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Статті в журналах з теми "Denses materials":
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Rymaszewski, E. J. "Dense, denser, densest ..." Journal of Electronic Materials 18, no. 2 (March 1989): 217–20. http://dx.doi.org/10.1007/bf02657412.
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Younes, Rassim, Mohand Amokrane Bradai, Abdelhamid Sadeddine, Youcef Mouadji, and Abderrahim Benabbas. "Influence des post-traitements sur la résistance à l’usure des dépôts en superalliage Ni-Cr-Al-Mo obtenus par projection thermique." Matériaux & Techniques 106, no. 6 (2018): 605. http://dx.doi.org/10.1051/mattech/2019003.
Анотація:
Ce travail porte sur la caractérisation microstructurale, structurale et mécanique des dépôts métalliques à base Nickel déposés sous forme de poudres par la technique de projection thermique flamme-poudre sur un substrat type E335. Pour améliorer les propriétés de ces dépôts, des traitements thermiques sont préconisés en vue d’homogénéiser ces derniers et permettre d’obtenir de meilleures propriétés mécaniques. Ces post-traitements ont été réalisés à différentes températures 400, 600 et 800 °C avec un temps de maintien d’une heure et un refroidissement à l’air. La caractérisation structurale et microstructurale de la poudre et des dépôts est obtenue en utilisant le microscope électronique à balayage (MEB) et la diffraction X (DRX). Des relevés de micro duretés Vickers ont été également réalisés sur la surface de ces dépôts. Les essais tribologiques ont été réalisés avec une configuration pion-disque à différentes charges avec deux vitesses de glissement en vue de déterminer le taux d’usure. Les observations microstructurales ont montré que les traitements effectués aux températures de 400 et 600 °C ont réduit les porosités en rendant les microstructures plus homogènes et plus denses par le phénomène de colmatage. Par contre, le traitement à 800 °C a présenté un délaminage au niveau de l’interface substrat/dépôt. Les résultats d’usure ont révélé que la vitesse de glissement et la pression de contact appliquée influent sur la variation du taux d’usure et que les dépôts traités à 400 °C présentent une meilleure résistance à l’usure que ceux traités à 600 et 800 °C.
3
Puckett, James G., Frédéric Lechenault, Karen E. Daniels, and Jean-Luc Thiffeault. "Trajectory entanglement in dense granular materials." Journal of Statistical Mechanics: Theory and Experiment 2012, no. 06 (June 19, 2012): P06008. http://dx.doi.org/10.1088/1742-5468/2012/06/p06008.
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ROGNON, PIERRE G., JEAN-NOËL ROUX, MOHAMED NAAÏM, and FRANÇOIS CHEVOIR. "Dense flows of cohesive granular materials." Journal of Fluid Mechanics 596 (January 17, 2008): 21–47. http://dx.doi.org/10.1017/s0022112007009329.
Анотація:
Using molecular dynamic simulations, we investigate the characteristics of dense flows of model cohesive grains. We describe their rheological behaviour and its origin at the scale of the grains and of their organization. Homogeneous plane shear flows give access to the constitutive law of cohesive grains which can be expressed by a simple friction law similar to the case of cohesionless grains, but intergranular cohesive forces strongly enhance the resistance to the shear. Then we show the consequence on flows down a slope: a plugged region develops at the free surface where the cohesion intensity is the strongest. Moreover, we measure various indicators of the microstructure within flows which evidence the aggregation of grains owing to cohesion and we analyse the properties of the contact network (force distributions and anisotropy). This provides new insights into the interplay between the local contact law, the microstructure and the macroscopic behavior of cohesive grains. Movies are available with the online version of the paper.
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Honaker, R. Q., and C. Bimpong. "Alternative Materials for Dense Medium Separations." International Journal of Coal Preparation and Utilization 29, no. 4 (July 29, 2009): 173–91. http://dx.doi.org/10.1080/19392690903102329.
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Liu, Chuanqi, Qicheng Sun, and Guohua Zhang. "Multiscale properties of dense granular materials." Engineering Computations 32, no. 4 (June 15, 2015): 956–72. http://dx.doi.org/10.1108/ec-04-2014-0084.
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Yang, Wen, Nai Qian Feng, Ch’ng Guan Bee, and Xiao Qin Liu. "Research on the Effect of Beads on Properties and Microstructure of Cementing Materials." Applied Mechanics and Materials 357-360 (August 2013): 1229–34. http://dx.doi.org/10.4028/www.scientific.net/amm.357-360.1229.
Анотація:
The paper studied the effects of different contents of beads on powder pressure entity dense packing density, mechanical performance of composite cement paste. The microstructure of the composite paste is researched by SEM analysis and nitrogen adsorption method. The results show that when the beads content is low, the compacting voidage decreases with the increased bead contents. When the beads content is 30%, composite cementing material achieves the densest packing density. The compacting voidage of composite cement powder has strong correlation with the pore structure and strength of hardened cement paste. When the compacting voidage value reaches minimum, the average pore radius and maximum pore radius of hardened cement paste reach the minimum values. In addition, the 28d strength of composite cement paste is higher than ordinary cement paste.
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Mohaddes Pour, Mehrdad, and Seyed Sina Razavi Taheri. "Experimental Study of the Aggregate Shapes in Self-Compaction." Shock and Vibration 2021 (July 20, 2021): 1–18. http://dx.doi.org/10.1155/2021/7612956.
Анотація:
Compaction operations have a vital role in embankments or rock fills to avoid settlement, but in some projects, such as marine ones, it is hardly possible to accomplish compaction operations due to the problems and executive limitations. In situations with no possibility of compaction, it is recommended to use single-size or self-compacted materials. From a theoretical point of view, self-compacted materials consist of coarse aggregates with no vast domain of gradation. In this case, the porosity of the materials in the dense state is not significantly different from the loose one, and a relatively dense condition occurs after it is poured; thus, the mass of materials will undergo lower volumetric changes in the future. In this study, the self-compacted characteristic of materials has been investigated using real aggregates with different gradations (the ratio of the largest to the smallest aggregate size of 1, 2, 4, and 8). The gradation and shape of aggregates are the main variables examined in the research. Real aggregates have been used in order to compare the study of self-compacted idea with ideal aggregates and the effects of sphericity and angularity of them. According to the experiments carried out on samples in the present work, it was observed that, without compaction operations, even ideal materials would not be in fully self-compacted state. However, relatively denser conditions can be achieved by observing the necessary points. Moreover, aggregates with high sphericity have better self-compacted property. Furthermore, the more uniform gradation and bigger size of materials lead to more self-compacted pile of materials.
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Gibson, Lorna J. "The hierarchical structure and mechanics of plant materials." Journal of The Royal Society Interface 9, no. 76 (August 8, 2012): 2749–66. http://dx.doi.org/10.1098/rsif.2012.0341.
Анотація:
The cell walls in plants are made up of just four basic building blocks: cellulose (the main structural fibre of the plant kingdom) hemicellulose, lignin and pectin. Although the microstructure of plant cell walls varies in different types of plants, broadly speaking, cellulose fibres reinforce a matrix of hemicellulose and either pectin or lignin. The cellular structure of plants varies too, from the largely honeycomb-like cells of wood to the closed-cell, liquid-filled foam-like parenchyma cells of apples and potatoes and to composites of these two cellular structures, as in arborescent palm stems. The arrangement of the four basic building blocks in plant cell walls and the variations in cellular structure give rise to a remarkably wide range of mechanical properties: Young's modulus varies from 0.3 MPa in parenchyma to 30 GPa in the densest palm, while the compressive strength varies from 0.3 MPa in parenchyma to over 300 MPa in dense palm. The moduli and compressive strength of plant materials span this entire range. This study reviews the composition and microstructure of the cell wall as well as the cellular structure in three plant materials (wood, parenchyma and arborescent palm stems) to explain the wide range in mechanical properties in plants as well as their remarkable mechanical efficiency.
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Sobczak, Agnieszka, Anna Kida, Zygmunt Kowalski, and Zbigniew Wzorek. "In vitro tests of dense hydroxyapatite materials." Polish Journal of Chemical Technology 11, no. 1 (January 1, 2009): 44–49. http://dx.doi.org/10.2478/v10026-009-0011-4.
Анотація:
In vitro tests of dense hydroxyapatite materials The paper presents the results of the calcining process of deproteinised and defatted bone pulp called bone sludge. The calcining process was performed in two stages. The first step of the calcining process was realized at the temperature of 600°C in a rotary kiln. In the second stage the obtained bone ashes were calcined at five different temperatures from 650°C to 950°C for 2 hours in a chamber kiln and in air atmosphere. The products of the calcining process were characterized by the XRD method. Calcium content was determined by titration whereas the contents of total phosphorus and acid-soluble phosphorus - by the spectrophotometric method. The X-ray analysis confirmed that hydroxyapatite is the main component of the calcining products. Calcium and phosphorus contents were kept at the level of 40% and 17.5%, respectively, which corresponded to the Ca/P ratio of not stechiometric hydroxyapatite. In vitro studies, in the simulated body fluid, Ringer liquid and distilled water were realised. The measurements of pH value of SBF and Ringer fluid were realized. Additionally electrical conductivity as well as pH for distilled water where conducted. The goal of these tests was to evaluate chemical durability of dense hydroxyapatite materials.
Дисертації з теми "Denses materials":
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Maillard, Mathilde. "Imprimabilité de pâtes céramiques par robocasting : Applications aux matériaux denses et multimatériaux." Thesis, Lyon, 2022. https://theses.insa-lyon.fr/publication/2022LYSEI035/these.pdf.
Анотація:
Ce travail de thèse a pour objectif d'élaborer des pièces céramiques denses mono et multi-matériaux ayant des architectures complexes. Ces architectures sont réalisées à l'aide d'une technologie de fabrication additive d'extrusion de pâtes céramiques à travers une fine seringue (DIW : robocasting). Ce travail de recherche est financé par le projet ANR CERAPIDE qui a pour objectif la réalisation de pièces céramiques plus rapidement et en consommant moins d'énergie, de sa formulation jusqu'aux étapes de post traitements thermiques. Ainsi, les formulations des pâtes sont optimisées en adaptant les additifs et leurs quantités dans le but d'obtenir des pâtes homogènes, sans défauts et ayant les propriétés rhéologiques nécessaires pour l'impression. Une pâte céramique doit entre autres disposer d'un comportement rhéofluidifiant tout en disposant d'une contrainte seuil élevée pour pouvoir être imprimée par empilement successif de couches. La maitrise rhéologique et l'optimisation des formulations permettent d'imprimer des pièces denses avec des propriétés mécaniques améliorées. Le changement d'additif permet de modifier l'état de surface des pièces denses et donc de modifier les propriétés mécaniques des pièces. La définition de l'imprimabilité des pâtes céramiques est étudiée pour comprendre les relations entre les propriétés microstructurales, environnementales et technologiques. Ainsi, les paramètres d'impressions doivent être sélectionnés en fonction des propriétés finales souhaitées pour la pièce imprimée. La compréhension de tous ces paramètres permet d'élaborer des pièces en alumine ayant une moyenne de contrainte à la rupture de 350 MPa sans étapes de polissageThe main goal of this thesis is to elaborate dense single and multi-material ceramic parts with complex architectures. These architectures are realized using an additive manufacturing technology of extrusion of ceramic pastes through a fine syringe (DIW : robocasting). This research work is financed by the ANR CERAPIDE project, which aims to produce ceramic parts more quickly and with less energy consumption, from formulation to post heat treatment stages. Thus, the formulations of the pastes are optimized by adapting the additives and their quantities in order to obtain homogeneous pastes, without defects and having the rheological properties necessary for printing. Among other things, a ceramic paste must have be shear-thinning while having a high yield stress to be able to be printed by successive stacking of layers. The rheological control and the optimization of the formulations allow to print dense parts with improved mechanical properties. The change of additive allows to modify the topography of the dense parts and thus to modify the mechanical properties of the parts. The definition of printability of ceramic pastes is studied to understand the relationships between microstructural, environmental and technological properties. Finally, the printing parameters must be selected according to the final properties desired for the printed part. The understanding of all these parameters allows the development of alumina parts with an average stress at break of 350 MPa without polishing steps
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Simon, Jean-Christophe. "Diffusion électromagnétique dépendante dans les milieux hétérogènes denses." Rouen, 1994. http://www.theses.fr/1994ROUES061.
Анотація:
Il est montré que la diffusion électromagnétique dans les milieux hétérogènes denses fait intervenir de nombreux couplages multipolaires entre les particules. Dans ce travail, la distinction est faite entre la diffusion indépendante, couramment utilisée, et la diffusion dépendante. La première partie décrit les effets de diffusions multiple et cohérente, phénomènes liés à la diffusion indépendante. L'équation de transfert radiatif est résolue par une méthode de Monte-Carlo, et l'influence des propriétés d'absorption du milieu environnant les particules est mise en évidence. Les limites de la diffusion indépendante sont exposées à l'aide d'une expérience d'extinction par des particules de verre placées dans une cuve. La seconde partie traite de la diffusion dépendante, et décrit sa théorie. Le théorème d'addition des fonctions d'onde vectorielles harmoniques sphériques est étudié numériquement, en montrant de nombreux exemples caractéristiques. Un critère de convergence des sommations infinies intervenant dans ce théorème est testé, et nous statuons sur ses limites. Enfin, l'application de cette théorie aux milieux réels fortement concentrés est discutée, et son adaptation à l'équation de transfert radiatif est étudiée
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Khamseh, Saeed. "Rheophysics of granular materials with interstitial fluid : a numerical simulation study." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1025/document.
Анотація:
Nous étudions la rhéologie d'un ensemble de grains sphériques et frottants, par la simulation numérique, à l'échelle des grains, d'écoulements de cisaillement sous une contrainte normale P contrôlée, en présence d'un liquide interstitiel. En faible teneur, ce liquide se présente sous forme de ménisques intergranulaires qui transmettent des forces capillaires attractives ; s'il sature l'espace intergranulaire, on s'intéresse alors à l'écoulement de Stokes de la suspension dense ainsi constituée, où dominent les forces visqueuses. Les assemblages de grains secs constituent un système de référence aux propriétés mécaniques bien connues, en particulier l'approche de l'état critique de la mécanique des sols dans la limite quasi-statique. L'effet des ménisques capillaires qui joignent les grains en présence d'un liquide en faible saturation (régime pendulaire) est étudié pour les taux de cisaillement allant du régime quasi statique au régime inertiel. La rhéologie est caractérisée par le frottement interne apparent, la compacité de l'assemblage, les différences de contraintes normales et diverses variables internes, fonctions de deux paramètres de contrôle adimensionnés : le nombre inertiel I et la pression réduite P*, qui compare les forces de confinement à l'adhésion dans les contacts. Notre étude concerne les états homogènes, ce qui exclut les états de cisaillement localisés observés à faible P*, de l'ordre de 0,1. Le coefficient de frottement interne augmente de 0.35 (cas sec) à 0.9 environ pour P*=0.4, tandis que la compacité décroît de 0.59 à 0.52. L'important effet des forces capillaires sur la rhéologie, sensible pour des P* de plusieurs unités, est relié à la texture anisotrope des contacts et des ponts liquides. Lorsque P* décroît, nombre de contacts cohésifs sont maintenus pour des intervalles de déformation de plusieurs unités, survivant aux effets de rotation et de cisaillement de l'écoulement, et forment des amas percolants dans le système entier. Les résultats sont modérément sensibles à la saturation dans le régime pendulaire, mais fortement affectés par l'hystérèse de la conformation des ménisques. En présence de forces visqueuses et non plus capillaires, une version simplifiée de la dynamique stokésienne est adoptée dans laquelle les forces de lubrification entre proches voisins, supposées dominantes, sont les seules interactions hydrodynamiques. La rhéologie est fortement influencée par les contacts intergranulaires directes, qu'autorise la coupure à courte distance de la singulérité de lubrification du fait de la rugosité de surface des particules. Le même état critique que celui des grains secs est approché dans la limite quasi-statique. Nous discutons de lois rhéologiques exprimées en fonction du nombre visqueux qui remplace alors le nombre inertiel, et de la divergence de la viscosité effective à l'approche de la compacité critique en écoulement permanent, ou de la compacité maximale des assemblages aléatoires pour les configurations isotropes désordonnéesWe numerically simulate the shear flow of dense assemblies of 3D frictional spherical grains under a fixed normal stress P in steady-state, either in the presence of a small amount of an interstitial liquid, which gives rise to capillary menisci and attractive forces, or in the fully saturated state, when the mechanical properties of suspensions in Stokes flow are controlled by hydrodynamic and contact forces. Dry grain assemblies are used as a reference system for which the rheological properties - in particular the approach to the critical state – are rather well known and can be measured with good accuracy. A non-saturating wetting fluid creates capillary attractive intergranular forces, the effects of which on the rheology are investigated in the pendular state, with shear rates ranging from quasistatic to inertial regimes. The system behavior is characterized by the dependence of internal friction coefficient, solid fraction, normal stress differences and internal state parameters on two dimensionless control parameters: the inertial number, I and the reduced pressure, P*, comparing confining forces to contact tensile strength. We focus on steady homogeneous flows, excluding localized flow patterns which we observe to occur for low P* (of order 0.1). The apparent internal friction coefficient increases to 0.9 in the quasistatic limit for P*=0.4, from its dry value 0.35, while solid fraction decreases from 0.59 to 0.52. We relate the significant effect of capillary forces on the macroscopic behavior of the system, up to P* values of several unities, to fabric anisotropy parameters of contact and distant interactions. As P* decreases, many cohesive contacts are observed to survive the tumbling motion associated to the shear flow, and their average age exceeds the reciprocal shear rate. Corresponding clusters of grains with enduring capillary bonds gather a large proportion of grains and percolate through the sample. The results are shown to be moderately sensitive to saturation within the pendular range, yet rather strongly affected by the hysteretic nature of liquid bridges. In the presence of viscous forces, assuming lubrication effects to dominate the hydrodynamic interactions, we adopt a simplified version of the (overdamped) Stokesian dynamics approach, in which hydrodynamic interactions only couple close neighbours. Rheological properties are strongly influenced by direct intergranular contacts and friction, which are permitted due to a very small distance lubrication cutoff modeling surface asperities. The same critical state as in the dry case is approached in the quasistatic limit. We discuss expressions of rheological laws involving the viscous number instead of the inertial number, and the divergence of effective viscosities in steady flow and in isotropic random suspensions as either the critical state or the random close packing solid fraction are approached
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Odinot, Julie. "Développement de la fabrication additive directe par DED-CLAD : de la poudre à la mise en forme de pièces céramiques denses." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN059.
Анотація:
Les techniques d’élaboration de matériaux par fabrication additive (FA) sont en plein essor [1]. Elles permettent de fabriquer des pièces par ajout de matière, en opposition avec les techniques traditionnelles par soustraction de matière (usinage). Il existe à l’heure actuelle de nombreux procédés de FA, adaptés à différentes applications : fusion ou frittage par faisceau d’électrons ou par laser, dépôt de matière direct ou en lit de poudre… Ces procédés ont été bien développés pour des matériaux polymères puis métalliques. Des techniques de FA de matériaux céramiques via des polymères chargés ont également vu le jour, mais celles-ci nécessitent des traitements postérieurs (cycles de déliantage, frittage) [2]. Les matériaux céramiques denses sont encore peu développés en fabrication additive en raison de la fissuration de ces matériaux lors de leur élaboration.La technologie CLAD (Construction Laser Additive Directe), développée par IREPA-LASER, permet la fabrication de pièces par dépôt de matière fondue. Le matériau sous forme de poudre est acheminé via une buse laser et projeté dans le faisceau. Il est ainsi porté à la température de fusion. La fusion successive de plusieurs couches permet l’obtention de la pièce. Cette technique, en plus de n’utiliser que la matière nécessaire (contrairement aux techniques de fabrication par lit de poudre), permet la fabrication de pièces de grandes dimensions, voire en multi-matériaux. Cette technologie est, pour l’heure, dédiée aux matériaux métalliques.L’objet de ce sujet de thèse, en partenariat entre l’ONERA et IREPA-LASER dans le cadre du projet inter-Carnot CLADIATOR, est d’étudier la FA de matériaux céramiques denses par le procédé CLAD®. Cette étude porte ainsi sur le procédé dans son ensemble, des matières premières aux pièces finales, en passant par l’adaptation du moyen de fabrication aux contraintes spécifiques liées aux matériaux céramiques.Les matières premières exigent d’être adaptées au procédé ; les deux principales difficultés étant la coulabilité de la poudre, nécessaire pour son acheminement dans la buse, et l’absorption de la source laser par le matériau pour sa montée en température. En parallèle de la caractérisation des matières premières (granulométrie, MEB, dilatométrie, DRX…), des essais d’atomisation par séchage seront effectués pour optimiser la coulabilité des poudres [3]. Ce procédé d’atomisation permet d’obtenir des poudres sous forme d’agglomérats sphériques de plus petites particules ; leur forme est régulière, mais elles restent poreuses. L’ajout de dopants sera étudié pour améliorer l’absorption du signal, en adéquation avec une éventuelle adaptation du laser. Les matériaux considérés sont l’alumine, la zircone ainsi que des compositions eutectiques d’alumine-zircone.La principale difficulté de ce sujet réside dans la sensibilité à la fissuration des matériaux céramiques, en raison du fort gradient thermique induit par le chauffage local du laser et le refroidissement de la pièce. Des solutions de chauffage de la pièce et/ou du matériau avant et après le dépôt seront étudiées pour limiter les contraintes thermomécaniques subies par le matériau [3,4].La machine devra également être modifiée pour supporter les températures élevées nécessaires à l’élaboration de céramiques (températures de fusion et dispositif de pré/post chauffage). L’étude et l’optimisation de ces solutions seront effectuées à l’aide de modélisations multi physiques sur le logiciel COMSOL en collaboration avec IREPA-LASER.Enfin, l’influence du procédé d’élaboration sur l’état des pièces réalisées sera étudiée grâce à des caractérisations microscopiques, mécaniques, thermiques…This work, in partnership between the ONERA Materials and Composite Structure Department (DMSC) and IREPA Laser within the CLADIATOR project, is based on the study of direct additive manufacturing of dense ceramic materials by direct melt deposition (also known as laser cladding) process. This process enables high dimensions or even multi-materials part manufacturing.It will deal with the adaptation of raw materials (ceramic powders) to the existing machine, especially in the case of powder flowability and optical absorption. Indeed, the powder flowability enables its transportation up to the laser nozzle, while the optical absorption of the laser signal is necessary to allow its melting.In parallel, the existing machine also needs to be adapted to ceramic materials : the main difficulty of this work will be the occurence of cracks during the manufacturing. This phenomena is due to the local heating by the laser and the materials brittleness. That’s why some secondary heating solutions, before or after the melt, will have to be defined to decrease the thermal gradient in the material while processing. Those solutions will be discussed between Onera and Irepa Laser, based on FEM simulations established with COMSOL Multiphysics software.Finally, the elaboration process influence on the manufactured ceramics parts will be investigated with microscopy, mechanical and thermal characterization
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Gonçalves, Luciano de Souza. "Resistencia da união a microtração de sistemas adesivos em função da remoção de colageno em dentes bovinos." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290105.
Анотація:
Orientador: Simonides ConsaniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo deste estudo foi avaliar dois sistemas adesivos (Prime & Bond 2.1 - PB2.1 e Prime & Bond NT - PBNT) aplicados sobre a dentina de dentes bovinos com prévia aplicação de solução de hipoclorito de sódio (NaOCl) a 10% por um minuto, por meio do teste de resistência de união a microtração em corpos-de-prova submetidos ou não à ciclagem mecânica e degradação hídrica. Quarenta incisivos centrais bovinos tiveram as coroas seccionadas e aleatoriamente separados em oito grupos. O desgaste da área a ser unida foi feito com lixas de granulação 600 e as amostras incluídas em cilindros de PVC. Nos grupos submetidos à ciclagem mecânica, a simulação do ligamento periodontal foi feita com elastômero à base de poliéter. As coroas foram confeccionadas com o compósito TPH Spectrum em incrementos de aproximadamente 2mm de espessura, com fotoativação de 20s por incremento, até completar 5,0mm de altura, sendo os grupos sem ciclagem mecânica: G1 - sistema adesivo PB2.1, G2 - sistema adesivo PBNT, G3 - sistema adesivo PB2.1 após tratamento com hipoclorito de sódio 10% por 60s e lavagem com água por 30s, e G4 - sistema adesivo PBNT após tratamento com hipoclorito de sódio 10% por 60s e lavagem com água por 30s. O mesmo tratamento foi realizado nos dentes dos grupos G5, G6, G7 e G8, submetidos a 50.000 ciclos mecânicos, após armazenagem por 24 horas. As amostras foram armazenadas por 24 horas em ambiente a 37ºC com umidade relativa de 100% e depois seccionados para a obtenção dos palitos, com secção lateral de 0,8mm. O ensaio foi realizado numa máquina universal. Metade dos palitos de cada amostra foi armazenada por 60 dias em água destilada a 37ºC, para observação dos efeitos da degradação hídrica. Os padrões de fratura foram observados em Microscópio Eletrônico de Varredura (110x). Os resultados obtidos (MPa) foram: G1a - 29,69 (6,63), G2a - 47,82 (4,70); G3a - 50,66 (9,14); G4a - 52,42 (11,82); G5a - 31,79 (10,73); G6a - 32,74 (9,62); G7a - 42,56 (7,52) e G8a - 43,34 (16,75) para os grupos ensaiados após 24 horas. Para os grupos após 60 dias, os resultados foram: G1b - 11,49 (4,22); G2b - 31,49 (5,76); G3b - 46,50 (13,66); G4b - 48,78 (7,73); G5b - 15,05 (6,85); G6b - 17,05 (7,18); G7b - 43,36 (7,26) e G8b 48,83 (12,22). Os valores foram submetidos à análise estatistica. O tratamento com hipoclorito de sódio mostrou valores estatisticamente semelhantes para o teste de resistência de união à microtração com ambos adesivos, quando os tempos 24 horas e 60 dias foram comparados, nos grupos ciclados ou não. Os grupos não tratados com NaOCl apresentaram valores estatisticamente inferiores após o armazenamento por 60 dias, quando comparado com os grupos após 24 horas. Dentro das limitações do estudo foi possível concluir que o tratamento com NaOCl aumentou os valores de resistência da união dos adesivos PB2.1 e PBNT testados 24 horas após a confecção das restaurações. Os grupos desproteinizados apresentaram-se menos suceptiveis a degradação hídrica quando comparados aos grupos restaurados com a técnica adesiva convencional
Abstract: The aim of this study was to evaluate the microtensile bond strength of two adhesive systems (Prime & Bond 2.1 - PB2.1 and Prime & Bond NT - PBNT) applied to bovine dentin previously treated with 10% sodium hypochlorite (NaOCl) solution. Specimens were submitted or not to mechanical cycling and hydrolytic degradation. Crowns of forty central incisors were seccioned and were randomly assigned to eight groups. Surface flattening of the area to be bonded was performed with 600-grit silicon carbide paper, and teeth were then embedded in PVC cylinders. For mechanical cycling groups, simulation of periodontal ligament was carried out with polyether-based elastomeric impression material. A 5-mm layer of resin was build up on the flattened surface using TPH Spectrum composite, adding 2-mm increments at a time, photocured for 20s. Groups not submitted to mechanical cycling: G1 - PB2.1; G2 - PBNT; G3 - PB2.1 after treatment with 10% NaOCl for 60s and rinsing with water for 30s; and G4 - PBNT after treatment with 10% NaOCl for 60s and rinsing with water for 30s. The same was conducted in groups G5, G6, G7 and G8, which were submitted to 50,000 mechanical cycles 24h after restorative procedures. After cycling, the specimens were stored at 37º C for 24h, and 100% relative humidity, and then sectioned to obtain 0.8mm-thick beams. Instron machine was used to test microtensile bond strength, at a crosshead speed of 0.5mm/min. Half of the beams were stored at 37º C for 60 days in distilled water, which was changed every week, to observe hydrolytic degradation effects. Fracture patterns were observed under scanning electron microscopy (110x). Results for the bond strength (MPa) at 24h were G1a -29.69 (6.63), G2a - 7.82 (4.70); G3a - 50.66 (9.14); G4a - 52.42 (11.82); G5a - 31.79 (10.73); G6a - 32.74 (9.62); G7a -42.56 (7.52) e G8a - 43.34 (16.75). For the groups tested after 60 days, the results were G1b - 11.49 (4.22); G2b -31.49 (5.76); G3b - 46.50 (13.66); G4b - 48.78 (7.73); G5b - 15.05 (6.85); G6b - 17.05 (7.18); G7b - 43.36 (7.26) e G8b 48.83 (12.22). Data were submitted to statistics analisys . For both adhesives, specimens treated with NaOCl showed no statistically difference bond strength values for the 24-h test period when compared to the 60-day period, considering groups submitted or not to mechanical cyclying. Untreated groups showed statistically lower values after 60 days compared to 24h. Within the limitations of this study, it was concluded that the treatment with NaOCl increased the bond strength values of Prime & Bond 2.1 and Prime & Bond NT tested 24h after preparation of the specimens. The groups submitted to deproteinization were found to be less susceptible to hydrolytic degradation when compared to groups restored using the conventional adhesive technique
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários
6
Carvalho, Cláudio Antonio Talge. "Avaliação in vitro da resistência estrutural em dentes fragilizados utilizando reforços intra-radiculares /." São José dos Campos, 2002. http://hdl.handle.net/11449/114073.
Анотація:
Orientador: Marcia Carneiro ValeraBanca: Silvia Lustosa de Castro
Banca: Maria Antonia Pereira
Banca: Alberto Siqueira e Silva
Banca: Ana Paula Martins Gomes
Resumo: Dentes com rizogênese incompleta quando sofrem trauma com conseqüente necrose pulpar permanecem com suas paredes dentinárias finas e fragilizadas, tornando-se mais suscetiveis a reincidências de fraturas. A proposta deste trabalho foi avaliar através do teste de compressão a resistência à fratura de dentes bovinos fragilizados que receberam reforços intra-radiculares com resina composta ou pino de fibra de zircônia. Para tanto, utilizou-se 56 dentes bovinos, os quais tiveram suas coroas seccionadas padronizando o tamanho das raízes em 30mm. Os dentes foram divididos em quatro grupos experimentais (14 dentes} e, com exceção do grupo 04 (Controle negativo), todos os canais radiculares foram preparados biomecanicamente até o instrumento de nº 80 e alargados com brocas Gates-Glidden nos 3, 4, 5 e 6 até 20mm de profundidade. A porção coronária foi alargada com broca diamantada tronco cônica nº 721 até a junção cemento-esmalte vestibular e, com broca diamantada tronco cônica nº 716, realizou-se a fragilização das paredes dentinárias do canal radicular a 20mm de profundidade, deixando aproximadamente 2mm de espessura em cada parede. Após, as raízes foram divididas em grupos: grupo 01-receberam reforço intra-radicular com resina composta, fotopolimerizada com o auxílio do sistema Luminex , seguida da obturação do canal; grupo 02-obturação do canal deixando os 10mm apicais com material obturador, e reforço intra-radicular com pino de fibra de zircõnia cimentado com cimento resinoso; o grupo 03-(Controle positivo) não recebeu reforço intra-radicular e foi obturado pela técnica da condensação lateral ativa; no grupo 04-(Controle negativo), os dentes não foram fragilizados. Os espécimes foram embutidos em blocos metálicos, os quais foram adaptados a um dispositivo cilíndrico, de modo que os espécimes foram fixados a 45°. Este dispositivo foi adaptado a um...
Abstract: lmmature teeth when suffer trauma with consequent necrosis pulpar they stay with its dentinal walls thin and brittle, becoming more susceptible to the second injuries. The purpose of this work is to evaluate through the compression test, the resistance to fracture of teeth bovine brittleness that received reinforcements within the root canal with composite resin or pins of zircônia fiber. lt was used 56 bovine teeth, which had its crowns sectioned in the medium third standardizing the size of the specimens in 30mm of length. The teeth were divided in four experimental groups (14 teeth) and, except for the group 04 (negative control), all the root canal was instrumented to #80 and enlarged firstly with drills Gates-Glidden numbers 3, 4, 5 and 6 to 20mm of depth, after, lhe coronary portion was enlarged with the conical drill number 721 until the cementoenamel junction facial and, with lhe conical drill number 716, the brittleness of the dentinal walls of the root canal at 20mm of depth, leaving 2mm of thickness approximately in each wall. After, the specimens of the group 01 received reinforcement within the root canal with composite resin, that was cured by aid of the Luminex system and, after, they were obturated; in lhe group 02, the specimens were obturated. Just leaving the 10mm apical with material, and they received reinforcement within the root canal with zircônia fiber pins cemented with resinous cement; the group 03 (positive control) it didn't received reinforcement within the root canal and it was obturated by the technique of the active lateral condensation; in the group 04 (negative control), the teeth were not brittleness. After, all the specimens were embedded with acrylic resin chemically activated, in metallic blocks, which were adapted to a cylindrical device, so that the specimens were fractured by load in angle of 45°. This device was adapted to a lnstron machine, ...
Doutor
7
Galetti, Roberta 1985. "Análise da resistência da união de sistemas adesivos à dentina de dentes submetidos à radioterapia in vivo." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288156.
Анотація:
Orientador: Mario Fernando de GoesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este estudo avaliou a resistência da união à dentina de dentes de pacientes que foram submetidos à radioterapia. Foram utilizados dezoito incisivos humanos extraídos de pacientes saudáveis (grupo controle) e dezoito incisivos de pacientes submetidos à radioterapia. As superfícies vestibulares de cada dente foram desgastadas para remover o esmalte e expor a dentina. Os dentes foram aleatoriamente distribuídos em três grupos experimentais de acordo com o sistema adesivo aplicado: Single Bond 2 (SB2) (3M ESPE), Easy One (EO) (3M ESPE) and Clearfil SE Bond (CSE) (Kuraray). Os sistemas adesivos foram aplicados na superfície preparada de acordo com as instruções do fabricante e restaurados usando um compósito resinoso (Filtek Supreme, 3M ESPE). Após estocagem em água deionizada por 24 horas (37°C), os dentes foram seccionados no sentido longitudinal (mesio-distal e vestíbulo-lingual) para obter espécimes com uma aparência similar a palitos com área de 0,8 mm2 (±0,1mm2). Os espécimes foram tracionados usando uma máquina de teste universal (Instron 4411, Corona, CA, USA) com célula de carga de 500N a uma velocidade de 0,5 mm/min. Os padrões de fratura foram observados em MEV (JEOL, JSM - 5600 LV, Scanning Electron Microscope, Tokyo, Japan). Os dados foram analisados pelo teste ANOVA para dois fatores (p?0,05). Nenhuma diferença estatística significativa foi encontrada entre os sistemas adesivos e entre os grupos de dentes irradiados in vivo (SB= 44,66±10.12; EO= 41,48±12.71; CSE= 46,01±6.98) e grupo controle (SB= 39,12±9.51; EO= 42,40±6.66; CSE= 36,58±7.06). Todos os grupos apresentaram predominantemente padrão de fratura mista, com fraturas na base da camada híbrida, coesiva na camada híbrida e coesiva no adesivo. A radioterapia realizada in vivo não afetou a resistência de união à dentina aos sistemas adesivos utilizados no estudo
Abstract: This study evaluated the influence of irradiation on dentin bond strength of the extracted teeth of patients who underwent radiotherapy. Eighteen caries-free human incisors were extracted from healthy patients (control group) and eighteen incisors from patients submitted to radiotherapy. The buccal surfaces of each tooth were grounded to remove enamel and expose dentin. Teeth were randomly assigned to three experimental groups according to the adhesive system employed: Single Bond 2 (SB2) (3M ESPE), Easy One (EO) (3M ESPE) and Clearfil SE Bond (CSE) (Kuraray). The adhesive systems were applied to the prepared surface according to manufacturers' instructions and were restored using composite resin (Filtek Supreme, 3M ESPE). After 24 hours in deionized water storage (37oC), teeth were longitudinal (mesio-distal and buccal-lingual) cut to obtain beam specimens with a cross-section area of 0.8 (± 0.1mm2). Specimens were tested in tension using a universal testing machine (Instron 4411, Corona, CA, USA) with 500 N load cell at a cross-speed of 0.5mm/min. Fracture patterns were observed under SEM (JEOL, JSM - 5600 LV, Scanning Electron Microscope, Tokyo, Japan). Data were analyzed by Two-way ANOVA (p?0.05). No statistically significant difference was found among adhesive systems or between the irradiated group in vivo (SB= 44.66±10.12; EO= 41.48±12.71; CSE= 46.01±6.98) and the control group (C/SB= 39.12±9.51; C/EB= 42.40±6.66; C/CSE= 36.58±7.06). All groups presented a predominance of mix fractures with the hybrid layer inner base, cohesive in hybrid layer and cohesive in adhesive. Radiotherapy in vivo did not affect dentin bond strength for the adhesive materials tested in this study
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários
8
Carvalho, Cláudio Antonio Talge [UNESP]. "Avaliação in vitro da resistência estrutural em dentes fragilizados utilizando reforços intra-radiculares." Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/114073.
Анотація:
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000153365.pdf: 4243096 bytes, checksum: 4ac8a630a1606f01e62807e3baafb495 (MD5)Dentes com rizogênese incompleta quando sofrem trauma com conseqüente necrose pulpar permanecem com suas paredes dentinárias finas e fragilizadas, tornando-se mais suscetiveis a reincidências de fraturas. A proposta deste trabalho foi avaliar através do teste de compressão a resistência à fratura de dentes bovinos fragilizados que receberam reforços intra-radiculares com resina composta ou pino de fibra de zircônia. Para tanto, utilizou-se 56 dentes bovinos, os quais tiveram suas coroas seccionadas padronizando o tamanho das raízes em 30mm. Os dentes foram divididos em quatro grupos experimentais (14 dentes} e, com exceção do grupo 04 (Controle negativo), todos os canais radiculares foram preparados biomecanicamente até o instrumento de nº 80 e alargados com brocas Gates-Glidden nos 3, 4, 5 e 6 até 20mm de profundidade. A porção coronária foi alargada com broca diamantada tronco cônica nº 721 até a junção cemento-esmalte vestibular e, com broca diamantada tronco cônica nº 716, realizou-se a fragilização das paredes dentinárias do canal radicular a 20mm de profundidade, deixando aproximadamente 2mm de espessura em cada parede. Após, as raízes foram divididas em grupos: grupo 01-receberam reforço intra-radicular com resina composta, fotopolimerizada com o auxílio do sistema Luminex , seguida da obturação do canal; grupo 02-obturação do canal deixando os 10mm apicais com material obturador, e reforço intra-radicular com pino de fibra de zircõnia cimentado com cimento resinoso; o grupo 03-(Controle positivo) não recebeu reforço intra-radicular e foi obturado pela técnica da condensação lateral ativa; no grupo 04-(Controle negativo), os dentes não foram fragilizados. Os espécimes foram embutidos em blocos metálicos, os quais foram adaptados a um dispositivo cilíndrico, de modo que os espécimes foram fixados a 45°. Este dispositivo foi adaptado a um...
lmmature teeth when suffer trauma with consequent necrosis pulpar they stay with its dentinal walls thin and brittle, becoming more susceptible to the second injuries. The purpose of this work is to evaluate through the compression test, the resistance to fracture of teeth bovine brittleness that received reinforcements within the root canal with composite resin or pins of zircônia fiber. lt was used 56 bovine teeth, which had its crowns sectioned in the medium third standardizing the size of the specimens in 30mm of length. The teeth were divided in four experimental groups (14 teeth) and, except for the group 04 (negative control), all the root canal was instrumented to #80 and enlarged firstly with drills Gates-Glidden numbers 3, 4, 5 and 6 to 20mm of depth, after, lhe coronary portion was enlarged with the conical drill number 721 until the cementoenamel junction facial and, with lhe conical drill number 716, the brittleness of the dentinal walls of the root canal at 20mm of depth, leaving 2mm of thickness approximately in each wall. After, the specimens of the group 01 received reinforcement within the root canal with composite resin, that was cured by aid of the Luminex system and, after, they were obturated; in lhe group 02, the specimens were obturated. Just leaving the 10mm apical with material, and they received reinforcement within the root canal with zircônia fiber pins cemented with resinous cement; the group 03 (positive control) it didn't received reinforcement within the root canal and it was obturated by the technique of the active lateral condensation; in the group 04 (negative control), the teeth were not brittleness. After, all the specimens were embedded with acrylic resin chemically activated, in metallic blocks, which were adapted to a cylindrical device, so that the specimens were fractured by load in angle of 45°. This device was adapted to a lnstron machine, ...
9
Penina, Patricia de Oliveira. "Análise microscópica de capeamento pulpar direto com diferentes materiais em dentes humanos." Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=562.
Анотація:
O capeamento pulpar direto busca preservar a vitalidade pulpar. Este trabalho apresenta a resposta tecidual de polpas humanas ao capeamento pulpar direto com o Agregado de Trióxido Mineral (MTA) comparado com o hidróxido de cálcio. Foram utilizados 20 pré-molares de dez pacientes com extração indicada para tratamento ortodôntico. Todos os dentes apresentavam vitalidade pulpar e neles foram feitos capeamentos pulpares diretos com MTA ou com o hidróxido de cálcio. Os dentes foram extraídos num período de 14 dias ou 45 dias, estabelecendo os seguintes grupos experimentais: Ca(OH) 14 dias; Ca(OH) 45 dias; MTA 14 dias e MTA 45 dias. Estes dentes foram analisados microscopicamente por dois examinadores treinados. Os dados obtidos foram tabulados, utilizando-se o teste Kappa para observar o grau de concordância entre os examinadores. Para avaliação comparativa entre as respostas citotóxicas dos materiais testados foi aplicado o teste não paramétrico Kruskal-Wallis e o teste de Dunn para comparações individuais e identificação da significância dos achados. Na análise dos resultados não houve diferença estatisticamente significante entre os grupos nos períodos experimentais de 14 e 45 dias, e nem na resposta inflamatória pulpar frente ao hidróxido de cálcio quando comparado ao MTA. Quanto à espessura e à organização da barreira dentinária reparatória com o hidróxido de cálcio, quando comparado com o MTA também não apresenta diferença estatisticamente significante. Conclui-se que o MTA satisfaz os requisitos de um material capeador pulpar em dentes de humanos, apresentando propriedades físicas e biológicas que o indicam para este tratamento.The direct dental pulp capping aims to preserve the pulp vitality. This work shows the tissue response from human pulps to that procedure with the Mineral Trioxide Agregate (MTA) compared to calcium hydroxide - Ca(OH)2. Twenty premolars from 10 patients with extraction indicated to orthodontic treatment were used. All teeth showed pulp vitality and were treated with direct dental pulp capping with MTA or with calcium hydroxide. The teeth have been extracted within 14 or 45 days, stablishing the following experimental groups: Ca(OH)2 14 days; Ca(OH)2 45 days; MTA 14 days; and MTA 45 days. These teeth were analyzed under microscopy by two observers trained. The data obtained were put in table using the Kappa test to note the agreement degree between the observers. For the comparative assessment between the citotoxic response from material tested has been applied the non-paired Kruskal-Wallis test, and the Dunns test for individual comparisons and identifying the significance of findings. In the analysis of results there had no statistically significant difference between the groups in experimental periods of 14 days and 45 days, not even in the pulp inflammatory response to calcium hydroxide when compared to MTA. The thickness and arrangement of the healing dentin barrier faced with calcium hydroxide, when compared to MTA, also showed no statistically significant difference. It may be concluded that the MTA fulfils the requirements of pulp capping material in human teeth showing biological and physical properties that indicate it for this treatment.
10
Lopes, Murilo Baena. "Analise estrutural e mecanica de dentes bovinos relacionados a testes de união adesiva." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290104.
Анотація:
Orientador: Simonides ConsaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O propósito deste estudo foi: 1 - Comparar os valores de resistência de união esmalte e dentina humanos com os valores obtidos em dentes bovinos, utilizando dois sistemas de união com princípios de atuação distintos; 2 -Comparar as dimensões tubulares e distribuição na dentina humana e bovina; 3-Comparar duas técnicas (confocal e microscopia óptica) para determinar a microinfiltração em dentes bovinos e humanos para sistemas adesivos. Para o teste de resistência de união, a dentina e o esmalte humano e bovino apresentaram valores equivalentes para o Clearfil Liner Bond 2V. O Scotchbond Multi-Purpose não mostrou diferença estatística em esmalte, porém em dentina o substrato bovino mostrou maiores valores de união que o humano. Quando analisado o diâmetro tubular, a dentina bovina superficial e média mostrou diâmetros estatisticamente maiores que para a dentina humana superficial e média. Não se encontrou diferença estatística entre o diâmetro tubular em dentina humana e bovina em dentina profunda. A densidade dos túbulos dentinários foi estatisticamente maior em dentina humana que em dentina bovina. No teste de microinflitração, quando dente bovino foi utilizado, o Scotchbond apresentou estatisticamente mais infiltração que o Clearfil. Para o dente humano não foi encontrada diferença estatística. Quando escores foram analisados, o Scotchbond não apresentou diferenças para o Clearfil, entretanto este apresentou estatisticamente menos infiltração em dente bovino que em dente humano quando o microscópio óptico foi utilizado. Microscópio confocal mostrou maior especificidade para o corante e limites de microinfiltração mais nítidos. Com o substrato bovino nem sempre se encontrou resultados equivalentes em teste de união com o dente humano. A estrutura dentinária mostrou-se diferente entre dentes humanos e bovinos. O dente bovino não seria o mais adequado para testes de microinfiltração
Abstract: The purpose of this study was: 1 - To compare shear bond strength values obtained in human enamel and dentin with the values obtained in bovine teeth using two adhesive systems with different actions; 2- To compared the tubular dimensions and distribution of human dentine and bovine dentine; 3 - To compare two techniques (confocal and optical microscopies) for determining microleakage in human and bovine teeth for adhesive bond systems. For shear bond strength, the bovine and the human dentin and enamel had equivalent values for Clearfil Liner Bond 2V. Scotchbond Multi-Purpose had no statistical differences on enamel, but on dentin, the bovine substrate showed higher bond strength values than the human one. Bovine dentine tubular diameter for superficial and middle dentine was significantly greater than for human superficial and middle dentine. There was no significant difference in tubular diameter between human and bovine deep dentine. The density of dentine tubules is significantly greater in human dentine than in bovine dentine. When bovine teeth were used, Scotchbond showed statistically higher mean penetration than Clearfil. When human teeth were used no difference was found. For microleakage test, when bovine teeth were used, Scotchbond showed statistically higher mean penetration than Clearfil. When human teeth were used no difference was found. When scores were analyzed, Scotchbond showed no difference to Clearfil, however Clearfil showed statistically less infiltration in bovine teeth than in human teeth when optical microscopy was used. Confocal microscopy showed higher sensibility for the stain and clearer leakage limits. The bovine teeth not always show the same pattern of results of human teeth in shear bond test. The dentinal structure showed different between human and bovine substrates. Bovine teeth may be not suitable for adhesive microleakage tests
Doutorado
Materiais Dentarios
Doutor em Materiais Dentários
Книги з теми "Denses materials":
1
Fukuda, Atsuo. Kyōyū densei ekishō disupurei to zairyō: Ferroelectric liquid crystal display and its materials. 8th ed. Tōkyō: Shī Emu Shī, 2001.
2
Sentā, Densen Sōgō Gijutsu. Eko zairyō no saisentan: Densen ni okeru nonharogen nannen zairyō no kaihatsu jōkyō. 8th ed. Tōkyō: Enu Tī Esu, 2004.
3
Schwille, Friedrich. Dense chlorinated solvents in porous and fractured media: Model experiments. Chelsea, MI: Lewis Publishers, 1988.
4
Pankow, James F. Dense chlorinated solvents and other DNAPLs in groundwater: History, behavior, and remediation. Portland, OR: Waterloo Press, 1996.
5
Thompson, Gary. Investigation of the Bailey method for the design and analysis of dense-graded HMAC using Oregon aggregates: Final report. Salem, OR: Oregon Dept. of Transportation, Research Unit, 2006.
6
International Conference on Radiative Properties of Hot Dense Matter (2nd 1983 Sarasota, Fla.). Proceedings of the 2nd International Conference on Radiative Properties of Hot Dense Matter : Sarasota, Florida, Oct 31-NOv 4, 1983. Edited by Davis J. 1935-. Singapore: World Scientific, 1985.
7
Phillips, Allan R. Type material of birds in the Denver Museum of Natural History. Denver, Colo: Denver Museum of Natural History, 1991.
8
LeGeros, Racquel Zapanta. Calcium phosphates in oral biology and medicine. Basel: Karger, 1991.
9
O'Connor, Jane. La dent précieuse. Toronto (Ontation): Éditions Scholastic, 2012.
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Hixson, Walter L. Parting the curtain: Propaganda, culture, and the Cold War, 1945-1961. New York: St. Martin's Press, 1997.
Частини книг з теми "Denses materials":
1
Wang, Yanfei, Chongxiang Huang, Yusheng Li, Fengjiao Guo, Qiong He, Mingsai Wang, Xiaolei Wu, Ronald O. Scattergood, and Yuntian Zhu. "Dense Dispersed Shear Bands in Gradient-Structured Ni." In Heterostructured Materials, 251–79. New York: Jenny Stanford Publishing, 2021. http://dx.doi.org/10.1201/9781003153078-18.
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Iyetomi, Hiroshi, and Setsuo Ichimaru. "Hypernetted Chain Analyses of Dense Plasmalike Materials." In Condensed Matter Theories, 141–47. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0917-8_16.
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Hilfer, R., S. Alexander, and R. Bruinsma. "On Dense Branching Phase Separation." In Time-Dependent Effects in Disordered Materials, 417–20. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-7476-3_43.
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Dancer, C. E. J., R. I. Todd, and C. R. M. Grovenor. "Ceramic Processing for Dense Magnesium Diboride." In Ceramic Materials for Energy Applications, 109–20. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118095386.ch12.
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Erofeev, Vladimir I., and Igor S. Pavlov. "A 2D Lattice with Dense Packing of the Particles." In Advanced Structured Materials, 35–54. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60330-4_2.
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Mellor, Mary. "Gender and Sustainability – A Material Relation." In Nachhaltigkeit anders denken, 61–76. Wiesbaden: Springer Fachmedien Wiesbaden, 2014. http://dx.doi.org/10.1007/978-3-658-08106-5_6.
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Yeritsyan, H. N. "Material Science Application on CANDLE." In Electron-Photon Interaction in Dense Media, 365–71. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0367-4_31.
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Erofeev, Vladimir I., and Igor S. Pavlov. "Application of the 2D Models of Media with Dense and Non-dense Packing of the Particles for Solving the Parametric Identification Problems." In Advanced Structured Materials, 83–107. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60330-4_4.
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Wang, Ling, Fu Shen Li, Hui Zhu Zhou, Hui Xia, Mei Yang, and Li Fen Li. "Limiting Current Oxygen Sensors with LSF as Dense Diffusion Barrier." In Key Engineering Materials, 417–19. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.417.
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Erofeev, Vladimir I., and Igor S. Pavlov. "A Two-Dimensional Lattice with Non-dense Packing of Particles." In Advanced Structured Materials, 55–81. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60330-4_3.
Тези доповідей конференцій з теми "Denses materials":
1
Tordesillas, Antoinette, Masami Nakagawa, and Stefan Luding. "Thermomicromechanics of dense granular materials." In POWDERS AND GRAINS 2009: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON MICROMECHANICS OF GRANULAR MEDIA. AIP, 2009. http://dx.doi.org/10.1063/1.3179977.
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Alexander, Chris, and Julian Bedoya. "Repair of Dents Subjected to Cyclic Pressure Service Using Composite Materials." In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31524.
Анотація:
For the better part of the past 15 years composite materials have been used to repair corrosion in high pressure gas and liquid transmission pipelines. This method of repair is widely accepted throughout the pipeline industry because of the extensive evaluation efforts performed by composite repair manufacturers, operators, and research organizations. Pipeline damage comes in different forms, one of which involves dents that include plain dents, dents in girth welds and dents in seam welds. An extensive study has been performed over the past several years involving multiple composite manufacturers who installed their repair systems on the above mentioned dent types. The primary focus of the current study was to evaluate the level of reinforcement provided by composite materials in repairing dented pipelines. The test samples were pressure cycled to failure to determine the level of life extension provided by the composite materials relative to a set of unrepaired test samples. Several of the repaired dents in the study did not fail even after 250,000 pressure cycles were applied at a range of 72% SMYS. The results of this study clearly demonstrate the significant potential that composite repair systems have, when properly designed and installed, to restore the integrity of damaged pipelines to ensure long-term service.
3
Cundiff, Steven T., Justin M. Shacklette, and Virginia O. Lorenz. "Interaction effects in optically dense materials." In Symposium on Integrated Optics, edited by Hongxing Jiang, Kong-Thon F. Tsen, and Jin-Joo Song. SPIE, 2001. http://dx.doi.org/10.1117/12.424728.
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Rajangam, K., M. Mithra, B. Monisa, S. Monisha, T. Oveya, and B. Balraj. "Yielding Power from Dissipation of Dense Materials." In 2019 5th International Conference on Advanced Computing & Communication Systems (ICACCS). IEEE, 2019. http://dx.doi.org/10.1109/icaccs.2019.8728375.
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Kutschke, Walter G., William Petersen, and John Meyers. "Rock Slope Protection System for Differential Weathering Materials." In Geo-Denver 2007. Reston, VA: American Society of Civil Engineers, 2007. http://dx.doi.org/10.1061/40905(224)9.
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Amini Manesh, Navid, Kevin R. Coffey, and Ranganathan Kumar. "Experimental and Numerical Study of Dense Layered Nano-Energetic Materials." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43670.
Анотація:
This paper deals with the reaction of dense Metastable Intermolecular Composite (MIC) materials. The energy density of MIC nanocomposite materials is much higher than that of conventional energetic materials. The reaction of a multilayer thin film of aluminum and copper oxide has been studied by varying the substrate material and thicknesses, to vary the heat loss during the reaction of the MIC material. The in-plane speed of propagation of the reaction was experimentally determined using a time of-flight technique. The experiment shows that the reaction is completely quenched for a silicon substrate having an intervening silica layer of less than 200 nm. The speed of reaction seems to be constant at 40 m/s for silica layers with thickness greater than 1 μm. Different substrate material such as glass was also used. A numerical analysis of the thermal transport from the reacting film shows that the temperature profiles become self similar for substrate thicknesses larger than 1 μm., the maximum temperature stays constant for both silica and composite silica/silicon substrates, showing the effectiveness of the composite substrates to control the heat lost from the reaction, both experimentally and numerically.
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Ma, Li, Tony F. Zahrah, and Richard Fields. "Processing and Simulation of Consolidation of Amorphous Aluminum-Based Powder Material." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41647.
Анотація:
Amorphous aluminum-based materials are light yet much stronger than conventional materials, which offers opportunities in aerospace applications. However, processing the aluminum-based powder into a bulk amorphous material requires relatively low temperature and high pressure, which presents significant challenges. A two-step approach is being explored to reach the goal of a fully dense bulk amorphous or partially amorphous material. First, isostatic pressing is used to partially consolidate the material. Second, extrusion is used to take the partially dense material to full density. Process models are used to design the extrusion process, including the extrusion ratio and extrusion length, to limit the temperature increase during extrusion as a result of adiabatic heating, and to avoid excessive heating to limit devitrification of the amorphous material. A parametric study of extrusion parameters was completed and processing parameters were recommended. The use of process modeling is aimed at understanding the results from the extrusion experiments and limiting the number of iterations during extrusion.
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Royter, Y., P. R. Patterson, J. C. Li, K. R. Elliott, T. Hussain, M. F. Boag-O'Brien, J. R. Duvall, et al. "Dense heterogeneous integration for InP Bi-CMOS technology." In Related Materials (IPRM). IEEE, 2009. http://dx.doi.org/10.1109/iciprm.2009.5012453.
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Iures, Liana. "BUILDING�MATERIALS�REALISED�WITH�DENSE�SLURRY�FROM�FLY�ASH." In SGEM2012 12th International Multidisciplinary Scientific GeoConference and EXPO. Stef92 Technology, 2012. http://dx.doi.org/10.5593/sgem2012/s21.v4002.
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Meyer, Nico. "Interacting Threats Mitigated: Carbon Composite System’s Ability to Restore/Increase Pipeline Strength." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63790.
Анотація:
Fiber Reinforced Polymers (FRPs), a qualified structural building material for several industries, have recently demonstrated additional validation in pressure pipeline applications. With validated durability’s of their own, glass and carbon fiber reinforced polymers (GFRP and CFRP) have demonstrated significant ability to prevent and arrest corrosion in steel and concrete applications while increasing/renewing structural capacities of corroding elements. Although other coatings prevent deterioration of ferrous materials, CFRP and GRFP applications can reinforce and/or effectively replace the pipeline using the existing pipe as a composite form. GFRP and CFRP applications have proven ability in external applications of dented and artificially corroded pressure pipelines with interacting threats of girth and seam welds. The repair systems received cyclic loading up to 72% of the specified minimum yield strength and tested beyond 100,000 and 370,000 pressure cycles without failure for dents and simulated corrosion, respectively. This paper will provide a quick overview of relevant testing on GFRP and CFRP application for corrosion mitigation/rehabilitation with more detail on the recent validation of FRP applications for dented and corroded pressure pipes.
Звіти організацій з теми "Denses materials":
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Sundaresan, Sankaran, Gabriel I. Tardos, and Shankar Subramaniam. Rheological Behavior of Dense Assemblies of Granular Materials. Office of Scientific and Technical Information (OSTI), March 2011. http://dx.doi.org/10.2172/1026503.
2
Coffey, Kevin R. Reaction Mechanisms and Velocity in Dense, Layered, Nanoenergetic Materials. Fort Belvoir, VA: Defense Technical Information Center, June 2008. http://dx.doi.org/10.21236/ada636946.
3
Tordesillas, Antoinette. Multiscale Phenomena in the Solid-Liquid Transition State of a Granular Material: Analysis and Modelling of Dense Granular Materials. Fort Belvoir, VA: Defense Technical Information Center, September 2011. http://dx.doi.org/10.21236/ada574174.
4
Buettner-Garrett, Josh, Heather Platt, and Brian Francisco. Energy Dense Batteries Based on Highly Conductive Solid Electrolyte and Cathode Materials. Office of Scientific and Technical Information (OSTI), July 2018. http://dx.doi.org/10.2172/1460743.
5
Munir, Z. A. Mechanoelectrically Activated Synthesis of Dense, Bulk Nanostructured, Complex Crystalline and Glassy Hard Materials. Fort Belvoir, VA: Defense Technical Information Center, April 2005. http://dx.doi.org/10.21236/ada435086.
6
Dr. Mark S. Klima and Dr. Barbara J. Arnold. ULTRASONICALLY-ENHANCED DENSE-MEDIUM CYCLONING FOR FINE COAL AND COAL REFUSE IMPOUNDMENT MATERIALS. Office of Scientific and Technical Information (OSTI), August 2001. http://dx.doi.org/10.2172/821140.
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Dubois, Diego, Amirali Eskandariyun, Suprabha Das, Andriy Durygin, and Zhe Cheng. Flash Sintering of Commercial Zirconium Nitride Powders. Florida International University, October 2021. http://dx.doi.org/10.25148/mmeurs.009777.
Анотація:
Flash sintering is an electrical field-assisted densification technique that requires passing a current through a ceramic powder compact. Pressure-assisted flash sintering of commercially available Zirconium Nitride (ZrN) powders has been demonstrated. Near fully dense samples can be obtained within a short period of time. The influences of parameters such as electrical field strength, voltage ramping rate, current limit, external pressure, pre-heating, and holding time on the onset of the flash event were investigated. Some post-flash sintered samples were subjected to the same condition to observe if the material would experience repeated flash. In addition, material properties such as density and hardness were measured and correlated with SEM and XRD. Implications of the observations on underlying flash sintering mechanism will also be discussed.
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Gibson, David Jeremy. A High-Energy, Ultrashort-Pulse X-Ray System for the Dynamic Study of Heavy, Dense Materials. Office of Scientific and Technical Information (OSTI), January 2004. http://dx.doi.org/10.2172/15011626.
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Qamhia, Issam, Erol Tutumluer, and Han Wang. Aggregate Subgrade Improvements Using Quarry By-products: A Field Investigation. Illinois Center for Transportation, June 2021. http://dx.doi.org/10.36501/0197-9191/21-017.
Анотація:
This report presents a case study for constructing aggregate subgrade improvement (ASI) layers using quarry by-product aggregates (QBA), a quarry mix of large primary crushed rocks (PCR) and sand-sized quarry fines. The construction took place at Larry Power Road in Bourbonnais Township in Kankakee County, Illinois, where the Illinois Department of Transportation placed two QBA mixes. The first mix (QBA_M1) consisted of 45% quarry by-products and 55% railroad ballast–sized 3×1 PCR. The second mix (QBA_M2) consisted of 31% and 69% quarry by-products and PCR, respectively. Two conventional ASI sections were also constructed conforming to Illinois Department of Transportation’s CS02 gradation. All sections consisted of a 9 in. (229 mm) QBA/PCR layer topped with a 3 in. (76 mm) dense-graded capping layer. Laboratory studies preceded the construction to recommend optimum quarry by-product content in the QBA materials and construction practice. The Illinois Center for Transportation research team monitored the quality and uniformity of the construction using nondestructive testing techniques such as dynamic cone penetrometer, lightweight deflectometer, and falling weight deflectometer. The segregation potential was monitored by visual inspection and imaging-based techniques. Short-term field evaluation of the constructed QBA layers, particularly QBA_M2 with a 31% quarry by-product content, showed no evidence of abnormal segregation and did not jeopardize the structural integrity of the QBA ASI layers, which had slightly lower but comparable strength and stiffness profiles to the conventional ASI sections. The use of QBA materials in ASI was field validated as a sustainable construction practice to provide stable pavement foundation layers.
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Nantung, Tommy E., Jusang Lee, John E. Haddock, M. Reza Pouranian, Dario Batioja Alvarez, Jongmyung Jeon, Boonam Shin, and Peter J. Becker. Structural Evaluation of Full-Depth Flexible Pavement Using APT. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317319.
Анотація:
The fundamentals of rutting behavior for thin full-depth flexible pavements (i.e., asphalt thickness less than 12 inches) are investigated in this study. The scope incorporates an experimental study using full-scale Accelerated Pavement Tests (APTs) to monitor the evolution of each pavement structural layer's transverse profiles. The findings were then employed to verify the local rutting model coefficients used in the current pavement design method, the Mechanistic-Empirical Pavement Design Guide (MEPDG). Four APT sections were constructed using two thin typical pavement structures (seven-and ten-inches thick) and two types of surface course material (dense-graded and SMA). A mid-depth rut monitoring and automated laser profile systems were designed to reconstruct the transverse profiles at each pavement layer interface throughout the process of accelerated pavement deterioration that is produced during the APT. The contributions of each pavement structural layer to rutting and the evolution of layer deformation were derived. This study found that the permanent deformation within full-depth asphalt concrete significantly depends upon the pavement thickness. However, once the pavement reaches sufficient thickness (more than 12.5 inches), increasing the thickness does not significantly affect the permanent deformation. Additionally, for thin full-depth asphalt pavements with a dense-graded Hot Mix Asphalt (HMA) surface course, most pavement rutting is caused by the deformation of the asphalt concrete, with about half the rutting amount observed within the top four inches of the pavement layers. However, for thin full-depth asphalt pavements with an SMA surface course, most pavement rutting comes from the closet sublayer to the surface, i.e., the intermediate layer. The accuracy of the MEPDG’s prediction models for thin full-depth asphalt pavement was evaluated using some statistical parameters, including bias, the sum of squared error, and the standard error of estimates between the predicted and actual measurements. Based on the statistical analysis (at the 95% confidence level), no significant difference was found between the version 2.3-predicted and measured rutting of total asphalt concrete layer and subgrade for thick and thin pavements.