1,998 research outputs found
Detection of equine atypical myopathy-associated hypoglycin A in plant material: Optimisation and validation of a novel LC-MS based method without derivatisation
Hypoglycin A (HGA) toxicity, following ingestion of material from certain plants, is linked to an acquired multiple acyl-CoA dehydrogenase deficiency known as atypical myopathy, a commonly fatal form of equine rhabdomyolysis seen worldwide. Whilst some plants are known to contain this toxin, little is known about its function or the mechanisms that lead to varied HGA concentrations between plants. Consequently, reliable tools to detect this amino acid in plant samples are needed. Analytical methods for HGA detection have previously been validated for the food industry, however, these techniques rely on chemical derivatisation to obtain accurate results at low HGA concentrations. In this work, we describe and validate a novel method, without need for chemical derivatisation (accuracy = 84–94%; precision = 3–16%; reproducibility = 3–6%; mean linear range R2 = 0.999). The current limit of quantitation for HGA in plant material was halved (from 1μg/g in previous studies) to 0.5μg/g. The method was tested in Acer pseudoplatanus material and other tree and plant species. We confirm that A. pseudoplatanus is most likely the only source of HGA in trees found within European pastures
Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: Relevance of their surface active properties and of the type of emulsifier
The antioxidant activity of gallic acid and a series of alkyl gallates (C4-C18) and glycosylated alkyl gallates (C4-C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behavior of the antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin or Tween-20, indicating the greater relevance of having three OH groups at the polar head in comparison with having improved surfactant properties but just a di-ortho phenolic structure in the antioxidant
Convergencia mediática digital : el uso y consumo de los nuevos medios por mujeres catalanas
El consumo y la dinámica de las pantallas de comunicación han experimentado en el mundo un
marcado aumento en los últimos años y los medios de comunicación tradicionales, con sus
gramáticas y mercados perfectamente definidos, han evolucionado como consecuencia del
protagonismo de Internet. La convergencia mediática reduce la distancia entre el emisor y el
receptor, desapareciendo así la unidireccionalidad y desarrollando una comunicación horizontal
que deja la pasividad, ya que el receptor adopta una actitud activa. En este artículo se dibuja el
consumo de contenidos que realizan las mujeres en Cataluña, y cuál es el soporte utilizado en el
marco de la convergencia mediática digital. Se describen los resultados obtenidos a raíz de
combinar 6 grupos de discusión con 6 entrevistas en profundidad en dos grupos segmentados de
la población en función de la edad y su formación: grupo infantil y juvenil. Se ha dado prioridad a
los colectivos infantil y juvenil porque son los que marcan de forma influyente las tendencias a
medio plazo, los que se han socializado con una serie de soportes que no existían anteriormente
y los que son más polivalentes en el uso de los diversos soportes disponibles en el mercado. La
población adulta no ha sido examinada en el estudio porque posee determinadas barreras de
entrada, como la falta de competencias técnicas para el uso de los nuevos dispositivos
On the convergence of multi-level Hermite-Pad\'e approximants
In the present paper we prove a Stieltjes type theorem on the convergence of
a sequence of rational functions associated with a mixed type Hermite-Pad\'e
approximation problem of a Nikishin system of functions and analyze the ratio
asymptotic of the corresponding Hermite-Pad\'e polynomials.Comment: 24 page
Consumo de Medios Digitales por niños y preadolescentes en Cataluña, España
The focus of this study is patterns of use of digital media, which are the most popular platforms
and what control that parents impose on the consumption of digital media. We analyzed
children aged between 7 and 10 years old and pre-teenagers aged between 11 and 12
years old. These groups are those who influence the medium-term trends. The results show
that digital media are present in the everyday life of children, who regularly consume their
preferred contents. They can be powerful if they can recognize and use their power in this
culture of convergence as users.El objetivo este estudio es conocer los patrones de uso de los medios digitales, las plataformas
más usadas y entender los controles parentales que se ejercen sobre niños de entre 7 y
10 años y preadolescentes de entre 11 y 12 años, los grupos que serán influenciados a medio
plazo por las nuevas tendencias. Los resultados muestran que los medios digitales están presentes
en la vida cotidiana de los niños, que consumen regularmente sus contenidos preferidos.
Estos resultados pueden ser de gran alcance si es posible reconocer y utilizar su poder
como usuarios en esta cultura de la convergencia digital
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