A sustainable and simple energy dispersive X-ray fluorescence method for sulfur determination at trace levels in biodiesel samples via formation of biodiesel spots on a suitable solid support

The aim of the present work is the development of a simple, sensitive and sustainable EDXRF method for the determination of trace amounts of sulfur in biodiesel samples. In this method, the deposition of several microliters of sample onto an organic thin layer and the analysis of the resulting adsorbed biodiesel spot by benchtop EDXRF is proposed. A careful study was performed to select the volume and the best solid support to deposit biodiesel samples, including filters made of different materials (glass fiber, Nylon, cellulose, paper) and a commercial disposable absorbent pad (UltraCarry, Rigaku). A critical issue that limits the use of most of these solid supports was the relative high blank signals that hamper the determination of sulfur at trace levels. Finally, it was found that best strategy was the deposition of 50 µL of biodiesel on the UltraCarry sample retainer. Operating conditions for EDXRF measurements were also evaluated to obtain the best instrumental sensitivity for sulfur determination (Excitation: 20 kV, no primary filter, measurement time: 300 s). Using the best analytical conditions the quantification limit of the method was 7 mg kg -1 of sulfur. This value is even better than the one reported in the ASTM D4294 method (LOQ: 16.0 mg kg -1 ) but using a sample amount 100 times smaller. The linearity was confirmed in the range of 10–100 mg kg -1 by analyzing a set of commercial biodiesel standards. Accuracy and precision of the results, evaluated by the analysis of samples prepared with the same matrix as the standards, with levels of 20, 40 and 75 mg kg -1 of sulfur, and processed as unknowns, proved acceptable (Recoveries: 94.3–110.6%, RSD: 10.8–13.6%, n = 3) for the intended purpose. Overall, the performance of the method developed is promising and it could be used to determine trace amounts of sulfur in biodiesel samples in a simple, sustainable and cost-effective way. Furthermore, since the original sample is adsorbed onto a solid support, repeat confirmatory analyses on the same specimen, if needed, can be carried out

Tesis doctorals i treballs de recerca universitaris sobre comunicació als Països Catalans, 1954-1996 : aproximació bibliomètrica

Aquí es presenta, per primera vegada, una anàlisi bibliomètrica sobre els treballs acadèmics especialitzats en comunicació realitzats a les universitats i escoles de grau superior dels Països Catalans, o bé presentats per autors d'aquest territori a d'altres centres acadèmics de la resta de l'Estat o de l'estranger. S'analitzen quantitativament totes les tesis doctorals, tesis de mestratge, treballs de doctorat, tesis de llicenciatura i tesines fi de carrera defensades públicament davant tribunals acadèmics des de 1954, data de la primera recerca localitzada. També s'hi inclou un llistat exhaustiu amb les dades bàsiques de 285 tesis doctorals.This first bibliometric analysis of academic publications on communication includes both those research papers presented at Catalan universities and schools of higher education and those presented by Catalan authors at universities and schools outside of Catalonia. The authors provide a quantitative analysis of all doctoral dissertations, master's theses, doctoral research projects, and final term papers which were publicly defended before academic boards between 1954 (the date of the earliest project located by the authors) and 1996. The authors also include a complete list with basic information on 285 doctoral dissertations

Atmospheric instability analysis and its relationship to precipitation patterns over the western Iberian Peninsula

International audienceThermodynamic and dynamic atmospheric stability indices will be analysed in order to classify the rainfall types occurred in western Iberia and provide information about the associated meteorological phenomena and preferred regional instability sources. In this work, instability sources over the western Iberian Peninsula will be characterised by means of radiosonde station data and reanalysis data sets from the European Centre for Medium-Range Weather Forecasts (ECMWF), for the period 1971?2002. Dynamic stability indices such as the Q vector divergence (dQ) or the potential vorticity anomaly in the 330 K isentropic surface (PV) have been calculated with the aim of establishing different atmospheric stability scenarios. Furthermore, thermodynamic atmospheric stability contribution has been also evaluated with Total Totals index (TT) and moisture availability was inferred from circulation weather types (CWTs). The first results of this work assess the combined dynamic-thermodynamic preferred conditions, synoptic situations and humidity sources, leading to precipitation events over the western Iberian Peninsula and prove the essential role of CWT patterns on the rainfall genesis

Inter-municipal cooperation and costs: Expectations and evidence

Austerity and fiscal crisis make the search for cost saving reforms in local government more critical. While cost savings from privatization have frequently proven ephemeral, inter-municipal cooperation has been a relatively understudied reform. We analyze the literature on cost savings under cooperation and find savings are dependent on (1) the cost structure of public services, particularly those related to scale and density economies and externalities, (2) the structure of local government (size, metropolitan location, powers granted by the nation or regional state), and 3) the governance framework at the local/regional scale where cooperation varies from informal to formal. European studies give more emphasis to cost savings, while US studies focus on coordination concerns arising from the higher degree of devolution in the US local government system

Instability and its relation to precipitation over the Eastern Iberian Peninsula

International audienceSynoptic situations producing rainfall at four rawinsonde observatories at eastern Spain are classified as stratiform or convective depending on dynamic and thermodynamic instability indices. Two daily radiosonde and daily-accumulated precipitation data from four observatories in Eastern Spain are used: Madrid-Barajas (MB), Murcia (MU), Palma de Mallorca (PA) and Zaragoza (ZA). We calculated two thermodynamic instability indices from radiosonde data: CAPE and LI. Likewise, from ERA40 reanalysis data we have calculated the Q vector divergence over the Iberian Peninsula and Balearic Islands, as a parameter describing dynamical instability. Synoptic situations producing rainfall were classified as convective or stratiform, satisfying a criterion based on the values of dynamic and thermodynamic indices at each observatory. It is observed that the number of days with stratiform precipitation related to the total number of precipitation days follows a consistent annual pattern

The flood event that affected Badajoz in November 1997

International audienceThe flooding episode of November 1997 in Badajoz was one of the most dramatic catastrophes in Spain: as a result, there were 21 fatalities and huge financial damages. The main purpose of this work is to assess the prevailing synoptic conditions as well as detailing the mesoscale effects by means of moisture sources and dynamic and thermodynamic instability analysis involved in the November 1997 Spanish severe weather episode. In order to achieve the above, this flood event is described in terms of moisture content evolution by means of individual particle simulation along 3-day back-trajectories. A Lagrangian model is applied in order to characterize the atmospheric particles involved in the focused case (localization, height and specific humidity) which give rise to sudden precipitation stream. Geopotential height and temperature fields were used to describe the synoptic situation. Thermodynamic indices, such as CAPE, SWEAT and KI, and dynamic parameters like potential vorticity anomaly at 330 K isentropic surface and Q vector divergence were also calculated in order to complete the analysis and to give a thorough weather frame taking into account the atmospheric instability. The results of this work suggest this flood event was due mainly to strong dynamic instability along with large amounts of moisture advected by a trough, while the thermodynamic instability played a secondary role. Finally, a new methodology based on a technique proposed by Tremblay (2005) has been developed in order to separate the precipitation into stratiform and convective components. It is evident that the event was associated with a predominant convective regime

Factors Explaining Inter-municipal Cooperation in Service Delivery: A Meta-Regression Analysis [WP]

Inter-municipal cooperation is an important public service delivery reform, whose drivers move beyond simple concerns with costs and economic efficiency, to policy issues related to governance structure and spatial context. We conduct a meta-regression analysis based on the existing multivariate empirical literature to explore what factors explain divergence in results in the existing empirical studies. We find strong evidence that fiscal constraints, spatial, and organizational factors are significant drivers of cooperation. Our meta regressions do not yield results to explain divergence in results on community wealth, economies of scale or racial homogeneity. More studies on these factors are needed to understand how these factors might affect cooperation. Future theoretical and empirical research should give more attention to spatial and organizational factors to develop a better understanding of factors driving cooperation and how they differ across local government structures and regions

High-speed rail accessibility: a comparative analysis of urban access in Los Angeles, San Francisco, Madrid, and Barcelona

This paper is intended to set the context for policy discussion on HSR feasibility from the perspective of station accessibility. We compare the proposed Los Angeles - San Francisco HSR corridor to the functioning HSR line between Madrid and Barcelona to assess relative station accessibility based on urban structure. Our methodology assesses socioeconomic and spatial characteristics of mono-centric versus polycentric cities that may affect HSR accessibility. By addressing challenges of unit (urban geography), data series (normalization) and identifying four key components of HSR attractiveness (population, population density, income and employment) we have created a methodology that allows us to assess relative station accessibility in the four compared metropolitan areas. We find urban structure limits the potential accessibility of HSR in the California context, and warn HSR planners they should proceed with caution