INCORPORATION OF NANOCLAY AND ORANGE PEELS EXTRACT INTO PLA FOR FOOD APPLICATIONS: MIGRATION ASSESSMENT

This research investigated the overall and specific migration from two different formulations of PLA: one obtained with addition of nanoclay as a filler (PLA_Clay), and another one obtained with the addition of an antioxidant extract from waste orange peels (OPE) as an active component for food application (PLA_OPE). Overall migration was always below the current European limit of 10 mg/dm2 set for food contact materials (maximum 0.2 mg/dm2 from PLA_Clay into distilled water and 2.7 mg/dm2 from PLA_OPE into 3 % acetic acid). Specific migration of clay elements and particles from PLA_Clay was evaluated by different techniques (atomic absorption spectroscopy, SEM and SEM microanalysis). A very limited release of clay elements was measured, with the highest migration found for calcium. SEM observation showed the release of particles also of size \u3c 1 µm. The migration testing conditions of 10 days at 40 °C showed a swelling of the PLA which was enhanced by nanoclay presence. A maximum 2.5 % of the phenolic compounds of the incorporated OPE were released in the simulant 20 % ethanol, which is compatible with the fact that the OPE had been obtained through aqueous ethanol extraction

Estudio histórico y epistemológico de la óptica como base para la enseñanza en 2º de Bachillerato

[ES] En este trabajo analizamos los textos originales de los grandes científicos sobre la naturaleza de la luz destacando los avances principales que aportaron, y proponemos una relación entre dichas ideas clave y los estándares de aprendizaje que han de ser adquiridas por nuestros alumnos. A partir de estas ideas clave y teniendo en cuenta los posibles obstáculos asociados, desarrollaremos el estudio de la óptica de manera constructiva, para que tanto los alumnos, como el profesor, aprovechen en mayor medida el proceso de enseñanza-aprendizaje.Álvarez Jubete, E.; Hevia Artime, I.; Toffolatti Ballarin, L. (2020). Estudio histórico y epistemológico de la óptica como base para la enseñanza en 2º de Bachillerato. Editorial Universitat Politècnica de València. 451-459. https://doi.org/10.4995/INN2019.2019.10026OCS45145

Construction of effective disposable biosensors for point of care testing of nitrite

© 2015. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/"In this paper we aim to demonstrate, as a proof-of-concept, the feasibility of the mass production of effective point of care tests for nitrite quantification in environmental, food and clinical samples. Following our previous work on the development of third generation electrochemical biosensors based on the ammonia forming nitrite reductase (ccNiR), herein we reduced the size of the electrodes’ system to a miniaturized format, solved the problem of oxygen interference and performed simple quantification assays in real samples. In particular, carbon paste screen printed electrodes (SPE) were coated with a ccNiR/carbon ink composite homogenized in organic solvents and cured at low temperatures. The biocompatibility of these chemical and thermal treatments was evaluated by cyclic voltammetry showing that the catalytic performance was higher with the combination acetone and a 40 °C curing temperature. The successful incorporation of the protein in the carbon ink/solvent composite, while remaining catalytically competent, attests for ccNiR’s robustness and suitability for application in screen printed based biosensors. Because the direct electrochemical reduction of molecular oxygen occurs when electroanalytical measurements are performed at the negative potentials required to activate ccNiR (ca. -0.4 V vs Ag/AgCl), an oxygen scavenging system based on the coupling of glucose oxidase and catalase activities was successfully used. This enabled the quantification of nitrite in different samples (milk, water, plasma and urine) in a straightforward way and with small error (1 – 6%). The sensitivity of the biosensor towards nitrite reduction under optimized conditions was 0.55 A M-1 cm-2 with a linear response range 0.7 – 370 μM.

Factors affecting the durability of water-based paint films

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Highly Sensitive Detection of Organophosphate Insecticides Using Biosensors Based on Genetically Engineered Acetylcholinesterase and Poly(3,4-Ethylenedioxythiophene)

A poly(3,4-ethylenedioxythiophene) (PEDOT) conducting ink is presented as a new electroactive material to be incorporated in acetylcholinesterase-(AChE-) based screen printed biosensors, acting not only as a conducting template but also as an electrochemical mediator for thiocholine oxidation. Two different strategies have been studied for the chemical synthesis of PEDOT: (a) a classical oxidative polymerisation and (b) a more innovative enzymatic polymerisation, giving a water-soluble PEDOT. The use of this water-soluble conducting polymer as mediator in screen-printed biosensors enables its deposition by printing like the rest of the layers. Highly sensitive acetylcholinesterase-(AChE-) based screen-printed biosensors have been constructed using both classical and enzymatic PEDOT, in combination with genetically modified AChE. These electrodes allow the measurement of thiocholine oxidation at potentials of 100 mV versus Ag/AgCl reference electrode through the mediation of PEDOT. Inhibition of thiocholine production in presence of CPO allow for detection of this pesticide in concentrations as low as 1·10−10 M

A quasi-reagentless point-of-care test for nitrite and unaffected by oxygen and cyanide

This work was supported by the Applied Molecular Biosciences Unit-UCIBIO which is financed by national funds from FCT/MCTES (UID/Multi/04378/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728). C.M.S. and T.M. thank the financial support from Fundacao para a Ciencia e Tecnologia (Fellowships SFRH/BPD/79566/2011 and PD/BD/109687/2015).The ubiquitous nitrite is a major analyte in the management of human health and environmental risks. The current analytical methods are complex techniques that do not fulfil the need for simple, robust and low-cost tools for on-site monitoring. Electrochemical reductase-based biosensors are presented as a powerful alternative, due to their good analytical performance and miniaturization potential. However, their real-world application is limited by the need of anoxic working conditions, and the standard oxygen removal strategies are incompatible with point-of-care measurements. Instead, a bienzymatic oxygen scavenger system comprising glucose oxidase and catalase can be used to promote anoxic conditions in aired environments. Herein, carbon screen-printed electrodes were modified with cytochrome c nitrite reductase together with glucose oxidase and catalase, so that nitrite cathodic detection could be performed by cyclic voltammetry under ambient air. The resulting biosensor displayed good linear response to the analyte (2–200 µM, sensitivity of 326 ± 5 mA M −1 cm −2 at −0.8 V; 0.8–150 µM, sensitivity of 511 ± 11 mA M −1 cm −2 at −0.5 V), while being free from oxygen interference and stable up to 1 month. Furthermore, the biosensor’s catalytic response was unaffected by the presence of cyanide, a well-known inhibitor of heme-enzymes.publishersversionpublishe

Paving the way for a wider use of composites in railway industry

Different types of phosphorus containing halogen-free flame retardants (FRs) were added to an epoxy-dicyandiamide resin formulation in order to study to which extent they affect its glass transition temperature (Tg), tensile properties, termal stability and burning behavior of the resin. For this purpose, an additive-type FR (ammonium polyphosphate encapsulated in melamine resin, MAPP) and two reactive-type FRs i) a commercial epoxy resin pre-reacted with 9,10-dihydro-oxa-10- phosphaphenanthrene-10-oxide, (DOPO), and ii) a phosphorus containing hardener (poly(m-phenylene methylphosphonate), (PMP) were used. It was observed that the addition of additive-type FR did not affect in great extent the Tg and provided a V-0 rating in UL94 test at low loadings. The addition of reactive-type FRs (DOPO and/or PMP), however, modified the structure of the chain network resulting in lower crosslink density as a consequence of their higher equivalent mass, but achieving also with low PMP content V-0 rating.This project has received funding from the Shift2Rail Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 777595