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  • 1
    Publication Date: 1986-01-20
    Print ISSN: 0014-5793
    Electronic ISSN: 1873-3468
    Topics: Biology , Chemistry and Pharmacology
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  • 2
    Publication Date: 2014-04-03
    Description: LIRIC (LIdar-Radiometer Inversion Code) is applied to combined lidar and sun photometer data from Granada EARLINET and AERONET station corresponding to different case studies. The main aim of this analysis is to evaluate the stability of LIRIC output volume concentration profiles for different aerosol types, aerosol loadings and vertical distribution of the atmospheric aerosols. For this purpose, in a first part, three case studies corresponding to different atmospheric situations are analysed to study the influence of the user-defined input parameters in LIRIC when varied in a reasonable range. Results of this study evidence the capabilities of LIRIC to retrieve vertical profiles of microphysical properties during daytime by combination of the lidar and the sun photometer systems in an automatic and self-consistent way. However, spurious values may be obtained in the lidar incomplete overlap region depending on the structure of the aerosol layers. In a second part, the use of a second sun photometer located in Cerro Poyos, in the same atmospheric column as Granada but at higher altitude, allowed us to obtain LIRIC retrievals from two different altitudes with independent sun photometer measurements in order to check the self-consistency and robustness of the method. Retrievals at both levels are compared, providing very good agreement (differences below 5 µm 3 /cm 3 ) in those cases with the same aerosol type in the whole atmospheric column. However, some assumptions such as the height-independency of parameters (sphericity, size distribution or refractive index, among others) need to be carefully reviewed for those cases with presence of aerosol layers corresponding to different types of atmospheric aerosols.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
    Publication Date: 2018-02-20
    Description: Determining the association constants of radicals to biomimetic systems is not a simple task because of the inherent experimental difficulties associated to their “in-situ” generation together with their high chemical instability, requiring the use of radical trapping agents in combination with, for example, magnetic (eg, EPR) and/or time-resolved techniques (eg, frequency comb spectroscopy) to indentify and quantify them. Here, we have exploited the unique electrochemical properties of arenediazonium ions, ArN 2 + , to estimate the association constant of the electrochemically generated aryl radicals derived from benzenediazonium ions, BD, with sodium dodecyl sulfate (SDS) micelles. When ArN 2 + are reduced on an Hg electrode, they acquire an electron yielding the corresponding arenediazenyl radical, ArN 2 • , which undergoes further decomposition to produce the aryl radical, Ar • . BD partitions between the aqueous and micellar pseudophases, and, upon increasing [SDS], peak currents decrease and the peak potentials are shifted. Results indicate that the association constant of the aryl radical to SDS micelles is 3 times higher than that of the parent substrate as a consequence of its higher hydrophobicity compared with that of the parent molecule. The method is feasible because of the large number of arenediazonium ions that can be prepared and because it does not depend on the reactivity of the electrochemically generated radical. Combining arenediazonium ions (as probe molecules) with voltammetric measurements provides a rapid, low-cost method to estimate the partitioning of aryl radicals to biomimetic systems.
    Print ISSN: 0894-3230
    Electronic ISSN: 1099-1395
    Topics: Chemistry and Pharmacology , Physics
    Published by Wiley
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  • 4
    Publication Date: 2015-03-28
    Description: We studied the fate of Cu in contaminated semiarid soils from two areas with different mining activities in central Chile. Several regression models were evaluated to use soil physicochemical characteristics to predict solubility, partitioning, and activity of Cu. Furthermore, we hypothesize that the type of Cu mining compound (smelter dust versus tailing sand) can be another important variable determining the bioavailability of Cu. In the studied neutral to alkaline soils, soil organic matter (SOM) enhanced Cu solubility most probably through the formation of organic complexes with dissolved organic C (DOC). As a consequence, Cu solubility and partitioning were better explained by DOC concentration than by SOM content. On the other hand, Cu activity was mainly related to soil pH and was not affected by DOC. Although we found differences between the two study areas, Cu solubility and partitioning might not be as dependent upon the origin of the Cu mining compound as upon other physiochemical characteristics that influence the concentration and characteristics of DOC. Total Cu, pH, and DOC would be the most important variables to consider on Cu solubility, however, data about the nature of SOM may certainly improve the prediction models. Thus, multiple binding site models between Cu and DOC should be studied to improve predictions of Cu solubility.
    Print ISSN: 1436-8730
    Electronic ISSN: 1522-2624
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 5
    Publication Date: 2019
    Description: Abstract One of the main problems of hydrologic/hydrodynamic routing models is defining the right set of parameters, especially on inaccessible and/or large basins. Remote Sensing techniques provide measurements of the basin topography, drainage system and channel width, however current methods for estimating riverbed elevation are not as accurate. This paper presents methods of altimetry data assimilation for estimating effective bathymetry of a hydrodynamic model. We tested past altimetry observations from satellites ENVISAT, ICESAT and JASON 2 and synthetic altimetry data from satellites ICESAT 2, JASON 3, SARAL and SWOT to assess future/present mission's potential. The data assimilation (DA) methods used were Direct Insertion, Linear Interpolation, the SCE‐UA optimization algorithm and an adapted Kalman Filter developed with hydraulically based variance and covariance introduced in this paper. The past satellite altimetry data assimilation was evaluated comparing simulated and observed water surface elevation (WSE) while the synthetic altimetry DA were assessed through a direct comparison with a “true” bathymetry. The SCE‐UA and hydraulically based Kalman Filter methods presented the best performances, reducing WSE error in 65% in past altimetry data experiment and reducing biased bathymetry error in 75% in the synthetic experiment, however the latter method is much less computationally expensive. Regarding satellites, it was observed that the performance is related to the satellite inter‐track distance, as higher number of observation sites allows more accurate bed elevation estimation.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2019
    Description: Abstract Aim Most of the fundamental questions in conservation biogeography require the description of species geographic boundaries and the identification of discrete biological units within these boundaries. International conservation efforts and institutions rely mainly on traditional taxonomic approaches for defining these boundaries, resulting in significant cryptic diversity going undetected and often extinct. Here, we combine high‐throughput genomic data with publicly available environmental data to identify cryptic diversity in the threatened bird's‐eye primrose (Primula farinosa). We aim to characterize evolutionary lineages and test whether they co‐occur with changes in environmental conditions. These lineages can be used as intraspecific units for conservation to enhance assessments regarding the status of threatened species. Location Europe and temperate Asia (latitude, 40–65°N; longitude, 10°E–115°W). Methods We genotyped 93 individuals from 71 populations at 1,220 loci (4,089 SNPs) across the Eurasian distribution of P. farinosa. We used phylogenomic and population structure approaches to identify intraspecific lineages. We further extracted statistically derived and remotely sensed environmental information, that is land cover, climate and soil characteristics, to define the biotic and abiotic environment inhabited by each lineage and test for niche similarities among lineages. Additionally, we tested for isolation by distance among populations and applied linear and polynomial regressions to identify lineage‐environment associations. Results Analyses of genomic data revealed six major lineages within P. farinosa corresponding to distinct geographic areas. Niche similarity tests indicated that lineages occupy distinct abiotic and biotic space. Isolation by distance indicated that geography alone cannot explain genetic divergence within P. farinosa, while lineage‐environment associations suggested potential adaptation to different abiotic conditions across lineages. However, relationships with the land cover classes, a proxy for habitat, were weaker. Main conclusion Our results highlight the need for incorporating intraspecific diversity in global assessments of species conservation status and the utility of genomic and publicly available environmental data in conservation biogeography.
    Print ISSN: 1366-9516
    Electronic ISSN: 1472-4642
    Topics: Biology
    Published by Wiley
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  • 7
    Publication Date: 2019
    Description: Abstract In Eastern Boundary Upwelling Systems (EBUS), the upwelling‐favorable wind speeds decrease toward the coast in the so‐called wind drop‐off coastal strip, which has been shown to be influential on the coastal upwelling dynamics, particularly in terms of the relative contributions of Ekman drift and Ekman suction to coastal upwelling. Currently, the wind drop‐off length scale is not properly resolved by the atmospheric forcing of regional ocean models in EBUS, featuring a smoother cross shore wind profile that results in stronger near shore speeds that could partly explain the coastal cold bias often found in those model simulations. Here, as a case study for the upwelling system off Central Chile, the sensitivity of upwelling dynamics to the coastal wind reduction is investigated using a regional oceanic model (ROMS). Coastal wind profiles at different resolutions are first generated using a regional atmospheric model, validated from altimeter data, and then used to correct the coarse atmospheric wind forcing used for sensitivity experiments with ROMS. It is shown that the wind drop‐off correction induces a reduction in the oceanic coastal jet intensity, a stronger poleward undercurrent and a coherent offshore Ekman drift. It also yields a significant reduction of the cold bias along the coast compared to the simulation with “uncorrected” winds. Such reduction cannot be solely explained by the reduced Ekman transport only partially compensated by increase in Ekman suction. The analysis of the surface heat budget reveals in fact that an important contributor to the cooling reduction along the coast in the presence of coastal wind drop‐off is the heat flux term mediated by the reduction in the mixed‐layer depth. Overall, our results illustrate the non‐linear response of the upwelling dynamics to the coastal wind profiles in this region.
    Print ISSN: 2169-9275
    Electronic ISSN: 2169-9291
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
    Publication Date: 2019
    Description: Abstract Modeling the ionosphere during disturbed periods is one of the most challenging tasks due to the complexity of the phenomena that affect the electric fields and the whole thermosphere environment. It is well known that both, prompt penetration electric fields and large amounts of energy deposited in the polar region during disturbed periods, produce significant disturbances in the global electron density distribution, in particular, in the equatorial ionization anomaly (EIA) development. Besides, the disturbance dynamo, traveling atmospheric disturbances and traveling ionospheric disturbances also affect the EIA density distribution. In this work we use the Sheffield University Plasmasphere‐Ionosphere Model at INPE (SUPIM‐INPE), to simulate the drastic effects that were observed at the low latitude ionosphere in the Brazilian region during a very intense magnetic storm event, the so‐called 2003 Halloween storms. In the absence of measured vertical drift during the storm, a new vertical drift deduced from the interplanetary electric field combined with the time variation of the F‐region virtual height is used as input. The simulation results showed that, in the case of the disturbed thermospheric wind, the ionospheric observations are better explained when a novel traveling wave‐like disturbance propagating from north to south, at a velocity equal to 300 m/s, is considered.
    Print ISSN: 2169-9380
    Electronic ISSN: 2169-9402
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
    Publication Date: 2019
    Description: Abstract The crystallisation of fluoride nanocrystals (NCs) in chemically and mechanically stable aluminosilicate glasses has showed interesting optical properties even for small crystal fractions (10‐15 wt%). When Rare‐Earth (RE) ions are used as dopants, crystal‐like features can be reproduced and an increase in the emission and/or energy transfer (ET) processes, with respect to the starting glasses, is observed. A crucial point for these materials is the study of the local surrounding of RE ions and their incorporation in the NCs. In fact, the effective concentration in the NCs can be much higher than the nominal concentration, up to one order of magnitude or even higher. The knowledge of RE ions incorporation in the NCs permits choosing proper doping levels to optimize both linear and nonlinear optical properties. In this work, transparent oxyfluoride glass‐ceramics with LaF3 NCs, doped with Nd3+ and Er3+ using oxide and fluoride precursors, were prepared by melt‐quenching method and controlled crystallisation. The local surrounding of the RE ions was studied using X‐Ray Absorption spectroscopy (XAS), Electron Paramagnetic Resonance (EPR) and Photoluminiscence (PL). The results show that most of RE ions are already in a fluorine‐rich amorphous environment even in the initial glass. The crystallisation process provokes the RE ions redistribution and incorporation in the fluoride NCs. The different RE precursors, used as oxides or fluorides, have an influence on the incorporation of the RE in the NCs and, as a consequence, on the final optical properties.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley
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  • 10
    Publication Date: 2014-08-29
    Description: The type of specific intermolecular and interionic interactions that are established when an ionic liquid is dissolved in water was here analysed. The study of the solvatochromic response of dipolarity micro-sensors based on Reichardt E T (30) and Kamlet–Abboud–Taft solvent scales and the application of the solvent exchange model confirmed the formation of different intersolvent complexes in binary mixtures of (water + [C 4 mim] [BF 4 ]/[Br]) type. These complexes provide H-bond or electron pairs to the polar network, respectively. Moreover, for 4-methoxybenzenesulfonyl chloride hydrolysis reaction in the (water + [C 4 mim] [BF 4 ]) system, a higher inhibition (13 times) on the k obs values was observed. Multiple linear regression analysis that allows confirming the solvent effect upon the reactive system is due to the hydrogen-bond donor properties of intersolvent complex formed. Then, the correlation between two different solvent-dependent processes proved to be successful. Copyright © 2014 John Wiley & Sons, Ltd. From the analysis of dipolarity micro-sensors solvatochromic response and the application of solvent exchange model, we determine the tendency of the different components of binary mixtures formed by (W + ILs) to interact with potential solutes. Therefore, the analysis of correlation between the microscopic properties and k obs values for a hydrolysis reaction allows us to understand the chemical behaviour observed.
    Print ISSN: 0894-3230
    Electronic ISSN: 1099-1395
    Topics: Chemistry and Pharmacology , Physics
    Published by Wiley
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