1,720,988 research outputs found
Application of an Eco-sustainable technology: use of direct and photodynamic UV light for the microbial inactivation in food industries
No full textThis study investigates visible light, particularly blue light (BL), as a sustainable, non-thermal, and chemical-free approach for microbial inactivation in food settings. The research initially focuses on utilizing endogenous photosensitizers (PS) within bacterial cells, optimizing treatment parameters, and determining effective dose ranges. Experiments were conducted on substrates like agar, liquid media, and mature biofilms to mimic real-world food-related conditions.
Tests conducted on agar and liquid substrates highlighted the greater susceptibility of Gram (+) bacteria compared to Gram (-) bacteria. However, variability was observed even within the same bacterial class, probably due to differences in the quantity, type, and intracellular localization of the PS, as well as to the bacteria's specific oxidative stress response mechanisms. Biofilms were cultivated over periods of 5 and 13 days on different surfaces, and their reduction, along with morphological changes post-irradiation, was validated using CLSM. The findings consistently demonstrated that lower BL wavelengths (405 nm) exhibit greater antimicrobial efficacy than higher wavelengths (450 nm).
The research also compared 365 nm (UVA) and 405 nm (BL) wavelengths to examine their effects on Reactive Oxygen Species (ROS) production, known to mediate cellular damage and death during light irradiation. Lipid peroxidation and membrane permeabilization were assessed, revealing that additional ROS-mediated mechanisms contribute to microbial inactivation. In partnership with Electrolux Italia S.p.A., a moke-up system for 365 nm and 405 nm light irradiation was developed and optimized for potential use in consumer appliances. The system was evaluated for irradiance uniformity, light dose, microbial inactivation, and energy efficiency. Results showed consistent microbial inactivation across both wavelengths at room and refrigerated temperatures, with light dose emerging as the critical factor for effective treatment.
The study further explored exogenous photosensitizers (PS) in solution, using Methylene Blue (MB) as a synthetic PS and curcumin as a natural alternative. Experiments with MB revealed that factors like liquid substrate characteristics and microbial gram type significantly impacted the required PS concentration. Curcumin showed high microbial reduction efficacy for both Gram (+) and Gram (-) bacteria, albeit with differing kinetic profiles. Monochromatic light enabled efficient microbial inactivation using low PS concentrations and minimal light doses, demonstrating its effectiveness.
The study examined 4MeP porphyrin at 5% and 10% concentrations, supported in a vanillin-based material, Valpol. Results showed that Gram (+) bacteria required a lower light dose for effective inactivation at equivalent PS concentrations. Reusing the material improved microbial inactivation as pores formed, increasing PS exposure to light. Interestingly, the relationship between higher PS content and microbial inactivation was non-linear.
This thesis explores light-based technologies for the food sector, emphasizing their practical applications and technological transfer for implementation. Key factors for effective use include light dose, microbial type, wavelength, and substrate characteristics. The study highlights the need to tailor conditions to specific applications for successfully deploying light-based treatments in food contexts
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
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