Polyvinylamine membranes containing graphene-based nanofillers for carbon capture applications

In the present study, the separation performance of new self-standing polyvinylamine (PVAm) membranes loaded with few-layer graphene (G) and graphene oxide (GO) was evaluated, in view of their use in carbon capture applications. PVAm, provided by BASF as commercial product named Lupamin\u2122, was purified obtaining PVAm films with two degrees of purification: Low Grade (PVAm-LG) and High Grade (PVAm-HG). These two-grade purified PVAm were loaded with 3 wt% of graphene and graphene oxide to improve mechanical stability: indeed, pristine tested materials proved to be brittle when dry, while highly susceptible to swelling in humid conditions. Purification performances were assessed through FTIR-ATR spectroscopy, DSC and TGA analysis, which were carried out to characterize the pristine polymer and its nanocomposites. In addition, the membranes\u2032 fracture surfaces were observed through SEM analysis to evaluate the degree of dispersion. Water sorption and gas permeation tests were performed at 35 \ub0C at different relative humidity (RH), ranging from 50% to 95%. Overall, composite membranes showed improved mechanical stability at high humidity, and higher glass transition temperature (Tg) with respect to neat PVAm. Ideal CO2/N2 selectivity up to 80 was measured, paired with a CO2 permeability of 70 Barrer. The membranes\u2019 increased mechanical stability against swelling, even at high RH, without the need of any crosslinking, represents an interesting result in view of possible further development of new types of facilitated transport composite membranes

Ionically conducting and photoresponsive liquid crystalline terpolymers: Towards multifunctional polymer electrolytes

[EN] We have prepared a series of new ionically conducting polymer electrolytes consisting of side-chain liquid crystal terpolymers with mesogenic azobenzenes, sulfonic acid groups and methyl methacrylate. The poly[10-(4-methoxyazobenzene -4'-oxy)decyl methacrylate] -co-poly[2-acrylamido-2-methyl-1-propanesulfonic acid]-copoly [methyl methacrylate]s, 10-MeOAzB/AMPS/MMA terpolymers, were synthesised by a one-pot conventional radical polymerisation. All samples were characterised by NMR, GPC/SEC, FT-IR, POM, XRD, DSC, UV-visible spectrophotometry and EIS. The terpolymers have light responsive properties, and exhibit liquid crystallinity over a wide range of compositions. Above a certain threshold of AMPS content, the 10-MeOAzB/AMPS/MMA terpolymers exhibit ionic conductivities in the 10(-8)-10(-4)S.cm(-1) range, with signs of decoupling of ionic mobility from segmental motions of the polymer.ARG and AMF thank the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs, and the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03 and UPOVCE-3E-013 and the awarding of two FPI and FPU pre-doctoral grants. AMF and NFKA would like to thank the Royal Academy of Engineering for the award of the Newton Research Collaboration Programme grant NRCP1516/4/61. AMF acknowledges the School of Engineering of the University of Aberdeen for financial support.Vanti, L.; Alauddin, SM.; Zaton, D.; Aripin, N.; Giaccinti-Baschetti, M.; Imrie, C.; Ribes-Greus, A.... (2018). Ionically conducting and photoresponsive liquid crystalline terpolymers: Towards multifunctional polymer electrolytes. European Polymer Journal. 109:124-132. https://doi.org/10.1016/j.eurpolymj.2018.08.033S12413210

Hydrothermal Alteration of Ultramafic Rocks in Ladon Basin, Mars - Insights From CaSSIS, HiRISE, CRISM, and CTX

The evolution of the Ladon basin has been marked by intense geological activity and the discharge of huge volumes of water from the Martian highlands to the lowlands in the late Noachian and Hesperian. We explore the potential of the ExoMars Trace Gas Orbiter/Color and Stereo Surface Imaging System color image data set for geological interpretation and show that it is particularly effective for geologic mapping in combination with other data sets such as HiRISE, Context, and Compact Reconnaissance Imaging Spectrometer for Mars. The study area displays dark lobate flows of upper Hesperian to early Amazonian age, which were likely extruded from a regional extensional fault network. Spectral analysis suggests that these flows and the underlying rocks are ultramafic. Two distinct altered levels are observed below the lobate flows. The upper, yellow-orange level shows hundreds of structurally controlled narrow ridges reminiscent of ridges of listwanite, a suite of silicified, fracture-controlled silica-carbonate rocks derived from an ultramafic source and from serpentine. In addition to serpentinite, the detected mineral assemblages may include chlorite, carbonates, and talc. Kaolin minerals are detected in the lower, white level, which could have formed by groundwater alteration of plagioclase in the volcanic pile. Volcanism, tectonics, hydrothermal activity, and kaolinization are interpreted to be coeval, with hydrothermal activity and kaolinization controlled by the interactions between the aquifer and the hot, ultramafic lobate flows. Following our interpretations, East Ladon may host the first listwanite ridges described on Mars, involving a hydrothermal system rooted in a Hesperian aquifer and affecting ultramafic rocks from a magmatic source yet to be identified

Rapid increases in obesity in Jamaica, compared to Nigeria and the United States

<p>Abstract</p> <p>Background</p> <p>Weight gain in adulthood is now common in many populations, ranging from modest gains in developing countries to a substantial percentage of body weight in some Western societies. To examine the rate of change across the spectrum of low to high-income countries we compared rates of weight change in samples drawn from three countries, Nigeria, Jamaica and the United States.</p> <p>Methods</p> <p>Population samples from Nigeria (n = 1,242), Jamaica (n = 1,409), and the US (n = 809) were selected during the period 1995–1999 in adults over the age of 19; participation rates in the original survey were 96%, 60%, and 60%, respectively. Weight in (kg) was measured on 3 different occasions, ending in 2005. Multi-level regression models were used to estimate weight change over time and pattern-mixture models were applied to assess the potential effect of missing data on estimates of the model parameters.</p> <p>Results</p> <p>The unadjusted weight gain rate (standard error) was 0.34(0.06), 1.26(0.12), 0.34(0.19) kg/year among men and 0.43(0.06), 1.28(0.10), 0.40(0.15) kg/year among women in Nigeria, Jamaica, US, respectively. Regression-adjusted weight change rates were significantly different across country, sex, and baseline BMI. Adjusted weight gain in Nigeria, Jamaica and US was 0.31(0.05), 1.37(.04), and 0.52(0.05) kg/year respectively. Women in Nigeria and the US had higher weight gains than men, with the converse observed among Jamaicans. The obese experienced weight loss across all three samples, whereas the normal weight (BMI < 25) had significant weight gains. Missing data patterns had an effect on the rates of weight change.</p> <p>Conclusion</p> <p>Weight change in sample cohorts from a middle-income country was greater than in cohorts from either of the low- or high-income countries. The steep trajectory of weight gain in Jamaica, relative to Nigeria and the US, is most likely attributable to the accelerating effects of the cultural and behavioral shifts which have come to bear on transitional societies.</p

EVALUATION OF THERMODYNAMIC INTERACTIONS OF SOLVENTS WITH STYRENE-DIENE BLOCK COPOLYMERS BY INVERSE GAS CHROMATOGRAPHIC MEASUREMENTS

Abstract-In this study, IGC technique was applied for the determination of some thermodynamic interaction parameters of different phase separated styrene blockcopolymer, namely poly(styrene-block-butadieneblock-styrene) [SBS], poly(styrene-block-isopreneblock-styrene) [SIS] and poly(styrene-block-ethylene butylene-block-styrene) [SEBS] with some aliphatic, alicyclic and aromatic hydrocarbons. In particular weight fraction activity coefficient, Flory\u2013Huggins interaction parameter and solubility parameter for both hydrocarbons and polymers were obtained

Self-consistent cross-field transport model for core and edge plasma transport

International audienceA two-equation model to self-consistently determine cross-field fluxes in the edge and scrape-off layer region of diverted plasma is used to complete 2D mean-field edge transport description of plasma wall interaction. Inspired by the Reynolds Average Navier-Stokes simulations for neutral fluids, this model is based on the local evolution of the turbulent kinetic energy κ and its dissipation rate ε. These two equations are algebraically derived for RANS modeling and are very slightly modified and adapted to describe self-consistent plasma turbulent transport. The general features of the model are discussed and bridged to the well-known predatorprey and quasilinear models commonly used to investigate plasma transport. Specific closures are proposed based on the interchange turbulence. Results of the 1D model are confronted to experimental evidence by analyzing the computed SOL width and comparing the results to the existing scaling law for L-mode plasmas. Introducing a dependence on the shear of large scale flows, typically the zonal flows, 1D simulations can exhibit an H-mode like transition when increasing the input power, generating an increased stored energy thanks to an interface barrier located at the separatrix. Further 2D plasma-wall interaction simulations for WEST are analyzed that show a good match with the experimental profiles, as well as a ballooned transport driving turbulent transport in the divertor SOL and nearly no transport in the private flux region. The SOL width of WEST is also recovered. These results show the remarkable capability of the κ-ε model to capture key aspects of the physics of turbulent transport throughout the plasma knowing that a unique scalar free parameter is available to tune cross field transport in the whole 2D cross section of the plasma

Relating mass transport properties to viscoelastic response in micro-phase separated Styrene block copolymers

The correlation between linear viscoelasticity and mass transport properties in styrene block copolymers has been investigated and discussed in terms of segmental dynamics of the soft block. The samples were phase separated polystyrene-block-polybutadiene-block-polystyrene [SBS], polystyrene-block-polyisoprene-block-polystyrene [SIS] and polystyrene-block-poly(ethylene butylene)-block-polystyrene [SEBS]. All samples have a styrene content of approximately 30%. Linear viscoelastic characterization was carried out performing small angle oscillatory shear experiments in a wide range of temperatures between the soft block Tg and room temperature. The latter experimental data were analyzed by Time-Temperature Superposition. The relaxation spectrum has been determined and the monomeric friction factor has been extracted. This value has been correlated with results from diffusion of a small foreign molecule (cyclohexane) in the block copolymers. Solubility and diffusivity of cyclohexane in films samples of the investigated copolymers as function of concentration at 60ºC have been measured by means of sequences of differential vapour sorption experiments run in a pressure decay apparatus. The effects of both molecular architecture (linear and star-branched for SBS) and microstructure of the elastomer mid-segment (polybutadiene vs poly(ethylene butylene) and polyisoprene) were considered. Solubility results were interpreted in terms of contributions from rubbery and glassy phases and pertinent results were used to derive the mobility coefficient from measured data of fickian diffusivity. Comparison between mobility coefficients in the binary system as function of solute concentration revealed that friction factor for solute molecules in SEBS and SIS is significantly higher than in SBS

Diffusione di cicloesano in copolimeri a blocchi a base stirenica: relazioni tra il trasporto di massa e le propriet\ue0 viscoelastiche dei materiali

Il processo di assorbimento e diffusione del cicloesano in diversi copolimeri a blocchi a base stirenica \ue8 stato studiato e correlate alle propriet\ue0 viscoelastiche degli stessi. La solubilit\ue0 e diffusivit\ue0 di tale penetrante in poli(stirene-b-butadiene-b-stirene [SBS], poli(stirene-b-isoprene-b-stirene [SIS] e poli(stirene-b-etilenebutilene-b-stirene) [SEBS] sono state misurate sperimentalmente alla temperatura di 60\ub0C tramite prove di assorbimento differenziale condotte in un sistema a decadimento di pressione. I risultati hanno mostrato una sostanziale omogeneit\ue0 di comportamento per ci\uf2 che concerne l\u2019assorbimento di cicloesano mentre l\u2019SBS \ue8 risultato in generale dotato di una maggiore diffusivit\ue0 rispetto a SIS e SEBS. La peculiarit\ue0 strutturale di tali polimeri, che si presentano come sistemi eterogenei ove domini stirenici ( vetro) e dienici (gomma) risultano segregati a livello nanometrico, ha permesso di rielaborare i dati ottenuti in termini dei contributi dei diversi domini e di risalire ai parametri cinetici che regolano il processo diffusivo. In particolare il confronto tra i diversi dati di solubilit\ue0 e diffusivit\ue0 ha permesso di analizzare il comportamento della mobilit\ue0 del penetrante all\u2019interno dei diversi polimeri, che in linea con quanto visto per il coefficiente di diffusione \ue8 risultato significativamente pi\uf9 alta per SBS rispetto agli altri copolimeri considerati. Una tale andamento \ue8 stato confermato anche dalle prove reologiche a cui sono stati sottoposti i materiali, condotte in un ampio intervallo di temperature compreso tra la Tg dei segmenti dienici e la temperatura ambiente. Tale analisi condotta tramite scansioni di frequenza in regime di viscoelasticit\ue0 lineare small angle oscillatory shear experiments ha permesso di ottenere l\u2019andamento dei moduli dei diversi materiali in funzione della frequenza e l\u2019ottenimento delle relative \u201cmaster curve\u201d tramite la tecnica di sovrapposizione tempo-temperatura. L\u2019analisi dello spettro di rilassamento ha permesso poi di stimare il fattore di frizione monomerico che \ue8 stato infine correlato con i dati di mobilit\ue0 ottenendo un sostanziale accordo

Diffusion of cyclohexane in styrene block copolymers, relationship between mass transport and viscoelastic properties

The mass transport properties of cyclohexane in different phase separated styrene blockcopolymer, namely polystyrene-block-polybutadiene-block-polystyrene [SBS], polystyrene-blockpolyisoprene- block-polystyrene [SIS] and polystyrene-block-poly(ethylene butylene)-blockpolystyrene [SEBS] were investigated. The solubility and diffusivity in films samples have been measured, as function of concentration, at 60\ubaC by means of sequences of differential vapor sorption experiments run in a pressure decay apparatus. The effects of both molecular architecture (linear and star-branched for SBS) and microstructure of the elastomer mid-segment (polybutadiene vs poly(ethylene butylene) and polyisoprene) were considered. The sorption results were interpreted and modeled in terms of contributions from rubbery and glassy phases. Comparison between the different data in the binary system as function of solute concentration revealed that friction factor for solute molecules in SEBS and SIS is significantly higher than in SBS. Such results were also confirmed by linear viscoelastic characterization of the different polymers that has been carried out performing small angle oscillatory shear experiments in a wide range of temperatures between the soft block Tg and room temperature. The latter experimental data were analyzed by Time-Temperature Superposition. The relaxation spectrum has been determined and the monomeric friction factor has been extracted. This value has been correlated with results from diffusion experiments leading to a substantial agreement

A κ − ε model for plasma anomalous transport in tokamaks: closure via the scaling of the global confinement

International audienceA reduced model for radial anomalous transport of plasma in tokamaks, inspired by the Reynolds-Averaged Navier-Stokes (RANS) approach, is presented assuming diffusion as governing mechanism. In order to self-consistently calculate transport coefficients, an empirical equation is built for the turbulent kinetic energy and the system is closed via the scaling law of global confinement. In such way the SOL width appears to recover experimental dependencies with respect to machine parameters and interestingly, when the model is implemented in a 2D transport code for a realistic study-case, mean fields retrieve some features already observed in 1st-principle turbulent codes