Formation of poly(butylene terephthalate): Secondary reactions studied by model molecules

The secondary reactions occurring in the formation poly(butylene terephthalate), leading to thermal degradation (in the temperature range 210°–280°C) or giving rise to tetrahydrofuran (in the temperature range 160°–190°C) have been kinetically studied with the aid of model molecules: 1,4-butylene dibenzoate and 4-hydroxybutyl benzoate. Some kinetic parameters have been determined; the effect of temperature and of catalysts and stabilizers has been considered and a mechanism is proposed for the formation of tetrahydrofuran from hydroxyl end groups.     

An Innovative In Vitro Open-Angle Glaucoma Model (IVOM) Shows Changes Induced by Increased Ocular Pressure and Oxidative Stress

Primary Open-Angle Glaucoma (POAG) is a neurodegenerative disease, and its clinical outcomes lead to visual field constriction and blindness. POAG’s etiology is very complex and its pathogenesis is mainly explained through both mechanical and vascular theories. The trabecular meshwork (TM), the most sensitive tissue of the eye anterior segment to oxidative stress (OS), is the main tissue involved in early-stage POAG, characterized by an increase in pressure. Preclinical assessments of neuroprotective drugs on animal models have not always shown correspondence with human clinical studies. In addition, intra-ocular pressure management after a glaucoma diagnosis does not always prevent blindness. Recently, we have been developing an innovative in vitro 3Dadvanced human trabecular cell model on a millifluidicplatform as a tool to improve glaucoma studies. Herein, we analyze the effects of prolonged increased pressure alone and, in association with OS, on such in vitro platform. Moreover, we verify whethersuch damaged TM triggers apoptosis on neuron-like cells. The preliminary results show that TM cells are less sensitive to pressure elevation than OS, and OS-damaging effects were worsened by the pressure increase. The stressed TM releases harmful signals, which increase apoptosis stimuli on neuron-like cells, suggesting its pivotal role in the glaucoma cascade.     

Effects of the Diffusion Layer Characteristics on the Performance of Polymer Electrolyte Fuel Cell Electrodes

Several carbon blacks and graphite were investigated as candidates for diffusion layer preparation in polymer electrolyte fuel cell electrodes (PEFC). Single cell electrochemical characterizations under different working cell conditions were carried out on the electrodes by varying the kind of carbon in the diffusion layer. An improvement in cell performance was found by using Shawinigan Acetylene Black (SAB) as carbon, resulting in a measured power density of about 360 mW cm^–2 in H₂/air operation at 70°C and 1/1 bar. Pore size distribution and scanning electron microscopy analyses were carried out to help the understanding of the different behaviour of the investigated carbon diffusion layers.     

Nafion electro-spun reinforced membranes for polymer electrolyte fuel cell

The introduction of different reinforcement materials (yarns, fibrils, etc) into the membranes has been investigated with the aim of maintaining adequate membrane properties in terms of mechanical strength, good chemical stability, low swelling at critical temperatures and a stable electrochemical performance in PEFC. An innovative technique for the development of membranes is based on polymeric films containing polymeric nanofibres obtained through electrospinning. The electrospinning of Nafion blends with polyvinylpirrolidone (PVP) and polystyrene (PS) was investigated in this work. In particular, the morphology and diameter of electrospun fibres as a function of the electrospinning parameters and solution preparation have been studied and in both cases, a critical concentration of blend solution was found. Beaded fibres were obtained above such a concentration and, below it, only fibre mats were observed. Reinforced Nafion-based membranes were realised by using the obtained spun films. Preliminary proton conductivity and fuel cell results have shown the capability of operating in a fuel cell environment with a slightly higher performance than pure Nafion but having an improved stability at high temperatures.     

Confinement of a polymer chain: An entropic study by Monte Carlo method

The properties of macromolecules in presence of an interface could be considerably modified due to confinement effects. When phase separations are performed in nanoconfined domains, the concurrent presence of high‐energy interfaces and conformational entropy constraints of the macromolecules causes profound differences in polymer aggregation behavior. Here, thermodynamics of a polymer chain in solution, confined by a three‐dimensional cubic interface, is studied by means of Monte Carlo method, focusing on the chain conformational entropy penalty arising from the excluded volume effects. The presented method might become a general tool for a preliminary evaluation of the thermodynamic effects due to the confinement of a polymer system. Further, the interface effects on Thermally Induced Phase Separation (TIPS) of polymer solutions, confined by High‐Pressure Homogenization, are experimentally studied, regarding final morphologies. It is confirmed how peculiar polymer morphologies are obtained only when the TIPS develops under nanoconfinement degrees above a threshold one. © 2017 American Institute of Chemical Engineers AIChE J, 64: 416–426, 2018     

ICA based identification of dynamical systems generating synthetic and real world time series

Independent Component Analysis (ICA) is a recent and well known technique used to separate mixtures of signals. While in general the researchers put their attention on the type of signals and of mixing, we focus our attention on a quite general class of models which act as sources of the time series, the dynamical systems. In this paper we focus our attention on the general problem to understand the behaviour of ICA methods with respect to the time series deriving from a specific dynamical system, selecting large classes of them, and using ICA to make separation. This study gives some interesting results that are very useful both to highlight some properties related to dynamical systems and to clarify some general aspects of ICA, by using both synthetic and real data. From one hand we study the features of the linear (simple and coupled) and non-linear (single and coupled) dynamical systems, stochastic resonances, chaotic and real dynamical systems. We have to stress that we obtain information about the separation of these systems and substantially how from the entropy of the complete system we can obtain the entropies of the single dynamical systems (so that we also could obtain a more realistic analogic circuit). On the other hand these results show the high capability of the ICA method to recognize the dynamical systems independently from their complexity and in the case of stochastic series ICA perfectly recognizes the different dynamical systems also where the Fourier Transform is irresolute. We also note that in the case of real dynamical systems we showed that ICA permits to recognize the information connected to the sources and to associate to it a phenomenological dynamical system that reproduce it (i.e. Organ Pipe, Stromboli Volcano, Aerosol Index).     

Three performativities of innovation in public transport planning

The article scrutinizes planners’ stories of innovation in contemporary public transport planning in three Scandinavian contexts (Denmark, Sweden and Norway). This analysis is accomplished by adapting Judith Butler’s post-structural feminist critical theory on performativity to the planning context. This theoretical framework is used to illuminate how planning is dynamically renewed, revised and consolidated over time by the individual routine actions of planners. From this perspective, the research identifies a set of repetitive acts – as recognizing specific windows of opportunity, anticipate and respond to political signals and create arguments and means of communication and persuasion – that constitute the contemporary transformation of professional practice in relation to planning politics. This analytics of performativity reveals how professional planning practices engage with transformative capacities of reshaping, re-enacting and re-experiencing guidance for the future within a set of meanings and forms of legitimation. These findings are intended to contribute to present and future planning practice and education in Scandinavian countries and elsewhere.     

Environmental Source terms during a few Reference Accident Sequences (RAS) of NET/ITER plant

This paper outlines the multi-code methodological approach foreseen to estimate the environmental releases of the activated corrosion/erosion products involved in accidents scenarios of a fusion machine. The radioactive releases associated with some Reference Accident Sequences RAS for the Next European Torus NET have been calculated, based on the following items: Radioactive Inventory RI, Process Source Term PST, and Environmental Source Term EST evaluation. The assessment concerns the NET Basic Performance Phase. Various materials (such as AISI 316L, graphite, beryllium, and boron carbide for the PFC, and water as coolant) and operating conditions (normal running and conditioning) are considered. Different codes have been used and compared. The final environmental releases have been obtained by using RELAP5/Mod.3, FUMO, NAUA-Mod.5 M, and ANITA codes.