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

Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique

Phase variance-based motion contrast imaging is demonstrated using a spectral domain optical coherence tomography system for the in vivo human retina. This contrast technique spatially identifies locations of motion within the retina primarily associated with vasculature. Histogram-based noise analysis of the motion contrast images was used to reduce the motion noise created by transverse eye motion. En face summation images created from the 3D motion contrast data are presented with segmentation of selected retinal layers to provide non-invasive vascular visualization comparable to currently used invasive angiographic imaging. This motion contrast technique has demonstrated the ability to visualize resolution-limited vasculature independent of vessel orientation and flow velocity

Algorithm for Atmospheric Corrections of Aircraft and Satellite Imagery

A simple and fast atmospheric correction algorithm is described which is used to correct radiances of scattered sunlight measured by aircraft and/or satellite above a uniform surface. The atmospheric effect, the basic equations, a description of the computational procedure, and a sensitivity study are discussed. The program is designed to take the measured radiances, view and illumination directions, and the aerosol and gaseous absorption optical thickness to compute the radiance just above the surface, the irradiance on the surface, and surface reflectance. Alternatively, the program will compute the upward radiance at a specific altitude for a given surface reflectance, view and illumination directions, and aerosol and gaseous absorption optical thickness. The algorithm can be applied for any view and illumination directions and any wavelength in the range 0.48 micron to 2.2 micron. The relation between the measured radiance and surface reflectance, which is expressed as a function of atmospheric properties and measurement geometry, is computed using a radiative transfer routine. The results of the computations are presented in a table which forms the basis of the correction algorithm. The algorithm can be used for atmospheric corrections in the presence of a rural aerosol. The sensitivity of the derived surface reflectance to uncertainties in the model and input data is discussed

The Administration\u27s Program for Economic Recovery : Theory and Evidence

The economic recovery program proposes to inject about $100 billion into the aggregate spending stream while simultaneously reducing the inflation rate. Careful analysis of estimates of the supply response to tax rate reductions and deregulation show that output increases will not balance the increased demand. Savings rates several times historic levels are thus necessary not only to reduce inflation, but even to prevent the program from worsening inflation. Recent evidence indicates that none of the scenarios most often mentioned as producing the requisite savings hold much promise

Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]- anion

The photo-, thermo- and solvatochromic properties of 2,3-dihydro-10,30,30-trimethyl-6-nitrospiro- [1-benzopyran-2,20-1H-indole] (BSP-NO2) were studied in ILs containing the anion [NTf2]- by UV-Vis absorption spectroscopy, ab initio molecular orbital theory and density functional theory (DFT) calculations. It was found that the kinetics and thermodynamics of the BSP-NO2 MC (merocyanine) equilibrium was sensitive to the nature of the cation. It was also observed that the imidazolium cation can form a through-space orbital interaction with the MC isomer, rather than a simple electrostatic interaction, thus preventing the MC conversion back to the BSP-NO2 isomer. The BSP-NO2 MC equilibrium thus serves as a model system for studying modes of interaction of the cations in ionic liquids

Portable Lab-on-a-Disc system integrating photo-switchable micro-valves for in-situ aquatic environmental monitoring

This work describes the first use of a portable centrifugal microfluidic analysis system (CMAS) for on-site lab-on-a-disc water quality monitoring. The centrifugal microfluidic platform designed for the detection of nitrite in multiple water samples incorporates photo-switchable microvalves, which are easily controlled using white light irradiation. Calibration of the CMAS system resulted in a linear response that obeys the Beer-Lambert Law. Excellent correlation of results between the CMAS device and a standard UV-Vis spectrophotometer were obtained

Stimuli Responsive Ionogels for Sensing Applications - An Overview.

This overview aims to summarise the exiting potential of “Ionogels” as a platform to develop stimuli responsive materials. Ionogels are a class of materials that contain an Ionic Liquid (IL) confined within a polymer matrix. Recently defined as “a solid interconnected network spreading throughout a liquid phase”, the ionogel therefore combines the properties of both its solid and liquid components. ILs are low melting salts that exist as liquids composed entirely of cations and anions at or around 100 0C. Important physical properties of these liquids such as viscosity, density, melting point and conductivity can be altered to suit a purpose by choice of the cation / anion. Here we provide an overview to highlight the literature thus far detailing the encapsulation of IL and responsive materials within these polymeric structures. Exciting applications in the areas of optical and electrochemical sensing, solid state electrolytes and actuating materials shall be discussed. Keywords: Stimuli Responsive Polymers; Ionogels; Ionic Liquids; Hybrid Materials; Molecular Photoswitches; Solid State Electrolytes

Next generation autonomous analytical platforms for remote environmental monitoring

The Marie Curie ATWARM (Advanced Technologies for Water Management) project aims at the development of technologies to treat and manage drinking water. Within the ATWARM project there are 16 scientist working on different technologie aspects and processes to clean water from pollutants. In order to successfully treat water one needs reliable and rapid information on the environment state and potential alarming events. This information needs to be available in real time. Utilizing wireless sensor networks is the key to obtaining such monitoring capabilities. In the ideal case, information is gathered by the remote sensors and transmitted to headquarters for analysis. Unfortunately, such devices that are available today are big, very expensive and need frequent maintenance. Therefore they are not suitable for large scale and remote deployment. In order to be able to build cheap, robust and autonomous sensors one needs to develop smart materials. These materials are capable of reacting to an external stimulus and perform their given task. Current research involves polymers that bend or actuate reversibly after irridation with light or in some cases after applying magnetic fields. Fluidic sensors (required in every type of water analysis) incorporating such material in a form of pumps and valves would require minimum power. The light can come from an inexpensive, low power drain LED diode and magnetic fields from permanent magnets. The sensor system already developed at the National Centre for Sensor Research (NCSR), Dublin City University is capable of sampling, managing chemical reactants required for the chemical analysis, performing the analysis with light emitting diodes and transmitting the information through wireless means to the controller unit. However it is still quite bulky, batteries lasts for 2 weeks and the manufacturing cost is still high for mass deployment. By using the described smart materials this device is expected to function for up to 6 months without maintenance and projected costs are estimated at less than 100 euro. This research brings together scientists from fields such as computer science, electronics, engineering, chemistry and material science. Working in such an environment is greatly improving one’s interdisciplinary skills and team spirit along with innovative thinking necessary when applying fundamental science in functional devices such as sensors. This research is a great opportunity and adventure for the involved people but also the technology being developed will greatly enhance our environment monitoring capabilities. Efficient and successful environment protection and successful water management is important in all aspects of life