1,720,957 research outputs found
Estudio teórico y experimental del proceso de conservación de productos naturales renovables
Get PDFTesis (DCI)--FCEFN-UNC, 2020Fil: Raspo, Matías Alejandro. Universidad Tecnológica Nacional. Regional San Francisco; Argentina.La generación de envases biodegradables con el agregado de principios activos es una de las tecnologías que se encuentran en constante estudio en diferentes campos de investigación e industrias. El objetivo de esta tesis fue la generación de un nuevo tipo de recubrimiento biodegradable a base de quitosano, con la incorporación de ácido gálico como compuesto bioactivo puro, o de aceites esenciales derivados de cítricos, como mezclas de compuestos bioactivos. Las películas sintetizadas a partir de la evaporación de agua fueron caracterizadas mediante ensayos antioxidantes, antimicrobianos, mecánicos, fisicoquímicos y espectroscópicos. La optimización de la obtención de un recubrimiento con las características buscadas fue lograda a partir de la implementación de modelos de superficie de respuesta, y la optimización de las condiciones experimentales para la formación de las películas. Además, se realizaron pruebas incipientes a escala laboratorio sobre ensayos de biodegradabilidad y aplicabilidad para la conservación de tomates tipo cherry.Fil: Raspo, Matías Alejandro. Universidad Tecnológica Nacional. Regional San Francisco; Argentina
Antioxidant and antimicrobial properties of starch-citric acid-glycerol films
No full textPotato starch films incorporated with citric acid as active compound and glycerol as plasticizers wereevaluated in their antimicrobial and antioxidant properties. Characterization of the films revealed notable transparency and smoothness, often accompanied by a yellowish hue attributed to the Maillard reaction. Antimicrobial assays demonstrated activity against Staphylococcus aureus ATCC 25923. Response surface analysis indicated that starch concentration significantly influenced antioxidant responses, with citric acid enhancing the antimicrobial properties.These findings highlight the potential of citric acid enhanced starch films for eco-friendly packaging, contributing to the development of functional and sustainable materials.Fil: Raspo, Matías Alejandro. Universidad Tecnológica Nacional. Facultad Reg.san Francisco. Departamento de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Villa María; ArgentinaFil: Vignola, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Reg.san Francisco. Departamento de Ingeniería Química; ArgentinaFil: Andreatta, Alfonsina Ester. Universidad Tecnológica Nacional. Facultad Reg.san Francisco. Departamento de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Optimization of antioxidant, mechanical and chemical physical properties of chitosan-sorbitol-gallic acid films by response surface methodology
Get PDFThe interest in the development of biodegradable films is increasing, which is related to the wide availability of resources and methods of synthesis to generate them. For this reason, in this study, the preparation of films containing chitosan, sorbitol and gallic acid this study was proposed. The incorporation of natural antioxidants into films modifies their structure and provides new functionality to them. In order to determine the optimal content of sorbitol and gallic acid in the formulation of the chitosan films to obtain the highest antioxidant capacity and the best mechanical properties, an experimental design based on a two-factor Doehlert model was used. The optimum condition of film synthesis was obtained when a mixture of 1 wt chitosan, 3.62 wt% of sorbitol and 1 wt% of gallic acid was performed. The properties studied were experimentally evaluated at this optimal point and compared with the model predictions, showing good results. It proved to be a promising material to be successfully used as packaging material.Fil: Raspo, Matías Alejandro. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; ArgentinaFil: Gomez, Cesar Gerardo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Andreatta, Alfonsina Ester. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentin
Antioxidant and antimicrobial activities of citrus essential oils from Argentina and the United States
No full textPeels of citrus species from Argentina and the United States were subjected to hydrodistillation to obtain their essential oils. Gas chromatography/mass spectrometry was carried out to determine the chemical composition of all the essential oils. Limonene was found as the major compound with many minor components varying according to the different species. Antioxidant assays were done to determine the antioxidant activities of essential oils. The antimicrobial activity was tested against Leuconostoc mesenteroides MS1, Escherichia coli ATCC 25922 and Lactobacillus plantarum ES147 and ATCC 8014. Mandarin essential oil from the USA showed the strongest antioxidant capacity in different assays. Grapefruit and lemon essential oils showed consistently strong antimicrobial activity against all tested bacteria, so they were selected for determining the minimum inhibitory concentration and minimum bactericidal concentration values against E. coli ATCC 25922 . Minimum inhibition concentration values ranged between 0.33 and 0.55 mg/mL and minimum bactericide concentration values ranged between 0.42 and 0.95 mg/mL.Fil: Raspo, Matías Alejandro. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Vignola, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Andreatta, Alfonsina Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Juliani, Héctor Rodolfo. Rutgers University; Estados Unido
Antioxidant and antimicrobial activity of bioactive chitosan films
Get PDFIn this work the preparation of chitosan films containing different bioactive compounds (gallic acid or salicylic acid) and plasticizers (sorbitol or Tween 80) was assessed. In addition, the component composition influence on the performance of chitosan based films over antimicrobial and antioxidant activity were researched using the Response Surface Methodology from a Doehlert two-factor model. Both films (A: chitosan/gallic acid/Tween 80 and B: chitosan/ salicylic acid/sorbitol) showed a good antioxidant capacity where a higher bioactive compound content and a low plasticizer concentration led to the best performance. Furthermore, the chitosan/gallic acid/Tween 80 film evidenced antimicrobial activity against Escherichia coli ATCC 25922. Chitosan-based films developed from formulation A and B showed a promising performance as bacteriostatic agent, which is sufficient evidence to assess these films as successful materials for food packaging.Fil: Raspo, Matías Alejandro. Universidad Tecnológica Nacional. Facultad Regional San Francisco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vignola, María Belén. Universidad Tecnológica Nacional. Facultad Regional San Francisco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Gomez, Cesar Gerardo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Andreatta, Alfonsina Ester. Universidad Tecnológica Nacional. Facultad Regional San Francisco; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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