1,720,966 research outputs found
Reduction of beauvericin and enniatins bioaccessibility by prebiotic compounds, evaluated in static and dynamic simulated gastrointestinal digestion
No full textThe aim of this study was to investigate the bioaccessibility of beauvericin (BEA) and enniatins (ENs) present in wheat crispy breads. A microbial fermentation was performed by a BEA- and ENs-producer Fusarium strain, adding inulin and fructooligosaccharides (FOS) at two concentrations (1% and 5%). The bioaccessibility of mycotoxins was determined by static and dynamic simulated gastrointestinal digestion systems, imitating the digestive physiological conditions until the colonic compartment. BEA and ENs were determined in the intestinal fluids by liquid chromatography-tandem mass spectrometry (LC-MS/MS). BEA and ENs bioaccessibilities in the static model (46.7-61.1% and 6.2-44.9%, respectively) were lower than those found in the dynamic one (76.2-91.0% and 23.0-68.9%, respectively). Addition of inulin and FOS decreased the bioaccessibility of BEA and ENs, with a concentration-dependent behavior, thus being a potential strategy to reduce human exposure to these minor mycotoxins
Analysis of Chlorpyrifos in Water, Fruit juices and Honeybee Extracts by Chemiluminescent ELISA
No full textThe suitability of competitive enzyme-linked immunosorbent assays (ELISAs) with chemiluminescent detection based immobilized antigen (indirect assay) for rapid an accurate determination of chlorpyrifos in different food matrices was tested. The limit of detection (LOD) value were between 1-1.75 ng ml-1, the standard curve midpoint (IC50) was 3.5 ng ml-1, and assay duration was 1.5 h. Assay application to the analysis of honeybees extract resulted in chlorpyrifos recoveries varying between 62 and 83 % in 5-15 ng ml-1 herbicide concentration range
Simultaneous determination of eight underivatized biogenic amines in fish by solid phase extraction and liquid chromatography-tandem mass spectrometry
Full text linkBiogenic amines on fish tissue are formed as a result of bacterial contamination and spoilage during storage.
A new method based on liquid chromatography (LC) and tandem mass spectrometry (MS/MS) using
a triple quadrupole (QqQ) analyser was developed for the analysis of eight biogenic amines (cadaverine,
histamine, phenylethylamine, putrescine, spermine, spermidine, tyramine and tryptamine) in fish tissues.
Sample preparation was performed by extraction with trichloroacetic acid 5% and solid phase
extraction clean up with STRATA X cartridge. The MS/MS method was validated and compared with a
method based on the analysis of dansyl derivatives by LC and fluorescence detector (FD). MS/MS achieved
higher sensitivity (from 0.02 mg kg1 for spermidine and phenylethylamine to 0.2 mg kg1 for spermine)
when compared to FD (from 1 mg kg1 for putrescine and tyramine to 4 mg kg1 for histamine); MS/MS
method showed higher precision too, with intraday relative standard deviations (RSDs) from 1% to 4%
with respect to those obtained with FD method (from 3% to 17%).
Recovery study was conducted at two different fortification levels and the average ranged from 71% to
93% for all of the studied compounds with RSDs lower than 18%. Matrix-matched standards were used to
counteract matrix effect observed in MS/MS determination. The applicability of the method was demonstrated
by the analysis of biogenic amines in fish obtained from commercials of Valencia
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bioaccesibilidad de la micotoxina beauvericina mediante sistemas dinámicos y estáticos
No full textLa evaluación del riesgo toxicológico conlleva en su etapa de exposición el establecimiento de la duración, frecuencia y magnitud de la exposición a un contaminante químico. Cuando son los alimentos la vía de entrada del contaminante, la evaluación de la magnitud de la exposición al tóxico debería llevarse a cabo considerando la biodisponibilidad oral, es decir la “fracción de una dosis administrada que alcanza el compartimento central (sangre) desde el tracto gastrointestinal” , también conocida con el término de biodisponibilidad absoluta. Una herramienta conservativa para evaluar la biodisponibilidad oral es la bioaccesibilidad oral, definida como “la fracción soluble en el tracto gastrointestinal que está disponible para su absorción”.
En el siguiente estudio se ha evaluado la bioaccesibilidad de la micotoxina menor de Fusarium beauvericina (BEA) contenida en galletas artesanales contaminadas con Fusarium proliferatum productor de este compuesto bioactivo. El proceso de digestión gastrointestinal se simuló mediante un sistema dinámico constituido por un biofermentador y un sistema estático en los cuales se han simulado los diferentes compartimientos digestivos como la boca, el estómago, el intestino delgado y el intestino grueso. El análisis de la BEA en los diferentes fluidos intestinales se realizó mediante la técnica de la cromatografía líquida asociada a la detección con espectrometría de masas.
Mediante el sistema de fermentación dinámico la bioaccesibilidad media evidenciada por la micotoxina beauvericina fue del 67%, mientras que utilizando el sistema estático no se evidenciaron diferencias significativas con el modelo dinámico.
La aplicación de los modelos estáticos y dinámicos ha permitido caracterizar la bioaccesibilidad de la micotoxina menor de Fusarium BEA mejorando sin duda el análisis del riesgo asociado a alimentos contaminados con este compuesto bioactivo producido por el género Fusarium
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
