Resultados totales (Incluyendo duplicados): 45302
Encontrada(s) 4531 página(s)
Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283803
Dataset. 2019

DATA FROM: DATA GAPS AND OPPORTUNITIES FOR COMPARATIVE AND CONSERVATION BIOLOGY

  • Conde, Dalia A.
  • Staerk, J.
  • Colchero, F.
  • da Silva, R.
  • Schöley, J.
  • Baden, H. Maria
  • Jouvet, L.
  • Fa, John E.
  • Syed, H.
  • Jongejans, E.
  • Meiri, S.
  • Gaillard, J.M.
  • Chamberlain, S.
  • Wilcken, J.
  • Jones, O. R.
  • Dahlgren, J. P.
  • Steiner, U. K.
  • Bland, L. M.
  • Gomez-Mestre, Iván
  • Lebreton, J.D.
  • Vargas, J. G.
  • Flesness, N.
  • Canudas-Romo, V.
  • Salguero-Gómez, R.
  • Byers, O.
  • Berg, T.B.
  • Scheuerlein, A.
  • Devillard, S.
  • Schigel, Dmitry S.
  • Ryder, O.A.
  • Possingham, Hugh P.
  • Baudisch, A.
  • Vaupel, J. W.
[Usage Notes] Data This folder contains 1.) the metadatabase of 22 data sources with 115,356 standardised demographic records for 14,529 taxonomically standardised species of 10 standardised demographic variables that were used in the article, 2.) the Demographic species knowledge index (DSKI), which indicates the amount of knowledge on mortality and fertility for a total of 32,144 species, which was calculated based on the amount of information present in the “DemographicDatabase.csv” used in the article. Additionally it includes the IUCN Red List Status and if the species is present in a zoo or aquarium in ZIMS, and the species taxonomic id for Catalog of Life and GBIF. MetaData The folder contains detailed documentation of the content of the data files in the folder “Data”: 1.) the documentation of column names, 2.) the references of the 22 demographic source databases, 3.) the original demographic variable names provided in the 22 source databases before demographic standardisation, their definition, and their demographic variable name after standardisation., Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a species. Design of species conservation policies hence depends on demographic data (e.g., for extinction risk assessments or estimation of harvesting quotas). However, an overview of the accessible data, even for better known taxa, is lacking. Here, we present the Demographic Species Knowledge Index, which classifies the available information for 32,144 (97%) of extant described mammals, birds, reptiles, and amphibians. We show that only 1.3% of the tetrapod species have comprehensive information on birth and death rates. We found no demographic measures, not even crude ones such as maximum life span or typical litter/clutch size, for 65% of threatened tetrapods. More field studies are needed; however, some progress can be made by digitalizing existing knowledge, by imputing data from related species with similar life histories, and by using information from captive populations. We show that data from zoos and aquariums in the Species360 network can significantly improve knowledge for an almost eightfold gain. Assessing the landscape of limited demographic knowledge is essential to prioritize ways to fill data gaps. Such information is urgently needed to implement management strategies to conserve at-risk taxa and to discover new unifying concepts and evolutionary relationships across thousands of tetrapod species., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283897
Dataset. 2019

DATA FROM: EVIDENCE FOR LOCALLY ADAPTIVE METABOLIC RATES AMONG ANT POPULATIONS ALONG AN ELEVATION GRADIENT

  • Shik, Jonathan Zvi
  • Arnan, Xavier
  • Oms, Cristela S.
  • Cerdá, Xim
  • Boulay, Raphaël
[Usage Notes] Metabolic data Body mass and metabolic rate (MR) data of A. iberica ants from different elevations collected for this study. Units are as follows: elevation (m.a.s.l.), Temp TRT (15, 20, 25, 30, 32 C), Temperature (empirically measured temperature values C), Wet mass and Dry mass (mg), MR ((CO2 µL-1 hr-1), Mass-spec MR (mass-specific MR; CO2 µL-1 mg-1 hr-1, where mg is in dry mass). Dryad_JAE_data.xlsx, 1. As global temperatures rise, the mechanistic links between temperature, physiology and behavior will increasingly define predictions of ecological change. However, for many taxa, we currently lack consensus about how thermal performance traits vary within and across populations, and whether and how locally adaptive trait plasticity can buffer warming effects. 2. The metabolic cold adaptation hypothesis posits that cold environments (e.g. high elevations and latitudes) select for high metabolic rates (MR), even after controlling for body size differences, and that this enables high activity levels when an organism is near its cold lower thermal limits. Steep MR reaction norms are further predicted at cold temperatures to enable rapid behavioral activation with rising temperatures needed to exploit brief thermal windows suitable for performing eco-evolutionary tasks. 3. We tested these predictions by performing common garden experiments comparing thermal reaction norms of MR (from 15°C to 32°C) and behavior (from 10°C to 40°C) across populations of the ant Aphaenogaster iberica sampled from a 2 km elevation gradient in the Sierra Nevada Mountains of southern Spain. 4. As predicted, high-elevation ants had higher MR and steeper MR-temperature reaction norms. However, higher rates of energy use did not yield the predicted benefits of steeper activity-level reaction norms. 5. The evidence for locally adaptive metabolic physiology only became apparent at intermediate temperatures, highlighting the importance of testing thermal performance hypotheses across thermal gradients, rather than focusing only on performance at thermal limits (i.e. critical thermal values) 6. The partial support for the metabolic cold adaptation hypothesis highlights that while organisms likely show a wealth of unexplored metabolic temperature plasticity, the physiological mechanisms and eco-evolutionary tradeoffs underlying such local adaptation remain obscure., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283912
Dataset. 2019

DATA FROM: OUT OF THE ORIENT: POST-TETHYAN TRANSOCEANIC AND TRANS-ARABIAN ROUTES FOSTERED THE SPREAD OF BAORINI SKIPPERS IN THE AFROTROPICS

  • Toussaint, Emmanuel F. A.
  • Vila, Roger
  • Yago, Masaya
  • Chiba, Hideyuki
  • Warren, Andrew D.
  • Aduse-Poku, Kwaku
  • Storer, Caroline
  • Dexter, Kelly M.
  • Maruyama, Kiyoshi
  • Lohman, David J.
  • Kawahara, Akito Y.
[Usage Notes] Full molecular matrix Molecular matrix used for phylogenetic and dating inferences with partitioning and model selection for the BEAST analyses based on PartitionFinder results BAORINI.nex Chronogram used for biogeographic analyses Chrono.tre BEAST MCC chronogram BEAST MCC chronogram of the best analysis based on MLE comparison among all BEAST analyses (2 clocks and Yule Tree model) BAORINI_Yule_2C.tre Best IQ-TREE ML tree based on the full dataset Best ML tree based on likelihood comparison of 100 tree searches in IQ-TREE using the full dataset (AHE and available sequence data) BAO_72.treefile.tre Partitioning file for IQ-TREE analyses based on the full dataset File comprising the best partitioning scheme and models of nucleotide substitution estimated in IQ-TREE using ModelFinder across all available models for the full dataset (AHE and available sequence data) Partitions.txt.best_scheme.nex Partitioning file for IQ-TREE analyses based on the AHE dataset File comprising the best partitioning scheme and models of nucleotide substitution estimated in IQ-TREE using ModelFinder across all available models for the AHE dataset (no available sequence data) Partitions.txt.best_scheme.nex Best IQ-TREE ML tree based on the AHE dataset Best ML tree based on likelihood comparison of 100 tree searches in IQ-TREE using the full dataset (AHE and available sequence data) BAO_93.treefile.tre AHE molecular dataset Molecular matrix used for phylogenetic and dating inferences with partitioning and model selection for the BEAST analyses based on PartitionFinder results, The origin of taxa presenting a disjunct distribution between Africa and Asia has puzzled biogeographers for more than a century. This biogeographic pattern has been hypothesized to be the result of transoceanic long‐distance dispersal, Oligocene dispersal through forested corridors, Miocene dispersal through the Arabian Peninsula or passive dispersal on the rifting Indian plate. However, it has often been difficult to pinpoint the mechanisms at play. We investigate biotic exchange between the Afrotropics and the Oriental region during the Cenozoic, a period in which geological changes altered landmass connectivity. We use Baorini skippers (Lepidoptera, Hesperiidae) as a model, a widespread clade of butterflies in the Old World tropics with a disjunct distribution between the Afrotropics and the Oriental region. We use anchored phylogenomics to infer a robust evolutionary tree for Baorini skippers and estimate divergence times and ancestral ranges to test biogeographic hypotheses. Our phylogenomic tree recovers strongly supported relationships for Baorini skippers and clarifies the systematics of the tribe. Dating analyses suggest that these butterflies originated in the Oriental region, Greater Sunda Islands, and the Philippines in the early Miocene c. 23 Ma. Baorini skippers dispersed from the Oriental region towards Africa at least five times in the past 20 Ma. These butterflies colonized the Afrotropics primarily through trans‐Arabian geodispersal after the closure of the Tethyan seaway in the mid‐Miocene. Range expansion from the Oriental region towards the African continent probably occurred via the Gomphotherium land bridge through the Arabian Peninsula. Alternative scenarios invoking long‐distance dispersal and vicariance are not supported. The Miocene climate change and biome shift from forested areas to grasslands possibly facilitated geodispersal in this clade of butterflies., National Science Foundation, Award: DEB-1541500., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283916
Dataset. 2019

DATA FROM: A GLOBAL SYNTHESIS OF FIRE EFFECTS ON POLLINATORS

  • Carbone, Lucas M.
  • Tavella, Julia
  • Pausas, J. G.
  • Aguilar, Ramiro
[Usage Notes] Table S4 References and effect sizes extracted from studies analysing effect of fire on pollinator abundance. Vd = variance of Hedges’ d. In pollinator taxa column, “insect” indicates several orders. Biome abbreviations are indicated in Fig. S5 legend. Table S5 References and effect sizes extracted from studies analysing effect of fire on pollinator richness. Vd = variance of Hedges’ d. In pollinator taxa column, “insect” indicates several orders. Biome abbreviations are indicated in Fig. S5 legend., Aim: Understanding fire effects on pollinators is critical in the context of fire regime changes and the global pollination crisis. Through a systematic and quantitative review of the literature we provide the first global assessment of pollinator responses to fire. We hypothesize that pollinators increase after fire and during the early postfire succession stages; however, high fire frequency has the opposite effect, decreasing pollinators. Location: Terrestrial ecosystems, excluding Antarctica. Time period: Data collected from 1973 to 2017. Major taxa studied: Insects (Coleoptera, Diptera, Hymenoptera and Lepidoptera) and a few bird species. Methods: We first compiled available studies across the globe that assessed fire effects on pollinator communities. Then, by means of hierarchical meta-analyses, we evaluated how different fire regime parameters (fire frequency, postfire time and fire type) and habitat characteristics affect the abundance and richness of animals that act as pollinators. We also explored to what extent the responses vary among taxa groups and life history traits of pollinators (sociality system, nest location and feeding specialization), and among biomes. Results: The overall effect size of fire on pollinator abundance and richness across all studies was positive. Fire effect was especially clear and significant in early postfire communities, after wildfires, and for Hymenoptera. Taxonomic resolution influenced fire effects, where only studies at the species/genus and families levels showed significant effects. The main exceptions were recurrent fires that showed a negative effect, and especially wildfire effects on Lepidoptera abundance that showed a significant negative response. Main conclusions: Pollinators tend to be promoted after a wildfire event. However, short fire intervals may threat pollinators, and especially lepidopterans. Given the current fire regime changes at the global scale, it is imperative to monitor postfire pollinators across many ecosystems, as our results suggest that fire regime is critical in determining the dynamics of pollinator communities., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283919
Dataset. 2019

DATA FROM: LITTER MOVEMENT PATHWAYS ACROSS TERRESTRIAL-AQUATIC ECOSYSTEM BOUNDARIES AFFECT LITTER COLONIZATION AND DECOMPOSITION IN STREAMS

  • Abelho, Manuela
  • Descals, Enrique
[Usage Notes] Measurements of litter dry mass remaining, fungal and invertebrate colonization Data collected in the field dataset.ods, 1. Streams and their riparian zones are connected by spatial flows of organic matter, and constitute a model example of a meta-ecosystem. Fluxes of leaf litter from the riparian zone to the stream are a major energy source in stream food webs. Leaf litter can enter the stream vertically, falling from the tree and into the stream, or laterally, washing into the stream after a period of exposure in the terrestrial ecosystem. The latter can contribute up to 23% to the total amount of litterfall entering streams. 2. To determine if decomposition, microbial and invertebrate colonization of lateral litter inputs are similar to those of vertical inputs, we assessed leaf decomposition of alder, poplar and a 1:1 mixture of the two species in three scenarios across a gradient of terrestrial:aquatic exposures. 3. Overall decomposition was explained by a negative exponential model and decreased with the increase in the period of terrestrial exposure in all cases. Invertebrate colonization tended to decrease with the increase in the period of terrestrial exposure, but total invertebrate richness and biomass were more affected by litter type than by the exposure scenario, attaining higher values in the mixture than in the species alone. 4. As the length of exposure in the terrestrial ecosystem increased, in-stream decomposition rates of leaf litter decreased. Comparing leaf species treatments, alder decomposition rates were faster than poplar and the alder-poplar mixture. 5. The richness of the aquatic hyphomycete community colonizing leaf litter after submergence decreased and sporulation rates were strongly inhibited with an increasing terrestrial exposure period. While fungi colonizing leaf litter exposed only in the stream invested in rapid reproduction, fungi colonizing litter with prior terrestrial exposure built up more biomass. 6. We conclude that the path taken by the litter fluxes has important effects on the functioning of the receiving ecosystem. Studies relying only on the fate of freshly abscissed leaf litter (vertical inputs) may not present a complete picture of the decomposition process in streams and may have been overestimating the overall richness and reproductive activity of the aquatic hyphomycetes colonizing leaf litter., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283926
Dataset. 2019

DATA FROM: USING PLANT FUNCTIONAL DISTANCES TO SELECT SPECIES FOR RESTORATION OF MINING SITES

  • Navarro-Cano, J. A.
  • Goberna, M.
  • Verdú, Miguel
[Usage Notes] Navarro-Cano_et_al2019_dryad Sheet <>: Data of seedling emergence of 10 sowed species beneath 5 different nurse plants in a metal mine tailing in SE Spain.Sheet <>: Functional distance between pairs of nurse-sowed species. Navarro-Cano_et_al2019a_dryad Facilitated plant species and their abundances in patches and adjacent gaps in metal mine tailings from SE Spain, 1. Plant facilitation, an ecological interaction that benefits at least one species without harming the other, is increasingly used as a restoration tool. To restore degraded habitats under a facilitation framework, practitioners must correctly select both the benefactor (nurse) and the beneficiary (facilitated) species. 2. Based on community assembly and species coexistence theory, we propose selecting plant species that largely differ in a suite of functional traits so that competition is minimized and facilitation maximized due to functional complementarity. To apply this guideline in a pilot restoration experiment performed in metalliferous mine tailings in South-Eastern Spain, we first built the plant-plant facilitative interaction network naturally occurring in a set of 12 tailings. After characterizing each species with 20 morphological and physiological traits, we verified that facilitative interactions were predominantly established between functionally distant species. 3. Then, we designed a sowing experiment combining 50 nurse-facilitated species pairs separated by a wide range of functional distances. The success of seedling establishment significantly increased with the functional distance between the nurse and the facilitated plant species. 4. Synthesis and applications. We encourage to use ecological facilitation together with trait-based species selection to design restoration programmes based on the principle of increasing functional distance between target species. This method may not only promote the restoration of the plant cover but also impact paramount ecosystem functions, thus being an efficient low cost restoration practice in abiotically stressful ecosystems., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/283938
Dataset. 2019

DATA FROM: A KEY METABOLIC GENE FOR RECURRENT FRESHWATER COLONIZATION AND RADIATION IN FISHES

  • Ishikawa, Asano
  • Kabeya, Naoki
  • Ikeya, Koki
  • Kakioka, Ryo
  • Cech, Jennifer N.
  • Osada, Naoki
  • Leal, Miguel C.
  • Inoue, Jun
  • Kume, Manabu
  • Toyoda, Atsushi
  • Tezuka, Ayumi
  • Nagano, Atsushi J.
  • Yamasaki, Yo Y.
  • Suzuki, Yuto
  • Kokita, Tomoyuki
  • Takahashi, Hiroshi
  • Lucek, Kay
  • Marques, David
  • Takehana, Yusuke
  • Naruse, Kiyoshi
  • Mori, Seiichi
  • Monroig, Óscar
  • Ladd, Nemiah
  • Schubert, Carsten J.
  • Matthews, Blake
  • Peichel, Catherine L.
  • Seehausen, Ole
  • Yoshizaki, Goro
  • Kitano, Jun
[Usage Notes] DHA meta-analysis data Percentage of DHA in total fatty acid were obtained from literatures. DHA contents in algae and consumers from marine and freshwater habitats were analyzed. DHA.csv, Colonization of new ecological niches has triggered large adaptive radiations. Although some lineages have made use of such opportunities, not all do so. The factors causing this variation among lineages are largely unknown. Here, we show that deficiency in docosahexaenoic acid (DHA), an essential ω-3 fatty acid, can constrain freshwater colonization by marine fishes. Our genomic analyses revealed multiple independent duplications of the fatty acid desaturase gene Fads2 in stickleback lineages that subsequently colonized and radiated in freshwater habitats, but not in close relatives that failed to colonize. Transgenic manipulation of Fads2 in marine stickleback increased their ability to synthesize DHA and survive on DHA-deficient diets. Multiple freshwater ray-finned fishes also show a convergent increase in Fads2 copies, indicating its key role in freshwater colonization., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284006
Dataset. 2019

DATA FROM: CONFLICTING SELECTION ON CNEORUM TRICOCCON (RUTACEAE) SEED SIZE CAUSED BY NATIVE AND ALIEN SEED DISPERSERS

  • Traveset, Anna
  • Escribano-Ávila, Gema
  • Gómez, José María
  • Valido, Alfredo
[Usage Notes] DATA_CNEORUM_seed_size_CONTROL_PLANT_ID_climate_vars This file contains the data on seed diameter of Cneorum tricoccon for all the study populations, considering only seeds collected directly from plants (i.e, undispersed seeds). Data on mean anual precipitation and temperature are given. We indicate the different species of disperser present in each population, with an extra-column showing if the disperser is native (in the case of lizards) or exotic (in the case of pine-martens). This is the file we have used to test for differences in seed size among populations and to assess whether this variable is affected by climatic variables. DATA_CNEORUM_seed_size_all_disp_climate_vars This file contains data on seed diameter of Cneorum tricoccon from the different treatments (controls vs defecated/dispersed by each of the three different species: pine martens or either of the two lizards, Podarcis lilfordi or Podarcis pityusensis). In another column we code the treatment as 0 or 1 (indicating control and defecated seeds, respectively). This is the data file used for the seed selection analyses. We also include data on the climatic variables obtained for each population (mean anual precipitation and temperature). DATA_CNEORUM_GERMINATION This file contains data on the germination of seeds of Cneorum tricoccon from the different treatments (control vs dispersed by any of the three species) in each population. Data are given for each separate seed, indicating whether the seed germinated (1) or not (0). Weight (g) of each seed is given in the last column., The disappearance of native seed dispersers due to anthropogenic activities is often accompanied by the introduction of alien species, which may to some extent replace the ecological service provided by the extinct ones. Yet, little empirical evidence exists demonstrating the evolutionary consequences of such alien ‘replacement’. Here, we document the conflicting selection exerted on seed size by two native lizards (Podarcis lilfordi and P. pityusensis) and an alien mammal species (Martes martes), all acting as legitimate seed dispersers of the Mediterranean relict Cneorum tricoccon. While lizards mostly exerted a negative directional selection on seed diameter, especially P. pityusensis, the much larger pine marten exerted positive selection on seed size. Our findings suggest that this among-disperser variation in the selection regimes, together with the occurrence of spatial variation in the presence of each of seed disperser, help to create the geographical variation observed for seed size of C. tricoccon. To our knowledge, this is the first empirical evidence showing opposing selective pressures between native and alien species in the seed dispersal process in an invaded ecosystem., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284046
Dataset. 2019

CLIMATE DRIVES COMMUNITY-WIDE DIVERGENCE WITHIN SPECIES OVER A LIMITED SPATIAL SCALE: EVIDENCE FROM AN OCEANIC ISLAND

  • Salces-Castellano, Antonia
  • Patiño, Jairo
  • Álvarez, Nadir
  • Andújar, Carmelo
  • Arribas, Paula
  • Braojos-Ruiz, Juan José
  • Arco-Aguilar, Marcelino del
  • García-Olivares, Víctor
  • Karger, Dirk N.
  • López, Heriberto
  • Manolopoulou, Ioanna
  • Oromí, Pedro
  • Pérez-Delgado, Antonio
  • Peterman, William E.
  • Rijsdijk, Kenneth F.
  • Emerson, Brent C.
[Usage Notes] This files contains all DNA and topoclimate data from the manuscript. The file README contains additional data for each individual., Geographic isolation substantially contributes to species endemism on oceanic islands when speciation involves the colonisation of a new island. However, less is understood about the drivers of speciation within islands. What is lacking is a general understanding of the geographic scale of gene flow limitation within islands, and thus the geographic scale and drivers of geographical speciation within insular contexts. Using a community of beetle species, we show that when dispersal ability and climate tolerance are restricted, microclimatic variation over distances of only a few kilometres can maintain strong geographic isolation and drive incipient speciation. Further to this, we demonstrate congruent diversification with gene flow across species, mediated by Quaternary climate oscillations that have facilitated a dynamic of isolation and secondary contact. The unprecedented scale of parallel species responses to a common environmental driver for evolutionary change has profound consequences for understanding past and future species responses to climate variation., Peer reviewed

Proyecto: //

Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284054
Dataset. 2022

DATASET OF MECHANICALLY STIMULATED GAS EMISSION FROM PELLETS OF SODIUM ALANATE SUBJECTED TO RUBBING AT ROOM TEMPERATURE UNDER VACUUM AND RELATED SURFACE, STRUCTURAL, MECHANICAL, AND TRIBOLOGICAL CHARACTERIZATION OF THE PELLETS

  • Muñoz-Cortés, Esmeralda
  • Ibryaeva, Olga
  • Manso Silván, Miguel
  • Zabala, Borja
  • Flores, Eduardo
  • Gutiérrez, Almudena
  • Ares, José R.
  • Nevshupa, Roman
The pellets were subjected to reciprocating rubbing under vacuum (10-7 mbar range) using an alumina sphere, 3 mm in diameter. A specially designed friction cell with nearly zero own gas emission was used. The motion frequency was 1 Hz. One motion cycle consisted of one forth and one back stroke, each of which lasted for about 40 ms. The indenter stood still for around 50 ms after the forth stroke and 870 ms after the back one. The stroke length was la = 7 mm, the mean sliding speed was Vs = 0.18 m s-1 and the normal load was in the range 0.22 – 0.88 N. The total and partial gas pressures were measured in the experimental vacuum chamber, where the pellets were rubbed, using an ionization Bayard-Alpert type vacuum gauge and a quadrupole mass-spectrometer, correspondingly. To quantify minute gas emission rates (<1 nmol/s) the experimental chamber was connected to a gas-expansion chamber through a diaphragm, which conductance under molecular gas flow was carefully measured. Before starting the experiments, the chamber was pumped out for at least 48 hours to achieve stable background pressure (the rate of change of low-pass filtered pressure signal ≤10-11 mbar s-1). The gas emission was evaluated from the pressure time series during the mechanical action and benchmarked against the stable background. The gas composition and the emission rates were determined using a previously developed statistical matrix method. X-ray diffraction (XRD) with Cu Kα (λ = 0.15418 nm) radiation was employed for the structural characterization of NaAlH4. To assess the thermal stability of NaAlH4 Temperature-Programmed Desorption Mass-Spectrometry (TPD-MS) was used. A portion of NaAlH4 powder was placed into an alumina crucible in a glove box under Ar atmosphere (MBraun, <1 ppm H2O, <10 ppm O2). Alumina crucible was used instead of a Pt one to avoid possible decomposition of NaAlH4 due to the catalytic effect of Pt. The crucible was transferred to the TPD-MS system, where it was set into another Pt crucible. During the transfer, the sample was briefly exposed to the atmospheric air (about 5 min). The test was carried out under an Ar flux of 50 ml/s and a heating rate of 5 ºC/min. The mechanically affected zones were characterized using FTIR spectrometry, Raman confocal spectroscopy (incident laser wavelength  = 532 nm and power 5.6 mW) and Scanning Electron Microscopy (Hitachi S 800) to contrast possible structural and chemical variations induced in the material by the mechanical action. All the results were benchmarked against the measurements on the pristine zones of the same pellets., Datasets of mass-spectrometry signals were obtained in the experiments with non-thermal dehydrogenation of sodium alanate through the application of mechanical energy. An application of mechanical energy was explored as a new non-thermal method to drive H2 emission from undoped sodium alanate at room temperature. Dehydrogenation reactions were studied on a micrometer scale using localized rubbing under ultrahigh vacuum. Mechanically Stimulated Gas Emission Mass-Spectrometry (MSGE-MS) including the Dynamic gas expansion method was used to determine the kinetic parameters of hydrogen emission as well as the composition and emission behaviour of trace gases. It was found that mild rubbing of NaAlH4 pellets under vacuum led to intensive and almost instantaneous gas emission. The dominating species in the emitted gases was H2 (>99%). Traces (~0.1%) of mono- and polyalanes, NaAlH4 vapours, CO2 and other no identified gases were registered. Several H2 emission modes, which characteristic time constants ranged widely from 0.6 to 465 s, were observed. None of the dehydrogenation reactions involved could be connected to either the thermal effect of friction or the direct coupling of mechanical forces to the energy landscape of chemical reactions. The study was complemented by structural, morphological, tribological, mechanical and surface analyses. It was suggested that the tribochemical reactions can be triggered by plastic deformation and shearing., This study was co-funded by Spanish Ministry for Science and Innovation (grants PID2019-111063RB-I00, PID2020-112770RB-C22 and RTI2018-099794-B-I00) and the Basque Government via the EMAITEK Plus 2020 programme., 1.Dataset of mass-spectrometry time series of mechanically stimulated gas emission from sodium alanate (NaAlH4) pellets under vacuum.-- 2. Dataset of Thermal Programmed Desorption – Mass-Spectrometry (TPD-MS) analysis of sodium alanate.-- 3. Dataset of X-ray diffraction of sodium alanate.-- 4. Dataset of micro-FTIR spectra of pristine and mechanically activated surfaces of pellets of sodium alanate.-- 5. Dataset of Raman spectra measured on the surfaces of pellets of sodium alanate., No

DOI: http://hdl.handle.net/10261/284054, https://doi.org/10.20350/digitalCSIC/14811
Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284054
HANDLE: http://hdl.handle.net/10261/284054, https://doi.org/10.20350/digitalCSIC/14811
Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284054
PMID: http://hdl.handle.net/10261/284054, https://doi.org/10.20350/digitalCSIC/14811
Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284054
Ver en: http://hdl.handle.net/10261/284054, https://doi.org/10.20350/digitalCSIC/14811
Digital.CSIC. Repositorio Institucional del CSIC
oai:digital.csic.es:10261/284054

Buscador avanzado