281 research outputs found

    Differences in n-type doping efficiency between Al- and Ga-ZnO films

    Get PDF
    A careful and wide comparison between Al and Ga as substitutional dopants in the ZnO wurtzite structure is presented. Both cations behave as n-type dopants and their inclusion improves the optical and electrical properties of the ZnO matrix, making it more transparent in the visible range and rising up its electrical conductivity. However, the same dopant/Zn ratio leads to a very different doping efficiency when comparing Al and Ga, being the Ga cation a more effective dopant of the ZnO film. The measured differences between Al- and Ga-doped films are explained with the hypothesis that different quantities of these dopant cations are able to enter substitutionally in the ZnO matrix. Ga cations seem to behave as perfect substitutional dopants, while Al cation might occupy either substitutional or interstitial sites. Moreover, the subsequent charge balance after doping appear to be related with the formation of different intrinsic defects that depends on the dopant cation. The knowledge of the doped-ZnO films microstructure is a crucial step to optimize the deposition of transparent conducting electrodes for solar cells, displays, and other photoelectronic devices.Ministerio de Ciencia e Innovación TEC2007-60996, MAT2008-06858-C02-02, MAT2008- 06330, TEC2010-16700FUNCOAT CSD2008-00023- CONSOLIDER INGENIOSonderforschungsbereich SFB 76

    Estudio de las comunidades de interés pascícola en un puerto de montaña: II. Evolución en la intensidad de selección del pasto por dos razas ovinas (Churra y Merina)

    Get PDF
    11 páginas, 1 figura, 3 tablas.[ES] Con objeto de conocer la intensidad de selección del pasto en el ganado ovino y las diferencias entre los animales de raza Churra y de raza Merina en este parámetro, se llevo a cabo un experimento sobre un pasto de "Nardus” en la zona de montaña del Puerto de San Isidro en la provincia de León. Se utilizaron 4 machos adultos castados de cada raza, provistos de fístulas esofágicas para la toma de muestras de la dieta seleccionada por los animales (extrusa). El muestreo tuvo lugar en la última semana de los meses de junio, julio, agosto y septiembre de 1990. En cada muestra se separaron las hojas y los tallos, expresándolos posteriormente como porcentaje de la materia seca. No se encontraron diferencias estadísticamente significativas (P>0,05) entre ambas razas, en la proporción de hojas en las extrusas (88,3 vs 85,3% para las razas Churra y Merina respectivamente). El efecto del periodo fue estadisticamente significativo (P>0,01) para la proporción de hojas, con un menor valor (78%) en julio. Las diferencias entre periodos, tampoco fueron estadísticamente significativas (P>0,05) en la selección de hojas en la raza Churra, no obstante en la raza Merina se obtuvo un menor valor en la proporción de hojas en las extrusas en el segundo periodo. El índice de seleccion (% de hojas en la extrusa /% hojas en el pasto) presentó diferencias en los valores correspondientes a los distintos periodos. En la raza Merina durante los meses de junio y julio el valor del índice de selección fue significativamente menor que en los meses de agosto y septiembre, no encontrando diferencias significativas en estos pares de valores. Para la raza Churra, el valor del índice de selección obtenido en el mes de junio fue significativamente menor que el encontrado en los otros tres periodos, entre los cuales no se pudo comprobar la existencia de diferencias estadsticamente significativas.[EN] In order to know how the grazing period during summer affects to the degree of food selection in mountain areas and consistency of this differences in Churro and Merino genotypes an experiment on “Nardus” grass was carried out. Four oesophageal fistulated wether lambs of each breed were used during the last week of June, ,July, August and September 1990 and the leaf and steam were separated in each sample. There were no differences (P>0,05) between breed in the proportion of extrusa leaves (88,3 and 85,3% for Churra and Merino respectively). The effect of period was significatively different (P0,05) entre les deux races en ce qui concerne la proportion de feuilles dans les extrusas (88,3 vs 85,3% pour les races Churra et Merina respectivement). L’effet de la pèriode a été statistiquement significatif (P0,05) en ce qui concerne la sélection de feuilles chez la race Churra, cependant chez la race Merina nous avons obtenu une valeur inférieure dans la proportion de feuilles dans les extrusas pendant la second période. L’indice de sélection (% de feuilles dans l’extrusa / % de feuilles dans le pâturage) a présenté des differences dans les valeurs correspondantes aux différentes périodes. Chez la race Merina pendant les mois de juin et juillet la valeur de l’indice de sélection a été significativement infèrieure à celle des mois d’aôutet septembre, sans trouver de différences significatives dans ces deux valeurs. Pour la race Churra, la valeur de l’indice de sélection obtenue pendant le mois de juin a été significativement inférieure á celle trouvée pendant les trois autre périodes, entre les quelles nous n’avons pas pu vérifier l’existence de différences statisquement significatives.Este trabajo forma parte del proyecto titulado "Utilización de pastos de montaña por el ganado ovino", subvencionado por la Excma. Diputación de León y ha sido realizado dentro del convenio específico de colaboración entre la Excma. Diputación Provincial de León y la Estación Agrícola Experimental del CSIC.Peer reviewe

    Separación de aceitunas sobremaduras y alambradas en línea mediante rebote

    Get PDF
    La fermentación tradicional de aceitunas de mesa da lugar a la aparición de distintos tipos de defectos: alambrado, compactado y sobremaduración. En este estudio se han ensayado varios lotes que incluyen aceitunas sanas y defectuosas, caracterizándolas objetivamente por color, dureza y densidad. Se ha diseñado asimismo un dispositivo en línea consistente en un cilindro rotativo recubierto con un material amortiguador. Este elemento permite separar correctamente el 95% de las aceitunas blandas (alambradas y sobremaduras) respecto a las sanas. Las aceitunas compactas pueden separarse mediante densidad. En este artículo se presentan los resultados de un trabajo que será expuesto en el II Congreso Nacional de Agrolngeniería 2003 (Córdoba

    Multidecadal (1997-2020) telecoupling of water management for terrestrial agriculture and a marine fishery at southern Spain

    Get PDF
    Climate change is decreasing water supplies globally while water demand is rising, making water access and distribution essential for sustainability, equity, and efficiency. In response, water management has shifted towards practices that improve water efficiency. However, links between geographically separated socioecological systems, known as telecouplings, can obscure the potential consequences of water use. This study focuses on a telecoupling between terrestrial water use and marine fisheries for the period 1997 to 2020. We develop a case study in southern Spain using multidecadal time series of the Guadalquivir river’s hydrology, its estuarine community, and the European anchovy (Engraulis encrasicolus) fishery in the Gulf of Cadiz. We found that water extracted to irrigate crops decreased the river’s flow and seasonality. However, anchovies used the estuary as a nursery before recruiting to the ocean, where they were harvested. Anchovy recruitment improved when estuary hydrology matched the Guadalquivir River’s historical hydrology (i.e., high discharge and seasonality). Then using hydro-economic modeling, we explored the outcomes of different water policies on the telecoupled socioecological systems. Our models predicted that improved water efficiency incentivized agricultural expansion. In contrast, continued marine fishery yields required management values that supported the value of the marine fishery. We highlight estuaries’ critical role in driving marine systems; yet, upriver processes drive estuaries dynamics. Overall, marine-terrestrial telecouplings provide evidence that marine fisheries that rely on estuarine reliant species would benefit of water policy and management being extended beyond the water basin

    Molecular characterization of dissolved organic matter linked to microbial (Bacteria and Archaea) diversity in the main water masses of the Eastern North Atlantic Ocean

    Get PDF
    The microbe-dissolved organic matter (DOM) interactions include microbial uptake and DOM reworking and release, affecting the composition of the heterogeneous DOM pool. In turns, this distinct DOM composition can select for microbial assemblages. We investigated the diversity of microbial (both Bacteria and Archaea) communities (combining Illumina tag sequencing of 16S rRNA gen -amplicon sequencing variants, ASVs- and metagenomics) and the chemodiversity of dissolved organic molecules (extracted by solid phase extraction and analyzed by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, FT-ICR-MS) in the Eastern North Atlantic Ocean off the Galician coast (43oN, 9o-15oW). Sampling ranged from 100 m to 5000 m, thereby encompassing a wide variety of water masses with contrasting origins and different aging. Applying diversity ecological metrics to both organic compounds and ASVs, we found that microbial diversity and richness were negatively correlated with DOM concentration and chemo-diversity. Besides, our results demonstrated the link between this trend and water mass aging, which enhances biosphere taxonomic diversity but reduces molecular variety. DOM diversity, decreasing along the water mass aging gradient, would likely reflect the persistence of the most refractory molecules, generated as by- product of the DOM degradation by microbes. In two PCoAs based on the metagenomic data, combined PCoA axis 1 and PCoA axis 2, explained the 80% and 20% of the microbial gene ́s structural variability among water masses. The oldest water masses, originated at high latitudes, such as NADW and LDW, were associated to higher abundance of genes involved in metabolism of aromatic compound. Intermediate waters such as ENACWst were related to sulphur/iron/phosphorous metabolism related genes. Surface waters were linked to genes involved in photosynthesis, autotrophy and cell division. Taken together, the observed increase of DOM homogenization along water mass aging was associated to differences in the functional diversity of microbial communities

    Uncovering the deeply embedded active galactic nucleus activity in the nuclear regions of the interacting galaxy Arp 299

    Get PDF
    Alonso-Herrero, A. et al.We present mid-infrared (MIR) 8-13 μm spectroscopy of the nuclear regions of the interacting galaxy Arp 299 (IC 694+NGC 3690) obtained with CanariCam (CC) on the 10.4 m Gran Telescopio Canarias (GTC). The high angular resolution (∼0.″3-0.″6) of the data allows us to probe nuclear physical scales between 60 and 120 pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded active galactic nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC 3690/Arp 299-B1 can be explained as emission from AGN-heated dust in a clumpy torus with both a high covering factor and high extinction along the line of sight. The estimated bolometric luminosity of the AGN in NGC 3690 is 3.2 ± 0.6 × 1044 erg s-1. The nuclear GTC/CC spectrum of IC 694/Arp 299-A shows 11.3 μm polycyclic aromatic hydrocarbon emission stemming from a deeply embedded (AV ∼ 24 mag) region of less than 120 pc in size. There is also a continuum-emitting dust component. If associated with the putative AGN in IC 694, we estimate that it would be approximately five times less luminous than the AGN in NGC 3690. The presence of dual AGN activity makes Arp 299 a good example to study such phenomena in the early coalescence phase of interacting galaxies. © 2013. The American Astronomical Society. All rights reserved.The following Spanish Plan Nacional de Astronomía y Astrofísica grants are acknowledged: AYA2009-05705-E (A.A.H., P.E., C.R.A., and M.P.S.), AYA2010-21887-C04 (C.R.A. and J.M.R.E.), AYA2010-18029 (A.A.R.), AYA2010-21161-C02-01 (L.C.), and AYA2012-39168-C03-01 (J.M.R.E. and O.G.M.). A.A.R. also acknowledges financial support through the Ramón y Cajal fellowships and Consolider-Ingenio 2010 CSD2009-00038. C.P. and C.M.T. acknowledge support from NSF grants 0904421 and AST-903672, respectively.Peer Reviewe

    RITA: a 1U multi-sensor Earth observation payload for the AlainSat-1

    Get PDF
    The Remote sensing and Interference detector with radiomeTry and vegetation Analysis (RITA) is one of the Remote Sensing payloads selected as winners of the 2nd GRSS Student Grand Challenge in 2019, to fly on board of the 3U AlainSat-1. This CubeSat is being developed by the National Space Science and Technology Center (NSSTC), United Arab Emirates University. RITA has been designed as an academic mission, which brings together students from different backgrounds in a joint effort to apply very distinct sensors in an Earth Observation mission, fusing their results to obtain higher-accuracy measurements. The main payload used in RITA is a Total Power Radiometer such as the one on board the FSSCat mission. With these radiometric measurements, soil moisture and ice thickness will be obtained. To better characterize the extensive Radio-Frequency Interferences received by EO satellites in protected bands, several RFI Detection and Classification algorithms will be included to generate a worldwide map of RFI. As a novel addition to the 3Cat family of satellites and payloads, a hyper-spectral camera with 25 bands ranging from 600 to 975 nm will be used to obtain several indexes related to vegetation. By linking these measurements with the soil moisture obtained from the MWR, pixel downscaling can be attempted. Finally, a custom- developed LoRa transceiver will be included to provide a multi-level approach to in-situ sensors: On-demand executions of the other payloads will be able to be triggered from ground sensors if necessary, as well as simple reception of other measurements that will complement the ones obtained on the satellite. The antennas for both the MWR and the LoRa experiments have been developed in-house, and will span the entirety of one of the 3U sides of the satellite. In this work, the latest development advances will be presented, together with an updated system overview and information about the operations that will be conducted. Results obtained from the test campaign are also presented in the conference
    corecore