Bibliografias temáticas / Carbon segregation

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Literatura científica selecionada sobre o tema "Carbon segregation"

Autor: Grafiati

Publicado: 1 de fevereiro de 2025

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Artigos de revistas sobre o assunto "Carbon segregation"

Tang, Hai Yan, Hong Bin Wang, Hai Shun Li, Jing She Li e Qing Guo Wang. "Researches on the Behavior of Carbon and Sulfur Segregations of 82B Billet". Advanced Materials Research 399-401 (novembro de 2011): 206–10. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.206.

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The behavior of carbon and sulfur segregations of 82B hard wire steel produced under different continuous casting conditions has been systematically studied by the combination of field trial and laboratory analysis. The results showed three factors such as superheat degree, casting speed and F-EMS which influenced the segregation of billet worked differently with the variations of inner positions of the billet and segregation elements. For the central segregations of carbon and sulfur, the dominant factor was casting speed. Under high casting speed, proper increase of secondary cooling intensity could effectively decrease carbon and sulfur segregations of billet, especially for the central position of billet. The hydraulic simulation of the tundish showed the optimal casting speed should be 1.8m/min.

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Oehme, M., M. Bauer, C. P. Parry, G. Eifler e E. Kasper. "Carbon segregation in silicon". Thin Solid Films 380, n.º 1-2 (dezembro de 2000): 75–77. http://dx.doi.org/10.1016/s0040-6090(00)01533-9.

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Chen, Jing Hu, e Xiao Hua Jie. "Study of Centerline Segregation in Alloy Tool Steel on CSP Technology". Advanced Materials Research 197-198 (fevereiro de 2011): 1744–48. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1744.

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After studying the slab of the CSP, the composition segregation and the finished products, we drew the conclusion that the low magnification of CSP thin slab is denser, columnar grain more developed; Loose and segregation exist while the segregation is smaller than traditional one. From the surface to the center, obvious carbon segregation exists: nearby the center is negative segregation and in the center is positive segregation. With the increase of carbon content, carbon segregation also increases. The carbon content of tundish is different from that of rolled steel coil --namely, the carbon content of the rolled coil is significantly lower.

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Ewels, C. P., D. Erbahar, Ph Wagner, X. Rocquefelte, R. Arenal, P. Pochet, M. Rayson, M. Scardamaglia, C. Bittencourt e P. Briddon. "Nitrogen segregation in nanocarbons". Faraday Discuss. 173 (2014): 215–32. http://dx.doi.org/10.1039/c4fd00111g.

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We explore the behaviour of nitrogen doping in carbon nanomaterials, notably graphene, nanotubes, and carbon thin films. This is initially via a brief review of the literature, followed by a series of atomistic density functional calculations. We show that at low concentrations, substitutional nitrogen doping in the sp²-C graphenic basal plane is favoured, however once the nitrogen concentration reaches a critical threshold there is a transition towards the formation of the more thermodynamically-favoured nitrogen terminated ‘zigzag’ type edges. These can occur either via formation of finite patches (polycyclic aromatic azacarbons), strips of sp² carbon with zigzag nitrogen edges, or internal nitrogen-terminated hole edges within graphenic planes. This transition to edge formation is especially favoured when the nitrogen can be partially functionalised with, e.g. hydrogen. By comparison with available literature results, notably from electron energy loss spectroscopy and X-ray spectroscopy, the current results suggest that much of the nitrogen believed to be incorporated into carbon nanoobjects is instead likely to be present terminating the edges of carbonaceous impurities attached to nanoobject's surface. By comparison to nitrogen-doped tetrahedrally amorphous carbon, we suggest that this transition at around 10–20% nitrogen concentration and above towards sp² coordination via internal nitrogen-terminated edge formation may be a general property of nitrogen-doped carbon materials.

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Liu, Daiwei, Guifang Zhang, Jianhua Zeng e Xin Xie. "Numerical Simulation of Segregation in Slabs under Different Secondary Cooling Electromagnetic Stirring Modes". Materials 17, n.º 11 (3 de junho de 2024): 2721. http://dx.doi.org/10.3390/ma17112721.

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Secondary cooling electromagnetic stirring (S-EMS) significantly impacts the internal quality of continuous casting slabs. In order to investigate the effects of S-EMS modes on segregation in slabs, a three-dimensional numerical model of the full-scale flow field, solidification, and mass transfer was established. A comparative analysis was conducted between continuous electromagnetic stirring and alternate stirring modes regarding their impacts on steel flow, solidification, and carbon segregation. The results indicated that adopting the alternate stirring mode was more advantageous for achieving uniform flow fields and reducing the disparity in solidification endpoints, thus mitigating carbon segregation. Specifically, the central carbon segregation index under continuous stirring at 320 A was 1.236, with an average of 1.247, while under alternate stirring, the central carbon segregation index decreased to 1.222 with an average of 1.227.

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Li, Pengchao, Guifang Zhang, Peng Yan, Nan Tian e Zhenhua Feng. "Numerical and Experimental Study on Carbon Segregation in Shaped Billet of Medium Carbon Steel with Combined Electromagnetic Stirring". Materials 16, n.º 23 (30 de novembro de 2023): 7464. http://dx.doi.org/10.3390/ma16237464.

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Carbon segregation is the major and classical internal defect in the continuous casting process of carbon steel. Based on the combined electromagnetic stirring equipment for new billet in a steel plant, China, the influence of combined electromagnetic stirring (M-EMS + F-EMS) on the carbon segregation of 300 mm × 340 mm special-shaped billet was studied via numerical simulation and on-site industrialization tests. The Lorentz force and carbon solute distribution were simulated under different EMS parameters. The formation mechanism of the carbon segregation of medium carbon steel with different combined electromagnetic stirring processes was analyzed. The results show that: (1) with the combined action of “solute flushing” effect and gravity, the carbon concentration in the loose side of the medium carbon steel casting billet is gradually lower than the fixed side, while the carbon concentration on the fixed side gradually accumulates more; and (2) under the action of combined electromagnetic stirring, the segregation index of casting billet could be controlled to remain between 0.96–1.05 and shows an increasing change in solidification from the skin to the center. When the current and frequency of M-EMS are 250 A and 2.0 Hz and the F-EMS are 180 A and 8.0 Hz, the carbon segregation defects in the special-shaped (300 mm × 340 mm) casting billet can be significantly improved.

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Potekhina, N. D., N. R. Gall’, E. V. Rut’kov e A. Ya Tontegode. "Carbon segregation on a tungsten surface". Physics of the Solid State 45, n.º 4 (abril de 2003): 782–87. http://dx.doi.org/10.1134/1.1569021.

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Janthon, Patanachai, Francesc Viñes, Jakkapan Sirijaraensre, Jumras Limtrakul e Francesc Illas. "Carbon dissolution and segregation in platinum". Catalysis Science & Technology 7, n.º 4 (2017): 807–16. http://dx.doi.org/10.1039/c6cy02253g.

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Density functional studies at show the feasibility of C subsurface incorporation in Platinum occupying tetrahedral sites. A comparative with Ni and Pd highlights that surface relaxation is critical in C dissolution, specially at low-coordinated sites of Pt nanoparticles. Results explain phenomena such as C dissolution and segregation to form graphene from below, and may serve to tune the Pt surface chemical reactivity.

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Mizushima, Ichiro, Eiji Kamiya, Norihisa Arai, Masahisa Sonoda, Masahiko Yoshiki, Shin-ichi Takagi, Mikio Wakamiya et al. "Diffusion and Segregation of Carbon inSiO2Films". Japanese Journal of Applied Physics 36, Part 1, No. 3B (30 de março de 1997): 1465–68. http://dx.doi.org/10.1143/jjap.36.1465.

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Alaoua, D., A. Larere, D. Roptin e G. Saindrenan. "Surface segregation in low carbon steels". Materials Science and Engineering: A 174, n.º 2 (fevereiro de 1994): 187–92. http://dx.doi.org/10.1016/0921-5093(94)91087-1.

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Mais fontes

Teses / dissertações sobre o assunto "Carbon segregation"

Sung, Pil Kyung 1961. "Segregation and structure in continuously cast high carbon steel". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277066.

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After hot rolling, the presense of segregation in the center of wire-rod can lead to a nonuniform transformation, resulting in bands of martensite in the microstructure. This is considered to be a defect, called center-martensite, because it can cause cracks and breaks during wire drawing. To identify the mechanism for the formation of center-martensite in wire-rod, the structure, macrosegregation and microsegregation in unworked billets were characterized. Based on measurements of secondary dendrite arm spacings, cooling rates during solidification were estimated. It appears that the macrosegregation of carbon and manganese in the billets manifests itself as the microsegregation in wire-rod, which is an agent in forming the center-martensite. Thus, electromagnetic stirring is proposed as a means to reduce the macrosegregation in the billet and, thereby, reduce the occurrence of center-martensite in wire-rod.

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Maier, Petra. "Segregation behaviour of phosphorus, manganese and carbon in boiler shell weld materials". Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/35335.

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The work in this thesis has developed theoretical models to predict the microstructural behaviour of weld materials. Three different types of boiler shell weld materials from nuclear power plants have been investigated. The materials considered differ mainly in the manganese concentration and their microstructure after different temperature exposures during industrial use. Element segregation can be predicted according to the typical reactor conditions and therefore the influence of longer life times can be evaluated. Sufficient experimental data have been taken by application of advanced transmission electron microscopes which offer images of high quality. The application of a thermodynamic software package MTDATA to predict the free concentration of each element for model prediction has been. Phosphorus, of great interest because it causes embrittlement, is enhanced at the grain boundary and increases with operating temperature and life time. Its interaction with carbon and manganese is of interest. Site-competition between carbon, phosphorus and manganese has to be applied. These site competition model prediction results fit best to the experimental data.

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Badinier, Guillaume. "The effect of carbon segregation and carbide precipitation on the mechanical response of martensite". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44022.

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The influence of carbon distribution and carbide precipitation on the mechanical properties of the as-quenched and quenched and tempered 300M martensitic steel has been investigated. The microstructure, investigated by transmission electron microscopy (TEM) and three dimensional atom probe tomography (APT) was found to be relatively homogeneous in the as-water-quenched state, but signifi cantly evolved upon tempering and variation of quench rate. This evolution included carbon segregation to dislocations and grain boundaries and carbide precipitation. A simple mean- field precipitation model assuming heterogeneous nucleation onto the dislocations proved to satisfactorily capture the evolution of precipitation upon tempering at 120C and 150C. The material was found to behave, mechanically, as a composite and in accordance, the Bauschinger stress-strain behaviour was successfully modeled using a continuous Masing model. This model, when related to the microstructure, showed that the composite behaviour arose from the mechanical contrast between the laths, this being controlled by the local dislocation density and carbon segregation and/or precipitation onto them. Carbon segregation and carbide precipitation were observed to have a direct impact on alpha in the Taylor-like equation that was shown to control the local yield stress within the laths. When applied to martensites containing various amount of carbon, the model allowed for an empirical assessment of the e ffect of the nominal carbon content on alpha , which was found to be linearly dependent on the nominal carbon content.

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Tran, Tu Anh. "Modelling and experimental study of secondary dendrite arm spacing and micro-segregation in continuously cast high carbon bloom steel". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5635/.

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Massart, Thierry-Jean. "Soudage par diffusion en vue de la realisation de jonctions heterogenes : utilisation du procede de decapage-activation". Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0037.

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Sondage par diffusion teste sur une jonction astroloy (nk17cdat) et in100 (nk15cat) a teneurs en carbone et en titane differentes. Ces jonctions presentent des problemes de segregation sur les surfaces libres

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Gomes, De Aguiar Veiga Roberto. "Computational insights into the strain aging phenomenon in bcc iron at the atomic scale". Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00708423.

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Static strain aging is an important concept in metalurgy that refers to the hardening of a material that has undergone plastic deformation and then is aged for a certain period of time. A theory proposed in the late 1940s by Cottrell and Bilby explains this phenomenon as being caused by the pinning of dislocations by impurities (e.g., carbon atoms in solid solution) that migrate to the vicinity of the line defect. In the course of this PhD work, the atomistic mechanism behind the static strain aging phenomenon in bcc iron has been studied by means of computer simulations. Given the fact that diffusion in the solid state proceeds slowly, thus preventing the use of molecular dynamics at low temperatures (when the effect of the dislocation stress field on carbon diffusion is more pronounced), we have preferentially employed a method coupling molecular statics with atomistic kinetic Monte Carlo. Three major points have been addressed by this thesis: (i) the effect of the stress field of an edge or screw dislocation on a carbon atom diffusing nearby; (ii) the diffusion of a carbon atom in the tight channel found in the dislocation core (pipe diffusion); and (iii) the equilibrium carbon distribution in a Cottrell atmosphere. The main effect of the dislocation stress field outside the dislocation core consists of biasing carbon diffusion, such that some transitions become more likely than others. This effect is expected to drive the early stages of Cottrell atmosphere formation, when the mutual interaction between carbon atoms is negligible. Right in the dislocation core, as expected, carbon was seen to diffuse faster than in the bulk. Carbon concentration in the neighborhood of an edge or a screw dislocation was modeled by an approach based in statistical physics using the binding energies calculated by molecular statics, revealing a good agreement with experimental data obtained by atom probe techniques.

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Aguiar, Veiga Roberto Gomes de. "Computational insights into the strain aging phenomenon in bcc iron at the atomic scale". Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0084/document.

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Le vieillissement statique est un concept important dans la métallurgie qui se réfère à un durcissement de la matière ayant subi une déformation plastique et est ensuite vieilli pendant une certaine période de temps. La théorie proposée dans les années 1940 par Cottrell et Bilby explique ce phénomène comme étant causé par l'épinglage des dislocations par les impuretés (par exemple, les atomes de carbone en solution solide) qui migrent au voisinage du défaut de ligne. Au cours de ce travail de thèse, le mécanisme atomistique responsable du phénomène du vieillissement statique dans le fer alpha a été étudié par des simulations numériques. Etant donné que la diffusion à l'état solide se déroule lentement, l'utilisation de la dynamique moléculaire à basse température (lorsque l'effet du champ de contraintes sur la dislocation de diffusion du carbone est plus prononcé) a été évitée, et nous avons utilisé préférentiellement le couplage de la statique moléculaire avec le Monte-Carlo cinétique atomistique. Trois points principaux ont été abordés dans cette thèse: (i) l'effet du champ de contraintes d'une dislocation coin ou vis sur un atome de carbone qui diffuse à proximité, (ii) la diffusion de l'atome de carbone dans le cour de la dislocation («pipe diffusion»), et (iii) la distribution d'équilibre des atomes de carbone dans une atmosphère de Cottrell. Le principal effet du champ de contrainte de la dislocation à l'extérieur du coeur est de biaiser la diffusion de l'impurité, de sorte que certains sauts (transitions) deviennent plus probables que d'autres. Cet effet va conduire aux premiers stades de la formation de l'atmosphère de Cottrell, lorsque l'interaction mutuelle entre atomes de carbone est négligeable. Au cœur de la dislocation, comme prévu, nos résultats indiquent que le carbone diffuse plus vite que dans le volume. La concentration de carbone dans le voisinage d'une dislocation coin ou vis a été modélisée par une approche de physique statistique en utilisant les énergies de liaison calculées par la statique moléculaire. Cette approche est en bon accord avec les données expérimentales
Static strain aging is an important concept in metalurgy that refers to the hardening of a material that has undergone plastic deformation and then is aged for a certain period of time. A theory proposed in the late 1940s by Cottrell and Bilby explains this phenomenon as being caused by the pinning of dislocations by impurities (e.g., carbon atoms in solid solution) that migrate to the vicinity of the line defect. In the course of this PhD work, the atomistic mechanism behind the static strain aging phenomenon in bcc iron has been studied by means of computer simulations. Given the fact that diffusion in the solid state proceeds slowly, thus preventing the use of molecular dynamics at low temperatures (when the effect of the dislocation stress field on carbon diffusion is more pronounced), we have preferentially employed a method coupling molecular statics with atomistic kinetic Monte Carlo. Three major points have been addressed by this thesis: (i) the effect of the stress field of an edge or screw dislocation on a carbon atom diffusing nearby; (ii) the diffusion of a carbon atom in the tight channel found in the dislocation core (pipe diffusion); and (iii) the equilibrium carbon distribution in a Cottrell atmosphere. The main effect of the dislocation stress field outside the dislocation core consists of biasing carbon diffusion, such that some transitions become more likely than others. This effect is expected to drive the early stages of Cottrell atmosphere formation, when the mutual interaction between carbon atoms is negligible. Right in the dislocation core, as expected, carbon was seen to diffuse faster than in the bulk. Carbon concentration in the neighborhood of an edge or a screw dislocation was modeled by an approach based in statistical physics using the binding energies calculated by molecular statics, revealing a good agreement with experimental data obtained by atom probe techniques

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Bacia, Maria. "Comportement du carbone aux joints de grains du molybdène". Grenoble INPG, 1994. http://www.theses.fr/1994INPG4210.

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La mise en evidence et l'interpretation du role benefique du carbone et du role nefaste de l'oxygene sur la cohesion intergranulaire du molybdene en l'absence de precipitation visible au meb constituaient le but de cette etude. Une methode efficace de purification du molybdene a ete mise au point. Les mesures de la concentration intergranulaire de carbone en fonction de la temperature de carburation et de la teneur volumique ont ete effectuees a l'aide d'un spectrometre auger. Un modele d'enrichissement des joints de grains au cours du refroidissement a ete propose. Les structures des joints purs et contenant des atomes de solute ont ete determinees par des simulations statiques a l'aide de potentiels a n corps calcules en se fondant sur la methode de l'atome immerge (eam). La comparaison des segregations intergranulaires d'oxygene et de carbone (sites de segregation, sequence d'occupation des sites, enthalpies de melange) a ete effectuee pour le cas du joint symetrique de flexion 37 autour de l'axe 100. Les structures atomiques du joint 37 a l'etat pur et a l'etat carbure ont ete observees au microscope electronique a haute resolution. Apres la carburation ne conduisant pas a la formation de precipites mo#2c visibles au meb, la presence d'une phase bidimensionnelle moc#x (x 0,4) formant un film continu au joint a ete mise en evidence. Elle peut etre rendue responsable du renforcement du joint. Sa faible largeur ( 10 a) et son accommodation parfaite aux reseaux cristallographiques des deux grains rendent son observation impossible par des methodes classiques (meb, met), ce qui explique que son existence etait jusqu'a maintenant ignoree. Il n'est pas exclu qu'il s'agisse de la premiere observation d'un etat intermediaire entre la segregation et un compose tridimensionnel discontinu

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Suvar, Erdal. "SiGeC Heterojunction Bipolar Transistors". Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3674.

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Heterojunction bipolar transistors (HBT) based on SiGeC havebeen investigated. Two high-frequency architectures have beendesigned, fabricated and characterized. Different collectordesigns were applied either by using selective epitaxial growthdoped with phosphorous or by non-selective epitaxial growthdoped with arsenic. Both designs have a non-selectivelydeposited SiGeC base doped with boron and a poly-crystallineemitter doped with phosphorous.

Selective epitaxial growth of the collector layer has beendeveloped by using a reduced pressure chemical vapor deposition(RPCVD) technique. The incorporation of phosphorous and defectformation during selective deposition of these layers has beenstudied. A major problem of phosphorous-doping during selectiveepitaxy is segregation. Different methods, e.g. chemical orthermal oxidation, are shown to efficiently remove thesegregated dopants. Chemical-mechanical polishing (CMP) hasalso been used as an alternative to solve this problem. The CMPstep was successfully integrated in the HBT process flow.

Epitaxial growth of Si1-x-yGexCy layers for base layerapplications in bipolar transistors has been investigated indetail. The optimization of the growth parameters has beenperformed in order to incorporate carbon substitutionally inthe SiGe matrix without increasing the defect density in theepitaxial layers.

The thermal stability of npn SiGe-based heterojunctionstructures has been investigated. The influence of thediffusion of dopants in SiGe or in adjacent layers on thethermal stability of the structure has also been discussed.

SiGeC-based transistors with both non-selectively depositedcollector and selectively grown collector have been fabricatedand electrically characterized. The fabricated transistorsexhibit electrostatic current gain values in the range of 1000-2000. The cut-off frequency and maximum oscillation frequencyvary from 40-80 GHz and 15-30 GHz, respectively, depending onthe lateral design. The leakage current was investigated usinga selectively deposited collector design and possible causesfor leakage has been discussed. Solutions for decreasing thejunction leakage are proposed.

Key words:Silicon-Germanium-Carbon (SiGeC),Heterojunction bipolar transistor (HBT), chemical vapordeposition (CVD), selective epitaxy, non-selective epitaxy,collector design, high-frequency measurement, dopantsegregation, thermal stability.

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Wei, Lun-Cun. "Etude de l'incorporation de b, c et o dans gaas prepare par la methode de czochralski (lec), en utilisant l'analyse par activation avec les particules chargees". Paris 6, 1987. http://www.theses.fr/1987PA066031.

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L'incorporation de b et c est d'autant plus faible que la teneur en eau de l'encapsulant (b::(2)o::(3) fondu) est plus grande. B et o segregent toujours en queue de lingot, alors que c segrege en tete dans les lingots riches en gallium et en queue dans les lingots riches en arsenic. Par ailleurs, le coefficient de segregation de b, tout en restant toujours inferieur a 1, prend des valeurs differentes suivant la stoechiometrie de la charge initiale. Ces resultats ouvrent la voie, en relation avec des mesures complementaires (electriques, optiques), d'etudes permettant de preciser l'influence de b, c et o sur les proprietes electroniques de gaas

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Livros sobre o assunto "Carbon segregation"

Cowan, James Richard. The role of stress, microstructure and cooling rate on the grain boundary segregation of phosphorus and carbon in an Fe-P-C alloy. Birmingham: University of Birmingham, 1997.

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Howe, A. A. Segregation and Phase Distribution During Solidification of Carbon, Alloy and Stainless Steels. European Communities / Union (EUR-OP/OOPEC/OPOCE), 1991.

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Mangrum, Benjamin. Existentialism in America. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190909376.003.0003.

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This chapter examines the transformation of postwar liberalism by identifying the development of an American idiom within the existential thought that became influential after the Second World War. I frame the concerns and historical development of American existentialism through the work of Ralph Ellison, Richard Wright, Saul Bellow, and Stanley Donen’s film Funny Face (starring Audrey Hepburn and Fred Astaire). Contrasts are drawn between Ellison and two other writers: Carlos Bulosan and Ann Petry. In addition, the chapter discuses Cold War containment politics, McCarthy era anxieties about communism, changes in perceptions of organized labor, Jim Crow laws, segregation, and cultural attitudes regarding the American welfare state and political action.

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André, Naomi. Black Opera. University of Illinois Press, 2018. http://dx.doi.org/10.5622/illinois/9780252041921.001.0001.

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This is a book about thinking, interpreting, and writing about music in performance that incorporates how race, gender, sexuality, and nation help shape the analysis of opera today. Case-study operas are chosen within the diaspora of the United States and South Africa. Both countries had segregation policies that kept black performers and musicians out of opera. During the civil rights movement and after apartheid, black performers in both countries not only excelled in opera, they also began writing their own stories into the genre. Featured operas in this study span the Atlantic and bring together works performed in the West (the United States and Europe) and South Africa. Focal works are: From the Diary of Sally Hemings (William Bolcom and Sandra Seaton), Porgy and Bess, and Winnie: The Opera (Bongani Ndodana-Breen). A chapter is devoted to the nineteenth-century Carmens (novella by Mérimée and opera by Bizet) and black settings in the United States (Carmen Jones, Carmen: A Hip Hopera) and South Africa (U-Carmen eKhayelitsha). Woven within the discussions of specific works are three rubrics for how the text and music create the drama: Who is in the story? Who speaks? and Who is in the audience doing the interpreting? These questions, combined with a historical context that includes how a work also resonates in the present day, form the basis for an engaged musicological practice.

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Capítulos de livros sobre o assunto "Carbon segregation"

Vlasov, N. M., e I. I. Fedik. "Hydrogen Segregation in the Residual Stresses Field". In Hydrogen Materials Science and Chemistry of Carbon Nanomaterials, 357–62. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/1-4020-2669-2_40.

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Giannazzo, F., C. Bongiorno, S. di Franco, R. Lo Nigro, E. Rimini e V. Raineri. "Morphological and Structural Characterization of Graphene Grown by Thermal Decomposition of 4H-SiC (0001) and by C Segregation on Ni". In Carbon Nanostructures, 99–107. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-20644-3_12.

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Takaki, Setsuo, Nobuo Nakada e Toshihiro Tsuchiyama. "Grain Boundary Carbon Segregation Estimated by McLean and Seah-Hondros Models". In Advanced Steels, 81–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17665-4_10.

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Hendy, Mohamed, Tarek M. Hatem e Jaafar A. El-Awady. "Atomistic Simulations of Carbon Diffusion and Segregation in α-Iron Grain Boundaries". In TMS 2018 147th Annual Meeting & Exhibition Supplemental Proceedings, 323–32. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-72526-0_30.

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Yang, Yuhou, Bo Song, Gaoyang Song e Zeyun Cai. "Effect of Super Gravity on the Solidification Structure and C Segregation of High-Carbon Steel". In The Minerals, Metals & Materials Series, 571–79. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-51340-9_56.

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Ji, Yuan, Yujun Li, Shaoxiang Li, Xiaofeng Zhang e Jiaquan Zhang. "Central Segregation of High-carbon Steel Billet and Its Heredity to the Hotrolled Wire Rods". In 7th International Symposium on High-Temperature Metallurgical Processing, 625–33. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119274643.ch77.

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Ji, Yuan, Yujun Li, Shaoxiang Li, Xiaofeng Zhang e Jiaquan Zhang. "Central Segregation of High-carbon Steel Billet and Its Heredity to the Hot-rolled Wire Rods". In 7th International Symposium on High-Temperature Metallurgical Processing, 625–33. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48093-0_77.

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Zhong, Honggang, Yi Tan, Huigai Li, Xinping Mao e Qijie Zhai. "The Effect of High Superheat on the Solidification Structure and Carbon Segregation of Ferrite-Based Alloy". In Supplemental Proceedings, 215–21. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118356074.ch29.

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Xu, Xiaohong, Jigang Liu, Guoqing Xu, Qing Yin, Xudong Zhang e Hans-Åke Munther. "Improvements in GCr15 (52100) High Carbon Bearing Steel Steelmaking and Their Effect on Inclusions, Segregation, and Fatigue Properties". In Bearing Steel Technologies: 12th Volume, Progress in Bearing Steel Metallurgical Testing and Quality Assurance, 381–402. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2020. http://dx.doi.org/10.1520/stp162320190060.

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Sinha, Avik, Oana M. Driha, Daniel Balsalobre-Lorente e José María Cantos-Cantos. "Impact of Energy Use Segregation on Carbon Emissions: The Role of FDI in Net Importing and Net Exporting Countries". In Econometrics of Green Energy Handbook, 1–30. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-46847-7_1.

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Trabalhos de conferências sobre o assunto "Carbon segregation"

Teixeira, J., M. Salazar, J. Macchi, S. Gaudez, G. Geandier, S. Allain, S. Denis e F. Danoix. "Effects of Carbon and Nitrogen Concentrations on Precipitation Sequence during Tempering of Martensitic Steels Investigated by Advanced Experimental Methods and Modeling". In IFHTSE 2024, 327–31. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.ifhtse2024p0327.

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Abstract Advanced characterization techniques and modeling are used to get new insight on the microstructural evolutions occurring during the tempering of low-alloyed steels with initial martensitic microstructure. Tempering temperatures from 150°C to 600°C, are considered to make vary the metallurgical phenomena activated, form carbon segregation to defects to precipitation of different types of carbides (transition, cementite, alloyed). A large range of carbon compositions, from 0.1 to 0.7 wt.% are investigated, with the same main experimental technique: in situ HEXRD at synchrotron beamlines, with complementary post mortem fine-scale characterizations by TEM and 3D-APT. In the middle of this range (~0.3wt.%), the usual sequence is observed: successive precipitation of transition and cementite carbides. New observations concern the carbon concentrations outside this range. For high carbon concentrations (~0.6wt.%), the same sequence occurs but the martensite/ferrite matrix remains highly supersaturated in carbon compared to equilibrium, for a long time and even after the precipitation of cementite. For low carbon concentrations (~0.1wt.%) most of the carbon starts to segregate at defects (dislocations, lath boundaries). This enters in competition with the transition carbides which are almost fully hindered, whereas cementite precipitates afterwards. Two previous models from literature are combined to predict the concomitant kinetics of carbon segregation and precipitation. Segregation puts the transition carbides at a disadvantage with cementite and for this reason, the latter precipitates earlier than usually reported. The effects of nitrogen enrichment (up to ~0.4 wt.%N, context of carbonitriding thermochemical treatments) in austenite domain of stability (before the martensitic quench) are also investigated. In low-alloyed steel considered (23MnCrMo5), nitrides are formed upon enrichment (CrN, MnSiN2). This has a strong impact on the precipitation sequence, compared to model systems previously investigated (Fe-N, Fe-C-N).

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Fichot, Philippe, Olivier Calonne, Mathieu Segond, Stéphane Marie, Yvon Desnoyers, Mejido Hajjaj e Cecile Miller. "Flamanville EPR RPV’s Heads Carbon Segregation: Characterization of the Segregation in the Heads". In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84495.

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To characterize the mechanical properties of the residual carbon segregation of the Flamanville EPR RPV heads, a testing program has been defined by Framatome using three sacrificial representative heads. The first step of this program was a 3D characterization of the carbon content inside each piece. A specific strategy has been defined using two methods for the carbon measuring: - In situ measurements using a mobile arc spark spectrometer. This device allows a higher number of non-destructive measurements in a particularly constrained environment and in a short time, - Conventional spectrometry performed on chips sampled from the pieces. This technique is more accurate but is destructive and more time consuming. Also, to consolidate the representativeness of the sacrificial vessels heads, the results were analysed using a geostatistical approach. This paper presents how these two techniques have been used to characterize the carbon content in the segregated part of the pieces and the conclusion of the geostatistical analyses.

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Marie, Stéphane, Jérôme Demarecaux, Philippe Fichot, Elisabeth Keim, Johannes May, Marlies Lambrecht, Rachid Chaouadi, Peter Birkett, Mejido Hajjaj e Cecile Miller. "Flamanville EPR RPV’s Heads Carbon Segregation: Tests Program Definition to Characterize the Mechanical Properties of the Carbon Segregation". In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84329.

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To characterize the mechanical properties of the residual carbon segregation of the Flamanville EPR RPV heads, a testing program have been organized by Framatome and performed in 3 laboratories (Wood, Framatome technical center of Erlangen and SCK Mol). This paper presents the tests program, how it has been defined and its goals. The main issue was the impact of the carbon content on the toughness properties. A procedure was defined to characterize specifically the toughness distribution in the upper part of the brittle-to-ductile transition. The ductile regime was also investigated. These tests were completed with tensile, Charpy and drop weight tests, representing a final total of approximatively 1700 mechanical tests.

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Marie, Stéphane, Jérôme Demarecaux, Philippe Fichot, Mejido Hajjaj e Cecile Miller. "Flamanville EPR RPV’s Heads Carbon Segregation: Impact of the High Carbon Segregation on the Mechanical Properties of the RPV Steel". In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84330.

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To characterize the mechanical properties of the residual carbon segregation of the Flamanville EPR RPV heads, a testing program have been organized by Framatome and performed in 3 laboratories. Three sacrificial pieces have been used for this program, allowing the investigation of different carbon contents, coupled with different quenching conditions (thanks to a specimen sampling at different positions in the heads thickness). As expected, the increase of the carbon content leads to an increase of the tensile properties, a shift toward the higher temperature of the brittle-to-ductile transition and a lowering of the toughness in the ductile regime. In the worst case, compare to the RTNDT measured in the frame of acceptance tests of the heads, the temperature to be considered to envelop all the experimental results with the toughness curve of the RCC-M code is 20°C higher. The extensive test program allows a quantification of these impacts for the integrity assessments of the RPV. It is also demonstrated that the segregated material remains homogeneous, with a classical failure mode by cleavage. Master Curve approach is also applicable and used to characterize the carbon content impact on the toughness properties.

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Hernández, Luis, Hector Carreón e Arnoldo Jacuinde. "Detection of Segregation in a High Carbon Steel by Non-Destructive Techniques". In 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/qnde2021-75006.

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Abstract In high carbon steel manufacture, segregation is a common problem that compromises the quality and performance of cast products. When they are rolled or forged, hard metallurgical phases can develop, promoting material embrittlement. To detect the segregation presence, traditionally, it is analyzed by macro-attack (according to the ASTM 381 standard). However, this methodology is limited to the subjective interpretation of the quality inspector, and also it is dangerous. Non-destructive means represent an agile alternative for quality control because they are sensitive to the chemical composition and microstructure of the steel. Through conventional ultrasound technique, an increase in attenuation coefficient was detected in the area of greater segregation and lower values in regions with greater chemical homogeneity. On the other hand, the longitudinal wave velocity was lower in the segregated region and higher in the zone with less segregation. Furthermore, by some mathematical relationships and wave speeds, Poisson’s ratio Young’s and shear modulus were obtained, which are related to the ease of rolling in steel. Finally, Eddy currents and impedance plane determined that the segregation region has a lower phase angle, and therefore, a higher electrical conductivity concerning the zones of less segregation.

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Lefever, Benoit, Stéphane Marie, Thierry Berger e Isabelle Bobin Vastra. "Flamanville EPR RPV’s Heads Carbon Segregation: Vessel Heads Manufacturing". In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84492.

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The FA3 RPV heads segregation has been an important issue for the Flamanville 3 EPR project. A high carbon content of carbon has been measured at the outer central part of the two heads. Manufactured in 2006 according to the RCC-M requirements, these pieces were also submitted to the ESPN (i.e. nuclear pressurized equipment) French order requirements, and in particular the ESPN technical qualification. This paper presents the manufacturing of these heads to explain the origin of the segregation and place this process in its context, with in particular a clarification of the technical qualification requirements in 2011, which are different to the RCC-M qualification process. This qualification required additional chemical and mechanical characterizations in the segregated area of the representative vessel head. The additional Charpy-V test did not meet the 60 J requirement of the ESPN order and led to the large testing program to characterize the toughness properties of the segregated material.

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Gamble, Ronald, e Timothy Hardin. "Evaluation of Risk From Carbon Macro-Segregation in Large Pressure Retaining Forged Nuclear Components". In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84620.

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Regions of higher-than-normal carbon content due to carbon macro-segregation have been found in large, pressure retaining forged ferritic steel components in some nuclear reactors. Higher carbon content in ferritic steel can decrease the resistance to fracture from the presence of flaws in the material. Acceptable margins against failure of pressurized components in nuclear safety systems must be maintained throughout their service life to ensure core integrity for all operational and postulated transient loading events. Should carbon macro-segregation substantially reduce the material resistance to fracture in safety components, then the margins against through-wall flaw propagation may fall below those specified by regulatory requirements to ensure adequate component and reactor core integrity. Probabilistic fracture mechanics (PFM) analyses were performed to assess the risk and structural significance of postulated carbon macro-segregation in large, forged pressure retaining components in pressurized water reactors (PWRs). The risk assessment was performed to evaluate several forged components and two classes of loading events. The forged components include the ring and head forgings in the reactor pressure vessel (RPV), steam generator (S/G) and pressurizer. The loading events used in the risk evaluation include pressurized thermal shock (PTS) transient events and a normal RPV cooldown event. The analyses included a range of component dimensions, surface and embedded flaw distributions, various levels of carbon macro-segregation up to and beyond the maximum measured values for the components, and the effects of neutron irradiation, including the effects of potential copper and phosphorus co-segregation. The PFM analyses were performed using the software, Fracture Analysis of Vessels, Oak Ridge (FAVOR). The results from the risk assessment indicate that: acceptable margins against failure are maintained through an 80-year operating interval even if carbon macro-segregation were to be present in RPV, S/G and pressurizer ring and head forgings in PWRs; and the risk associated with the presence of carbon macro-segregation in PWR ring and head forgings is significantly lower than regulatory risk related acceptance criteria.

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Dybdahl, Cato, Nora Dahle e Stanka Tomovic-Petrovic. "An Approach to Micro Segregation Level and Presence of Quench Cracks in Medium Carbon Low Alloy Steels". In HT2019. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.ht2019p0316.

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Abstract Samples from forged and heat-treated steel products with known quench crack histories have been mapped in order to study a possible relation between banding segregation and quench cracking. The steels were medium carbon low alloy steels, ingot and continuous cast, as well as vacuum arc remelt D6AC. EDS X-ray mapping was applied to characterize the banding segregation pattern from casting i.e. gradient of chemical composition that creates direction dependent properties. Trends for segregation ratios followed the expectations: the segregation ratios were higher for the quench sensitive steels.34CrNiMo6, ingot- and continuous cast, was then supplied for testing. Segregation level was pre-checked for decision for heat treatment and testing of as quenched tensile properties. There is an indication of 90 % reduction of the difference between Rm and Rp0.2, the work hardening, for the steel with lowest quality.

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Hayashi, Takahiro, Takuya Ogawa, Rie Sumiya, Tetsushi Yamaoka, Shigeaki Tanaka, Yasuhiro Hattori e Atsushi Mori. "Investigation on the Effects of Carbon Macro-Segregation of Mechanical Properties Using a Large-Scale Forged Low Alloy Steel for a BWR Reactor Pressure Vessel". In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21857.

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Abstract Control of carbon macro-segregation in the steel-making process for large steel forgings is of great importance in order to achieve the material properties and structural reliability required for the pressure vessels of nuclear power plant components. It is well known that high carbon content due to carbon macro-segregation can affect the mechanical properties of steels, leading to decreases in ductility and fracture toughness. In this study, possible effects of carbon macro-segregation have been examined using a large-scale forged steel “bottom head dome” of a reactor pressure vessel (RPV) manufactured for a recent BWR. Material testing conducted included chemical analyses, tensile tests and Charpy impact tests. In the center part of the concave disk-shaped forged material, carbon content varied slightly in the material thickness direction within the range of carbon content requirement, as expected from the relationship between the solidification and the resultant segregation process in the cast ingot material and the forging process from the ingot to the dome material. The results of each mechanical test also showed full compliance with the properties required in the code regardless of the carbon content at each of the thickness locations examined. All the tests results demonstrated that with the steel-making technology and practice employed, carbon macro-segregation is well controlled to achieve the required material properties even in large-scale forged materials used in BWRs.

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Lefrançois, André, Thierry Berger, Benoît Lefever e Stéphane Marie. "FA3 RPV Carbon Segregation Issue: Representativeness and Transferability of Sacrificial Parts". In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84487.

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In order to demonstrate that the cover head and bottom head of the FA3 Reactor Pressure Vessel (RPV) exhibits sufficient toughness to withstand operational (from normal up to faulted) conditions, a dedicated experimental program was performed for three sacrificial forged parts (two cover heads and a bottom head) manufactured in Creusot Forge as-well, according to a similar process. In order to be allowed to consider the mechanical properties (toughness) measured on these sacrificial parts, it was necessary to prove that they were representative of the FA3 ones. Among all the parameters influencing the toughness properties it was defined that two of them had a major impact: the carbon content and the quenching effects. For the first one, it was identified that it could be influenced by pouring conditions, forging conditions, including discard and upsetting ratios and machining (thickness). For the second one, it was identified that it could be influenced by post-heat treatment machining and by quenching conditions. Regarding these factors, for the five parts: manufacturing parameters and acceptance test results were compared, taking into account uncertainties. In addition, for the three sacrificial parts, carbon content measured for various depths in the thickness were compared, after a transformation methodology allowing to convert depth inside part to ingot vertical location. Finally, it was shown that the sacrificial parts could be considered to be representative of the FA3 parts to be used, for their mechanical properties.

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Relatórios de organizações sobre o assunto "Carbon segregation"

Martinez Saez, Enrique. The Kinetic Monte Carlo Algorithm in Materials Science: Study of Radiation-Induced Segregation in Fe-Cr alloys. Office of Scientific and Technical Information (OSTI), setembro de 2018. http://dx.doi.org/10.2172/1475306.

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Bennett, Alan B., Arthur A. Schaffer, Ilan Levin, Marina Petreikov e Adi Doron-Faigenboim. Manipulating fruit chloroplasts as a strategy to improve fruit quality. United States Department of Agriculture, janeiro de 2013. http://dx.doi.org/10.32747/2013.7598148.bard.

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The Original Objectives were modified and two were eliminated to reflect the experimental results: Objective 1 - Identify additional genetic variability in SlGLK2 and IPin wild, traditional and heirloom tomato varieties Objective 2 - Determine carbon balance and horticultural characteristics of isogenic lines expressing functional and non-functional alleles of GLKsand IP Background: The goal of the research was to understand the unique aspects of chloroplasts and photosynthesis in green fruit and the consequences of increasing the chloroplast capacity of green fruit for ripe fruit sugars, yield, flavor and nutrient qualities. By focusing on the regulation of chloroplast formation and development solely in fruit, our integrated knowledge of photosynthetic structures/organs could be broadened and the results of the work could impact the design of manipulations to optimize quality outputs for the agricultural fruit with enhanced sugars, nutrients and flavors. The project was based on the hypothesis that photosynthetic and non-photosynthetic plastid metabolism in green tomato fruit is controlled at a basal level by light for minimal energy requirements but fruit-specific genes regulate further development of robust chloroplasts in this organ. Our BARD project goals were to characterize and quantitate the photosynthesis and chloroplast derived products impacted by expression of a tomato Golden 2- like 2 transcription factor (US activities) in a diverse set of 31 heirloom tomato lines and examine the role of another potential regulator, the product of the Intense Pigment gene (IP activities). Using tomato Golden 2-like 2 and Intense Pigment, which was an undefined locus that leads to enhanced chloroplast development in green fruit, we sought to determine the benefits and costs of extensive chloroplast development in fruit prior to ripening. Major conclusions, solutions, achievements: Single nucleotide polymorphisms in the promoter, coding and intronicSlGLK2 sequences of 20 heirloom tomato lines were identified and three SlGLK2 promoter lineages were identified; two lineages also had striped fruit variants. Lines with striped fruit but no shoulders were not identified. Green fruit chlorophyll and ripe fruit soluble sugar levels were measured in 31 heirloom varieties and fruit size correlates with ripe fruit sugars but dark shoulders does not. A combination of fine mapping, recombinant generation, RNAseq expression and SNP calling all indicated that the proposed localization of a single locus IP on chr 10 was incorrect. Rather, the IP line harbored 11 separate introgressions from the S. chmielewskiparent, scattered throughout the genome. These introgressions harbored ~3% of the wild species genome and no recombinant consistently recovered the IP parental phenotype. The 11 introgressions were dissected into small combinations in segregating recombinant populations. Based on these analyses two QTL for Brix content were identified, accounting for the effect of increased Brix in the IP line. Scientific and agricultural implications: SlGLK2 sequence variation in heirloom tomato varieties has been identified and can be used to breed for differences in SlGLK2 expression and possibly in the green striped fruit phenotype. Two QTL for Brix content have been identified in the S. chmielewskiparental line and these can be used for increasing soluble solids contents in breeding programs.

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