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Search Results: 1 - 10 of 120558 matches for " Gema T; Bueno Tokunaga "
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Estudio de la recristalización secundaria en un acero de bajo carbono laminado a alta temperatura
Ramos Escobedo,Gema T; Bueno Tokunaga,Arturo; Rendón García,Nallely M;
Revista Latinoamericana de Metalurgia y Materiales , 2007,
Abstract: durante la inspección de rutina de la microestructura de una lámina de acero de bajo carbono de 1,9 mm de espesor, producida por laminación continua a alta temperatura de un planchón delgado de 50 mm de espesor fabricado por colada continua, se encontró evidencia de la formación de bandas longitudinales superficiales de granos de ferrita anormalmente grandes. el análisis del comportamiento de disolución de fe3c y de la recristalización de la fase a-fe durante tratamientos de recocido permitió descubrir una fuerte decarburización superficial de la lámina. en base a la anterior observación, la presencia de esta inusual microestructura fue atribuida a la deformación, recristalización y crecimiento anormal de grano de la fase a-fe deformada a alta temperatura durante la laminación en caliente y al enfriamiento lento asociado con las altas temperaturas de acabado y enrollado de la cinta de acero. la existencia de bandas superficiales con granos finos y grandes se atribuyó a que la decarburización no fue uniforme en la superficie del planchón o la lámina. en regiones no decarburizadas, la recristalización normal de la austenita entre los pasos de laminación resultó en una microestructura de granos finos de a-fe una vez que se realizó la transformación de fase en el material.
Estudio de la recristalización secundaria en un acero de bajo carbono laminado a alta temperatura During the routine inspection of the microstructure of a low carbon steel sheet 1.9 mm of thickness, produced by high temperature rolling of a continuous casting slab, 50 mm thickness, the formation of superficial coarse ferrite grains was observed. A strong decarburization on the surface of the steel
Gema T Ramos Escobedo,Arturo Bueno Tokunaga,Nallely M Rendón García
Revista Latinoamericana de Metalurgia y Materiales , 2007,
Abstract: Durante la inspección de rutina de la microestructura de una lámina de acero de bajo carbono de 1,9 mm de espesor, producida por laminación continua a alta temperatura de un planchón delgado de 50 mm de espesor fabricado por colada continua, se encontró evidencia de la formación de bandas longitudinales superficiales de granos de ferrita anormalmente grandes. El análisis del comportamiento de disolución de Fe3C y de la recristalización de la fase a-Fe durante tratamientos de recocido permitió descubrir una fuerte decarburización superficial de la lámina. En base a la anterior observación, la presencia de esta inusual microestructura fue atribuida a la deformación, recristalización y crecimiento anormal de grano de la fase a-Fe deformada a alta temperatura durante la laminación en caliente y al enfriamiento lento asociado con las altas temperaturas de acabado y enrollado de la cinta de acero. La existencia de bandas superficiales con granos finos y grandes se atribuyó a que la decarburización no fue uniforme en la superficie del planchón o la lámina. En regiones no decarburizadas, la recristalización normal de la austenita entre los pasos de laminación resultó en una microestructura de granos finos de a-Fe una vez que se realizó la transformación de fase en el material.
PAI-1 and functional blockade of SNAI1 in breast cancer cell migration
Elizabeth Fabre-Guillevin, Michel Malo, Amandine Cartier-Michaud, Hector Peinado, Gema Moreno-Bueno, Beno?t Vallée, Daniel A Lawrence, José Palacios, Amparo Cano, Georgia Barlovatz-Meimon, Cécile Charrière-Bertrand
Breast Cancer Research , 2008, DOI: 10.1186/bcr2203
Abstract: We compared the invasive breast cancer cell-line MDA-MB-231 expressing SNAI1 (MDA-mock) with its derived clone expressing a dominant-negative form of SNAI1 (SNAI1-DN). Expression of PA system mRNAs was analysed by cDNA microarrays and real-time quantitative RT-PCR. Wound healing assays were used to determine cell migration. PAI-1 distribution was assessed by immunostaining.We demonstrated by both cDNA microarrays and real-time quantitative RT-PCR that the functional blockade of SNAI1 induces a significant decrease of PAI-1 and uPA transcripts. After performing an in vitro wound-healing assay, we observed that SNAI1-DN cells migrate more slowly than MDA-mock cells and in a more collective manner. The blockade of SNAI1 activity resulted in the redistribution of PAI-1 in SNAI1-DN cells decorating large lamellipodia, which are commonly found structures in these cells.In the absence of functional SNAI1, the expression of PAI-1 transcripts is decreased, although the protein is redistributed at the leading edge of migrating cells in a manner comparable with that seen in normal epithelial cells.Epithelial-mesenchymal transition (EMT) is a process whereby epithelial cell layers lose polarity and cell-cell contacts and undergo a dramatic remodelling of the cytoskeleton. EMT is characterised by a loss of intercellular adhesion, down-regulation of epithelial markers, up-regulation of mesenchymal markers, and acquisition of a spindle-shape and single-cell migration [1,2]. Many of the molecular changes occurring during developmental EMT are also characteristics of most aggressive metastatic cancer cells [2-5].Important in EMT is the Snail family of transcriptional repressors whose members including SNAI1, also known as snail, and SNAI2, also known as slug [6]. One of the major effects of Snail family molecules is the induction of a mesenchymal and invasive phenotype [7]. This process includes alterations in the expression of a wide number of proteins involved in cell-to-cell and
Discovery of Crystallized Water Ice in a Silhouette Disk in the M43 Region
Hiroshi Terada,Alan T. Tokunaga
Physics , 2012, DOI: 10.1088/0004-637X/753/1/19
Abstract: We present the 1.9--4.2um spectra of the five bright (L<11.2) young stars associated with silhouette disks with moderate to high inclination angle of 39--80deg in the M42 and M43 regions. The water ice absorption is seen toward d121-1925 and d216-0939, while the spectra of d182-316, d183-405, and d218-354 show no water ice feature around 3.1um within the detection limits. By comparing the water ice features toward nearby stars, we find that the water ice absorption toward d121-1925 and d216-0939 most likely originates from the foreground material and the surrounding disk, respectively. The angle of the disk inclination is found to be mainly responsible for the difference of the optical depth of the water ice among the five young stars. Our results suggest that there is a critical inclination angle between 65deg and 75deg for the circumstellar disk where the water ice absorption becomes strong. The average density at the disk surface of d216-0939 was found to be 6.38x10^(-18) g cm^(-3). The water ice absorption band in the d216-0939 disk is remarkable in that the maximum optical depth of the water ice band is at a longer wavelength than detected before. It indicates that the primary carrier of the feature is purely crystallized water ice at the surface of the d216-0939 disk with characteristic size of ~0.8um, which suggests grain growth. This is the first direct detection of purely crystallized water ice in a silhouette disk.
Discovery of Young Stellar Objects at the Edge of the Optical Disk of Our Galaxy
Naoto Kobayashi,Alan T. Tokunaga
Physics , 1999, DOI: 10.1086/308564
Abstract: We report a discovery of young stellar objects associated with a molecular cloud at the edge of the optical disk of our Galaxy. This cloud is denoted as Cloud 2 in the list by Digel et al. and it is one of the most distant molecular clouds from the Galactic center known to date, with a probable distance of 15-19 kpc. We found seven red near-infrared sources associated with this cloud. Based on our near-infrared observations and far-infrared/radio data in the literature, we conclude that most sources are likely to be members of Cloud 2. The geometry of ionized gas, IRAS sources, near-infrared sources, and molecular cloud suggests that MR-1, an isolated early B-type star near Cloud 2, has triggered the star formation activity in Cloud 2. Our results show that ongoing star formation is present in Cloud 2 and that active star formation can occur in the farthest regions of the Galaxy, where the molecular gas density is extremely low, perturbation from the spiral arms is very small, and the metallicity is similar to that for irregular dwarf galaxies. Cloud 2 is an excellent laboratory in which to study the details of the star formation process in an environment that is similar to that in the early stage of the formation of the Galactic disk.
K-Band Spectra and Narrowband Photometry of DENIS Field Brown Dwarfs
A. T. Tokunaga,N. Kobayashi
Physics , 1998, DOI: 10.1086/300732
Abstract: Infrared spectra at 1.9-2.5 micron and narrowband photometry of three low-mass objects, DENIS-P J0205.4-1159, J1058.7-1547, and J1228.2-1547, are presented. As shown previously by Delfosse et al. (1997, AA, 327, L25), DENIS-P J0205.4-1159 shows an absorption feature at 2.2 microns. We attribute this absorption to H_2. A simple two-parameter analysis of the K-band spectrum of low-mass objects is presented in which the relative strength of the H_2O and H_2 absorption bands is found to be correlated with the effective temperature of the objects. The analysis confirms that DENIS-P J0205.4-1159 is the lowest-temperature object of the three. We present narrow-band photometry of these objects which provides the continuum flux level inbetween the deep H_2O absorption bands. These data show the continuum level accurately for the first time, and they will provide tight constraints for spectral models of these interesting objects.
Current oscillation and low-field colossal magnetoresistance effect in phase-separated manganites
M. Tokunaga,H. Song,Y. Tokunaga,T. Tamegai
Physics , 2005, DOI: 10.1103/PhysRevLett.94.157203
Abstract: Current-induced switching from metallic to insulating state is observed in phase-separated states of (La_{1-y}Pr_y)_{0.7}Ca_{0.3}MnO_3 (y=0.7) and Nd_{0.5}Ca_{0.5}Mn_{1-z}Cr_zO_3 (z=0.03) crystals. Application of magnetic fields to this current-induced insulating state causes pronounced low-field negative magnetoresistance effect [r(H)/r(0)=10^{-3} at H=1kOe]. Application of a constant voltage also causes breakdown of ohmic relation above a threshold voltage. At voltages higher than this threshold value, oscillations in currents are observed. This oscillation is well reproduced by a simple model of local switching of a percolative conduction path.
Multivalued memory effects in electronic phase-change manganites controlled by Joule heating
H. Song,M. Tokunaga,S. Imamori,Y. Tokunaga,T. Tamegai
Physics , 2006, DOI: 10.1103/PhysRevB.74.052404
Abstract: Non-volatile multivalued memory effects caused by magnetic fields, currents, and voltage pulses are studied in Nd_{0.65}Ca_{0.35}MnO_3 and (Nd_{1-y}Sm_{y})_{0.5}Sr_{0.5}MnO_3 (y=0.75) single crystals in the hysteretic region between ferromagnetic metallic and charge-ordered insulating states. The current/voltage effects observed in this study are explained by the self-heating effect, which enable us to control the colossal electroresistance effects. This thermal-cycle induced switching between electronic solid and liquid states can be regarded as electronic version of atomic crystal/amorphous transitions in phase-change chalcogenides.
Estrategias para el éxito de los repositorios institucionales de contenido educativo en las bibliotecas digitales universitarias
Bueno de la Fuente, Gema,Hernández Pérez, Tony
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2011, DOI: 10.1344/105.000001727
Abstract: Objetivos. Identificar y proponer estrategias para el éxito en la creación de repositorios de contenidos digitales educativos (objetos de aprendizaje y otros materiales didácticos y de apoyo a la docencia) en las universidades, adaptándose a sus especiales características y necesidades en cuanto a la gestión, preservación y ciclo de vida, que los distinguen de los materiales de investigación y exigen un enfoque diferenciado. -- Metodología. Análisis de las principales barreras y retos que se han identificado para la implementación y adopción de repositorios de contenidos educativos en la bibliografía especializada y en los experiencias previas a nivel internacional. Selección de las barreras más comunes e identificación de las estrategias implantadas con buenos resultados en otros repositorios. -- Resultados. Se han seleccionado y propuesto un conjunto de nueve estrategias de éxito, que hacen especial hincapié en las barreras socio-culturales asociadas al intercambio y la reutilización de materiales educativos, pues son las más comunes y difíciles de afrontar. Se entiende por éxito que los repositorios sean adoptados por sus usuarios potenciales: docentes, alumnos y autores de contenido educativo, contribuyendo y reutilizando materiales, y repercutiendo en la mejora de la ense anza y el aprendizaje. En la mayor parte de las universidades espa olas, la atención dedicada a los contenidos educativos en los repositorios institucionales es aún insuficiente o no se adecua a sus especiales características y hábitos de producción y uso. Es necesario un cambio de perspectiva donde las bibliotecas universitarias deben tomar un papel activo de concienciación y promoción de la importancia de este acervo intelectual en formato digital.Objectives. To propose strategies for successful storage of digital educational materials for use at universities. These strategies must be adapted to the characteristics and needs of these materials with regard to their management and preservation and also with regard to their lifespan. These features distinguish teaching materials from research materials and call for a different approach to their management. -- Methodology. An analysis of the main barriers and challenges for the implementation and adoption of storage systems for educational materials, based on the specialist bibliography and on prior experiences at international level. The most common barriers and the strategies successfully implemented in other storage systems are discussed. -- Results. We propose a set of successful new strategies that place special emphasis on ove
Estratègies per a l'èxit dels dipòsits institucionals de contingut educatiu en les biblioteques digitals universitàries
Bueno de la Fuente, Gema,Hernández Pérez, Tony
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2011, DOI: 10.1344/105.000001726
Abstract: Objectius. Identificar i proposar estratègies per a l'èxit en la creació de dipòsits de continguts digitals educatius (objectes d'aprenentatge i d'altres materials didàctics i de suport a la docència) a les universitats, adaptant-se a les seves característiques especials i necessitats quant a la gestió, preservació i cicle de vida, que els distingeixen dels materials de recerca i exigeixen un enfocament diferenciat. -- Metodologia. Anàlisi de les principals barreres i reptes que s'han identificat per a la implementació i adopció de dipòsits de continguts educatius en la bibliografia especialitzada i en els experiències prèvies a nivell internacional. Selecció de les barreres més comunes i identificació de les estratègies implantades en altres dipòsits i amb bons resultats. -- Resultats. S'han seleccionat i proposat un conjunt de nou estratègies d'èxit, que fan èmfasi especial en les barreres socioculturals associades a l'intercanvi i la reutilització de materials educatius, ja que són les més comunes i difícils d'afrontar. S'entén per èxit que els dipòsits siguin adoptats pels seus usuaris potencials: docents, alumnes i autors de contingut educatiu, contribuint i reutilitzant materials, i repercutint en la millora de l'ensenyament i l'aprenentatge. En la major part de les universitats espanyoles, l'atenció dedicada als continguts educatius en els dipòsits institucionals és encara insuficient o no s'adequa a les seves característiques especials i hàbits de producció i ús. Cal un canvi de perspectiva on les biblioteques universitàries han de prendre un paper actiu de conscienciació i promoció de la importància d'aquest patrimoni intel·lectual en format digital.Objectives. To propose strategies for successful storage of digital educational materials for use at universities. These strategies must be adapted to the characteristics and needs of these materials with regard to their management and preservation and also with regard to their lifespan. These features distinguish teaching materials from research materials and call for a different approach to their management. -- Methodology. An analysis of the main barriers and challenges for the implementation and adoption of storage systems for educational materials, based on the specialist bibliography and on prior experiences at international level. The most common barriers and the strategies successfully implemented in other storage systems are discussed. -- Results. We propose a set of successful new strategies that place special emphasis on overcoming the sociocultural barriers associated with the interchang
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