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

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

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

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

Oxidation behaviour of tungsten with vanadium additions

The effect of vanadium additions on the oxidation behaviour of tungsten has been evaluated at 600 °C in dry air. Mass gain in V-containing tungsten alloys is practically the same than that of pure tungsten processed by a conventional route. The advantage of vanadium alloying arises from the suppression of periodical microcracking described during the oxidation of pure tungsten, although the scale developed during the initial stages is very porous and it is not an effective barrier for inward oxygen ingress. Further protection is conferred when an outermost dense WO3 layer is formed at the air/scale interface by condensation of volatile W and V oxides, turning the kinetics from linear to parabolic

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

Cluster Analysis of Variations in the Diurnal Pattern of Grass Pollen Concentrations in Northern Europe (Copenhagen) and Southern Europe (Córdoba)

From an allergological point of view, Poaceae pollen is one of the most important type of pollen that the population is exposed to in the ambient environment. There are several studies on intra diurnal patterns in grass pollen concentrations, and agreement on the high variability. However, the method for analysing the different patterns is not yet well established. The aim of the present study is therefore to examine the method of pattern analysis by statistical clustering, as well as relating the proposed patterns to time of season and meteorological variables at two highly different biogeographical locations; Córdoba, Spain and Copenhagen, Denmark. Airborne pollen is collected by Hirst type volumetric spore traps and counted using an optical microscope at both sites. The counts were converted to two-hours concentrations and a new method based on cluster analysis was applied with the aim of determining the most frequent diurnal patterns in pollen concentrations and their dependencies of site, season and meteorological variables. Three different well defined diurnal patterns were identified at both locations. The most frequent pattern in Copenhagen was associated with days having peak pollen concentrations in the evening (maximum between18h-20h), whereas the most frequent pattern at Córdoba was associated with days having peak pollen concentrations in the afternoon (maximum between 14h-16h). These three patterns account for 70% of days with no rain and pollen concentrations above 20 grains m-3. The most frequent pattern accounts for 40% and 57% of the days in Córdoba and Copenhagen respectively. The analysis clearly shows the great variation in pollen concentration pattern, albeit a dominating pattern can be found. It was not possible to explain all the differences in the patterns by the meteorological variables when examined individual. Clustering method is estimated to be an appropriate methodology for studying aerobiological phenomena with high variability