403 research outputs found

    La inaplicación de condiciones laborales establecidas en un convenio colectivo estatutario

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    El objetivo del trabajo es el análisis de la inaplicación de las condiciones laborales establecidas en un convenio colectivo estatutario, que constituye una importante excepción a la eficacia personal general de los convenios colectivos. Para dicho análisis se parte de la evolución normativa que ha afectado a esta institución, así como las causas que han de invocarse, las materias sobre las que puede proyectarse la inaplicación y el procedimiento que se ha de seguir para proceder al descuelgue en el ámbito empresarial.Grado en Derech

    Development and Validation of Analytical Methods for Mycotoxins in Food, Medicinal Herbs and Feed

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    This thesis concerns with the development and the validation of analytical methods for the determination of the mycotoxins aflatoxin B1, zearalenone and patulin, which occur frequently in food and feed. The toxic syndromes produced by them when ingested are known as mycotoxicoses. One of the first reports in history of mycotoxicoses is ergotism, caused by the fungus Claviceps purpurea. Nowadays ergotism is of minor importance; however the problem of mycotoxicoses and long term sub-acute exposure has not faded. Therefore, regulations have been established in many countries, and reliable testing methodology is needed to implement and enforce the regulatory limits. So far, several hundred different mycotoxins have been discovered, exhibiting different structural diversity, with various chemical and physicochemical properties, but only a few present significant food safety challenges. Among these are aflatoxins and ochratoxin A (produced by Aspergillus sp.), fumonisins, trichothecenes such as T-2, HT-2 toxins, deoxynivalenol and zearalenone (produced by Fusarium sp.), patulin (produced by Penicillium sp.) and ergot alkaloids (produced by Claviceps sp.) the most frequent occurring mycotoxins with the highest potential to adverse effects in humans and animals. The work of this thesis can be clustered into three parts as follows: (I) Method comparison and collaborative trial for the determination of aflatoxin B1 in medicinal herbs. This study was initiated upon the request of the European Pharmacopoeia since the regulatory limits for aflatoxin B1 in medicinal herbs were discussed in that moment. The methodology used has been adopted from existing methods for the determination of aflatoxin B1 in food. The food is extracted with an organic solvent followed by immunoaffinity clean-up and reversed-phase high performance liquid chromatography with fluorescence detection. The aim was to select the most suitable method parameters in order to obtain a method that allows the precise determination of aflatoxin B1 in a variety of medicinal herbs. Therefore acetone-water and methanol-water were tested as extraction solvents. Further, the influence of different post-column derivatisation options with electrochemically generated bromine, photochemical reaction and chemical bromination was compared. In addition, two different calculation modes peak height versus peak area were investigated concerning the precision on the evaluation of the rather small peaks that are obtained for aflatoxin B1 at low contamination levels. The different method parameters were applied in the collaborative study to three matrices: senna pods, ginger root and devil’s claw root. As a result, the method with all tested variations was found to be fit-for-purpose for the determination of aflatoxin B1 in medicinal herbs at levels of 1 µg/kg and above. It could be concluded that the tested derivatisation methods had no influence on the analytical result in a range of 1 - 3 µg/kg for aflatoxin B1 in medicinal herbs. This is an interesting conclusion as control laboratories often have a preference for one or the other derivatisation method depending on their experience with one or the other system and its availability. 'A second method was adopted by single-laboratory validation for the determination of aflatoxin B1 in tiger nuts. The interest on tiger nuts rose on the fact of recent entries in the Rapid Alert System for Food and Feed regarding contamination with aflatoxin B1 in tiger nuts. This system allows the European Commission, EU member states and other associated countries to share information and take immediate action when potentially dangerous food or feed is detected on the market or at the border. Additionally a small survey of aflatoxin B1 content in chufa, which is a tiger nuts based soft drink in Spain, was conducted with the adopted method. The detection limit and the quantification limit were 0.02 µg/kg and 0.06 µg/kg respectively. The mean recovery at a level of 2 µg/kg was 88 % (n = 6) and the coefficient of variation 9 %. (II) Development and validation of an analytical method for the determination of zearalenone in infant food as well as in animal feed. The main challenge was to allow the determination of zearalenone at rather low concentrations in infant food, while being also able to deal with complex and more challenging matrices such as compound animal feed, due to their abundant interferences compounds. Previous work performed the determination of zearalenone in cereal grains and at higher levels. The method was validated in an international interlaboratory trial in which laboratories from EU member states, China, Turkey and Uruguay participated. Method performance parameters for both baby food and animal feed were calculated based on results for spiked samples blind duplicates at two levels and based on results for naturally contaminated samples blind duplicates at three levels. Test portions of the samples were spiked at levels of 20 µg/kg and 30 µg/kg zearalenone in baby food and at levels of 100 µg/kg and 150 µg/kg zearalenone in animal feed. As a result the method showed acceptable within-laboratory and between-laboratory precision for each matrix, as required by European legislation. Therefore, the newly developed method allows the enforcement of EU legislative limits for zearalenone in foods for infants at 20 µg/kg. (III) Development and validation of an analytical method for the determination of patulin in juices and purees for infants. The main challenge was to stress the method to determine patulin reliably at levels of 10 µg/kg in products intended for infants and young children. Previously developed methods for patulin were either collaboratively tested at higher levels, indicating that the lower limit for reliable quantification of patulin in such products was around 25 µg/kg or higher, or no validation data except single-laboratory validation were available. Method development focussed on improved and simplified extraction and clean-up procedures. A single liquid-liquid extraction in the presence of sodium sulfate as water binding agent showed sufficient extraction recovery rates for patulin in combination with a solid-phase extraction method, which trapped interfering substances and allowed the purification of patulin extracts without any pre-conditioning of the SPE cartridge. As a result, purees can be extracted without previous enzymatic treatment, as it is required by other methods that use multiple liquid-liquid extractions. Patulin was well separated from the main interfering compound 5-hydroxymethylfurfural during chromatography when using RP-HPLC columns that allow the separation of rather polar substances with mobile phases of more 99% of water. Additionally to this method A and due to the large number of laboratories that intended to participate in the validation process, the participants were split into two groups and a second method B was validated. This method B is a slightly modified version with the same principle as the one previously published by MacDonald et al. in 2000. The main modifications related to the aliquotation. Patulin is extracted three times from the juice or the de-pectinated puree with neat ethyl acetate. The combined ethyl acetate phases were re-extracted with sodium carbonate solution and evaporated. The residue was then re-dissolved in 0.1 % acetic acid solution and separated by HPLC as in method A. Both methods were tested for the determination of patulin in apple juice and fruit puree at the proposed European regulatory limit of 10 µg/kg. The methods were validated in an international interlaboratory trial in which laboratories from EU Member States, Japan and Brazil participated. Method performance parameters for both apple juice and fruit puree were calculated based on results for spiked samples blind duplicates at two levels and based on results for naturally contaminated samples blind duplicates at three levels for both methods. Test portions of the samples were spiked at levels of 10 µg/kg and 25 µg/kg patulin for both apple juice and fruit puree. In conclusion, the new developed method A showed acceptable within-laboratory and between-laboratory precision for both juice and puree at all levels, while method B only fulfilled partially the performance parameters as required by current EU legislation. Therefore, the newly developed method allows the enforcement of EU legislative limits for patulin in foods for infants at 10 µg/kg. Finally the development and in-house validation of a method for determination of patulin using ultra high pressure liquid chromatography in combination with a mass selective detector, resulting in a better chromatographic and analyte selective separation within a shorter time is described. This is of interest especially for projects in which larger amounts of results need to be generated. A survey with more than 200 samples of baby foods, apple purees and tomato purees from the EU food market was performed with this method. It indicated that during the period of 2006 almost all products were free of patulin and all products were compliant with current EU legislation

    Tendències en l'alimentació : Alimentària 2006

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    Actualment, l'alimentació ofereix als consumidors moltes més opcions que fa uns anys. Aquesta ràpida evolució respon a la necessitat d'adaptació d'aquest sector al trepidant ritme de vida que pateix la nostra societat. La indústria desenvolupa aliments més atractius, pràctics i durables, però també d'altres amb característiques que busquen el tan desitjat benestar a través de determinats ingredients. A la vegada es promou la dieta mediterrània com a patró alimentari saludable, ja que s'hi troben infinitat de substàncies amb reconeguts beneficis per a la salut. La informació sobre tot això arriba de fonts molt diverses i no sempre el missatge és el mateix.Currently food gives the consumers more options than some years ago. This speedy evolution is the response of an adaptation need that this sector has because of the fast rhythm of live in our society. The industry develops more attractive, useful and durable foods, but also some of them with added ingredients to look for the desirable well-being. At the same time, a mediterranean diet promotion is ongoing, like a healthy dietary pattern, because the presence of some substances with a recognized health benefit. Information about it arrives from several sources and the message is not always the same

    Propuesta de indicadores de rendimiento para bibliotecas móviles

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    It’s necessary the evaluation to go to the better management of all library services. The performance indicators are very important elements for it. However bookmobiles work with some non-library factors that are very outstanding for your management. The article is a proposal of performance indicator only for bookmobiles from the adaptation of ISO 11260. Information and Documentation. Library performance indicators, where it make into account the conjunction of library with non-library elements

    Alcoholic beverages as determinants of traffic fatalities

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    The most important contribution of this research lies in considering the impact of wine, beer and liquors on the ratio of traffic fatalities because each kind of alcoholic beverage is characterized by different ethanol content. The data, drawn for case of Spain, validate our theoretical hypothesis. Our findings support the strategy of incrementing alcohol taxes in order to reduce the negative externalities of alcohol abuse. However, it is necessary to implement non-economic policies because of the existence of collateral effects (positive crossed price elasticities)

    El derecho de huelga en los servicios esenciales de la comunidad

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    El derecho a huelga en los servicios esenciales para la comunidad se halla escasamente regulada siendo una "anomalía jurídica" [...]Grado en Relaciones Laborales y Recursos Humano

    La inclusión del niño superdotado en el aula

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    Breve recorrido sobre la evolución de los estudios de superdotación, en los que se verá como se identifica, características y tratamiento de los alumnos en el aula. Toda esta información sirve para crear un caso práctico que hace referencia a la inteligencia emocional.Grado en Educación Primari

    La cadena de valor de semillas Columbia, S.A.

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    En este trabajo hemos utilizado la herramienta conocida como Cadena de Valor de Porter para detectar y analizar las actividades y eslabones que más valor generan a la empresa Semillas Columbia, S.A. Empresa dedicada a la producción y comercialización de semilla certificada. Por último hemos realizado una serie de propuestas para el desarrollo futuro de la empresa.Grado en Administración y Dirección de Empresa

    Participación de las IL-6 y moléculas relacionadas en la Fisiopatología de la superficie ocular: Consecuencias de su silenciamiento genético

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    Se ha estudiado la participación de la IL-6 en diferentes procesos inflamatorios de la superficie ocular, basados en estimulación con citoquinas, cicatrización y estimulación con sobrenadantes bacterianos. Además, se ha propuesto una aproximación de terapia génica, empleando nanopartículas y siRNA. Los resultados obtenidos demuestran que las células epiteliales de la córnea pueden iniciar una respuesta inflamatoria en respuesta a estímulos como IL-6, IL-17 o sobrenadantes bacterianos. Las células epiteliales corneales experimentaron una cicatrización acelerada en presencia de IL-6, atenuada al coestimular con IL-10. Se ha demostrado por primera vez que el receptor A de la IL-17 se expresa en los tejidos de la superficie ocular humana. Finalmente, se ha comprobado que determinadas nanopartículas preparadas a partir de gelatina cationizada son sistemas eficaces para vehiculizar el siRNA al interior de las células epiteliales corneales. Sin embargo, la aproximación terapéutica basada en el silenciamiento de citoquinas proinflamatorias mediante siRNA necesita ser reconsiderada

    Nuevos modos de habitar / nuevos modelos de convivencia

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    El presente documento va dirigido a la realización del proyecto de Fin de Carrera de la Escuela Técnica Superior de Arquitectura de la Universidad de Valladolid. Bajo el planteamiento de “nuevos modos de habitar/ nuevos modelos de convivencia”, se propone la realización de un proyecto de viviendas que parte de la investigación sobre los nuevos modelos de convivencia y las respuestas a los problemas heredados de la vivienda moderna. De acuerdo al enunciado del proyecto, en la última década y provocado por la crisis financiera de 2008, lo colectivo comienza a ser un factor importante y empiezan a desarrollarse “nuevos modelos de convivencia” que desarrollan y amplían el concepto de cooperativa. El programa plantea proyectar un conjunto de unas 75 viviendas, de distintos tamaños y variadas organizaciones espaciales, con nuevas soluciones tipológicas para colectivos diferentes y que tengan que ver con la actual realidad social.Departamento de Teoría de la Arquitectura y Proyectos ArquitectónicosMáster en Arquitectur
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