MNCN CSIC

Madrid, Spain

MNCN CSIC

Madrid, Spain
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Boronat C.,CIEMAT | Rivera T.,National Polytechnic Institute of Mexico | Garcia-Guinea J.,MNCN CSIC | Correcher V.,CIEMAT
Radiation Physics and Chemistry | Year: 2017

Luminescence emission from rare earth (REE) ions doped materials are being of interest since can be employed as scintillators, catalysts, battery and magnetic materials, etc. We herein report on the preliminary results obtained from the cathodoluminescence (CL) properties of undoped LaAlO3 (LAO) and LaAlO3: REE3+ (REE=Dy3+, Pr3+ and Eu3+) samples synthesized by a sol-gel process based on the Pechini's method with a spray-drying technique. The samples, previously characterized by means of Environmental Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis Spectrometry, display CL spectra with well-defined peaks that could specifically be associated with the LAO structure (in the range of 300–450 nm) and point defects (from 450 to 800 nm) spectral regions. The observed wavebands are as follows: (i) 480 and 570 from the Dy-doped LAO correspond respectively to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, (ii) 490–638 from the Pr-doped LAO is linked to 3P0→3H4, 1D2→3H4 transitions and (iii) 590 and 620 where the dopant Eu3+ gives rise to 5D0→7F1 and 5D0→7F2 transitions and (iv) a UV-blue broad band is associated with NBHOC in undoped LAO. Such emissions are due to the presence of the 4f electrons of rare earth ions that are shielded by the outer 5s and 5p electrons, the intra-4f emission spectra of REE that induce sharp and narrow wavebands. © 2016 Elsevier Ltd


Raggio J.,Complutense University of Madrid | Pintado A.,Complutense University of Madrid | Ascaso C.,MNCN CSIC | De La Torre R.,CSIC - National Institute of Aerospace Technology | And 4 more authors.
Astrobiology | Year: 2011

The Lithopanspermia space experiment was launched in 2007 with the European Biopan facility for a 10-day spaceflight on board a Russian Foton retrievable satellite. Lithopanspermia included for the first time the vagrant lichen species Aspicilia fruticulosa from Guadalajara steppic highlands (Central Spain), as well as other lichen species. During spaceflight, the samples were exposed to selected space conditions, that is, the space vacuum, cosmic radiation, and different spectral ranges of solar radiation (λ≥110, ≥200, ≥290, or ≥400 nm, respectively). After retrieval, the algal and fungal metabolic integrity of the samples were evaluated in terms of chlorophyll a fluorescence, ultrastructure, and CO 2 exchange rates. Whereas the space vacuum and cosmic radiation did not impair the metabolic activity of the lichens, solar electromagnetic radiation, especially in the wavelength range between 100 and 200 nm, caused reduced chlorophyll a yield fluorescence; however, there was a complete recovery after 72 h of reactivation. All samples showed positive rates of net photosynthesis and dark respiration in the gas exchange experiment. Although the ultrastructure of all flight samples showed some probable stress-induced changes (such as the presence of electron-dense bodies in cytoplasmic vacuoles and between the chloroplast thylakoids in photobiont cells as well as in cytoplasmic vacuoles of the mycobiont cells), we concluded that A. fruticulosa was capable of repairing all space-induced damage. Due to size limitations within the Lithopanspermia hardware, the possibility for replication on the sun-exposed samples was limited, and these first results on the resistance of the lichen symbiosis A. fruticulosa to space conditions and, in particular, on the spectral effectiveness of solar extraterrestrial radiation must be considered preliminary. Further testing in space and under space-simulated conditions will be required. Results of this study indicate that the quest to discern the limits of lichen symbiosis resistance to extreme environmental conditions remains open. © Copyright 2011, Mary Ann Liebert, Inc. 2011.


Fernandez-Cortes A.,MNCN CSIC | Benavente D.,University of Alicante | Cuezva S.,University of Alicante | Canaveras J.C.,University of Alicante | And 4 more authors.
Atmospheric Environment | Year: 2013

Fluctuations of trace gas activity as a response to variations in weather and microclimate conditions were monitored over a year in a shallow volcanic cave (Painted Cave, Galdar, Canary Islands, Spain). 222Rn concentration was used due to its greater sensitivity to hygrothermal variations than CO2 concentration. Radon concentration in the cave increases as effective vapour condensation within the porous system of the rock surfaces inside the cave increases due to humidity levels of more than 70%. Condensed water content in pores was assessed and linked to a reduction in the direct passage of trace gases. Fluctuations in radon activity as a response to variations in weather and microclimate conditions were statistically identified by clustering entropy changes on the radon signal and parameterised to predict radon concentration anomalies. This raises important implications for other research fields, including the surveillance of shallow volcanic and seismic activity, preventive conservation of cultural heritage in indoor spaces, indoor air quality control and studies to improve understanding of the role of subterranean terrestrial ecosystems as reservoirs and/or temporary sources of trace gases. © 2013 Elsevier Ltd.


Yanez-Arenas C.,Institute Ecologia Ac | Guevara R.,Institute Ecologia Ac | Martinez-Meyer E.,National Autonomous University of Mexico | Mandujano S.,Red de Biologia y Conservacion de Vertebrados | Lobo J.M.,MNCN CSIC
Ecological Modelling | Year: 2014

Modelling geographic patterns of abundance/density of species is an important step forward in ecological niche modelling, with implications for theoretical and applied ecology. The distance to the niche centroid approach (DNC) is a methodological development toward better understanding how the internal structure of species' ecological niches is related to geographic patterns of abundance. We evaluated this approach under combinations of three sampling scenarios and three sampling intensities for a hypothetical species for which abundance patterns were ideal and strictly controlled. Our results indicate that predictive ability of the DNC approach increased with sample intensity, particularly under a strict random sampling scheme. Model performance under a sampling scenario biased by species' density fell slightly, but was importantly reduced when the source of the biases were attractor sites unrelated with species' traits. We conclude that the DNC approach is only suitable to model species' abundances/densities under particular conditions. First because it is necessary fulfill some assumptions (discussed in this paper), and second because its performance strongly depends on sampling characteristics that are unusual in most biodiversity data. © 2014 Elsevier B.V.


Garcia-Anton E.,MNCN CSIC | Cuezva S.,University of Alicante | Fernandez-Cortes A.,MNCN CSIC | Benavente D.,University of Alicante | Sanchez-Moral S.,MNCN CSIC
International Journal of Greenhouse Gas Control | Year: 2014

A multiparametric study of Altamira cave conditions was performed to identify mechanisms that affect CO2. A daily survey was used to better understand the role of the shallow vadose system as a source/sink of this gas. Airborne particles were monitored to distinguish the air movement that was joined to δ13CO2 and were also used as a proxy of the origin of the CO2. A gas transport model has been created based on the interaction of three air masses (soil-cave-exterior), which is driven by soil-derived CO2 diffusion to the cave and by the advective mixing of the cave with exterior air. The diffusive process increases cave CO2 and decreases δ13CO2. The advective mixing induces a decrease in CO2 and an increase in the isotopic signal. The diffusive flux depends on soil CO2 production; the advective flux is driven by outer-inner density gradients, and both depend on the degree of exchange between air masses. Consequently, external conditions, such as temperature and humidity, regulate gas interchange. The created process-based model permits the quantification of CO2 fluxes. The consequence of the degassing stage is the release of light CO2 (δ13C quantified in -24.82‰) into the exterior air (δ13C measured in -11.34‰). The migration of gas in the vadose zone may influence many environmental processes, and therefore, the contribution of shallow underground systems to surface CO2 exchange and to the isotopic signal of troposphere should be accounted for. © 2013.


Gonzalez-Perez J.A.,IRNAS CSIC | Jimenez-Morillo N.T.,IRNAS CSIC | de la Rosa J.M.,IRNAS CSIC | Almendros G.,MNCN CSIC | Gonzalez-Vila F.J.,IRNAS CSIC
Journal of Chromatography A | Year: 2015

Polyethylene is probably the most used plastic material in daily life and its accurate analysis is of importance. In this communication the chemical structure of polyethylenes is studied in detail using conventional analytical pyrolysis (Py-GC/MS), bulk stable isotopic analysis (IRMS) and pyrolysis compound specific stable isotopic analysis (Py-CSIA) to measure stable isotope proportions (δ13C, δ15N and δD) of polyethylene pyrolysis compounds. Polyethylene pyrolysis yields triplet peaks of n-alkanes, α-alkenes and α,ω-alkanedienes. No differences were found for bulk δ13C among different polyethylene types. However, conspicuous differences in δD were evident. It was possible to assign structure δ13C and δD values to specific polyethylene pyrolysis products in the range 12-18 carbon chain length. Conspicuous differences were found for the pyrolysis products with unsaturated moieties showing significant higher δD values than saturated chains (alkanes) that were deuterium depleted. In addition, a full isotopic fingerprinting (δ13C, δ15N and δD) for a dye (o-chloroaniline) contained in a polyethylene is reported. To the best of our knowledge this is the first application Py-CSIA to the study of a synthetic polymer. This hyphenated analytical technique is a promising tool to study synthetic materials, providing not only a fingerprinting, but also allowing the traceability of the polymerization process and the origin of the materials. © 2015 Elsevier B.V.


Gonzalez-Perez J.A.,IRNAS CSIC | Jimenez-Morillo N.T.,IRNAS CSIC | de la Rosa J.M.,IRNAS CSIC | Almendros G.,MNCN CSIC | Gonzalez-Vila F.J.,IRNAS CSIC
Journal of the Science of Food and Agriculture | Year: 2016

BACKGROUND: Pyrolysis-compound specific isotopic analysis (Py-CSIA: Py-GC-(FID)-C-IRMS) is a relatively novel technique that allows on-line quantification of stable isotope proportions in chromatographically separated products released by pyrolysis. Validation of the Py-CSIA technique is compulsory for molecular traceability in basic and applied research. In this work, commercial sucrose from C4 (sugarcane) and C3 (sugarbeet) photosystem plants and admixtures were studied using analytical pyrolysis (Py-GC/MS), bulk δ13C IRMS and δ13C Py-CSIA. RESULTS: Major pyrolysis compounds were furfural (F), furfural-5-hydroxymethyl (HMF) and levoglucosan (LV). Bulk and main pyrolysis compound δ13C (‰) values were dependent on plant origin: C3 (F, -24.65 ± 0.89; HMF, -22.07 ± 0.41‰ LV, -21.74 ± 0.17‰) and C4 (F, -14.35 ± 0.89‰ HMF, -11.22 ± 0.54‰ LV, -11.44 ± 1.26‰). Significant regressions were obtained for δ13C of bulk and pyrolysis compounds in C3 and C4 admixtures. Furfural (F) was found 13C depleted with respect to bulk and HMF and LV, indicating the incorporation of the light carbon atom in position 6 of carbohydrates in the furan ring after pyrolysis. CONCLUSION: This is the first detailed report on the δ13C signature of major pyrolytically generated carbohydrate-derived molecules. The information provided by Py-CSIA is valuable for identifying source marker compounds of use in food science/fraud detection or in environmental research. © 2015 Society of Chemical Industry © 2016 Society of Chemical Industry.


Gonzalez-Perez J.A.,IRNAS CSIC | Almendros G.,MNCN CSIC | De La Rosa J.M.,IRNAS CSIC | Gonzalez-Vila F.J.,IRNAS CSIC
Journal of Analytical and Applied Pyrolysis | Year: 2014

Large number of studies has demonstrated the usefulness of flash pyrolysis in association with GC-MS in releasing diagnostic volatile compounds informing about the complex composition of natural organic matter (NOM). This knowledge is of interest as regards monitoring agricultural and environmental processes including pollution. In this context the term NOM comprises a wide array of biomacromolecules (lignins, polysaccharides, proteins, lipid polymers, etc.), as well as complex three-dimensional macromolecules, either labile or recalcitrant, and which are referred to with generic terms such as dissolved organic matter, humic substances and black carbon. In this communication an updated overview on recent advances achieved by analytical pyrolysis in the structural characterization of recalcitrant/fossil/NOM is presented, with particular focus in the detection of polycyclic aromatic compounds (PAHs) within complex organic matrices. © 2014 Elsevier B.V.


PubMed | IRNAS CSIC and MNCN CSIC
Type: Journal Article | Journal: Journal of the science of food and agriculture | Year: 2016

Pyrolysis-compound specific isotopic analysis (Py-CSIA: Py-GC-(FID)-C-IRMS) is a relatively novel technique that allows on-line quantification of stable isotope proportions in chromatographically separated products released by pyrolysis. Validation of the Py-CSIA technique is compulsory for molecular traceability in basic and applied research. In this work, commercial sucrose from C4 (sugarcane) and C3 (sugarbeet) photosystem plants and admixtures were studied using analytical pyrolysis (Py-GC/MS), bulk (13)C IRMS and (13)C Py-CSIA.Major pyrolysis compounds were furfural (F), furfural-5-hydroxymethyl (HMF) and levoglucosan (LV). Bulk and main pyrolysis compound (13)C () values were dependent on plant origin: C3 (F, -24.65 0.89; HMF, -22.07 0.41; LV, -21.74 0.17) and C4 (F, -14.35 0.89; HMF, -11.22 0.54; LV, -11.44 1.26). Significant regressions were obtained for (13)C of bulk and pyrolysis compounds in C3 and C4 admixtures. Furfural (F) was found (13)C depleted with respect to bulk and HMF and LV, indicating the incorporation of the light carbon atom in position 6 of carbohydrates in the furan ring after pyrolysis.This is the first detailed report on the (13)C signature of major pyrolytically generated carbohydrate-derived molecules. The information provided by Py-CSIA is valuable for identifying source marker compounds of use in food science/fraud detection or in environmental research.


PubMed | IRNAS CSIC and MNCN CSIC
Type: | Journal: Journal of chromatography. A | Year: 2015

Polyethylene is probably the most used plastic material in daily life and its accurate analysis is of importance. In this communication the chemical structure of polyethylenes is studied in detail using conventional analytical pyrolysis (Py-GC/MS), bulk stable isotopic analysis (IRMS) and pyrolysis compound specific stable isotopic analysis (Py-CSIA) to measure stable isotope proportions ((13)C, (15)N and D) of polyethylene pyrolysis compounds. Polyethylene pyrolysis yields triplet peaks of n-alkanes, -alkenes and ,-alkanedienes. No differences were found for bulk (13)C among different polyethylene types. However, conspicuous differences in D were evident. It was possible to assign structure (13)C and D values to specific polyethylene pyrolysis products in the range 12-18 carbon chain length. Conspicuous differences were found for the pyrolysis products with unsaturated moieties showing significant higher D values than saturated chains (alkanes) that were deuterium depleted. In addition, a full isotopic fingerprinting ((13)C, (15)N and D) for a dye (o-chloroaniline) contained in a polyethylene is reported. To the best of our knowledge this is the first application Py-CSIA to the study of a synthetic polymer. This hyphenated analytical technique is a promising tool to study synthetic materials, providing not only a fingerprinting, but also allowing the traceability of the polymerization process and the origin of the materials.

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