Novedades para la flora briofítica española

Se da a conocer el hallazgo de Atrichum crispum (James) Sull., Dicranella staphylina Whitehouse, Ditrichum pusillum (Hedw.) Britt en Navarra, como novedades para la brioflora española. Se aporta Dicranella schreberiana (Hedw.) Hilp. ex Crum & Anders. como cita interesante. Summary: Atrichum crispum (James) Sull., Dicranella staphylina Whitehouse, Ditrichum pusillum (Hedw.) Britt are recorded as new for the Spanish bryophytic flora. Dicranella schreberiana (Hedw.) Hilp. ex Crum & Anders. is also recorded

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

Quantitative disentanglement of nanocrystalline phases in cement pastes by synchrotron ptychographic X-ray tomography

Mortars and concretes are ubiquitous materials with very complex hierarchical microstructures. To fully understand their main properties and to decrease their CO2 footprint, a sound description of their spatially resolved mineralogy is necessary. Developing this knowledge is very challenging as about half of the volume of hydrated cement is a nanocrystalline component, calcium silicate hydrate (C-S-H) gel. Furthermore, other poorly crystalline phases (e.g. iron siliceous hydrogarnet or silica oxide) may coexist, which are even more difficult to characterize. Traditional spatially resolved techniques such as electron microscopy involve complex sample preparation steps that often lead to artefacts (e.g. dehydration and microstructural changes). Here, synchrotron ptychographic tomography has been used to obtain spatially resolved information on three unaltered representative samples: neat Portland paste, Portland–calcite and Portland–fly-ash blend pastes with a spatial resolution below 100 nm in samples with a volume of up to 5 x 104 mm3. For the neat Portland paste, the ptychotomographic study gave densities of 2.11 and 2.52 g cm -3 and a content of 41.1 and 6.4 vol% for nanocrystalline C-S-H gel and poorly crystalline iron siliceous hydrogarnet, respectively. Furthermore, the spatially resolved volumetric mass-density information has allowed characterization of inner-product and outer-product C-S-H gels. The average density of the inner-product C-S-H is smaller than that of the outer product and its variability is larger. Full characterization of the pastes, including segmentation of the different components, is reported and the contents are compared with the results obtained by thermodynamic modelling.This work has been supported by MINECO through BIA2014-57658 and BIA2017-82391-R research grants, which are cofunded by FEDER. Instrumentation development was supported by SNF (R’EQUIP, No. 145056,‘OMNY’) and the Competence Centre for Materials Science and Technology (CCMX) of the ETH-Board, Switzerland

Applications of synchrotron x-ray powder diffraction in hydrated cements: high-resolution and high-pressure studies

The main aim of this study is to apply synchrotron radiation techniques for the study of hydrated cement pastes. In particular, the tetracalcium aluminoferrite phase, C4AF in cement nomenclature, is the major iron-containing phase in Ordinary Portland Cement (OPC) and in iron rich belite calcium sulfoaluminate cements. In a first study, the hydration mechanism of pure tetracalcium aluminoferrite phase with water-to-solid ratio of 1.0 has been investigated by HR-SXRPD (high resolution synchrotron X-ray powder diffraction). C4AF in the presence of water hydrates to form mainly an iron-containing hydrogarnet-type (katoite) phase, C3A0.84F0.16H6, as single crystalline phase. Its crystal structure and stoichiometry were determined by the Rietveld method and the final disagreement factors were RWP=8.1% and RF=4.8% [1]. As the iron content in the product is lower than that in C4AF, it is assumed that part of the iron also goes to an amorphous iron rich gel, like the hydrated alumina-type gel, as hydration proceeds. Further results from the high-resolution study will be discussed. In a second study, the behavior of pure and iron-containing katoites (C3AH6 and C3A0.84F0.16H6) under pressure have been analyzed by SXRPD using a diamond anvil cell (DAC) and then their bulk moduli were determined. The role of the pressure transmitting medium (PTM) has also been studied. In this case, silicone oil as well as methanol/ethanol mixtures have been used as PTM. Some “new peaks” were detected in the pattern for C3A0.84F0.16H6 as pressure increases, when using ethanol/methanol as PTM. These new peaks were still present at ambient pressure after releasing the applied pressure. They may correspond to crystalline nordstrandite or doyleite from the crystallization of amorphous aluminium hydroxide. The results from the high-pressure study will also be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Acknowledgments: We thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time. We also thank the financial support by BIA2014-57658-C2-1-R and BIA2014-57658-C2-2-R (FEDER)

In-situ hydration studies of ye’elemite at early ages for understanding eco-cement performances'

Póster; ALBA User Meeting and VI AUSE Conferenc

Efecto del fuego sobre la flora micorrícica de una formación natural de carrasca

El objetivo de este trabajo es el estudio tanto cuantitativo como cualitativo de los morfotipos de ectomicorrizas que aparecen asociados de forma natural a la carrasca, Quercus ilex L. subsp. ballota (Desf.) Samp. Este estudio se ha llevado a cabo en un carrascal de Navarra afectado en 1993 por un incendio forestal. Los muestreos se han realizado en dos zonas de dicho carrascal, una alterada por el incendio (zona quemada), y otra que no sufrió ninguna perturbación (zona control). Por una parte, se ha analizado el efecto del fuego sobre el estado micorrícico de las carrascas, comparando los porcentajes de micorrización de la zona quemada y de la zona control, y, por otra, se ha contrastado la diversidad y la abundancia de los morfotipos de ectomicorrizas que aparecen en ambas zonas, haciendo una descripción de dichos morfotipos, e identificando al hongo que los forma en la medida de lo posible. SUMMARY The aim of this study is the quantitative and qualitative analysis of the ectomycorrhizal morphotypes naturally associated with evergreen oak, Quercus ilex L. subsp. ballota (Desf.) Samp. The study has been undertaken in an evergreen oak forest located in Navarra. Part of this forest burned in 1993, but most of it remains undisturbed. Thus, samples have been taken from both the burned and the control study sites. The impact of fire on the mycorrhizal state of evergreen oaks has been analysed by comparing the percentages of mycorrhization in the burned and the control areas. On the other hand, the diversity and abundance of the ectomycorrhizal morphotypes occurring in both sites have also been studied. The ectomycorrhizal morphotypes found have been described, and the fungal partner has been identified when possible

Identificación y descripción de las Ectomicorrizas de Quercus Ilex L. Subsp. Ballota (Desf.) Samp. en una zona quemada y una zona sin alterar del carrascal de Nazar (Navarra)

Desde 1998, se ha llevado a cabo un estudio de campo en un bosque de Quercus ilex L. subsp. ballota (Desf.) Samp. situado en Nazar (Navarra, España). El objetivo de este estudio es la comparación cualitativa y cuantitativa de los tipos de ectomicorrizas que han sido descritos e identificados en una zona quemada y una zona control de este carrascal. Así, se pretende paliar la escasez de conocimiento en el tema de las ectomicorrizas asociadas con la carrasca en condiciones naturales, ya que la mayoría de los trabajos publicados están relacionados con la truficultura o la micorrización inducida en vivero

Post-fire, seasonal and annual dynamics of the ectomycorrhizal community in a Quercus ilex L. forest over a 3-year period

Two study plots, burned and control, were established in autumn 1998 in a Quercus ilex forest located in northern Spain, part of which had been affected by a low intensity fire in 1994. Soil samples for ectomycorrhizae (ECM) were taken over a 3-year period in each study plot in spring, summer, autumn and winter. ECM morphotypes were identified and the relative abundance of each morphotype in each soil sample calculated, along with species richness, Shannon diversity index and percentage of mycorrhization in each soil sample. The relative abundance of certain ECM morphotypes differed between burned and control plots, and the percentage of mycorrhizal tips was significantly lower in the burned than in the control plot. Nevertheless, there were no significant differences in the diversity, species richness or species composition of the ECM community in the burned and control plots. The dominant ECM morphotypes in both stands were Cenococcum geophilum and several thelephoroid fungi. Sphaerosporella brunnea and Pisolithus tinctorius thrived especially in the burned plot, whereas three ectomycorrhizal morphotypes assigned to the genus Hebeloma were especially abundant in the control plot. There was no significant variation in the relative abundance of the ECM morphotypes between seasons, but ECM community species richness was highest in autumn and lowest in summer. The percentage of mycorrhizal tips reached a maximum in winter, with its minimum in autumn. Collection of samples over the 3-year period also enabled us to detect a significant increase in percentage of ECM colonisation in the burned stand over time

Briófitos de Arbayún (Navarra)

Se ha estudiado la flora briofítica de la Foz de Arbayún (Navarra). Se citan 66 especies (19 hepáticas y 47 musgos), 3 de las cuales son novedad para Navarra. Summary: The bryological flora of Foz de Arbayun (Navarra) is studied. We have cited 66 species (19 liverworts and 47 mosses), 3 of them are new records for Navarra

Primeros datos sobre la reforestación de un área de carrascal quemado con plantas de Quercus ilex subsp. ballota inoculadas con Tuber melanosporum.

Se ha llevado a cabo un estudio acerca de la comunidad micorrícica de Quercus ilex L. subsp. ballota (Desf.) Samp. en un carrascal situado en Nazar (Navarra, España) afectado en parte por un incendio. En la zona quemada de este carrascal, que se encuentra dentro de la zona de distribución potencial de la trufa negra en Navarra, se ha introducido una serie de plantas de carrasca inoculadas en vivero con Tuber melanosporum Vitt. acompañadas por plantas no micorrizadas de forma artificial que actúan como control, para así analizar la permanencia del hongo inoculado y la posible competencia con otras especies ectomicorrícicas que se encuentren en el medio. A partir de los datos obtenidos en esta investigación se puede concluir que las micorrizas de Tuber melanosporum persisten al cabo de 3 años de su introducción en la zona quemada del carrascal de Nazar, aunque han de competir con otros hongos micorrícicos presentes en el ecosistema, por lo que T. melanosporum puede ser un hongo adecuado para su utilización como inóculo micorrícico de plantas de Quercus ilex subsp. ballota usadas para reforestar carrascales incendiados que se encuentren situados dentro del área de distribución potencial de la trufa negra en Navarra