Modelling Euro-Mediterranean Agricultural Trade

This paper examines the methodological problems to define a modelling approach to assess the impact of full or limited bilateral liberalisation of agricultural trade flows in the Euro-Mediterranean region. The bilateral trade liberalisation process in the region is framed by complexity, in policy instruments and in the characteristics of the products, in particular fruits and vegetables. Advantages and disadvantages of the general equilibrium and partial equilibrium approaches to simulate trade policy impacts are assessed. Caveats of existing models are related to the representation of specific policy instruments (tariffs, entry prices and other non-tariff measures) and on the seasonal nature of horticultural trade, which is of major importance in the Euro-Mediterranean Free Trade Are. The paper provides an illustration of how an imperfect substitute product model could be helpful to describe the trade effects of bilateral price changes, for given seasons.

F&V Trade Model to Assess Euro-Med Agreements. An Application to the Fresh Tomato Market

The complexity derived from the bilateral trade liberalisation process in the Mediterranean region is difficult to represent in a trade model, not only because of the range of instruments still constraining trade but also because of the special nature of the most important traded goods (product differentiation and seasonality). Tariff-rate quotas (TRQ's) and the entry price system are clearly defined on a monthly basis for the fruits and vegetables trade flows towards the European Union (EU). This point makes efforts to model such a trade in yearly basis not representative of reality. We propose a static partial equilibrium model tailored to model trade impacts of specific policy instruments which considers imports from different sources as imperfect substitutes, following the non-linear Armington type model. Different policy scenarios have been run using the model, considering changes in TRQ's and Entry Price regimes, its tariffication and preference erosion. The results of model runs show that, as regards to EU producers, bilateral trade liberalisation with extension of TRQs would be the least dramatic scenario. By contrast, the phasing out of the entry price system would have serious consequences on EU producers. The model has also given detailed information on Morocco's interests in the negotiation, although it could easily include a larger number of suppliers. Morocco appears to be interested in multilateral liberalisation as well as in bilateral liberalisation. In fact, multilateral liberalisation will not cause a great deal of preference erosion against Moroccan exporters, unless tariff reductions only affect MFN suppliers.International Relations/Trade,

Clinkering and hydration study of non-active and active Belite-Alite-Ye'elimite (BAY) cements

The aim of AIM is to promote industry-driven, interdisciplinary research in material science and engineering in order to provide leading-edge, sustainable solutions to the challenges facing engineers in today’s changing society and environment. http://www.ucl.ac.uk/aim/conference-info/37ccsThe manufacturing process of ye'elimite rich cements emit about 15-37% less CO2 to the atmosphere than OPC. Cements that contain belite, ye’elimite and ferrite, known as BYF cements, are promising eco-friendly binders. However, belite, their main phase, shows a slow hydrating behaviour; therefore the corresponding mortars present lower mechanical strengths than OPC at early ages. To solve this problem, BYF clinkers can be activated by: i) forming alite jointly with belite and ye’elimite during clinkering, known as BAY clinkers. The alite and ye’elimite reaction with water should develop high mechanical strengths at early ages, besides, belite contributes to later curing times. ii) A second activation is based on the stabilisation of alpha forms of belite by dopants. The objective of this work is to obtain two types of BAY clinkers (standard and active BAY) using CaF2 as mineraliser and borax as dopant agent to stabilize alpha forms of belite phase. After that, anhydrite was added as sulphate source to obtain the corresponding cements. The hydration behaviour of these cements has been studied through rheological and x-ray diffraction measurements, the latter combined with Rietveld quantitative phase analysis. In addition, mechanical and dimensional properties of BAY mortars are also presented and discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Advanced synchrotron studies of ye'elimite-based cement pastes

Synchrotron characterization techniques [1] are being used to study Portland-based cements and recently also CSA and related cements. A key property of these techniques is that they do not require sample preparation, so the microstructures of the pastes can be preserved. The classical application of synchrotron tools is powder diffraction used to determine the crystalline phase content evolution with hydration including the overall amorphous fraction. Furthermore, other most advanced techniques are being applied to ye'elimite-containing pastes such as i) Total Scattering Synchrotron Powder Diffraction (TS-SXPD), and ii) Ptychographic Synchrotron X-ray Computed Tomography (PSXCT). All these applications will be reviewed here. TS-SXPD data coupled with the Pair Distribution Function (PDF) analysis methodology [2] allows having a better insight about the nanocrystalline/amorphous atomic arrangements in the gels. It has been very recently shown that nanogibbsite with very small particles, 3nm, is the main constituent of ye'elimite-gypsum hydration paste [2]. Nanogibbsite particles being smaller than those originated from the hydration of monocalcium aluminate. In addition, PSXCT is a tomographic technique that profits from the partly coherent nature of the synchrotron beam to provide better (smaller) resolution, which can be lower than 100 nm. It also provides the mass densities if the chemical stoichiometries are known. This technique has been applied to ye'elimite hydration to determine the microstructure and chiefly the bulk densities of nanogibbsite [3]. The microstructure evolution at early age was also followed [4]. Figure 1 shows an example of a slide of the electron density tomogram for a ye'elimite paste at 8 days of hydration and the corresponding histogram for the full volume with all phases identified.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.This work has been supported by Spanish MINECO through BIA2014-57658-C2 and BIA2017-82391-R, which are co-funded by FEDER

Early hydration study of standard and doped Alite-Belite-Ye’elimite (ABY) cements through Synchrotron Radiation

The manufacturing of ye'elimite-rich cements releases from 15 to 37%, depending on their composition, less CO2 to the atmosphere than ordinary Portland cement (OPC). BYF cements containing belite, ye’elimite and ferrite as main crystalline phases, are promising eco-friendly binders. Nevertheless, belite, its main phase, shows a slow hydrating behaviour and the mechanical strengths are lower than OPC at early ages. Some alternatives to solve this problem are: i) forming alite jointly with belite and ye’elimite during clinkering, Alite Belite Ye’elimite (ABY) clinkers. The hydration of alite and ye’elimite would develop high mechanical strengths at early ages, and belite contributes to later curing times; ii) a second alternative is the stabilisation of alpha forms of belite using dopants such as boron named here after dABY. In this work, two different types of ABY clinkers (standard and doped) have been prepared and characterized to understand their different hydration mechanisms at the same water-to-cement (w/c) ratio. The clinkers have been prepared using CaF2 and ZnO as mineralizers, and borax as dopant agent to stabilize alpha forms of belite (’H-C2S). Afterwards, 14 wt% of anhydrite (as soluble sulphate source) was added to prepare the corresponding cements. Finally, the hydration study was performed at w/c ratio of 0.5. Here, an in-situ hydration study using synchrotron X-ray powder diffraction (SXRPD) for the first 14 hours of hydration is reported. Moreover, these results will be combined with the ex-situ laboratory X-ray powder diffraction study (LXRPD) at 1 day of hydration and calorimetric results. Rietveld quantitative phase analysis has been used to establish the phase evolution across the time.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO ( BIA2017-82391-R), co-funded by FEDER, and I3 [IEDI-2016-0079]

Water-to-cement ratio influence on low-carbon cements performances

Portland Cement (PC) is the most important active ingredient in most of the construction concrete. However, the PC production is associated with a high carbon dioxide release (around 1 ton of CO2 per ton of PC). One approach to reduce CO2 emissions consists on the reformulation of the clinker with less calcite demanding phases, such as, belite rich clinkers. The drawback of this kind of clinkers is the low reactivity of belite (beta-belite). In order to compensate this problem, belite rich clinkers can be prepared with ye’elimite and ferrite or with alite [known as belite-ye’elimite-ferrite (BYF) and belite-alite-ye’elimite (BAY), respectively]. In addition, it can be improved by using a high reactive belite polymorph, such as alpha-belite. In this work, the hydration and mechanical behaviour of BYF and BAY cements (with beta and/or alpha-belite) with different water-to-cement ratios have been studied. The clinkers were produced using natural raw materials, and were mixed with anhydrite (CaSO4) to prepare the corresponding cements. At early ages, the main hydration products of these cements were ettringite, calcium monosulfoaluminate and amorphous aluminium hydroxide. At later ages, stratlingite, katoite and amorphous C-S-H were found. The compressive strength values of the corresponding mortars were correlated with the mineralogy evolution of the pastes (mainly obtained by XRD and TGA).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. I3-Ramón y Cajal Universidad de Malag

Urban ageing, gender and the value of the local environment: The experience of older women in a central neighbourhood of Madrid, Spain

This article belongs to the Special Issue Land, Ageing, Gender and Environment: Problems and Challenges from Different Disciplines.Urban ageing is an emerging domain that mixes two challenges of current societies: the ageing of the population and the increasing urbanisation. While ageing in place has demonstrated numerous benefits, some social sectors question whether the city is the right environment for ageing, since cities are home to many of the social problems that characterise contemporary societies. Urban environments are widely described as rootless in most academic articles, with a focus on the impersonality, transience, and segmentation of links between city dwellers. However, this portrayal coexists with contrasting views of urban life that instead emphasise the importance of the local setting and other experiences of attachment to the place of residence. From the age and gender perspectives, in some urban areas, the neighbourhood plays a fundamental role in the lives of many older women, as a natural setting for interaction and an area conducive to collaborative relationships and practical and emotional support in times of need. This article analyses the role that the local space plays in the lives of older women, the value they attach to it and the meaning they attribute to neighbourhood relations in the local urban environment. In order to analyse this reality, the Universidad (Malasaña) neighbourhood, has been selected as a case study, a central area in Madrid (Spain) exposed to numerous processes of transformation, which shows the highest rate of residential mobility in the area. Despite this reality, in a context marked by new difficulties, the conclusion shows that elderly women have a strong attachment to their neighbourhood. This attachment is not necessarily characterised by deep friendships, but by the existence of a significant social network that responds in case of need

Synchrotron x-ray pair distribution function: A tool to characterize cement gels

Cement matrices contain large amounts of crystalline phases jointly with amorphous and/or nanocrystalline phases. Consequently, their analyses are very challenging. Synchrotron powder diffraction in combination with the pair distribution function (PDF) methodology is very useful to characterize such complex cement pastes. This work is focused on the study of the short and medium range atomic arrangement(s) in the different nanocrystalline gels which are present in the cement pastes through total scattering Pair Distribution Function quantitative phase analyses.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Acknowledgments: We thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time and the financial support by BIA2014-57658-C2-1-R and BIA2014-57658-C2-2-R, which is co-funded by FEDER. We also thank Dr. Monica Dapiaggi for her contribution with the PDF study of Ca(OH)2 monolayer

Rietveld Quantitative Phase Analysis of Oil Well Cement: in Situ Hydration Study at 150 Bars and 150 °C

Oil and gas well cements are multimineral materials that hydrate under high pressure and temperature. Their overall reactivity at early ages is studied by a number of techniques including through the use of the consistometer. However, for a proper understanding of the performance of these cements in the field, the reactivity of every component, in real‐world conditions, must be analysed. To date, in situ high energy synchrotron powder diffraction studies of hydrating oil well cement pastes have been carried out, but the quality of the data was not appropriated for Rietveld quantitative phase analyses. Therefore, the phase reactivities were followed by the inspection of the evolution of non‐overlapped diffraction peaks. Very recently, we have developed a new cell specially designed to rotate under high pressure and temperature. Here, this spinning capillary cell is used for in situ studies of the hydration of a commercial oil well cement paste at 150 bars and 150 °C. The powder diffraction data were analysed by the Rietveld method to quantitatively determine the reactivities of each component phase. The reaction degree of alite was 90% after 7 hours, and that of belite was 42% at 14 hours. These analyses are accurate, as the in situ measured crystalline portlandite content at the end of the experiment, 12.9 wt%, compares relatively well with the value determined ex situ by thermal analysis, i.e., 14.0 wt%. The crystalline calcium silicates forming at 150 bars and 150 °C are also discussed.This research was funded by Spanish MINECO, grant number BIA2017‐82391‐R which is co‐funded by FEDER. We thank Marc Malfois for his help during the experiment performed at NCD‐SWEET beamline at ALBA synchrotron. We also thank Marcus Paul (Dyckerhoff GmbH) for providing the OWC sample with its characterization and helpful discussions

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below 5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s) may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF) chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the ~4–7 nm r-range allows determining the crystalline phase contents; the ~1–2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the ~0.2–1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca11Si9O28(OH)2 8.5H2O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye’elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nmThis 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. Finally, we thank Prof. Simon Billinge, Long Yang and Monica Dapiaggi for their help with the PDF script and simulations for Ca(OH)2 scattering dat