Modelling Sorption and Transport of Gases in Polymeric Membranes across Different Scales: A Review

Professor Giulio C. Sarti has provided outstanding contributions to the modelling of fluid sorption and transport in polymeric materials, with a special eye on industrial applications such as membrane separation, due to his Chemical Engineering background. He was the co-creator of innovative theories such as the Non-Equilibrium Theory for Glassy Polymers (NET-GP), a flexible tool to estimate the solubility of pure and mixed fluids in a wide range of polymers, and of the Standard Transport Model (STM) for estimating membrane permeability and selectivity. In this review, inspired by his rigorous and original approach to representing membrane fundamentals, we provide an overview of the most significant and up-to-date modeling tools available to estimate the main properties governing polymeric membranes in fluid separation, namely solubility and diffusivity. The paper is not meant to be comprehensive, but it focuses on those contributions that are most relevant or that show the potential to be relevant in the future. We do not restrict our view to the field of macroscopic modelling, which was the main playground of professor Sarti, but also devote our attention to Molecular and Multiscale Hierarchical Modeling. This work proposes a critical evaluation of the different approaches considered, along with their limitations and potentiality

Detection of Faint BLR Components in the Starburst/Seyfert Galaxy NGC 6221 and Measure of the Central BH Mass

In the last decade, using single epoch virial based techniques in the optical band, it has been possible to measure the central black hole mass on large AGN1 samples. However these measurements use the width of the broad line region as a proxy of the virial velocities and are therefore difficult to be carried out on those obscured (type 2) or low luminosity AGN where the nuclear component does not dominate in the optical. Here we present the optical and near infrared spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT. Previous observations of NGC 6221 in the X-ray band show an absorbed (N_H=8.5 +/- 0.4 x 10^21 cm^-2) spectrum typical of a type 2 AGN with luminosity log(L_14-195 keV) = 42.05 erg/s, while in the optical band its spectrum is typical of a reddened (A_V=3) starburst. Our deep X-shooter/VLT observations have allowed us to detect faint broad emission in the H_alpha, HeI and Pa_beta lines (FWHM ~1400-2300 km/s) confirming previous studies indicating that NGC 6221 is a reddened starburst galaxy which hosts an AGN. We use the measure of the broad components to provide a first estimate of its central black hole mass (M_BH = 10^(6.6 +/- 0.3) Msol, lambda_Edd=0.01-0.03), obtained using recently calibrated virial relations suitable for moderately obscured (N_H<10^24 cm^-2) AGN.Comment: 13 pages, 3 figures, 1 table. Published in Frontiers in Astronomy and Space Science

Thermodynamic and Molecular Simulation of Pure and Mixed Gas Sorption in Polymeric Membranes

The characterization of polymeric membranes for gas separation is often performed with pure-gas tests, which are poor predictors of the performance at multicomponent conditions. In this work, the Non-Equilibrium Lattice Fluid (NELF) model was applied to study mixed-gas sorption in traditional glassy polymers employed for CO2/CH4 separation, such as Cellulose Acetates, and innovative ones, such as polyimides (HAB-6FDA), Thermally Rearranged (TR) Polymers and Polymers of Intrinsic Microporosity (PIMs). The model results were validated against experimental data. Strong nonidealities are observed, due to competitive sorption and penetrant induced swelling, that radically modify the gas transport at multicomponent conditions compared to pure-gas cases. These effects were correctly predicted by the model, as well as temperature, pressure and concentration effects. The Dual Mode Sorption (DMS) model was tested for the same systems and a sensitivity analysis of its parameterization procedure revealed great uncertainty associated to its predictions of multicomponent sorption. A new measurement protocol was developed for the determination of sorption isotherms for gas mixtures with an arbitrary number of components. Mixed-gas sorption of binary C2H6/CO2 and C2H6/CH4 mixtures and of ternary C2H6/CO2/CH4 mixtures in PIM-1 was measured with this technique, finding strong competitive effects related to the presence of ethane. Predictions of the NELF model for binary and ternary sorption, performed using only pure-gas parameters as input, were in good agreement with the experimental data. Predictive Molecular Dynamics simulations were carried out to investigate the effect of CO2 up to high concentration on several properties of a polymeric material. A systematic evaluation of thermodynamic and structural properties, local dynamics, gas solubility and diffusivity yielded good agreement with the experimental data and meaningful trends with respect to temperature, gas concentration and polymer molecular weight were obtained, thus confirming the possibility to investigate the properties of materials at the molecular level with great accuracy

Modelling Sorption and Transport of Gases in Polymeric Membranes across Different Scales: A Review

Professor Giulio C. Sarti has provided outstanding contributions to the modelling of fluid sorption and transport in polymeric materials, with a special eye on industrial applications such as membrane separation, due to his Chemical Engineering background. He was the co-creator of innovative theories such as the Non-Equilibrium Theory for Glassy Polymers (NET-GP), a flexible tool to estimate the solubility of pure and mixed fluids in a wide range of polymers, and of the Standard Transport Model (STM) for estimating membrane permeability and selectivity. In this review, inspired by his rigorous and original approach to representing membrane fundamentals, we provide an overview of the most significant and up-to-date modeling tools available to estimate the main properties governing polymeric membranes in fluid separation, namely solubility and diffusivity. The paper is not meant to be comprehensive, but it focuses on those contributions that are most relevant or that show the potential to be relevant in the future. We do not restrict our view to the field of macroscopic modelling, which was the main playground of professor Sarti, but also devote our attention to Molecular and Multiscale Hierarchical Modeling. This work proposes a critical evaluation of the different approaches considered, along with their limitations and potentiality

Modelling of masonry arches strengthened at extrados with FRCM

Masonry arches are amongst the most fascinating structures of the World's historical and architectural heritage. Their vulnerability to earthquakes pointed out the necessity of their preservation. Fiber Reinforced Cementitious Mortar (FRCM) composites have been recently used as a more sustainable alternative to FRPs in the strengthening of masonry structures, since they can overcome the limits FRP show as strengthening systems: poor behavior to high temperature, delamination with significant loss of material at the bonded surface, lack of vapor permeability, impossibility of application on humid surfaces, incompatibility of resins with masonry, high cost and reduced reversibility of the installation. These aspects have a critical relevance in the case of historical structures, whose features have to be preserved, and motivate researches about the use of FRCM on masonry structures, from both experimental and analytical points of view. In this paper, the results of numerical analyses performed on arches unstrengthened and strengthened at the extrados with PBO-FRCM composites are presented, taking as reference the experimental tests published in [1] and [2]. The aim of this research is to further investigate the benefits that the use of FRCM composites have on the mechanical performance of masonry. The used model, implemented in the finite element code DIANA FEA, succeeded in reproducing the mechanical behavior of the considered arches in terms of collapse mechanism, load carrying capacity and ductility.- (undefined

A Simple Pattern of Movement Is Not Able to Inhibit Experimental Pain in FM Patients and Controls: An sLORETA Study

Motor cortex activation seems to induce an analgesic effect on pain that would be different between patients with fibromyalgia (FM) and control subjects. This study was conducted to analyze the changes of the laser-evoked potentials (LEPs) induced during a finger tapping task in the FM patients and the controls employing a multi-dipolar analysis according to Standardized low resolution brain electromagnetic tomography (sLORETA) method. The LEPs from 38 FM patients and 21 controls were analyzed. The LEPs were recorded while subjects performed a slow and a fast finger tapping task. We confirmed that the difference between N1, N2 and P2 wave amplitudes between conditions and groups was not significant. In control subjects, the fast finger tapping task induced a modification of cortical source activation in the main areas processing laser stimulation from the moving hand independently from the movement speed. In summary, a simple and repetitive movement is not able to induce consistent inhibition of experimental pain evoked by the moving and the not moving hand in each group. It could interfere with LEP sources within the limbic area at least in control subjects, without inhibit cortical responses or explain the different pattern of motor and pain interaction in FM patients.The study was supported by the Bari Aldo Moro University Research fund