Physico-chemical properties of ionic-liquid water mixtures

In order for Ionic Liquids (ILs) to be utilized to their full potential, it is necessary to have a complete understanding of their physical properties, including phase transitions temperatures1. We have previously reported into the extent of structuring of ILs using photochromic molecular probes, and investigated the appropriate IL water content to yield hydrated IL systems for analysis of polarity and to create environments suitable for effective enzyme activity 1,2,3. In this study we investigated interactions in hydrated ILs containing variable hydrophobic and hydrophilic regions through optical and thermal analysis. The enthalpies and phase transitions of the systems were compared, between the temperature range -50°C to +30°C for the ILs with varying degrees of hydration. Reichardtʼs dye was used as a molecular probe to monitor changes in interactions in the ILs as a function of temperature. Comparisons were made between ILs and for ILs with varying degrees of hydration. Spectroscopic studies were performed using Perkin Elmer UV-Visible Spectrometer and phase transitions monitored using a Perkin Elmer Differential Scanning Calorimeter. The ILs examined are; Trihexyltetradecylphosphonium Chloride [P6,6,6,14 Cl] Tributyl-tetradecylphosphonium Chloride, [P4,4,4,14 Cl], 1-Ethyl-methyl-3-imidazolium-ethyl Sulfate [Emim][EtSO4] and Trihexyltetradecylphosphonium Dicyanamide [P6,6,6,14 DCA]. 1. Robert Byrne, Simon Coleman, Simon Gallagher, and Dermot Diamond. Designer Molecular Probes for Phosphonium Ionic Liquids. Physical Chemistry Chemical Physics, 2010. 2. Kyoko Fujita, Douglas R. MacFarlane, Maria Forsyth, Masahiro Yoshizawa-Fujita, Kenichi Murata,† Nobuhumi Nakamura, and Hiroyuki Ohno*,Solubility and Stability of Cytochrome c in Hydrated Ionic Liquids: Effect of Oxo Acid Residues and Kosmotropicity, 2007. 3. SergeiV.DzyubaandRichardA.Bartsch,Expandingthepolarityrange of ionic liquids, Tetrehedron Letters, 2002

Myosin II Light Chain Phosphorylation Regulates Membrane Localization and Apoptotic Signaling of Tumor Necrosis Factor Receptor-1

Activation of myosin II by myosin light chain kinase (MLCK) produces the force for many cellular processes including muscle contraction, mitosis, migration, and other cellular shape changes. The results of this study show that inhibition or potentiation of myosin II activation via over-expression of a dominant negative or wild type MLCK can delay or accelerate tumor necrosis factor-α (TNF)-induced apoptotic cell death in cells. Changes in the activation of caspase-8 that parallel changes in regulatory light chain phosphorylation levels reveal that myosin II motor activities regulate TNF receptor-1 (TNFR-1) signaling at an early step in the TNF death signaling pathway. Treatment of cells with either ionomycin or endotoxin (lipopolysaccharide) leads to activation of myosin II and increased translocation of TNFR-1 to the plasma membrane independent of TNF signaling. The results of these studies establish a new role for myosin II motor activity in regulating TNFR-1-mediated apoptosis through the translocation of TNFR-1 to or within the plasma membrane

Physical and mechanical properties of phosphonium based poly(ionic liquids)

Currently for applications in materials science, there is a growing interest in Ionogels i.e. polymers with ionic liquids (ILs) integrated such that they retain their specific properties within the polymer/gel environment. However one disadvantage of ionogels is the leaching of the IL in the liquid phase1. To overcome this, ‘poly (ionic liquids) PILs, are gaining momentum in the literature. Interesting applications for the incorporation of PILs into polymers have been published such as ultrasensitive and selective chemiresistive CO2 sensors2, and potential applications in fuel cell technology as some reported PIL films, display very high ionic conductivities (exceeding 90 mS cm-1 at 100 oC and 75% relative humidity)3. However the range of possible monomeric IL structures is far greater than has so far been explored4 In recent years functional materials have been developed to respond to a wide variety of stimuli, but their use in practical macro-scale devices has been hindered by slow response times arising mainly due to the diffusion processes that typically govern polymer swelling/contraction. The scaling-down to microfluidic devices should improve response times, due to the improved surface-to-volume ratios of these actuators. At these dimensions, stimuli-responsive PIL materials could dramatically enhance the capabilities of micro-fluidic systems by allowing self-regulated flow control. In this study we synthesis, characterise and photopattern a family of PILs, Tributyl 4-Vinylbenzylphosphonium ([P4,4,4,4VB]+ ), Trihexyl 4-Vinylbenzylphosphonium ([P6,6,6,4VB]+) and Trihexyl-allyl phosphonium [P6,6,6,allyl]+ cations coupled with commonly found anions in the ionic liquid literature (chloride, dicyanamide and bis(trifluoromethylsulfonyl)imide). As one might expect varying the anion of the PIL gave varying behaviour (thermal stability and electrochemically). The resulting polymer gels from the PILs also gave drastic mechanical stability differences. Finally the synthesised polymer gels have been photo-structured to submicron resolution as both planar and 3D patterns employing both single and multi- photon polymerisation (MPP) techniques. These materials will form a platform for the next generation of sensors & actuators currently being developed

Thermophysiochemical properties of pure and water-saturated ionic liquids

We have previously reported into the extent of structuring in ILs using photochromic molecular probes1. In order for Ionic Liquids (ILs) to be fully utilized to their potential, it is necessary to have a complete understanding of their physical properties. In this study we investigated the thermophysical interactions in several pure and water-saturated ionic liquids being hydrophilic and hydrophobic in nature, namely 1-alkyl-3-methyl imidazolium and trihexyltetradecylphosphonium family of ILs. The density, viscosity and conductivity of pure and water-saturated imidazolium and phosphonium-based ILs were measured over a broad temperature. Moreover, interactive and binding energies of the studied imidazolium ILs in the presence of H2O molecules were calculated using Gaussian and compared with experimental Raman spectroscopy of the same imidazolium ILs, with and without the presence of saturated water

Temperature & pH triggered release characteristics of water/fluorescein from 1-ethyl-3-methylimidazolium ethylsulfate based ionogels.

A crosslinked Poly(N-isopropylacrylamide) ionogel encapsulating an ionic liquid exhibits improved transmittance properties, enhanced water uptake/release, greater thermal actuation behaviour and distinct solvatomorphology over its hydrogel equivalent. It was also found that the rate of release of fluorescein pre-loaded into membranes was considerably enhanced for ionogels compared to equivalent hydrogels, and could be triggered through changes in pH and temperature

Environmental regulation in transition: Policy officials’ views of regulatory instruments and their mapping to environmental risks

This study re-analysed 14 semi-structured interviews with policy officials from the UK Department for Environment, Food and Rural Affairs (Defra) to explore the use of a variety of regulatory instruments and different levels of risk across 14 policy domains and 18 separately named risks. Interviews took place within a policy environment of a better regulation agenda and of broader regulatory reform. Of 619 (n) coded references to 5 categories of regulatory instrument, ‘command and control’ regulation (n = 257) and support mechanisms (n = 118) dominated the discussions, with a preference for ‘command and control’ cited in 8 of the policy domains. A framing analysis revealed officials' views on instrument effectiveness, including for sub-categories of the 5 key instruments. Views were mixed, though notably positive for economic instruments including taxation, fiscal instruments and information provision. An overlap analysis explored officials' mapping of public environmental risks to instrument types suited to their management. While officials frequently cite risk concepts generally within discussions, the extent of overlap for risks of specific significance was low across all risks. Only ‘command and control’ was mapped to risks of moderate significance in likelihood and impact severity. These results show that policy makers still prefer ‘command and control’ approaches when a certainty of outcome is sought and that alternative means are sought for lower risk situations. The detailed reasons for selection, including the mapping of certain instruments to specific risk characteristics, is still developing

History and modes of star formation in the most active region of the Small Magellanic Cloud, NGC 346

We discuss the star formation history of the SMC region NGC 346 based on Hubble Space Telescope images. The region contains both field stars and cluster members. Using a classical synthetic CMD procedure applied to the field around NGC 346 we find that there the star formation pace has been rising from a quite low rate 13 Gyr ago to \approx 1.4 \times 10^{-8} Mo yr^{-1}pc^{-2} in the last 100 Myr. This value is significantly higher than in other star forming regions of the SMC. For NGC 346 itself, we compare theoretical and observed Color-Magnitude Diagrams (CMDs) of several stellar sub-clusters identified in the region, and we derive their basic evolution parameters. We find that NGC 346 experienced different star formation regimes, including a dominant and focused "high density mode", with the sub-clusters hosting both pre-main sequence (PMS) and upper main sequence (UMS) stars, and a diffuse "low density mode", as indicated by the presence of low-mass PMS sub-clusters. Quantitatively, the star formation in the oldest sub-clusters started about 6 Myr ago with remarkable synchronization, it continued at high rate (up to 2 \times 10^{-5} Mo yr^{-1} pc^{-2}) for about 3 Myr and is now progressing at a lower rate. Interestingly, sub-clusters mainly composed by low mass PMS stars seem to experience now the first episode of star formation, following multi-seeded spatial patterns instead of resulting from a coherent trigger. Two speculative scenarios are put forth to explain the deficiency of UMS stars: the first invokes under-threshold conditions of the parent gas; the second speculates that the initial mass function (IMF) is a function of time, with the youngest sub-clusters not having had sufficient time to form more massive stars.Comment: 17 pages. Accepted for publication in A

Social Anxiety Symptoms and Suicidal Ideation in a Clinical Sample of Early Adolescents: Examining Loneliness and Social Support as Longitudinal Mediators

Recent research has shown that social anxiety may be related to increased risk for suicidal ideation in teens, although this research largely has been cross-sectional and has not examined potential mediators of this relationship. A clinical sample of 144 early adolescents (72 % female; 12–15 years old) was assessed during psychiatric inpatient hospitalization and followed up at 9 and 18 months post-baseline. Symptoms of social anxiety, depression, suicidal ideation, loneliness, and perceived social support were assessed via structured interviews and self-report instruments. Structural equation modeling revealed a significant direct relationship between social anxiety symptoms at baseline and suicidal ideation at 18 months post-baseline, even after controlling for baseline depressive symptoms and ideation. A second multiple mediation model revealed that baseline social anxiety had a significant indirect effect on suicidal ideation at 18 months post-baseline through loneliness at 9 months post-baseline. Social anxiety did not have a significant indirect effect on suicidal ideation through perceived social support from either parents or close friends. Findings suggest that loneliness may be particularly implicated in the relationship between social anxiety and suicidality in teens. Clinicians should assess and address feelings of loneliness when treating socially anxious adolescents