1,721,080 research outputs found
Classification and adulteration control of vegetable oils based on microwave reflectometry analysis
No full textOlive oil production represents a big part of the Mediterranean economy, and as such it must be protected from frauds. For this reason, it is necessary to develop alternative low-cost techniques, applicable on large scale, for checking the quality of the product and for detecting adulteration. On such bases, the present work deals with the possibility of adopting microwave reflectometry for obtaining a 'spectral signature' of vegetable oils. For this purpose, time domain reflectometry (TDR) measurements, in combination with specific data processing, are first used for the dielectric characterization of several oil types. Successively, the acquired data are processed through the principal component analysis (for identifying clusters of oil types that exhibit common features) and through the partial least square analysis (for identifying a predictive model for detecting oil adulteration). Results confirm that the proposed procedure holds considerable potential for quality and anti-adulteration control purposes, especially in view of practical applications. (C) 2012 Elsevier Ltd. All rights reserved
Extending industrial applicability of TDR liquid level monitoring through flexible probes
No full textIn the present work, an alternative probe configuration to be used for time domain reflectometry (TDR)-based monitoring of liquid level inside tanks is presented. The proposed probe, which resorts to a bifilar transmission line configuration, is flexible and adaptable to the surface of the containers to be monitored. This feature, along with the other advantageous characteristics of TDR, makes this probe configuration particularly attractive for industrial applications. In this paper, to test the applicability of the method, two different scenarios are considered: monitoring of liquids contained in metallic tanks and non-invasive monitoring of liquids in non-metallic tanks. Results show that, in both cases, the proposed system has considerable potential for being easily and effectively employed in practical, industrial applications
Characterization of Bronze age pottery from the Grotte di Pertosa-Auletta (Italy): Results from the first analysis of organic lipid residues
No full textThe “Grotte di Pertosa-Auletta” are a karst cavity complex located in Pertosa (Salerno, Italy), that opens in the Tanagro valley with a large entrance, about 15 m wide and 17 m high, oriented towards the west. The caves are a very important prehistoric site because they preserve the remains of a pile-dwelling village dating back to the II millennium BC. Different types of ceramic finds, coming from the so-called “antegrotta”, have been selected and submitted to chemical investigations, with the aim of verifying the possible presence of organic residues and identifying their nature. Both Gas Chromatography/Mass Spectrometry (GC–MS) and the Gas Chromatography/Combustion/Isotope Ratio Mass Spectrometry (GC-C-IRMS) have been used to identify lipids absorbed by the ceramics and to formulate hypotheses about artefact uses and functions. Most of the finds have shown the presence of lipids of animal origin: these are mixtures of lipids of ruminant and non-ruminant animals, while in a single sample the isotopic analyses have identified the presence of dairy/milk products. Data shed light on the use and the human activities of the cavity of the “Grotte di Pertosa-Auletta” during the Bronze Age, and they constitute one of the few examples in Italy of chemical analysis applied to the ceramic residues of similar archaeological contexts
Dielectric Spectroscopy of Liquids Through a Combined Approach: Evaluation of the Metrological Performance and Feasibility Study on Vegetable Oils
No full textIn this work, a time domain-based approach for the estimation of the dielectric parameters of liquids is presented. The proposed approach combines traditional time-domain reflectometry measurements with a specific data processing and modeling that leads to the evaluation of the Cole-Cole parameters. The pivotal step of the procedure is the implementation of an accurate transmission line model of the used measurement cell. In this way, the error contributions due to undesired parasitic effects are minimized; hence, the overall accuracy is significantly enhanced. The proposed approach is tested through repeated measurements on well-referenced materials; this also allowed performing the related metrological analysis. Successively, the proposed procedure is applied for the evaluation of the Cole-Cole parameters of vegetable oils. In fact, at the state-of-the-art, only limited data are available for the dielectric characteristics of vegetable oils. In particular, ten different types of vegetable oils are considered. Results show that the proposed approach has strong potential also for possible practical applications in the area of anti-adulteration and quality control
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
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
Insights into Plastic Degradation Processes in Marine Environment by X-ray Photoelectron Spectroscopy Study
Full text linkThe present study employs X-ray photoelectron spectroscopy (XPS) to analyze plastic samples subjected to degradation processes with the aim to gain insight on the relevant chemical processes and disclose fragmentation mechanisms. Two model plastics, namely polystyrene (PS) and polyethylene (PE), are selected and analyzed before and after artificial UV radiation-triggered weathering, under simulated environmental hydrodynamic conditions, in fresh and marine water for different time intervals. The object of the study is to identify and quantify chemical groups possibly evidencing the occurrence of hydrolysis and oxidation reactions, which are the basis of degradation processes in the environment, determining macroplastic fragmentation. Artificially weathered plastic samples are analyzed also by Raman and FT-IR spectroscopy. Changes in surface chemistry with weathering are revealed by XPS, involving the increase in chemical moieties (hydroxyl, carbonyl, and carboxyl functionalities) which can be correlated with the degradation processes responsible for macroplastic fragmentation. On the other hand, the absence of significant modifications upon plastics weathering evidenced by Raman and FT-IR spectroscopy confirms the importance of investigating plastics surface, which represents the very first part of the materials exposed to degradation agents, thus revealing the power of XPS studies for this purpose. The XPS data on experimentally weathered particles are compared with ones obtained on microplastics collected from real marine environment for investigating the occurring degradation processes
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