How do polymerized room-temperature ionic liquid membranes plasticize during high pressure CO2 permeation?

Room-temperature ionic liquids (RTILs) are a class of organic solvents that have been explored as novel media for CO2 separations. Polymerized RTILs (poly(RTILs)) can be synthesized from RTIL monomers to form dense, solid gas selective membranes. It is of interest to understand the permeation properties under single gas and mixed gas conditions at elevated pressure of CO2. The ionic nature of the polymers may result in tight arrangements between the oppositely charged ionic domains in the poly(RTIL) eventually preventing the membrane from excessive swelling and deterioration of its performance at increased pressure and/or temperature. In this work we characterize the permeation behaviour of three different poly(RTILs) at single and mixed gas pressures up to 40bar and over a temperature range from T=10-40°C. We find that CO2 is an equally strong plasticizer in single gas as well as mixed gas experiments: the permeability of CO2 increases by more than 60% over a pressure range of 40bar. Methane does not plasticize the poly(RTIL) by itself in single gas experiments, however the presence CO2 accelerates its transport by more than 250%. The plasticization effect of CO2 is fully reversible on the time scale of the diffusional processes. Even though the poly(RTILs) are glassy in nature, the plasticization behaviour is distinctly different from regular glassy polymers such as polyimides, polysulfones or polycarbonates due to the reversibility of swelling extent. Tailoring the length of the side chain of poly(RTIL) indicates that short side chains suppress plasticization and acceleration of the methane permeability up to a pressure of 10bars CO2: longer side chains however do not. This suggests the interpretation that a molecular energy balance of ionic attraction and swelling-induced relaxation exists: however, the swelling-induced relaxations overrule the ionic interaction

Is self-medication with antibiotics in Europe driven by prescribed use?

Background: Self-medication with antibiotics may increase the risk of inappropriate use and the selection of resistant bacteria. One of the triggers for using self-medication may be past experience with antibiotics prescribed by health professionals. We examined the association between prescribed use and self-medication with antibiotics. Methods: A population survey was conducted in 19 European countries, covering 15 548 respondents. Multinomial logistic regression analysis was used to study the relationship between prescribed use and self-medication for all symptoms/diseases and for upper respiratory tract infections (URTIs). Results: The association between prescribed use and self-medication was modified by source of self-medication, region in Europe and education. This association was consistently stronger for self-medication from leftovers than from other sources, primarily directly from a pharmacy. It was stronger also for respondents from Northern/Western Europe than respondents from Eastern Europe and Southern Europe and those with low education. Prescribed use for URTIs (minor ailments such as throat symptom, influenza, etc.) increased the likelihood of self-medication with leftover antibiotics for these symptoms/diseases in all European regions. Conclusions: Our study shows consistent associations between prescribed use and self-medication with antibiotics from leftovers, but has not been able to support the hypothesis that self-medication from other sources than leftovers is triggered by earlier prescribed use. Preventing leftovers may be one effective way of preventing self-medication. This can be achieved by ensuring that the amount dispensed corresponds to the amount prescribed, by educating patients and by making doctors aware that prescribing for minor ailments may increase the risk of self-medication for such ailments