Modelling and parameter estimation of diethyl phthalate partitioning behaviour on glass and aluminum surfaces

The knowledge of the partitioning behaviour of semi-volatile organic compounds (SVOCs), such as phthalates, between different materials and their surrounding air is of extreme importance for quantifying levels of human exposure to these compounds, which have been associated with adverse health effects. Phthalates’ partitioning behaviour also represents a key property for modelling and assessing polymer degradation mechanisms associated with plasticiser loss. However, the characterisation of phthalates partitioning behaviour has been reported only for a limited number of compounds, mainly involving di-2-ethylhexyl phthalate (DEHP), di-isononyl phthalate (DINP) and di-isodecyl phtahalate (DIDP), while the characterisation of diethyl phthalate (DEP) partitioning has been overlooked. As one of the first plasticisers employed in the production of semi-synthetic plastics produced industrially in the late 19th and early 20th century, DEP plays an important role for understanding stability issues associated with historically significant artefacts in museum collections and archives. Here we show that the partitioning behaviour of DEP between borosilicate glass and aluminum surfaces and their surrounding air can be described by an exponential function of temperature, presenting a model to describe this relationship for the first time. Model parameters are estimated using nonlinear regression from experimental measurements acquired using 109 samples which have been equilibrated at different temperatures between 20 and 80 °C in sealed environments. Measured partition coefficients have been predicted accurately by our proposed model. The knowledge of DEP equilibrium distribution between adsorptive surfaces and neighbouring environments will be relevant for developing improved mathematical descriptions of degradation mechanisms related to plasticiser loss

Profiling Metacognition in Binge Eating Disorder

© 2020, The Author(s). Research has shown that metacognition may play a role in problem eating. In this study we explored whether aspects of metacognition are relevant to the understanding of binge eating in patients with Binge Eating Disorder. We aimed to ascertain: (1) the presence of metacognitive beliefs about binge eating; (2) the goal of, and stop signal for, binge eating; and (3) the impact of binge eating on self-consciousness. Ten Binge Eating Disorder patients took part in the study and were assessed using the metacognitive profiling semi-structured interview. Results suggested that all patients endorsed both positive and negative metacognitive beliefs about binge eating. The goals of binge eating were stop thinking about personal concerns and improve emotional state. All patients reported that they did not know when these goals had been reached. The stop signals for binge eating included physical discomfort, beliefs about binge eating not being the best way to solve problems, and environmental stimuli. All patients also confirmed that a reduction in self-consciousness occurred during a binge eating episode. The results of this study confirm that metacognition may indeed be relevant to the understanding of Binge Eating Disorder

Dual-polarization nonlinear Fourier transform-based optical communication system

New services and applications are causing an exponential increase in Internet traffic. In a few years, the current fiber optic communication system infrastructure will not be able to meet this demand because fiber nonlinearity dramatically limits the information transmission rate. Eigenvalue communication could potentially overcome these limitations. It relies on a mathematical technique called “nonlinear Fourier transform (NFT)” to exploit the “hidden” linearity of the nonlinear Schrödinger equation as the master model for signal propagation in an optical fiber. We present here the theoretical tools describing the NFT for the Manakov system and report on experimental transmission results for dual polarization in fiber optic eigenvalue communications. A transmission of up to 373.5 km with a bit error rate less than the hard-decision forward error correction threshold has been achieved. Our results demonstrate that dual-polarization NFT can work in practice and enable an increased spectral efficiency in NFT-based communication systems, which are currently based on single polarization channels

Effects of genotype and environment on B-glucan and dietary fibre contents in whole grain of barley grown in Brazil

The aim of this study was to determine general quality characteristics of whole grain of advanced lines of barley grown in Brazil and to determine the effects of genotype and growing location on β-glucan and dietary fibre contents. Barley cultivars, designated BRS 225, BRS 195 and MN 743, crop year 2008 and 2009, with three replications in field trial coordinated by the EMBRAPA Trigo/Passo Fundo were used in this research. The barley samples were analyzed in relation to their Total Dietary Fibre (TDF) contents and fractions for moisture and protein (N × 6.25) by using AACC Methods (American Association of Cereal Chemists, 1990). The β-Glucan content was assessed using the McCleary Enzymic Method for barley (McCleary and Codd, 1991). The data was statistically evaluated by System for Analysis and Separation Averages in Agricultural Experiment (SASM-Agri - version 4) and differences between means were located using Scott-Knott’s test (p<0,05). There were significant differences among the barley genotypes and different locations and crop years in terms of β-glucan, total dietary fibre (TDF), soluble dietary fibre (SDF) and insoluble dietary fibre (IDF) content (p<0.05). Climatic factors can affect positively or negatively the content of total dietary fibre and β-glucan, impacting on the final quality of the barley grain. Substantial variation in the content of fibre components was observed for barley cultivars grown in different years on the same location. These results indicate that environmental and genetic factors are involved in the total β-glucan content and dietary fibre of barley

Oxidative Coupling of Methane for Ethylene Production: Reviewing Kinetic Modelling Approaches, Thermodynamics and Catalysts

Ethylene production via oxidative coupling of methane (OCM) represents an interesting route for natural gas upscaling, being the focus of intensive research worldwide. Here, OCM developments are analysed in terms of kinetic mechanisms and respective applications in chemical reactor models, discussing current challenges and directions for further developments. Furthermore, some thermodynamic aspects of the OCM reactions are also revised, providing achievable olefins yields in a wide range of operational reaction conditions. Finally, OCM catalysts are reviewed in terms of respective catalytic performances and thermal stability, providing an executive summary for future studies on OCM economic feasibility

Water sorption and diffusion in cellulose acetate: The effect of plasticisers

The conservation of cellulose acetate plastics in museum collections presents a significant challenge, due to the material's instability. Several studies have led to an understanding of the role of relative humidity (RH) and temperature in the decay process. It is well established that the first decay mechanism in cellulose acetate museum objects is the loss of plasticiser, and that the main decay mechanism of the polymer chain involves hydrolysis reactions. This leads to the loss of sidechain groups and the breakdown of the main polymer backbone. However, interactions between these decay mechanisms, specifically the way in which the loss of plasticiser can modify the interaction between cellulose acetate and water, has not yet been investigated. This research addresses the role of RH, studying the sorption and diffusion of water in cellulose acetate and how this interaction can be affected by plasticiser concentration using Dynamic Vapour Sorption (DVS)

Characterising plasticised cellulose acetate-based historic artefacts by NMR spectroscopy: a new approach for quantifying the degree of substitution and diethyl phthalate contents

As one of the first semi-synthetic plastics produced industrially, cellulose acetate (CA)-based artefacts represent valued items in museum collections and archives which, however, present stability issues. High temperature and relative humidity conditions have long been known to promote changes in CA properties, for instance, due to the deacetylation of CA polymer chains and the loss of plasticiser from the polymer matrix. However, there is a need for improved methods for the quantification of plasticiser loss and CA deacetylation. In this context, this contribution presents a new approach for enabling the investigation of plasticiser loss and deacetylation degradation processes in historic plasticised CA-based artefacts which is based on high-resolution proton nuclear magnetic resonance spectroscopy (1H NMR). The proposed methods allow for simple and fast quantification of diethyl phthalate contents and average degree of substitution (DS), while requiring no need for extractive separation between the plasticiser and the CA polymer matrix prior to analysis. Both methods are demonstrated by their application towards a series of reference samples, historic artefacts and artificially aged plasticised CA materials. Our analysis indicates that plasticiser content and DS can be accurately quantified by using high-resolution 1H NMR and both methods have been compared to analyses performed using infrared spectroscopy

Unveiling the importance of diffusion on the deterioration of cellulose acetate artefacts: The profile of plasticiser loss as assessed by infrared microscopy

Cellulose acetate (CA) artefacts are one of the most valued plastic items in museum collections and are known to present stability issues, with the loss of plasticiser being among the main degradation processes. This study investigates the concentration distribution of diethyl phthalate (DEP) plasticiser throughout the dimensions of CA using infrared microscopy for the first time. Artificial ageing experiments using reference and historic CA plasticised with DEP were performed to assess the change in the concentration profiles as a function of ageing time. Our analysis indicates that the plasticiser loss from CA artefacts is likely controlled by its diffusion, resulting in a concentration gradient in which lower plasticiser contents are observed at the external layers of the material