65 research outputs found

    Evaluación de la migración de bromuro de cetilpiridinio desde nanocompósitos activos hacia un simulante graso de alimentos/Cetylpyridinium bromide migration assessment from active nanocomposites to a fatty food simulant

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    En los últimos años, el desarrollo de nanocompósitos poliméricos se plantea como una interesante alternativa para el diseño de nuevos materiales para el envasado activo de alimentos. A pesar de esto, existe constante preocupación relacionada a la migración de los componentes activos incorporados en el material ya que, un material de envasado destinado a entrar en contacto con un alimento debe presentar valores de migración bajo los límites establecidos en regulaciones internacionales. En este sentido, el objetivo del presente trabajo fue evaluar la migración del surfactante bromuro de cetilpiridinio (CPB) desde nanocompósitos activos de polietileno de baja densidad y montmorillonita modificada con CPB, hacia un simulante graso de alimentos (etanol 95 %). El seguimiento de la migración del componente se realizó a través de la medición de la conductividad eléctrica del simulante en contacto con los nanocompósitos. Se determinó que la presencia del 3,0 % de organoarcilla permite una mayor migración del CPB debido a la presencia del surfactante libre en la matriz y al hinchamiento de la organoarcilla superficial por hidratación. Además, se observó que la migración es prolongada en el tiempo y está por debajo de los límites permitidos por la legislación estadounidense, lo que permitiría la generación de materiales novedosos que podrían ser empleados en el diseño de envases activos de alimentos. In the last years, the development of polymeric nanocomposites is presented as an interesting alternative for the design of new materials for active food packaging. Despite this, there are concerns regarding the migration of the components incorporated in the material since a packaging material intended to come into contact with food must have migration values under the limits established in international regulations. In this sense, the aim in this work was to evaluate the migration of the surfactant cetylpyridinium bromide (CPB) from active nanocomposites of low density polyethylene and motmorillonite modified with CPB to a fatty food simulant (ethanol 95 %). The migration of the component was followed by fat simulant electrical conductivity measurements during the contact with the nanocomposites. It was determined that materials with 3,0 % of organoclay allowed a higher migration of CPB due to the presence of free surfactant in the matrix and swelling of the superficial organoclay. In addition, it was observed that the migration is prolonged in time and it is below the limits allowed by US legislation, which would enable the generation of novel materials that could be used in the design of active food packaging. Palabras clave: surfactante, conductividad eléctrica, polietileno de baja densidad, organoarcilla, envase activo de alimentos. Keywords: surfactant, electrical conductivity, low density polyethylene, organoclay, food active packaging

    Obtention of Antimicrobial Fibers Type Core/Shell PLA/PVOH-LAE by Coaxial Electrospinning

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    Coaxial electrospinning (EC) is a technology that allows the encapsulation of active compounds, as ethyl lauroyl arginate (LAE), in shell/core structures, in order to develop new antimicrobial food packaging materials with slowdown of active compound´s release with the purpose of extending food shelf life. For this reason, the objective of this study consisted in developing antimicrobial fibers shell/core type by EC. Two polymers with different hydrophilic character as poly (lactic acid) (PLA) to the shell and poly (vinyl alcohol) (PVOH) and LAE to the core were used to obtain PLA/PVOH-LAE fibers, and slowdown the release of antimicrobial compound. The morphology of fibers was evaluated by optical microscopy and the thermal properties through thermogravimetric analyses (TGA). Release studies were carried out in fatty (ETOH 95%) food simulant and was compared with the minimum inhibitory concentration (MIC) values of LAE against Listeria innnocua. The optical micrographs evidenced the obtention of shell/core structure with an average diameter of 0,6 µm approximately, and the TGA analyses demonstrated the thermal protection of LAE by shell of fibers. Released LAE reached the equilibrium state in ETOH 95% during the first 3 hours, maintaining a higher concentration than MIC value obtained in L. innnocua (10 ppm). The results demonstrate that new packaging materials with antimicrobial activity as PLA/PVOH-LAE polymeric fibers with shell/core structure can be obtained through coaxial electrospinning technique. Keywords: coaxial electrospinning, ethyl lauroyl arginate, fibers, shell/core, food packaging. Resumen El electrohilado coaxial (EC) es una tecnología que permite encapsular compuestos activos como el etil lauroil arginato (LAE) en estructuras tipo pared/núcleo con la finalidad de desarrollar nuevos materiales antimicrobianos para el envasado de alimentos que ralenticen la liberación del compuesto y extiendan la vida útil del alimento. Por tal razón, el objetivo de este estudio consistió en desarrollar fibras antimicrobianas tipo pared/núcleo mediante EC. Dos polímeros con distinto carácter hidrofílico como el poli (ácido láctico) (PLA) para la pared y poli (alcohol vinílico) (PVOH) y LAE para el núcleo se utilizaron para obtener las fibras PLA/PVOH-LAE, y ralentizar la liberación del compuesto antimicrobiano. La morfología de las fibras se evaluó mediante microscopía óptica y sus propiedades térmicas mediante análisis termogravimétricos (TGA). Se realizaron estudios de liberación del LAE en un simulante de alimentos graso (ETOH 95%), y se comparó con la concentración mínima inhibitoria (MIC) hacia una bacteria Gram positiva Listeria innnocua. Las micrografías ópticas evidenciaron la obtención de la estructura pared/núcleo con un diámetro promedio de 0,6 µm aproximadamente, y el análisis TGA demostró la protección térmica del LAE por la pared de las fibras. El LAE liberado alcanzó el estado de equilibrio en ETOH 95% durante las 3 hr iniciales, manteniendo una concentración superior a la MIC obtenida para L. innnocua (10 ppm). Los resultados demuestran que nuevos materiales de envase con actividad antimicrobiana como fibras poliméricas PLA/PVOH-LAE con estructura pared/núcleo pueden ser obtenidos mediante la técnica de electrohilado coaxial. Palabras clave: electrohilado coaxial, etil lauroil arginato, fibras, pared/núcleo, envase de alimentos

    Obtention of Antimicrobial Fibers Type Core/Shell Pla/Pvoh-Lae By Coaxial Electrospinning

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    Coaxial electrospinning (EC) is a technology that allows the encapsulation of active compounds, such as ethyl lauroyl arginate (LAE), in shell/core structures, in order to develop new antimicrobial materials for food packaging that slow down the release of active compounds and extend the food’s shelf life. For this reason, the objective of this study was to develop antimicrobial fibers shell/core type by EC. Two polymers with different hydrophilic character, polylactic acid (PLA) for the shell and polyvinyl alcohol (PVOH) and LAE for the core, were used to obtain PLA/PVOH-LAE fibers and slow the release of the antimicrobial compound. The morphology of fibers was evaluated by optical microscopy and their thermal properties through thermogravimetric analyses (TGA). LAE release studies were carried out in a fatty food simulant (ETOH 95%), and was compared with the minimum inhibitory concentration (MIC) values of LAE against a gram-positive bacteria, Listeria innnocua. The optical micrographs showed the obtaining of the shell/core structure with an average diameter of approximately 0.6 µm, and the TGA analyses demonstrated the thermal protection of LAE by the shell of the fibers. Released LAE reached the equilibrium state in ETOH 95% during the first 3 hours, maintaining a higher concentration than the MIC value obtained in L. innnocua (10 ppm). The results demonstrate that new packaging materials with antimicrobial activity such as PLA/PVOH-LAE polymeric fibers with a shell/core structure can be obtained through the coaxial electrospinning technique. Keywords: coaxial electrospinning, ethyl lauroyl arginate, fibers, shell/core, food packaging. Resumen El electrohilado coaxial (EC) es una tecnología que permite encapsular compuestos activos como el etil lauroil arginato (LAE) en estructuras tipo pared/núcleo con la finalidad de desarrollar nuevos materiales antimicrobianos para el envasado de alimentos que ralenticen la liberación del compuesto y extiendan la vida útil del alimento. Por tal razón, el objetivo de este estudio consistió en desarrollar fibras antimicrobianas tipo pared/núcleo mediante EC. Dos polímeros con distinto carácter hidrofílico como el poli (ácido láctico) (PLA) para la pared y poli (alcohol vinílico) (PVOH) y LAE para el núcleo se utilizaron para obtener las fibras PLA/PVOH-LAE, y ralentizar la liberación del compuesto antimicrobiano. La morfología de las fibras se evaluó mediante microscopía óptica y sus propiedades térmicas mediante análisis termogravimétricos (TGA). Se realizaron estudios de liberación del LAE en un simulante de alimentos graso (ETOH 95%), y se comparó con la concentración mínima inhibitoria (MIC) hacia una bacteria Gram positiva Listeria innnocua. Las micrografías ópticas evidenciaron la obtención de la estructura pared/núcleo con un diámetro promedio de 0,6 µm aproximadamente, y el análisis TGA demostró la protección térmica del LAE por la pared de las fibras. El LAE liberado alcanzó el estado de equilibrio en ETOH 95% durante las 3 hr iniciales, manteniendo una concentración superior a la MIC obtenida para L. innnocua (10 ppm). Los resultados demuestran que nuevos materiales de envase con actividad antimicrobiana como fibras poliméricas PLA/PVOH-LAE con estructura pared/núcleo pueden ser obtenidos mediante la técnica de electrohilado coaxial. Palabras clave: electrohilado coaxial, etil lauroil arginato, fibras, pared/núcleo, envase de alimentos

    Beta-Cyclodextrin: Eugenol Inclusion Complexes: Characterization and Antifungal Capacity

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    Eugenol (EUG) is the principal component of clove essential oil. It has demonstrated excellent antifungal properties against B. cinerea, one of the most important fungus in the fresh fruit decay. However, this substance is highly volatile, thermolabile and the direct contact with a food induce undesirable changes in the organoleptic properties. For this reason, the application of EUG represents a big challenger and its encapsulation through inclusion complexes formation with β-cyclodextrin (β-CD) is presented as a solution. In this way, the aim of this work was to develop, characterize and assess the antifungal capacity of inclusion complexes β-CD:EUG. For this, co-precipitation was used as method of inclusion complexes synthesis. The quantity of entrapped EUG was determined by gaseous chromatography. The inclusion complexes were characterized by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR). Moreover, the antifungal activity was probed in a headspace system. Results showed that the EUG entrapped quantity was of 68,5 mg/g inclusion complexes. Furthermore, the characteristic peaks of EUG did not appear in inclusion complexes TGA thermogram and FTIR spectrum which confirm the effective compound encapsulation. Finally, inclusion complexes inhibited the growing of A. cinerea at 53% and avoided the fungal sporulation. These findings suggest that the β- CD:EUG inclusion complexes are suitable to use in the storage and transportation of fresh fruits to prevent their deterioration. Keywords: Botrytis cinerea, fresh fruits, headspace. Resumen El eugenol (EUG) es el principal componente del aceite esencial de clavo de olor. Éste ha destacado por su efectivo control de Botrytis cinerea, uno de los hongos más importantes que provoca la pudrición de frutas frescas. Sin embargo, esta sustancia es altamente volátil, termolábil y provoca cambios desagradables en las propiedades organolépticas del alimento si está en contacto directo con el mismo, por lo que su aplicación presenta un gran desafío. Ante esto, se propone su encapsulación a través de la formación de complejos de inclusión con β-ciclodextrina (β-CD). En este sentido, el objetivo de la presente investigación fue desarrollar, caracterizar y evaluar la capacidad antifúngica de complejos de inclusión β-CD:EUG. Éstos se sintetizaron mediante el método de co-precipitación, y la cantidad de EUG atrapada en la β-CD fue cuantificada por cromatografía de gases. Los complejos de inclusión se caracterizaron a través de análisis termogravimétrico (TGA) y espectroscospía infrarroja con transformada de Fourier (FTIR). Además, su actividad antifúngica se evaluó en un sistema de espacio de cabeza. Los resultados mostraron que la cantidad de EUG atrapada fue de 68,5 mg/g de complejo de inclusión. Además, en su termograma TGA y espectro FTIR no se observaron los picos característicos del EUG, confirmando la efectiva encapsulación del compuesto. Finalmente, los complejos de inclusión inhibieron el 53% del crecimiento de B. cinerea y evitaron su esporulación. Estos resultados permiten sugerir el uso de complejos de inclusión β-CD:EUG en el almacenamiento y transporte de frutas frescas para prevenir su deterioro. Palabras clave: Botrytis cinerea, frutas frescas, espacio de cabeza

    Development of poly(lactic acid) films with propolis as a source of active compounds: biodegradability, physical, and functional properties

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    Active films (AFs) using poly(lactic acid) (PLA) as a polymeric matrix containing various propolis concentrations (5, 8.5, and 13%) as the active agent (AA) were developed using a casting method. The purpose was to determine the effects of the incorporation of AA on the physical properties of the films and to evaluate the antioxidant and antimicrobial activities. Tensile strength and elastic modulus of the AFs decreased relative to the control (PLA without AA). Introducing the active substances from propolis into the PLA also affected its thermal properties (glass transition). Adding AAs to the polymer generated more opacity with a green-yellowish color compared to the control. In addition, AFs exhibited reduced water vapor permeability as the AA concentration increased. Biodegradation assay showed that the AFs degraded faster than the control. AFs exhibited antioxidant activity, which was measured as the ability to scavenge free radicals (2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate)), due to the presence of bioactive compounds (phenolics). Antimicrobial activity was evaluated against Escherichia coli and showed a reduction over 4-log cycles. Therefore, incorporation of propolis is a useful strategy for the development of active packaging with antioxidant and antimicrobial effects, which increase the shelf life of food products. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47090.Direccion de Investigacion of Pontificia Universidad Catolica de Valparaiso [DI-037-362-14]University of Santiago de Chile [1555-Vridei O81771GL_CONT

    Acute renal failure after influenza vaccination: a case report

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    A fifty-three years old surgeon had acute renal failure consisting with acute tubulo-interstizial nephropaty twelve days after influenza vaccination; he was on statin therapy since one month. He was given steroidal therapy and fully recovered two weeks apart. This is the fourth case report of acute renal failure after influenza vaccination in patients on statins therapy. The case we describe could account for a underestimated, even if very rare, phenomenon

    Deficiency and Also Transgenic Overexpression of Timp-3 Both Lead to Compromised Bone Mass and Architecture In Vivo

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    Tissue inhibitor of metalloproteinases-3 (TIMP-3) regulates extracellular matrix via its inhibition of matrix metalloproteinases and membrane-bound sheddases. Timp-3 is expressed at multiple sites of extensive tissue remodelling. This extends to bone where its role, however, remains largely unresolved. In this study, we have used Micro-CT to assess bone mass and architecture, histological and histochemical evaluation to characterise the skeletal phenotype of Timp-3 KO mice and have complemented this by also examining similar indices in mice harbouring a Timp-3 transgene driven via a Col-2a-driven promoter to specifically target overexpression to chondrocytes. Our data show that Timp-3 deficiency compromises tibial bone mass and structure in both cortical and trabecular compartments, with corresponding increases in osteoclasts. Transgenic overexpression also generates defects in tibial structure predominantly in the cortical bone along the entire shaft without significant increases in osteoclasts. These alterations in cortical mass significantly compromise predicted tibial load-bearing resistance to torsion in both genotypes. Neither Timp-3 KO nor transgenic mouse growth plates are significantly affected. The impact of Timp-3 deficiency and of transgenic overexpression extends to produce modification in craniofacial bones of both endochondral and intramembranous origins. These data indicate that the levels of Timp-3 are crucial in the attainment of functionally-appropriate bone mass and architecture and that this arises from chondrogenic and osteogenic lineages

    Bone Marrow Osteoblast Damage by Chemotherapeutic Agents

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    Hematopoietic reconstitution, following bone marrow or stem cell transplantation, requires a microenvironment niche capable of supporting both immature progenitors and stem cells with the capacity to differentiate and expand. Osteoblasts comprise one important component of this niche. We determined that treatment of human primary osteoblasts (HOB) with melphalan or VP-16 resulted in increased phospho-Smad2, consistent with increased TGF-β1 activity. This increase was coincident with reduced HOB capacity to support immature B lineage cell chemotaxis and adherence. The supportive deficit was not limited to committed progenitor cells, as human embryonic stem cells (hESC) or human CD34+ bone marrow cells co-cultured with HOB pre-exposed to melphalan, VP-16 or rTGF-β1 had profiles distinct from the same populations co-cultured with untreated HOB. Functional support deficits were downstream of changes in HOB gene expression profiles following chemotherapy exposure. Melphalan and VP-16 induced damage of HOB suggests vulnerability of this critical niche to therapeutic agents frequently utilized in pre-transplant regimens and suggests that dose escalated chemotherapy may contribute to post-transplantation hematopoietic deficits by damaging structural components of this supportive niche

    Railway bridge structural health monitoring and fault detection: state-of-the-art methods and future challenges

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    Railway importance in the transportation industry is increasing continuously, due to the growing demand of both passenger travel and transportation of goods. However, more than 35% of the 300,000 railway bridges across Europe are over 100-years old, and their reliability directly impacts the reliability of the railway network. This increased demand may lead to higher risk associated with their unexpected failures, resulting safety hazards to passengers and increased whole life cycle cost of the asset. Consequently, one of the most important aspects of evaluation of the reliability of the overall railway transport system is bridge structural health monitoring, which can monitor the health state of the bridge by allowing an early detection of failures. Therefore, a fast, safe and cost-effective recovery of the optimal health state of the bridge, where the levels of element degradation or failure are maintained efficiently, can be achieved. In this article, after an introduction to the desired features of structural health monitoring, a review of the most commonly adopted bridge fault detection methods is presented. Mainly, the analysis focuses on model-based finite element updating strategies, non-model-based (data-driven) fault detection methods, such as artificial neural network, and Bayesian belief network–based structural health monitoring methods. A comparative study, which aims to discuss and compare the performance of the reviewed types of structural health monitoring methods, is then presented by analysing a short-span steel structure of a railway bridge. Opportunities and future challenges of the fault detection methods of railway bridges are highlighted
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