Alkaline Stable Anion Exchange Membranes Based on Cross-Linked Poly(Arylene Ether Sulfone) Bearing Dual Quaternary Piperidines for Enhanced Anion Conductivity at Low Water Uptake

Alkaline stable anion exchange membranes based on the cross-linked poly(arylene ether sulfone) grafted with dual quaternary piperidine (XPAES-DP) units were synthesized. The chemical structure of the synthesized PAES-DP was validated using 1H-NMR and FT-IR spectroscopy. The physicochemical, thermal, and mechanical properties of XPAES-DP membranes were compared with those of two linear PAES based membranes grafted with single piperidine (PAES-P) unit and conventional trimethyl amine (PAES-TM). XPAES-DP membrane showed the ionic conductivity of 0.021 S cm−1 at 40 °C which was much higher than that of PAES-P and PAES-TM because of the possession of more quaternary ammonium groups in the cross-linked structure. This cross-linked structure of the XPAES-DP membrane resulted in a higher tensile strength of 18.11 MPa than that of PAES-P, 17.09 MPa. In addition, as the XPAES-DP membrane shows consistency in the ionic conductivity even after 96 h in 3 M KOH solution with a minor change, its chemical stability was assured for the application of anion exchange membrane fuel cell. The single-cell assembled with XPAES-DP membrane displayed a power density of 109 mWcm−2 at 80 °C under 100% relative humidity.

Unifying the Ambivalent Mechanisms of Protein-Stabilising Osmolytes

The mechanism of protein stabilization by zwiterionic osmolytes has remained a long-standing puzzle. While the prevalent mechanistic hypothesis suggests an ‘osmo-phobic’ model in which osmolytes are assumed to stabilize proteins by preferentially excluding themselves from the protein surface, emerging evidences of preferential binding of popular osmolyte trimethyl amine N-oxide (TMAO) with hydrophobic macromolecules contradict this view. Here we address these contrasting perspectives by investigating the folding mechanism of a set of mini proteins in aqueous solutions of two different osmolytes glycine and TMAO, via free energy simulations. Our results demonstrate that, while both osmolytes are found to stabilize the folded conformation of the mini proteins, their mechanism of actions are mutually diverse: Specifically, glycine always depletes from the surface of all mini proteins, thereby conforming to the osmophobic model; but TMAO is found to display ambivalent signatures of protein-specific preferential binding and exclusion to/from the protein surface. At molecular level, the presence of an extended hydrophobic patch in protein topology is found to be recurrent motif in proteins leading to favorable binding with TMAO. Finally, an analysis based upon the preferential interaction theory and folding free energetics reveals that irrespective of preferential binding vs exclusion of osmolytes, it is the relative preferential depletion of osmolytes on transition from folded to unfolded conformation of proteins, which drives the overall conformational equilibrium towards the folded state in presence of osmolytes. Taken together, moving beyond the model system and hypothesis, this work brings out ambivalent mechanism of osmolytes on proteins and provides an unifying justification.

From Fishing Gear to Granulates and Recycled Steel – An Eco Innovation Project

Plastix A/S, a cleantech company located in Lemvig, Denmark, received in August 2014 funding for the project Retrawl2, which is a part of the EU initiative ECO-Innovation project. Retrawl2 is co-funded by the European Union with the CIP ECO-Innovation initiative of the Competitiveness and Innovation Framework Programme, CIP. The aim of the RETRAWL is to upscale an innovative recycling technology, which transforms used maritime waste into plastic and steel commodities. The plastics are mainly polyamides and polyethylene from nets and trawls, and the steel are mainly carbon steel from taifun wires as parts of the nets and trawls.The suppliers of the used maritime equipment are Danish and other European fishing harbours, where equipment are stored, because it can be a challenge for the fishermen to dispose it. Also ghost nets are collected and delivered for recycling. In order to recycle nets to commodity plastics considerations of the quality of the product has been taken. The nets are made of materials of a high quality, because the abrasion resistance, the tension strength and the chemical resistance need to be high for the use of them in trawl. The quality of the recycled plastics will be high, when they are gently treated under the cutting, separation, washing and extrusion processes. In the processes the gently handling of the polymers is in focus to keep the degree of polymerisation of the polymers, since the strength of the plastics depends on the chain length of the polymers. The quality and the identity of the recycled plastics are verified through infrared spectroscopi, FTIR, differential scanning calorimetry, DSC, measuring the tensile strength and the elongation to break, measuring the melt flow index and the distribution of the grain size. The used fishing nets may have a significant smell of fish from trimethyl amine and rancid smell from oxidized fatty acids. The smell will disappear under the production mainly because of the volatility of trimethyl amine. The fatty acids will be partly degraded under the production, and if there is a remaining part, they will act as plastisizers in polyethylene and polyamide with a minor influence on the strength of the product. In the steel plant the plastic covers of taifun wires are melted off with energy supply from an induction technology. The steel will afterwards be cut in pieces with length up to 1 meter. The capacity of the extrusion line is planned to be 24 ton per day 7 days per week, and on the steel line the capacity is planned to be 8 – 10 ton steel per day 5 days per week. The amount of used fishing equipment for that production will be approximately 40 ton per day. During 2015 another extrusion line will be ready allowing the doubling of the production.