Multiscale understanding of tricalcium silicate hydration reactions

Tricalcium silicate, the main constituent of Portland cement, hydrates to produce crystalline calcium hydroxide and calcium-silicate-hydrates (C-S-H) nanocrystalline gel. This hydration reaction is poorly understood at the nanoscale. The understanding of atomic arrangement in nanocrystalline phases is intrinsically complicated and this challenge is exacerbated by the presence of additional crystalline phase(s). Here, we use calorimetry and synchrotron X-ray powder diffraction to quantitatively follow tricalcium silicate hydration process: i) its dissolution, ii) portlandite crystallization and iii) C-S-H gel precipitation. Chiefly, synchrotron pair distribution function (PDF) allows to identify a defective clinotobermorite, Ca11Si9O28(OH)2.8.5H2O, as the nanocrystalline component of C-S-H. Furthermore, PDF analysis also indicates that C-S-H gel contains monolayer calcium hydroxide which is stretched as recently predicted by first principles calculations. These outcomes, plus additional laboratory characterization, yielded a multiscale picture for C-S-H nanocomposite gel which explains the observed densities and Ca/Si atomic ratios at the nano- and meso- scales.This work has been supported by Spanish MINECO through BIA2014-57658-C2-2-R, which is co-funded by FEDER, BIA2014-57658-C2-1-R and I3 (IEDI-2016-0079) grants. We also thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time at BL04-MSPD beamline

Situación actual y perspectivas de la producción de limón en España

Entre los principales factores que han contribuido a la expansión del limonero en España se pueden citar: la aptitud de las zonas productoras para una fruta de gran calidad, la formación con los patrones de combinaciones no sensibles a la tristeza, la llegada de las aguas del Trasvase Tajo-Segura, la expansión del riego por goteo, la seguridad en la comercialización y el bajo nivel de riesgo en los precios hasta el momento. A partir de los datos oficiales y de la información recogida directamente, se ha estudiado la evolución de la producción, precios y mercados y analizado la estacionalidad en los precios para una serie de valores quincenales de 14 años. Con los datos actuales, no puede decirse que se haya estabilizado el consumo en los diferentes mercados, pero subsiste la incertidumbre sobre la capacidad de absorción del incremento de producción esperado. Finalmente, se establecen una serie de consideraciones respecto a las perspectivas de la exportación y la influencia de los bajos rendimientos en la predicción de futuras producciones. La falta de saturación de la demanda ha sido la causa de que hasta el momento no se registren variaciones cíclicas en la producción. Es posible un mayor desarrollo del mercado interior, y debe aumentar la oferta en los meses con mayor índice de estacionalidad

Microorganisms present in artisanal fermented food from South America

Artisanal fermented products (foods and beverages) are produced in an artisanal way in many countries around the world. The main purpose of fermentation is to preserve the food, improve its safety, increase the nutritional and health-promoting value and add specific flavours. In South America, there is a great variety of fermented food produced in an artisanal way. Different raw materials are used such as potatoes, sweet potato, cassava, maize, rice, milk (cow, ewe, goat) and meat (beef, goat, lamb, llama and guanaco). Some of these fermented foods are typical of the region and are part of the culture of native communities, e.g. tocosh, masa agria, puba flour, charqui, chicha, champu and cauim among others (indigenous foods). However, other fermented foods produced in South America introduced by mainly European immigration, such as cheeses and dry sausages, and they are also produced in many different parts of the world. In this work, the microbial composition of the different artisanal fermented products produced in South America is reviewed, taking into consideration the associated raw materials, fermentation conditions and methodologies used for their production.Fil: Jimenez, María Eugenia. Teagasc - Irish Agriculture And Food Development Authority; Irlanda. Apc Microbiome Ireland; Irlanda. Universidad Nacional de Jujuy. Centro Interdisciplinario de Investigaciones en Tecnologías y Desarrollo Social para el Noa. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta-Jujuy. Centro Interdisciplinario de Investigaciones en Tecnologías y Desarrollo Social para el Noa; ArgentinaFil: O'Donovan, Ciara M.. Apc Microbiome Ireland; Irlanda. Teagasc - Irish Agriculture And Food Development Authority; IrlandaFil: Fernandez de Ullivarri, Miguel. Apc Microbiome Ireland; IrlandaFil: Cotter, Paul D.. Apc Microbiome Ireland; Irlanda. Teagasc - Irish Agriculture And Food Development Authority; Irland

Synchrotron Pair Distribution Function analyses of Ye’elimite-based pastes

The study of nanocrystalline phase atomic ordering is intrinsically complicated. The presence of additional crystalline phase(s) exacerbates this challenge. Here, we use the synchrotron pair distribution function (PDF) to characterize the local atomic order of the nanocrystalline phases in ye’elimite-containing pastes. Here, a multi r-range analysis approach has been used, where the 30–50 Å r-range allows determining the crystalline phase contents and the 1.6-35 Å is used to characterize the atomic ordering in the nanocrystalline components. Quantitative phase contents have been also derived from these analyses. Specifically, we have prepared five stoichiometric ye’elimite pastes with variable anhydrite and water contents. For the pastes without anhydrite addition, ettringite was not present and two calcium aluminium monosulfate phases were required for good PDF fits. In addition to crystalline AFm (c =28.6 Å), a nanocrystalline AFm phase with a significantly smaller c-unit cell parameter value, c =26.8 Å, was required having about 60 Å of particle size. For a paste obtained with 31 wt% of anhydrite addition, the main crystalline phase was ettringite with the aluminium hydroxide having nano-gibbsite local structure with a quite small average particle size, =35 ÅThis work has been supported by Spanish MINECO through BIA2014-57658-C2 and BIA2017-82391-R, which are co-funded by FEDER. PDF experiment was performed at ID15A beamline of ESR

Varietal Change Dominates Adoption of Technology in Spanish Citrus Production

After describing the technology adopted and its influence on production and yield, the importance of varietal change, which is essential to meet demand, is underscored. The choice of a variety by growers depends on the expected price it will fetch along with the commercial and crop characteristics and the quality. Survival of a variety in the marketplace depends on the performance as expected and on the existence of other more competitive varieties. First, in Spanish citrus farming, the navel group predominate, with 41.10% of orange production, in which the main varieties are "Navelina" and "Lanelate." The group of late white oranges is also important. The mandarin orange group includes clementines and mandarin hybrids; lemons also feature prominently. In sweet oranges, the navel group and late white group has often been renewed with varieties from the same group. In very early clementines varieties, the survival of which is usually short, the supply of new varieties is excessive. Because of its commercial characteristics and harvesting time, the group with the highest expansion possibilities are the mandarin hybrids which are in demand by hypermarkets. In the introduction of varieties, in recent years we have seen varietal clubs being established, with area control of each variety and very strict rules on cultivation and marketing

Las explotaciones hortofrutícolas del secano-mediterráneo: análisis desde una perspectiva multicriterio

En las últimas décadas se han producido numerosos cambios socioeconómicos y políticos que han provocado una clara transformación en la realidad agraria de las zonas del interior Mediterráneo español. Entre ellos es considerable el empuje creciente del sector industria o el de servicios, que al reclamar la mano de obra más joven de estas zonas, pone en duda la continuidad del relevo generacional en las explotaciones familiares. Otros fenómenos como la paulatina liberalización de la PAC y la reducción de las ayudas directas a los cultivos principales de estas zonas, como son el olivo, la vid de vinificación y el almendro, no favorecen precisamente su desarrollo económico. Estas comarcas tuvieron su base económica en una agricultura muy tradicional, pero ahora, cuando llega la hora de la liberización, se ven obligadas a la adopción de reestructuraciones para competir con otras producciones agrarias, de dentro o fuera de la UE, que se obtienen en condiciones más favorables. La falta de recursos tan limitantes para la producción agraria como puede ser el agua, ola dificultad y el alto coste de la mano de obra puntual que requieren estos cultivos, contribuye a desanimar al colectivo de empresarios agrícolas. De hecho la falta de alternativas que puedan tener una rentabilidad clara, o las escasas posibilidades de intensificar los modelos de producción existente, favorecen el continuo flujo hacia una agricultura a tiempo parcial. Todo esto supone la presencia de innumerables factores a tener en cuenta a la hora de la toma de decisiones en las explotaciones. Hoy en día no es posible basarse exclusivamente en un criterio económico, habrán que ser tenidos en cuenta otros aspectos, sociales, ambientales o tecnológicos que, igualmente, condicionan el sentido en que pueden evolucionar las explotaciones y toda una zona agraria

Economic evaluation of methyl bromide alternatives used on the east coast of Spain

Growers need alternatives to MB that are safe, consistent and cost-effective. Several projects were undertaken in the Mediterranean coast of Spain (Valencia and Murcia) to evaluate the cost of products and techniques tested as alternatives to methyl bromide (MB) on crops such as citrus, open-air horticulture, strawberry, and greenhouse-grown pepper.Telone (1,3-dichloropropene with chloropicrin) gave the most consistent and reliable results. There is interest in solarization, particularly when combined with chemical or biofumigants at low dose, however, in greenhouse-grown peppers have other costs associated with reducing the harvesting period. The use of grafted plants is a solution for watermelon and offers possibilities in other species. To compensate for possible increased costs for alternatives, Integrated Crop Production can be a solution as this adds value in some markets