Investigating nano-structured domains within ionic liquids: the effect of cation change on thermal equilibrium and relaxation of spiropyran and spirooxazine.

The established belief that ionic liquids (ILs) behave as homogenous solvents such as that observed in molecular solvents has been challenged.1, 2 Previous use of solvatochromic probe dyes has allowed for the traditional parameter of ‘polarity’ to be determined.3 These values were compared to the kinetics of the photochromic spirocyclic compounds spirooxazine (SO) and spiropyran (SP). The nature of SO substituents limit the ability of hydrogen bond formation and so relies primarily on electrostatic interactions with the solvent system. Such an increase in solute freedom would be expected to increase the ability of the molecules to dissociate and migrate within the solvent system. A polarity-kinetic relationship for spirocyclic compounds has been established in molecular solvents with increasing polarity exhibiting decreased rates of thermal relaxation from the coloured merocyanine (MC) form to the spiro (SO/SP) form.4 However, thermal relaxation of SO in ionic liquids fails to present a correlation between polarity and kinetics. Kinetic studies were further enhanced by analysis of the relaxation process using thermodynamic parameters of activation. Previous studies have (primarily molecular modelling) proposed that ionic liquids possess a structured in-homogenous structure containing distinct areas of polar and non-polar regions.5 The probe dyes used to examine parameters such as hydrogen bonding (Kamlet-Taft) and polarity (ET30) may only examine a particular region in the solvent. This means that the probe molecules may solvate in one region while compounds such as SO may interact in another region completely and therefore not allow for correlation of polarity to thermal relaxation rates observed. The closed form is a neutral compound exhibiting non-polar characteristics. MC, due to its zwitterionic nature, is in contrast highly polar. We believe that the size and ratio of polar to non-polar regions may be a critical factor in the process of SO thermal relaxation. Increasing non-polar regions may encourage the SO form by shifting equilibrium and encouraging migration and facilitate enhanced closure of MC within the solvent system. Thermal relaxation of SO may therefore allow for confirmation of the theory of IL structuring. Due to the large range of ILs possible, a correlation in structural effects and a quantifiable change may aid in a more detailed understanding of ILs and facilitate customisability of the liquids to meet specific polarity/solvation requirements

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

Virtuous citizens: Pentecostal social activism in an age of suspicion

Through social activism Nigerian Pentecostals in London are carving out a space in society and making a claim for public recognition says Simon Coleman

Effects of low incubation temperatures on the bactericidal activity of anti-tuberculosis drugs

OBJECTIVES: to explore the effect of low incubation temperatures and the consequent slowing of bacterial metabolism on the bactericidal action of anti-tuberculosis drugs against Mycobacterium tuberculosis. METHODS: counting of surviving bacteria during exposure of static cultures to 1 mg/L isoniazid, 2 mg/L rifampicin, 0.5 or 2 mg/L TMC207 and 40 or 160 mg/L pyrazinamide, usually for periods of 21 days at temperatures of 37, 25, 22, 19, 16 or 8°C. RESULTS: the bactericidal activities of isoniazid and rifampicin were progressively reduced at 25 and 22°C, and were minimal at lower temperatures. TMC207 was immediately bactericidal at 37°C, in contrast to the early static phase reported with log phase cultures, and showed less change in activity as incubation temperatures were reduced than did rifampicin or isoniazid. Pyrazinamide was more bactericidal when incubation temperatures were reduced below 37°C and when the static seed cultures were most dormant. CONCLUSIONS: these results can be explained by the surmise that at low temperatures bacterial energy is at a low level with only just sufficient ATP to maintain homeostasis, making the bacteria more susceptible to the blocking of ATP synthesis by TMC207. Insufficient ATP at low temperature would also hinder the export of pyrazinoic acid, the toxic product of the pro-drug pyrazinamide, from the mycobacterial cell by an inefficient efflux pump that requires energ

Next generation analytical platforms for environmental sensing: new technologies for old problems

Existing platforms for monitoring of nutrient levels (phosphates, nitrates etc) and pathogens (E. coli) in water bodies are often prohibitively expensive (>€20k) due to the use of conventional sample/liquid handling which results in bulky and labour intensive (servicing and maintenance) devices. As a consequence, this results in monitoring strategies that suffer from a lack of sampling frequency and deployment scale. With outbreaks of waterborne illnesses are still commonly reported in Europe e.g Cryptosporidium, Galway, Ireland, 2008 and the need for the development of real-time monitoring platforms for early warning of potential health risks from waterborne pathogens, particularly in the food industry e.g water as a potential source of E. coli contamination in Germany and Europe, 2011, there is a clear need for advancement of available technologies. To address these challenges, the NAPES project proposes the development of low cost, autonomous system for environmental sensing in the aqueous environment. This project will investigate ways to deliver revolutionary advances in liquid/sample handling combined with new approaches to performing sensitive in-situ analytical measurements. The goal is to drive down the unit cost of these instruments by orders of magnitude to levels that can create a tipping point, at which the technology becomes ubiquitous. The project brings together a team of 8 participants; Dublin City University (IE), Eindhoven University of Technology (NL), Curie Institute (FR), CIC Microgune (ES), T.E Laboratories (IE), Williams Industrial services Ltd (UK), University of Milan (IT) and Aquila Biosciences Ltd (IE) and will integrate several innovative methods of fluid handling (microfluidic channels incorporating light actuated valves), pre-concentration (functionalised magnetic beads) and detection (phantom surfaces and lectin functionalised surfaces) to produce the next generation in water quality assessment. It is hoped that these new technologies will help produce affordable and fully deployable platforms that will increase sampling frequency and potentially the accuracy of detection through increased sample volume throughput and sensitive detection systems. The drive towards more effective water treatment will result in a demand for more strenuous measurement of key quality parameters, such as concentrations of key contaminants, to monitor improvements in treatment processes. This necessitates the development of reliable measurement systems to determine such parameters as a means of gauging the success of optimisation of these processes and highlighting areas where improvements may be required. The following talk will introduce the NAPES project, its consortium, the project’s objectives and summarise initial data from each of the on-going research streams that showcase the latest technologies begin developed within the project to achieve this goal. As part of the Nano4water cluster, NAPES hopes to contribute to increased citizen awareness and a contribution to increasing standards in water quality assessment within the EU

Investigating nano-structuring within imidazolium ionic liquids: A thermodynamic study using photochromic molecular probes

Following previous studies involving the thermal relaxation of spirocyclic compounds we extended our studies to investigate the formation of nano-structured domains in ionic liquids (ILs). Two compounds, spiropyran (BSP) and spirooxazine (SO) were added to imidazolium cation based ionic liquids with increasing chain lenghts (C2 –C12). Increasing side-chain length was found to have only minor effects on the rate of thermal relaxation of BSP and SO. BSP was found to be a suitable probe molecule as linear correlations in parameters were observed for this compound. This is believed to be due to the fact that BSP-IL interactions were based on hydrogen bonding between MCBSP and the cation compared to MCSO which is limited to electrostatic interactions thus enhancing the sensitivity of MCBSP to the charged polar regions. Increasing the side-chain of the cation resulted in slight increases in MC-BSP activation energy from 96.93 kJ.mol-1 in [C4mIm][NTf2] to 105.27 kJ.mol-1 in [C12mIm][NTf2]. MC-BSP S‡ and H‡ values also increased with increasing side-chain. Expansion and dispersion of polar regions due to increasing non-polar interactions may be enhanced by introduction of the bulky probe molecule. The resulting reorganisation of the system produced positive entropies of activation, 13.79 J.K- 1.mol-1 for C4mIm to 46.15 J.K-1.mol-1 for C12mIm, following an increase in disorder due to probe dye closure from MC to BSP and migration of dye to regions of preferential solvation. The ability for spirocyclic compounds to form both polar and non-polar isomers resulted in the ability to analyse both solvent regions using a single probe dye. Ground state equilibrium, Ke, examined non-polar regions of the IL while equilibrium of activation, K‡, examined the polar regions. A linear response to side chain length to equilibrium of activation was believed to be due to the fact that polar regions were possibly expanding due to increasing influence of non-polar side chain interactions upon the over solvent structure. The result of such reordering and dispersion of polar regions reduces solvent-solute interactions which increases rate of MC-BSP relaxation

(Re-)Placing Pentecostalism: Swedish Mission and the idea of the Baltic

I draw on fieldwork based in the Word of Life Ministry, Sweden, to consider how these neo-Pentecostals have constructed the Baltic as a landscape of both action and imagination. One part of my argument states that we must see the ministry’s attitudes to Sweden and the wider Baltic region in terms of its desire to situate itself within Swedish revivalist history. I also argue, however, that we can fruitfully draw on Bakhtin’s notion of the ‘chronotope’ to trace how the Baltic constitutes a potent spatio-temporal context for the construction of a narrative which encourages Word of Life members to see their missionary role as being contained within, but also looking far beyond, the Baltic Sea region

Itinerant Ferromagnetism in an Atom Trap

We propose an experiment to explore the magnetic phase transitions in interacting fermionic Hubbard systems, and describe how to obtain the ferromagnetic phase diagram of itinerant electron systems from these observations. In addition signatures of ferromagnetic correlations in the observed ground states are found: for large trap radii (trap radius $R_T > 4$, in units of coherence length $\xi$), ground states are topological in nature -- a "skyrmion" in 2D, and a "hedgehog" in 3D.Comment: Final Published version. References adde

Are the Ultra-Faint Dwarf Galaxies Just Cusps?

We develop a technique to investigate the possibility that some of the recently discovered ultra-faint dwarf satellites of the Milky Way might be cusp caustics rather than gravitationally self-bound systems. Such cusps can form when a stream of stars folds, creating a region where the projected 2-D surface density is enhanced. In this work, we construct a Poisson maximum likelihood test to compare the cusp and exponential models of any substructure on an equal footing. We apply the test to the Hercules dwarf (d ~ 113 kpc, M_V ~ -6.2, e ~ 0.67). The flattened exponential model is strongly favored over the cusp model in the case of Hercules, ruling out at high confidence that Hercules is a cusp catastrophe. This test can be applied to any of the Milky Way dwarfs, and more generally to the entire stellar halo population, to search for the cusp catastrophes that might be expected in an accreted stellar halo.Comment: Accepted for publication in ApJ Letters. Minor revisions from version