396 research outputs found

    Guest editorial: Technology supported assessment in formal and informal learning

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    Consensus and dissent in the resolution of conflicts of competence by the Spanish Constitutional Court: the role of federalism and ideology

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    Given the lack of unambiguously constitutional foundations, Spain’s Constitutional Court (TC) has being playing a leading role in building the regulatory framework of the Autonomic State. This paper analyses whether this function is sufficient to explain the level of agreement among TC justices when adopting their resolutions, and in particular, on reaching unanimous rulings. If so, the legalist/federalist model would be a more adequate model to explain the behaviour of TC justices than the other models proposed in the literature on judicial behaviour: the attitudinal and the strategic models. A database has been constructed for this purpose with the 390 positive conflicts of competence between the central government and the autonomous communities resolved by the TC from 1981 to 2017, which have been used to estimate various explanatory models of unanimous rulings. The results obtained show the importance of the legalist/federalist model when attempting to explain unanimity in the Court’s pronouncements, but they also offer evidence that there are other factors that also influence the level of agreement among TC justices, remarkably the ideological ones

    Exploring the boundaries in the analysis of large particles by single particle inductively coupled plasma mass spectrometry: application to nanoclays

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    The analysis of microparticles by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) requires sample introduction systems that guarantee transport efficiencies similar to those obtained with dissolved standards across the size range covered. The utilization of a nebulisation system based on a linear pass spray chamber and a micronebuliser is discussed and optimized for the introduction of large inorganic particles. Limitations caused by incomplete ionisation or the counting limit of detectors affecting particle size characterisation are also considered. The procedure developed has been applied to the characterisation of suspensions of a natural clay (kaolinite), with a thickness in the range of a few nanometers and lateral dimensions up to 1 mu m. The application of different sensitivity conditions by the modification of the ion transmission allowed us to cover the whole size range of the suspension monitoring the Al-27 isotope and achieve a quantitative mass recovery with respect to ICP-MS analysis. Finally, the migration of nanoclays (montmorillonite) from food containers and their detection by SP-ICP-MS are presented. The results have been compared to those obtained by TEM, showing that nanoclays migrated from the containers into water

    An approach to the natural and engineered nanoparticles analysis in the environment by inductively coupled plasma mass spectrometry

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    Different approaches to the most relevant and recent studies and applications of inductively coupled plasma mass spectrometry (ICP-MS) applied to the analysis of natural and engineered nanoparticles in the environment are described. Usually several separation methods like polyacrylamide gel electrophoresis (PAGE), field-flow fractionation (FFF) and size exclusion chromatography (SEC) are used prior to the mass spectrometric measurements. In many cases the use of these hyphenated techniques provides important methodologies to know the bioavailability, mobility and toxicity of elements in life and environmental sciences. Alternatively, the capabilities of the single particle detection by ICP-MS (SD-ICP-MS) for the selective identification, characterization and determination of engineered nanoparticles will be also discussed

    A comparison of microsecond vs. millisecond dwell times on particle number concentration measurements by single particle ICPMS

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    With the growing popularity of nanomaterials in a wide variety of products and processes, the need to measure and characterize these materials has also grown. For metallic or metal-containing engineered nanoparticles (NPs), single particle ICP-MS (SP-ICP-MS) has been developed and is growing in popularity due to its ability to rapidly detect and characterize a large number of particles, determine particle size and size distributions, the particle number concentration in a sample, and the elemental mass concentration of both dissolved and particulate species. SP-ICP-MS has been applied to a wide variety of sample types1-5, demonstrating its versatility. A key variable in SP-ICP-MS, which must be applied correctly for accurate measurement of particle concentration, is the dwell time of the ICP-MS. Although this topic has been discussed previously6,7, this work will focus on direct comparisons of results using both microsecond and millisecond dwell times. Since a detailed version of this work is available8, only a brief description will be given here

    Silver nanoparticles-clays nanocomposites as feed additives: Characterization of silver species released during in vitro digestions. Effects on silver retention in pigs

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    Two different clay nanocomposites, as sepiolite-Ag and kaolinite-Ag, are studied as carriers for silver nano particles (AgNPs) oral administration as antimicrobial agent in additives for animal feed. A three-step digestibility assay, corresponding to stomach, small and large intestine simulations, has been followed. Ultrafiltration and asymmetrical flow field-flow fractionation (AF4) coupled to UV-Vis absorption and ICPMS detectors have been used for size characterisation of the silver species released during the in vitro digestibility assays. Less than 1% of the total silver is released in the stomach simulation step, probably due to the formation of silver chloride on the nanocomposite surface. In the case of the intestine simulation, silver released increases and tends to form complexes with the enzymes present in the media. A larger amount of silver was released from kaolinite-Ag compared to sepiolite-Ag (17 vs. 7%), probably due to a higher retention rate of silver shown by sepiolite, justified by its sorption capacity and fibrous structure. No evidences were found about a significant release of silver nanoparticles along the in vitro assay from any of the two nanocomposites studied. These results have been compared to the silver levels found in liver and faeces from weaned pigs fed with these supplements for 35 days and followed by basal diet free of silver for 4 weeks in an in vivo assay. Piglets fed with kaolinite-Ag retained more silver in liver than those receiving sepiolite-Ag, and the opposite was observed in faeces, although differences were not statistically significant. Silver levels found in muscles were below the limit of detection (0.009 mu g Ag g(-1)) in all cases

    Comportamiento de clofentecín frente al ácaro rojo Panonychus citri (Me Gregor) (Acari: Tetranychidae) y su predador Euseius stipulatus (Athias-Henriot) (Acari: Phytoseiidae) en los agrios españoles

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    [EN] Following clofentezine applications at three different crop stages in two citrus orchards (mandarines in 1991, and oranges in 1992), the evolution of both the citrus red mite Panonychus citri (MCGREGOR) and its predator the phytoseid mite Euseius stipulatus (Athias-Henriot) has been closely followed up for one year. Clofentezine showed a satisfactory citrus red mite control in summer applications coinciding wit insect scale tratments and in specific autumn applications. The product also proved to be safe for E. stipulatus which populations were hold at the same level in both trated and untreated plots, regardeless the time of application. Its safety for the predator, together with its good ecotoxicological profile will enable the usage of the product in IPM programs, in the frame of an increasingly exigent environmental plant context.[ES] Tras aplicaciones de clofentecín en un huerto de mandarinos (1991) y otro de naranjos (1992), en tres momentos diferentes del ciclo de cultivo, se ha seguido la evolución a lo largo de todo el año de las poblaciones del acaro rojo de los agrios Panonychus citri (MCGREGOR) su predador el acaro fitoseido Euseius stipulatus (AthiasHenriot). Clofentecín manifestó una eficacia satisfactoria frente a la plaga en aplicaciones de verano coincidentes con los momentos de tratamiento contra las cochinillas y en tratamientos específicos de otoño, así como, la baja nocividad del producto frente a E. stipulatus, cuyas poblaciones se han mantenido equivalentes en parcelas tratadas y testigo, independientemente del momento de aplicación. Su selectividad frente al predador, junto con sus buenas cualidades ecotoxicológicas, permiten la utilización del producto en programas de lucha integrada, en un contexto fitosanitario fuertemente exigente en relación al medio ambiente.Estos estudios han sido financiados por la empresa Schering España, S.A., mediante convenios de colaboración con la Universidad Politécnica de Valencia (Convenios n° 2/6000070/92 y 18/60000070/92)Santaballa, E.; Roca, M.; Laborda Cenjor, R. (1994). Comportamiento de clofentecín frente al ácaro rojo Panonychus citri (Me Gregor) (Acari: Tetranychidae) y su predador Euseius stipulatus (Athias-Henriot) (Acari: Phytoseiidae) en los agrios españoles. Boletin de Sanidad Vegetal: Plagas. 20(2):419-428. http://hdl.handle.net/10251/77057S41942820

    Influence of a commercial antithrombotic filter on the caval blood flow during neutra and valsalva maneuver

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    Anticoagulants are the treatment of choice for pulmonary embolism. When these fail or are contraindicated, vena cava filters are effective devices for preventing clots from the legs from migrating to the lung. Many uncertainties exist when a filter is inserted, especially during physiological activity such as normal breathing and the Valsalva maneuver. These activities are often connected with filter migration and vena cava damage due to the various related vein geometrical configurations. In this work, we analyzed the response of the vena cava during normal breathing and Valsalva maneuver, for a healthy vena cava and after insertion of a commercial Günther-Tulip® filter. Validated computational fluid dynamics (CFD) and patient specific data are used for analyzing blood flow inside the vena cava during these maneuvers. While during normal breathing, the vena cava flow can be considered almost stationary with a very low pressure gradient, during Valsalva the extravascular pressure compresses the vena cava resulting in a drastic reduction of the vein section, a global flow decrease through the cava but increasing the velocity magnitude. This change in the section is altered by the presence of the filter which forces the section of the vena cava before the renal veins to keep open. The effect of the presence of the filter is investigated during these maneuvers showing changes in wall shear stress and velocity patterns

    Size determination and quantification of engineered cerium oxide nanoparticles by flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry

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    Facing the lack of studies on characterization and quantification of cerium oxide nanoparticles (CeO2 NPs), whose consumption and release is greatly increasing, this work proposes a method for their sizing and quantification by Flow Field-flow Fractionation (FFFF) coupled to Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Two modalities of FFFF (Asymmetric Flow- and Hollow Fiber-Flow Field Flow Fractionation, AF4 and HF5, respectively) are compared, and their advantages and limitations discussed. Experimental conditions (carrier composition, pH, ionic strength, crossflow and carrier flow rates) are studied in detail in terms of NP separation, recovery, and repeatability. Size characterization of CeO2 NPs was addressed by different approaches. In the absence of feasible size standards of CeO2 NPs, suspensions of Ag, Au, and SiO2 NPs of known size were investigated. Ag and Au NPs failed to show a comparable behavior to that of the CeO2 NPs, whereas the use of SiO2 NPs provided size estimations in agreement to those predicted by the theory. The latter approach was thus used for characterizing the size of CeO2 NPs in a commercial suspension. Results were in adequate concordance with those achieved by transmission electron microscopy, X-ray diffraction and dynamic light scattering. The quantification of CeO2 NPs in the commercial suspension by AF4-ICP-MS required the use of a CeO2 NPs standards, since the use of ionic cerium resulted in low recoveries (99 ± 9% vs. 73 ± 7%, respectively). A limit of detection of 0.9 µg L-1 CeO2 corresponding to a number concentration of 1.8 × 1012 L-1 for NPs of 5 nm was achieved for an injection volume of 100 µL

    Wildlife and Antibiotic Resistance

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    Antibiotic resistance is a major human health problem. While health care facilities are main contributors to the emergence, evolution and spread of antibiotic resistance, other ecosystems are involved in such dissemination. Wastewater, farm animals and pets have been considered important contributors to the development of antibiotic resistance. Herein, we review the impact of wildlife in such problem. Current evidence supports that the presence of antibiotic resistance genes and/or antibiotic resistant bacteria in wild animals is a sign of anthropic pollution more than of selection of resistance. However, once antibiotic resistance is present in the wild, wildlife can contribute to its transmission across different ecosystems. Further, the finding that antibiotic resistance genes, currently causing problems at hospitals, might spread through horizontal gene transfer among the bacteria present in the microbiomes of ubiquitous animals as cockroaches, fleas or rats, supports the possibility that these organisms might be bioreactors for the horizontal transfer of antibiotic resistance genes among human pathogens. The contribution of wildlife in the spread of antibiotic resistance among different hosts and ecosystems occurs at two levels. Firstly, in the case of non-migrating animals, the transfer will take place locally; a One Health problem. Paradigmatic examples are the above mentioned animals that cohabit with humans and can be reservoirs and vehicles for antibiotic resistance dissemination. Secondly, migrating animals, such as gulls, fishes or turtles may participate in the dissemination of antibiotic resistance across different geographic areas, even between different continents, which constitutes a Global Health issue. Copyright © 2022 Laborda, Sanz-García, Ochoa-Sánchez, Gil-Gil, Hernando-Amado and Martínez
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