Magnetic dispersive solid phase microextraction coupled with on-line chemical vapor generation method to extraction/preconcentration of mercury from environmental samples and determination by graphite furnace atomic absorption spectrometry.

Mercury (Hg) is classified as priority hazardous substances. Concentrations found in the aquatic environment are at trace levels as result of natural processes, such as erosion and volcanism, and anthropogenic discharges related mainly to industrial and mining activities. Mercury is one of the most potent neurotoxins known, showing a high number of adverse health effects in animals and humans. For this reason, a simple and rapid method for the determination and preconcentration of mercury in environmental waters is proposed. This work is based on magnetic dispersive solid phase microextraction (MDSPME) coupled with on-line chemical vapour generation (CVG). Graphite furnace atomic absorption spectrometry (GFAAS) was employed for the quantification of Hg. In the preconcentration step, a shell structured Fe3O4@graphene oxide was suspended in the ionic liquid carrier (1-n-butyl-3-metilimidazolium tetrafluoroborate [BMIM][BF4]), obtaining a stable colloidal suspension called ferrofluid. This sorbent possesses as large contact surface area and a high density of polar groups on its surface. The nanoparticles, when finely dispersed in the sample solution, result in almost complete extraction of Hg within a few seconds. All experimental and instrumental variables were optimized and the method was adequately validated by the analysis of certified reference materials of environmental waters. Acknowledgements The authors would like to thank Plan Propio “Proyecto Puente” de la Universidad de Málaga for financial support of this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Integración flexible de workflows científicos en entornos de computación dinámicos

La aparición de potentes infraestructuras de computación Grid ha impulsado un creciente interés por parte de la comunidad científica para automatizar la ejecución de sus experimentos. Para ello, la utilización de workflows científicos resulta clave de cara a aprovechar las oportunidades que presentan este tipo de infraestructuras, debido principalmente a las características que presentan: están formados por un elevado número de tareas con un alto coste computacional, que manejan grandes volúmenes de datos complejos y que requieren una gestión adecuada de los recursos tanto software como hardware disponibles. Sin embargo, la complejidad de los propios workflows y de las infraestructuras de computación provoca que el proceso de scheduling resulte complejo y difícil. Las propuestas actuales utilizan un broker de recursos que facilita esta tarea pero provoca que el diseño del workflow esté fuertemente acoplado con el middleware que gestiona la infraestructura. Esto imposibilita la utilización conjunta de diferentes Grids, la compartición y portabilidad de los workflows y la gestión flexible del ciclo de vida de los mismos. Para solucionar estas limitaciones, se plantea una infraestructura flexible a la hora de integrar workflows de diferentes lenguajes, diversas infraestructuras de computación (Grid, Cloud, etc.) y componentes de gestión que permitan enriquecer y mejorar la ejecución de los workflows. La utilización de redes de Petri de alto nivel se plantea como base, dada la amplia experiencia en este campo por parte del Grupo de Integración de Sistemas Distribuidos y Heterogéneos (GIDHE), grupo en el que se enmarca la línea de investigación del autor. Esta propuesta introduce nuevos retos en la decisión de las infraestructuras en las que ejecutar los workflows (meta-scheduling), siendo la simulación una alternativa muy adecuada al ser capaz de prever el comportamiento del workflow en diferentes escenarios

Solid sampling determination of ZnO nanoparticles in eyeshadows by graphite furnace atomic absorption spectrometry

The application of nanoparticles (NPs) in science and technology is a fast growing field. Therefore, reliable and straightforward analytical methods are required for their fast determination in different types of samples. In this work, a method that enables the determination of the average size of ZnO NPs, besides their concentration, discriminating them from ionic zinc, has been optimized. The method is based on solid sampling high-resolution continuum source electrothermal atomic absorption spectrometry (SS-HR-CS-GFAAS), and has been applied to determination and characterization of ZnO NPs in cosmetic samples. Recently, graphite furnace atomic absorption spectrometry has been introduced as a new tool to determine the size of nanoparticles by evaluation of the following parameters: atomization delay (tad) and atomization rate (kat). In this work both parameters (besides peak area) have been obtained from absorbance signals for a line of Zn with low sensitivity. Two multiple response surface designs have been used in order to optimize the adequate furnace program to achieve our aims. All the optimization experiments were performed using baby´s skin irritation protective cream. The optimized furnace program is shown in Table 1. Table 1. Optimized furnace program The size calibrations were performed against solid (powered) ZnO standards, from 50-nm to 500-nm sized nanoparticles. The correlation coefficients (R value) of the linear calibration were not worse than 0.9982. The optimized method was tested in other types of cosmetic samples such as eyeshadow samples with good results. The determination of the MNPs’ size was validated by transmission electron microscopy (TEM) and the Zn concentration in the solid samples was validated by atomic fluorescence spectroscopy (AFS). Acknowledgements (optional) [Garamond font, 10 points] The authors would like to thank Plan propio “Proyecto Puente” de la Universidad de Málaga for financial support of this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Rapid magnetic microextraction to preconcentrate and determinate cadmium from environmental samples

A novel and greener ultrasonically assisted/modified cloud point extraction procedure for the preconcentration and extraction of trace cadmium from environmental samples was developed. The sorbent material was fabricated by scattering of magnetic iron nanoparticles (MNPs) over graphene oxide (GO) to obtain magnetic graphene oxide (MGO). The material was suspended in the ionic liquid 1-n-butyl-3-metilimidazolium tetrafluoroborate [BMIM][BF4]. The obtained stable colloidal suspension is named ferrofluid. GO presents excellent adsorbent properties for organic species due to the presence of the electronic π system. For this reason, the organic ligand [1,5-bis-(2-dipyridyl) methylene] thiocarbonohydrazide (DPTH) was used in order to form an organic complex of Cd. Once the DPTH ligand has been added to sample, the ferrofluid was injected and finely dispersed in the sample solution in order to extract the formed chelate as shown in Fig. 1. The complete adsorption of the quelate took place within few seconds, after that the solid was separated from the solution with the aid of a strong magnet. Cadmium ions were desorbed from the material with 1 mL of 5% acid nitric solution and quantified by electrothermal atomic absorption spectrometry (ETAAS). The main parameters affecting the extraction and the furnace program were optimized using one-at-time method. The analytical performance under optimum conditions are the following: LOD: 0.005 µg/L, LOQ: 0.017 µg/L. Linear calibration: 0-0.25 µg/L and EF: 200. The reliability of the developed procedure was tested by relative standard deviation (% RSD), which was found to be < 5% (1.3%). The performance of the proposed procedure was checked by applying to certified reference material and spiking standard in real samplesUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

SOLUCIÓN ANALÍTICA DE MECANISMOS USANDO GRUPOS DE ASSUR.

Se presentan soluciones analíticas para el grupo primario R y el grupo de Assur de clase II RRR, usando notación polar compacta y defiendo la inversión geometrica para llegar a una solución lineal, las soluciones analíticas son codificadas como funciones de MatLab y validadas mediante el análisis de un mecanismo por técnicas gráficas

SOLUCIÓN ANALÍTICA DE MECANISMOS USANDO GRUPOS DE ASSUR.

Se presentan soluciones analíticas para el grupo primario R y el grupo de Assur de clase II RRR, usando notación polar compacta y defiendo la inversión geometrica para llegar a una solución lineal, las soluciones analíticas son codificadas como funciones de MatLab y validadas mediante el análisis de un mecanismo por técnicas gráficas

Minimum Information Required to Annotate Food Safety Risk Assessment Models (MIRARAM)

Abstract In the last decades, mathematical models and model-based simulations became important elements not only in the area of risk assessment concerning microbiological and chemical hazards but also in modelling biological phenomena in general. Unfortunately, many of the developed models are published in non-standardized ways, which hinders efficient exchange, re-use and continuous improvement of models within the risk assessment domain. The establishment of guidelines for model annotation is an important pre-condition to overcome these obstacles. Additionally, implementation of annotation guidelines can improve transparency, quality control and even aid the clarification of intellectual property rights. Here, we address the question of "What is the minimum set of metadata that should be provided for a model in the risk assessment domain?". The proposed guideline focuses on food safety risk assessment models and is called "Minimum Information Required to Annotate food safety Risk Assessment Models (MIRARAM)". MIRARAM supports the model creator during the model documentation step and could also be used as a checklist by scientific journal editors or database curators. Software developers could take up MIRARAM and develop easy-to-use software tools or new features in existing programs that can help model creators to provide proposed model annotations in harmonized file formats. Based on experiences from similar guidelines in related scientific disciplines (like systems biology), it is expected that MIRARAM could contribute to the promotion of application and re-use of models as well as to implementing more standardized quality control in the food safety modelling domain

PRINCIPIOS DE FUNCIONAMNIENTO Y CONSTRUCCIÓN DE UNA CELDA DE COMBUSTIBLE DE ÀCIDO FOSFÒRICO (PAFC)

El siguiente articulo muestra los principios básicos de funcionamiento de las celdas de combustible, en especial la de la celda PAFC. También se nombran algunas de las características que se deben de tener en cuenta al momento de su construcción y algunas de las empresas que se encargan de distribuir este tipo de celdas y sus componentes a nivel mundial

PRINCIPIOS DE FUNCIONAMNIENTO Y CONSTRUCCIÓN DE UNA CELDA DE COMBUSTIBLE DE ÀCIDO FOSFÒRICO (PAFC)

El siguiente articulo muestra los principios básicos de funcionamiento de las celdas de combustible, en especial la de la celda PAFC. También se nombran algunas de las características que se deben de tener en cuenta al momento de su construcción y algunas de las empresas que se encargan de distribuir este tipo de celdas y sus componentes a nivel mundial