933,376 research outputs found
Lentejas: si quieres las comes, y si no también
Full text link2016 fue proclamado por primera vez Año Internacional de las Legumbres por la Asamblea General de las Naciones Unidas. Desde entonces, cada 10 de febrero se conmemora el Día Mundial de este alimento, que en 2021 tiene como lema “#AmaLasLegumbres por una dieta y un planeta sanos”. Pero, ¿qué tienen las legumbres para merecer tanto protagonismo?, ¿qué explica la evolución desde el dicho “las legumbres dan muchas pesadumbres” a la frase “lentejas: si quieres las comes y si no, también”
New approaches to casting hypereutectic Al-Si alloys to achieve simultaneous refinement of primary silicon and modification of eutectic silicon
Full text linkThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityHypereutectic Al-Si alloys are of increasing interest for applications that require a combination of light weight and high wear resistance, such as pistons, liner-less engine blocks and pumps. The wear resistance of this class of alloys is due to the presence of hard primary Si particles formed during casting. The objective of this work was to develop one or more methods of refining primary silicon in cast hypereutectic Al-Si alloys to compete with the conventional process of adding phosphorous and to achieve the simultaneous modification of silicon in the Al-Si eutectic. A robust sampling/casting technique was developed to minimise macro-segregation of primary silicon during solidification of hypereutectic Al-Si alloys by using water cooled steel mould with cooling rate in excess of 15 K/s. The morphology of silicon phases was found to change with increasing melt temperature and cooling rate. The high cooling rate and superheat temperature produces a good distribution of polyhedral primary silicon particles in a refined lamellar eutectic matrix in solidification of commercial purity Al-Si alloys. Removing Ca by fluxing with K2SiF6 prior to casting can improve the refinement and modification effect of Mg and Sb respectively. Effects of various inoculants were studied. Microstructural analysis showed that Mg and ZnS refined primary Si whereas MgO, CaO and Na2S coarsened the primary Si together with a modification effect on the eutectic Si. Adding Zn had no effect on morphology of Si phases. Refinement of both primary and eutectic silicon phases was observed for the Al-15Si alloy with Mg content ≤ 0.3 wt%.
P-doped γ-Al2O3 was found to be a potent substrate to nucleate primary silicon whilst good modification of the eutectic matrix is retained during solidification of hypereutectic Al-Si alloys. On using P-doped γ-Al2O3 could be a perfect and clean source of P without additional impurities.
A new solid-liquid duplex casting process was devised to achieve simultaneous refinement and modification of Si phases in hypereutectic Al-Si alloys with improvement in mechanical properties. The static mechanical properties of Al-Si produced by the solid-liquid duplex casting process are significantly better than conventionally cast untreated Al-Si and slightly better than conventionally cast Al-Si treated with P and/or Sr. A novel Al-ZnS master alloy was developed by in situ reaction of Zn and Na2S in the Al melt. The results from this study leave little doubt that this novel Al-ZnS master alloy is a promising refiner in solidification of hypereutectic Al-Si alloys. It refines primary silicon to the same extent as that achieved by adding P via Cu-P following the same refinement mechanism.EPSRC,U
Recent progress on synthesis, multi-scale structure, and properties of Y-Si-O oxides
No full textYttrium silicates (Y-Si-O oxides), including Y2Si2O7, Y2SiO5, and Y4·67(SiO4)3O apatite, have attracted wide attentions from material scientists and engineers, because of their extensive polymorphisms and important roles as grain boundary phases in improving the high-temperature mechanical/thermal properties of Si3N4 and SiC ceramics. Recent interest in these materials has been renewed by their potential applications as high-temperature structural ceramics, oxidation protective coatings, and environmental barrier coatings (EBCs). The salient properties of Y-Si-O oxides are strongly related to their unique chemical bonds and microstructure features. An in-depth understanding on the synthesis - multi-scale structure-property relationships of the Y-Si-O oxides will shine a light on their performance and potential applications. In this review, recent progress of the synthesis, multi-scale structures, and properties of the Y-Si-O oxides are summarised. First, various methods for the synthesis of Y-Si-O ceramics in the forms of powders, bulks, and thin films/coatings are reviewed. Then, the crystal structures, chemical bonds, and atomic microstructures of the polymorphs in the Y-Si-O system are summarised. The third section focuses on the properties of Y-Si-O oxides, involving the mechanical, thermal, dielectric, and tribological properties, their environmental stability, and their structure-property relationships. The outlook for potential applications of Y-Si-O oxides is also highlighted
Restitución y derecho a la tierra
No full textEste boletín hace parte de la serie "¿Y si la tierra hablara? Ecos de la restitución" y da cuenta de temáticas específicas, las cuales atañen a los procesos de restitución de tierras, así como de elementos importantes encontrados en las visitas a terreno en municipios en los que la política de restitución de tierras se ha venido implementando.Unidades agricolas familiares
Restitución y acceso suficiente a la tierr
Título: De censuris ecclesiasticis
No full textTít. en port. común: "Tractatus universi iuris, duce, et auspice Gregorio XIII Pontifice Maximo"Marca tip. de la "Società dell'aquila che si rinnova", en port. y colofónLugar y segunda fecha constan en colofónMarca tip. en port. y colofónSign.: A-Z\p8\s, 2A-2Z\p8\s, 3A-3E\p8\sPort. a dos tintasTexto a dos co
Título: De contractibus et aliis illicitis
No full textTít. en port. común: "Tractatus universi iuris, duce, et auspice Gregorio XIII Pontifice Maximo"Marca tip. de la "Società dell'aquila che si rinnova", en port. y colofónLugar y de nuevo fecha constan en colofónMarca tip. en port. y colofónSign.: A-Z\p8\s, 2A-2X\p8\s, 2Y\p10\sPort. a dos tintasTexto a dos co
¿Y si el Papa fuera una mujer?
Full text linkLa enorme presencia de mujeres en las más altas esferas del poder no puede ser un dato ignorado al momento de analizar la vitalidad del modo de vida patriarcal. Es más, se ha llegado a escuchar: si el Papa fuera mujer el aborto sería ley. Ciertamente una meta lejana. Pero esta tendencia podría prometer acercarla mediante, por ejemplo, la incorporación de mujeres al sacerdocio y a las instancias de decisión del Estado Vaticano. Es cierto que leer sólo de este modo esa consigna del Encuentro Nacional de Mujeres de 2012 sería un olvido imperdonable de la ironía en que se sostiene. Pero a los efectos de estas líneas no interesa la consigna en sí misma (transitoria, como toda consigna), sino una posible lectura (quizás no la del Encuentro) que ella tolera, a saber: ese camino amarillo del progreso que se nos propone como una salida de emergencia a los males del patriarcado. Estaríamos entonces frente a un debilitamiento o crisis del patriarcado; el esperado síntoma sería ese lugar de poder ganado para las mujeres.Fil: Sucksdorf, Cristián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Estudios de América Latina y el Caribe; Argentin
Título: De variis iuribus et acquisitionibus
No full textTít. en port. común: "Tractatus universi iuris, duce, et auspice Gregorio XIII Pontifice Maximo"Marca tip. de la "Società dell'aquila che si rinnova", en port. y colofónLugar y segunda fecha constan en colofónMarca tip. en port. y en colofónSign.: A-Z\p8\s, 2A-2Z\p8\s, 3A-3D\p8\s, 3E\p4\sPort. a dos tinta
Título: De dignitate et potestate seculari
No full textTít. en port. común: "Tractatus universi iuris, duce, et auspice Gregorio XIII Pontifice Maximo"Marca tip. de la "Società dell'aquila che si rinnova", en port. y colofónLugar y segunda fecha constan en colofónMarca tip. en port. y colofónSign.: A\p10\s, B-Z\p8\s, 2A-2Z\p8\s, 3A-3L\p8\s, 3M\p2\sPort. a dos tinta
Título: De probationibus
No full textTít. en port. común: "Tractatus universi iuris, duce, et auspice Gregorio XIII Pontifice Maximo"Marca tip. en port. y colofón de la "Società dell'aquila che si rinnova"La segunda fecha consta en colofónMarca tip. en port. y colofónSign.: A-Z\p8\s, 2A-2Z\p8\s, 3A-3G\p8\s, 3H\p4\sPort. a dos tintasTexto a dos co
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