Aplicaciones eléctricas del acrilonitrilo butadieno estireno (ABS) reforzado con neumáticos fuera de uso (GTR)

La masiva fabricación de neumáticos, así como su posterior almacenamiento una vez utilizados, constituye un grave problema medioambiental al que se intenta dar salida de diversas formas, entre las que se encuentra el mezclar estos neumáticos fuera de uso (old used tires, GTR) con diferentes polímeros termoplásticos y termoestables. Estas mezclas se realizan variando el tratamiento previo al que se somete el GTR, el grado de desvulcanizado, las condiciones de mezcla o prensado, etc. Posteriormente, se analizan estas mezclas estructural y mecanicamente, buscando posibles aplicaciones industriales para ellas. El presente trabajo, pretende conseguir materiales aptos para la industria eléctrica a partir de la mezcal del Acrilonitrilo butadieno estireno (ABS) reutilizado con neumáticos fuera de uso (GTR), pero partiendo del requisito de unos mínimos costes de reciclado posibles, es decir, utilizando GTR vulcanizado y sin aplicar ningún pretratamiento previo, y en cambio, actuando sobre el tamaño de sus partículas, el cual se puede conseguir con un simple y economico tamizado. Otra novedad que introduce el presente estudio, es el elevado número de compuestos analizados, aparte del profundo analisis a los que se les ha sometido (dieléctrico, mecánico, térmico y de microestructura), obteniendose de cada ensayo una gran cantidad de variables. Los compuestos se obtuvieron tomando como variables los tres tamaños de particula del GTR (p<200μm, 200<p<500μm, y p>500μm), y las siete concentraciones de GTR en la mezcla (0%, 5%, 10%, 20%, 40%, 50% y70%), lo que representa, un total de 21 nuevos compuestos. Aparte, para que los ensayos dieléctricos fueran lo más exhaustivos posibles y mostraran el comportamiento del compuesto en condiciones muy diversas, se consideró un amplio régimen de temperaturas (30ºC hasta 120ºC) así como de frecuencias (1・10  -2 Hz hasta 3・106 Hz). Todos estos datos, han permitido caracterizar con bastante exactitud las propiedades de los nuevos compuestos, y dependiendo de estos resultados, se han buscado posibles aplicaciones eléctricas, con el requisito de que estas debían ajustarse a las Normativas Oficiales

Unexpected differences between thermal and photoinitiated cationic curing of a diglycidyl ether of bisphenol A modified with a multiarm star poly(styrene)-b-poly(ε-caprolactone) polymer

The effect of adding a multiarm star poly(styrene)-b-poly(ε-caprolactone) polymer on the cationic thermal and photoinitiated curing of diglycidyl ether of bisphenol A was studied. This star-polymer decelerated the thermal curing of diglycidyl ether of bisphenol A and modified the final structure of the epoxy matrix. The photocuring was influenced significantly by the addition of the multiarm star. When the proportion of this modifier added was 5%, much more time was necessary for complete photocuring (160 min at 40ºC). In the presence of 10% of modifier, the degree of photocuring reached was very low (0.196 at 120°C). A subsequent thermal post-curing was necessary to cure completely the system. During photocuring in presence of poly(styrene)-b-poly(ε-caprolactone), the formation of dormant species, which are reactivated when the temperature increases, takes places. The kinetics of the thermal curing and the photocuring was analyzed using an isoconversional method due to the complexity of the reactive process. Applying this method, it has been confirmed the dependence of activation energy on the degree of conversion. The fracture morphology analyzed by scanning electron microscopy exhibited a second phase originated during photocuring by the presence of the modifier

Study of the thermal degradation of bioactive sol-gel coatings for the optimization of its curing process

A set of materials has been prepared by sol-gel process containing different quantities of hydroxyapatite (0, 2.5 and 5% HAp w/w) using as silica precursors glycidyloxypropyltrimethoxysilane (GPTMS) and triethoxyvinylsilane (VTES). In order to optimize the curing process to obtain sintherized systems (inorganic network) or hybrid systems (organic&-inorganic) a TG and FTIR studies have been developed and degradation kinetic triplet parameters were obtained (the activation energy, pre-exponential factor, and function of degree of conversion). The kinetic study was analyzed by means of an integral isoconversional non-isothermal procedure (model free), and the kinetic model was determined by the Coats&-Redfern method and through the compensation effect (IKR). All the systems followed the n = 6 kinetic model. The addition of HAp increases the thermal stability of the systems. The isothermal degradation was simulated from non-isothermal data, and the curing process could be defined to obtain the two types of materials. Temperature under 250 °C allows the formation of hybrids networks.Publicad

Características dieléctricas de diversos polímeros (PVC, EVA, HDPE, y PP) reforzados con neumáticos fuera de uso (GTR)

La masiva fabricación de neumáticos y la dificultad para su almacenamiento o eliminación constituye un grave problema medioambiental. En la actualidad, se utilizan diversos metodos para el reciclaje de los neumáticos, como por ejemplo la trituración mecánica, que separa el caucho vulcanizado del acero y las fibras, utilizandose este caucho en numerosas aplicaciones industriales como pavimentos, aislantes, calzados, etc. El presente artículo se centra en buscar una nueva aplicación para estos neumáaticos reutilizados (GTR), y para ello, se ha mezclado el polvo de los neumáticos con diferentes polímeros termoplásticos como son el Policloruro de Vinilo (PVC), el Polietileno de Alta Densidad (HDPE), el Etileno Acetato de Vinilo (EVA) y el Polipropileno (PP), comprobando hasta que valores de concentracion en GTR admitenestos nuevos compuestos manteniendo dentro de unos valores aceptables sus propiedades dielectricas, y por tanto, sus posibles aplicaciones industriales en la fabricación de aislantes para cables eléctricos. Concretamente, el polvo de los neumáticos reutilizados y con un tamaño de partícula inferior a 200 μm, ha sido mezclado con los polímeros con cuatro concentraciones diferentes, 5%, 10%, 20% y 50% en GTR para asi determinar su comportamiento mediante los ensayos dieléctricos realizados en un rango de temperaturas que varia desde los 30oC hasta los 120oC, y con unas frecuencias entre 1・10  -2 Hz, hasta 3・10  6Hz, analizandose la conductividad, la permitividad, el factor de perdidas dieléctricas, las relajaciones, etc. Finalmente, las superficies de fractura de las muestras compuestas han sido evaluadas por microscopía electronicade barrido (SEM)

Dual-curable stereolithography resins for superior thermomechanical properties

Stereolithography (SL) stands out as a relatively fast additive manufacturing method to produce thermoset components with high resolutions. The majority of SL resins consist of acrylate monomers which result in materials with cur-ing-induced shrinkage problems and this, in addition to the incomplete and non-uniform conversions reached in the SL process, results in poor mechanical properties. To address this issue, a dual-curing formulation was developed by mixing an epoxy monomer into a commercial multi-acrylate SL resin: the first curing stage is acrylate free-radical photopolymerization at ambient temperature, and the second curing stage is cationic epoxy homopolymerization at higher temperatures. The fully dual-cured materials are macroscopically homogeneous, with nanoscale domains observed by Atomic Force Mi-croscopy (AFM), and with unimodal tan delta peaks observed in Dynamic Mechanical Analysis (DMA). The uncured material was storage stable at ambient conditions for at least 9 weeks since the epoxy part was virtually unreactive at these temper-atures. With the dual-cured materials, a nearly 10-fold increase in Young’s modulus was achieved over the neat acrylate resin. At the thermal curing stage, the presence of diperoxyketal thermal radical initiator to the liquid formulation facilitated the polymerization of unreacted acrylates that remained from the SL process simultaneously with epoxy homopolymerization and helped the material attain improved properties

On Enriching the Levin-Wen model with Symmetry

Symmetry protected and symmetry enriched topological phases of matter are of great interest in condensed matter physics due to new materials such as topological insulators. The Levin-Wen model for spin/boson systems is an important rigorously solvable model for studying $2D$ topological phases. The input data for the Levin-Wen model is a unitary fusion category, but the same model also works for unitary multi-fusion categories. In this paper, we provide the details for this extension of the Levin-Wen model, and show that the extended Levin-Wen model is a natural playground for the theoretical study of symmetry protected and symmetry enriched topological phases of matter.Comment: 21 pages, 6 figure

Pathobiology and transmission of highly and low pathogenic avian influenza viruses in European quail (Coturnix c. coturnix)

European quail (Coturnix c. coturnix) may share with Japanese quail (Coturnix c. japonica) its potential as an intermediate host and reservoir of avian influenza viruses (AIV). To elucidate this question, European quail were experimentally challenged with two highly pathogenic AIV (HPAIV) (H7N1/HP and H5N1/HP) and one low pathogenic AIV (LPAIV) (H7N2/LP). Contact animals were also used to assess the viral transmission among birds. Severe neurological signs and mortality rates of 67% (H7N1/HP) and 92% (H5N1/HP) were observed. Although histopathological findings were present in both HPAIV-infected groups, H5N1/HP-quail displayed a broader viral antigen distribution and extent of microscopic lesions. Neither clinical nor pathological involvement was observed in LPAIV-infected quail. Consistent long-term viral shedding and effective transmission to naive quail was demonstrated for the three studied AIV. Drinking water arose as a possible transmission route and feathers as a potential origin of HPAIV dissemination. The present study demonstrates that European quail may play a major role in AI epidemiology, highlighting the need to further understand its putative role as an intermediate host for avian/mammalian reassortant viruses

Persistence of low pathogenic avian influenza virus in artificial streams mimicking natural conditions of waterfowl habitats in the Mediterranean climate

Altres ajuts: acords transformatius de la UABInstituto Nacional de Investigación y Tecnologı́a Agraria y Alimentaria PID2020-114060RR-C33-INFLUOMAAvian influenza viruses (AIVs) can affect wildlife, poultry, and humans, so a One Health perspective is needed to optimize mitigation strategies. Migratory waterfowl globally spread AIVs over long distances. Therefore, the study of AIV persistence in waterfowl staging and breeding areas is key to understanding their transmission dynamics and optimizing management strategies. Here, we used artificial streams mimicking natural conditions of waterfowl habitats in the Mediterranean climate (day/night cycles of photosynthetic active radiation and temperature, low water velocity, and similar microbiome to lowland rivers and stagnant water bodies) and then manipulated temperature and sediment presence (i.e., 10-13 °C vs. 16-18 °C, and presence vs. absence of sediments). An H1N1 low pathogenic AIV (LPAIV) strain was spiked in the streams, and water and sediment samples were collected at different time points until 14 days post-spike to quantify viral RNA and detect infectious particles. Viral RNA was detected until the end of the experiment in both water and sediment samples. In water samples, we observed a significant combined effect of temperature and sediments in viral decay, with higher viral genome loads in colder streams without sediments. In sediment samples, we didn't observe any significant effect of temperature. In contrast to prior laboratory-controlled studies that detect longer persistence times, infectious H1N1 LPAIV was isolated in water samples till 2 days post-spike, and none beyond. Infectious H1N1 LPAIV wasn't isolated from any sediment sample. Our results suggest that slow flowing freshwater surface waters may provide conditions facilitating bird-to-bird transmission for a short period when water temperature are between 10 and 18 °C, though persistence for extended periods (e.g., weeks or months) may be less likely. We hypothesize that experiments simulating real environments, like the one described here, provide a more realistic approach for assessing environmental persistence of AIVs

Mathematical and Statistical Techniques for Systems Medicine: The Wnt Signaling Pathway as a Case Study

The last decade has seen an explosion in models that describe phenomena in systems medicine. Such models are especially useful for studying signaling pathways, such as the Wnt pathway. In this chapter we use the Wnt pathway to showcase current mathematical and statistical techniques that enable modelers to gain insight into (models of) gene regulation, and generate testable predictions. We introduce a range of modeling frameworks, but focus on ordinary differential equation (ODE) models since they remain the most widely used approach in systems biology and medicine and continue to offer great potential. We present methods for the analysis of a single model, comprising applications of standard dynamical systems approaches such as nondimensionalization, steady state, asymptotic and sensitivity analysis, and more recent statistical and algebraic approaches to compare models with data. We present parameter estimation and model comparison techniques, focusing on Bayesian analysis and coplanarity via algebraic geometry. Our intention is that this (non exhaustive) review may serve as a useful starting point for the analysis of models in systems medicine.Comment: Submitted to 'Systems Medicine' as a book chapte