Theoretical and experimental correlations of gas dissolution, diffusion, and thermodynamic properties in determination of gas permeability and selectivity in supported ionic liquid membranes

Supported ionic liquid membranes (SILMs) has the potential to be a new technological platform for gas/organic vapour separation because of the unique non-volatile nature and discriminating gas dissolution properties of room temperature ionic liquids (ILs). This work starts with an examination of gas dissolution and transport properties in bulk imidazulium cation based ionic liquids [C_nmim][NTf2] (n = 2.4, 6, 8.10) from simple gas H₂, N₂, to polar CO₂, and C₂H₆, leading to a further analysis of how gas dissolution and diffusion are influenced by molecular specific gas-SILMs interactions, reflected by differences in gas dissolution enthalpy and entropy. These effects were elucidated again during gas permeation studies by examining how changes in these properties and molecular specific interactions work together to cause deviations from conventional solution–diffusion theory and their impact on some remarkably contrasting gas perm-selectivity performance. The experimental perm-selectivity for all tested gases showed varied and contrasting deviation from the solution–diffusion, depending on specific gas-IL combinations. It transpires permeation for simpler non-polar gases (H₂, N₂) is diffusion controlled, but strong molecular specific gas-ILs interactions led to a different permeation and selectivity performance for C₂H₆ and CO₂. With exothermic dissolution enthalpy and large order disruptive entropy, C₂H₆ displayed the fastest permeation rate at increased gas phase pressure in spite of its smallest diffusivity among the tested gases. The C₂H₆ gas molecules “peg” on the side alkyl chain on the imidazulium cation at low concentration, and are well dispersed in the ionic liquids phase at high concentration. On the other hand strong CO₂-ILs affinity resulted in a more prolonged “residence time” for the gas molecule, typified by reversed CO₂/N₂ selectivity and slowest CO₂ transport despite CO₂ possess the highest solubility and comparable diffusivity in the ionic liquids. The unique transport and dissolution behaviour of CO₂ are further exploited by examining the residing state of CO₂ molecules in the ionic liquid phase, which leads to a hypothesis of a condensing and holding capacity of ILs towards CO₂, which provide an explanation to slower CO₂ transport through the SILMs. The pressure related exponential increase in permeations rate is also analysed which suggests a typical concentration dependent diffusion rate at high gas concentration under increased gas feed pressure. Finally the strong influence of discriminating and molecular specific gas-ILs interactions on gas perm-selectivity performance points to future specific design of ionic liquids for targeted gas separations.

Aggregation behavior in water of new imidazolium and pyrrolidinium alkycarboxylates protic ionic liquids

A novel class of anionic surfactants was prepared through the neutralization of pyrrolidine or imidazole by alkylcarboxylic acids. The compounds, namely the pyrrolidinium alkylcarboxylates ([Pyrr][CnH2n+1COO]) and imidazolium alkylcarboxylates ([Im][CnH2n+1COO]), were obtained as ionic liquids at room temperature. Their aggregation behavior has been examined as a function of the alkyl chain length (from n = 5 to 8) by surface tensiometry and conductivity. Decreases in the critical micelle concentration (cmc) were obtained, for both studied PIL families, when increasing the anionic alkyl chain length (n). Surprisingly, a large effect of the alkyl chain length was observed on the minimum surface area per surfactant molecule (Amin) and, hence the maximum surface excess concentration (Gmax) when the counterion was the pyrrolidinium cation. This unusual comportment has been interpreted in term of a balance between van der Waals and coulombic interactions. Conductimetric measurements permit determination of the degree of ionization of the micelle (a) and the molar conductivity (?M) of these surfactants as a function of n. The molar conductivities at infinite dilution in water (?8) of the [Pyrr]+ and [Im]+ cations have been then determined by using the classical Kohlraush equation. Observed change in the physicochemical, surface, and micellar properties of these new protonic ionic liquid surfactants can be linked to the nature of the cation. By comparison with classical anionic surfactants having inorganic counterions, pyrrolidinium alkylcarboxylates and imidazolium alkylcarboxylates exhibit a higher ability to aggregate in aqueous solution, demonstrating their potential applicability as surfactant.

ME and Julie:a study in narrative of illness experience and therapy in a Myalgic Encephalomyelitis sufferer

This article uses what Atkinson and Walmsley (1997) refer to as an ‘autobiographical account’ to explore the themes and relationships between narrative, illness experience and therapy in a Myalgic Encephalomyelitis (ME) sufferer. Julie is a chronic ME sufferer, having lived with ME for the past 12 years. Her life-story over those years, as she presents it, casts our attention to the intrinsically personal nature of her ‘illness experience’ and to her distinctively artistic therapeutic responses to her condition. Julie’s autobiographical narrative reveals how ME has penetrated both her body and her sense of self, her limbs as well as her dreams; as though it were a parasite feeding off her fight to regain health. In terms of narrative, Julie’s ME illness progresses from past to present, but never to the future which lies beyond contemplation. Despite this denial of the future, Julie does think of ME as a liminal phase which is to be coped through. As both spatial object and temporal event, Julie conceptualises her ME variously, dealing with it on a day-to-day basis, increasingly turning to landscape painting as a form of escapism which parallels her former physical outward bound activities. This personal therapy, so this article concludes, constitutes both narrative performance and narrative text (as canvas), both of which can only cautiously be independently interpreted by the (inter)viewer.

Family-based associations in measures of psychological distress and quality of life in a cardiac screening clinic for inheritable cardiac diseases: a cross-sectional study

BACKGROUND: Family-based cardiac screening programmes for persons at risk for genetic cardiac diseases are now recommended. However, the psychological wellbeing and health related quality of life (QoL) of such screened patients is poorly understood, especially in younger patients. We sought to examine wellbeing and QoL in a representative group of adults aged 16 and over in a dedicated family cardiac screening clinic.

METHODS: Prospective survey of consecutive consenting patients attending a cardiac screening clinic, over a 12 month period. Data were collected using two health measurement tools: the Short Form 12 (version 2) and the Hospital Anxiety and Depression Scale (HADS), along with baseline demographic and screening visit-related data. The HADS and SF-12v.2 outcomes were compared by age group. Associations with a higher HADS score were examined using logistic regression, with multi-level modelling used to account for the family-based structure of the data.

RESULTS: There was a study response rate of 86.6%, with n=334 patients providing valid HADS data (valid response rate 79.5%), and data on n=316 retained for analysis. One-fifth of patients were aged under 25 (n=61). Younger patients were less likely than older to describe significant depression on their HADS scale (p<0.0001), although there were overall no difference between the prevalence of a significant HADS score between the younger and older age groups (18.0% vs 20.0%, p=0.73). Significant positive associates of a higher HADS score were having lower educational attainment, being single or separated, and being closely related to the family proband. Between-family variance in anxiety and depression scores was greater than within-family variance.

CONCLUSIONS: High levels of anxiety were seen amongst patients attending a family-based cardiac screening clinic.Younger patients also had high rates of clinically significant anxiety. Higher levels of anxiety and depression tends to run in families, and this has implications for family screening and intervention programmes.

Applying imagined contact to improve physiological responses in anticipation of intergroup interactions and the perceived quality of these interactions

This experiment (N 5 49) is the first to show that imagined contact can bufferanticipatory physiological responses to future interactions, and improve the qualityof these interactions. Participants imagined a positive interaction with a person withschizophrenia, or in a control condition, a person who did not have schizophrenia. They then interacted with a confederate whom they believed had schizophrenia. Participants in the imagined contact condition reported more positive attitudes andless avoidance of people with schizophrenia, displayed smaller anticipatory physio-logical responses, specifically smaller changes in interbeat interval and skin conduct-ance responses, and had a more positive interaction according to the confederate.These findings support applying imagined contact to improve interactions with people with severe mental illnesses.

The role of the seed bank in recovery of temperate heath and blanket bog following wildfires

Questions - Are the germinable seed banks of upland heath and blanket bog reduced following wildfires? Are some species at particular risk? Do the impacts of wildfires on seed banks differ between heathlands and blanket bog?

Location - Northern Ireland, United Kingdom.

Methods - Vegetation surveys and seed bank sampling were conducted in 2012 at burned and unburned areas within six upland sites where large wildfires had occurred during spring 2011. Differences in seedling abundance, species richness and Jaccard similarity indices between burned and unburned areas were compared using GLMMs. Differences in the community composition were examined using pRDA.

Results - In total, 24 of the 51 species in the vegetation were detected in the germinable seed bank. Species richness and the abundance of seedlings other than Calluna vulgaris were lower in areas where wildfires had occurred. Species composition of both germinable seed banks and vegetation differed between burned and unburned areas within sites; with negative associations between burned areas and some key indicator species including Drosera rotundifolia, Eriophorum vaginatum, Empetrum nigrum, Narthecium ossifragum and Trichophorum germanicum. We did not find any evidence of significant interactions between burning and habitat, suggesting that wildfires had similar impacts on each species regardless of the habitat in which they occurred.

Conclusions - This study differs from other UK studies in that it examines impacts of wildfires at sites that have not been previously intensively managed by burning. In particular, we highlight potential impacts on N. ossifragum and D. rotundifolia, which are key components of the upland flora and, to our knowledge, were not present in previous UK studies.