Dinámica del polen de la Familia Amaranthaceae en la atmósfera de la ciudad de Córdoba

XV lnternational A.P.L.E. Symposium of Palynolog

On the oxidation mechanism of pure tungsten in the temperature range 600-800 ºC

The oxidation behavior of International Thermonuclear Experimental Reactor (ITER)-reference tungsten grade has been evaluated in dry air in the temperature range 600-800 °C. At 600 °C , the scale remained protective while the integrity of W₁₈O₄₉ layer was kept. Rapid increase in mass gain resulted from massive cracking at local areas in the W₁₈O₄₉ layer. Then, a coarse non-protective columnar WO₂.₉₂ scale was developed which favoured rapid inward oxygen transport into the alloy. At 700 and 800 °C, growth stresses in the scale were released through local cracking. At this stage, WO₂.₉₂ became progressively transformed into WO₃ when the oxygen partial pressure increased across the scale thickness.This investigation was supported by the Spanish Ministry of Science and Innovation (ENE2008 06,403 C06 04). The financial support from the Comunidad de Madrid, through the program TECHNOFUSION, Grant S2009/ENE 1679

Microhabitat selection in the common lizard: implications of biotic interactions, age, sex, local processes, and model transferability among populations.

Modeling species' habitat requirements are crucial to assess impacts of global change, for conservation efforts and to test mechanisms driving species presence. While the influence of abiotic factors has been widely examined, the importance of biotic factors and biotic interactions, and the potential implications of local processes are not well understood. Testing their importance requires additional knowledge and analyses at local habitat scale. Here, we recorded the locations of species presence at the microhabitat scale and measured abiotic and biotic parameters in three different common lizard (Zootoca vivipara) populations using a standardized sampling protocol. Thereafter, space use models and cross-evaluations among populations were run to infer local processes and estimate the importance of biotic parameters, biotic interactions, sex, and age. Biotic parameters explained more variation than abiotic parameters, and intraspecific interactions significantly predicted the spatial distribution. Significant differences among populations in the relationship between abiotic parameters and lizard distribution, and the greater model transferability within populations than between populations are in line with effects predicted by local adaptation and/or phenotypic plasticity. These results underline the importance of including biotic parameters and biotic interactions in space use models at the population level. There were significant differences in space use between sexes, and between adults and yearlings, the latter showing no association with the measured parameters. Consequently, predictive habitat models at the population level taking into account different sexes and age classes are required to understand a specie's ecological requirements and to allow for precise conservation strategies. Our study therefore stresses that future predictive habitat models at the population level and their transferability should take these parameters into account

Contenido polínico de la familia Pinaceae en la atmósfera de Córdoba, España

XV lnternational A.P.L.E. Symposium of Palynolog

Influence of processing route and yttria additions on the oxidation behavior of tungsten

This study is for: The Fifteenth International Conference on Fusion Reactor Materials (ICFRM-15) was held October 16–22, 2011, at the Charleston Marriott Hotel in Charleston, South Carolina (American United States).The oxidation resistance in dry air of pure tungsten and tungsten reinforced with a dispersion of 0.6 wt.% Y₂O₃ nanoparticles has been evaluated between 873 and 1073 K, temperature range that divertor in fusion power plants should endure during long-term times in the case of loss of coolant accident and/or air ingress in the vessel. Both materials were prepared by a powder metallurgy route involving hot isostatic pressing of ball milled tungsten powders and tungsten with dispersed Y₂O₃ nanoparticles. The results have been compared with those of pure tungsten processed by conventional techniques. Thermogravimetric tests at 873 K revealed that the processing route as well as yttria addition considerably affected the oxidation resistance of pure tungsten. Mass gain of W-0.6Y₂O₃ at 873 K was five and two times lower than that of pure tungsten prepared by conventional processing techniques and by powder metallurgy, respectively. This different behavior was related to changes in the structure and composition of the oxide scale. Above 873 K, the kinetics were significantly accelerated for all materials due to the development of a non-protective oxide scale from the earliest oxidation stages, although the kinetics of Y₂O₃-containing material were still the slowest, specially at 973 K. It was analyzed how yttria additions modify the oxidation mechanism of tungsten.Consejería de Educación de la Comunidad de Madrid through the program ESTRUMAT-CM S2009MAT-1585 and by the Ministerio de Innovación y Ciencia (Project ENE2008-06403-C06-04). The additional subvention from EURATOM/CIEMAT association through contract EFDA WP11-MAT-WWALLOY.Publicad

Influence of yttria additions on the oxidation behaviour of titanium prepared by powder metallurgy

The yttria dispersion effect on the oxidation resistance of titanium prepared by powder metallurgy has been evaluated between 700 and 900º C. Yttria additions slightly increase the oxidation rate up to 800ºC and decrease it considerably at 900º C. The multilayered rutile scale formed on pure titanium prepared by conventional techniques is replaced by a denser rutile scale in the case of Titanium prepared by powder metallurgy. Yttria additions raise the temperature at which a more protective dense rutile scale is formedThis work was supported by the Dirección General de Investigación (Ministerio de Ciencia e Innovación of Spain) under grant MAT2006-13005-C03-02, and the Dirección General de Universidades (Comunidad de Madrid) through the program ESTRUMAT-CM (Grant S-0505/MAT/0077).Publicad

Tree genetic resources at risk in South America: A spatial threat assessment to prioritize populations for conservation

Background Humans threat the populations of tree species by overexploitation, deforestation, land use change, and climate change. We present a novel threat assessment at intraspecific level to support the conservation of genetic resources of 80 socioeconomically viable tree species in South America. In this assessment, we evaluate the threat status of Ecogeographic Range Segments (ERSs). ERSs are groups of populations of a specific species in a certain ecological zone of a particular grid cell of a species’ geographic occupancy. Methods We used species location records to determine the species distributions and species‐specific ERSs. We distinguished eight threat situations to assess the risk of extirpation of the ERSs of all 80 species. These threat situations were determined by large or little tree cover, low or high human pressure, and low or high climate change impact. Available layers of tree cover and threats were used to determine the levels of fragmentation and direct human pressure. Maxent niche modelling with two Global Circulation Models helped determining climate change impact by the 2050s. Results When all 80 species are considered, in total, 59% of the ERSs are threatened by little tree cover or high human pressure. When climate change is also considered, then 71‐73% of the ERSs are threatened. When an increased risk of extirpation of populations outside protected areas is considered, then 84–86% of the ERSs are threatened. Seven species warrant special attention because all their ERSs are threatened across their whole distribution in South America: Balfourondendron riedelianum, Cariniana legalis, Dalbergia nigra, Handroanthus pulcherrimus, Pachira quintana, Prosopis flexuosa, and Prosopis pallida. Conclusions Our results confirm the urgency to set up a regional action plan for the conservation of tree genetic resources in South America. With this threat assessment, we aim to support governments and organizations who are taking up this task