Environmental speciation of tin and lead by HPLC-ICP-MS

New methodologies have been developed for the determination of organotin and organolead compounds in environmental samples. Several high performance liquid chromatographic separations of organotin compounds have been tested and the best system (cation-exchange chromatography with methanol and a citrate buffer) employed for the determination of tributyltin (TBT), triphenyltin (TPhT), dibutyltin (DBT) and monobutyltin (MBT) in environmental samples. The coupling between high performance liquid chromatography (HPLQ and the inductively coupled plasma-mass spectrometer (ICP-MS) for this application has been modified to yield limits of detection of 0.44,0.26,1.4 and 0.23 ng. g-' as Sri for TBT, TPhT, DBT and MBT respectively. Different extraction procedures have been tested for the determination of organotin species in samples of environmental interest, such as sediments and biological materials. The values obtained for TBT, TPhT and DBT in the analysis of a mussel candidate reference material, CRM 477, have been incorporated in the certification campaign of this material. A liquid chromatographic separation for trimethyllead (TML) and triethyllead (TEL) has also been developed. Artificial rain water has been analysed for TML. The system proved to be valid for the determination of TML in this sample, even in the presence of high amounts of inorganic lead. Finally, isotope dilution analysis (IDA) was incorporated in the method. Tributyltin iodide (TBTI) and trimethyllead chloride (TMLCI), isotopically enriched in "Sn and "Pb, respectively, were synthesised. The mussel tissue CRM 477 was analysed with IDA-HPLC-ICPMS for TBT. As for the analysis without isotope dilution, the result obtained was incorporated in the certification campaign. The analysis with this methodology gave a better precision in the overall determination than external calibration analysis. Artificial rain water, at two different concentration levels, was analysed for TML with IDA-HPLC-ICP-MS. Better precision and accuracy was obtained for the analysis of this material with this method than when external calibration procedures were employed. IDA-HPLC-ICP-MS has proved to be a valid technique for the analysis of environmental samples. The technique simplifies the procedure, compensates for different sources of variability and, thus, the overall precision obtained in the analysis is improved compared to other calibration techniques.Standards, Measurements & Testing Programme from the European Unio

Paradigmas tecnológicos e estágios de diversificação tecnológica

This paper tests the existence of stages of technological diversification for a group of Asian and Latin-American countries since the late eighties; this is, when new technological paradigms emerged. Assuming that changes in technological specializations are linked to changes in productive specializations, this work look for evidences about the evolutions of technological structures in stages, this is, an initial phase of strong specialization in a few technical fields followed by a growing diversification, all along the period of expansion of techno-scientific paradigms. As the paradigms reduce their possibilities given the technological trajectories, technological opportunities become lower and U format-curve is expected. In general terms, countries reduced their technological distances with a wide reference area making more diversified their technological profiles. Nevertheless, different patterns of diversification/specialization were identified which must obey to other factors beyond the catching-up process. Among these factors, the role of technological leaders and transnational corporations is quite relevant.Este artigo contrasta a existência de estágios de diversificação tecnológica para um grupo de países da Ásia e da América Latina a partir dos anos 80, quando novos paradigmas tecnológicos surgiram. Assumindo que mudanças na especialização tecnológica estão associadas às mudanças na especialização produtiva, este trabalho busca evidências sobre uma evolução em estágios das estruturas tecnológicas, ou seja, uma fase inicial correspondente a uma elevada especialização em poucos campos técnicos, seguida de uma fase de crescente diversificação da base tecnológica que acompanha a fase de diversificação produtiva e de desenvolvimento tecnológico dos paradigmas. No entanto, a evolução dos paradigmas está condicionada a trajetórias que ao longo do tempo levam à redução de oportunidades e, em decorrência, a uma reversão (concentração) das estruturas com um formato esperado de U da tendência da evolução. O trabalho mostra que, em geral, os países reduziram suas distâncias tecnológicas em relação a uma área ampla de referência diversificando suas estruturas tecnológicas. No entanto, foram identificados distintos padrões de diversificação/especialização que devem estar associados a outros fatores além do nível de desenvolvimento dos países, especialmente ao papel desempenhado por Grandes Corporações Transnacionais

BQC: A free web service to quality control solar irradiance measurements across Europe

Classical quality control (QC) methods of solar irradiance apply easy-to-implement physical or statistical limits that are incapable of detecting low-magnitude measuring errors due to the large width of the intervals. We previously presented the bias-based quality control (BQC), a novel method that flags samples in which the bias of several independent gridded datasets is larger for consecutive days than the historical value. The BQC was previously validated at 313 European and 732 Spanish stations finding multiple low-magnitude errors (e.g., shadows, soiling) not detected by classical QC methods. However, the need for gridded datasets, and ground measurements to characterize the bias, was hindering the BQC implementation. To solve this issue, we present a free web service, www.bqcmethod.com, that implements the BQC algorithm incorporating both the gridded datasets and the reference stations required to use the BQC across Europe from 1983 to 2018. Users only have to upload a CSV file with the global horizontal irradiance measurements to be analyzed. Compared to previous BQC versions, gridded products have been upgraded to SARAH-2, CLARA-A2, ERA5, and the spatial coverage has been extended to all of Europe. The web service provides a flexible environment that allows users to tune the BQC parameters and upload ancillary rain data that help in finding the causes of the errors. Besides, the outputs cover not only the visual and numerical QC flags but also daily and hourly estimations from the gridded datasets, facilitating the access to raster data.We thank the Instituto de Estudios Riojanos for funding part of the web service within the program Estudios Científicos de Temática Riojana, Spain. This research used resources from the Supercomputing Castilla y Leon Center (SCAYLE, www.scayle.es), funded by the European Regional Development Fund (ERDF). We would also like to thank the EU meteorological networks that freely distribute their datasets and particularly those researchers who helped us in retrieving these data: Aku Riiëla and Anders Lindfors (FMI), Virginie Gorjoux (Météo France), Sandra Andersson (SHMI), and Jakub Walawender (IMGW-PIB). Finally, we thank the CMSAF and ECMWF for freely distributing their products, and particularly Jörg Trentmann, for providing a beta version of CLARA-A2.1. RU is a postdoc from the University of La Rioja working as a visiting scientist at the European Commission’s Joint Research Center (JRC). RU is funded by the Plan Propio de la Universidad de La Rioja, Spain and V Plan Riojano de I+D, Spain . The views expressed here are purely those of the authors and may not, under any circumstances, be regarded as an official position of the European Commission

Emerging therapeutic strategies to enhance HDL function

Epidemiologic studies indicate a strong inverse correlation between plasma levels of high-density lipoproteins (HDL) and cardiovascular disease (CVD). The most relevant cardioprotective mechanism mediated by HDL is thought to be reverse cholesterol transport (RCT). New insights in HDL biology and RCT have allowed the development of promising agents aimed to increase HDL function and promote atherosclerosis regression. In this regard, apo-AI analogs and CETP inhibitors dalcetrapib and anacetrapib have aroused a great interest and opened new expectations in the treatment of CVD

Actitudes ante la muerte (preocupación,ansiedad,temor) y religiosidad

Fac. de PsicologíaTRUEProQuestpu