1,721,144 research outputs found
Nanostructured quartz crystal microbalances for gas sensing based on metal nanoparticles decorated with peptides. the role of nanomaterial and peptide design for the realization of gas sensor arrays
No full textAromatic compounds and food patterns have a key role in traceability and quality control of foods. Noninvasive test methods based on the qualitative/quantitative estimation of flavors pattern using sensors are a valuable tool for the food industry. The use of an array of sensors, as in electronic noses (e-noses), has the potential to assay multiple samples quickly and easily. The use of peptides as binding elements in this types of sensors has been demonstrated to be very useful the recognition of different classes of volatile compounds. In order to improve recognition peptides are conjugated to nanoparticles (NPs). In this work we report data obtained using different peptides. designed "in silico" immobilized onto AuNPs or ZnONPs and deposited on quartz crystal microbalances. We found different behavior for the detection of samples with high content of water using AuNPs prepared with different methods and ZnONPs. The sensor arrays based on ZnONPs and AuNPs conjugated with peptides were able to discriminate pure aroma compounds allowing to perform headspace analysis in minutes. Measurement using ZnONPs allowed measurement in water mixtures without drift of the signal and acceptable standard deviations (intraday below 20%). This approach represents a rapid and low-cost method to evaluate volatile patterns in food
Study on volatile markers of pasta quality using GC-MS and a peptide based gas sensor array
No full textHeadspace GC-MS (gas chromatography-mass spectrometry) and peptide based gas sensor array (E-nose) analysis were performed to evaluate the volatile fraction of durum wheat pasta samples of different commercial value and furosine content. A clear discrimination among high-price and low price samples of pasta was achieved using a simple PCA (Principal Component Analysis) of GC-MS dataset. This was attributed to the quality of semolina used in the process. Linear discriminant analysis (LDA) allowed discrimination among low or high furosine content in the samples. The peptide based a-nose was tested initially on a set of pure key volatiles found in GC-MS analysis and then on pasta samples. Discrimination of pasta samples having different commercial value was achieved. This work demonstrates that volatiles can be used to determine the quality of pasta with respect to semolina and thermal treatment. Moreover, the peptide-based e-nose represents a useful tool alternative to GC-MS to detect off-flavours and quality of the semolina in pasta
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
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
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