Alkaline activation of metakaolin. Effect of the soluble silicate addition and curing temperature

[ES] El objetivo del presente trabajo es determinar el efecto que la cantidad de sílice soluble presente en la disolución activadora (relación molar SiO2/Na2O entre 0 y 0.69) y la temperatura de curado (85ºC, 150ºC y 200ºC) ejercen sobre las propiedades físico-mecánicas y las características mineralógicas y microestructurales de los productos formados por activación alcalina de metacaolín. Para ello se determinaron los valores de resistencia mecánica a compresión de los materiales objeto de estudio y se realizó un estudio mineralógico y microestructural de los mismos por DRX, SEM-EDX, 29Si RMN-MAS y porosimetría de mercurio. Los resultados obtenidos muestran que la resistencia mecánica del material guarda una estrecha relación con la naturaleza, microestructura y composición química de los productos de reacción así como con las condiciones de curado. En todos los casos se genera, como principal producto de reacción, un polímero inorgánico alcalino con propiedades cementantes (gel N-A-S-H) responsable, en mayor medida, de las propiedades mecánicas del material. Como productos secundarios se forman algunas zeolitas cuya proporción y tipo (sodalita, zeolita A, faujasita, …) dependen tanto de la naturaleza del activador como de las condiciones de curado. La presencia de sílice soluble en la disolución activadora conduce a la formación de geles con una mayor relación Si/Al y a la ralentización de la zeolitización, factores, ambos, con un efecto positivo sobre la resistencia mecánica. Con respecto a la temperatura de curado, existe un valor umbral, en función de la composición del material, a partir del cual un incremento en dicha temperatura deja de tener efectos positivos sobre la evolución de la resistencia mecánica.[EN] This study has been undertaken to determine the effect that the soluble silica content in the activating solution (molar ratio SiO2/Na2O between 0 and 0.69) and curing temperature (85ºC, 150ºC, and 200ºC) have on the physico-mechanical properties and mineralogical and microstructural characteristics of products formed by alkaline activation of metakaolin. The compression strength of the materials obtained was determined and a mineralogical and microstructural study of these materials was conducted by XRD, SEM-EDX, 29Si MAS-NMR, and mercury porosimetry. The results show that the mechanical strength of the material is closely related to the nature, microstructure, and chemical composition of the reaction products, as well as to the curing conditions. In all cases, the main reaction product that forms is an inorganic alkaline polymer with cementing properties (N-A-S-H gel), which is largely responsible for the mechanical properties of the material. Some zeolites form as by-products, whose quantity and type (sodalite, zeolite A, faujasite, etc.) depend on the nature of the activator and the curing conditions. The presence of soluble silica in the activating solution leads to the formation of gels with a larger Si/Al ratio and slower zeolitisation, these both being factors with a positive effect on mechanical strength. The curing temperature exhibits a threshold value that depends on the composition of the material, beyond which an increase in curing temperature ceases to positively affect the evolution of the material’s mechanical strength.Programa de Alta Especialización en Tecnologías Industriales “Nuevas técnicas y recubrimientos cerámicos de baja temperatura” (IMAETA/2004/15-IMAETB/2005/12-IMAETB/2006/18) financiado por el Instituto de la Pequeña y Mediana Industria de la Generalitat Valenciana (IMPIVA) y a la Uunión Europea (Fondo Social Europeo), a la Dirección General de Investigación Científica y Técnica por la financiación del proyecto BIA2004-04835 y al CSIC/Fondo Social Europeo por el contrato de investigador en prácticas REF I3P-PC2004L.Peer reviewe

Estudio del comportamiento de diversos residuos de catalizadores de craqueo catalítico (FCC) en cemento Portland

The fluidized-bed catalytic cracking catalyst (FCC) it is a residue from the industry of the petroleum that shows a high pozzolanic reactivity and, in cementing matrix, it significantly improves their mechanical behaviour as well as durability. In this research a comparative study on residues of catalyst from different sources has been carried out, in order to know if these residues can be used jointly in an indiscriminate way or, on the contrary, it is necessary to classify them according to their characteristics. Thus, a study on five different FCC residues, supplied from different companies, has been carried out, and their physical-chemical characteristics, pozzolanic reactivity by means of thermogravimetric analysis and the evolution of the mechanical strength of mortars were studied. After analyzing all the aspects, it can be concluded that no significant differences among the different tested catalysts were found.El catalizador de craqueo catalítico (FCC) es un residuo de la industria del petróleo que posee una elevada reactividad puzolánica y en matrices cementicias mejora de manera importante los aspectos mecánicos así como de durabilidad. En este trabajo se realiza un estudio comparativo sobre residuos de catalizador de distintos orígenes, para poder conocer si se pueden utilizar conjuntamente de forma indiscriminada o por el contrario hay que catalogarlos según su origen. Para ello, se realizó un estudio sobre cinco residuos de catalizador de craqueo catalítico distintos, suministrados por diferentes empresas y se estudiaron sus características fisicoquímicas, reactividad puzolánica a través de estudios termogravimétricos y la evolución de las resistencias mecánicas en morteros. Tras analizar todos los aspectos se concluye que no existen diferencias significativas entre los distintos catalizadores empleados

Assessing the capabilities of high-resolution spectral, altimetric, and textural descriptors for mapping the status of citrus parcels

[EN] Agricultural land abandonment is an increasing phenomenon around the world with relevant environmental and socio-economic implications. In the European Union about 11 % of agricultural land is at high risk of abandonment. The Comunitat Valenciana region (Spain) is the most important citrus producer in Europe suffering from this problem. Identifying the status of citrus crops at the parcel level is essential for policymakers in agriculture. This work assessed the use of WorldView-3 data, Very High-Resolution Airborne Images, and Structure from Motion point clouds to identify the status of citrus parcels using two machine learning algorithms: Random Forest and Support Vector Machines. Different analyses involving combinations of the three data sources were carried out to assess the impact on classification accuracy. The results showed the high potential of airborne imagery (OA ¿ 0.967) and WorldView-3 (OA ¿ 0.936) to detect parcel status using a single image. The SfM data showed a lower potential (OA ¿ 0.825). Adding SfM point cloud to the multispectral information produced small improvements (0.4¿2.0 %) in classification accuracy. The class separability analysis showed the importance of WV-3 SWIR bands to detect abandoned parcels as they produce more spectral separability over the productive parcels in the 1570 nm ¿ 2330 nm spectrum. The results also show the importance of GLCM texture features extracted from sub-metric images due to their ability to model spatial planting patterns typical of fruit cropsThis research was funded by regional government of Spain, Generalitat Valenciana, within the framework of the research project AICO/2020/246. Funding for open access charge: CRUE-Universitat Politecnica de Valencia.Morell-Monzó, S.; Estornell Cremades, J.; Sebastiá-Frasquet, M. (2023). Assessing the capabilities of high-resolution spectral, altimetric, and textural descriptors for mapping the status of citrus parcels. Computers and Electronics in Agriculture. 204:1-11. https://doi.org/10.1016/j.compag.2022.10750411120

Comparison of Sentinel-2 and High-Resolution Imagery for Mapping Land Abandonment in Fragmented Areas

[EN] Agricultural land abandonment is an important environmental issue in Europe. The proper management of agricultural areas has important implications for ecosystem services (food production, biodiversity, climate regulation and the landscape). In the coming years, an increase of abandoned areas is expected due to socio-economic changes. The identification and quantification of abandoned agricultural plots is key for monitoring this process and for applying management measures. The Valencian Region (Spain) is an important fruit and vegetable producing area in Europe, and it has the most important citrus industry. However, this agricultural sector is highly threatened by diverse factors, which have accelerated land abandonment. Landsat and MODIS satellite images have been used to map land abandonment. However, these images do not give good results in areas with high spatial fragmentation and small-sized agricultural plots. Sentinel-2 and airborne imagery shows unexplored potential to overcome this thanks to higher spatial resolutions. In this work, three models were compared for mapping abandoned plots using Sentinel-2 with 10 m bands, Sentinel-2 with 10 m and 20 m bands, and airborne imagery with 1 m visible and near-infrared bands. A pixel-based classification approach was used, applying the Random Forests algorithm. The algorithm was trained with 144 plots and 100 decision trees. The results were validated using the hold-out method with 96 independent plots. The most accurate map was obtained using airborne images, the Enhanced Vegetation Index (EVI) and Thiam's Transformed Vegetation Index (TTVI), with an overall accuracy of 88.5%. The map generated from Sentinel-2 images (10 m bands and the EVI and TTVI spectral indices) had an overall accuracy of 77.1%. Adding 20 m Sentinel-2 bands and the Normalized Difference Moisture Index (NDMI) did not improve the classification accuracy. According to the most accurate map, 4310 abandoned plots were detected in our study area, representing 32.5% of its agricultural surface. The proposed methodology proved to be useful for mapping citrus in highly fragmented areas, and it can be adapted to other crops.Morell-Monzó, S.; Estornell Cremades, J.; Sebastiá-Frasquet, M. (2020). Comparison of Sentinel-2 and High-Resolution Imagery for Mapping Land Abandonment in Fragmented Areas. Remote Sensing. 12(12):1-18. https://doi.org/10.3390/rs12122062S1181212MacDonald, D., Crabtree, J. ., Wiesinger, G., Dax, T., Stamou, N., Fleury, P., … Gibon, A. (2000). Agricultural abandonment in mountain areas of Europe: Environmental consequences and policy response. Journal of Environmental Management, 59(1), 47-69. doi:10.1006/jema.1999.0335Kosmas, C., Kairis, O., Karavitis, C., Acikalin, S., Alcalá, M., Alfama, P., … Solé-Benet, A. (2015). An exploratory analysis of land abandonment drivers in areas prone to desertification. CATENA, 128, 252-261. doi:10.1016/j.catena.2014.02.006Corbelle Rico, E., & Crecente Maseda, R. (2018). Estudio da evolución da superficie agrícola na comarca da Terra Chá a partir de fotografía aérea histórica e mapas de usos, 1956-2004. Recursos Rurais, (4), 57-65. doi:10.15304/rr.id5312Gellrich, M., Baur, P., Koch, B., & Zimmermann, N. E. (2007). Agricultural land abandonment and natural forest re-growth in the Swiss mountains: A spatially explicit economic analysis. Agriculture, Ecosystems & Environment, 118(1-4), 93-108. doi:10.1016/j.agee.2006.05.001Rey Benayas, J. M. (2007). Abandonment of agricultural land: an overview of drivers and consequences. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2(057). doi:10.1079/pavsnnr20072057Árgyelán, T. (2015). Abandonment phenomenon in Europe. Acta Universitatis Sapientiae, Agriculture and Environment, 7(1), 89-97. doi:10.1515/ausae-2015-0008Citricultura Valenciana: Gestión Integrada de Plagas y Enfermedades en Cítricoshttp://gipcitricos.ivia.es/citricultura-valencianaRounsevell, M. D. A., Reginster, I., Araújo, M. B., Carter, T. R., Dendoncker, N., Ewert, F., … Tuck, G. (2006). A coherent set of future land use change scenarios for Europe. Agriculture, Ecosystems & Environment, 114(1), 57-68. doi:10.1016/j.agee.2005.11.027Verburg, P. H., Schulp, C. J. E., Witte, N., & Veldkamp, A. (2006). Downscaling of land use change scenarios to assess the dynamics of European landscapes. Agriculture, Ecosystems & Environment, 114(1), 39-56. doi:10.1016/j.agee.2005.11.024Dubinin, M., Potapov, P., Lushchekina, A., & Radeloff, V. C. (2010). Reconstructing long time series of burned areas in arid grasslands of southern Russia by satellite remote sensing. Remote Sensing of Environment, 114(8), 1638-1648. doi:10.1016/j.rse.2010.02.010Ruiz-Flan˜o, P., Garci´a-Ruiz, J. M., & Ortigosa, L. (1992). Geomorphological evolution of abandoned fields. A case study in the Central Pyrenees. CATENA, 19(3-4), 301-308. doi:10.1016/0341-8162(92)90004-uFischer, J., Hartel, T., & Kuemmerle, T. (2012). Conservation policy in traditional farming landscapes. Conservation Letters, 5(3), 167-175. doi:10.1111/j.1755-263x.2012.00227.xPenov, I. (2004). The Use of Irrigation Water in Bulgaria’s Plovdiv Region During Transition. Environmental Management, 34(2), 304-313. doi:10.1007/s00267-004-0019-8Novara, A., Gristina, L., Sala, G., Galati, A., Crescimanno, M., Cerdà, A., … La Mantia, T. (2017). Agricultural land abandonment in Mediterranean environment provides ecosystem services via soil carbon sequestration. Science of The Total Environment, 576, 420-429. doi:10.1016/j.scitotenv.2016.10.123Cerdà, A., Ackermann, O., Terol, E., & Rodrigo-Comino, J. (2019). Impact of Farmland Abandonment on Water Resources and Soil Conservation in Citrus Plantations in Eastern Spain. Water, 11(4), 824. doi:10.3390/w11040824Rey Benayas, J. M., & Bullock, J. M. (2012). Restoration of Biodiversity and Ecosystem Services on Agricultural Land. Ecosystems, 15(6), 883-899. doi:10.1007/s10021-012-9552-0Shrivastava, R. J., & Gebelein, J. L. (2007). Land cover classification and economic assessment of citrus groves using remote sensing. ISPRS Journal of Photogrammetry and Remote Sensing, 61(5), 341-353. doi:10.1016/j.isprsjprs.2006.10.003Löw, F., Prishchepov, A., Waldner, F., Dubovyk, O., Akramkhanov, A., Biradar, C., & Lamers, J. (2018). Mapping Cropland Abandonment in the Aral Sea Basin with MODIS Time Series. Remote Sensing, 10(2), 159. doi:10.3390/rs10020159Alcantara, C., Kuemmerle, T., Prishchepov, A. V., & Radeloff, V. C. (2012). Mapping abandoned agriculture with multi-temporal MODIS satellite data. Remote Sensing of Environment, 124, 334-347. doi:10.1016/j.rse.2012.05.019Estel, S., Kuemmerle, T., Alcántara, C., Levers, C., Prishchepov, A., & Hostert, P. (2015). Mapping farmland abandonment and recultivation across Europe using MODIS NDVI time series. Remote Sensing of Environment, 163, 312-325. doi:10.1016/j.rse.2015.03.028Dara, A., Baumann, M., Kuemmerle, T., Pflugmacher, D., Rabe, A., Griffiths, P., … Hostert, P. (2018). Mapping the timing of cropland abandonment and recultivation in northern Kazakhstan using annual Landsat time series. Remote Sensing of Environment, 213, 49-60. doi:10.1016/j.rse.2018.05.005Müller, D., Leitão, P. J., & Sikor, T. (2013). Comparing the determinants of cropland abandonment in Albania and Romania using boosted regression trees. Agricultural Systems, 117, 66-77. doi:10.1016/j.agsy.2012.12.010Yin, H., Prishchepov, A. V., Kuemmerle, T., Bleyhl, B., Buchner, J., & Radeloff, V. C. (2018). Mapping agricultural land abandonment from spatial and temporal segmentation of Landsat time series. Remote Sensing of Environment, 210, 12-24. doi:10.1016/j.rse.2018.02.050Kuemmerle, T., Hostert, P., Radeloff, V. C., van der Linden, S., Perzanowski, K., & Kruhlov, I. (2008). Cross-border Comparison of Post-socialist Farmland Abandonment in the Carpathians. Ecosystems, 11(4), 614-628. doi:10.1007/s10021-008-9146-zGrădinaru, S. R., Kienast, F., & Psomas, A. (2019). Using multi-seasonal Landsat imagery for rapid identification of abandoned land in areas affected by urban sprawl. Ecological Indicators, 96, 79-86. doi:10.1016/j.ecolind.2017.06.022Prishchepov, A. V., Radeloff, V. C., Dubinin, M., & Alcantara, C. (2012). The effect of Landsat ETM/ETM + image acquisition dates on the detection of agricultural land abandonment in Eastern Europe. Remote Sensing of Environment, 126, 195-209. doi:10.1016/j.rse.2012.08.017Baumann, M., Kuemmerle, T., Elbakidze, M., Ozdogan, M., Radeloff, V. C., Keuler, N. S., … Hostert, P. (2011). Patterns and drivers of post-socialist farmland abandonment in Western Ukraine. Land Use Policy, 28(3), 552-562. doi:10.1016/j.landusepol.2010.11.003Szostak, M., Hawryło, P., & Piela, D. (2017). Using of Sentinel-2 images for automation of the forest succession detection. European Journal of Remote Sensing, 51(1), 142-149. doi:10.1080/22797254.2017.1412272Kanjir, U., Đurić, N., & Veljanovski, T. (2018). Sentinel-2 Based Temporal Detection of Agricultural Land Use Anomalies in Support of Common Agricultural Policy Monitoring. ISPRS International Journal of Geo-Information, 7(10), 405. doi:10.3390/ijgi7100405Proisy, C., Viennois, G., Sidik, F., Andayani, A., Enright, J. A., Guitet, S., … Suhardjono. (2018). Monitoring mangrove forests after aquaculture abandonment using time series of very high spatial resolution satellite images: A case study from the Perancak estuary, Bali, Indonesia. Marine Pollution Bulletin, 131, 61-71. doi:10.1016/j.marpolbul.2017.05.056Thanh Noi, P., & Kappas, M. (2017). Comparison of Random Forest, k-Nearest Neighbor, and Support Vector Machine Classifiers for Land Cover Classification Using Sentinel-2 Imagery. Sensors, 18(2), 18. doi:10.3390/s18010018Maxwell, A. E., Warner, T. A., & Fang, F. (2018). Implementation of machine-learning classification in remote sensing: an applied review. International Journal of Remote Sensing, 39(9), 2784-2817. doi:10.1080/01431161.2018.1433343https://rdrr.io/cran/raster/https://cran.r-project.org/web/packages/rgdal/index.htmlHuete, A., Justice, C., & Liu, H. (1994). Development of vegetation and soil indices for MODIS-EOS. Remote Sensing of Environment, 49(3), 224-234. doi:10.1016/0034-4257(94)90018-3Wilson, E. H., & Sader, S. A. (2002). Detection of forest harvest type using multiple dates of Landsat TM imagery. Remote Sensing of Environment, 80(3), 385-396. doi:10.1016/s0034-4257(01)00318-2Silleos, N. G., Alexandridis, T. K., Gitas, I. Z., & Perakis, K. (2006). Vegetation Indices: Advances Made in Biomass Estimation and Vegetation Monitoring in the Last 30 Years. Geocarto International, 21(4), 21-28. doi:10.1080/10106040608542399Huete, A. . (1988). A soil-adjusted vegetation index (SAVI). Remote Sensing of Environment, 25(3), 295-309. doi:10.1016/0034-4257(88)90106-xGitelson, A. A., Kaufman, Y. J., & Merzlyak, M. N. (1996). Use of a green channel in remote sensing of global vegetation from EOS-MODIS. Remote Sensing of Environment, 58(3), 289-298. doi:10.1016/s0034-4257(96)00072-7Breiman, L. (2001). Machine Learning, 45(1), 5-32. doi:10.1023/a:1010933404324Gislason, P. O., Benediktsson, J. A., & Sveinsson, J. R. (2006). Random Forests for land cover classification. Pattern Recognition Letters, 27(4), 294-300. doi:10.1016/j.patrec.2005.08.011Breiman, L. (1996). Bagging predictors. Machine Learning, 24(2), 123-140. doi:10.1007/bf00058655Pal, M. (2005). Random forest classifier for remote sensing classification. International Journal of Remote Sensing, 26(1), 217-222. doi:10.1080/01431160412331269698Olofsson, P., Foody, G. M., Herold, M., Stehman, S. V., Woodcock, C. E., & Wulder, M. A. (2014). Good practices for estimating area and assessing accuracy of land change. Remote Sensing of Environment, 148, 42-57. doi:10.1016/j.rse.2014.02.015Whiteside, T. G., Maier, S. W., & Boggs, G. S. (2014). Area-based and location-based validation of classified image objects. International Journal of Applied Earth Observation and Geoinformation, 28, 117-130. doi:10.1016/j.jag.2013.11.009Morell Monzó, S., & Membrado-Tena, J. C. (2019). Causas y consecuencias del crecimiento urbanístico en el litoral valenciano a través de la evolución de los usos del suelo. El caso de Oliva. Cuadernos de Turismo, (44), 303-326. doi:10.6018/turismo.44.404861Smith, P., House, J. I., Bustamante, M., Sobocká, J., Harper, R., Pan, G., … Pugh, T. A. M. (2015). Global change pressures on soils from land use and management. Global Change Biology, 22(3), 1008-1028. doi:10.1111/gcb.1306

Land Use Classification of VHR Images for Mapping Small-Sized Abandoned Citrus Plots by Using Spectral and Textural Information

[EN] Agricultural land abandonment is an increasing problem in Europe. The Comunitat Valenciana Region (Spain) is one of the most important citrus producers in Europe suffering this problem. This region characterizes by small sized citrus plots and high spatial fragmentation which makes necessary to use Very High-Resolution images to detect abandoned plots. In this paper spectral and Gray Level Co-Occurrence Matrix (GLCM)-based textural information derived from the Normalized Difference Vegetation Index (NDVI) are used to map abandoned citrus plots in Oliva municipality (eastern Spain). The proposed methodology is based on three general steps: (a) extraction of spectral and textural features from the image, (b) pixel-based classification of the image using the Random Forest algorithm, and (c) assignment of a single value per plot by majority voting. The best results were obtained when extracting the texture features with a 9 x 9 window size and the Random Forest model showed convergence around 100 decision trees. Cross-validation of the model showed an overall accuracy of the pixel-based classification of 87% and an overall accuracy of the plot-based classification of 95%. All the variables used are statistically significant for the classification, however the most important were contrast, dissimilarity, NIR band (720 nm), and blue band (620 nm). According to our results, 31% of the plots classified as citrus in Oliva by current methodology are abandoned. This is very important to avoid overestimating crop yield calculations by public administrations. The model was applied successfully outside the main study area (Oliva municipality); with a slightly lower accuracy (92%). This research provides a new approach to map small agricultural plots, especially to detect land abandonment in woody evergreen crops that have been little studied until now.This research was funded by regional government of Spain, Generalitat Valenciana, within the framework of the research project AICO/2020/246 and the APC was also funded by the research project AICO/2020/246.Morell-Monzó, S.; Sebastiá-Frasquet, M.; Estornell Cremades, J. (2021). Land Use Classification of VHR Images for Mapping Small-Sized Abandoned Citrus Plots by Using Spectral and Textural Information. Remote Sensing. 13(4):1-18. https://doi.org/10.3390/rs13040681S11813

L'atenció educativa a l'alumnat d'alta capacitat en el sistema educatiu valencià

L’atenció educativa a l’alumnat d’alta capacitat continua plantejant molts dubtes i incerteses en el sistema educatiu actual. L’objectiu d’aquesta tesi és explicar (diagnosticar i analitzar) quina és la resposta educativa que rep actualment l'alumnat d'altes capacitats en el sistema educatiu valencià, amb la intenció d’elaborar propostes de millora educativa. El disseny de la investigació respon a tres tipus estudi: un estudi documental, un estudi de tipus descriptiu-correlacional de tipus quantitatiu i una anàlisi de grups de discussió de tipus qualitatiu. L’estudi documental ha servit per revisar quina és la formació inicial i contínua que s’ofereix als professionals de l’educació. L’estudi descriptiu correlacional ha analitzat les següents dimensions: formació rebuda, coneixements sobre l’alta capacitat, creences i actituds, coneixement de la legislació vigent i resposta educativa aplicada a l’alumnat d’alta capacitat. Les dades s’han recollit a través de dos qüestionaris realitzats ad hoc, un dirigit al professorat i l’altre als professionals de l’orientació educativa. Finalment, s’han plantejat dos grups de discussió: un de famílies i l’altre d’alumnat d’alta capacitat. L’anàlisi de les dades recollides mostra que la formació inicial de docents i professionals de l’orientació sembla més orientada al dèficit que a la promoció del talent i a obviar la importància de treballar amb l’alumnat d’alta capacitat. S’evidencia, a més de la manca de formació de base, que molts dels professionals de l’educació se senten poc capacitats per atendre l’alumnat d’alta capacitat. Per tant, el fet d’haver rebut formació tampoc no garanteix que aquesta tinga una transferència directa a l’aula. D’altra banda, són els i les professionals més joves els qui mostren un millor coneixement i una visió menys estereotipada i més lliure de prejudicis cap a l’alta capacitat. En canvi, no existeix una relació significativa entre els coneixements i les actituds en base a la formació rebuda. Són per tant les generacions més joves les que parteixen d’una visió menys estereotipada cap a l’alta capacitat. Pel que fa al coneixement de la legislació vigent, s’hi manifesta un clar desconeixement de la legislació vigent per part dels docents, però no en el cas dels i les professionals de l’orientació, sobretot entre aquells que treballen a l’educació pública i porten més temps treballant. Per acabar, en relació a quina és la resposta educativa que rep l’alumnat amb altes capacitats actualment al sistema educatiu valencià, les dades recollides mostren una manca de planificació a llarg termini, de coordinació entre etapes (o fins i tot dins la mateixa etapa) i de capacitat d’establir un itinerari clar i coherent que done la resposta que l’alumne/a necessita. En última instància, la proposta d’intervenció que es planteja en aquesta tesi aborda la necessitat d’orientar el sistema educatiu cap al desenvolupament del talent de l’alumnat, i no cap al dèficit, com ocorre en el sistema educatiu actual. És partint d’aquesta base que cal emmarcar la resposta específica a l’alumnat d’alta capacitat, que ha de ser planificada i tenir un seguiment al llarg del temps. A més d’això s’hi proposen dos documents que poden facilitar l’organització de la resposta educativa a aquest alumnat per part dels professionals de l’educació, atenent a les pròpies necessitats educatives, vinculades a la seua particular forma d’aprendre. Les diferents mesures proposades s’emmarquen dins del quatre nivells de mesures per afavorir la inclusió de l’alumnat que estableix la legislació vigent arran del Decret 104/2018. Un sistema educatiu que mira cap a la inclusió de tot l’alumnat s’ha d’orientar necessàriament cap a l’equitat, i no cap a la igualtat, ha de donar oportunitats a cada alumne o alumna, independentment de les seues característiques o circumstàncies.The curriculum model for gifted students continues to raise many doubts and uncertainties in the current education system. The aim of this thesis is to explain (diagnose and analyze) what is the curriculum model that currently accommodates gifted students in the Valencian education system, with the intention of developing proposals for educational improvement. The research design responds to three types of study: a documentary study, a quantitative descriptive-correlational study, and a qualitative type group discussion. The documentary study has been used to review the initial and ongoing training offered to education professionals. The correlational descriptive study analyzed the following dimensions: training received, knowledge of gifted abilities, beliefs and attitudes, knowledge of current legislation, and educational response applied to gifted students. The data were collected through two ad hoc questionnaires, one aimed at teachers and the other at professionals in educational guidance. Finally, two focus groups have been set up: one for families and the other for gifted students. The analysis of the data collected shows that the initial training of teachers and guidance professionals seems to be more focused on deficit than on the promotion of talent and to obviate the importance of working with gifted students. In addition to the lack of basic training, it is evident that many of the education professionals feel inadequately prepared to attend to gifted students. Therefore, the fact that one has received training does not guarantee that it will be transferred directly to the classroom. On the other hand, it is the youngest professionals who show the best knowledge and the least stereotypical and prejudice-free view of gifted education. In contrast, there is no significant relationship between knowledge and attitudes based on the training received. It is therefore the younger generations who are starting from a less stereotypical view of gifted education. With regard to the knowledge of the current legislation, there is a clear ignorance of the current legislation by teachers, but not in the case of guidance professionals, especially among those who work in public education and those with more years of experience in the field. Finally, in relation to the current curriculum model for gifted students in the Valencian education system, the data collected show a lack of long-term planning, coordination between stages (or even within the same stage ) and the ability to establish a clear and coherent itinerary that attends to student needs. Ultimately, the proposed intervention in this thesis addresses the need to orient the education system towards the development of student talent, and not towards the deficit, as is the case in the current education system. It is on this basis that the specific model for gifted students needs to be framed, which must be planned and monitored over time. In addition, two documents are proposed that can facilitate the organization of the curriculum model for these students by education professionals, taking into account their own educational needs, linked to their particular way of learning. The different measures proposed are framed within the four levels of measures to promote the inclusion of students established by current legislation pursuant to Decree 104/2018. An education system that looks towards the inclusion of all students must necessarily be oriented towards equity, and not towards equality, it must give opportunities to each student, regardless of their characteristics or circumstances

Activación alcalina de metacaolín. Efecto de la adición de silicato soluble y de la temperatura de curado

El objetivo del presente trabajo es determinar el efecto que la cantidad de sílice soluble presente en la disolución activadora (relación molar SiO2/Na2O entre 0 y 0.69) y la temperatura de curado (85ºC, 150ºC y 200ºC) ejercen sobre las propiedades físico-mecánicas y las características mineralógicas y microestructurales de los productos formados por activación alcalina de metacaolín. Para ello se determinaron los valores de resistencia mecánica a compresión de los materiales objeto de estudio y se realizó un estudio mineralógico y microestructural de los mismos por DRX, SEM-EDX, 29Si RMN-MAS y porosimetría de mercurio. Los resultados obtenidos muestran que la resistencia mecánica del material guarda una estrecha relación con la naturaleza, microestructura y composición química de los productos de reacción así como con las condiciones de curado. En todos los casos se genera, como principal producto de reacción, un polímero inorgánico alcalino con propiedades cementantes (gel N-A-S-H) responsable, en mayor medida, de las propiedades mecánicas del material. Como productos secundarios se forman algunas zeolitas cuya proporción y tipo (sodalita, zeolita A, faujasita, …) dependen tanto de la naturaleza del activador como de las condiciones de curado. La presencia de sílice soluble en la disolución activadora conduce a la formación de geles con una mayor relación Si/Al y a la ralentización de la zeolitización, factores, ambos, con un efecto positivo sobre la resistencia mecánica. Con respecto a la temperatura de curado, existe un valor umbral, en función de la composición del material, a partir del cual un incremento en dicha temperatura deja de tener efectos positivos sobre la evolución de la resistencia mecánicaThis study has been undertaken to determine the effect that the soluble silica content in the activating solution (molar ratio SiO2/Na2O between 0 and 0.69) and curing temperature (85ºC, 150ºC, and 200ºC) have on the physico-mechanical properties and mineralogical and microstructural characteristics of products formed by alkaline activation of metakaolin. The compression strength of the materials obtained was determined and a mineralogical and microstructural study of these materials was conducted by XRD, SEM-EDX, 29Si MAS-NMR, and mercury porosimetry. The results show that the mechanical strength of the material is closely related to the nature, microstructure, and chemical composition of the reaction products, as well as to the curing conditions. In all cases, the main reaction product that forms is an inorganic alkaline polymer with cementing properties (N-A-S-H gel), which is largely responsible for the mechanical properties of the material. Some zeolites form as by-products, whose quantity and type (sodalite, zeolite A, faujasite, etc.) depend on the nature of the activator and the curing conditions. The presence of soluble silica in the activating solution leads to the formation of gels with a larger Si/Al ratio and slower zeolitisation, these both being factors with a positive effect on mechanical strength. The curing temperature exhibits a threshold value that depends on the composition of the material, beyond which an increase in curing temperature ceases to positively affect the evolution of the material’s mechanical strengt

Use of residual diatomaceous earth as a silica source in geopolymer production

The use of binders as an alternative to Portland cement has gained importance in recent years. Among them, geopolymeric binders, developed by the reaction between an aluminosilicate precursor and a high alkalinity solution, have become one of the most promising alternatives. The activating solution generally comprises waterglass and sodium hydroxide. Since waterglass is the most expensive material and has a high environmental impact, using alternative silica sources will lead to more sustainable binders. Previous studies have successfully used rice husk ash (RHA) as a silica source. This research aims to assess the possibility of using diatomaceous earth (or diatomite) as an alternative silica source, like the previous studies with RHA. Diatomite is a sedimentary rock with a high amorphous silica content formed by fossilized diatom remains. In this work, the geopolymer was obtained using a fluid cracking catalyst residue as the precursor and six different activating solution types prepared with commercial products, residual diatomite (from beer and wine industries) and RHA. The results open a new possible route for the reuse and recovery of diatomaceous earth residue, although the compressive strength results of the mortars were slightly lower than those for mortars prepared with RHA or commercial reagents

Comparative anatomical study of standard percutaneous and modified medialised percutaneous Bunnell type repair for artificial Achilles tendon rupture: positive effect of medialisation of the stitches with lower risk of sural nerve injury

Background: Less invasive percutaneous acute Achilles tendon rupture (AATR) repair techniques gain popularity because of lower risk of surgical wound complications. But these approaches have an increased risk of sural nerve iatrogenic injury as this sensory nerve is usually not visualised during minimally invasive operative procedures. We compared standard percutaneous Bunnell type and our proposed modified-medialised percutaneous technique in a cadaver study to evaluate potential advantages. Materials and methods: Ten pairs of fresh frozen specimens were divided into two groups for comparative anatomical study. Tenotomies of Achilles tendons were made and wounds sutured. Ten standard and 10 modified-medialised repairs were applied for artificially performed ruptures. All sutured tendons were dissected meticulously. We carefully looked at repaired Achilles tendon end-to-end contact and adaptation, distance from Achilles insertion in calcaneal tubercle to place where sural nerve crosses lateral border of the Achilles tendon and possible sural nerve and vein entrapment. Groups were compared using Fisher’s exact and Student-T tests. Results: All ends of sharply dissected tendons in both groups were in sufficient contact. No measurable diastasis between tendon ends was found in all cases. No entrapment of sural nerve or vein was found in modified percutaneous Bunnell suture technique group, whereas 7 of 10 sural nerves and 9 small saphenous veins were entrapped when using standard percutaneous Bunnell type technique. Average distance from Achilles tendon insertion in tuber calcanei to sural nerve crossing the lateral border of Achilles was 93 mm. Conclusions: Medialisation of percutaneous suture in AATR repair shows clear advantages compared to standard non medialised technique ensuring a possible lower incidence of sural nerve entrapment injury. Our modified percutaneous Bunnell type technique allows sufficient adaptation of ruptured Achilles tendon.

Outstanding aspects on the use of spent FCC catalyst in binders

4 pages, 3 fiures, 7 tables.-- En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.FCC is a waste material from petrochemical plants which has interesting properties for preparing binders. FCC is lightly grey in color, and white FCC-portland cements with L*≥85 can be prepared. FCC reactivity is enhanced by grinding and it is attributed to pozzolanic reaction towards lime. Stratlingite is the main hydrated product from pozzolanic reaction, and CSH and CAH are also formed. Reactivity of FCC is high, and low curing temperature does not affect this contribution to strength in hardened mixtures. Additionally, high strength concrete can be easily prepared, and compressive strength greater 100MPa can be reached. Mixtures with low w/b ratio showed good behaviour in carbonation tests.Authors thank to Ministerio de Ciencia y Tecnología of Spain and FEDER the financial support of MAT 2001-2694 and BIA 2004-0052 projects.Peer reviewe