Rafael Martins de Oliveira. « Sorte de terra, fazenda, sesmaria... georreferenciamento como instrumento de análise do registro de terra ». Universidade Federal de Juiz de Fora (UFJF), 2011. https://repositorio.ufjf.br/jspui/handle/ufjf/2435.
Texte intégralRésumé :
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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Esta dissertação faz uma análise dos Registros Paroquiais de Terras de Santo Antonio do Paraibuna, atual município de Juiz de Fora e alguns distritos e cidades vizinhas, desenvolvendo um método de gerar mapas através de suas informações. Dessa forma, tem como objetivo: Representar parte da estrutura fundiária da antiga vila de Santo Antonio do Paraibuna por meio da modelagem da representação espacial das propriedades, principalmente as rurais. A ‘Distribuição Espacial’ produzida constituirá além de um instrumento de análise semiótica, um sistema de informações e resultará em nova metodologia para a História e, principalmente, para a História Agrária. A partir de uma leitura qualitativa, visando sua decodificação através de uma análise detalhada, e quantitativa das fontes que, neste caso, serão originários dos Registros Paroquiais de Terras e de seu cruzamento será possível identificar e possibilitar esta distribuição espacial das propriedades e representá-las em um instante de tempo. Após a espacialização, ou seja, a distribuição espacial buscar-se-á realizar a ‘Redistribuição Dimensionada’, isto é, realizar novamente a distribuição espacial acrescentando informações referentes à dimensão das propriedades. E, legitimar mutuamente, uma metodologia nova para o tratamento de uma fonte histórica com a composição parcial da estrutura fundiária de Santo Antonio do Paraibuna, em um estudo de caso. Tal metodologia busca sistematizar na forma de um “quadro sinóptico” um tema: Propriedades Rurais. O desenvolvimento de uma metodologia nova implica em um alargamento das possibilidades de pesquisas historiográficas e neste caso um uso a mais para as informações históricas oriundas do Registro de Terras. Tudo isto reafirma, para a pesquisa histórica, a importância de considerar e pensar a pesquisa dentro da relação tempo-espaço como um continuum, em um campo de variáveis qualquer, tal como são as propriedades rurais. Como em qualquer modelo, não se tem a pretensão de corresponder Ipsis litteris à realidade, principalmente esta que não existe mais, parte-se de uma modelagem matemática para alcançar a ideia de proporcionalidade entre propriedades nesta estrutura fundiária. Resulta em um método capaz de criar ferramentas na forma de um mapa reutilizáveis para novas avaliações históricas, tal como uma nova fonte histórica acrescida de novas informações, como as geográficas, e a recomposição da informação da fonte histórica. Conclui-se que é oportuna a inserção do Georreferenciamento nas pesquisas historiográficas, pois são notórias suas potencialidades na pesquisa.
This work is an analysis of the Registros Paroquiais de Terras of Santo Antônio do Paraibuna, current city of Juiz de Fora and some neighboring districts and cities, developing a method of generating a spatial distribution of properties through its information. Thus, it aims to: i) represent part of the land structure of the old town of Santo Antonio do Paraibuna by modeling the spatial representation of the properties, mainly the rural ones. The produced 'Spatial Distribution' will constitute an instrument of semiotic analysis and also an information system. This will lead to new methodology for the History and, especially, to the Agricultural History. From a qualitative reading, aiming its decoding through a detailed and quantitative analysis of the sources that, in this case, will have their origins in the Registros Paroquiais de Terras and their intersection. From this, it will be possible to identify and allow this spatial distribution of properties and represent them in an instant of time. After the spatial, ie, the spatial distribution will seek to perform the ‘Sized Redistribution’, ie, to perform again the Sized Distribution, adding to it information on the size of the properties. ii) to legitimize each other, a new methodology for the treatment of a historical source with the partial composition of the land structure of Santo Antonio do Paraibuna, in a case study. This methodology seeks to systematize in the form of a "summary table" a theme: Rural Properties. The development of a new methodology involves a greater scope for historical research and, in this case, one use more for the historical information derived from Registro de Terras. All this confirms, for historical research, the importance of considering and thinking about research into the relationship as a time-space continuum, in a field of any variables, as are the rural properties. As any model, we do not intend to match Ipsis litteris the reality, mainly that which no longer exists, it starts from a mathematical model to achieve the idea of proportionality between properties in this land structure. It results in a method capable of creating reusable tools in the form of a map for new historical evaluations, such as a new historical source added of new information, such as geographical, and the restoration of the information of the historical source. We conclude that the inclusion is timely in the Georeferencing in the historiographical research because their potentialities are notorious in research.
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Monteiro, José Carlos Botelho 1984. « Medidas diretas do efeito magnetocalórico convencional e anisotrópico por medida do fluxo de calor com dispositivos Peltier ». [s.n.], 2016. http://repositorio.unicamp.br/jspui/handle/REPOSIP/305750.
Texte intégralRésumé :
Orientador: Flávio César Guimarães GandraTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Esta tese tem como principal objetivo desenvolver, apresentar e justificar a utilização de uma metodologia experimental que permita avaliar o efeito magnetocalórico (EMC), em qualquer tipo de material, de modo que as medidas reflitam a resposta real que a amostra fornece ao ser submetida a ciclos de magnetização similares àqueles que ocorrem em sistemas de refrigeração magnética. Para tal, construímos sistemas de medidas que utilizam dispositivos Peltier como sensores de fluxo de calor, capazes de realizar medidas diretas da quantidade de calor que a amostra absorve ou libera em situações aonde há variação de temperatura, campo magnético ou do ângulo entre direção do cristal e o campo aplicado. Na primeira parte do trabalho, foram realizadas medidas no sistema com dispositivos Peltier desenvolvido para uso no equipamento comercial PPMS - Physical Property Measurement System (Sistema de medidas de propriedades físicas) da Quantum Design. Utilizamos os métodos indiretos de medida do EMC mais comuns na literatura (medidas via curvas de magnetização e calor específico) para comparação com as medidas diretas de fluxo de calor através de varredura de campo obtidas pelo nosso sistema. Esta análise foi feita inicialmente em duas amostras com transições magnéticas de primeira e segunda ordem, consideradas como amostras padrão na área do EMC: Gadolínio e a liga Gd5Ge2Si2. Discutimos as diferenças encontradas e definimos aquele que acreditamos ser o protocolo de medidas mais correto para a avaliação do EMC para fins práticos. A partir desta conclusão, analisamos três outras amostras que apresentam comportamentos não usuais e alto potencial magnetocalórico e discutimos as diferenças. Perdas do EMC por histerese foram obtidas experimentalmente. Na segunda parte, com o auxílio de um calorímetro com o elemento Peltier capaz de realizar um giro de até 80° sob campo constante de até 1,9 T, realizamos o estudo do efeito magnetocalórico anisotrópico (EMC-ani) em amostras monocristalinas da família RAl2, obtidas pelo processo de Czochralski. Primeiramente medidas de calor específico e do EMC convencional foram realizadas nos monocristais, através do protocolo definido como ideal na primeira parte do trabalho, utilizando o sistema Peltier do PPMS. A partir desses dados, fomos capazes de obter o EMC-ani, de modo indireto, pela subtração das curvas obtidas. Por fim utilizamos o sistema Peltier de giro para realizar medidas diretas do EMC-ani em monocristais de DyAl2. Os resultados das medidas indiretas e diretas foram comparados com cálculos obtidos através de um modelo autoconsistente
Abstract: This thesis aimed to develop, present and justify the use of a methodology that allows one to evaluate the magnetocaloric effect (MCE), for any kind of material, such that the results reflects the real behavior of the sample submitted to magnetization cycles similar to those of magnetic refrigeration systems. To do so, we built measurement systems that uses Peltier devices as heat flux sensors to determine the heat absorbed or released by the sample in situations where the temperature, magnetic field, or angle between a given crystal direction and field changes. In the first part of the work, we report measurements using a Peltier device system developed for use with the Quantum Design PPMS (Physical Property Measurement System). We evaluated the indirect MCE measurements by using the most common techniques found in literature (through magnetization or specific heat curves) and compared to the direct heat flux measurements obtained through field sweep scans with our system. This analysis was initially made with two samples that present a first and a second order magnetic transition, considered as standard samples at MCE research area: Gadolinium and the Gd5Ge2Si2 alloy. We discussed the differences found and defined the measurement protocol that we believe to be correct to the practical evaluation of the MCE. From this conclusion, we analyzed three other samples that present uncommon behavior and high magnetocaloric potential and discussed their differences. MCE hysteresis losses were experimentally obtained. In the second part, with the aid of a calorimeter built with Peltier devices capable of perform an 80° rotation under constant magnetic field up to 1,9 T, we made the study of the Anisotropic Magnetocaloric Effect (MCE-ani) in monocrystalline samples of the RAl2 family grown by the Czochralski method. First, we made specific heat and conventional MCE measurements with the ideal protocol that was defined in the first part of the work, using the PPMS Peltier system. From these data, we were able to calculate indirectly the MCE-ani by subtracting the acquired curves. Finally, we used the Peltier rotation system to perform direct measurements of the MCE-ani in DyAl2 single crystals. The results of the indirect and direct measurements were compared with calculations achieved using a self-consistent process
Doutorado
Física
Doutor em Ciências
1060137/2011
CAPES
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Sanchez, Renato Sartori Lardin. « Avaliação da força de repulsão entre magnetos de neodímeo ferro boro usados em tratamentos intra e extra bucais ». Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/23/23152/tde-08052012-162521/.
Texte intégralRésumé :
Os magnetos de Neodímio Ferro Boro (Nd2Fe14B) apresentam excelentes propriedades magnéticas e compatibilidade biológica, embora sejam frágeis e possuam baixa resistência à corrosão. As forças de atração magnética de magnetos de terras raras têm sido empregadas em sistemas de retenção, principalmente associadas aos implantes osseointegráveis, em próteses bucais e próteses faciais, bem como em aparelhos ortodônticos. Este estudo avalia o comportamento das forças de repulsão magnética, em função do volume e comprimento do eixo magnético, quando submetidos a afastamentos, de modo que esta propriedade física seja empregada em odontologia. Vinte e quatro corpos de prova, com um ou dois pares de magnetos de Nd2Fe14B, com diferentes formas e volumes variados, foram submetidos a ensaio mecânico para mensuração das forças de repulsão magnética, em condições de afastamentos que variaram entre 0,0 e 20,0 mm. Os dados observados mostram que, considerando-se uma mesma área superficial de polo, a força de repulsão magnética varia em função do comprimento do eixo magnético. Os dados relativos ao afastamento foram submetidos a análise de variância (p0,05), tendo-se observado que o aumento da distância entre os magnetos diminui significantemente a força de repulsão magnética na maioria dos corpos de prova. No afastamento 0,0 mm as forças magnéticas de repulsão dos subgrupos mantêm uma sequência crescente a partir do subgrupo de menor volume de magnetos ao subgrupo de maior volume de magnetos, os quais permanecem nessa sequência nos afastamentos iniciais. A força de repulsão magnética gerada por magnetos pequenos varia menos em função do aumento do afastamento. Conclui-se que a variação da força de repulsão magnética, dada a mesma área superficial de polo, apresenta uma relação direta com o volume e com o eixo magnético onde, quanto maior o volume ou o comprimento do eixo magnético, maior a força de repulsão magnética. A relação direta entre volume e força de repulsão magnética não se altera frente aos afastamentos inicais, tendendo a se tornar imensurável com o aumento da distância. A força de repulsão magnética mantém uma relação inversa com a distância entre os pares de magnetos. Este ensaio mecânico indica que a força de repulsão magnética apresenta, assim como a força de atração magnética, uma curva hiperbólica de redução frente ao aumento do afastamento.Neodymium Iron Boron (Nd2Fe14B) magnets exhibit excellent magnetic properties and demonstrate biological compatibility, despite of their fragility and low resistance to corrosion. The magnetic attraction forces of rare earth magnets have been used in retention systems mainly associated with osseointegrated implants, in oral and facial prostheses, as well as orthodontic appliances. This study evaluates the repulsion forces of magnets, varying volume and length of magnetic axis when subjected to vertical distance, in order to assess the usefulness of such physical property in clinical situations. Twenty-four specimens, with one or two pairs of Nd2Fe14B magnets, presenting different shapes and various volumes, were subjected to mechanical testing so as to measure magnetic repulsion forces, under conditions of vertical pole face separation ranging from 0.0 to 20.0 mm. Repulsive magnetic force varies depending on the length of the magnetic axis, when considering the same surface area of a pole. Analysis of Variance - (p0.05) indicated that by increasing the distance between the pairs of magnets, magnetic repulsion force significantly reduces in most of the specimens. Starting at a 0.0 mm distance, the magnetic repulsion forces keep an enhancing sequence from lower to higher magnetic volume, holding these characteristics during initials distances. Repulsion magnetic forces generated by small magnets varies less as the distance increases. The results indicate the repulsion magnetic force variation, fixing the same pole surface area, presenting a direct relationship between volume and magnetic axis, since the increase of the volume or of the magnetic axis length leads to a higher magnetic repulsive force. The relationship between volume and magnetic repulsion force does not vary at initial distance. Nevertheless, when such distance increases, the force between the magnets significantly decreases. The magnetic repulsion force holds an inverse relationship with respect to the distance between magnets pairs. This mechanical test indicates that the magnetic repulsion force, as well the magnetic attraction force, present a hyperbolic curve of force reduction due to the increasing vertical distance.
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Ferreira, Alexandre Amorim de Souza. « A relação entre o tamanho das propriedades agrícolas e a produtividade no Brasil : uma análise não paramétrica ». Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11132/tde-26072018-151256/.
Texte intégralRésumé :
A análise de regressão kernel não paramétrica desconsidera qualquer influência das formas funcionais geralmente empregadas em análises de regressões paramétricas, permitindo os dados \"falarem por si mesmos\". Enquanto os estimadores paramétricos são considerados globais, os kernels não paramétricos usam uma amostra de dados próximas (definida pela largura da janela) a um ponto para ajustar a estimação, o que permite focar em peculiaridades locais dos dados. Ambas as análises foram aplicadas aos dados do Censo Agropecuário de 2006 realizado pelo IBGE, agregados municipalmente e em dezessete faixas de áreas, para estimar uma função de produção com o objetivo de estabelecer a relação entre o tamanho das propriedades agrícolas e o valor da produção por hectare (produtividade). A relação constatada foi inversa, porém a análise local feita pelos estimadores kernels explicitou uma relação direta entre as elasticidades de produção dos insumos e o tamanho das propriedades agrícolas, o que não justifica uma política de redistribuição de terras no sentido do aumento da produtividade. Além disto, análises gráficas contra fatuais (que manteve os insumos, exceto a área, constantes em seus valores médios) mostraram que a relação não é linear, não é monotônica, e difere dentre as regiões, o que é um desafio para a elaboração de políticas de redistribuição de terras.Nonparametric kernel regression analysis disregards any influence of the functional forms commonly employed in parametric regression analyzes, allowing the data to \"speak for itself.\" While parametric estimators are considered global, nonparametric kernels use a sample of nearby data (defined by the bandwidth) at a point to adjust the estimation, which allows focusing on local peculiarities of the data. Both analyzes were applied to data from the 2006 IBGE Census of Agriculture, aggregated in municipalities and in seventeen areas, to estimate a production function with the objective of establishing the relationship between the size of agricultural properties and the value of production by hectare (productivity). The observed relationship was reversed, but the local analysis made by the kernels estimators explained a direct relationship between the elasticities of production of the inputs and the size of the agricultural properties, which does not justify a policy of redistribution of land in order to increase productivity. In addition, graphical analyzes against factors (which kept the inputs, except the area, constant in their mean values) showed that the relationship is not linear, is not monotonic, and differs among regions, which is a challenge for the elaboration of land redistribution policies.
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Rouxinol, Francisco Paulo Marques 1977. « Propriedades magnéticas de filmes de ligas GD-Cr ». [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278407.
Texte intégralRésumé :
Orientador: Mario Antonio Bica de MoraesTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Técnicas de condensação de vapor são úteis na preparação de ligas magnéticas cujos componentes têm pouca, o mesmo nenhuma, solubilidade em condições de equilíbrio Neste trabalho, uma dessas técnicas ¿ sputtering ¿ foi empregada para fabricar ligas metaestáveis de GdXCr1-X, cujas propriedades magnéticas foram investigadas em função da concentração de Gd, x. Difratometria de raios-X de baixo ângulo (GAXRD) e espectroscopia de retroespalhamento Rutherford foram utilizados para determinar a estrutura do filme e sua composição elementar, respectivamente. As análises de GAXRD mostraram que a estrutura da fase de Gd, é hcp quando x ³ 0,88; e amorfa quando 0,16 £ 0,76. Uma estrutura bcc , para a fase de Cr, foi observada nos difratogramas quando x < 0,16, e amorfa quando x ³ 0,16 Para investigar as propriedades magnéticas utilizamos um magnetometro SQUID e m PPMS. O primeiro foi utilizado para as medidas de momento magnético em função do campo estático e temperatura. O PPMS foi tilizado nas investigações de susceptibilidade-AC em função da freqüência de oscilação do campo, temperatura e campo estático. A complexa natureza magnética dos filmes de Gd-Cr foi observada através das isotermas MxH, que não apresentaram saturação em baixas temperaturas, nem comportamento linear em altas temperaturas. Pela análise dos dados magnéticos, observamos que as amostras admitem um comportamento ferromagnético para x ³ 0,5 e paramagnético para as outras concentrações de Gd. A temperatura de Curie (TC) apresenta um aumento monotônico de 170 para 290 K quando x aumenta de 0,5 para 1,0. A temperatura de Curie-Weiss (q C) mostra um aumento monotônico com x. A partir das isotermas MxH a 2 K, o momento de saturação foi calculado, sendo independente de x e aproximadamente constante com um valor médio de 7,3 µB. Medidas de susceptibilidade em campos estáticos e dinâmicos revelaram a existência de comportamentos de vidros magnéticos em todas as amostras abaixo da temperat ra de freezing (Tf). Observamos, nas ligas com altas concentrações de Gd, a presença de comportamentos ferromagnéticos e cluster-glass em baixas temperaturas. Concluímos que a interação de troca entre os átomos de Gd dentro dos clusters de Gd não é do tipo RKKY, e sim do tipo supertroca. O efeito magnetocalórico (MCE) foi investigado através da variação de entropia magnética ( D SM) em função da temperatura, para a remoção de um campo de 50 kOe Curva de D SMxT para as amostras com x < 0,2 apresentaram um formato típico de superferromagneto, consistente com a existência de clusters Gd nos filmes. Nas outras amostras em que o EMC foi analisado, a presença de clusters é observada pelo comportamento dessas curvas a baixa temperatura; a altas temperaturas o comportamento de D SM com T indica fortemente a presença de mais fases magnéticas no filme. O diagrama de fase baseado em TC e Tf, e sua dependência com x é apresentado
Abstract: Vapor condensation techniques are very useful for preparation of alloys whose components have no mutual solubility under equilibrium conditions In this work, one of these techniques ¿ sputtering ¿ has been used to fabricate metastable GdXCr1-X alloys whose magnetic properties were investigated as a function of the Gd concentration, x. Grazing incidence angle X-ray diffraction (GAXRD) and Rutherford backscattering spectroscopy were employed to characterize the film structure and elemental composition, respectively. The GAXRD measurements revealed, for the Gd fraction, a hcp structure for x ³ 0,88; for 0,16 £ x £ 0,76 the Gd fraction was amorphous. The existence of a bcc structure for x < 0,16 was observed in the diffractograms for the Cr phase, which was amorphous for x ³ 0,16. To investigate the magnetic properties, a SQUID magnetometer and a PPMS were used. The former was employed for magnetic moment measurements as a function of applied static field and temperature. The PPMS was used for ac-susceptibility determinations as a function of the frequency of the ac driving field, temperature, and applied static field. The complex magnetic nature of the Gd-Cr films was revealed from the MxH isotherms which did not show saturation even at the lowest temperatures, and did not exhibit a linear behavior at higher temperatures. Processing of the magnetic data has shown that the films exhibit a ferromagnetic behavior for x ³ 0,5 and paramagnetic one for all other Gd concentrations. The Curie temperature (TC) increased monotonically from 170 to 290 K as x increased from 0,5 to 1,0. A monotonical increase in the Curie-Weiss temperature ( q C ) with x was also observed for all films. From the extrapolated MxH isotherm at 2 K (saturation magnetization), the saturation moments were calculated and found to be nearly constant at about 7.3 µB. Both static and dynamic susceptibility measurements revealed the existence of a magnetic glassy behavior in all alloys, occurring below a freezing temperature Tf . For the higher concentration alloys, the ferromagnetic and the cluster glass state were observed at low temperatures. It was thus concluded that the exchange interactions within Gd atoms in the clusters were not of the RKKY but of the superexchange type. The magnetocaloric effect (MCE) was investigated from the magnetic entropy change ( DSM) as a function of temperature, for the removal of a 50 kOe field. Samples with x < 0,2 exhibited DSMxT curves whose shapes are typical of a superferromagnet, consistently with the existence of Gd clusters in the films. For all the other alloys whose MCE was investigated, the presence of clusters is manifested from the behavior of these curves at low temperatures; at higher temperatures, the evolution of DSM with T strongly indicated the presence of more than one magnetic phase in the alloys A magnetic phase diagram based on the Tf and Tc transition temperatures and their dependence on x is presented in this thesis
Doutorado
Física da Matéria Condensada
Doutor em Ciências
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Zarpelon, Lia Maria Carlotti. « Estudo das características eletroquímicas e microestruturais de eletrodos de hidreto metálico à base de LaNi com adições de elementos de liga ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-19012017-092218/.
Texte intégralRésumé :
Neste trabalho avaliou-se a ação positiva da substituição de lantânio por praseodímio e de lantânio por magnésio na performance eletroquímica de eletrodos de ligas de armazenamento de hidrogênio em estado bruto de fusão e com tratamento térmico. O La foi substituído por Mg nas ligas La0,7-xMgxPr0,3Al0,3Mn0,4Co0,5Ni3,8 (x=0,0-0,7) e por Pr nas ligas La0,7-yPryMg0,3Al0,3Mn0,4Co0,5Ni3,8 (y=0,0-0,7). Os parâmetros eletroquímicos analisados foram ativação, capacidade de descarga, retenção da capacidade de descarga, autodescarga e alta taxa de descarga. As ligas apresentaram comportamento passivo em relação à corrosão. As análises por MEV/EDS e por DRX com refinamento por Rietveld revelaram a presença majoritária de fases similares às fases LaNi5, PrNi5, LaMg2Ni9 e PrMg2Ni9 em função das composições das ligas estudadas. Os parâmetros de rede e os volumes da célula unitária das fases diminuíram com a substituição crescente de La por Mg e de La por Pr. As capacidades de descarga máxima decresceram com a substituição crescente de La por Mg e de La por Pr, acompanhando o decréscimo da abundância da fase similar à fase LaNi5 e o aumento da abundância da fase similar à fase LaMg2Ni9. Comparativamente, menores taxas de autodescarga e maior estabilidade cíclica foram observadas para o eletrodo da liga na condição x=0,1, ao passo que o eletrodo da liga na condição y=0,0 apresentou maiores valores de alta taxa de descarga, indicando melhor performance cinética.In this work, the positive action of the substitution of lanthanum by praseodymium and lanthanum by magnesium in the electrochemical performance of the as-cast and annealed hydrogen storage alloys electrodes had been evaluated. La was replaced by Mg in La0.7-xMgxPr0.3Al0.3Mn0.4Co0.5Ni3.8 (x=0.0-0.7) alloys and by Pr in La0.7-yPryMg0.3Al0.3Mn0.4Co0.5Ni3.8 (y=0.0-0.7) alloys. The electrochemical parameters analyzed were activation, discharge capacity, discharge capacity retention, self-discharge rate and high-rate dischargeability. The alloys showed a passive corrosion behavior. The analyses by SEM/EDS and XRD with Rietveld refinement revealed the majority presence of LaNi5, PrNi5, LaMg2Ni9 and PrMg2Ni9 similar reference phases depending on the compositions of the studied alloys. The lattice parameters and cell volumes of the component phases decreased with increasing substitution of La for Mg and with La for Pr. The maximum discharge capacity decreased with increasing substitution of La for Mg and with La for Pr, following the decrease in the abundance of LaNi5 similar phase and the increase in the abundance of to the LaMg2Ni9 similar phase. Lower self-discharge rates were observed for the alloy electrode when x=0.1, while higher high-rate dischargeability for the alloy electrode when y=0.0 indicated better kinetic performance, comparatively.
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Medeiros, Pedro Samuel Gomes. « Desenvolvimento e caracteriza??o de solu??es tern?rias ?gua-glicerol-propilenoglicol como fluido refrigerante secund?rio ». Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15696.
Texte intégralRésumé :
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Previous issue date: 2012-12-17Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
Cada vez mais o mundo est? adotando uma matriz energ?tica limpa e sustent?vel, com o uso da agricultura para produ??o de agroenergia e combust?veis verdes, como bioetanol e biodiesel. A produ??o do biodiesel gera um coproduto, a glicerina, em que as usinas produtoras t?m dificuldades com o destino do seu excedente. V?rias pesquisas est?o sendo desenvolvidas para nortear diferentes usos do glicerol (glicerina pura). O glicerol possui total solubilidade com a ?gua e pode ser usado como aditivo anticongelante aplicado como fluido refrigerante secund?rio, em sistemas de refrigera??o indireta e com termoacumula??o. Tamb?m, o glicerol ? uma mat?ria-prima alternativa na produ??o de propilenoglicol, um ?lcool de grande aplicabilidade industrial inclusive como anticongelante. Por?m, o melhor ?lcool anticongelante ? o etilenoglicol, um ?lcool t?xico derivado do petr?leo. As solu??es ?gua-glicerol (AG) e ?gua-propilenoglicol (AP) possuem propriedades termof?sicas de qualidade inferior e desequilibradas se comparadas ?s solu??es ?gua-etilenoglicol (AE). Desta forma, esta pesquisa inovadora teve como prop?sito o desenvolvimento e a caracteriza??o de solu??es tern?rias ?gua-glicerol-propilenoglicol (AGP) como fluidos secund?rios, com propriedades termof?sicas desej?veis e competitivas com as solu??es ?gua-etilenoglicol. Equa??es preditivas simplificadas foram usadas para prever o comportamento das solu??es AGP, onde as seguintes propriedades termof?sicas foram avaliadas e estimadas teoricamente: ponto de congelamento, massa espec?fica, calor espec?fico e condutividade t?rmica. As concentra??es para definir o ponto de congelamento das solu??es AGP foram definidas a partir da Lei de Raoult das propriedades coligativas. A an?lise matem?tica inicial mostrou que as solu??es AGP possuem propriedades mais equilibradas que as solu??es AG e AP e competitiva com a solu??o AE. A comprova??o experimental das solu??es AGP foi feita a partir de ensaios para verificar suas propriedades (massa espec?fica, condutividade t?rmica e viscosidade din?mica), comparando com as solu??es de refer?ncia AG e AP. Os resultados experimentais comprovaram as expectativas iniciais e viabilidade t?cnica do novo fluido secund?rio tern?rio. A grande vantagem dos fluidos AGP ? que s?o at?xicos e derivam de fontes renov?veis
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Vermoote, Patricia. « Glucosamine-6-phosphate synthetase d'escherichia coli : purification, proprietes, localisation du site actif, et etude de son inhibition par des composes naturels et leurs derives ». Paris 6, 1988. http://www.theses.fr/1988PA066583.
Texte intégralRésumé :
Purification de la glucosamine-6-phosphate synthetase et mise au point d'un dosage enzymatique rapide et fiable. Determination des proprietes physico-chimiques, de la composition en acides amines et de la sequence amino-terminale de l'enzyme, ainsi que de son mecanisme cinetique
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Sun, Shao-Wen, et 孫紹文. « Liquid Crystalline Properties of Unsymmetrically Terminal Alkenyl imidazolium Salts ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/25707550237799756139.
Texte intégralRésumé :
碩士國立東華大學
化學系
97
Vinyl substituted imidazolium salts, with bromide, iodide, BF4, and PF6 anionic groups and higher homologous 1-alkenylimidazolium bromides were synthesized and characterized. Vinylimidazolium salts with alkyl chain lengths greater than 12 exhibit smectic A phase. In the crystal phase, the bromides show an interdigitated double bilayer structure while the other series show simple bilayer structures. The mesophase structure is similar for all the compounds. Some compounds also show an additional metastable crystal phase on cooling. The vinyl substituted bromides and iodides show stronger intermolecular interactions than the corresponding ethyl substituted salts, resulting in higher melting and clearing points and a wider mesophase range. The higher homologous 1-alkenyl imidazolium bromides show only a bilayer structure in the crystal phase. They show a smectic A phase up to 1-butenyl, and probably a smectic C phase in 1-heptenyl and 1-octenyl. Mixing mesogenic vinylimidazolium iodides with room temperature ionic liquids of vinylimidazolium iodide gave room temperature ionic liquid crystals.
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葉翠萍. « Synthesis and Properties of Terminal Biphenyl Ether Substituted Thermotropic Liquid Crystals ». Thesis, 1995. http://ndltd.ncl.edu.tw/handle/07437026713672165349.
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碩士國立成功大學
化學學系
83
A series of monomers containing biphenyl phenyl benzoate based mesogenic core with various lengths of oligo ( ethylene glycol) monomethyl ether as terminal group were synthesized. The structure and the thermodynamic properties of these compounds were investigated. The purpose of this work is to improve the thermal stability of these series of compounds. The purity, the thermotropic trasition temperature and the mesophase texture were studied by means of nuclear magnetic resonance spectroscopy, differential scanning calorimetry and optical polarized microscopy with a hot stage. All the monomers synthesized occur nematic mesophase. The decrease of melting point(Tm), isotropic transition temperature (Ti) and thermodynamic parameter with the increasing the lengths of alkenyloxy group were observed. Similar results were found for the decrease of melting point, isotropic transition temperature and thermodynamic parameter with the increasing lengths of the terminal group. With the increase of the number of phenyl rings of mesogenic group, the Tm and Ti values will also increase.
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Wang, Chung-Shu, et 王崇旭. « The Effect of Terminal Functional Group on Mesomorphic Properties of Benzoxazole Derivatives ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/21502841229740618182.
Texte intégralRésumé :
碩士國立中央大學
化學研究所
92
Abstract In this thesis, we report the synthesis, characterization and mesomorphic properties of two novel series of new mesogenic derivatives based on [4-(6-alkoxybenzoxazol-2-yl)phenyl]-4-X-benzy lidenes (as shown below, X = CN, F, Cl, NO2, OCH3 and etc.) and metal complexes of 5-alkoxy-2-{[4-(6-alkoxybenzoxazol-2-yl)phenylimino] methyl}phenols. These compounds were all characterized by 1H-NMR and 13C-NMR spectroscopy, and their mesomorphic properties were studied by differential scanning calorimeter (DSC) and polarized optical microscopy (POM). The results indicated that all compounds exhibited nematic (N) and/or smectic A phases (SmA) and/or smectic C phases (SmC), as expected by rod-like molecules. In addition, the mesomorphic properties observed by these compounds were found to be strongly dependent on the terminal group attached. The effect of mesomorphic properties, which was determined by the electronic and/or steric configuration of the terminal groups, will be also discussed. For example, smectic A phase was observed for the derivative with CN attached as terminal group, however, nematic phase was in fact observed for the derivative with OCH3 group. The effect of the carbon chain length of side chains on the mesomorphic properties will be also investigated. Copper(II), palladium(II), and nickel(II) complexes exhibited mesomorphic properties, however, cobalt(II) and zinc(II) complexes were not mesogenic.
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Lin, Yeh-Yung, et 林燁雍. « Identify the structural properties of TDP-43 C-terminal fragments associated with ALS ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26467456337245555321.
Texte intégralRésumé :
碩士國立臺灣科技大學
工程技術研究所
98
Many neurodegenerative diseases (NDDs), including Alzheimer’s disease (AD), Huntington’s disease (HD), Motor neuron disease (MND), Parkinson’s disease (PD), and Amyotrophic lateral sclerosis (ALS), have been realized to associate with inclusion body formation and protein aggregation of molecular and cellular mechanisms. These aggregates usually appear as fibril morphology and consist of β-sheet structure. ALS is the third common neuron degenerative cause of adult death, after AD and PD. It is also the most adult-onset motor neuron disease (MND), cause of progressive weakness, muscular wasting, and death within a few years. However, the exhaustive mechanism and the possible treatment for this disease remained unavailable. In 2006, TAR DNA-binding protein (TDP-43), containing 414 residues, was identified as the main sediments in the histopathological inclusion bodies of ALS and frontotemporal lobar degeneration (FTLD-U). Recent literatures have further indicated that the major component in the inclusions of ALS and FTLD patients were hyperphosphorylated TDP-43 C-terminal fragments. In order to understand the role of C-terminal domain of TDP-43 in ALS, we have synthesized four peptide fragments located in different regions of C-terminus to uncover the relationship between fibrial structure and aggregation state. Interestingly, only the D1 formed twisted fibrils after incubating in phosphate buffer for two weeks. D2, D3 and D4, on the other hand, were detected as amorphous aggregates by EM measurement. Moreover, two pathological mutant peptides, A315T and G294A, also had the ability to form fibrils that displayed the similar morphology with neuronal cytoplasmic inclusions (NCIs). In the meantime, we used the circular dichroism (CD) spectroscopy to trace the change of secondary structure. It revealed that only the G294A had significantly been altered. Moreover, we successfully identified the specific conformation of D1, A315T, and G294A peptide fragments by applying fluorescence and Raman spectroscopy. We found only G294A had strong emission with the addition of ThT. From the results of FT-Raman spectra, the aggregation of all three peptides belongs to amyloid structures. Base on these results, we proposed that the region (sequence: 287-322) contains many glycine repeats in C-terminus may play an important role in the fibril formation as well as aggregation formation.
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Howard, Rebecca Joy. « Structure and assembly properties of a conserved C-terminal domain in Kv7 channels ». Diss., 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3289330.
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Wu, Chun-Yi, et 吳純宜. « Roles of C-terminal Region of Serratia marcescens Recombinant Chitinase on Enzyme Properties ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33153978362169134904.
Texte intégralRésumé :
碩士國立臺灣海洋大學
生物科技研究所
99
Abstract A chitinase gene (SmChiC) and its C-terminal truncated mutants , SmChiCG426 and SmChiCG330 of Serratia marcescens were cloned by polymerase chain reaction (PCR) techniques. To study the role of the C-terminal domains of SmChiC on the enzyme properties, the recombinant SmChiC, SmChiCG426 and SmChiCG330 encoded in 1,440, 1,276 and 990 bp DNA fragments, respectively, were expressed in Escherichia coli using the pET-20b(+) expression system. The His-tag affinity purified SmChiC¸SmChiCG426 and SmChiCG330 enzymes had a calculated molecular mass of 51¸46 and 36 kDa, respectively. Results of biochemical characterizations including kinetic parameters, spectroscopy of fluorescence and circular dichroism, chitin binding ability and thermostability, indicated that they had very similar physicochemical properties such as the optimum pH (5), temperature (55°C), thermostability (50°C), the same hydrolyzing product, chitobiose, and similar protein secondary structures. Comparative studies revealed that the overall catalytic efficiency, kcat/Km ,was slightly increased for both truncated enzymes toward the soluble 4-methylumbelliferyl-N-N’-diacetyl chitobiose and the binding ability of insoluble α-chitin substrate was decreased. Fluorescence and circular dichroism (CD) spectroscopy suggested that both C-terminal deletion mutants retained an active folding conformation similar to the full-length enzyme. However, a CD melting study indicated that SmChiCG330 had no obvious transition temperature as SmChiC and SmChiCG426 did.
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Gao, Hua-de, et 高華德. « The Analysis of Biochemical Properties of Different N-terminal Fragments of Prion Protein ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/57001549814418087202.
Texte intégralRésumé :
碩士國立中正大學
分子生物研究所
100
Transmissible Spongiform Encephalopathies (TSEs) is known as the prion disease that is infected by PrPSc, a highly aggregated, β-sheet–rich isoform of the cellular prion protein (PrPC). The misfolding of PrPC induces amyloid aggregation that damages the brain tissue. Different from other neurodegenerative diseases, experimental studies have confirmed the transmissibility of prion disease in vitro and in vivo among species. PrP106-126 has been reported to be very toxic and aggregate in cell model. Furthermore, the N-terminus of prion protein is non-structured in NMR data, but there are some evidences that amyloid beta (Aβ) interact with N-terminal but not C-terminal prion. In this study, we built the constructs for expressing mouse PrPWT, PrP23-89, PrP23-140, PrP23-170 proteins and analyed their biochemical properties. All MoPrP23-89, MoPrP23-140, MoPrP23-170 are non-structured according to CD spectra. Interaction with copper ions decreases the CD signal. In fibril conversion, only the MoPrP23-170 can form amyloid fibril under 0.5 M GdnHCl condition. All of the N-terminal prion can increase MoPrPWT fibrillation, and the MoPrP23-170 has the same result for fibrillation as does of MoPrPWT with 2-fold concentration. The incorporation of N-terminal MoPrPs into MoPrPWT fibril is critical to understand the fibril procession.
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Yan, Bo-Shiun, et 顏伯勳. « Studying the properties of the C-terminal region of the hepatitis C virus core protein ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/4r4xvc.
Texte intégralRésumé :
博士國立陽明大學
微生物暨免疫學研究所
87
Hepatitis C virus (HCV) is a single, positive-stranded, enveloped virus with a 9.5-kb RNA genome. Its genome encodes a single polyprotein precursor of about 3000 residues that is matured into structural (C, E1 and E2) and nonstructural proteins (NS2-NS5). The N-terminal region of the core protein is rich in basic residues, while the C-terminal end has a stretch of hydrophobic amino acids. In between these two extremes is an amphipathic region with a leucine zipper-like structure that is possibly involved in self-association. To investigate this possibility, the core sequence was divided into two fragments and expressed separately as recombinant proteins. The recombinant N-terminal fragment remained as monomers even at high concentrations upon SDS-PAGE analysis. The C-terminal recombinant fragment appeared largely monomeric on denaturing gels but some oligomers were also detected. Furthermore, proline mutations in either one of the predicted a-helixes adversely affected the observed oligomerization. The self-association capacity of the core protein C-terminal region was further supported by results from a yeast two-hybrid system. To affirm our conclusion, a peptide covering the leucine-zipper region was synthesized. Data from mass spectrometry and gel filtration chromatography concluded that this peptide readily dimerized. Therefore, these results suggested that the C-terminal region of the core protein is capable of self-association. All HCV structural proteins have a hydrophobic peptide stretch at their C-terminal region. These peptides serve as signal sequences for the processing of their downstream proximal product. These molecular organizations may encode additional information to determine the destination of structural proteins. To address this possibility, the processing of a precursor containing C, E1, and the N-terminal end of E2 was synthesized in vitro . Lacking the entire core or the C-terminal hydrophobic segment of C, the processing of E1 was prohibited and the downstream signal peptide at the C-terminus of E1 lost its function. These results suggest that the signal peptide at the C-terminus of core has to be retained to warrant a successful processing of the E1-E2 junction and support a model that the E1-E2 junction would not be processed unless the C-E1 reaches the destination. Furthermore, to direct the precursor protein for processing, this core C-terminal signal sequence appeared to be replaceable by that at the E1 C-terminus covering residues 364-383. Subcellular localizations of the core products processed from different constructs were also examined on HuH-7 cells transfected with different expression plasmids. The cells were simultaneously stained with antibodies against core and calnexin, an ER protein. The immunofluorescence images were examined with a confocal laser scanning microscope. The results indicate that the core products were translocated to a compartment with an ER-like structure, as long as they were processed from a precursor that contains an appropriate signal sequence. This compartment is probably not the ER lumen where calnexin is located. A second stretch (residues 150-173) of the C-terminal sequence of the core protein has also been found to function as a signal sequence. This property may explain, at least in part, why the core protein has a strong capacity to associate with ER, where the core proteins may be further modified and/or translocated.
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Lin, Hsu-Yang, et 林旭陽. « Effects of C-terminal Truncation of Amylopullulanase from Thermoanaerobacter ethanolicus 39E on Recombinant Enzyme Properties ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/97344442803945311544.
Texte intégralRésumé :
博士國立臺灣海洋大學
生物科技研究所
97
The purpose of this thesis is to explore the functional and structural significance of the C-terminal region of Thermoanaerobacter ethanolicus 39E amylopullulanase (TetApu) using C-terminal truncation mutagenesis. Comparative studies between the engineered full-length (TetApuM955) and its truncated mutant (TetApuR855) included initial rate kinetics, fluorescence and CD spectrometric properties, substrate binding and hydrolysis abilities, thermostability, and thermodenaturation kinetics. Kinetic analyses revealed that the overall catalytic efficiency, kcat/Km, was slightly decreased for the truncated enzymes toward the soluble starch or pullulan substrate. Changes to the substrate affinity, Km, and turnover rate, kcat, varied in different directions for both types of substrates between TetApuM955 and TetApuR855. TetApuR855 exhibited a higher thermostability than TetApuM955, and retained similar substrate-binding ability and hydrolyzing efficiency against the raw starch substrate as TetApuM955 did. Fluorescence spectroscopy indicated that TetApuR855 retained an active folding conformation similar to TetApuM955. A CD-melting unfolding study was able to distinguish between TetApuM955 and TetApuR855 by the higher apparent transition temperature in TetApuR855. These results indicate that up to 100 amino acid residues, including most of the C-terminal fibronectin typeIII (FnIII) motif of TetApuM955, could be further removed without causing a seriously aberrant change in structure and a dramatic decrease in soluble starch and pullulan hydrolysis.
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Lu, Ya-Ling, et 呂雅鈴. « Synthesis and Photochemical Properties of Photochromic Compounds Containing Various Flexible Spacer Lengths and Terminal Groups ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/64621325015817538797.
Texte intégralRésumé :
碩士朝陽科技大學
應用化學系碩士班
98
In this work, three series of novel cholesterol-based photochromic compounds, named as Nazo, Cazo, and Nstil series, containing various photochromic moieties, flexible spacer lengths and terminal groups using esterization reaction were designed and synthesized. Their structure-property relation of liquid crystals and the effect on E/Z photoisomerization were also investigated. The chemical structures of the synthesized compounds were identified using FTIR, 1H-NMR, 13C-NMR, and EA analyzer. The thermal and optical properties of compounds were evaluated using DSC, POM, UV-Vis, and PL techniques. All mesophase of the synthesized compounds revealed enantiontropic cholesteroc liquid crystals with planar textures. The maxima absorption for Nazo, Cazo, and Nstil series are in the range of 342-381, 349-359, and 354-378 nm, respectively. Nstil series showed the maxima quantum efficiencies in the range of 0.37~0.66. The increase of LC cell temperature and UV irradiation induced blue-shifts of the selective light reflection of cholesteric phases. Synthesized photochromic compounds containing N=N and C=C segments revealed one reversible and one irreversible photochromic properties.Photochromic compounds with various photoisomerizable groups fabricated in this investigation could be used as irreversible image recording and rewritable data storage systems. The results of this investigation present significant scientific and practical contributions with respect to the development of unique functional photochromic materials.