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Sample records for calculate multi-species ionic

  1. Comparison between the Gauss' law method and the zero current method to calculate multi-species ionic diffusion in saturated uncharged porous materials

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2010-01-01

    difference of the two types of potentials, that is, the streaming electrical potential and the electrical field is carefully examined. A novel numerical method based on the finite element approach is established for the zero current method case. The proposed numerical method uses the direct calculation......There exist, mainly, two different continuum approaches to calculate transient multi species ionic diffusion. One of them is based on explicitly assuming a zero current in the diffusing mixture together with an introduction of a streaming electrical potential in the constitutive equations...... of the coupled set of equation in favor of the staggering approach. A one step truly implicit time stepping scheme is adopted together with an implementation of a modified Newton-Raphson iterational scheme for search of equilibrium at each considered time step calculation. Results from the zero current case...

  2. Numerical Calculations of the Effect of Moisture Content and Moisture Flow on Ionic Multi-Species Diffusion in the Pore Solution of Porous Materials

    DEFF Research Database (Denmark)

    Johannesson, Björn; Hosokawa, Yoshifumi; Yamada, Kazuo

    2009-01-01

    A method to analyse and calculate concentration profiles of different types of ions in the pore solution of porous materials such as concrete subjected to external wetting and drying is described. The equations in use have a solid theoretical meaning and are derived from a porous media technique...... and the moisture content are solved simultaneously using an implicit finite element technique, in order to avoid numerical oscillations. Important verified material behaviours are included in the model, such as the convective flow of ionic species due to moisture flow, the effect of the moisture...

  3. Multi-species Ionic Diffusion in Concrete with Account to Interaction Between Ions in the Pore Solution and the Cement Hydrates

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2007-01-01

    electron probe micro analysis (EPMA) data. A close agreement of the simulated results to measured data is found for the specific studied example. The model includes the ionic species Cl-, Na+, OH-, Ca2+, K+ and SO42- and solid phases with variable composition. From the EPMA measurements the total...... results concerning the multi-species action during chloride penetration. In the model the chemical interaction between ions in solids and in pore solution is assumed governed by simple ion exchange processes only. The drawback using this approach is that the chemical part is lacking important physical...

  4. Modeling of the Ionic Multi-Species Transport Phenomena in Electrokinetic Processes and Comparison with Experimental Results

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.

    2010-01-01

    A model to predict the transport of ionic species within the pore solution of porous materials, under the effect of an external electric field has been developed. A Finite Elements method was implemented and used for the integration of the Nernst-Plank equations for each ionic species considered....... Electrical neutrality was continuously assured in the model by the inclusion of the Poisson-Boltzmann equation to the system of governing equations. Voltage differences were applied across the sample as boundary conditions in order to evaluate the competition between diffusion and electromigration terms...... in the transport process. As a modification of a previous work, water equilibrium was reestablished between iterations in the numerical method and the pH value monitored. Simulations were conducted in order to visualize the acid and basic fronts advance, and to evaluate the use of a buffer substance...

  5. Modern ab initio valence bond theory calculations reveal charge shift bonding in protic ionic liquids.

    Science.gov (United States)

    Patil, Amol Baliram; Bhanage, Bhalchandra Mahadeo

    2016-06-21

    The nature of bonding interactions between the cation and the anion of an ionic liquid is at the heart of understanding ionic liquid properties. A particularly interesting case is a special class of ionic liquids known as protic ionic liquids. The extent of proton transfer in protic ionic liquids has been observed to vary according to the interacting species. Back proton transfer renders protic ionic liquids volatile and to be considered as inferior ionic liquids. We try to address this issue by employing modern ab initio valence bond theory calculations. The results indicate that the bonding in the cation and the anion of a prototypical ionic liquid, ethylammonium nitrate, is fundamentally different. It is neither characteristic of covalent/polar covalent bonding nor ionic bonding but rather charge shift bonding as a resonance hybrid of two competing ionic molecular electronic structure configurations. An investigation of other analogous protic ionic liquids reveals that this charge shift bonding seems to be a typical characteristic of protic ionic liquids while the ionic solid analogue compound ammonium nitrate has less charge shift bonding character as compared to protic ionic liquids. Further the extent of charge shift bonding character has been found to be congruent with the trends in many physicochemical properties such as melting point, conductivity, viscosity, and ionicity of the studied ionic liquids indicating that percentage charge shift character may serve as a key descriptor for large scale computational screening of ionic liquids with desired properties. PMID:27229870

  6. Multi-species integrative biclustering

    OpenAIRE

    Waltman, Peter; Kacmarczyk, Thadeous; Bate, Ashley R.; Kearns, Daniel B.; Reiss, David J.; Eichenberger, Patrick; Bonneau, Richard

    2010-01-01

    We describe an algorithm, multi-species cMonkey, for the simultaneous biclustering of heterogeneous multiple-species data collections and apply the algorithm to a group of bacteria containing Bacillus subtilis, Bacillus anthracis, and Listeria monocytogenes. The algorithm reveals evolutionary insights into the surprisingly high degree of conservation of regulatory modules across these three species and allows data and insights from well-studied organisms to complement the analysis of related ...

  7. An Increment Method of Calculation of Melting Temperatures of Ionic Crystals

    International Nuclear Information System (INIS)

    A new increment method for calculation of melting temperatures (Tm) of binary inorganic ionic crystalline compounds has been suggested. On the basis of rather simple mathematic relationship the Tm for the majority of these compounds can be defined by the accuracy of no less than 10%. (author)

  8. Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2007-01-01

    A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibrational...... spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C4mim][X]) salts. The rotational isomerism of the [C4mim]þ cation is described: the presence of anti and...... gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the ‘‘localized structure features’’ that apparently exist in ionic liquids are described. It is hoped that...

  9. Ionic liquid based lithium battery electrolytes: charge carriers and interactions derived by density functional theory calculations.

    Science.gov (United States)

    Angenendt, Knut; Johansson, Patrik

    2011-06-23

    The solvation of lithium salts in ionic liquids (ILs) leads to the creation of a lithium ion carrying species quite different from those found in traditional nonaqueous lithium battery electrolytes. The most striking differences are that these species are composed only of ions and in general negatively charged. In many IL-based electrolytes, the dominant species are triplets, and the charge, stability, and size of the triplets have a large impact on the total ion conductivity, the lithium ion mobility, and also the lithium ion delivery at the electrode. As an inherent advantage, the triplets can be altered by selecting lithium salts and ionic liquids with different anions. Thus, within certain limits, the lithium ion carrying species can even be tailored toward distinct important properties for battery application. Here, we show by DFT calculations that the resulting charge carrying species from combinations of ionic liquids and lithium salts and also some resulting electrolyte properties can be predicted. PMID:21591707

  10. Raman spectroscopy, ab-initio model calculations, and conformational, equilibria in ionic liquids

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    hoped that the structural resolving power of Raman spectroscopy will be appreciated by the reader, when used on crystals of known conformation and on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these inetrdisciplinary methods will be...... spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT- Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methyl-imidazolium ([C4C1Im]+X-) salts. The rotational isomerism of the [C4C1Im]+ cation is described: the presence of anti...... instrumentation ...... 311 12.3 Brief introduction to ab-initio model calculations .... 312 12.4 Case study on Raman spectroscopy and structure of imidazolium-based ionic liquids ..... 312 12.5 Raman spectra and structure of [C4C1Im]+ liquids ..... 315 12.6 Normal mode analysis and rotational isomerism of the [C4...

  11. SDPBS Web Server for Calculation of Electrostatics of Ionic Solvated Biomolecules

    OpenAIRE

    Jiang Yi; Xie Yang; Ying Jinyong; Xie Dexuan; Yu Zeyun

    2015-01-01

    The Poisson-Boltzmann equation (PBE) is one important implicit solvent continuum model for calculating electrostatics of protein in ionic solvent. We recently developed a PBE solver library, called SDPBS, that incorporates the finite element, finite difference, solution decomposition, domain decomposition, and multigrid methods. To make SDPBS more accessible to the scientific community, we present an SDPBS web server in this paper that allows clients to visualize and manipulate th...

  12. Correlation between Quantumchemically Calculated LUMO Energies and the Electrochemical Window of Ionic Liquids with Reduction-Resistant Anions

    Directory of Open Access Journals (Sweden)

    Wim Buijs

    2012-01-01

    Full Text Available Quantum chemical calculations showed to be an excellent method to predict the electrochemical window of ionic liquids with reduction-resistant anions. A good correlation between the LUMO energy and the electrochemical window is observed. Surprisingly simple but very fast semiempirical calculations are in full record with density functional theory calculations and are a very attractive tool in the design and optimization of ionic liquids for specific purposes.

  13. Thermodynamic Properties of Selected Homologous Series of Ionic Liquids Calculated Using Molecular Dynamics.

    Science.gov (United States)

    Červinka, Ctirad; Pádua, Agilio A H; Fulem, Michal

    2016-03-10

    This work presents a molecular dynamics simulation study concerning the thermodynamic data of ionic liquids (ILs) including phase change enthalpies, liquid phase densities, radial and spatial distribution functions, and diffusive properties. Three homologous series of ILs were selected for this study, namely, 1-alkyl-3-methylimidazolium tetrafluoroborates, hexafluorophosphates, and 1,1,2,2-tetrafluoroethanesulfonates, so that properties of 36 ILs are calculated in total. The trends of calculated properties are compared to available experimental data and thoroughly discussed in context of the homologous series. The calculated trends of the vaporization enthalpies within the series are supported by analyzing the structural properties of the ILs. An excellent agreement of calculated structural properties (liquid phase density) with the experimental counterparts is reached. The calculated enthalpic properties are overestimated considerably; thus, further development of the force fields for ILs is required. PMID:26848831

  14. Understanding microbial multi-species symbioses

    Directory of Open Access Journals (Sweden)

    Ines Aline Aschenbrenner

    2016-02-01

    Full Text Available Lichens are commonly recognized as a symbiotic association of a fungus and chlorophyll containing partner, either green algae or cyanobacteria, or both. The fungus provides a suitable habitat for the partner, which provides photosynthetically fixed carbon as energy source for the system. The evolutionary result of the self-sustaining partnership is a unique joint structure, the lichen thallus, which is indispensable for fungal sexual reproduction. The classical view of a dual symbiosis has been challenged by recent microbiome research, which revealed host-specific bacterial microbiomes. The recent results about bacterial associations with lichens symbioses corroborate their notion as a multi-species symbiosis. Multi-omics approaches have provided evidence for functional contribution by the bacterial microbiome to the entire lichen meta-organism while various abiotic and biotic factors can additionally influence the bacterial community structure. Results of current research also suggest that neighboring ecological niches influence the composition of the lichen bacterial microbiome. Specificity and functions are here reviewed based on these recent findings, converging to a holistic view of bacterial roles in lichens. Finally we propose that the lichen thallus has also evolved to function as a smart harvester of bacterial symbionts. We suggest that lichens represent an ideal model to study multi-species symbiosis, using the recentily available omics tools and other cutting edge methods.

  15. Effects of high ionic strength groundwaters on calculated equilibrium concentrations in the uranium-water-system

    International Nuclear Information System (INIS)

    The solubility of uranium in three model groundwaters has been calculated for a wide range of pH and oxidation conditions at 25 degrees Celcius. The Bronsted-Guggenheim approach has been used to obtain the Gibbs energies of transfer from water to saline groundwaters (I ≤ 3.6 mol·kg-1) for key ions including U022+. The Gibbs energies of other species were estimated from equilibrium constant data found in the literature. For reducing conditions, the solubility in highly saline waters differs little from the solubility in low ionic strength granitic groundwater. Good chemical thermodynamic data for uranium(VI) hydrolysis species in neutral and basic solution are not available. Thus, the uranium database, not medium effects, is the major source of uncertainties in the solubilities calculated for uranium in oxidizing and mildly reducing groundwaters. Extension of the calculations to groundwaters at higher temperatures is discussed

  16. Current understanding of multi-species biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong;

    2011-01-01

    Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually...... formed by multiple bacterial species. Conventional methods for bacterial cleaning, such as applications of antibiotics and/or disinfectants are often ineffective for biofilm populations due to their special physiology and physical matrix barrier. It has been estimated that billions of dollars are spent...... every year worldwide to deal with damage to equipment, contaminations of products, energy losses, and infections in human beings resulted from microbial biofilms. Microorganisms compete, cooperate, and communicate with each other in multi-species biofilms. Understanding the mechanisms of multi...

  17. On the calculation of single ion activity coefficients in homogeneous ionic systems by application of the grand canonical ensemble

    DEFF Research Database (Denmark)

    Sloth, Peter

    1993-01-01

    The grand canonical ensemble has been used to study the evaluation of single ion activity coefficients in homogeneous ionic fluids. In this work, the Coulombic interactions are truncated according to the minimum image approximation, and the ions are assumed to be placed in a structureless......, homogeneous dielectric continuum. Grand canonical ensemble Monte Carlo calculation results for two primitive model electrolyte solutions are presented. Also, a formula involving the second moments of the total correlation functions is derived from fluctuation theory, which applies for the derivatives of the...... individual ionic activity coefficients with respect to the total ionic concentration. This formula has previously been proposed on the basis of somewhat different considerations....

  18. [Multi-Species Biofilms in Ecology, Medicine, and Biotechnology].

    Science.gov (United States)

    Nozhevnikova, A N; Botchkova, E A; Plakunov, V K

    2015-01-01

    The structure, composition, and developmental patterns of multi-species biofilms are analyzed, as well as the mechanisms of interaction of their microbial components. The main methodological approaches used for analysis of multi-species biofilms, including omics technologies, are characterized. Environmental communities (cyanobacterial mats and methanotrophic communities), as well as typical multi-species communities of medical importance (oral cavity, skin, and gut microbiomes) are described. A special section deals with the role of multi-species biofilms in such biotechnological processes as wastewater treatment, heavy metal removal, corrosion control, and environmental bioremediation. PMID:26964353

  19. Method for calculating ionic and electronic defect concentrations in y-stabilised zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, F.W. [Risoe National Lab., Materials Research Dept., Roskilde (Denmark)

    1997-10-01

    A numerical (trial and error) method for calculation of concentration of ions, vacancies and ionic and electronic defects in solids (Brouwer-type diagrams) is presented. No approximations or truncations of the set of equations describing the chemistry for the various defect regions are used. Doped zirconia and doped thoria with simultaneous presence of protonic and electronic defects are taken as examples: 7 concentrations as function of oxygen partial pressure and/or water vapour partial pressure are determined. Realistic values for the equilibrium constants for equilibration with oxygen gas and water vapour, as well as for the internal equilibrium between holes and electrons were taken from the literature. The present mathematical method is versatile - it has also been employed by the author to treat more complex systems, such as perovskite structure oxides with over- and under-stoichiometry in oxygen, cation vacancies and simultaneous presence of protons. (au) 6 refs.

  20. Reestablishing Chicory into Multi-Species Perennial Pastures

    Science.gov (United States)

    Chicory (Cichorium intybus L.) has the potential to provide abundant, high quality forage during periods of drought stress, but poor persistence limits its usefulness in permanent pasture. This experiment compared the ability of three seeding methods to reestablish chicory into a grazed multi-specie...

  1. 77 FR 37656 - Multi-Species Habitat Conservation Plan

    Science.gov (United States)

    2012-06-22

    ... Statement in the Federal Register on February 22, 2008 (73 FR 9776). That document also announced a 30-day... Impact Statement, Siskiyou County, California in the Federal Register (74 FR 58602). The public review... 0648-XC011 Multi-Species Habitat Conservation Plan AGENCY: National Marine Fisheries Service...

  2. Calculation of the Hartree-Fock band structure in solid rare gases and ionic compounds - Application to the optical transitions

    International Nuclear Information System (INIS)

    The well-known 'augmented plane waves' method, for the calculation of electronic states in crystals, is first reviewed. A modification of this method in the case of insulators is then described, which treats exchange in the exact Hartree-Fock formulation, without use of the common free-electron approximation. The band structure of several rare gases (Ne, Ar) and ionic compounds (LiF, NaF, KF, LiCl, NaCl, KCl) has been calculated and discussed. The main point is the strong influence of correlation effects which must be taken into account before comparison between calculated and measured optical transitions. Such an improvement is obtained by including a local polarization potential in the one-electron Hamiltonian, leading to a good agreement of the theoretical transitions with the experimental ones. (author)

  3. Pressure dependence of magnetic coupling in ionic solids from ab initio cluster model calculations

    Science.gov (United States)

    Casanovas, Jordi; Illas, Francesc

    1994-11-01

    The dependence of the magnetic coupling constant, J, with the pressure has been studied by an ab initio cluster model approach in a typical ionic solid such as KNiF3. By computing J at different values of the lattice parameter R, we predict a power law of the form ‖J‖≊R-n with 10.5

  4. Theory of electromagnetic fluctuations for magnetized multi-species plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Roberto E., E-mail: roberto.navarro@ug.uchile.cl; Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Araneda, Jaime [Departamento de Física, Universidad de Concepción, Concepción 4070386 (Chile); Moya, Pablo S. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Department of Physics, Catholic University of America, Washington, D. C. 20064 (United States); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Valdivia, Juan A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro de Estudios Interdisciplinarios Básicos y Aplicados en Complejidad, CEIBA complejidad, Bogotá (Colombia)

    2014-09-15

    Analysis of electromagnetic fluctuations in plasma provides relevant information about the plasma state and its macroscopic properties. In particular, the solar wind persistently sustains a small but detectable level of magnetic fluctuation power even near thermal equilibrium. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we derive general expressions for the plasma fluctuations in a multi-species plasma following arbitrary distribution functions. This formalism, which generalizes and includes previous works on the subject, is then applied to the generation of electromagnetic fluctuations propagating along a background magnetic field in a plasma of two proton populations described by drifting bi-Maxwellians.

  5. Fluctuating hydrodynamics of multi-species reactive mixtures.

    Science.gov (United States)

    Bhattacharjee, Amit Kumar; Balakrishnan, Kaushik; Garcia, Alejandro L; Bell, John B; Donev, Aleksandar

    2015-06-14

    We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical master equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [Balakrishnan , Phys. Rev. E 89, 013017 (2014)]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same time, several problems with Langevin formulations of stochastic chemistry are identified, suggesting that future work should examine combining Langevin and master equation descriptions of hydrodynamic and chemical fluctuations. PMID:26071701

  6. Fluctuating hydrodynamics of multi-species reactive mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Amit Kumar; Donev, Aleksandar [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Balakrishnan, Kaushik [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192 (United States); Bell, John B. [Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2015-06-14

    We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical master equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [Balakrishnan , Phys. Rev. E 89, 013017 (2014)]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same time, several problems with Langevin formulations of stochastic chemistry are identified, suggesting that future work should examine combining Langevin and master equation descriptions of hydrodynamic and chemical fluctuations.

  7. Non-equivalence effects in cluster self-consistent calculations of ionic solids

    International Nuclear Information System (INIS)

    A simple model was used to analyse actual cluster calculations and an interpretation of the existence of central levels well separated from band levels is proposed for INDO Xα methods. The analysis shows that the convergence to the infinite solid through the use of a point charge boundary condition cannot in general eliminate this symmetry nonequivalence effect, which is related to the approximate treatment of two-electron interactions inherent to each kind of cluster method. For the INDO method a simple procedure is proposed to eliminate the effect. (Author)

  8. An atomistic model to calculate the core structure and energy of dislocations in ionic crystals. Part 2: Flexible boundary models

    International Nuclear Information System (INIS)

    A discussion is given of various flexible boundary models that can be used to improve upon the atomistic rigid boundary calculation of dislocation energetics in ionic crystals. A flexible boundary method due to Sinclair (Flex-PT) and a method due to Hoagland, Gehlen and Hirth (Flex-II) are described in detail. These have been used to calculate the core structure, volume of expansion and strain energy of the a/2[110] edge dislocaton in MgO. Comparison between these two models and the rigid boundary model shows that Flex-II is superior both in terms of efficiency and accuracy. Thus Flex-II uses only 20% of the computing time required by the rigid boundary model. Essential findings are as follows. The configuration of the region closest to the core (within approximately 4b from the dislocation line) is essentially the same as that obtained previously from the rigid boundary model. The strain field in regions far from the core can be expressed as a sum of the Volterra field and two linear dipole expansion fields. The presence of the dislocation causes a volume expansion of the entire crystal of approximately 1 atomic volumes/plane. (author)

  9. Theoretical Calculation of Absolute Radii of Atoms and Ions. Part 2. The Ionic Radii

    Directory of Open Access Journals (Sweden)

    Raka Biswas

    2003-05-01

    Full Text Available Abstract: The theoretical method of determination of absolute atomic size, discussed in Int. J. Mol. Sci. 2002, 3, 87-113, is exploited to calculate absolute radii of the ions whose experimental radii are published by Shanon. The computed radii are found to reproduce the expected periodic variation of size in periods and in groups and nicely reproduce the d-block and f-block contractions in the respective series. It is pointed out that experimental radii of d and f block transition metal ions make erroneous and misleading representation of the size behaviour of the respective series. A detailed comparative study of the crystal radii vis-à-vis the theoretical radii is reported. A rationale of the double hump curve of the experimental radii of 3 d-block transition metal ions is put forward in terms of the crystal field theory and Jahn-Teller distortion. The theoretical radii are exploited to calculate the diamagnetic susceptibility, polarizability and chemical hardness of the ions and compared with available experimental data. The fact of good agreement between the experimental and computed global hardness of ions and correct demonstration of d-block and f-block contraction by the computed radii are used as benchmark to test the validity of the values of the computed theoretical radii of the ions as their representative sizes. It is concluded that the theoretically computed radii of ions are visualizable size representation of ions and can be used as their absolute radii at the respective oxidation states.

  10. Non-covalent interactions in ionic liquid ion pairs and ion pair dimers: a quantum chemical calculation analysis.

    Science.gov (United States)

    Marekha, Bogdan A; Kalugin, Oleg N; Idrissi, Abdenacer

    2015-07-14

    Ionic liquids (ILs) being composed of bulky multiatomic ions reveal a plethora of non-covalent interactions which determine their microscopic structure. In order to establish the main peculiarities of these interactions in an IL-environment, we have performed quantum chemical calculations for a set of representative model molecular clusters. These calculations were coupled with advanced methods of analysis of the electron density distribution, namely, the quantum theory of atoms in molecules (QTAIM) and the non-covalent interaction (NCI; J. Am. Chem. Soc., 2010, 132, 6499) approaches. The former allows for profound quantitative characterization of non-covalent interactions between atoms while the latter gives an overview of spatial extent, delocalization, and relative strength of such interactions. The studied systems consist of 1-butyl-3-methylimidazolium (Bmim(+)) cations and different perfluorinated anions: tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (TFSI(-)). IL ion pairs and ion pair dimers were considered as model structures for the neat ILs and large aggregates. Weak electrostatic hydrogen bonding was found between the anions and the imidazolium ring hydrogen atoms of cations. Weaker but still appreciable hydrogen bonding was also noted for hydrogen atoms adjacent to the imidazolium ring alkyl groups of Bmim(+). The relative strength of the hydrogen bonding is higher in BmimTfO and BmimBF4 ILs than in BmimPF6 and BmimTFSI, whereas BmimTfO and BmimTFSI reveal higher sensitivity of hydrogen bonding at the different hydrogen atoms of the imidazolium ring. PMID:26059822

  11. A multi-species collisional operator for full-F gyrokinetics

    Energy Technology Data Exchange (ETDEWEB)

    Estève, D.; Garbet, X.; Sarazin, Y.; Grandgirard, V.; Cartier-Michaud, T.; Dif-Pradalier, G.; Ghendrih, P.; Latu, G.; Norscini, C. [CEA, IRFM, F-13108 St. Paul-lez-Durance cedex (France)

    2015-12-15

    A linearized multi-species collision operator has been developed for an efficient implementation in gyrokinetic codes. This operator satisfies the main expected properties: particle, momentum, and energy conservation, and existence of an H-theorem. A gyrokinetic version is then calculated, which involves derivatives with respect to the gyrocenter position, parallel velocity, and magnetic momentum. An isotropic version in the velocity space can be constructed for the specific problem of trace impurities colliding with a main species. A simpler version that involves derivatives with parallel velocity only has been developed. This reduced version has been implemented in the GYSELA gyrokinetic code, and is shown to comply with particle, momentum, and energy conservation laws. Moreover, the interspecies relaxation rates for momentum and energy agree very well with the theoretical values.

  12. Cosmological Hydrodynamics with Multi-Species Chemistry and Nonequilibrium Ionization and Cooling

    CERN Document Server

    Anninos, P; Abel, T; Norman, M L; Anninos, Peter; Zhang, Yu; Abel, Tom; Norman, Michael L.

    1996-01-01

    We have developed a method of solving for multi-species chemical reaction flows in non--equilibrium and self--consistently with the hydrodynamic equations in an expanding FLRW universe. The method is based on a backward differencing scheme for the required stability when solving stiff sets of equations and is designed to be efficient for three-dimensional calculations without sacrificing accuracy. In all, 28 kinetic reactions are solved including both collisional and radiative processes for the following nine separate species: H, H+, He, He+, He++, H-, H2+, H2, and e-. The method identifies those reactions (involving H- and H2+) ocurring on the shortest time scales, decoupling them from the rest of the network and imposing equilibrium concentrations to good accuracy over typical cosmological dynamical times. Several tests of our code are presented, including radiative shock waves, cosmological sheets, conservation constraints, and fully three-dimensional simulations of CDM cosmological evolutions in which we ...

  13. A multi-species collisional operator for full-F gyrokinetics

    Science.gov (United States)

    Estève, D.; Garbet, X.; Sarazin, Y.; Grandgirard, V.; Cartier-Michaud, T.; Dif-Pradalier, G.; Ghendrih, P.; Latu, G.; Norscini, C.

    2015-12-01

    A linearized multi-species collision operator has been developed for an efficient implementation in gyrokinetic codes. This operator satisfies the main expected properties: particle, momentum, and energy conservation, and existence of an H-theorem. A gyrokinetic version is then calculated, which involves derivatives with respect to the gyrocenter position, parallel velocity, and magnetic momentum. An isotropic version in the velocity space can be constructed for the specific problem of trace impurities colliding with a main species. A simpler version that involves derivatives with parallel velocity only has been developed. This reduced version has been implemented in the GYSELA gyrokinetic code, and is shown to comply with particle, momentum, and energy conservation laws. Moreover, the interspecies relaxation rates for momentum and energy agree very well with the theoretical values.

  14. Correlating toxicological effects of ionic liquids on Daphnia magna with in silico calculated linear free energy relationship descriptors.

    Science.gov (United States)

    Cho, Chul-Woong; Yun, Yeoung-Sang

    2016-06-01

    In silico prediction model for toxicological effects of ionic liquids (ILs) is useful to understand ILs' toxicological interactions and to design environmentally benign IL structures. Actually, it is essential since the types of ILs are extremely numerous. Accordingly, prediction models were developed in this study. For the modelling, well-defined linear free energy relationship (LFER) descriptors - i.e. excess molar refraction (E), dipolarity/polarizability (S), H-bonding acidity (A), H-bonding basicity (B), McGowan volume (V), cation interaction (J(+)) and anion interaction (J(-)) - were in silico calculated using density functional theory and conductor-like screening model. These descriptors were then correlated with the toxicological values of ILs to Daphnia magna. First, a model established by Hoover et al. (2007) using measured LFER descriptors of 97 neutral compounds was applied to the prediction of ILs' toxicity. As expected, the model by Hoover et al. (2007) needs to be amended for ILs. To that end, the difference in toxicological interactions between neutral compounds and ILs was addressed by additional single J(+) or five LFER descriptors of cation i.e. Ec, Sc, Bc, Vc, and J(+). Secondly, a prediction model for only ILs was developed by using the three LFER descriptors Ec, Bc, and J(+). The model had a reasonable predictability and robustness of R(2) = 0.880 for the training set, 0.848 for the test set, and 0.867 for the overall set. The established models can be used to design environmentally benign IL structures and to reduce labour, danger, time, and materials compared to the experiment-based study. PMID:26971173

  15. On rotation of multi-species plasmas in toroidal systems

    International Nuclear Information System (INIS)

    This paper describes the poloidal and toroidal spin-up of an isothermal plasma in toroidal equilibria. The mechanism is the Stringer spin-up mechanism which will be generalized to an arbitrary toroidal equilibrium using the Hamada coordinate system. Viscous damping or magnetic pumping balances the accelerating forces and determines the threshold of spin-up. The accelerating forces arise from the Coriolis forces which couple the radial flow to the poloidal flow velocity. The theory presented here is a continuation of a previous paper and applies to a multi-species plasma with impurities. In the two-fluid model - or including impurities - in a multi-fluid model, the flux-friction relations derived on every magnetic surface are the basic equations for computing the poloidal and toroidal flow velocities of the particle species. Futhermore, the effect of turbulent forces on the mean flow is analysed. The Reynolds stresses resulting from anisotropic turbulence provide a force in the tangential direction and thus contribute to the poloidal and toroidal spin-up. Furthermore, turbulence increases the Stringer spin-up mechanism and introduces enhanced plasma losses. The final result is a set of differential equations describing the poloidal and toroidal flow on every magnetic surface. The formalism is valid in every regime of collisionality; however, to obtain specific results, appropriate appoximations must be found for every regime. This will be outlined for the collisional regime where the viscous forces are given by Braginskii's equations. The relation between plasma rotation and the zonal circulation in planetary atmospheres will be discussed. (Author)

  16. Conceptual chemistry approach towards the support effect in supported vanadium oxides : Valence bond calculations on the ionicity of vanadium catalysts

    NARCIS (Netherlands)

    Fievez, Tim; De Proft, Frank; Geerlings, Paul; Weckhuysen, Bert M.; Havenith, Remco W. A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide sup

  17. A simple model for calculating the bulk modulus of the mixed ionic crystal: NH4Cl1−xBr

    Indian Academy of Sciences (India)

    Vassiliki Katsika-Tsigourakou

    2011-10-01

    The ammonium halides are an interesting systems because of their polymorphism and the possible internal rotation of the ammonium ion. The static properties of the mixed ionic crystal NH4Cl1−Br have been recently investigated, using the three-body potential model (TDPM) by applying Vegard’s law. Here, by using a simple theoretical model, we estimate the bulk modulus of the alloys NH4Cl1−Br, in terms of the bulk modulus of the end members alone. The calculated values are comparable to those deduced from the three-body potential model (TDPM) by applying Vegard’s law.

  18. Multi-species monitoring for fugitive gases and CO2 leakage at enhanced oil recovery operations

    Science.gov (United States)

    Risk, D. A.; Lavoie, M.; Brooks, B.; Goeckede, M.; Phillips, C. L.

    2013-12-01

    Carbon, Capture, and Storage (CCS) remains an option for reducing fossil CO2 emissions, but public acceptance continues to limit the roll-out of new projects. Monitoring is one mechanism by which operators can demonstrate credibility, competency, and environmental performance. While many previous research initiatives on surface monitoring have focused largely on soil gas sampling and geochemistries, fewer have tackled site-scale atmospheric detection techniques. This study aims to develop suitable techniques for identifying produced fluid leaks from wells and fugitive emissions from other associated infrastructure, and also to understand the variability of the target gases across land use types, and through time. During the growing season of 2013, we conducted multi-species atmospheric surveys of a 100 square kilometre Enhanced Oil Recovery site, using stationary and vehicle-mounted Cavity Ringdown Spectrometers (CRDS) targeting CH4, δ13C-CH4, CO2, and H2S. The study site offered excellent opportunity to study anthropogenic emissions, as it had well over 1000 active wells onsite, spatially distributed pipeline infrastructure, geochemical differentiation among the various possible emission sources, and also a road network that provided good access to most areas of the site. Leak detection using this method presented challenges related to the atmospheric transport modelling needed to back-calculate the source regions for observed anomalies. Transport models are generally not readily applicable at these smaller scales, so we developed an operational leak detection package. This package included the in situ and roving measurements, interpreted using simple mathematical models, maps, and remote sensing data, to narrow our survey search window and score sub-domains based on the gases present and the probability that these gases were man-made (as opposed to natural), in addition to the likely nature of the anthropogenic source as indicated by gas mixing ratios. Both

  19. Dual-Section DFB-QCLs for Multi-Species Trace Gas Analysis

    Directory of Open Access Journals (Sweden)

    Martin J. Süess

    2016-04-01

    Full Text Available We report on the dynamic behavior of dual-wavelength distributed feedback (DFB quantum cascade lasers (QCLs in continuous wave and intermittent continuous wave operation. We investigate inherent etaloning effects based on spectrally resolved light-current-voltage (LIV characterization and perform time-resolved spectral analysis of thermal chirping during long (>5 µs current pulses. The theoretical aspects of the observed behavior are discussed using a combination of finite element method simulations and transfer matrix method calculations of dual-section DFB structures. Based on these results, we demonstrate how the internal etaloning can be minimized using anti-reflective (AR coatings. Finally, the potential and benefits of these devices for high precision trace gas analysis are demonstrated using a laser absorption spectroscopic setup. Thereby, the atmospherically highly relevant compounds CO2 (including its major isotopologues, CO and N2O are simultaneously determined with a precision of 0.16 ppm, 0.22 ppb and 0.26 ppb, respectively, using a 1-s integration time and an optical path-length of 36 m. This creates exciting new opportunities in the development of compact, multi-species trace gas analyzers.

  20. Closure relations for the multi-species Euler system. Construction and study of relaxation schemes for the multi-species and multi-components Euler systems

    International Nuclear Information System (INIS)

    After having recalled the formal convergence of the semi-classical multi-species Boltzmann equations toward the multi-species Euler system (i.e. mixture of gases having the same velocity), we generalize to this system the closure relations proposed by B. Despres and by F. Lagoutiere for the multi-components Euler system (i.e. mixture of non miscible fluids having the same velocity). Then, we extend the energy relaxation schemes proposed by F. Coquel and by B. Perthame for the numerical resolution of the mono-species Euler system to the multi-species isothermal Euler system and to the multi-components isobar-isothermal Euler system. This allows to obtain a class of entropic schemes under a CFL criteria. In the multi-components case, this class of entropic schemes is perhaps a way for the treatment of interface problems and, then, for the treatment of the numerical mixture area by using a Lagrange + projection scheme. Nevertheless, we have to find a good projection stage in the multi-components case. At last, in the last chapter, we discuss, through the study of a dynamical system, about a system proposed by R. Abgrall and by R. Saurel for the numerical resolution of the multi-components Euler system

  1. To eat and not be eaten: modelling resources and safety in multi-species animal groups.

    Directory of Open Access Journals (Sweden)

    Umesh Srinivasan

    Full Text Available Using mixed-species bird flocks as an example, we model the payoffs for two types of species from participating in multi-species animal groups. Salliers feed on mobile prey, are good sentinels and do not affect prey capture rates of gleaners; gleaners feed on prey on substrates and can enhance the prey capture rate of salliers by flushing prey, but are poor sentinels. These functional types are known from various animal taxa that form multi-species associations. We model costs and benefits of joining groups for a wide range of group compositions under varying abundances of two types of prey-prey on substrates and mobile prey. Our model predicts that gleaners and salliers show a conflict of interest in multi-species groups, because gleaners benefit from increasing numbers of salliers in the group, whereas salliers benefit from increasing gleaner numbers. The model also predicts that the limits to size and variability in composition of multi-species groups are driven by the relative abundance of different types of prey, independent of predation pressure. Our model emphasises resources as a primary driver of temporal and spatial group dynamics, rather than reproductive activity or predation per se, which have hitherto been thought to explain patterns of multi-species group formation and cohesion. The qualitative predictions of the model are supported by empirical patterns from both terrestrial and marine multi-species groups, suggesting that similar mechanisms might underlie group dynamics in a range of taxa. The model also makes novel predictions about group dynamics that can be tested using variation across space and time.

  2. Sushi or fish fingers? Seafood diversity, collapsing fish stocks, and multi-species fishery management

    OpenAIRE

    Quaas, Martin F.; Requate, Till

    2012-01-01

    We present a model of a multi-species fishery and show that (i) consumer preferences for seafood diversity may trigger a sequential collapse of fish stocks under open-access fishery, (ii) the stronger the preferences are for diversity the higher is the need for coordinated multi-species regulation, (iii) second-best optimal management of only one (or a few) species is less strict than socially optimal management of the same species. Finally, (iv) myopic regulation of one species, ignoring spi...

  3. Calculating Hyperfine Couplings in Large Ionic Crystals Containing Hundreds of QM Atoms: Subsystem DFT is the Key

    CERN Document Server

    Kevorkyants, Ruslan; Close, David M; Pavanello, Michele

    2013-01-01

    We present an application of the linear scaling Frozen Density Embedding (FDE) formulation of subsystem DFT to the calculation of isotropic hyperfine coupling constants (hfccs) of atoms belonging to a guanine radical cation embedded in a guanine hydrochloride monohydrate crystal. The model systems considered range from an isolated guanine to a 15,000 atom QM/MM cluster where the QM region is comprised of 36 protonated guanine cations, 36 chlorine anions and 42 water molecules. Our calculations show that the embedding effects of the surrounding crystal cannot be reproduced neither by small model systems nor by a pure QM/MM procedure. Instead, a large QM region is needed to fully capture the complicated nature of the embedding effects in this system. The unprecedented system size for a relativistic all-electron isotropic hfccs calculation can be approached in this work because the local nature of the electronic structure of the organic crystals considered is fully captured by the FDE approach.

  4. Computing multi-species chemical equilibrium with an algorithm based on the reaction extents

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.;

    2013-01-01

    A mathematical model for the solution of a set of chemical equilibrium equations in a multi-species and multiphase chemical system is described. The computer-aid solution of model is achieved by means of a Newton-Raphson method enhanced with a line-search scheme, which deals with the non-negative...

  5. Jointness through fishing days input in a multi-species fishery

    DEFF Research Database (Denmark)

    Hansen, Lars Gårn; Jensen, Carsten Lynge

    forms (e.g. translog, normalized quadratic). In this paper we argue that jointness in the latter, essentially separable fishery is caused by allocation of fishing days input among harvested species. We developed a structural model of a multi-species fishery where the allocation of fishing days input...

  6. Analysis of multi-species point patterns using multivariate log Gaussian Cox processes

    DEFF Research Database (Denmark)

    Waagepetersen, Rasmus; Guan, Yongtao; Jalilian, Abdollah; Mateu, Jorge

    Multivariate log Gaussian Cox processes are flexible models for multivariate point patterns. However, they have so far only been applied in bivariate cases. In this paper we move beyond the bivariate case in order to model multi-species point patterns of tree locations. In particular we address t...

  7. 77 FR 60457 - Draft Midwest Wind Energy Multi-Species Habitat Conservation Plan Within Eight-State Planning...

    Science.gov (United States)

    2012-10-03

    ... Fish and Wildlife Service Draft Midwest Wind Energy Multi-Species Habitat Conservation Plan Within... period for receipt of comments pertaining to the development of the Midwest Wind Energy Multi-Species.... SUPPLEMENTARY INFORMATION: On August 30, 2012 (77 FR 52754), we, the U.S. Fish and Wildlife Service...

  8. 77 FR 52754 - Draft Midwest Wind Energy Multi-Species Habitat Conservation Plan Within Eight-State Planning Area

    Science.gov (United States)

    2012-08-30

    ... Fish and Wildlife Service Draft Midwest Wind Energy Multi-Species Habitat Conservation Plan Within..., The Conservation Fund would develop a regional framework of conservation lands to be used as a... coordination with our planning partners, intend to prepare the Midwest Wind Energy Multi-Species...

  9. Hydroxyl-functionalized 1-(2-hydroxyethyl)-3-methyl imidazolium ionic liquids: thermodynamic and structural properties using molecular dynamics simulations and ab initio calculations.

    Science.gov (United States)

    Fakhraee, Mostafa; Zandkarimi, Borna; Salari, Hadi; Gholami, Mohammad Reza

    2014-12-11

    The influences of hydroxyl functional group (-OH) on the thermodynamic and structural properties of ionic liquids (ILs) composed of 1-(2-Hydroxyethyl)-3-methyl imidazolium ([C2OHmim](+)) cation and the six different conventional anions, including [Cl](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) have been extensively investigated using classical molecular dynamics (MD) simulations combined with ab initio calculations over a wide range of temperature (298-550 K). The volumetric thermodynamic properties, enthalpy of vaporization, cohesive energy density, Hildebrand solubility parameter, and heat capacity at constant pressure were estimated at desired temperature. The simulated densities were in good agreement with the experimental data with a slight overestimation. The interionic interaction of selected ILs was also computed using both the MD simulations and ab initio calculations. It was found that the highest association of cation and anion is attributed to [C2OHmim][Cl] followed by [C2OHmim][NO3], and [C2OHmim][Tf2N] with the bulkiest anion has the weakest interionic interaction among chosen ILs. The similar trend of interactions energies was nearly observed from cohesive energy density results. Additional structural details were comprehensively yielded by calculating radial distribution functions (RDFs) and spatial distribution function (SDFs) at 358 K. The most stable configurations of isolated and dimer ion pairs of these ILs were in excellent consistency with RDFs and SDFs results. Significant changes in arrangement of anions around the [C2OHmim](+) cation in comparison with conventional imidazolium-based ILs can be inferred from the MD simulations and ab initio results. Also, microscopic structural properties disclosed that the most strong cation-cation interaction is ascribed to the hydroxyl-functionalized ILs composed of bulkier anions, whereas ILs incorporating [Cl](-) and [NO3](-) anions are mainly involved in cation-anion interactions. The

  10. In Silico Calculation of Infinite Dilution Activity Coefficients of Molecular Solutes in Ionic Liquids: Critical Review of Current Methods and New Models Based on Three Machine Learning Algorithms.

    Science.gov (United States)

    Paduszyński, Kamil

    2016-08-22

    The aim of the paper is to address all the disadvantages of currently available models for calculating infinite dilution activity coefficients (γ(∞)) of molecular solutes in ionic liquids (ILs)-a relevant property from the point of view of many applications of ILs, particularly in separations. Three new models are proposed, each of them based on distinct machine learning algorithm: stepwise multiple linear regression (SWMLR), feed-forward artificial neural network (FFANN), and least-squares support vector machine (LSSVM). The models were established based on the most comprehensive γ(∞) data bank reported so far (>34 000 data points for 188 ILs and 128 solutes). Following the paper published previously [J. Chem. Inf. Model 2014, 54, 1311-1324], the ILs were treated in terms of group contributions, whereas the Abraham solvation parameters were used to quantify an impact of solute structure. Temperature is also included in the input data of the models so that they can be utilized to obtain temperature-dependent data and thus related thermodynamic functions. Both internal and external validation techniques were applied to assess the statistical significance and explanatory power of the final correlations. A comparative study of the overall performance of the investigated SWMLR/FFANN/LSSVM approaches is presented in terms of root-mean-square error and average absolute relative deviation between calculated and experimental γ(∞), evaluated for different families of ILs and solutes, as well as between calculated and experimental infinite dilution selectivity for separation problems benzene from n-hexane and thiophene from n-heptane. LSSVM is shown to be a method with the lowest values of both training and generalization errors. It is finally demonstrated that the established models exhibit an improved accuracy compared to the state-of-the-art model, namely, temperature-dependent group contribution linear solvation energy relationship, published in 2011 [J. Chem

  11. Confinement effects for ionic carriers in SrTiO3 ultrathin films: first-principles calculations of oxygen vacancies.

    Science.gov (United States)

    Kotomin, E A; Alexandrov, V; Gryaznov, D; Evarestov, R A; Maier, J

    2011-01-21

    One-dimensional confinement effects are modelled within the hybrid HF-DFT LCAO approach considering neutral and single-charged oxygen vacancies in SrTiO(3) ultrathin films. The calculations reveal that confinement effects are surprisingly short-range in this partly covalent perovskite; already for film thickness of 2-3 nm (and we believe, similar size nanoparticles) only the surface-plane defect properties differ from those in the bulk. This includes a pronounced decrease of the defect formation energy (by ∼1 eV), a much deeper defect band level and a noticeable change in the electronic density redistribution at the near-surface vacancy site with respect to that in the bulk. The results also show that the size effect pertains to the interactions between the oxygen vacancy and two neighboring titanium atoms and orientation (parallel or perpendicular to the surface) of the Ti-V(O)-Ti complex. In particular, we predict considerable oxygen vacancy segregation towards the surface. PMID:21116562

  12. Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force

    Science.gov (United States)

    Antunes, A.; Glover, P. M.; Li, Y.; Mian, O. S.; Day, B. L.

    2012-07-01

    Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.

  13. Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force

    International Nuclear Information System (INIS)

    Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635–40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier–Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier–Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced

  14. Multi-species, two-velocity, one-space Fokker-Planck code

    International Nuclear Information System (INIS)

    Discussion of a new Fokker-Planck code is presented. The code performs a kinetic simulation in two velocity coordinates and one space coordinate (aligned along the magnetic field) of a multi-species plasma using a Rosenbluth potential formulation to handle the collision term, and is being used to examine various plasma conditions where the standard fluid approximations are invalid. Some results comparing the collisionless and collisional sheath are presented

  15. Unification of multi-species vertebrate anatomy ontologies for comparative biology in Uberon

    OpenAIRE

    Haendel M.A.; Balhoff J.P.; Bastian F.B.; Blackburn D.C.; Blake J.A.; Bradford Y.; Comte A.; Dahdul W.M.; Dececchi T.A.; Druzinsky R.E.; Hayamizu T.F.; Ibrahim N.; Lewis S.E.; Mabee P.M.; Niknejad A.

    2014-01-01

    BACKGROUND: Elucidating disease and developmental dysfunction requires understanding variation in phenotype. Single-species model organism anatomy ontologies (ssAOs) have been established to represent this variation. Multi-species anatomy ontologies (msAOs; vertebrate skeletal, vertebrate homologous, teleost, amphibian AOs) have been developed to represent 'natural' phenotypic variation across species. Our aim has been to integrate ssAOs and msAOs for various purposes, including establishing ...

  16. Disturbance Frequency Determines Morphology and Community Development in Multi-Species Biofilm at the Landscape Scale

    OpenAIRE

    Milferstedt, Kim; Santa-Catalina, Gaelle; Godon, Jean-Jacques; Escudié, Renaud; Bernet, Nicolas

    2013-01-01

    Many natural and engineered biofilm systems periodically face disturbances. Here we present how the recovery time of a biofilm between disturbances (expressed as disturbance frequency) shapes the development of morphology and community structure in a multi-species biofilm at the landscape scale. It was hypothesized that a high disturbance frequency favors the development of a stable adapted biofilm system while a low disturbance frequency promotes a dynamic biofilm response. Biofilms were gro...

  17. A Numerical Comparison of Ionic Multi-Species Diffusion with and without Sorption Hysteresis for Cement-Based Materials

    DEFF Research Database (Denmark)

    Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica

    2015-01-01

    sorption hysteresis model. The examples illustrate the impact of changing relative humidity at the mass transport boundary on the adsorption and desorption stages of a cement-based material. Changes in the pore solution ion concentrations are a result of the changing moisture content, which are shown by......A finite element solution for a mass transport model for porous materials accounting for sorption hysteresis is presented in this paper. The model is prepared for modeling of concrete durability, but the general presentation makes it suitable for other porous materials like soil and tissues. The...... the example. Comparing the two approaches showed significant deviations in the liquid content and ion concentrations, in parts of the domain considered....

  18. Learning Ionic

    CERN Document Server

    Ravulavaru, Arvind

    2015-01-01

    This book is intended for those who want to learn how to build hybrid mobile applications using Ionic. It is also ideal for people who want to explore theming for Ionic apps. Prior knowledge of AngularJS is essential to complete this book successfully.

  19. First record of multi-species synchronous coral spawning from Malaysia

    Directory of Open Access Journals (Sweden)

    Alvin Chelliah

    2015-02-01

    Full Text Available Knowledge about the timing and synchrony of coral spawning has important implications for both the ecology and management of coral reef ecosystems. Data on the timing of spawning and extent of synchrony, however, are still lacking for many coral reefs, particularly from equatorial regions and from locations within the coral triangle. Here we present the first documentation of a multi-species coral spawning event from reefs around Pulau Tioman, Peninsular Malaysia, a popular diving and tourist destination located on the edge of the coral triangle. At least 8 coral species from 3 genera (Acropora, Montipora and Porites participated in multi-species spawning over five nights in April 2014, between two nights before and two nights after the full moon. In addition, two Acropora species were witnessed spawning one night prior to the full moon in October 2014. While two of the Acropora species that reproduced in April (A. millepora and A. nasuta exhibited highly synchronous spawning (100% of sampled colonies, two other common species (A. hyacinthus and A. digitifera did not contain visible eggs in the majority of colonies sampled (i.e., <15% of colonies in either April or October, suggesting that these species spawn at other times of the year. To the best of our knowledge, this is the first detailed documented observation of multi-species coral spawning from reefs in Malaysia. These data provide further support for the contention that this phenomenon is a feature of all speciose coral assemblages, including equatorial reefs. More research is needed, however, to determine the seasonal cycles and extent of spawning synchrony on these reefs and elsewhere in Malaysia.

  20. The antimicrobial effects of Citrus limonum and Citrus aurantium essential oils on multi-species biofilms

    Directory of Open Access Journals (Sweden)

    Sarah Almeida Coelho Oliveira

    2014-01-01

    Full Text Available The aim of this study was to evaluate the effects of Citrus limonum and Citrus aurantium essential oils (EOs compared to 0.2% chlorhexidine (CHX and 1% sodium hypochlorite (NaOCl on multi-species biofilms formed by Candida albicans, Enterococcus faecalis and Escherichia coli. The biofilms were grown in acrylic disks immersed in broth, inoculated with microbial suspension (106 cells/mL and incubated at 37°C / 48 h. After the biofilms were formed, they were exposed for 5 minutes to the solutions (n = 10: C. aurantium EO, C. limonum EO, 0.2% CHX, 1% NaOCl or sterile saline solution [0.9% sodium chloride (NaCl]. Next, the discs were placed in sterile 0.9% NaCl and sonicated to disperse the biofilms. Tenfold serial dilutions were performed and the aliquots were seeded onto selective agar and incubated at 37°C / 48 h. Next, the number of colony-forming units per milliliter was counted and analyzed statistically (Tukey test, p ≤ 0.05. C. aurantium EO and NaOCl inhibited the growth of all microorganisms in multi-species biofilms. C. limonum EO promoted a 100% reduction of C. albicans and E. coli, and 49.3% of E. faecalis. CHX was less effective against C. albicans and E. coli, yielding a reduction of 68.8% and 86.7%, respectively. However, the reduction of E. faecalis using CHX (81.7% was greater than that obtained using C. limonum EO. Both Citrus limonum and Citrus aurantium EOs are effective in controlling multi-species biofilms; the microbial reductions achieved by EOs were not only similar to those of NaOCl, but even higher than those achieved by CHX, in some cases.

  1. Dynamic model for the joint scalar probability in multi-species turbulent mixing

    Science.gov (United States)

    Ristorcelli, J. R.; Bakosi, J.

    2010-11-01

    We present a probability density function (PDF) model for multi-species scalar mixing in turbulent flows. In the proposed model the scalars are governed by a system of stochastic differential equations, discretized and integrated in a Monte-Carlo fashion. The model is local in composition space, accounts for different scalar mixing rates and Schmidt numbers and can represent a variety of PDF shapes, including a multiple-delta in the unmixed and a joint (bounded) Gaussian in the fully mixed states. The method is intended for passive, active or reactive scalars in shear-driven and/or variable-density pressure-gradient-driven turbulence.

  2. NTERACTION BETWEEN SURFACE CHARGE PHENOMENA AND MULTI-SPECIES DIFFUSION IN CEMENT BASED MATERIALS

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2008-01-01

    Measurements strongly indicate that the ‘inner’ surface of the microscopic structure of cement based materials has a fixed negative charge. This charge contributes to the formation of so-called electrical double layers. In the case of cement based materials the ionic species located in such layers...... diffusion of different ionic species in the pore system of cement based materials....

  3. Entropy and Ionic Conductivity

    OpenAIRE

    Zhang, Yong-Jun

    2012-01-01

    It is known that the ionic conductivity can be obtained by using the diffusion constant and the Einstein relation. We derive it here by extracting it from the steady electric current which we calculate in three ways, using statistics analysis, an entropy method, and an entropy production approach.

  4. Modeling of the ionic transfers in saturated porous media: application to the penetration of chlorides through cementing materials

    International Nuclear Information System (INIS)

    In this work, the problem of ionic species transport through concrete porous media has been documented. Chloride ions penetration in cementitious materials is one of the processes widely responsible for the degradation of concrete structures. Therefore there exists an immense need for its correct understanding and quantification. Different research groups worldwide have proposed different chloride ingress models. Here, a one-dimensional model based on a multi-species approach of the ionic transport is presented. It is the new version of a previous model MsDiff developed a few years ago in our group that describes the diffusion of ionic species with the Nernst-Planck equation instead of Fick's laws. This newer version is named, the package version of MsDiff after it requires a package of five input data at any given age of concrete. With a multi-species approach, it is possible to take into account the interactions, which exist among different ionic species in pore solution of concrete. The numerical scheme of the model is based on finite difference method with Crank-Nickolson and Law-Wendroff techniques. In order to run MsDiff, we do need an input data. Several experiments were performed accordingly to provide experimental feedback to MsDiff. Standard immersion tests were conducted to validate the outcomes of MsDiff. Special attention is given to the diffusion coefficients of the ions and the interactions between the ionic species and the solid phase. In addition to MsDiff, some other existing models were also tried for the sake of comparison with the experimental chloride profiles. Certain experimentation was conducted to watch the effect of exposure period, concrete age at exposure and concentration in the environmental solution. In the end, the simulations were performed with MsDiff in order to calculate the chloride-induced corrosion initiation time using the experimental data already achieved while making use of different criteria adopted by different research

  5. Ecotoxicity of the veterinary pharmaceutical ivermectin tested in a soil multi-species (SMS) system

    International Nuclear Information System (INIS)

    The present study tests the effect of antiparasitic compound ivermectin in a constructed food-web system, a soil multi-species (SMS) higher tier test system. Mutualism, competition and predation within the SMS system were introduced by the addition of five collembolan species, one enchytraeid and a predatory mite species. Bait lamina sticks were incorporated as a measure of functional toxicity, attempting to the integrated feeding activity of the invertebrates. The study showed that on the community level all treatments were significantly affecting the community abundance and composition and that the decrease in abundance corresponded well with increasing exposure concentration for all species. Since all concentrations had significant adverse effect on the community structure, the community-based no-effect-concentration is below the lowest test concentration of 0.25 mg kg−1, whereas the EC10 for the individual species were as low as 0.05 mg kg−1. The bait lamina respond was only affected at the highest exposure concentration. - Highlights: ► A multi-species test system was used to evaluate the impact of hazardous substances. ► The pharmaceutical ivermectin was toxic to a wide set of soil invertebrates. ► The toxicity to springtails was higher when exposed in co-existence with a predator. ► Structural endpoints were more sensitive than functional ditto measured by Bait lamina. - Hazardous substances are shown more toxic to soil dwelling invertebrates when exposed in co-existence with other species including a predator.

  6. Comparative microbial modules resource: generation and visualization of multi-species biclusters.

    Directory of Open Access Journals (Sweden)

    Thadeous Kacmarczyk

    2011-12-01

    Full Text Available The increasing abundance of large-scale, high-throughput datasets for many closely related organisms provides opportunities for comparative analysis via the simultaneous biclustering of datasets from multiple species. These analyses require a reformulation of how to organize multi-species datasets and visualize comparative genomics data analyses results. Recently, we developed a method, multi-species cMonkey, which integrates heterogeneous high-throughput datatypes from multiple species to identify conserved regulatory modules. Here we present an integrated data visualization system, built upon the Gaggle, enabling exploration of our method's results (available at http://meatwad.bio.nyu.edu/cmmr.html. The system can also be used to explore other comparative genomics datasets and outputs from other data analysis procedures - results from other multiple-species clustering programs or from independent clustering of different single-species datasets. We provide an example use of our system for two bacteria, Escherichia coli and Salmonella Typhimurium. We illustrate the use of our system by exploring conserved biclusters involved in nitrogen metabolism, uncovering a putative function for yjjI, a currently uncharacterized gene that we predict to be involved in nitrogen assimilation.

  7. Species composition of a soil invertebrate multi-species test system determines the level of ecotoxicity

    International Nuclear Information System (INIS)

    A soil multi-species, SMS, experimental test system consisting of the natural microbial community, five collembolan species and a predatory mite along with either Enchytraeus crypticus or the earthworm Eisenia fetida were exposed to α-cypermethrin. A comparison of the performance of these two types of SMSs is given to aid the development of a standard test system. E. fetida had a positive effect on the majority of the species, reducing the negative insecticide effect. E. fetida affected the species sensitivity and decreased the degradation of the insecticide due to the organic matter incorporation of earthworm food. After 8 weeks, the EC50 was 0.76 mg kg−1 for enchytraeids and ranged between 2.7 and 18.9 mg kg−1 for collembolans, more sensitive than previously observed with single species. Changes observed in the community structure and function illustrates the strength of a multi-species test system as an ecotoxicological tool compared to single species tests. -- Highlights: • Degradation of alpha-cypermethrin was faster with enchytraeids than with earthworms. • Lumbricid castings and bioturbation explains bioavailability of α-cypermethrin. • Pesticide effects on soil arthropods alter with the community composition. • Multispecies test systems are feasible with either an enchytraeid or a lumbricid. • Collembolans are more sensitive to cypermethrin with enchytraeids than with earthworms. -- Soil ecotoxicological fate and effects in multispecies test systems are affected by earthworm activity

  8. Modified Thomson spectrometer design for high energy, multi-species ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Gwynne, D.; Kar, S., E-mail: s.kar@qub.ac.uk; Doria, D.; Ahmed, H.; Hanton, F. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Cerchez, M.; Swantusch, M.; Willi, O. [Institut für Laser-und Plasmaphysik, Heinrich-Heine-Universität, Düsseldorf (Germany); Fernandez, J. [Instituto de Fusión Nuclear UPM, Jose Gutierrez Abascal 2, E28006 Madrid (Spain); Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Gray, R. J.; MacLellan, D. A.; McKenna, P. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Green, J. S.; Neely, D. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Najmudin, Z.; Streeter, M. [Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom); Ruiz, J. A. [Instituto de Fusión Nuclear UPM, Jose Gutierrez Abascal 2, E28006 Madrid (Spain); Schiavi, A. [Dipartimento SBAI, Università di Roma “La Sapienza,” 00161 Rome (Italy); Zepf, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Helmholtz Institut Jena, D-07743 Jena (Germany); Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Institute of Physics of the ASCR, ELI-Beamlines Project, Na Slovance 2, 18221 Prague (Czech Republic)

    2014-03-15

    A modification to the standard Thomson parabola spectrometer is discussed, which is designed to measure high energy (tens of MeV/nucleon), broad bandwidth spectra of multi-species ions accelerated by intense laser plasma interactions. It is proposed to implement a pair of extended, trapezoidal shaped electric plates, which will not only resolve ion traces at high energies, but will also retain the lower energy part of the spectrum. While a longer (along the axis of the undeflected ion beam direction) electric plate design provides effective charge state separation at the high energy end of the spectrum, the proposed new trapezoidal shape will enable the low energy ions to reach the detector, which would have been clipped or blocked by simply extending the rectangular plates to enhance the electrostatic deflection.

  9. Evolution of laser induced electromagnetic postsolitons in multi-species plasma

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yue, E-mail: yue.liu@eli-beams.eu; Gu, Yanjun; Weber, Stefan; Korn, Georg [Institute of Physics of the ASCR, ELI-Beamlines Project, Na Slovance 2, Prague 18221 (Czech Republic); Klimo, Ondřej [Institute of Physics of the ASCR, ELI-Beamlines Project, Na Slovance 2, Prague 18221 (Czech Republic); FNSPE, Czech Technical University in Prague, Prague 11519 (Czech Republic); Esirkepov, Timur Zh.; Bulanov, Sergei V. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan)

    2015-11-15

    The evolution of an s-polarized relativistic electromagnetic soliton created in multi-species plasma by an intense short laser pulse is investigated using two-dimensional particle-in-cell simulations. The multi-component plasma consists of electrons and high-Z ions with a small addition of protons. By comparison, the evolution of postsoliton is very different from that in hydrogen plasma. A halo-like structure is found in spatial patterns of both electromagnetic fields and electron densities. The process of energy depletion is much slower due to the smaller charge-to-mass ratio of ions, which implies a better way of detecting postsolitons in simulations and experiments. In addition, it is found that the Coulomb explosion of high-Z ions in the postsoliton stage facilitates low-Z ion acceleration, and the maximum energy of low-Z ions increases with the component ratio of high-Z to low-Z ions.

  10. A multi-species 13-moment model for moderately collisional plasmas

    Science.gov (United States)

    Miller, S. T.; Shumlak, U.

    2016-08-01

    Fluid-based models of collisional transport in multi-species plasmas have typically been applied to parameter regimes where a local thermal equilibrium is assumed. While this parameter regime is valid for low temperature and/or high density applications, it begins to fail as plasmas enter the collisionless regime and kinetic effects dominate the physics. A plasma model is presented that lays the foundation for extending the validity of the collisional fluid regime using an anisotropic 13-moment fluid model derived from the Pearson type-IV probability distribution. The model explicitly evolves the pressure tensor and heat flux vector along with the density and flow velocity to capture dynamics usually restricted to kinetic models. Each particle species is modeled individually and collectively coupled through electromagnetic and collisional interactions.

  11. Asymptotic behaviour of two-point functions in multi-species models

    Directory of Open Access Journals (Sweden)

    Karol K. Kozlowski

    2016-05-01

    Full Text Available We extract the long-distance asymptotic behaviour of two-point correlation functions in massless quantum integrable models containing multi-species excitations. For such a purpose, we extend to these models the method of a large-distance regime re-summation of the form factor expansion of correlation functions. The key feature of our analysis is a technical hypothesis on the large-volume behaviour of the form factors of local operators in such models. We check the validity of this hypothesis on the example of the SU(3-invariant XXX magnet by means of the determinant representations for the form factors of local operators in this model. Our approach confirms the structure of the critical exponents obtained previously for numerous models solvable by the nested Bethe Ansatz.

  12. Subaerial biofilms on granitic historic buildings: microbial diversity and development of phototrophic multi-species cultures.

    Science.gov (United States)

    Vázquez-Nion, D; Rodríguez-Castro, J; López-Rodríguez, M C; Fernández-Silva, I; Prieto, B

    2016-07-01

    Microbial communities of natural subaerial biofilms developed on granitic historic buildings of a World Heritage Site (Santiago de Compostela, NW Spain) were characterized and cultured in liquid BG11 medium. Environmental barcoding through next-generation sequencing (Pacific Biosciences) revealed that the biofilms were mainly composed of species of Chlorophyta (green algae) and Ascomycota (fungi) commonly associated with rock substrata. Richness and diversity were higher for the fungal than for the algal assemblages and fungi showed higher heterogeneity among samples. Cultures derived from natural biofilms showed the establishment of stable microbial communities mainly composed of Chlorophyta and Cyanobacteria. Although most taxa found in these cultures were not common in the original biofilms, they are likely common pioneer colonizers of building stone surfaces, including granite. Stable phototrophic multi-species cultures of known microbial diversity were thus obtained and their reliability to emulate natural colonization on granite should be confirmed in further experiments. PMID:27192622

  13. Competition between aggregation and migration processes of a multi-species system

    Institute of Scientific and Technical Information of China (English)

    Ke Jian-Hong; Zhuang You-Yi; Lin Zhen-Quan; Ye Peng

    2005-01-01

    We propose a solvable multi-species aggregation-migration model, in which irreversible aggregations occur between any two aggregates of the same species and reversible migrations occur between any two different species. The kinetic behaviour of an aggregation-migration system is then studied by means of the mean-field rate equation. The results show that the kinetics of the system depends crucially on the details of reaction events such as initial concentration distributions and ratios of aggregation rates to migration rate. In general, the aggregate mass distribution of each species always obeys a conventional or a generalized scaling law, and for most cases at least one species is scaled according to a conventional form with universal constants. Moreover, there is at least one species that can survive finally.

  14. Evolution of laser induced electromagnetic postsolitons in multi-species plasma

    International Nuclear Information System (INIS)

    The evolution of an s-polarized relativistic electromagnetic soliton created in multi-species plasma by an intense short laser pulse is investigated using two-dimensional particle-in-cell simulations. The multi-component plasma consists of electrons and high-Z ions with a small addition of protons. By comparison, the evolution of postsoliton is very different from that in hydrogen plasma. A halo-like structure is found in spatial patterns of both electromagnetic fields and electron densities. The process of energy depletion is much slower due to the smaller charge-to-mass ratio of ions, which implies a better way of detecting postsolitons in simulations and experiments. In addition, it is found that the Coulomb explosion of high-Z ions in the postsoliton stage facilitates low-Z ion acceleration, and the maximum energy of low-Z ions increases with the component ratio of high-Z to low-Z ions

  15. Asymptotic behaviour of two-point functions in multi-species models

    Science.gov (United States)

    Kozlowski, Karol K.; Ragoucy, Eric

    2016-05-01

    We extract the long-distance asymptotic behaviour of two-point correlation functions in massless quantum integrable models containing multi-species excitations. For such a purpose, we extend to these models the method of a large-distance regime re-summation of the form factor expansion of correlation functions. The key feature of our analysis is a technical hypothesis on the large-volume behaviour of the form factors of local operators in such models. We check the validity of this hypothesis on the example of the SU (3)-invariant XXX magnet by means of the determinant representations for the form factors of local operators in this model. Our approach confirms the structure of the critical exponents obtained previously for numerous models solvable by the nested Bethe Ansatz.

  16. Crystal Structure, Vibrational Spectroscopy and ab Initio Density Functional Theory Calculations on the Ionic Liquid forming 1,1,3,3-Tetramethylguanidinium bis{(trifluoromethyl)sulfonyl}amide

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Riisager, Anders; Nguyen van Buu, Olivier;

    2009-01-01

    The salt 1,1,3,3-tetramethylguanidinium bis{(trifluoromethyl)sulfonyl}amide, [((CH3)(2)N)(2)C=NH2](+)[N(SO2-CF3)(2)](-) or [tmgH][NTf2], easily forms an ionic liquid with high SO2 absorbing capacity. The crystal structure of the salt was determined at 120(2) K by X-ray diffraction. The structure...

  17. Spatial, temporal, and environmental dynamics of a multi-species epinephelid spawning aggregation in Pohnpei, Micronesia

    Science.gov (United States)

    Rhodes, K. L.; Nemeth, R. S.; Kadison, E.; Joseph, E.

    2014-09-01

    Long-term and short-term underwater visual censuses using SCUBA, technical Nitrox, and closed circuit rebreathers (CCR) were carried out in Pohnpei, Micronesia, to define spatial and temporal dynamics within a semi-protected multi-species epinephelid (fish) spawning aggregation (FSA) of brown-marbled grouper, Epinephelus fuscoguttatus, camouflage grouper, Epinephelus polyphekadion, and squaretail coralgrouper, Plectropomus areolatus. Results identified species-specific patterns of habitat use, abundance, residency, and dispersal of FSAs. Fish spawning aggregations formed and dispersed monthly within a 21-160-d period after winter solstice within adjacent yet distinct outer reef habitats. The reproductive season coincided with periods of seasonally low sub-surface seawater temperature. Peaks in density varied among species both within the calendar year and relative to the winter solstice. Significant long-term declines in FSA density were observed for all three species, suggesting population-level fishery-induced impacts, similar to those previously reported for E. polyphekadion. Differences in density estimates were also observed between dive gear, with a threefold difference in densities measured by CCR for E. polyphekadion versus SCUBA that suggest a disturbance effect from exhaled SCUBA bubbles for this species. CCR also allowed surveys to be conducted over a larger area in a single dive, thereby improving the potential to gauge actual abundance and density within FSAs. Based on these findings, a combination of long-term and intensive short-term monitoring strategies is recommended to fully characterize trends in seasonal abundance and habitat use for aggregating species at single or multi-species FSA sites. Inherent variations in the timing and distribution of species within FSA make fine-scale temporal management protocols less effective than blanket protective coverage of these species at (e.g., marine protected areas covering FSAs and adjacent migratory

  18. Antimicrobial nisin acts against saliva derived multi-species biofilms without cytotoxicity to human oral cells

    Science.gov (United States)

    Shin, Jae M.; Ateia, Islam; Paulus, Jefrey R.; Liu, Hongrui; Fenno, J. Christopher; Rickard, Alexander H.; Kapila, Yvonne L.

    2015-01-01

    Objectives: Nisin is a lantibiotic widely used for the preservation of food and beverages. Recently, investigators have reported that nisin may have clinical applications for treating bacterial infections. The aim of this study was to investigate the effects of ultra pure food grade Nisin ZP (>95% purity) on taxonomically diverse bacteria common to the human oral cavity and saliva derived multi-species oral biofilms, and to discern the toxicity of nisin against human cells relevant to the oral cavity. Methods: The minimum inhibitory concentrations and minimum bactericidal concentrations of taxonomically distinct oral bacteria were determined using agar and broth dilution methods. To assess the effects of nisin on biofilms, two model systems were utilized: a static and a controlled flow microfluidic system. Biofilms were inoculated with pooled human saliva and fed filter-sterilized saliva for 20–22 h at 37°C. Nisin effects on cellular apoptosis and proliferation were evaluated using acridine orange/ethidium bromide fluorescent nuclear staining and lactate dehydrogenase activity assays. Results: Nisin inhibited planktonic growth of oral bacteria at low concentrations (2.5–50 μg/ml). Nisin also retarded development of multi-species biofilms at concentrations ≥1 μg/ml. Specifically, under biofilm model conditions, nisin interfered with biofilm development and reduced biofilm biomass and thickness in a dose-dependent manner. The treatment of pre-formed biofilms with nisin resulted in dose- and time-dependent disruption of the biofilm architecture along with decreased bacterial viability. Human cells relevant to the oral cavity were unaffected by the treatment of nisin at anti-biofilm concentrations and showed no signs of apoptotic changes unless treated with much higher concentrations (>200 μg/ml). Conclusion: This work highlights the potential therapeutic value of high purity food grade nisin to inhibit the growth of oral bacteria and the development of

  19. The antimicrobial effects of Citrus limonum and Citrus aurantium essential oils on multi-species biofilms.

    Science.gov (United States)

    Oliveira, Sarah Almeida Coelho; Zambrana, Jéssica Rabelo Mina; Iorio, Fernanda Bispo Reis Di; Pereira, Cristiane Aparecida; Jorge, Antonio Olavo Cardoso

    2014-01-01

    The aim of this study was to evaluate the effects of Citrus limonum and Citrus aurantium essential oils (EOs) compared to 0.2% chlorhexidine (CHX) and 1% sodium hypochlorite (NaOCl) on multispecies biofilms formed by Candida albicans, Enterococcus faecalis and Escherichia coli. The biofilms were grown in acrylic disks immersed in broth, inoculated with microbial suspension (106 cells/mL) and incubated at 37°C / 48 h. After the biofilms were formed, they were exposed for 5 minutes to the solutions (n = 10): C. aurantium EO, C. limonum EO, 0.2% CHX, 1% NaOCl or sterile saline solution [0.9% sodium chloride NaCl)]. Next, the discs were placed in sterile 0.9% NaCl and sonicated to disperse the biofilms. Tenfold serial dilutions were performed and the aliquots were seeded onto selective agar and incubated at 37°C / 48 h. , the number of colony-forming units per milliliter was counted and analyzed statistically (Tukey test, p ≤ 0.05). C. aurantium EO and NaOCl inhibited the growth of all microorganisms in multi-species biofilms. C. limonum EO promoted a 100% reduction of C. albicans and E. coli, 49.3% of E. faecalis. CHX was less effective against C. albicans and E. coli, yielding a reduction of 68.8% and 86.7%, respectively. However, the reduction of E. faecalis using CHX (81.7%) was greater than that obtained using C. limonum EO. Both Citrus limonum and Citrus aurantium EOs are effective in controlling multi-species biofilms; the microbial reductions achieved by EOs were not only similar to those of NaOCl, but even higher than those achieved by CHX, in some cases. PMID:25000605

  20. Effect of Antimicrobial Denture Base Resin on Multi-Species Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Keke Zhang

    2016-06-01

    Full Text Available Our aims of the research were to study the antimicrobial effect of dimethylaminododecyl methacrylate (DMADDM modified denture base resin on multi-species biofilms and the biocompatibility of this modified dental material. Candida albicans (C. albicans, Streptococcus mutans (S. mutans, Streptococcus sanguinis (S. sanguinis, as well as Actinomyces naeslundii (A. naeslundii were used for biofilm formation on denture base resin. Colony forming unit (CFU counts, microbial viability staining, and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl-2H-tetrazolium-5-carboxanilide (XTT array were used to evaluate the antimicrobial effect of DMADDM. C. albicans staining and Real-time PCR were used to analyze the morphology and expression of virulence genes of C. albicans in biofilm. Lactate dehydrogenase (LDH array and Real-time PCR were conducted to examine the results after biofilm co-cultured with epithelial cell. Hematoxylin and eosin (HE staining followed by histological evaluation were used to study the biocompatibility of this modified material. We found that DMADDM containing groups reduced both biomass and metabolic activity of the biofilm significantly. DMADDM can also inhibit the virulence of C. albicans by means of inhibiting the hyphal development and downregulation of two virulence related genes. DMADDM significantly reduced the cell damage caused by multi-species biofilm according to the LDH activity and reduced the expression of IL-18 gene of the cells simultaneously. The in vivo histological evaluation proved that the addition of DMADDM less than 6.6% in denture material did not increase the inflammatory response (p > 0.05. Therefore, we proposed that the novel denture base resin containing DMADDM may be considered as a new promising therapeutic system against problems caused by microbes on denture base such as denture stomatitis.

  1. Effect of Antimicrobial Denture Base Resin on Multi-Species Biofilm Formation.

    Science.gov (United States)

    Zhang, Keke; Ren, Biao; Zhou, Xuedong; Xu, Hockin H K; Chen, Yu; Han, Qi; Li, Bolei; Weir, Michael D; Li, Mingyun; Feng, Mingye; Cheng, Lei

    2016-01-01

    Our aims of the research were to study the antimicrobial effect of dimethylaminododecyl methacrylate (DMADDM) modified denture base resin on multi-species biofilms and the biocompatibility of this modified dental material. Candida albicans (C. albicans), Streptococcus mutans (S. mutans), Streptococcus sanguinis (S. sanguinis), as well as Actinomyces naeslundii (A. naeslundii) were used for biofilm formation on denture base resin. Colony forming unit (CFU) counts, microbial viability staining, and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) array were used to evaluate the antimicrobial effect of DMADDM. C. albicans staining and Real-time PCR were used to analyze the morphology and expression of virulence genes of C. albicans in biofilm. Lactate dehydrogenase (LDH) array and Real-time PCR were conducted to examine the results after biofilm co-cultured with epithelial cell. Hematoxylin and eosin (HE) staining followed by histological evaluation were used to study the biocompatibility of this modified material. We found that DMADDM containing groups reduced both biomass and metabolic activity of the biofilm significantly. DMADDM can also inhibit the virulence of C. albicans by means of inhibiting the hyphal development and downregulation of two virulence related genes. DMADDM significantly reduced the cell damage caused by multi-species biofilm according to the LDH activity and reduced the expression of IL-18 gene of the cells simultaneously. The in vivo histological evaluation proved that the addition of DMADDM less than 6.6% in denture material did not increase the inflammatory response (p > 0.05). Therefore, we proposed that the novel denture base resin containing DMADDM may be considered as a new promising therapeutic system against problems caused by microbes on denture base such as denture stomatitis. PMID:27367683

  2. Comparison of the Effective Fragment Potential Method with Symmetry-Adapted Perturbation Theory in the Calculation of Intermolecular Energies for Ionic Liquids.

    Science.gov (United States)

    Tan, Samuel Y S; Izgorodina, Ekaterina I

    2016-06-14

    The effective fragment potential (EFP) method that decomposes the interaction energy as a sum of the five fundamental forces-electrostatic, exchange-repulsion, polarization, dispersion, and charge transfer-was applied to a large test set of ionic liquid ion pairs and compared against the state-of-the-art method, Symmetry-Adapted Perturbation Theory (SAPT). The ion pairs include imidazolium and pyrrolidinium cations combined with anions that are routinely used in the field of ionic liquids. The aug-cc-pVDZ, aug-cc-pVTZ, and 6-311++G(d,p) basis sets were used for EFP, while SAPT2+3/aug-cc-pVDZ provided the benchmark energies. Differences between the two methods were found to be large, and strongly dependent on the anion type. For the aug-cc-pVTZ basis set, which produced the least errors, average relative errors were between 2.3% and 18.4% for pyrrolidinium ion pairs and between 2.1% and 27.7% for imidazolium ion pairs for each individual energetic component (excluding charge transfer), as well as the total interaction energy. Charge transfer gave the largest relative errors: 56% and 63% on average for pyrrolidinium- and imidazolium-based ion pairs, respectively. Scaling of the EFP components against SAPT2+3 showed improvement for polarization (induction) and dispersion terms, thus indicating potential for the development of cost-effective alternatives for intermolecular induction and dispersion potentials for ionic liquids. PMID:27116302

  3. Valence and ionic lowest-lying electronic states of ethyl formate as studied by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy, and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Śmiałek, M. A., E-mail: smialek@pg.gda.pl [Department of Control and Energy Engineering, Faculty of Ocean Engineering and Ship Technology, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk (Poland); Łabuda, M.; Guthmuller, J. [Department of Theoretical Physic and Quantum Information, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk (Poland); Hubin-Franskin, M.-J.; Delwiche, J. [Département de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège (Belgium); Duflot, D. [Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Université Lille1 Sciences et Technologies, F-59655 Villeneuve d' Ascq Cedex (France); Mason, N. J. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Hoffmann, S. V.; Jones, N. C. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Building 1520, DK-8000 Aarhus C (Denmark); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2014-09-14

    The highest resolution vacuum ultraviolet photoabsorption spectrum of ethyl formate, C{sub 2}H{sub 5}OCHO, yet reported is presented over the wavelength range 115.0–275.5 nm (10.75–4.5 eV) revealing several new spectral features. Valence and Rydberg transitions and their associated vibronic series, observed in the photoabsorption spectrum, have been assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of ethyl formate and are compared with a newly recorded He(I) photoelectron spectrum (from 10.1 to 16.1 eV). New vibrational structure is observed in the first photoelectron band. The photoabsorption cross sections have been used to calculate the photolysis lifetime of ethyl formate in the upper stratosphere (20–50 km)

  4. Functional ionic liquids

    International Nuclear Information System (INIS)

    In the thesis at hand, new functional ionic liquids were investigated. Main focus was attended to their structure property relations and the structural features leading to a decrease of the melting point. New compounds of the type 1-butyl-3-methylimidazolium tris(N,Ndialkyldithiocarbamato) uranylate with variously substituated dithiocarbamato ligands were synthesized and characterized. Ligands with asymmetrical substitution pattern proved to be most suitable for ionic liquid formation. The single-crystal X-ray structures revealed the interactions in the solid state. Here, the first spectroscopic investigation of the U-S bond in sulfur donated uranyl complexes, up to now only observed in single-crystal X-ray structures, is presented, and the participation of the uranium f-orbitals is shown by theoretical calculations. Electrochemical investigations showed the accessibility of the respective UVO2+ compounds. As well, ionic liquids with [FeCl4]- and [Cl3FeOFeCl3]2- as anion were synthesized. Both of these anions contain high-spin Fe(III) centres in distorted tetrahedral environment, but exhibit different magnetic behaviour. The tetrachloroferrates show the usual paramagnetism, the m-oxobis(trichloroferrate) exhibits unexpectedly strong antiferromagnetic coupling, as was observed by NMR experiments and susceptibility measurements. To investigate structure-property relations in functionalized ionic liquids, a set of protic, primary alkylammonium and aprotic, quarternary trimethylalkylammonium based ionic liquids was synthesized, and characterized. The length of the alkyl chain was systematically varied, and all compounds were synthesized with and without hydroxyl group, as well as formate and bis(triflyl)amide salts, aiming at getting insight into the influence of the different structure parts on the respective ionic liquid's properties.

  5. Multi-species biofilm of Candida albicans and non-Candida albicans Candida species on acrylic substrate

    Directory of Open Access Journals (Sweden)

    Apurva K Pathak

    2012-02-01

    Full Text Available OBJECTIVE: In polymicrobial biofilms bacteria extensively interact with Candida species, but the interaction among the different species of the Candida is yet to be completely evaluated. In the present study, the difference in biofilm formation ability of clinical isolates of four species of Candida in both single-species and multi-species combinations on the surface of dental acrylic resin strips was evaluated. MATERIAL AND METHODS: The species of Candida, isolated from multiple species oral candidiasis of the neutropenic patients, were used for the experiment. Organisms were cultured on Sabouraud dextrose broth with 8% glucose (SDB. Biofilm production on the acrylic resins strips was determined by crystal violet assay. Student's t-test and ANOVA were used to compare in vitro biofilm formation for the individual species of Candida and its different multi-species combinations. RESULTS: In the present study, differences between the mean values of the biofilm-forming ability of individual species (C. glabrata>C. krusei>C. tropicalis>C. albicans and in its multi-species' combinations (the highest for C. albicans with C. glabrata and the lowest for all the four species combination were reported. CONCLUSIONS: The findings of this study showed that biofilm-forming ability was found greater for non-Candida albicans Candida species (NCAC than for C. albicans species with intra-species variation. Presence of C. albicans in multi-species biofilms increased, whereas; C. tropicalis decreased the biofilm production with all other NCAC species.

  6. Balance of interactions determines optimal survival in multi-species communities

    CERN Document Server

    Choudhary, Anshul

    2015-01-01

    We consider a multi-species community modelled as a complex network of populations, where the links are given by a random asymmetric matrix J, with fraction 1-C of zero entries, where C reflects the over-all connectivity of the system. The non-zero elements of J are drawn from a gaussian distribution with mean 'mu' and standard deviation . The signs of the elements J reflect the nature of density-dependent interactions, such as predatory-prey, mutualism or competition, and their magnitudes reflect the strength of the interaction. In this study we try to uncover the broad features of the interspecies interactions that determine the global robustness of this network, as indicated by the average number of active nodes (i.e. non-extinct species) in the network, and the total population, reflecting the biomass yield. We find that the network transitions from a completely extinct system to one where all nodes are active, as the mean interaction strength goes from negative to positive. We also find that the total po...

  7. Variational wavefunction for multi-species spinful fermionic superfluids and superconductors

    International Nuclear Information System (INIS)

    We introduce a new fermionic variational wavefunction, generalizing the Bardeen–Cooper–Schrieffer (BCS) wavefunction, which is suitable for interacting multi-species spinful systems and sustaining superfluidity. Applications range from quark matter to the high temperature superconductors. A wide class of Hamiltonians, comprising interactions and hybridization of arbitrary momentum dependence between different fermion species, can be treated in a comprehensive manner. This is the case, as both the intra-species and the inter-species interactions are treated on equally rigorous footing, which is accomplished via the introduction of a new quantum index attached to the fermions. The index is consistent with known fermionic physics, and allows for heretofore unaccounted fermion–fermion correlations. We have derived the finite temperature version of the theory, thus obtaining the renormalized quasiparticle dispersion relations, and we discuss the appearance of charge and spin density wave order. We present numerical solutions for two electron species in 2 dimensions. Based on these solutions, we show that, for equivalent spin up and down fermions, the Fermi occupation factor (per spin) equals 1/2 deep in the Fermi sea. This constitutes a unique experimental prediction of the theory, both for the normal and superfluid states. Interestingly, this result, obtained in the thermodynamic limit, is consistent with Fermi occupation factor (in-)equalities for finite systems of electrons, derived (in a different context) by Borland and Dennis (1972) and by Altunbulak and Klyachko (2008)

  8. Toward Visible-Wavelength Multi-Species Trapped-Ion Quantum Logic

    Science.gov (United States)

    Bruzewicz, Colin; McConnell, Robert; Loh, William; Sage, Jeremy; Chiaverini, John

    2016-05-01

    Large-scale quantum information processing and quantum networking using trapped ions will likely require multiple atomic species to allow for sympathetic cooling of ion vibrational modes, quantum state measurement without decoherence of unmeasured qubits, and interfacing with flying qubits. Inter-species quantum logic and quantum state transfer are key components of these tasks, particularly in the cases of quantum-error-correction syndrome extraction or remote entanglement generation using sympathetic ions. Multi-species logic and manipulation in a large processor will require control light of several wavelengths delivered to many ion-trap array sites in parallel, a challenge at short wavelengths. We report on progress toward sympathetic cooling and intra- and inter-species logic using Sr+ and Ca+ ions in surface-electrode trap arrays. These species admit optical control fields that can be routed using photonic waveguides straightforwardly integrated into the trap-array structure as their relevant transitions are accessible using visible and near-infra-red light.

  9. Non-intrusive, on-line, simultaneous multi-species impurity monitoring in hydrogen using LIBS

    Science.gov (United States)

    Eseller, K. E.; Yueh, F.-Y.; Singh, J. P.

    2011-03-01

    Laser-induced breakdown spectroscopy (LIBS) has been evaluated for on-line, simultaneous multi-species impurity monitoring in hydrogen. A miniature spectrometer with spectral coverage of 620-800 nm and a gated detection system with spectral coverage of 40 nm were both used to record LIBS spectra from the spark produced in sample gas by a frequency-doubled Nd YAG laser. The effect of pressure on detecting the impurity (e.g., nitrogen, argon, and oxygen) in hydrogen was studied. LIBS spectra with different impurity levels of nitrogen, argon, and oxygen were recorded, and the intensity of the spectral lines of Ar, O, N, and H observed were used to form calibration plots for impurity measurement. The limits of detection (LODs) for oxygen, argon, and nitrogen in hydrogen were estimated from the calibration obtained with both the gated and ungated detection. The hydrogen impurity measurements based on the ungated miniature system show reliable and reproductive results. But the LODs with this system are about four times higher than the LODs obtained with a gated detection system in this work.

  10. Multi-dimensional multi-species modeling of transient electrodeposition in LIGA microfabrication.

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Gregory Herbert (Sandia National Laboratories, Livermore, CA); Chen, Ken Shuang

    2004-06-01

    This report documents the efforts and accomplishments of the LIGA electrodeposition modeling project which was headed by the ASCI Materials and Physics Modeling Program. A multi-dimensional framework based on GOMA was developed for modeling time-dependent diffusion and migration of multiple charged species in a dilute electrolyte solution with reduction electro-chemical reactions on moving deposition surfaces. By combining the species mass conservation equations with the electroneutrality constraint, a Poisson equation that explicitly describes the electrolyte potential was derived. The set of coupled, nonlinear equations governing species transport, electric potential, velocity, hydrodynamic pressure, and mesh motion were solved in GOMA, using the finite-element method and a fully-coupled implicit solution scheme via Newton's method. By treating the finite-element mesh as a pseudo solid with an arbitrary Lagrangian-Eulerian formulation and by repeatedly performing re-meshing with CUBIT and re-mapping with MAPVAR, the moving deposition surfaces were tracked explicitly from start of deposition until the trenches were filled with metal, thus enabling the computation of local current densities that potentially influence the microstructure and frictional/mechanical properties of the deposit. The multi-dimensional, multi-species, transient computational framework was demonstrated in case studies of two-dimensional nickel electrodeposition in single and multiple trenches, without and with bath stirring or forced flow. Effects of buoyancy-induced convection on deposition were also investigated. To further illustrate its utility, the framework was employed to simulate deposition in microscreen-based LIGA molds. Lastly, future needs for modeling LIGA electrodeposition are discussed.

  11. Titan's induced magnetosphere under non-ideal upstream conditions: 3D multi-species hybrid simulations

    Science.gov (United States)

    Simon, Sven; Motschmann, Uwe

    2009-12-01

    A 3D, multi-species hybrid model (kinetic ions, fluid electrons) has been applied to the interaction between Saturn's largest satellite Titan and the plasma in the giant planet's outer magnetosphere. In contrast to the idealized picture deduced from Voyager 1 data, recent observations made by the Cassini magnetometer instrument suggest that the ambient magnetic field is not directed perpendicular to Titan's orbital plane. Therefore, our purpose is to investigate systematically how Titan's induced magnetosphere is affected by a tilt of the upstream magnetic field. In the first part of our study, the structure of Titan's induced magnetosphere is analyzed as a function of the angle between the ambient magnetic field B and the bulk velocity u of the corotating plasma flow. Our simulations show that introducing a flow-aligned magnetic field component goes along with an asymmetrization of Titan's magnetotail, in addition to the asymmetry that already arises from the large gyroradii of the ion species involved in the interaction. In the vicinity of Titan, the field lines become strongly twisted, permitting the wakeside magnetic lobe structure to even penetrate into the satellite's geometric plasma shadow. However, despite the increased complexity of Titan's magnetic environment, the overall characteristics of the pick-up tail remain practically the same as in the case of "ideal" magnetic field orientation (B⊥u). In the second part of our study, we investigate in real-time the transition that Titan's plasma interaction undergoes during a change of the ambient magnetic field direction. In contrast to earlier analyses of Titan's plasma environment under non-stationary upstream conditions, the tilt of the ambient magnetic field is again taken into account. While in the case of B being perpendicular to u, the reconfiguration of Titan's induced magnetosphere is mainly governed by reconnection, our simulations suggest that when a flow-aligned field component is included

  12. On the potential of GHG emissions estimation by multi-species inverse modeling

    Science.gov (United States)

    Gerbig, Christoph; Boschetti, Fabio; Filges, Annette; Marshall, Julia; Koch, Frank-Thomas; Janssens-Maenhout, Greet; Nedelec, Philippe; Thouret, Valerie; Karstens, Ute

    2016-04-01

    Reducing anthropogenic emissions of greenhouse gases is one of the most important elements in mitigating climate change. However, as emission reporting is often incomplete or incorrect, there is a need to independently monitor the emissions. Despite this, in the case of CO2 one typically assumes that emissions from fossil fuel burning are well known, and only natural fluxes are constrained by atmospheric measurements via inverse modelling. On the other hand, species such as CO2, CH4, and CO often have common emission patterns, and thus share part of the uncertainties, both related to the prior knowledge of emissions, and to model-data mismatch error. We implemented the Lagrangian transport model STILT driven by ECMWF analysis and short-term forecast meteorological fields together with emission sector and fuel-type specific emissions of CO2, CH4 and CO from EDGARv4.3 at a spatial resolution of 0.1 x 0.1 deg., providing an atmospheric fingerprint of anthropogenic emissions for multiple trace gases. We combine the regional STILT simulations with lateral boundary conditions for CO2 and CO from MACC forecasts and CH4 from TM3 simulations. Here we apply this framework to airborne in-situ measurements made in the context of IAGOS (In-service Aircraft for a Global Observing System) and in the context of a HALO mission conducted for testing the active remote sensing system CHARM-F during April/May 2015 over central Europe. Simulated tracer distributions are compared to observed profiles of CO2, CH4, and CO, and the potential for a multi-species inversion using synergies between different tracers is assessed with respect to the uncertainty reduction in retrieved emission fluxes. Implications for inversions solving for anthropogenic emissions using atmospheric observations from ICOS (Integrated Carbon Observing System) are discussed.

  13. Multi-species biofilm of Candida albicans and non-Candida albicans Candida species on acrylic substrate

    OpenAIRE

    Apurva K Pathak; Sanjay Sharma; Pallavi Shrivastva

    2012-01-01

    OBJECTIVE: In polymicrobial biofilms bacteria extensively interact with Candida species, but the interaction among the different species of the Candida is yet to be completely evaluated. In the present study, the difference in biofilm formation ability of clinical isolates of four species of Candida in both single-species and multi-species combinations on the surface of dental acrylic resin strips was evaluated. MATERIAL AND METHODS: The species of Candida, isolated from multiple species oral...

  14. Multi-species spawning synchrony within scleractinian coral assemblages in the Red Sea

    KAUST Repository

    Bouwmeester, Jessica

    2014-09-21

    Early work on coral reproduction in the far northern Red Sea suggested that the spawning times of ecologically abundant species did not overlap, unlike on the Great Barrier Reef where many species spawn with high synchrony. In contrast, recent work in the northern and central Red Sea indicates a high degree of synchrony in the reproductive condition of Acropora species: over 90 % of species sampled in April/May contain mature gametes. However, it has yet to be determined when most Acropora release their gametes. In addition, there is a lack of data for other ecologically important scleractinian species such as merulinids and poritids. Here, we document the date and time of spawning for 51 species in the central Red Sea over three consecutive years, and the month of spawning for an additional 17 species inferred from the presence of mature gametes. Spawning occurs on nights around the full moon, the spawning season lasts at least 4 months from April until July, and observations are consistent with the few other records from the Red Sea. The number of Acropora species spawning was highest in April with 13 species spawning two nights before the full moon in 2011, 13 species spawning on the night of the full moon in 2012, and eight species spawning four nights after the full moon in 2013. The total number of species spawning was high in April, May, and June and involved 15–19 species per month in 2012. Only four species spawned in July 2012. Few regions worldwide have been similarly sampled and include the Philippines, Okinawa in Japan, and Palau, where spawning patterns are very similar to those in the central Red Sea and where corals spawn on nights around the full moon over a period of 3–4 months. In particular, in all four locations, Acropora are among the first species to spawn. Our results add to a growing body of evidence indicating that multi-species spawning synchrony is a feature of all speciose coral assemblages.

  15. Interplay between subsurface structural heterogeneity and multi-species reactive transport in human health risk predictions

    Science.gov (United States)

    Henri, C.; Fernandez-Garcia, D.; de Barros, F.

    2013-12-01

    The increasing presence of toxic chemicals released in the subsurface has led to a rapid growth of social concerns and to the need to develop and employ models that can predict the impact of groundwater contamination in human health under uncertainty. Monitored natural attenuation is a common remediation action in many contamination cases and represents an attractive decontamination method. However, natural attenuation can lead to the production of subspecies of distinct toxicity that may pose challenges in pollution management strategies. The actual threat that these contaminants pose to human health and ecosystems greatly depends on the interplay between the complexity of the geological system and the toxicity of the pollutants and their byproducts. In this work, we examine the interplay between multispecies reactive transport and the heterogeneous structure of the contaminated aquifer on human health risk predictions. The structure and organization of hydraulic properties of the aquifer can lead to preferential flow channels and fast contamination pathways. Early travel times, associated to channeling effects, are intuitively perceived as an indicator for high risk. However, in the case of multi-species systems, early travel times may also lead a limited production of daughter species that may contain higher toxicity as in the case of chlorinated compounds. In this work, we model a Perchloroethylene (PCE) contamination problem followed by the sequential first-order production/biodegradation of its daughter species Trichloroethylene (TCE), Dichloroethylene (DCE) and Vinyl Chlorine (VC). For this specific case, VC is known to be a highly toxic contaminant. By performing numerical experiments, we evaluate transport for two distinct three-dimensional aquifer structures. First, a multi-Gaussian hydraulic conductivity field and secondly, a geostatistically equivalent connected field. These two heterogeneity structures will provide two distinct ranges of mean travel

  16. Pasture intake and milk production of dairy cows rotationally grazing on multi-species swards.

    Science.gov (United States)

    Roca-Fernández, A I; Peyraud, J L; Delaby, L; Delagarde, R

    2016-09-01

    Increasing plant species diversity has been proposed as a means for enhancing annual pasture productivity and decreasing seasonal variability of pasture production facing more frequent drought scenarios due to climate change. Few studies have examined how botanical complexity of sown swards affects cow performance. A 2-year experiment was conducted to determine how sward botanical complexity, from a monoculture of ryegrass to multi-species swards (MSS) (grasses-legumes-forb), affect pasture chemical composition and nutritive value, pasture dry matter (DM) intake, milk production and milk solids production of grazing dairy cows. Five sward species: perennial ryegrass (L as Lolium), white clover and red clover (both referred to as T as Trifolium because they were always sown together), chicory (C as Cichorium) and tall fescue (F as Festuca) were assigned to four grazing treatments by combining one (L), three (LT), four (LTC) or five (LTCF) species. Hereafter, the LT swards are called mixed swards as a single combination of ryegrass and clovers, whereas LTC and LTCF swards are called MSS as a combination of at least four species from three botanical families. The experimental area (8.7 ha) was divided into four block replicates with a mineral nitrogen fertilisation of 75 kg N/ha per year for each treatment. In total, 13 grazing rotations were carried out by applying the same grazing calendar and the same pasture allowance of 19 kg DM/cow per day above 4 cm for all treatments. Clover represented 20% of DM for mixed and MSS swards; chicory represented 30% of DM for MSS and tall fescue represented 10% of DM for LTCF swards. Higher milk production (+1.1 kg/day) and milk solids production (+0.08 kg/day) were observed for mixed swards than for ryegrass swards. Pasture nutritive value and pasture DM intake were unaffected by the inclusion of clover. Pasture DM, organic matter and NDF concentrations were lower for MSS than for mixed swards. Higher milk production (+0.8 kg

  17. Balance of Interactions Determines Optimal Survival in Multi-Species Communities

    Science.gov (United States)

    Choudhary, Anshul; Sinha, Sudeshna

    2015-01-01

    We consider a multi-species community modelled as a complex network of populations, where the links are given by a random asymmetric connectivity matrix J, with fraction 1 − C of zero entries, where C reflects the over-all connectivity of the system. The non-zero elements of J are drawn from a Gaussian distribution with mean μ and standard deviation σ. The signs of the elements Jij reflect the nature of density-dependent interactions, such as predatory-prey, mutualism or competition, and their magnitudes reflect the strength of the interaction. In this study we try to uncover the broad features of the inter-species interactions that determine the global robustness of this network, as indicated by the average number of active nodes (i.e. non-extinct species) in the network, and the total population, reflecting the biomass yield. We find that the network transitions from a completely extinct system to one where all nodes are active, as the mean interaction strength goes from negative to positive, with the transition getting sharper for increasing C and decreasing σ. We also find that the total population, displays distinct non-monotonic scaling behaviour with respect to the product μC, implying that survival is dependent not merely on the number of links, but rather on the combination of the sparseness of the connectivity matrix and the net interaction strength. Interestingly, in an intermediate window of positive μC, the total population is maximal, indicating that too little or too much positive interactions is detrimental to survival. Rather, the total population levels are optimal when the network has intermediate net positive connection strengths. At the local level we observe marked qualitative changes in dynamical patterns, ranging from anti-phase clusters of period 2 cycles and chaotic bands, to fixed points, under the variation of mean μ of the interaction strengths. We also study the correlation between synchronization and survival, and find that

  18. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Sabine Laschat; Axenov, Kirill V

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  19. S K-edge XAS and DFT Calculations on Cytochrome P450: Covalent and Ionic Contributions to the Cysteine-Fe Bond and Their Contribution to Reactivity

    OpenAIRE

    Dey, Abhishek; Jiang, Yonging; de Montellano, Paul Ortiz; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.

    2009-01-01

    Experimental covalencies of the Fe-S bond for the resting low-spin and substrate-bound high-spin active site of cytochrome P450 are reported. DFT calculations on the active site indicate that one H-bonding interaction from the protein backbone is needed to reproduce the experimental values. The H-bonding to the thiolate from the backbone decreases the anisotropic π covalency of the Fe-S bond lowering the barrier of free rotation of the exchangeable axial ligand, which is important for reactiv...

  20. Short-range incommensurate d-wave charge order from a two-loop renormalization group calculation of the ferm-ionic hot spot model

    Science.gov (United States)

    Freire, Hermann; de Carvalho, Vanuildo

    2015-03-01

    The two-loop renormalization group (RG) calculation is considerably extended here for a two-dimensional (2D) fermionic effective field theory model, which includes only the so-called ``hot spots'' that are connected by the spin-density-wave (SDW) ordering wavevector on a Fermi surface generated by the 2D t -t' Hubbard model at low hole doping. We compute the Callan-Symanzik RG equation up to two loops describing the flow of the single-particle Green's function, the corresponding spectral function, the Fermi velocity, and some of the most important order-parameter susceptibilities in the model at lower energies. As a result, we establish that - in addition to clearly dominant SDW correlations - an approximate (pseudospin) symmetry relating a short-range incommensurate d-wave charge order to the d-wave superconducting order indeed emerges at lower energy scales, which is in agreement with recent works available in the literature addressing the 2D spin-fermion model. We derive implications of this possible electronic phase in the ongoing attempt to describe the phenomenology of the pseudogap regime in underdoped cuprates. We acknowledge financial support from CNPq under Grant No. 245919/2012-0 and FAPEG under Grant No. 201200550050248 for this project.

  1. Acidic Ionic Liquids.

    Science.gov (United States)

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition. PMID:27175515

  2. A development of multi-Species mass transport model considering thermodynamic phase equilibrium

    DEFF Research Database (Denmark)

    Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn

    2008-01-01

    ) variation in solid-phase composition when using different types of cement, (ii) physicochemical evaluation of steel corrosion initiation behaviour by calculating the molar ratio of chloride ion to hydroxide ion [Cl]/[OH] in pore solution, (iii) complicated changes of solid-phase composition caused by the...

  3. Nonionic and ionic surfactants at an interface

    OpenAIRE

    Onuki, Akira

    2008-01-01

    A Ginzburg-Landau theory is presented on surfactants in polar binary mixtures, which aggregate at an interface due to the amphiphilic interaction. They can be ionic surfactants coexisting with counterions. Including the solvation and image interactions and accounting for a finite volume fraction of the surfactant, we obtain their distributions and the electric potential around an interface in equilibrium. The surface tension is also calculated. The distribution of the adsorbed ionic surfactan...

  4. Hierarchical multi-species modeling of carnivore responses to hunting, habitat and prey in a West African protected area.

    Directory of Open Access Journals (Sweden)

    A Cole Burton

    Full Text Available Protected areas (PAs are a cornerstone of global efforts to shield wildlife from anthropogenic impacts, yet their effectiveness at protecting wide-ranging species prone to human conflict--notably mammalian carnivores--is increasingly in question. An understanding of carnivore responses to human-induced and natural changes in and around PAs is critical not only to the conservation of threatened carnivore populations, but also to the effective protection of ecosystems in which they play key functional roles. However, an important challenge to assessing carnivore communities is the often infrequent and imperfect nature of survey detections. We applied a novel hierarchical multi-species occupancy model that accounted for detectability and spatial autocorrelation to data from 224 camera trap stations (sampled between October 2006 and January 2009 in order to test hypotheses about extrinsic influences on carnivore community dynamics in a West African protected area (Mole National Park, Ghana. We developed spatially explicit indices of illegal hunting activity, law enforcement patrol effort, prey biomass, and habitat productivity across the park, and used a Bayesian model selection framework to identify predictors of site occurrence for individual species and the entire carnivore community. Contrary to our expectation, hunting pressure and edge proximity did not have consistent, negative effects on occurrence across the nine carnivore species detected. Occurrence patterns for most species were positively associated with small prey biomass, and several species had either positive or negative associations with riverine forest (but not with other habitat descriptors. Influences of sampling design on carnivore detectability were also identified and addressed within our modeling framework (e.g., road and observer effects, and the multi-species approach facilitated inference on even the rarest carnivore species in the park. Our study provides insight for the

  5. Hierarchical multi-species modeling of carnivore responses to hunting, habitat and prey in a West African protected area.

    Science.gov (United States)

    Burton, A Cole; Sam, Moses K; Balangtaa, Cletus; Brashares, Justin S

    2012-01-01

    Protected areas (PAs) are a cornerstone of global efforts to shield wildlife from anthropogenic impacts, yet their effectiveness at protecting wide-ranging species prone to human conflict--notably mammalian carnivores--is increasingly in question. An understanding of carnivore responses to human-induced and natural changes in and around PAs is critical not only to the conservation of threatened carnivore populations, but also to the effective protection of ecosystems in which they play key functional roles. However, an important challenge to assessing carnivore communities is the often infrequent and imperfect nature of survey detections. We applied a novel hierarchical multi-species occupancy model that accounted for detectability and spatial autocorrelation to data from 224 camera trap stations (sampled between October 2006 and January 2009) in order to test hypotheses about extrinsic influences on carnivore community dynamics in a West African protected area (Mole National Park, Ghana). We developed spatially explicit indices of illegal hunting activity, law enforcement patrol effort, prey biomass, and habitat productivity across the park, and used a Bayesian model selection framework to identify predictors of site occurrence for individual species and the entire carnivore community. Contrary to our expectation, hunting pressure and edge proximity did not have consistent, negative effects on occurrence across the nine carnivore species detected. Occurrence patterns for most species were positively associated with small prey biomass, and several species had either positive or negative associations with riverine forest (but not with other habitat descriptors). Influences of sampling design on carnivore detectability were also identified and addressed within our modeling framework (e.g., road and observer effects), and the multi-species approach facilitated inference on even the rarest carnivore species in the park. Our study provides insight for the conservation

  6. Seabirds maintain offspring provisioning rate despite fluctuations in prey abundance: A multi-species functional response for guillemots in the North Sea

    DEFF Research Database (Denmark)

    Smout, Sophie; Rindorf, Anna; Wanless, Sarah;

    2013-01-01

    links consumption rates to the availability of multiple prey types, but fitting multi-species functional responses to field data can be difficult, requiring consumption measurements over a range of different prey abundances. Such detailed data may be especially difficult to obtain in marine ecosystems....... 3. We used annual time-series data on chick provisioning for the common guillemot Uria aalge together with abundance indices for its two main prey (lesser sandeel Ammodytes marinus and sprat Sprattus sprattus) to parameterize a multi-species functional response for parents provisioning chicks...... their parents despite fluctuating prey abundances, conferring some resilience in the face of environmental variation. The parameterized multi-species functional response model can be used to estimate levels of severe prey shortage that compromise provisioning. It also enables us to interpret predator...

  7. Multi-species beam hardening calibration device for x-ray microtomography

    Science.gov (United States)

    Evershed, Anthony N. Z.; Mills, David; Davis, Graham

    2012-10-01

    Impact-source X-ray microtomography (XMT) is a widely-used benchtop alternative to synchrotron radiation microtomography. Since X-rays from a tube are polychromatic, however, greyscale `beam hardening' artefacts are produced by the preferential absorption of low-energy photons in the beam path. A multi-material `carousel' test piece was developed to offer a wider range of X-ray attenuations from well-characterised filters than single-material step wedges can produce practically, and optimization software was developed to produce a beam hardening correction by use of the Nelder-Mead optimization method, tuned for specimens composed of other materials (such as hydroxyapatite [HA] or barium for dental applications.) The carousel test piece produced calibration polynomials reliably and with a significantly smaller discrepancy between the calculated and measured attenuations than the calibration step wedge previously in use. An immersion tank was constructed and used to simplify multi-material samples in order to negate the beam hardening effect of low atomic number materials within the specimen when measuring mineral concentration of higher-Z regions. When scanned in water at an acceleration voltage of 90 kV a Scanco AG hydroxyapatite / poly(methyl methacrylate) calibration phantom closely approximates a single-material system, producing accurate hydroxyapatite concentration measurements. This system can then be corrected for beam hardening for the material of interest.

  8. Stability of Ionic Colloidal Crystals (ICCs)

    Science.gov (United States)

    Maskaly, Garry R.; Garcia, R. Edwin; Carter, W. Craig; Chiang, Yet-Ming

    2003-03-01

    Ionic colloidal crystals (ICCs) are here defined as ordered multicomponent colloids formed by attractive electrostatic interactions. Compared to previous approaches to colloidal crystallization, the ICC approach holds the potential for self-assembly of a wide range of structures not easily accessible by other methods. In this work, the colloid-chemical conditions under which ICCs are stable have been theoretically analyzed. A model is presented in which two dimensionless parameters are found to fully characterize an ICC system. We calculate the Madelung constant for ICCs of several classical ionic crystal structures as a function of these two parameters, and discuss the parallels between the ICC Madelung constants and the classical ionic case. Experimentally accessible regions of surface charge, particle sizes, salt concentration, and temperature where ionic colloidal crystallization should be possible are identified.

  9. Quantized ionic conductance in nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Zwolak, Michael [Los Alamos National Laboratory; Lagerqvist, Johan [UCSD; Di Ventra, Massimilliano [UCSD

    2009-01-01

    Ionic transport in nanopores is a fundamentally and technologically important problem in view of its ubiquitous occurrence in biological processes and its impact on DNA sequencing applications. Using microscopic calculations, we show that ion transport may exhibit strong non-liDearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. Once in the pore, the water molecules form wavelike structures due to multiple scattering at the surface of the pore walls and interference with the radial waves around the ion. We discuss these effects as well as the conditions under which the step-like features in the ionic conductance should be experimentally observable.

  10. sRNAbench: profiling of small RNAs and its sequence variants in single or multi-species high-throughput experiments

    Czech Academy of Sciences Publication Activity Database

    Barturen, G.; Rueda, A.; Hamberg, M.; Alganza, A.; Lebron, R.; Kotsyfakis, Michalis; Shi, B.-J.; Koppers-Lalic, D.; Hackenberg, M.

    2014-01-01

    Roč. 1, SEP 30 2014 (2014), s. 21-31. ISSN 2084-7173 Institutional support: RVO:60077344 Keywords : microRNA * small RNA * isomiRs * expression profiling * multi-species experiment * webserver Subject RIV: EB - Genetics ; Molecular Biology

  11. CAUSE OF A MULTI-SPECIES RADIOIODINE PLUME THAT IS INCREASING IN CONCENTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, D.

    2010-09-30

    Field and laboratory studies were carried out to understand the cause for steady increases in {sup 129}I concentrations emanating from radiological seepage basins located on the Savannah River Site. The basins were closed in 1988 by adding limestone and blast furnace slag and then capping with a RCRA low permeability engineered cover. Groundwater {sup 129}I concentrations in a well near the seepage basin in 1993 were 200 pCi L{sup -1} and are presently between 400 and 1000 pCi L{sup -1}. Iodine speciation in the plume was not uniform. Near the source, the iodine was comprised of 86% iodide, 2% iodate, and 12% organo-iodine (total activity = 178 pCi L{sup -1}). Whereas, groundwater iodine speciation 365 m down stream (25 m up stream from a wetland) was 0% iodide, 93% iodate, and 7% organo iodine. Batch desorption studies demonstrated that high concentrations of {sup 129}I could be incrementally desorbed from an archived seepage basin sediment sample by raising the pH. Batch sorption studies showed that iodate, IO{sub 3}{sup -}, sorbed more strongly than iodide, I{sup -}, to a subsurface clayey sediment, but equally well as iodide to a subsurface sandy sediment and a wetland sediment. Placing an organic-rich wetland sediment, but not nearby mineral sediments, under reducing (or microaerobic) conditions resulted in a large decrease in iodide K{sub d} values (from 73 to 10 mL g{sup -1}) and iodate K{sub d} values (from 80 to 7 mL g{sup -1}). Between pH and reduction-oxidation potential, it appears that pH seems to have a stronger influence on iodide and iodate sorption to mineral sediment. This may not be true for sediments containing higher concentrations of organic matter, such as the 7.6% organic matter sediment used in this study. First order calculations based on desorption studies with seepage basin sediments indicate that the modest increase of 0.7 pH units detected in the study site groundwater over the last 17 years since closure of the seepage basin may be

  12. The formaldehyde budget as seen by a global-scale multi-constraint and multi-species inversion system

    Directory of Open Access Journals (Sweden)

    A. Fortems-Cheiney

    2012-03-01

    Full Text Available For the first time, carbon monoxide (CO and formaldehyde (HCHO satellite retrievals have been used together with methane (CH4 and methyl choloroform (CH3CCl3 or MCF surface measurements in a complex inversion system. The CO and HCHO are, respectively from MOPITT and OMI instruments. The multi-species and multi-satellite dataset inversion is done for the 2005–2008 period. The robustness of our results is evaluated by comparing our posterior-modeled concentrations with several sets of independent measurements of atmospheric mixing ratios. The inversion results lead to significant changes from the prior to the posterior, in terms of magnitude and seasonality of the CO and CH4 surface fluxes and of the 3-D HCHO production by non-methane volatile organic compounds (NMVOCs. The latter is significantly decreased, indicating an overestimation of the biogenic NMVOCs emissions, such as isoprene, in the GEIA inventory. CO and CH4 surface emissions are increased by the inversion, from 1037 to 1409 Tg CO and from 489 to 528 TgCH4 on average for the 2005–2008 period. CH4 emissions present significant interannual variability and a joint CO–CH4 fluxes analysis reveals that tropical biomass burning probably played a role in the recent increase of atmospheric methane.

  13. Modulation of the intestinal microbiota and morphology of tilapia, Oreochromis niloticus, following the application of a multi-species probiotic.

    Science.gov (United States)

    Standen, B T; Rodiles, A; Peggs, D L; Davies, S J; Santos, G A; Merrifield, D L

    2015-10-01

    The intestinal microbiota and morphology of tilapia (Oreochromis niloticus) were investigated after the application of a multi-species probiotic containing Lactobacillus reuteri, Bacillus subtilis, Enterococcus faecium and Pediococcus acidilactici (AquaStar(®) Growout). Tilapia (55.03 ± 0.44 g) were fed either a control diet or a probiotic diet (control diet supplemented with AquaStar(®) Growout at 5 g kg(-1)). After four and eight weeks, culture-dependent analysis showed higher levels of lactic acid bacteria (LAB), enterococci and Bacillus spp. in the mucosa and digesta of fish fed AquaStar(®) Growout. At week four, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) revealed a higher similarity within the probiotic fed replicates than replicates of the control group; after eight weeks, the compositional dissimilarity of the microbiome profiles between the groups was greater than the dissimilarities within each group (P 99 % of reads). Bacillus, Cetobacterium and Mycobacterium were the dominant genera in the digesta of control fish whereas Bacillus, Enterococcus and Pediococcus were the largest constituents in probiotic-fed fish. The addition of AquaStar(®) Growout to tilapia diets led to increased populations of intraepithelial leucocytes, a higher absorptive surface area index and higher microvilli density in the intestine. These data suggest that AquaStar(®) Growout can modulate both the intestinal microbiota and morphology of tilapia. PMID:26115752

  14. Assessing gear modifications needed to optimize yields in a heavily exploited, multi-species, seagrass and coral reef fishery.

    Directory of Open Access Journals (Sweden)

    Christina C Hicks

    Full Text Available Effective management is necessary if small-scale fisheries, such as those found in mixed habitats including seagrass and coral reefs, are to continue providing food for many of the poorest communities of the world. Gear-based management, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in seagrass and coral reef fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. Using a unique dataset, containing ten years of species level length frequency catch data from a multi-gear, multi-species seagrass and coral reef fishery in Kenya, we evaluate species specific fishery statuses, compare gear use to gear regulations and estimate the potential needs for further gear restrictions. Despite the high diversity of the fishery, fifteen species represented over 90% of the catch, and only three species represented 60% of the catch. The three most abundant species in the catch, Lethrinus lentjan (Lacepède, Siganus sutor (Valenciennes and Leptoscarus vaigiensis (Quoy & Gaimard all showed evidence of growth overfishing. Lethrinus lentjan, with an exploitation rate of 0.82, also shows evidence of recruitment overfishing. Current legal but weakly enforced gear restrictions are capable of protecting a significant portion of the catch up to maturity but optimization of yield will require that the current mesh size be increased from 6.3 to 8.8 and 9.2 cm to increase yields of L. lentjan and S. sutor, respectively. Given the difficulties of enforcing mesh size, we recommend that the economic benefits of these larger mesh sizes be communicated and enforced through co-management. This abstract is also available in Kiswahili (Abstract S1.

  15. Variation in Population Synchrony in a Multi-Species Seabird Community: Response to Changes in Predator Abundance.

    Directory of Open Access Journals (Sweden)

    Gail S Robertson

    Full Text Available Ecologically similar sympatric species, subject to typical environmental conditions, may be expected to exhibit synchronous temporal fluctuations in demographic parameters, while populations of dissimilar species might be expected to show less synchrony. Previous studies have tested for synchrony in different populations of single species, and those including data from more than one species have compared fluctuations in only one demographic parameter. We tested for synchrony in inter-annual changes in breeding population abundance and productivity among four tern species on Coquet Island, northeast England. We also examined how manipulation of one independent environmental variable (predator abundance influenced temporal changes in ecologically similar and dissimilar tern species. Changes in breeding abundance and productivity of ecologically similar species (Arctic Sterna paradisaea, Common S. hirundo and Roseate Terns S. dougallii were synchronous with one another over time, but not with a species with different foraging and breeding behaviour (Sandwich Terns Thalasseus sandvicensis. With respect to changes in predator abundance, there was no clear pattern. Roseate Tern abundance was negatively correlated with that of large gulls breeding on the island from 1975 to 2013, while Common Tern abundance was positively correlated with number of large gulls, and no significant correlations were found between large gull and Arctic and Sandwich Tern populations. Large gull abundance was negatively correlated with productivity of Arctic and Common Terns two years later, possibly due to predation risk after fledging, while no correlation with Roseate Tern productivity was found. The varying effect of predator abundance is most likely due to specific differences in the behaviour and ecology of even these closely-related species. Examining synchrony in multi-species assemblages improves our understanding of how whole communities react to long-term changes

  16. Ionic flotation of uranium from carbonate solutions

    International Nuclear Information System (INIS)

    Experimentally shown is principal possibility of uranium-bearing ion flotation extraction from diluted carbonate solutions using alkyl pyridinium bromides. Optimal conditions of flotation process are determined. The results on flotation are compared with the results of calculation of uranium-bearing solution ionic composition. The sublate nature is confirmed by the IR-spectroscopy method

  17. A mean field model for the collective behaviour of interacting multi-species particles: mathematical results and application to the inverse problem

    OpenAIRE

    Fedele, Micaela

    2011-01-01

    The study of the normalized sum of random variables and its asymptotic behaviour has been and continues to be a central chapter in probability and statistical mechanics. When those variables are independent the central limit theorem ensures that the sum with square-root normalization converges toward a Gaussian distribution. The main topic of this thesis is the generalization of the central limit theorem for spin random variable whose interaction is described by a multi-species mean-field Ham...

  18. Ionic Liquids in Tribology

    Directory of Open Access Journals (Sweden)

    Ichiro Minami

    2009-06-01

    Full Text Available Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided.

  19. Fullerol ionic fluids

    KAUST Repository

    Fernandes, Nikhil

    2010-01-01

    We report for the first time an ionic fluid based on hydroxylated fullerenes (fullerols). The ionic fluid was synthesized by neutralizing the fully protonated fullerol with an amine terminated polyethylene/polypropylene oxide oligomer (Jeffamine®). The ionic fluid was compared to a control synthesized by mixing the partially protonated form (sodium form) of the fullerols with the same oligomeric amine in the same ratio as in the ionic fluids (20 wt% fullerol). In the fullerol fluid the ionic bonding significantly perturbs the thermal transitions and melting/crystallization behavior of the amine. In contrast, both the normalized heat of fusion and crystallization of the amine in the control are similar to those of the neat amine consistent with a physical mixture of the fullerols/amine with minimal interactions. In addition to differences in thermal behavior, the fullerol ionic fluid exhibits a complex viscoelastic behavior intermediate between the neat Jeffamine® (liquid-like) and the control (solid-like). © 2010 The Royal Society of Chemistry.

  20. Interactions in ion pairs of protic ionic liquids: Comparison with aprotic ionic liquids

    International Nuclear Information System (INIS)

    The stabilization energies for the formation (Eform) of 11 ion pairs of protic and aprotic ionic liquids were studied by MP2/6-311G** level ab initio calculations to elucidate the difference between the interactions of ions in protic ionic liquids and those in aprotic ionic liquids. The interactions in the ion pairs of protic ionic liquids (diethylmethylammonium [dema] and dimethylpropylammonium [dmpa] based ionic liquids) are stronger than those of aprotic ionic liquids (ethyltrimethylammonium [etma] based ionic liquids). The Eform for the [dema][CF3SO3] and [dmpa][CF3SO3] complexes (−95.6 and −96.4 kcal/mol, respectively) are significantly larger (more negative) than that for the [etma][CF3SO3] complex (−81.0 kcal/mol). The same trend was observed for the calculations of ion pairs of the three cations with the Cl−, BF4−, TFSA− anions. The anion has contact with the N–H bond of the dema+ or dmpa+ cations in the most stable geometries of the dema+ and dmpa+ complexes. The optimized geometries, in which the anions locate on the counter side of the cations, are 11.0–18.0 kcal/mol less stable, which shows that the interactions in the ions pairs of protic ionic liquids have strong directionality. The Eform for the less stable geometries for the dema+ and dmpa+ complexes are close to those for the most stable etma+ complexes. The electrostatic interaction, which is the major source of the attraction in the ion pairs, is responsible for the directionality of the interactions and determining the magnitude of the interaction energy. Molecular dynamic simulations of the [dema][TFSA] and [dmpa][TFSA] ionic liquids show that the N–H bonds of the cations have contact with the negatively charged (oxygen and nitrogen) atoms of TFSA− anion, while the strong directionality of the interactions was not suggested from the simulation of the [etma][CF3SO3] ionic liquid

  1. Functional ionic liquids; Funktionelle ionische Fluessigkeiten

    Energy Technology Data Exchange (ETDEWEB)

    Baecker, Tobias

    2012-07-01

    In the thesis at hand, new functional ionic liquids were investigated. Main focus was attended to their structure property relations and the structural features leading to a decrease of the melting point. New compounds of the type 1-butyl-3-methylimidazolium tris(N,Ndialkyldithiocarbamato) uranylate with variously substituated dithiocarbamato ligands were synthesized and characterized. Ligands with asymmetrical substitution pattern proved to be most suitable for ionic liquid formation. The single-crystal X-ray structures revealed the interactions in the solid state. Here, the first spectroscopic investigation of the U-S bond in sulfur donated uranyl complexes, up to now only observed in single-crystal X-ray structures, is presented, and the participation of the uranium f-orbitals is shown by theoretical calculations. Electrochemical investigations showed the accessibility of the respective U{sup V}O{sub 2}{sup +} compounds. As well, ionic liquids with [FeCl{sub 4}]{sup -} and [Cl{sub 3}FeOFeCl{sub 3}]{sup 2-} as anion were synthesized. Both of these anions contain high-spin Fe(III) centres in distorted tetrahedral environment, but exhibit different magnetic behaviour. The tetrachloroferrates show the usual paramagnetism, the m-oxobis(trichloroferrate) exhibits unexpectedly strong antiferromagnetic coupling, as was observed by NMR experiments and susceptibility measurements. To investigate structure-property relations in functionalized ionic liquids, a set of protic, primary alkylammonium and aprotic, quarternary trimethylalkylammonium based ionic liquids was synthesized, and characterized. The length of the alkyl chain was systematically varied, and all compounds were synthesized with and without hydroxyl group, as well as formate and bis(triflyl)amide salts, aiming at getting insight into the influence of the different structure parts on the respective ionic liquid's properties.

  2. Applications of functionalized ionic liquids

    Institute of Scientific and Technical Information of China (English)

    LI Xuehui; ZHAO Dongbin; FEI Zhaofu; WANG Lefu

    2006-01-01

    Recent developments of the synthesis and applications of functionalized ionic liquids(including dual-functionalized ionic liquids) have been highlighted in this review. Ionic liquids are attracting attention as alternative solvents in green chemistry, but as more functionalized ILs are prepared, a greater number of applications in increasingly diverse fields are found.

  3. Radiation chemistry of ionic liquids

    International Nuclear Information System (INIS)

    Ionic liquids are expected as a replacement of processing media for the nuclear fuel cycle. Therefore, an understanding of the interactions of ionizing radiations and photons with ionic liquids is strongly needed. However, the radiation chemistry of ionic liquids is still a relatively unexplored topic although there has been a significant increase in the number of researchers in the field recently. (author)

  4. Ionic and Molecular Liquids

    DEFF Research Database (Denmark)

    Chaban, Vitaly V.; Prezhdo, Oleg

    2013-01-01

    Because of their outstanding versatility, room-temperature ionic liquids (RTILs) are utilized in an ever increasing number of novel and fascinating applications, making them the Holy Grail of modern materials science. In this Perspective, we address the fundamental research and prospective...

  5. Ionic smoke detectors

    CERN Document Server

    2002-01-01

    Ionic smoke detectors are products incorporating radioactive material. This article summarises the process for their commercialization and marketing, and how the activity is controlled, according to regulations establishing strict design and production requisites to guarantee the absence of radiological risk associated both with their use and their final handling as conventional waste. (Author)

  6. Understanding SO2 Capture by Ionic Liquids.

    Science.gov (United States)

    Mondal, Anirban; Balasubramanian, Sundaram

    2016-05-19

    Ionic liquids have generated interest for efficient SO2 absorption due to their low vapor pressure and versatility. In this work, a systematic investigation of the structure, thermodynamics, and dynamics of SO2 absorption by ionic liquids has been carried out through quantum chemical calculations and molecular dynamics (MD) simulations. MP2 level calculations of several ion pairs complexed with SO2 reveal its preferential interaction with the anion. Results of condensed phase MD simulations of SO2-IL mixtures manifested the essential role of both cations and anions in the solvation of SO2, where the solute is surrounded by the "cage" formed by the cations (primarily its alkyl tail) through dispersion interactions. These structural effects of gas absorption are substantiated by calculated Gibbs free energy of solvation; the dissolution is demonstrated to be enthalpy driven. The entropic loss of SO2 absorption in ionic liquids with a larger anion such as [NTf2](-) has been quantified and has been attributed to the conformational restriction of the anion imposed by its interaction with SO2. SO2 loading IL decreases its shear viscosity and enhances the electrical conductivity. This systematic study provides a molecular level understanding which can aid the design of task-specific ILs as electrolytes for efficient SO2 absorption. PMID:27119562

  7. Relativistic Multichannel Treatment of Ionic Rydberg States of Lanthanum

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-Feng; JIA Feng-Dong; ZHONG Zhi-Ping; XUE Ping; XU Xiang-Yuan; YAN Jun

    2007-01-01

    Ionic Rydberg energy levels of lanthanum are calculated from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory. The present calculated results are in better agreement with the experimental measurements than the previous calculations [J. Phys. B 34 (2001)369] due to the consideration of dynamical polarizations. Moreover, in the experimental spectra achieved by a five-laser resonance excitation via the intermediate state 5d6d3 F2, a series of weak ionic Rydberg states and some of perturbing states are found and assigned in this work.

  8. Nanoscale Ionic Materials

    KAUST Repository

    Rodriguez, Robert

    2008-11-18

    Polymer nanocomposites (nanoparticles dispersed in a polymer matrix) have been the subject of intense research for almost two decades in both academic and industrial settings. This interest has been fueled by the ability of nanocomposites to not only improve the performance of polymers, but also by their ability to introduce new properties. Yet, there are still challenges that polymer nanocomposites must overcome to reach their full potential. In this Research News article we discuss a new class of hybrids termed nanoparticle ionic materials (NIMS). NIMS are organic-inorganic hybrid materials comprising a nanoparticle core functionalized with a covalently tethered ionic corona. They are facilely engineered to display flow properties that span the range from glassy solids to free flowing liquids. These new systems have unique properties that can overcome some of the challenges facing nanocomosite materials. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

  9. Multilayer Ionic Transducers

    OpenAIRE

    Akle, Barbar Jawad

    2003-01-01

    A transducer consisting of multiple layers of ionic polymer material is developed for applications in sensing, actuation, and control. The transducer consists of two to four individual layers each approximately 200 microns thick. The transducers are connected in parallel to minimize the electric field requirements for actuation. The tradeoff in deflection and force can be controlled by controlling the mechanical constraint at the interface. Packaging the transducer in an outer coating produce...

  10. Cyclic phosphonium ionic liquids

    Directory of Open Access Journals (Sweden)

    Sharon I. Lall-Ramnarine

    2014-01-01

    Full Text Available Ionic liquids (ILs incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonylamide ILs with aliphatic and aromatic pendant groups. In addition to the syntheses of these novel materials, we report on a comparison of their properties with their ammonium congeners. These exemplars are slightly less conductive and have slightly smaller self-diffusion coefficients than their cyclic ammonium congeners.

  11. Course on Ionic Channels

    CERN Document Server

    1986-01-01

    This book is based on a series of lectures for a course on ionic channels held in Santiago, Chile, on November 17-20, 1984. It is intended as a tutorial guide on the properties, function, modulation, and reconstitution of ionic channels, and it should be accessible to graduate students taking their first steps in this field. In the presentation there has been a deliberate emphasis on the spe­ cific methodologies used toward the understanding of the workings and function of channels. Thus, in the first section, we learn to "read" single­ channel records: how to interpret them in the theoretical frame of kinetic models, which information can be extracted from gating currents in re­ lation to the closing and opening processes, and how ion transport through an open channel can be explained in terms of fluctuating energy barriers. The importance of assessing unequivocally the origin and purity of mem­ brane preparations and the use of membrane vesicles and optical tech­ niques in the stUGY of ionic channels a...

  12. Development of a multi-species mass transport model for concrete with account to thermodynamic phase equilibriums

    DEFF Research Database (Denmark)

    Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn;

    2011-01-01

    ) theory alone, not involving chemical processes, have no real practical interest since the chemical action is very dominant for cement based materials. Coupled mass transport and chemical equilibrium models can be used to calculate the variation in pore solution and solid-phase composition when using...

  13. Simultaneous multi-species determination of trimethyllead, monomethylmercury and three butyltin compounds by species-specific isotope dilution GC-ICP-MS in biological samples.

    Science.gov (United States)

    Poperechna, Nataliya; Heumann, Klaus G

    2005-09-01

    An accurate and sensitive multi-species species-specific isotope dilution GC-ICP-MS method was developed for the simultaneous determination of trimethyllead (Me3Pb+), monomethylmercury (MeHg+) and the three butyltin species Bu3Sn+, Bu2Sn2+, and BuSn3+ in biological samples. The method was validated by three biological reference materials (CRM 477, mussel tissue certified for butyltins; CRM 463, tuna fish certified for MeHg+; DORM 2, dogfish muscle certified for MeHg+). Under certain conditions, and with minor modifications of the sample pretreatment procedure, this method could also be transferred to environmental samples such as sediments, as demonstrated by analyzing sediment reference material BCR 646 (freshwater sediment, certified for butyltins). The detection limits of the multi-species GC-ICP-IDMS method for biological samples were 1.4 ng g(-1) for MeHg+, 0.06 ng g(-1) for Me3Pb+, 0.3 ng g(-1) for BuSn3+ and Bu3Sn+, and 1.2 ng g(-1) for Bu2Sn2+. Because of the high relevance of these heavy metal alkyl species to the quality assurance of seafood, the method was also applied to corresponding samples purchased from a supermarket. The methylated lead fraction in these samples, correlated to total lead, varied over a broad range (from 0.01% to 7.6%). On the other hand, the MeHg+ fraction was much higher, normally in the range of 80-100%. Considering that we may expect tighter legislative limitations on MeHg+ levels in seafood in the future, we found the highest methylmercury contents (up to 10.6 microg g(-1)) in two shark samples, an animal which is at the end of the marine food chain, whereas MeHg+ contents of less than 0.2 microg g(-1) were found in most other seafood samples; these results correlate with the idea that MeHg+ is usually of biological origin in the marine environment. The concentration of butyltins and the fraction of the total tin content that is from butyltins strongly depend on possible contamination, due to the exclusively anthropogenic

  14. IONIC LIQUIDS: PREPARATIONS AND LIMITATIONS

    OpenAIRE

    Dzulkefly Kuang Abdullah; Ahmad Adlie Shamsuri

    2010-01-01

    Ionic liquids are considered as an ideal alternative to volatile organic solvents and chemical industries in the future,because they are non-volatile. Ionic liquids are also considered as new novel chemical agents and widely regarded as agreener alternative to many commonly used solvents. Ionic liquids have been studied for a wide range of syntheticapplications and have attracted considerable interest for use as electrolytes in the areas of organic synthesis, catalysis,solar cell, fuel cells,...

  15. Electrochemical aspects of ionic liquids

    CERN Document Server

    Ohno, Hiroyuki

    2011-01-01

    The second edition is based on the original book, which has been revised, updated and expanded in order to cover the latest information on this rapidly growing field. The book begins with a description of general and electrochemical properties of ionic liquids and continues with a discussion of applications in biochemistry, ionic devices, functional design and polymeric ionic liquids. The new edition includes new chapters on Li ion Batteries and Actuators, as well as a revision of existing chapters to include a discussion on purification and the effects of impurities, adsorption of ionic liqui

  16. On the theory of electromagnetic waves and instabilities in multi-species weakly ionized plasmas in external d.c. electric field

    International Nuclear Information System (INIS)

    Electromagnetic modes with the electric vector of the wave lying in the plane defined by the wave vector and the external d.c. electric field are studied theoretically in weakly ionized plasmas with several sorts of ions. The corresponding instability criteria are also given. The analysis is based on kinetic equations with BGK model collision integrals for the one-particle distribution functions of the charged constituents (electrons and all sorts of ions). The linear theory of perturbation is applied. Special attention is given to the long-wave domain (modal wavelengths much larger than the electron mean free path): it is in this domain that the instabilities are found to set in first as the electron drift is gradually increased. The analysis of the instabilities is completed by a brief description of two (sometimes three) branches of ion acoustic instability, specific for the multi-species plasmas and propagating strictly along the direction of the external electric field. (author)

  17. Use of a multi-species reactive transport model to simulate chloride ingress in mortar exposed to NaCl solution or sea-water

    DEFF Research Database (Denmark)

    Jensen, Mads Mønster; De Weerdt, K.; Johannesson, Björn;

    2015-01-01

    Simulations of ion ingress in Portland cement mortar using a multi-species reactive mass transport model are compared with experimental test results. The model is an extended version of the Poisson–Nernst–Planck equations, accounting for chemical equilibrium. Saturated mortar samples were exposed...... reactive mass transport model is shown by comparing the simulation and experimental results. The tortuosity factor used in the simulations is adjusted to obtain the best reproduction of the experimental results. The model predicts the total chloride content satisfactorily, despite assumptions in the...... simulation like fixed hydration degree over time. Improvements and suggestions for further development of the model are discussed, e.g. extended hydration description, improved overall chemical description and a more strict use of the tortuosity factor....

  18. Characterisation of deuterium spectra from laser driven multi-species sources by employing differentially filtered image plate detectors in Thomson spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Alejo, A.; Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Doria, D.; Green, A.; Jung, D.; Lewis, C. L. S.; Nersisyan, G. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Krygier, A. G.; Freeman, R. R. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Clarke, R.; Green, J. S.; Notley, M. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Fernandez, J. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Instituto de Fusión Nuclear, Universidad Politécnica de Madrid, 28006 Madrid (Spain); Fuchs, J. [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Kleinschmidt, A.; Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstrasse 9, D-64289 Darmstadt (Germany); Morrison, J. T. [Propulsion Systems Directorate, Air Force Research Lab, Wright Patterson Air Force Base, Ohio 45433 (United States); Najmudin, Z.; Nakamura, H. [Blackett Laboratory, Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); and others

    2014-09-15

    A novel method for characterising the full spectrum of deuteron ions emitted by laser driven multi-species ion sources is discussed. The procedure is based on using differential filtering over the detector of a Thompson parabola ion spectrometer, which enables discrimination of deuterium ions from heavier ion species with the same charge-to-mass ratio (such as C{sup 6+}, O{sup 8+}, etc.). Commonly used Fuji Image plates were used as detectors in the spectrometer, whose absolute response to deuterium ions over a wide range of energies was calibrated by using slotted CR-39 nuclear track detectors. A typical deuterium ion spectrum diagnosed in a recent experimental campaign is presented, which was produced from a thin deuterated plastic foil target irradiated by a high power laser.

  19. Use of multi species freshwater bio monitor (MFB) to assess behavioral changes of guppy Poecilia reticulata and freshwater prawn Macrobrachium lanchesteri in response to cadmium

    International Nuclear Information System (INIS)

    The Multi species Freshwater Bio monitor (MFB) uses the measurement and analysis of different types of behaviours from different aquatic organisms for monitoring the water quality in freshwater ecosystem. The aim of this study was to determine the specific response of freshwater shrimp (Macrobrachium lanchesteri) and guppy fish (Poecilia reticulata) to cadmium (Cd) in the laboratory. Different concentrations of Cd were exposed to M. lanchesteri (1 ppb and 10 ppb) and P. reticulata (100 ppb and 560 ppb) and the behavioural changes of the organisms were recorded by MFB for 2 hours. Results showed that the behavioural and ventilation response of M. lanchesteri and P. reticulata increased with increasing exposure concentrations of Cd. Results also showed that the shrimp was more sensitive to Cd than the guppy fish and these local species were suitable as indicator organism for the MFB. (author)

  20. Ionic liquids, electrolyte solutions including the ionic liquids, and energy storage devices including the ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gering, Kevin L.; Harrup, Mason K.; Rollins, Harry W.

    2015-12-08

    An ionic liquid including a phosphazene compound that has a plurality of phosphorus-nitrogen units and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. One pendant group of the at least one pendant group comprises a positively charged pendant group. Additional embodiments of ionic liquids are disclosed, as are electrolyte solutions and energy storage devices including the embodiments of the ionic liquid.

  1. Periodicity and map for discovery of new ionic liquids

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Suojiang

    2006-01-01

    [1]Trohalaki,S.,Pachter,R.,Drake,G.W.,Hawkins,T.,Quantitative structure-property relationships for melting points and densities of ionic liquids,Energy & Fuels,2005,19:279-284.[2]Holbery,J.D.,Seddon,K.R.,The phase behavior of 1-alkyl-3-methylimidazolium tetrafluoroborates,ionic liquids and ionic liquid crystals,J.Chem.Soc.Dalton Trans.,1999,13:2133-2139.[3]Katritzky,A.R.,Lomaka,A.,Petrukhin,R.et al.,QSPR correlation of the melting point for pyridinium bromides,potential ionic liquids,J.Chem.Inf.Comput.Sci.,2002,42:71-74.[4]Katritzky,A.R.,Jain,R.,Lomaka,A.et al.,Correlation of the melting points of potential ionic liquids (imidazolium bromides and benzimidazolium bromides) using the CODESSA program,J.Chem.Inf.Comput.Sci.,2002,42:225-231.[5]Eike,D.M.,Brennecke,J.F.,Maginn,E.J.,Predicting melting points of quaternary ammonium ionic liquids,Green Chemistry,2003,5:323-328.[6]Dupont,J.,Souza,R.F.,Suarez,A.Z.,Ionic liquid (molten salt) phase organometallic catalysis,J.Chem.Rev.,2002,102:3667-3692.[7]Turner,E.A.,Pye,C.C.,Singer,R.D.,Use of ab initio calculations toward the rational design of room temperature ionic liquids,J.Phys.Chem.A,2003,107(13):2277-2288.[8]Morrow,T.I.,Maginn,E.J.,Molecular dynamics study of the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate,J.Phys.Chem.B,2002,106:12807-12813.[9]Cadena,C.,Antony,J.L.,Shah,J.K.et al.,Why is CO2 so soluble in imidazolium-based ionic liquids? J.Am.Chem.Soc.,2004,126(16):5300-5308.[10]Liu,Z.,Huang,S.,Wang,W.,A refined force field for molecular simulation of imidazolium-based ionic liquids,J.Phys.Chem.B,2004,108(34):12978-12989.[11]Earle,M.J,Seddon,K.R.,Ionic liquids,green solvents for the future,Pure Appl.Chem.,2000,72(7):1391-1398.[12]Mendeleev on periodicity:I and II,http://www.rod.beavon.clara.net/periodic1.htm[13]Hoffmann,R.,Building bridges between inorganic and organic chemistry,Angew.Chem.Int.Ed.Engl.,1982,21(10):711-800.

  2. Osmotic Pressure in Ionic Microgel Dispersions

    Science.gov (United States)

    Denton, Alan R.; Tang, Qiyun

    2015-03-01

    Microgels are microscopic gel particles, typically 10-1000 nm in size, that are swollen by a solvent. Hollow microgels (microcapsules) can encapsulate cargo, such as dye molecules or drugs, in their solvent-filled cavities. Their sensitive response to environmental conditions (e.g., temperature, pH) and influence on flow properties suit microgels to widespread applications in the chemical, pharmaceutical, food, and consumer care industries. When dispersed in water, polyelectrolyte gels become charged through dissociation of counterions. The electrostatic contribution to the osmotic pressure inside and outside of ionic microgels influences particle swelling and bulk materials properties, including thermodynamic, structural, optical, and rheological properties. Within the primitive and cell models of polyelectrolyte solutions, we derive an exact statistical mechanical formula for the contribution of mobile microions to the osmotic pressure within ionic microgels. Using Poisson-Boltzmann theory, we validate this result by explicitly calculating ion distributions across the surface of an ionic microgel and the electrostatic contribution to the osmotic pressure. Within a coarse-grained one-component model, we further chart the limits of the cell model for salty dispersions. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

  3. Substantial Underestimation of Post-Harvest Burning Emissions in the North China Plain Revealed by Multi-Species Space Observations.

    Science.gov (United States)

    Stavrakou, T; Müller, J-F; Bauwens, M; De Smedt, I; Lerot, C; Van Roozendael, M; Coheur, P-F; Clerbaux, C; Boersma, K F; van der A, R; Song, Y

    2016-01-01

    The large-scale burning of crop residues in the North China Plain (NCP), one of the most densely populated world regions, was recently recognized to cause severe air pollution and harmful health effects. A reliable quantification of the magnitude of these fires is needed to assess regional air quality. Here, we use an eight-year record (2005-2012) of formaldehyde measurements from space to constrain the emissions of volatile organic compounds (VOCs) in this region. Using inverse modelling, we derive that satellite-based post-harvest burning fluxes are, on average, at least a factor of 2 higher than state-of-the-art bottom-up statistical estimates, although with significant interannual variability. Crop burning is calculated to cause important increases in surface ozone (+7%) and fine aerosol concentrations (+18%) in the North China Plain in June. The impact of crop fires is also found in satellite observations of other species, glyoxal, nitrogen dioxide and methanol, and we show that those measurements validate the magnitude of the top-down fluxes. Our study indicates that the top-down crop burning fluxes of VOCs in June exceed by almost a factor of 2 the combined emissions from other anthropogenic activities in this region, underscoring the need for targeted actions towards changes in agricultural management practices. PMID:27577535

  4. Wettability by Ionic Liquids.

    Science.gov (United States)

    Liu, Hongliang; Jiang, Lei

    2016-01-01

    Ionic liquids (ILs) have become particularly attractive recently because they have demonstrated themselves to be important construction units in the broad fields of chemistry and materials science, from catalysis and synthesis to analysis and electrochemistry, from functional fluids to clean energy, from nanotechnology to functional materials. One of the greatest issues that determines the performance of ILs is the wettability of correlated surfaces. In this concept article, the key developments and issues in IL wettability are surveyed, including the electrowetting of ILs in gas-liquid-solid systems and liquid-liquid-solid systems, ILs as useful probe fluids, the superwettability of Ils, and future directions in IL wettability. This should generate extensive interest in the field and encourage more scientists to engage in this area to tackle its scientific challenges. PMID:26619157

  5. Predictive model for ionic liquid extraction solvents for rare earth elements

    International Nuclear Information System (INIS)

    The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF3-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effective extraction solvents for liquid-liquid extraction of DyF3 were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests

  6. Synthesis and characterization of new class of ionic liquids containing phenolate anion

    International Nuclear Information System (INIS)

    In these manuscript novel ionic liquids containing a new class of 'phenolate' anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using 1H NMR and 13C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated

  7. Predictive model for ionic liquid extraction solvents for rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Grabda, Mariusz; Oleszek, Sylwia [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2,1-Katahira, 2-Chome, 980-8577 Sendai (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, ul. M. Sklodowskiej-Curie 34, 41-819, Zabrze (Poland); Panigrahi, Mrutyunjay; Kozak, Dmytro; Shibata, Etsuro; Nakamura, Takashi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2,1-Katahira, 2-Chome, 980-8577 Sendai (Japan); Eckert, Franck [COSMOlogic GmbH & Co KG, Imbacher Weg 46, 50379 Leverkusen (Germany)

    2015-12-31

    The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF{sub 3}-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effective extraction solvents for liquid-liquid extraction of DyF{sub 3} were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests.

  8. Predictive model for ionic liquid extraction solvents for rare earth elements

    Science.gov (United States)

    Grabda, Mariusz; Oleszek, Sylwia; Panigrahi, Mrutyunjay; Kozak, Dmytro; Eckert, Franck; Shibata, Etsuro; Nakamura, Takashi

    2015-12-01

    The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF3-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids' ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effective extraction solvents for liquid-liquid extraction of DyF3 were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests.

  9. Synthesis and characterization of new class of ionic liquids containing phenolate anion

    Energy Technology Data Exchange (ETDEWEB)

    Lethesh, Kallidanthiyil Chellappan, E-mail: lethesh.chellappan@petronas.com.my [PETRONAS Ionic Liquids Center, Universiti Teknologi PETRONAS (Malaysia); Wilfred, Cecilia Devi; Taha, M. F. [Department of Chemical Engineering, Universiti Teknologi PETRONAS (Malaysia); Thanabalan, M. [Fundamental and Applied Sciences, Universiti Teknologi PETRONAS (Malaysia)

    2014-10-24

    In these manuscript novel ionic liquids containing a new class of 'phenolate' anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using {sup 1}H NMR and {sup 13}C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated.

  10. Simultaneous multi-species determination of trimethyllead, monomethylmercury and three butyltin compounds by species-specific isotope dilution GC-ICP-MS in biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Poperechna, Nataliya; Heumann, Klaus G. [Johannes Gutenberg-University Mainz (Germany). Institute of Inorganic Chemistry and Analytical Chemistry

    2005-09-01

    An accurate and sensitive multi-species species-specific isotope dilution GC-ICP-MS method was developed for the simultaneous determination of trimethyllead (Me{sub 3}Pb{sup +}), monomethylmercury (MeHg{sup +}) and the three butyltin species Bu{sub 3}Sn{sup +}, Bu{sub 2}Sn{sup 2+}, and BuSn{sup 3+} in biological samples. The method was validated by three biological reference materials (CRM 477, mussel tissue certified for butyltins; CRM 463, tuna fish certified for MeHg{sup +}; DORM 2, dogfish muscle certified for MeHg{sup +}). Under certain conditions, and with minor modifications of the sample pretreatment procedure, this method could also be transferred to environmental samples such as sediments, as demonstrated by analyzing sediment reference material BCR 646 (freshwater sediment, certified for butyltins). The detection limits of the multi-species GC-ICP-IDMS method for biological samples were 1.4 ng g{sup -1} for MeHg{sup +}, 0.06 ng g{sup -1} for Me{sub 3}Pb{sup +}, 0.3 ng g{sup -1} for BuSn{sup 3+} and Bu{sub 3}Sn{sup +}, and 1.2 ng g{sup -1} for Bu{sub 2}Sn{sup 2+}. Because of the high relevance of these heavy metal alkyl species to the quality assurance of seafood, the method was also applied to corresponding samples purchased from a supermarket. The methylated lead fraction in these samples, correlated to total lead, varied over a broad range (from 0.01% to 7.6%). On the other hand, the MeHg{sup +} fraction was much higher, normally in the range of 80-100%. Considering that we may expect tighter legislative limitations on MeHg{sup +} levels in seafood in the future, we found the highest methylmercury contents (up to 10.6 {mu}g g{sup -1}) in two shark samples, an animal which is at the end of the marine food chain, whereas MeHg{sup +} contents of less than 0.2 {mu}g g{sup -1} were found in most other seafood samples; these results correlate with the idea that MeHg{sup +} is usually of biological origin in the marine environment. The concentration of

  11. Ionic motion in crystalline cryolite.

    Science.gov (United States)

    Foy, Lindsay; Madden, Paul A

    2006-08-10

    The character of the ion dynamics in crystalline cryolite, Na(3)AlF(6), a model double perovskite-structured mineral, has been examined in computer simulations using a polarizable ionic potential obtained by force-fitting to ab initio electronic structure calculations. NMR studies, and conductivity measurements, have indicated a high degree of mobility, in both Na(+) ion diffusion and reorientation of the AlF(6) octahedral units. The simulations reproduce the low-temperature (tilted) crystal structure and the existence of a transition to a cubic structure at elevated temperatures, in agreement with diffraction measurements, though the calculated transition temperature is too low. The reorientational dynamics of the AlF(6) octahedra is shown to consist of a hopping motion between the various tilted positions of the low-temperature form, even above the transition temperature. The rate of reorientation estimated by extrapolation to the temperature régime of the NMR measurements is consistent with the experimental data. In addition, we report a novel cooperative "tilt-swapping" motion of the differently tilted sublattices, just below the transition temperature. The perfect crystals show no Na(+) diffusion, in apparent disagreement with observation. We argue, following previous analyses of the cryolite phase diagram, that the diffusion observed in the experimental studies is a consequence of defects that are intrinsic to the thermodynamically stable form of cryolite. By introducing defects into the simulation cell, we obtain diffusion rates that are consistent with the NMR and conductivity measurements. Finally, we demonstrate a link between diffusion of the Na(+) ions and the reorientation of AlF(6) units, though the correlation between the two is not very strong. PMID:16884249

  12. Including cetaceans in multi-species assessment models using strandings data: why, how and what can we do about it?

    Directory of Open Access Journals (Sweden)

    Camilo Saavedra

    2014-07-01

    due to lack of good information because, unlike the case of commercial fish stocks, usually there are no timeseries of abundance estimates available and the biological information available has been derived from the examination of stranded and/or bycatch individuals which could generate biased estimates. Common dolphin is the more abundant species of small cetacean in the Atlantic coast of the Iberian Peninsula and for which more biological information is available. For this reason, we have used this species as an example to explain our approach to obtain estimates of all the biological parameters needed to build a cetacean population model from strandings data. Southern European hake stock is distributed from Gulf of Biscay to Strait of Gibraltar, along Atlantic coast of the Iberian Peninsula, and thus the common dolphin population we will try to model is the one which lies in this area, although it is considered that there is a single common dolphin population is continuous throughout the European Atlantic coast (Natoli, 2008. Due to their protected status, no timeseries of catches neither fishing biological samples exist in the area, in contrast as in commercial fish species. Therefore, the major source of biological information is derived from strandings, mainly collected by experienced personnel from the “Coordinadora para o Estudio dos Mamíferos Mariños” (CEMMA operating in Galicia (Northwest of Spain since 1990. From these data we have derived the direct and indirect information required for our model. However, only the following parameters: maximum and minimum dolphin length and weight, sex-ratio and proportion of dead dolphins exhibiting bycatch signs can be used without further data processing. From these parameters, the length-weight relationship can also be easily calculated for both males and females, in our case, by fitting a logarithmic regression. Nonetheless, to fit a growth curve is necessary to know the age of each stranded dolphin and

  13. Genetic Algorithm with Dynamic Regional Multi-Species%动态区域性多群体搜索的遗传算法

    Institute of Scientific and Technical Information of China (English)

    黎明; 杨小芹; 周琳霞

    2003-01-01

    提出了一种新的动态区域性多群体搜索的遗传算法.该方法的各个遗传群体所占据的搜索空间由自适应模糊Hamming神经网络的决定,此神经网络通过对遗传个体分类和学习,将不同的遗传群体分配在搜索空间的不同位置,并可以动态地调整遗传群体的搜索区域或建立新的遗传群体,从而确保了遗传群体的个体多样性,有效地抑制了可能发生的早熟收敛现象,而且使得遗传算法具有较强的全局寻优能力和快速局部寻优能力.本文的实验通过对典型的复杂多模函数的优化计算,也显示了动态区域性多群体搜索的遗传算法的优良性能.%A novel genetic algorithm with dynamic regional multi-species is proposed in this paper. Each of those genetic species occupies a dynamic region that is determined by the weight vector of a fuzzy adaptive Hamming neural network. Through learning and classification of genetic individuals in the evolutionary procedure, the neural network distributes multi-species into different regions of the search space. Furthermore, the neural network dynamically expands each search region or establishes new region for good offspring individuals to continuously keep the diversification of genetic population. As a result, the premature problem inherent in genetic algorithms is alleviated and better tradeoff between the ability of exploration and exploitation can be obtained. The experimental results on the optimization computation of typical multi-modal functions also have shown good performance of the proposed genetic algorithm.

  14. Prediction of liquid−liquid equilibria of (aromatic + aliphatic + ionic liquid) systems using the Cosmo-SAC model

    International Nuclear Information System (INIS)

    Highlights: ► Aromatic/aliphatic hydrocarbons separation by ionic liquids. ► Cosmo-SAC thermodynamic model for prediction of LLE by quantum chemical calculations. ► Predictions successful for some ionic liquids. ► Correlation by single parameter for other ionic liquids. ► Preliminary screening of additional ionic liquids for aromatic/aliphatic separation. - Abstract: The extraction of aromatic hydrocarbons from aliphatic hydrocarbons is an important problem. This process can be used to enhance the capacity of ethylene crackers by prior removal of aromatics that cannot be cracked. Ionic liquids have been investigated extensively for liquid–liquid extraction of aromatics from aliphatics. The choice of a suitable ionic liquid may be made by measuring liquid−liquid equilibria. However, the large number of ionic liquids, formed by the various cation and anion combinations, makes the experimental measurements expensive and time consuming. Hence, a predictive thermodynamic model called Cosmo-SAC that uses quantum chemical calculations for calculating liquid−liquid equilibria has been evaluated. A priori predictions are accurate for some ionic liquids and inaccurate for some ionic liquids. However, it has been shown that even when a priori predictions are inaccurate, the data can be correlated using a single parameter that is characteristic of the ionic liquid and accurate predictions can be made for additional aromatic/aliphatic combinations for the same ionic liquid. A comparison with the NRTL and UNIQUAC models has also been carried out. In addition, a preliminary screening of ionic liquids for aromatic/aliphatic separations has been carried out using the Cosmo-SAC model. Finally, the “Cosmo” files for eight cations and sixteen anions corresponding to 128 potential ionic liquids have been provided for the use of the general scientific community to predict any thermodynamic equilibria involving ionic liquids without the use of any molecular modeling

  15. Toward an ecosystem approach to fisheries in the Mediterranean Sea: Multi-gear/multi-species implications from an ecosystem model of the Greek Ionian Sea

    Science.gov (United States)

    Moutopoulos, Dimitrios K.; Libralato, Simone; Solidoro, Cosimo; Stergiou, Konstantinos I.

    2013-03-01

    A mass-balance food web model was developed for the Greek Ionian Sea ecosystem, including 39 functional groups and 6 fisheries at depths between 50 and 1100 m during the 1990s. The study area is among the most oligotrophic in the Mediterranean, having a complex food web structure, high numbers of energy pathways, trophic levels and functional groups and high rates of matter cycling, all of which are indicative of a mature system. To separate the effects of discards and landings, analyses and indicators were estimated through two models with the same parameterization: one included all catches and the other only landings. The primary production required to sustain the fisheries was low, and approximately half of it was used for sustaining by-catches and discards. Discards have greater impacts than landings on the flows and energy necessary to support the fisheries. Although fishing mortality by each gear type was moderate, the cumulative fishing impact estimated from all gears combined exceeded safe limits, thus enhancing the benefits of moving toward a multi-gear/multi-species approach to fisheries. This study is a first step toward quantifying discards in a multispecies/multigear system and considering the uncertainties in quantifying discard quantities, especially for low trophic levels.

  16. Molecular analysis of endocrine disruption in hornyhead turbot at wastewater outfalls in southern california using a second generation multi-species microarray.

    Directory of Open Access Journals (Sweden)

    Michael E Baker

    Full Text Available Sentinel fish hornyhead turbot (Pleuronichthysverticalis captured near wastewater outfalls are used for monitoring exposure to industrial and agricultural chemicals of ~ 20 million people living in coastal Southern California. Although analyses of hormones in blood and organ morphology and histology are useful for assessing contaminant exposure, there is a need for quantitative and sensitive molecular measurements, since contaminants of emerging concern are known to produce subtle effects. We developed a second generation multi-species microarray with expanded content and sensitivity to investigate endocrine disruption in turbot captured near wastewater outfalls in San Diego, Orange County and Los Angeles California. Analysis of expression of genes involved in hormone [e.g., estrogen, androgen, thyroid] responses and xenobiotic metabolism in turbot livers was correlated with a series of phenotypic end points. Molecular analyses of turbot livers uncovered altered expression of vitellogenin and zona pellucida protein, indicating exposure to one or more estrogenic chemicals, as well as, alterations in cytochrome P450 (CYP 1A, CYP3A and glutathione S-transferase-α indicating induction of the detoxification response. Molecular responses indicative of exposure to endocrine disruptors were observed in field-caught hornyhead turbot captured in Southern California demonstrating the utility of molecular methods for monitoring environmental chemicals in wastewater outfalls. Moreover, this approach can be adapted to monitor other sites for contaminants of emerging concern in other fish species for which there are few available gene sequences.

  17. A Parallel 3D Model for The Multi-Species Low Energy Beam Transport System of the RIA Prototype ECR Ion Source Venus

    International Nuclear Information System (INIS)

    The driver linac of the proposed Rare Isotope Accelerator (RIA) requires a great variety of high intensity, high charge state ion beams. In order to design and to optimize the low energy beamline optics of the RIA front end,we have developed a new parallel three-dimensional model to simulate the low energy, multi-species ion beam formation and transport from the ECR ion source extraction region to the focal plane of the analyzing magnet. A multisection overlapped computational domain has been used to break the original transport system into a number of each subsystem, macro-particle tracking is used to obtain the charge density distribution in this subdomain. The three-dimensional Poisson equation is solved within the subdomain and particle tracking is repeated until the solution converges. Two new Poisson solvers based on a combination of the spectral method and the multigrid method have been developed to solve the Poisson equation in cylindrical coordinates for the beam extraction region and in the Frenet-Serret coordinates for the bending magnet region. Some test examples and initial applications will also be presented

  18. Using Multi-Species Foraminiferal δ18O to Reconstruct Hydrologic Changes in the Gulf of Panama From LGM to Present

    Science.gov (United States)

    Benway, H. M.; Mix, A. C.

    2002-12-01

    Currently, an excess in precipitation minus evaporation (P-E) maintains a low-salinity surface layer and a shallow pycnocline in the Gulf of Panama. In contrast, the Caribbean has high salinity due to high evaporation relative to precipitation. The strong salinity gradient between these two regions is sustained by northeasterly trade winds, which carry evaporated moisture from the Caribbean over the Panama Isthmus and into the Gulf of Panama, where high SSTs attract the moisture-laden air masses. This leads to atmospheric convection and heavy rainfall on the Pacific side of the Isthmus in the Gulf of Panama. Since the majority of the rainfall in this region originates as water vapor in the Caribbean, changes in vapor transport can be estimated by changes in upper ocean structure in the Gulf of Panama. A multi-species approach is used in a Panama Basin sediment core to reconstruct changes in cross-isthmus vapor transport from LGM to present. We measure δ18O in two species of planktonic foraminifera, one that lives at the surface and one that lives at the base of the pycnocline, in order to estimate the isotopic contrast across the pycnocline, which is directly related to net precipitation in the Gulf of Panama (i.e., an increase in δ18O contrast between the sea surface and the base of the pycnocline is associated with an increase in P-E).

  19. Special Report: Solid Ionic Conductors.

    Science.gov (United States)

    Shriver, Duward F.; Farrington, Gregory C.

    1985-01-01

    Solid ionic conductors are unusual materials that may find valuable applications in devices ranging from high-energy density batteries to lasers. The nature of these materials and their potential uses are discussed. (JN)

  20. Novel approaches to ionic chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, P.K.

    1990-11-01

    Research during this reporting period, continued on ionic chromatography. Major progress has been made towards on-line on-demand generation of ultrapure chemicals by electrochemical means. The concentration of the generated material is governed electrochemically.

  1. Studies in solid state ionics

    International Nuclear Information System (INIS)

    Studies performed over 10 years by the high temperature chemistry group are reviewed. Attention was paid to different aspects of ionic solids from the point of view of practical as well as theoretical needs of nuclear technology. Thus ceramic fuel compound like uranates, urania-thoria system, solid electrolytes based on oxides and ionics transformations were studied under reactor irradiation. (author) 13 figs., 3 tabs., 46 refs

  2. Ionic Liquid Epoxy Resin Monomers

    Science.gov (United States)

    Paley, Mark S. (Inventor)

    2013-01-01

    Ionic liquid epoxide monomers capable of reacting with cross-linking agents to form polymers with high tensile and adhesive strengths. Ionic liquid epoxide monomers comprising at least one bis(glycidyl) N-substituted nitrogen heterocyclic cation are made from nitrogen heterocycles corresponding to the bis(glycidyl) N-substituted nitrogen heterocyclic cations by a method involving a non-nucleophilic anion, an alkali metal cation, epichlorohydrin, and a strong base.

  3. Electrochemical Depositions in Ionic Liquids

    OpenAIRE

    De Vreese, Peter

    2013-01-01

    In this PhD thesis, several aspects of the electrodeposition of metals and alloys in ionic liquids were investigated. First, the deposition of brass from choline acetate was studied. Secondly, the electrodeposition of pure molybdenum from ionic liquids based on phosphonium chloride and zinc chloride was treated. In each case, the influence of water, either as a main constituent of the electrolyte or an impurity, was investigated. When comparing electrochemical processes such as electrodeposit...

  4. Ionic liquids within polymer matrices

    Czech Academy of Sciences Publication Activity Database

    Matějka, Libor; Donato, Ricardo Keitel; Schrekker, H. S.

    Gargnano, Lago di Garda : European Polymer Federation, 2013. s. 10. [EUPOC 2013 on Polymers & Ionic Liquids. 01.09.2013-05.09.2013, Gargnano, Lago di Garda] R&D Projects: GA ČR GAP108/12/1459 Grant ostatní: AV ČR(CZ) M200501203 Institutional support: RVO:61389013 Keywords : ionic liquids * nanocomposite * epoxide Subject RIV: CD - Macromolecular Chemistry

  5. Hydrophobic ionic liquids

    Science.gov (United States)

    Koch, Victor R.; Nanjundiah, Chenniah; Carlin, Richard T.

    1998-01-01

    Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F--, Cl--, CF.sub.3 --, SF.sub.5 --, CF.sub.3 S--, (CF.sub.3).sub.2 CHS-- or (CF.sub.3).sub.3 CS--; and X.sup.- is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 .ANG..sup.3.

  6. Local character of magnetic coupling in ionic solids

    OpenAIRE

    Moreira, Ibério de Pinho Ribeiro; Illas i Riera, Francesc; Calzado, C. J.; J.F. Sanz; Malrieu, J.P.; Ben Amor, N.; Maynau, D.

    1999-01-01

    Magnetic interactions in ionic solids are studied using parameter-free methods designed to provide accurate energy differences associated with quantum states defining the Heisenberg constant J. For a series of ionic solids including KNiF3, K2NiF4, KCuF3, K2CuF4, and high- Tc parent compound La2CuO4, the J experimental value is quantitatively reproduced. This result has fundamental implications because J values have been calculated from a finite cluster model whereas experiments refer to infin...

  7. A Nonlocal Poisson-Fermi Model for Ionic Solvent

    CERN Document Server

    Xie, Dexuan; Eisenberg, Bob; Scott, L Ridgway

    2016-01-01

    We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion size effects and polarization correlations among water molecules in the calculation of electrostatic potential. It includes the previous Poisson-Fermi models as special cases, and its solution is the convolution of a solution of the corresponding nonlocal Poisson dielectric model with a Yukawa-type kernel function. Moreover, the Fermi distribution is shown to be a set of optimal ionic concentration functions in the sense of minimizing an electrostatic potential free energy. Finally, numerical results are reported to show the difference between a Poisson-Fermi solution and a corresponding Poisson solution.

  8. On the free energy of ionic hydration

    CERN Document Server

    Hummer, G; García, A E; Hummer, Gerhard; Pratt, Lawrence R.; Garcia, Angel E.

    1995-01-01

    The hydration free energies of ions exhibit an approximately quadratic dependence on the ionic charge, as predicted by the Born model. We analyze this behavior using second-order perturbation theory. This provides effective methods to calculating free energies from equilibrium computer simulations. The average and the fluctuation of the electrostatic potential at charge sites appear as the first coefficients in a Taylor expansion of the free energy of charging. Combining the data from different charge states allows calculation of free-energy profiles as a function of the ionic charge. The first two Taylor coefficients of the free-energy profiles can be computed accurately from equi- librium simulations; but they are affected by a strong system-size dependence. We apply corrections for these finite-size effects by using Ewald lattice sum- mation and adding the self-interactions consistently. Results are presented for a model ion with methane-like Lennard-Jones parameters in SPC water. We find two very closely ...

  9. Task-specific ionic liquid for solubilizing metal oxides.

    Science.gov (United States)

    Nockemann, Peter; Thijs, Ben; Pittois, Stijn; Thoen, Jan; Glorieux, Christ; Van Hecke, Kristof; Van Meervelt, Luc; Kirchner, Barbara; Binnemans, Koen

    2006-10-26

    Protonated betaine bis(trifluoromethylsulfonyl)imide is an ionic liquid with the ability to dissolve large quantities of metal oxides. This metal-solubilizing power is selective. Soluble are oxides of the trivalent rare earths, uranium(VI) oxide, zinc(II) oxide, cadmium(II) oxide, mercury(II) oxide, nickel(II) oxide, copper(II) oxide, palladium(II) oxide, lead(II) oxide, manganese(II) oxide, and silver(I) oxide. Insoluble or very poorly soluble are iron(III), manganese(IV), and cobalt oxides, as well as aluminum oxide and silicon dioxide. The metals can be stripped from the ionic liquid by treatment of the ionic liquid with an acidic aqueous solution. After transfer of the metal ions to the aqueous phase, the ionic liquid can be recycled for reuse. Betainium bis(trifluoromethylsulfonyl)imide forms one phase with water at high temperatures, whereas phase separation occurs below 55.5 degrees C (temperature switch behavior). The mixtures of the ionic liquid with water also show a pH-dependent phase behavior: two phases occur at low pH, whereas one phase is present under neutral or alkaline conditions. The structures, the energetics, and the charge distribution of the betaine cation and the bis(trifluoromethylsulfonyl)imide anion, as well as the cation-anion pairs, were studied by density functional theory calculations. PMID:17048916

  10. Physicochemical properties of low viscous lactam based ionic liquids

    International Nuclear Information System (INIS)

    Graphical abstract: Remarkably low viscosities of butyrolactam acetate and caprolactam acetate: experimental values (symbols) and VTF equation fitting (solid lines). - Highlights: • Caprolactam and butyrolactam based novel six ionic liquids have been synthesized. • Density, viscosity and speed of sound of lactam based ionic liquids have been measured. • Remarkably low viscosity has been observed for studied lactum based ionic liquids. • Effects of alkyl chain length on anion, geometry of cation and temperature upon studied properties have been discussed. - Abstract: Lactam based ionic liquids were synthesized by an atom economization process between a lactam such as caprolactam or butyrolactam with a Brønsted acid such as formic acid, acetic acid or hexanoic acid. The density, speed of sound and viscosity were measured at atmospheric pressure and as a function of temperature from T = (293.15 to 333.15) K. The experimental density and viscosity values were fitted with linear and Vogel–Tamman–Fulcher (VTF) equations, respectively and found to be fitting well within the experimental error. Thermodynamically important derived properties such as the coefficient of thermal expansion (α) and isentropic compressibility (βs) were calculated from the experimental density and speed of sound values. Lattice potential energy (UPOT) has been calculated to understand the strength of ionic interaction between the ions and the standard entropy (So) has been estimated to assess the disorder within the fluids. The remarkably low values of viscosity of ionic liquids studied are discussed on the basis of activation energy estimated from the Arrhenius equation. Furthermore, the effect of alkyl chain length on the anion, geometry of the cation and temperature has been analysed for the properties studied

  11. On the formulation of species reaction rates in the context of multi-species CFD codes using complex chemistry tabulation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Michel, Jean-Baptiste; Colin, Olivier; Angelberger, Christian [IFP, 1 et 4 Avenue de Bois Preau, F-92500 Rueil Malmaison (France)

    2010-04-15

    In the standard implementation of tabulated combustion models of the FPI or FGM type, the mean species mass fractions are read from look-up tables as functions of a progress variable, mixture fraction and their variances. In multi-species CFD codes however, the mean thermodynamic properties are deduced from the local mean species mass fractions. The unclosed mean source terms appearing in the latter's transport equations must then be given by the chemistry look-up tables. Two possible formulations for this mean source terms are discussed and compared in the present paper. In the reaction rate (RR) formulation, all mean reaction rates are directly read from a look-up table. In the mass fraction (MF) formulation, only the reaction rate for the progress variable is stored, and mean species source terms are constructed to relax the mean mass fractions towards the value stored in the look-up table. After a detailed description of in particular the MF formulation, simple a priori tests of auto-igniting reactors without convection and diffusion are used to illustrate and discuss the differences between the two formulations. Both formulations are then applied to a RANS simulation of the Cabra et al. burner in the context of a PCM-FPI and of an ADF-PCM model. The reported findings confirm the conclusions from the simple tests, highlighting the definitive advantages of the MF formulation. It ensures an accurate reproduction of auto-ignition delays, species evolutions and equilibriums, at the condition that the relaxation parameter is of the order of a characteristic chemical time. Finally, it is shown that the relaxation's effect is only a second order correction. (author)

  12. Designing optimized multi-species monitoring networks to detect range shifts driven by climate change: a case study with bats in the North of Portugal.

    Directory of Open Access Journals (Sweden)

    Francisco Amorim

    Full Text Available Here we develop a framework to design multi-species monitoring networks using species distribution models and conservation planning tools to optimize the location of monitoring stations to detect potential range shifts driven by climate change. For this study, we focused on seven bat species in Northern Portugal (Western Europe. Maximum entropy modelling was used to predict the likely occurrence of those species under present and future climatic conditions. By comparing present and future predicted distributions, we identified areas where each species is likely to gain, lose or maintain suitable climatic space. We then used a decision support tool (the Marxan software to design three optimized monitoring networks considering: a changes in species likely occurrence, b species conservation status, and c level of volunteer commitment. For present climatic conditions, species distribution models revealed that areas suitable for most species occur in the north-eastern part of the region. However, areas predicted to become climatically suitable in the future shifted towards west. The three simulated monitoring networks, adaptable for an unpredictable volunteer commitment, included 28, 54 and 110 sampling locations respectively, distributed across the study area and covering the potential full range of conditions where species range shifts may occur. Our results show that our framework outperforms the traditional approach that only considers current species ranges, in allocating monitoring stations distributed across different categories of predicted shifts in species distributions. This study presents a straightforward framework to design monitoring schemes aimed specifically at testing hypotheses about where and when species ranges may shift with climatic changes, while also ensuring surveillance of general population trends.

  13. Multi-Season Regional Analysis of Multi-Species Occupancy: Implications for Bird Conservation in Agricultural Lands in East-Central Argentina.

    Directory of Open Access Journals (Sweden)

    Andrea Paula Goijman

    Full Text Available Rapid expansion and intensification of agriculture create challenges for the conservation of biodiversity and associated ecosystem services. In Argentina, the total row crop planted area has increased in recent decades with the expansion of soybean cultivation, homogenizing the landscape. In 2003 we started the first long-term, large-scale bird monitoring program in agroecosystems of central Argentina, in portions of the Pampas and Espinal ecoregions. Using data from this program, we evaluated the effect of land use and cover extent on birds between 2003-2012, accounting for imperfect detection probabilities using a Bayesian hierarchical, multi-species and multi-season occupancy model. We tested predictions that species diversity is positively related to habitat heterogeneity, which in intensified agroecosystems is thought to be mediated by food availability; thus the extent of land use and cover is predicted to affect foraging guilds differently. We also infer about ecosystem services provisioning and inform management recommendations for conservation of birds. Overall our results support the predictions. Although many species within each guild responded differently to land use and native forest cover, we identified generalities for most trophic guilds. For example, granivorous gleaners, ground insectivores and omnivores responded negatively to high proportions of soybean, while insectivore gleaners and aerial foragers seemed more tolerant. Habitat heterogeneity would likely benefit most species in an intensified agroecosystem, and can be achieved with a diversity of crops, pastures, and natural areas within the landscape. Although most studied species are insectivores, potentially beneficial for pest control, some guilds such as ground insectivores are poorly represented, suggesting that agricultural intensification reduces ecological functions, which may be recovered through management. Continuation of the bird monitoring program will allow

  14. Dual Ionic and Organic Nature of Ionic Liquids

    Science.gov (United States)

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquids—a molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs.

  15. Self-interaction error in DFT-based modelling of ionic liquids.

    Science.gov (United States)

    Lage-Estebanez, Isabel; Ruzanov, Anton; García de la Vega, José M; Fedorov, Maxim V; Ivaništšev, Vladislav B

    2016-01-21

    The modern computer simulations of potential green solvents of the future, involving the room temperature ionic liquids, heavily rely on density functional theory (DFT). In order to verify the appropriateness of the common DFT methods, we have investigated the effect of the self-interaction error (SIE) on the results of DFT calculations for 24 ionic pairs and 48 ionic associates. The magnitude of the SIE is up to 40 kJ mol(-1) depending on the anion choice. Most strongly the SIE influences the calculation results of ionic associates that contain halide anions. For these associates, the range-separated density functionals suppress the SIE; for other cases, the revPBE density functional with dispersion correction and triple-ζ Slater-type basis is suitable for computationally inexpensive and reasonably accurate DFT calculations. PMID:26690957

  16. Studies on the properties of ionic liquid BMIInCl4

    Institute of Scientific and Technical Information of China (English)

    Yang Jiazhen; Zhang Qingguo; Huang Ming; Xue Feng; Zang Shuliang

    2006-01-01

    An ionic liquid (IL) was prepared by directly mixing InCl3 and 1-methyl-3-butylimidazolium chloride(BMIC) with molar ratio 1:1 under dry argon atmosphere.The densities,and surface tension of pure IL were determined at temperature range of (278.15 to 343.15±0.1K).The properties for ionic liquid based on group Ⅲ were discussed using Glasser's theory.The standard entropy,the surface energy and the crystal energy of ionic liquid were calculated,respectively.The crystal energy of ionic liquid is much lower than ionic solid and this is the underlying reason for forming ionic liquid at room temperature.In addition,a new theoretical model of IL,that is interstice model,was applied to calculate the thermal expansion coefficient of BMIInCl4.The order of magnitude for the thermal expansion coefficient,a,calculated by the theoretical model is in good agreement with experimental value.The result shows that there is much reasonableness for the interstice model of ionic liquid.

  17. Development of a multi-species method by GC-coupling with inductively coupled plasma isotope dilution mass spectrometry for the simultaneous determination of alkylated lead, mercury and tin compounds

    OpenAIRE

    Poperechna, Nataliya

    2005-01-01

    An accurate and sensitive species-specific GC-ICP-IDMS (gas chromatography inductively coupled plasma isotope dilution mass spectrometry) method for the determination of trimethyllead and a multi-species-specific GC-ICP-IDMS method for the simultaneous determination of trimethyllead, methylmercury, and butyltins in biological and environmental samples were developed. They allow the determination of corresponding elemental species down to the low ng g-1 range. The developed synthesis scheme fo...

  18. Ionic conductivity in irradiated KCL

    International Nuclear Information System (INIS)

    The ionic conductivity of X and gamma irradiated KCL single crystals has been studied between room temperature and 600 degree centigree. the radiation induced damage resulting in a decrease of the conductivity heals by thermal annealing in two steps which are at about 350 and 550 degree centigree respectively. It has been found that the radiation induced colour centres are not involved in the observed decrease of the ionic conductivity. However. It has been observed that the effects of quenching and plastic deformation on the conductivity of the samples are very similar to the effect induced by irradiation. It is suggested that, samples radiation induced dislocation loops might cause the ionic conductivity decrease observed in irradiated samples. (Author)

  19. Ionic strength dependence of formation constants and complexation of glutamine with dioxovanadium(V)

    International Nuclear Information System (INIS)

    The dependence of L-glutamine protonation and its complexation with dioxovanadium(V) on ionic strength (I) is reported in sodium perchlorate solutions as a background salt. The measurements have been performed at 25 ±0.1 Deg C and various ionic strengths in the range 0.1 to 1.0 mol/l, using a combination of potentiometric and spectrophotometric techniques. The overall analysis of the present and the previous data dealing with the determination of stability constants at different ionic strengths allowed to obtain a general equation, by which a formation constant determined at a fixed ionic strength can be calculated, with a good approximation, at another ionic strength, if 0.1≤I≤1.0 mol/l

  20. Ionic conducting poly-benzimidazoles

    International Nuclear Information System (INIS)

    Over the last years, many research works have been focused on new clean energy systems. Hydrogen fuel cell seems to be the most promising one. However, the large scale development of this technology is still limited by some key elements. One of them is the polymer electrolyte membrane 'Nafion' currently used, for which the ratio performance/cost is too low. The investigations we carried out during this thesis work are related to a new class of ionic conducting polymer, the sulfonated poly-benzimidazoles (sPBI). Poly-benzimidazoles (PBI) are aromatic heterocyclic polymers well-known for their excellent thermal and chemical stability. Ionic conduction properties are obtained by having strong acid groups (sulfonic acid SO3H) on the macromolecular structure. For that purpose, we first synthesized sulfonated monomers. Their poly-condensation with an appropriate non-sulfonated co-monomer yields to sPBI with sulfonation range from 0 to 100 per cent. Three different sPBI structures were obtained, and verified by appropriate analytical techniques. We also showed that the protocol used for the synthesis resulted in high molecular weights polymers. We prepared ionic conducting membrane by casting sPBI solutions on glass plates. Their properties of stability, water swelling and ionic conductivity were investigated. Surprisingly, the behaviour of sPBI was quite different from the other sulfonated aromatic polymers with same amount of SO3H, their stability was much higher, but their water swelling and ionic conductivity were quite low. We attributed these differences to strong ionic interactions between the sulfonic acid groups and the basic benzimidazole groups of our polymers. However, we managed to solve this problem synthesizing very highly sulfonated PBI, obtaining membranes with a good balance between all the properties necessary. (author)

  1. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure

    Science.gov (United States)

    Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.; Ribeiro, Mauro C. C.; Giles, Carlos

    2016-06-01

    X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2]. The peak in the diffraction data characteristic of charge ordering in [N1444][NTf2] is shifted to longer distances in comparison to [N1114][NTf2], but the peak characteristic of short-range correlations is shifted in [N1444][NTf2] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N1114]+ and [N1444]+ proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N1444]+ as to [N1114]+ because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N1114]+ cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N1114][NTf2], whereas polar and non-polar structure factors are essentially the same in [N1444][NTf2]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids.

  2. Local fields in ionic crystals

    International Nuclear Information System (INIS)

    Local fields arising from the electronic distortion in perfect ionic crystals are described in terms of multipolar excitations. Field factors for the alkali halides and chalcogenide ions are found to differ significantly from the Lorentz value of 4π/3, the correction size following an exponential dependence on the difference in ionic radii. Local fields are only slightly modified by these corrections however, and together with the Clausius-Mossotti relation may be regarded as accurate to within 2% if the Lorentz value is adopted. (author)

  3. Ionic Capillary Evaporation in Weakly Charged Nanopores

    OpenAIRE

    Buyukdagli, Sahin; MANGHI, Manoel; Palmeri, John

    2010-01-01

    Using a variational field theory, we show that an electrolyte confined to a neutral cylindrical nanopore traversing a low dielectric membrane exhibits a first-order ionic liquid-vapor pseudo-phase-transition from an ionic-penetration "liquid" phase to an ionic-exclusion "vapor" phase, controlled by nanopore-modified ionic correlations and dielectric repulsion. For weakly charged nanopores, this pseudotransition survives and may shed light on the mechanism behind the rapid switching of nanopor...

  4. Gaseous Hydrocarbon Separations Using Functionalized Ionic Liquids

    OpenAIRE

    Moura Leila; Santini Catherine C.; Costa Gomes Margarida F.

    2016-01-01

    The functionalization of the side chains on the cation or the anion of an ionic liquid is a common approach to tailor its properties for different processes including the separation of gases. In this paper, we present the current state of the art concerning the usage of ionic liquids for hydrocarbon separations. We also show how the functionalization of ionic liquids or the appropriate anion/cation combinations can contribute to the increase of the performance of the ionic liquids for the sep...

  5. Evaporation from an ionic liquid emulsion.

    Science.gov (United States)

    Friberg, Stig E

    2007-03-15

    The conditions during evaporation in a liquid crystal-in-ionic liquid microemulsion (LC/microEm) were estimated using the phase diagram of the system. The equations for selected tie lines were established and the coordinates calculated for the sites, at which the evaporation lines crossed the tie lines. These values combined with the coordinates for the phases connecting the tie lines were used to calculate the amounts and the composition of the fractions of the two phases present in the emulsion during the evaporation. One of the emulsion phases was a lamellar liquid crystal and high energy emulsification would lead to the liquid crystal being disrupted to form vesicles. Such a system tenders a unique opportunity to study the interaction between vesicles and normal micelles, which gradually change to inverse micelles over bi-continuous structures. The amount of vesicles in the liquid phase versus the fraction liquid crystal was calculated for two extreme cases of vesicle core size and shell thickness. The limit of evaporation while retaining the vesicle structure was calculated for emulsions of different original compositions assuming the minimum continuous liquid phase to be 50% of the emulsion. PMID:17207810

  6. Application of Ionic Liquids in Hydrometallurgy

    OpenAIRE

    Jesik Park; Yeojin Jung; Priyandi Kusumah; Jinyoung Lee; Kyungjung Kwon; Churl Kyoung Lee

    2014-01-01

    Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing...

  7. Ionic-Liquid-Tethered Nanoparticles: Hybrid Electrolytes

    KAUST Repository

    Moganty, Surya S.

    2010-10-22

    A new class of solventless electrolytes was created by tethering ionic liquids to hard inorganic ZrO2 nanostructures (see picture; NIM=nanoscale ionic material). These hybrid fluids exhibit exceptional redox stability windows, excellent thermal stability, good lithium transference numbers, long-term interfacial stability in the presence of a lithium anode and, when doped with lithium salt, reasonable ionic conductivities.

  8. Lipid processing in ionic liquids

    DEFF Research Database (Denmark)

    Lue, Bena-Marie; Guo, Zheng; Xu, Xuebing

    2007-01-01

    Ionic liquids (ILs) have been touted as “green” alternatives to traditional molecular solvents and have many unique properties which make them extremely desirable substitutes. Among their most attractive properties are their lack of vapour pressure, broad liquid range, strong solvating power and...

  9. Helium solubility in imperfect ionic crystals

    International Nuclear Information System (INIS)

    In the context of the intended use of helium as a coolant in high temperature gas cooled reactors a study is undertaken into helium interaction with crystals at the stage preceding the process of helium clusters formation. Experimental and theoretical investigations of helium solubility in imperfect ionic crystals CaF2, SrF2, KBr are carried out along with the degassing kinetics in the temperature range of 500-1200 K. An analysis is made for possible mechanisms of the occurrence of observed oscillations in helium solubility at temperature variations. The solution heat for helium atoms in cation vacancies and the energy of impurity-vacancy cluster dissociation are calculated. The reason for a catastrophic increase of dissolved helium concentration with saturation pressure is discussed

  10. Simultaneous Design of Ionic Liquids and Azeotropic Separation for Systems Containing Water

    DEFF Research Database (Denmark)

    Roughton, Brock; Camarda, Kyle V.; Gani, Rafiqul

    fraction of water at the azeotrope is less than 30%. For promising ionic liquid candidates, the extractive distillation processes were designed using a reverse simulation approach and characterized in terms of the driving force (calculated from the predicted vapor-liquid equilibria) that corresponds to the...... optimal design of the separation process (in terms of number of stages, feed plate location, energy used, solvent loss, environmental impact, etc.). To ensure the feasibility of ionic liquids to be used as industrial entrainers, a correlation was also made relating molecular structure to thermal...... decomposition temperature. For any new synthesis-design problem involving aqueous azeotropes, all it now requires is to find the azeotropic composition of water and based on it, to identify an appropriate ionic liquid. Then the driving force is calculated for the azeotrope ionic liquid and based on it, the...

  11. Simulation of Ionic Aggregation and Ion Dynamics in Model Ionomers

    Science.gov (United States)

    Frischknecht, Amalie L.

    2012-02-01

    Ionomers, polymers containing a small fraction of covalently bound ionic groups, are of interest as possible electrolytes in batteries. A single-ion conducting polymer electrolyte would be safer and have higher efficiency than the currently-used liquid electrolytes. However, to date ionomeric materials do not have sufficiently high conductivities for practical application. This is most likely because the ions tend to form aggregates, leading to slow ion transport. A key question is therefore how molecular structure affects the ionic aggregation and ion dynamics. To probe these structure-property relationships, we have performed molecular simulations of a set of recently synthesized poly(ethylene-co-acrylic acid) copolymers and ionomers, with a focus on the morphology of the ionic aggregates. The ionomers have a precise, constant spacing of charged groups, making them ideal for direct comparisons with simulations. Ab initio calculations give insight into the expected coordination of cations with fragments of the ionomers. All-atom molecular dynamics (MD) simulations of the ionomer melt show aggregation of the ionic groups into extended string-like clusters. An extensive set of coarse-grained molecular dynamics simulations extend the results to longer times and larger length scales. The structure factors calculated from the MD simulations compare favorably with x-ray scattering data. Furthermore, the simulations give a detailed picture of the sizes, shapes, and composition of the ionic aggregates, and how they depend on polymer architecture. Implications for ion transport will be discussed. [Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Reconciling the ionic and covalent pictures in rare-earth nickelates

    OpenAIRE

    Varignon, Julien; Grisolia, Mathieu N.; Íñiguez, Jorge; Barthélémy, Agnès; Bibes, Manuel

    2016-01-01

    The properties of AMO3 perovskite oxides, where M is a 3d transition metal, depend strongly on the level of covalency between the metal d and oxygen p orbitals. With their complex spin orders and metal-insulator transition, rare-earth nickelates verge between dominantly ionic and covalent characters. Accordingly, the nature of their ground state is highly debated. Here, we reconcile the ionic and covalent visions of the insulating state of nickelates. Through first-principles calculations, we...

  13. Ionic flotation of strontium 89

    International Nuclear Information System (INIS)

    The experimental results on 89Sr ionic flotation out of sewage after deactivation using sodium dodecylbenzene sulfonate (DBSNa) as a foamer. Strontium was used in the form of SrCl2 at the 1.5-2.0 μCi/l isotopic concentration. It is established that the best condition of 89Sr flotation is the 2.0-2.5 pH range. During ionic flotation interaction of 89Sr microquantities with DBSNa has in the main an ion exchange character. The experimental data satisfactorily obey the equation being a consequence of the law of mass action. The process kinetics can be described by the equation of the first-order reaction

  14. Ionic liquids for enzymatic sensing

    OpenAIRE

    Fraser, Kevin J.

    2012-01-01

    Point-of-care (POC) glucose biosensors play an important role in the management of blood sugar levels in patients with diabetes. One of the most commonly used enzymes in glucose biosensors is Glucose Oxidase (GOx). It is a biorecognition enzyme, which recognises the glucose molecule and acts as a catalyst to produce gluconic acid and hydrogen peroxide in the presence of glucose and oxygen. Ionic liquids (ILs) have evolved as a new type of solvent for biocatalysis, mainly due to their uniq...

  15. Ionic Liquids to Replace Hydrazine

    Science.gov (United States)

    Koelfgen, Syri; Sims, Joe; Forton, Melissa; Allan, Barry; Rogers, Robin; Shamshina, Julia

    2011-01-01

    A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

  16. Separation of thiophene from heptane with ionic liquids

    International Nuclear Information System (INIS)

    Highlights: ► The ternary (liquid + liquid) equilibria in 1-butyl-1-methylpyrrolidinium-based ILs was measured. ► High selectivity and distribution ratio for the extraction of thiophene was found. ► [BMPYR][TCM] was proposed as entrainer for the separation process. ► Extraction of sulphur-compounds from alkanes was proposed. -- Abstract: Ionic liquids (ILs) are well known novel green solvents, which can be used for removing sulfur compounds from gasoline and diesel oils. Ternary (liquid + liquid) equilibrium data are presented for mixtures of {ionic liquid (1) + thiophene (2) + heptane (3)} at T = 298.15 K and ambient pressure to analyze the performance of the ionic liquid (IL) in the extraction of thiophene from the alkanes. Three pyrrolidinium-based ionic liquids have been studied: 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, ([BMPYR][FAP]), 1-butyl-1-methylpyrrolidinium tetracyanoborate, [BMPYR][TCB] and 1-butyl-1-methylpyrrolidinium tricyanomethanide, [BMPYR][TCM]. The results are discussed in terms of the selectivity and distribution ratio of separation of related systems. The immiscibility in the binary liquid systems of (thiophene + heptane) with all used ILs was observed. The [TCM]− anion in comparison with [TCB]− and [FAP]− anions shows much higher selectivity and slightly lower distribution ratio for extraction of thiophene. The non-random two liquid NRTL model was used successfully to correlate the experimental tie-lines and to calculate the phase composition error in mole fraction in the ternary systems. The average root mean square deviation (RMSD) of the phase composition was 0.047. The densities of [BMPYR][TCM] in temperature range from (298.15 to 348.15) K were measured. The data presented here show that the [BMPYR][TCM] ionic liquid can be used as an alternative solvent for the separation of thiophene from the hydrocarbon stream using solvent liquid–liquid extraction at ambient conditions

  17. Densities and refractive indices of imidazolium- and phosphonium-based ionic liquids: Effect of temperature, alkyl chain length, and anion

    Energy Technology Data Exchange (ETDEWEB)

    Tariq, M.; Forte, P.A.S. [Instituto de Tecnologia Quimica e Biologica, UNL, Av. Republica, Apt. 127, 2780-901 Oeiras (Portugal); Gomes, M.F. Costa [Laboratoire de Thermodynamique et Interactions Moleculaires, Universite Blaise Pascal, Clermont-Ferrand/C.N.R.S., 24 Avenue des Landais, 63177 Aubiere (France); Lopes, J.N. Canongia [Instituto de Tecnologia Quimica e Biologica, UNL, Av. Republica, Apt. 127, 2780-901 Oeiras (Portugal); Centro de Quimica Estrutural, Instituto Superior Tecnico. Av. Rovisco Pais, 1049-001 Lisboa (Portugal)], E-mail: jnlopes@ist.utl.pt; Rebelo, L.P.N. [Instituto de Tecnologia Quimica e Biologica, UNL, Av. Republica, Apt. 127, 2780-901 Oeiras (Portugal)], E-mail: luis.rebelo@itqb.unl.pt

    2009-06-15

    A systematic study of densities and refractive indices of 17 room temperature ionic liquids is presented at four different temperatures ranging from 293 K to 333 K. The ionic liquids are grouped into four families: 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [C{sub n}mim][Ntf{sub 2}], ionic liquids (with n = 2, 4, 6, 8, 10, 12, and 14); 1-alkyl-3-methylimidazolium hexafluorophosphate, [C{sub n}mim][PF{sub 6}], ionic liquids (with n = 4, 6, 8); ionic liquids based on the trihexyl(tetradecyl)phosphonium cation, [P{sub 66614}], combined with the anions bis(trifluoromethylsulfonyl)amide, [Ntf{sub 2}], acetate, [OAc], and triflate, [OTf]; and [C{sub 4}mim]-based ionic liquids combined with the anions [OAc], [OTf], methylsulfate [MeSO{sub 4}], and tetrafluoroborate [BF{sub 4}]. The data obtained were analysed to determine the effect of (i) temperature, (ii) the alkyl chain length of the 1-alkyl-3-methylimidazolium cation, and (iii) the nature of the anion. Different empirical models for the calculation of the densities of the ionic liquids were tested. Molar refractions were also calculated from the volumetric and refractive index data and the values were discussed with the aim of checking their utility in obtaining insights on the intermolecular forces and behaviour in solution of the different ionic liquids.

  18. Flow equations for the ionic Hubbard model

    Science.gov (United States)

    Hafez, Mohsen; Jafari, S. A.; Abolhassani, M. R.

    2009-12-01

    Taking the site-diagonal terms of the ionic Hubbard model (IHM) in one and two spatial dimensions, as H, we employ Continuous Unitary Transformations (CUT) to obtain a “classical” effective Hamiltonian in which hopping term has been renormalized to zero. For this Hamiltonian spin gap and charge gap are calculated at half-filling and subject to periodic boundary conditions. Our calculations indicate two transition points. In fixed Δ, as U increases from zero, there is a region in which both spin gap and charge gap are positive and identical; characteristic of band insulators. Upon further increasing U, first transition occurs at U=Uc_1, where spin and charge gaps both vanish and remain zero up to U=Uc_2. A gap-less state in charge and spin sectors characterizes a metal. For U>Uc_2 spin gap remains zero and charge gap becomes positive. This third region corresponds to a Mott insulator in which charge excitations are gaped, while spin excitations remain gap-less.

  19. Ionic parachor and its application to pyridinium-based ionic liquids of {[Cnpy][DCA] (n = 2, 3, 4, 5, 6)}

    International Nuclear Information System (INIS)

    Highlights: • Three novel ILs [Cnpy][DCA] (n = 3, 5, 6) were synthesized successfully. • The parachors of pyridinium cations, [Cnpy]+ (n = 2, 3, 4, 5, 6), were obtained. • P(Est), γ(Pred), nD(Pred) correlate quite well with P(Exp), γ(Exp), nD(Exp). • If the structure of cation or anion is the same, P+ or P− is approximately equal. - Abstract: Three novel dicyanamide ionic liquids (ILs) [Cnpy][DCA] (n = 3, 5, 6) and two [Cnpy][DCA] (n = 2, 4) (N-alkyl-pyridinium dicyanamide) were prepared and characterized by 1H NMR spectroscopy, 13C NMR spectroscopy, differential scanning calorimetry (DSC), High Performance Liquid Chromatography (HPLC) and FT-IR spectroscopy. The density, surface tension and refractive index were determined by the standard addition method (SAM) at T = 298.15 K. The experiment values of parachor for [Cnpy][DCA] (n = 2, 3, 4, 5, 6) were calculated and the ionic parachor of anion, [DCA]− as a reference ion was obtained in terms of the extrathermodynamic assumption, and then the ionic parachor, P+, of all corresponding pyridinium cations, [Cnpy]+, were obtained. Using the values of P+ of [Cnpy]+ and [Cnmim]+ in our previous papers, the values of ionic parachor for 10 kinds of anions were obtained. By using the ionic parachor, the values of parachor for 47 ionic liquids were obtained, which are more closed to their experiment values than the values of parachor obtained by Rowley et al. The values of surface tension for 52 ionic liquids and the values of refractive index for 22 ionic liquids were predicted using the estimated values of parachor with their experimental expanded uncertainty at 0.95 confidence level of ±0.3 mJ · m−2 and ±0.0003, respectively

  20. Solubility of xylitol and sorbitol in ionic liquids – Experimental data and modeling

    International Nuclear Information System (INIS)

    Highlights: ► Measurements of density of three pure ionic liquids. ► Empirical correlation of density data. ► Solubility measurement for two alditols in three ionic liquids. ► Correlation of the solubility data using local composition models. ► Calculation of the apparent thermodynamic functions of dissolution. - Abstract: Solubility of biomass-derived compounds in ionic liquids is an important parameter for the design of future processes incorporating ionic liquids as solvents for biorefining. Sugar alcohols such as sorbitol and xylitol are carbohydrate derivatives which have been identified as building blocks for biorefining. Therefore, in this work the solubility of these two sugar alcohols was measured experimentally within the temperature range of 288 K to 433 K, in three ionic liquids: [emim][EtSO4], Aliquat®336 (N-Methyl-N,N-dioctyloctan-1-ammonium chloride), and Aliquat®[NO3] (N-Methyl-N,N-dioctyloctan-1-ammonium nitrate). In addition, the densities of the ionic liquids were also measured and correlated. Local composition models such as NRTL, e-NRTL, and UNIQUAC were successfully applied to represent the experimental solubility data. The thermodynamic functions of dissolution were also calculated from the experimental data.

  1. Atomistic insight into orthoborate-based ionic liquids: force field development and evaluation.

    Science.gov (United States)

    Wang, Yong-Lei; Shah, Faiz Ullah; Glavatskih, Sergei; Antzutkin, Oleg N; Laaksonen, Aatto

    2014-07-24

    We have developed an all-atomistic force field for a new class of halogen-free chelated orthoborate-phosphonium ionic liquids. The force field is based on an AMBER framework with determination of force field parameters for phosphorus and boron atoms, as well as refinement of several available parameters. The bond and angle force constants were adjusted to fit vibration frequency data derived from both experimental measurements and ab initio calculations. The force field parameters for several dihedral angles were obtained by fitting torsion energy profiles deduced from ab initio calculations. To validate the proposed force field parameters, atomistic simulations were performed for 12 ionic liquids consisting of tetraalkylphosphonium cations and chelated orthoborate anions. The predicted densities for neat ionic liquids and the [P6,6,6,14][BOB] sample, with a water content of approximately 2.3-2.5 wt %, are in excellent agreement with available experimental data. The potential energy components of 12 ionic liquids were discussed in detail. The radial distribution functions and spatial distribution functions were analyzed and visualized to probe the microscopic ionic structures of these ionic liquids. There are mainly four high-probability regions of chelated orthoborate anions distributed around tetraalkylphosphonium cations in the first solvation shell, and such probability distribution functions are strongly influenced by the size of anions. PMID:25020237

  2. Ionic Liquids: Green Solvents for Chemical Processing

    OpenAIRE

    Antonia Pérez de los Ríos; Angel Irabien; Frank Hollmann; Francisco José Hernández Fernández

    2013-01-01

    Ionic liquids are organic salts, usually consisting of an organic cation and a polyatomic inorganic anion, which are liquid under 100∘ C. The most relevant properties of ionic liquids are their almost negligible vapour pressure. Furthermore, their physical and chemical properties can be fine-tuned by the adequate selection of the cation and anion constituents. Ionic liquids have been recognized as environmental benign alternative to volatile organic solvents. Applicati...

  3. Photochemical Schiemann Reaction in Ionic Liquids

    OpenAIRE

    Heredia-Moya, Jorge; Kirk, Kenneth L.

    2007-01-01

    Photochemical Schiemann reactions of imidazole derivatives 1 and 4 were carried out in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid [bmim][BF4] as solvent. The effects of temperature, co-solvent and wavelength on the rate of the reaction and product yield were examined. The use of ionic liquid increases the yield of the photochemical fluorodediazoniation reaction of 2 at 0°C. Careful temperature control is necessary to minimize the photodecomposition of the ionic liquid in order...

  4. Rearrangement reactions in ionic liquid media

    OpenAIRE

    Sarmīte Katkeviča

    2009-01-01

    ABSTRACT Ph.D. theses „Rearrangement reactions in ionic liquid media” are devoted to the subject that has gained great actuality and large popularity today - ionic liquids. The research about three different by reaction mechanisms organic transformations – Fries, Beckmann and Claisen rearrangement reactions in ionic liquid media is discussed in the thesis. The novelty of the research is connected with the replacement of organic solvents with environmentally friendly material...

  5. Quantized Friction across Ionic Liquid Thin Films

    OpenAIRE

    Smith, Alexander M.; Lovelock, Kevin R. J.; Gosvami, Nitya Nand; Welton, Tom; Perkin, Susan

    2013-01-01

    Ionic liquids, salts in the liquid state under ambient conditions, are of great interest as precision lubricants. Ionic liquids form layered structures at surfaces, yet it is not clear how this nano-structure relates to their lubrication properties. We measured the friction force between atomically smooth solid surfaces across ionic liquid films of controlled thickness in terms of the number of ion layers. Multiple friction-load regimes emerge, each corresponding to a different number of ion ...

  6. CO2 Solubilities in Amide-based Brφnsted Acidic Ionic Liquids

    International Nuclear Information System (INIS)

    A distinguished class of hydrophobic ionic liquids bearing a Brφnsted acidic character derived from amide-like compounds were prepared by a neutralization reaction of N,N-diethylformamide, N,N-dibutylformamide, 1-formylpiperidine, and ε-caprolactam with trifluoroacetic acid and physical absorptions of CO2 in these ionic liquids were demonstrated and evaluated. CO2 solubilities in these ionic liquids were influenced by the molecular structure of the cation and were apparently increased with the molar volume. Comparison based on a volume unit reveals that CO2 solubilities in these liquids are relatively higher than those in imidazolium-based ionic liquids. Henry's coefficients calculated from low-pressure solubility tests at 313 to 333 K were used to derive the thermodynamics quantities. Enthalpy and entropy of solvation may share equal contributions in solubility

  7. Thermodynamic studies on protonation constant of adenosine and guanosine at different temperatures and ionic strengths

    International Nuclear Information System (INIS)

    Highlights: • Protonation constants of adenosine and guanosine were determined. • The dependence of temperature and ionic strength were characterized. • Potentiometric and spectrophotometric methods were used. - Abstract: Stepwise protonation constants of two purine nucleosides (adenosine and guanosine) were determined at different temperatures (293.15 to 308.15) and various ionic strengths (0.101 to 3.503 mol · kg−1 NaClO4) using a combination of potentiometric and spectrophotometric method. The thermodynamic parameters (i.e. enthalpy change, ΔH, and entropy change, ΔS) of the protonations were calculated at different temperatures using van’t Hoff and virial equations. The dependence of the protonation constant on ionic strength is modeled by a Debye–Hückel type equation and discussed. Finally, the protonation constants of the nucleosides and the enthalpy change of protonations were determined at zero ionic strength

  8. Local character of magnetic coupling in ionic solids

    Science.gov (United States)

    Moreira, Ibério De P. R.; Illas, Francesc; Calzado, Carmen J.; Sanz, Javier F.; Malrieu, Jean-Paul; Ben Amor, Nadia; Maynau, Daniel

    1999-03-01

    Magnetic interactions in ionic solids are studied using parameter-free methods designed to provide accurate energy differences associated with quantum states defining the Heisenberg constant J. For a series of ionic solids including KNiF3, K2NiF4, KCuF3, K2CuF4, and high- Tc parent compound La2CuO4, the J experimental value is quantitatively reproduced. This result has fundamental implications because J values have been calculated from a finite cluster model whereas experiments refer to infinite solids. The present study permits us to firmly establish that in these wide-gap insulators, J is determined from strongly local electronic interactions involving two magnetic centers only thus providing an ab initio support to commonly used model Hamiltonians.

  9. Synthesis and Characterization of Tetramethylethylenediamine-Based Hypergolic Ionic Liquids

    Science.gov (United States)

    Fei, Teng; Cai, Huiwu; Zhang, Yanqiang; Liu, Long; Zhang, Suojiang

    2016-04-01

    Four energetic salts (including two ionic liquids) based on 2-(dimethylamino)-N,N,N-trimethylethanaminium and N,N‧-dialkyl-N,N,N‧,N‧-tetramethylethane-1,2-diaminium was prepared and characterized by 1H- and 13C-NMR, infrared and Raman spectroscopies, and elemental analysis. Their physicochemical properties such as melting and decomposition temperatures, density, viscosity, heat of formation, detonation performance, and specific impulse were measured or calculated. With thermal stability up to 200°C, the resulting ionic liquids show densities from 1.02 to 1.19 g cm-3 and heats of formation from 85.1 to 154.4 kJ mol-1. Moreover, 2-(dimethylamino)-N,N,N-trimethylethanaminium dicyanamide is hypergolic with the oxidizer (100% HNO3) and exhibits potential as a green fuel for bipropellants.

  10. Electrodeposition of magnesium film from BMIMBF4 ionic liquid

    International Nuclear Information System (INIS)

    In this paper, we reported for the first time magnesium electrodeposition and dissolution processes in the ionic liquid of BMIMBF4 with 1 M Mg(CF3SO3)2 at room temperature. Our study found that complete electrochemical reoxidation of the electrodeposited magnesium film was feasible only on Ag substrate, comparing with the Pt, Ni, and stainless-steel. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) results showed that magnesium was found in the deposited film and the deposits were dense. The electrodeposition of magnesium on Ag substrate in the ionic liquid was considered to be a reversible process by cyclic voltammetry. Plots of peak current versus the square root of the scan rate were found to be linear, which indicates that the mass-transport process of electroactive species was mainly diffusion controlled. The diffusion coefficient D values of electroactive species were calculated from cyclic voltammetry and chronoamperometry, respectively

  11. Sequencing proteins with transverse ionic transport in nanochannels

    CERN Document Server

    Boynton, P

    2015-01-01

    {\\it De novo} protein sequencing is essential for understanding cellular processes that govern the function of living organisms and all post-translational events and other sequence modifications that occur after a protein has been constructed from its corresponding DNA code. By obtaining the order of the amino acids that composes a given protein one can then determine both its secondary and tertiary structures through structure prediction, which is used to create models for protein aggregation diseases such as Alzheimer's Disease. Mass spectrometry is the current technique of choice for {\\it de novo} sequencing. However, because some amino acids have the same mass the sequence cannot be completely determined in many cases. Here, we propose a new technique for {\\it de novo} protein sequencing that involves translocating a polypeptide through a synthetic nanochannel and measuring the ionic current of each amino acid through an intersecting {\\it perpendicular} nanochannel. To calculate the transverse ionic curre...

  12. Improved Ionic Liquids as Space Lubricants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Ionic liquids are candidate lubricant materials. However for application in low temperature space mechanisms their lubrication performance needs to be enhanced. UES...

  13. Membrane separation of ionic liquid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Daniel; Feiring, Andrew Edward; Majumdar, Sudipto; Nemser, Stuart

    2015-09-01

    A membrane separation process using a highly fluorinated polymer membrane that selectively permeates water of an aqueous ionic liquid solution to provide dry ionic liquid. Preferably the polymer is a polymer that includes polymerized perfluoro-2,2-dimethyl-1,3-dioxole (PDD). The process is also capable of removing small molecular compounds such as organic solvents that can be present in the solution. This membrane separation process is suitable for drying the aqueous ionic liquid byproduct from precipitating solutions of biomass dissolved in ionic liquid, and is thus instrumental to providing usable lignocellulosic products for energy consumption and other industrial uses in an environmentally benign manner.

  14. Supported Ionic Liquid Phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco;

    2006-01-01

    Applications of ionic liquids to replace conventional solvents in homogeneous transition-metal catalysis have increased significantly during the last decade. Biphasic ionic liquid/organic liquid systems offer advantages with regard to product separation, catalyst stability, and recycling but...... utilise in the case of fast chemical reactions only a small amount of expensive ionic liquid and catalyst. The novel Supported Ionic Liquid Phase (SILP) catalysis concept overcomes these drawbacks and allows the use of fixed-bed reactors for continuous reactions. In this Microreview the SILP catalysis...

  15. Ionic self-assembly affords mesoporous ionic networks by crosslinking linear polyviologens with polyoxometalate clusters.

    Science.gov (United States)

    Chen, Guojian; Hou, Wei; Li, Jing; Wang, Xiaochen; Zhou, Yu; Wang, Jun

    2016-03-21

    Ionic-bonded mesoporous ionic networks were prepared by the ionic self-assembly of polyoxometalate (POM) clusters with linear cationic polyviologens in water. The POM-enriched PMIN-2(V) possesses a high surface area up to 120 m(2) g(-1), exhibiting superior non-noble metal heterogeneous catalytic performance in the ambient aerobic selective oxidation of 5-hydroxymethylfurfural. PMID:26898883

  16. Ionic liquid tunes microemulsion curvature.

    Science.gov (United States)

    Liu, Liping; Bauduin, Pierre; Zemb, Thomas; Eastoe, Julian; Hao, Jingcheng

    2009-02-17

    Middle-phase microemulsions formed from cationic dioctadecyldimethylammonium chloride (DODMAC), anionic sodium dodecylsulfate (SDS), n-butanol, and n-heptane were studied. An ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), was employed as the electrolyte in the aqueous media instead of inorganic salts usually used in microemulsion formulation. Studies have been carried out as a function of the concentrations of [bmim][BF4], n-butanol, total surfactant (cDODMAC+SDS), and temperature on the phase behavior and the ultralow interfacial tensions in which the anionic component is present in excess in the catanionic film. Ultralow interfacial tension measurements confirmed the formation of middle-phase microemulsions and the necessary conditions for stabilizing middle-phase microemulsions. Electrical conductivity, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) experiments were also performed, indicating that the typical heptane domain size has an average radius of 360 A and the ionic liquid induces softening of the charged catanionic film. Most interestingly, the IL concentration (cIL) is shown to act as an effective interfacial curvature-control parameter, representing a new approach to tuning the formulation of microemulsions and emulsions. The results expand the potential uses of ILs but also point to the design of new ILs that may achieve superefficient control over interfacial and self-assembly systems. PMID:19161325

  17. Aqueous solutions of ionic liquids: microscopic assembly

    NARCIS (Netherlands)

    J.M. Vicent-Luna; D. Dubbeldam; P. Gómez-Álvarez; S. Calero

    2016-01-01

    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactio

  18. Ionic liquid-in-oil microemulsions.

    Science.gov (United States)

    Eastoe, Julian; Gold, Sarah; Rogers, Sarah E; Paul, Alison; Welton, Tom; Heenan, Richard K; Grillo, Isabelle

    2005-05-25

    Phase stability and small-angle neutron scattering (SANS) data show that surfactant-stabilized nanodomains of a typical ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4]) may be dispersed by the nonionic surfactant Triton-X100 in cyclohexane. Analyses of these SANS data are consistent with the formation of ionic liquid-in-oil microemulsion droplets. PMID:15898765

  19. Improved ionic model of liquid uranium dioxide

    NARCIS (Netherlands)

    Gryaznov, [No Value; Iosilevski, [No Value; Yakub, E; Fortov, [No Value; Hyland, GJ; Ronchi, C

    2000-01-01

    The paper presents a model for liquid uranium dioxide, obtained by improving a simplified ionic model, previously adopted to describe the equation of state of this substance [1]. A "chemical picture" is used for liquid UO2 of stoichiometric and non-stoichiometric composition. Several ionic species a

  20. Engineered microorganisms having resistance to ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Ruegg, Thomas Lawrence; Thelen, Michael P.

    2016-03-22

    The present invention provides for a method of genetically modifying microorganisms to enhance resistance to ionic liquids, host cells genetically modified in accordance with the methods, and methods of using the host cells in a reaction comprising biomass that has been pretreated with ionic liquids.

  1. Gaseous Hydrocarbon Separations Using Functionalized Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Moura Leila

    2016-03-01

    Full Text Available The functionalization of the side chains on the cation or the anion of an ionic liquid is a common approach to tailor its properties for different processes including the separation of gases. In this paper, we present the current state of the art concerning the usage of ionic liquids for hydrocarbon separations. We also show how the functionalization of ionic liquids or the appropriate anion/cation combinations can contribute to the increase of the performance of the ionic liquids for the separation of gaseous hydrocarbons – either by improving the capacity of the ionic liquid to absorb a given gas or by increasing the selectivity towards a particular hydrocarbon. Original results concerning the usage of olefin-complexing metal salts of lithium (I, nickel (II and copper (II dissolved in ionic liquids for selectively absorbing light olefins are presented. It is observed that the absorption capacity of an imidazolium-based ionic liquid is doubled by the addition of a copper (II salt. This result is compared with the effect of the functionalization of the ionic liquid and the advantages and difficulties of the two approaches are analyzed.

  2. Ionic liquid incorporating thiosalicylate for metal removal

    Science.gov (United States)

    Wilfred, Cecilia Devi; Mustafa, Fadwa Babiker; Romeli, Fatimah Julia

    2012-09-01

    Ionic liquids are a class of organic molten salts "designer solvents" that are composed totally of anions (inorganic and organic polyatomic) and organic cations. The replacement of volatile organic solvents from a separation process is of utmost importance since the use of a large excess of these solvents is hazardous and creates ecological problem. The new method for metal ion extraction is by using task-specific ionic liquids such as ionic liquids which incorporate thiosalicylate functionality. This paper looks at producing a new cluster of ionic liquids which incorporates thiosalicylate with pyridinium cation. Its thermophysical properties such as density and viscosity in single and binary mixtures are studied. The ionic liquids' capability in metal removal processes is evaluated.

  3. Application of Ionic Liquids in Hydrometallurgy

    Directory of Open Access Journals (Sweden)

    Jesik Park

    2014-08-01

    Full Text Available Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry.

  4. Enhanced ionic diffusion in ionomer-filled nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Allahyarov, Elshad, E-mail: elshad.allakhyarov@case.edu [Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf (Germany); Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202 (United States); Theoretical Department, Joint Institute for High Temperatures, Russian Academy of Sciences (IVTAN), 13/19 Izhorskaya Street, Moscow 125412 (Russian Federation); International Research Centre, Baku State University, Baku (Azerbaijan); Taylor, Philip L. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079 (United States); Löwen, Hartmut [Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf (Germany)

    2015-12-28

    Coarse-grained simulations in the united-atom-model approximation are used to investigate confinement-induced morphological changes in Nafion-like ionomers. The system we study models a cylindrical pore in a hydrophobic matrix of supporting material with pore diameters that vary from 0.7 to 3.96 nm. Simulation results indicate a strong dependence of the equilibrium ionomer structures both on the pore diameter and on the sulfonate concentration in the pore. In the case of larger pores, the ionic clustering has the shape of a branched wire-like network oriented parallel to the pore axis. In the case of narrow pores, the ionic clusters occupy the pore center and exhibit strong density modulations both along the pore axis and across the pore diameter. The calculated diffusion coefficients for the ions indicate a sharp increase within the narrow pores. This finding is explained by ballistic-type ionic motion at shorter times and by the collective motion of ions in hydrophilic clusters. The influence of the hydrophobic walls on the distribution of ions and solvent molecules is discussed.

  5. A structural investigation of ionic liquid mixtures.

    Science.gov (United States)

    Matthews, Richard P; Villar-Garcia, Ignacio J; Weber, Cameron C; Griffith, Jeraime; Cameron, Fiona; Hallett, Jason P; Hunt, Patricia A; Welton, Tom

    2016-03-16

    The structures of mixtures of ionic liquids (ILs) featuring a common 1-butyl-3-methylimidazolium ([C4C1im](+)) cation but different anions have been investigated both experimentally and computationally. (1)H and (13)C NMR of the ILs and their mixtures has been performed both on the undiluted liquids and those diluted by CD2Cl2. These experiments have been complemented by quantum chemical density functional theory calculations and molecular dynamics simulations. These techniques have identified the formation of preferential interactions between H(2) of the imidazolium cation and the most strongly hydrogen bond (H-bond) accepting anion. In addition, a preference for the more weakly H-bond accepting anion to interact above the imidazolium ring through anion-π(+) interactions has been identified. The modelling of these data has identified that the magnitude of these preferences are small, of the order of only a few kJ mol(-1), for all IL mixtures. No clustering of the anions around a specific cation could be observed, indicating that these interactions arise from the reorientation of the cation within a randomly assigned network of anions. π(+)-π(+) stacking of the imidazolium cations was also studied and found to be promoted by ILs with a strong H-bond accepting anion. Stacking interactions are easily disrupted by the introduction of small proportions (accounting for why most IL mixtures exhibit ideal, or nearly ideal, behaviour. PMID:26947103

  6. Interaction of a Long Alkyl Chain Protic Ionic Liquid and Water

    CERN Document Server

    Bodo, Enrico; Capitani, Francesco; Gontrani, Lorenzo; Leonelli, Francesca; Postorino, Paolo

    2014-01-01

    A combined experimental/theoretical approach has been used to investigate the role of water in modifying the microscopic interactions characterizing the optical response of butyl-ammonium nitrate (BAN) water solutions. Raman spectra, dominated by the signal from the protic ionic liquid, were collected as a function of the water content, and the corresponding spatial organization of the ionic couples, as well as their local arrangement with water molecules, was studied exploiting classical molecular dynamics calculations. High quality spectroscopic data, combined with a careful analysis, revealed that water affects the vibrational spectrum BAN in solution: as the water concentration is increased, peaks assigned to stretching modes show a frequency hardening together with a shape narrowing, whereas the opposite behavior is observed for peaks assigned to bending modes. Calculation results clearly show a nanometric spatial organization of the ionic couples that is not destroyed on increasing the water content at ...

  7. Ternary (liquid + liquid) equilibria of {trifluorotris(perfluoroethyl)phosphate based ionic liquids + thiophene + heptane}: Part 2

    International Nuclear Information System (INIS)

    Highlights: • Ternary (liquid + liquid) equilibria for 3 ionic liquid + thiophene + heptane systems. • The influence of ionic liquid structure on phase diagrams is discussed. • Influence of IL structure on S and β for heptane/thiophene separation is discussed. - Abstract: Ternary (liquid + liquid) equilibria for 3 systems containing ionic liquids {(1-ethyl-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate, 1-(2-hydroxyethyl)-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate, ethyl-dimethyl-(2-methoxyethyl)ammonium trifluorotris(perfluoroethyl)phosphate) + thiophene + heptane} have been determined at T = 298.15 K. The selectivity and solute distribution ratio were calculated for investigated systems and compared with literature values obtained for other systems containing ionic liquids with [FAP]− anions and [emim]+ cations. In each system, high solubility of thiophene and low solubility of heptane in the ionic liquid are observed. The experimental results have been correlated using NRTL model. The influence of the structure of ionic liquid on phase equilibria, selectivity and solute distribution ratio is discussed

  8. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    International Nuclear Information System (INIS)

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed

  9. Understanding the impact of the central atom on the ionic liquid behavior: phosphonium vs ammonium cations.

    Science.gov (United States)

    Carvalho, Pedro J; Ventura, Sónia P M; Batista, Marta L S; Schröder, Bernd; Gonçalves, Fernando; Esperança, José; Mutelet, Fabrice; Coutinho, João A P

    2014-02-14

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed. PMID:24527930

  10. Structure of cyano-anion ionic liquids: X-ray scattering and simulations

    Science.gov (United States)

    Dhungana, Kamal B.; Faria, Luiz F. O.; Wu, Boning; Liang, Min; Ribeiro, Mauro C. C.; Margulis, Claudio J.; Castner, Edward W.

    2016-07-01

    Ionic liquids with cyano anions have long been used because of their unique combination of low-melting temperatures, reduced viscosities, and increased conductivities. Recently we have shown that cyano anions in ionic liquids are particularly interesting for their potential use as electron donors to excited state photo-acceptors [B. Wu et al., J. Phys. Chem. B 119, 14790-14799 (2015)]. Here we report on bulk structural and quantum mechanical results for a series of ionic liquids based on the 1-ethyl-3-methylimidazolium cation, paired with the following five cyano anions: SeCN-, SCN-, N(CN) 2 -, C(CN) 3 -, and B(CN) 4 -. By combining molecular dynamics simulations, high-energy X-ray scattering measurements, and periodic boundary condition DFT calculations, we are able to obtain a comprehensive description of the liquid landscape as well as the nature of the HOMO-LUMO states for these ionic liquids in the condensed phase. Features in the structure functions for these ionic liquids are somewhat different than the commonly observed adjacency, charge-charge, and polarity peaks, especially for the bulkiest B(CN) 4 - anion. While the other four cyano-anion ionic liquids present an anionic HOMO, the one for Im2,1 +/B(CN) 4 - is cationic.

  11. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Pedro J.; Ventura, Sónia P. M.; Batista, Marta L. S.; Schröder, Bernd; Coutinho, João A. P., E-mail: jcoutinho@ua.pt [CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Gonçalves, Fernando [Departamento de Biologia e CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, 3810-193 Aveiro (Portugal); Esperança, José [Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-901 Oeiras (Portugal); Mutelet, Fabrice [Laboratoire Réactions et Génie des Procédés, CNRS (UPR3349), Nancy-Université, 1 rue Grandville, BP 20451 54001 Nancy (France)

    2014-02-14

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.

  12. Infrared spectroscopy of ionic clusters

    International Nuclear Information System (INIS)

    This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm-1 region. The species studied include: the hydrated hydronium ions, H3O+ (H2O)3-10, ammoniated ammonium ions, NH4+(NH3)1-10 and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH4+(NH3)n(H2O)m (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs

  13. Infrared spectroscopy of ionic clusters

    Energy Technology Data Exchange (ETDEWEB)

    Price, J.M. (California Univ., Berkeley, CA (USA). Dept. of Chemistry Lawrence Berkeley Lab., CA (USA))

    1990-11-01

    This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm{sup {minus}1} region. The species studied include: the hydrated hydronium ions, H{sub 3}O{sup +} (H{sub 2}O){sub 3 {minus}10}, ammoniated ammonium ions, NH{sub 4}{sup +}(NH{sub 3}){sub 1 {minus}10} and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH{sub 4}{sup +}(NH{sub 3}){sub n}(H{sub 2}O){sub m} (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs.

  14. Catalysis in Molten Ionic Media

    DEFF Research Database (Denmark)

    Boghosian, Soghomon; Fehrmann, Rasmus

    2013-01-01

    identified easily. It has been shown that the melt consists of vanadium oxosulfato complexes in the oxidation states III-V in an alkali pyrosulfate solvent. However, many basic data for alkali pyrosulfates and oxosulfato vanadates have turned out to be either nonexisting or unreliable. As a result, the...... of vanadium compounds, of which the majority are identified as catalyst deactivation products; and (v) studies of molecular structure and catalytic activity. Finally, the reaction mechanism is highlighted, which represents the state of the art of that catalytic process by 2013. © 2013 Elsevier Inc......This chapter deals with catalysis in molten salts and ionic liquids, which are introduced and reviewed briefly, while an in-depth review of the oxidation catalyst used for the manufacturing of sulfuric acid and cleaning of flue gas from electrical power plants is the main topic of the chapter. The...

  15. Actinide chemistry in ionic liquids.

    Science.gov (United States)

    Takao, Koichiro; Bell, Thomas James; Ikeda, Yasuhisa

    2013-04-01

    This Forum Article provides an overview of the reported studies on the actinide chemistry in ionic liquids (ILs) with a particular focus on several fundamental chemical aspects: (i) complex formation, (ii) electrochemistry, and (iii) extraction behavior. The majority of investigations have been dedicated to uranium, especially for the 6+ oxidation state (UO2(2+)), because the chemistry of uranium in ordinary solvents has been well investigated and uranium is the most abundant element in the actual nuclear fuel cycles. Other actinides such as thorium, neptunium, plutonium, americium, and curiumm, although less studied, are also of importance in fully understanding the nuclear fuel engineering process and the safe geological disposal of radioactive wastes. PMID:22873132

  16. Thermodynamic study on the protonation of glycine in different (water + 1-butyl-3-methylimidazolium tetrafluoroborate) mixed solvents and ionic strengths

    International Nuclear Information System (INIS)

    Highlights: • Dependence of glycine protonation constants on ionic strength. • The ionic strength dependence has been modeled with the extended Debye–Hückel equation. • The ionic liquid behaves like a not significantly interacting salt for % IL > 20%. • Kamlet–Abboud–Taft solvatochromic regression coefficients. -- Abstract: The 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF4, is an ionic liquid when pure. The acid base properties of aqueous solutions of [bmim]BF4 were examined by potentiometric titration. Then, protonation constants of glycine in binary mixtures of water and [bmim]BF4 were determined, from potentiometric titration data obtained at T = 298.2 K and various ionic strengths of sodium chloride (0.25 ⩽ I ⩽ 1.00 mol · dm−3). The ionic strength dependence of the equilibrium constants of glycine was fitted to an extended Debye–Hückel equation to derive ionic strength dependence parameters. Comparison with literature data showed that, even at high concentrations, [bmim]BF4 is similar to the electrolyte [(C2H5)4NI], in that it does not interact significantly with other solutes. Solvatochromic parameters in the binary mixtures of water and [bmim]BF4 have been calculated by using Redlich–Kister equation. Kamlet–Abboud–Taft (KAT) solvatochromic equation allows us to determine the values of calculated protonation constants in different media

  17. MEMS Calculator

    Science.gov (United States)

    SRD 166 MEMS Calculator (Web, free access)   This MEMS Calculator determines the following thin film properties from data taken with an optical interferometer or comparable instrument: a) residual strain from fixed-fixed beams, b) strain gradient from cantilevers, c) step heights or thicknesses from step-height test structures, and d) in-plane lengths or deflections. Then, residual stress and stress gradient calculations can be made after an optical vibrometer or comparable instrument is used to obtain Young's modulus from resonating cantilevers or fixed-fixed beams. In addition, wafer bond strength is determined from micro-chevron test structures using a material test machine.

  18. Liquid-liquid miscibility and volumetric properties of aqueous solutions of ionic liquids as a function of temperature

    OpenAIRE

    Wang, Silu; Johan JACQUEMIN; Husson, Pascale; Hardacre, Christpher; Costa Gomes, Margarita F.

    2009-01-01

    The volumetric properties of seven {water + ionic liquid} binary mixtures have been studied as a function of temperature from (293 to 343) K. The phase behaviour of the systems was first investigated using a nephelometric method and excess molar volumes were calculated from densities measured using an Anton Paar densimeter and fitted using a Redlich-Kister type equation. Two ionic liquids fully miscible with water (1-butyl-3-methylimidazolium tetrafluoroborate ([CCIm][BF]) and 1-ethyl-3-methy...

  19. Simulation of Ionic Populations in Hot Dense Plasmas via a New Method beyond the Average Atom Model

    Institute of Scientific and Technical Information of China (English)

    WANG Min-Sheng; LIU Ling-Tao; LI Jia-Ming

    2005-01-01

    @@ In theoretical simulations and analysis of diagnostic measurements for hot dense plasmas in the inertial confinementfusion researches, it is usually necessary to consider thousands of transition arrays between a huge number of ionic energy states. Average atom models are adopted for practical purposes. In order to calculate ionic populations of hot dense plasmas more accurately either in local thermodynamic equilibrium or in non-local thermodynamic equilibrium conditions, a simple method beyond the AA model is proposed.

  20. Ionic liquid lubrication at electrified interfaces

    Science.gov (United States)

    Kong, Lingling; Huang, Wei; Wang, Xiaolei

    2016-06-01

    The lubrication performances of ionic liquids at electrified interfaces have been investigated by using a reciprocating sliding tribometer. Experimental results indicated that the lubricity of the confined ionic liquids was markedly affected by the application of external electric field and strong interface electric field strength could result in high friction. The influence was more pronounced for the ionic liquid with a shorter alkyl side chain in particular. The main reason of the friction increment might be ascribed to the electrically influenced surface adsorption where the charged ions were structured to form robust and ordered layers.

  1. Quantized friction across ionic liquid thin films.

    Science.gov (United States)

    Smith, Alexander M; Lovelock, Kevin R J; Gosvami, Nitya Nand; Welton, Tom; Perkin, Susan

    2013-10-01

    Ionic liquids - salts in the liquid state under ambient conditions - are of great interest as precision lubricants. Ionic liquids form layered structures at surfaces, yet it is not clear how this nano-structure relates to their lubrication properties. We measured the friction force between atomically smooth solid surfaces across ionic liquid films of controlled thickness in terms of the number of ion layers. Multiple friction-load regimes emerge, each corresponding to a different number of ion layers in the film. In contrast to molecular liquids, the friction coefficients differ for each layer due to their varying composition. PMID:23942943

  2. Energy consumption analysis for CO2 separation using imidazolium-based ionic liquids

    International Nuclear Information System (INIS)

    Highlights: • CO2 solubility in imidazolium-based ionic liquids was surveyed and evaluated. • CO2 absorption enthalpy was calculated based on thermodynamic model. • The effects of cation and anion on CO2 absorption enthalpy were discussed. • Energy consumption for a CO2 separation process was investigated. - Abstract: CO2 solubility in ionic liquids has been measured extensively in order to develop ionic liquid-based technology for CO2 separation. However, the energy consumption analysis has not been investigated well for such technology. In order to carry out the energy consumption analysis for CO2 separation using ionic liquids based on available experimental data, in this work, the experimental data of the CO2 solubility in imidazolium-based ionic liquids at pressures below 10 MPa was surveyed and evaluated by a semi-empirical thermodynamic model firstly. Based on the reliable experimental solubility data, the enthalpy of CO2 absorption was further calculated by the thermodynamic model. The results show that the CO2 absorption enthalpy in the studied ionic liquids is dominated by the enthalpy of CO2 dissolution and the contribution of excess enthalpy increases with increasing CO2 solubility in ionic liquids. The magnitude of the CO2 absorption enthalpy decreases with increasing chain length in cation and strongly depends on the anion of ionic liquids. Furthermore, the energy consumption for a CO2 separation process by pressure swing and/or temperature swing was investigated. For the pressure swing process, the Henry’s constant of CO2 in ionic liquids is an important factor for energy consumption analysis; If CO2 is absorbed at 298 K and 1 MPa and ionic liquid is regenerated by decreasing the pressure to 0.1 MPa at the same temperature, among the studied ionic liquids, [emim][EtSO4] is the solvent with the lowest energy consumption of 9.840 kJ/mol CO2. For the temperature swing process, the heat capacity of ionic liquids plays a more important role; If

  3. Ionization cross sections and ionic yield in an ion source with confined electron beam

    International Nuclear Information System (INIS)

    A new ion source for fully stripped ion production and polarized particles storage is studied. Ionization cross sections are simulated by the semi-empirical Loetz formula revised by Donets. The ionic yield of the ion source is calculated per pulse and second in the case of this source being used for a synchrocyclotron, a linear accelerator or a cyclotron

  4. A study of a fast ionic conductor AgI-CsI

    Energy Technology Data Exchange (ETDEWEB)

    Nalini, B. [Bharathiar Univ., Coimbatore (India). Dept. of Phys.; Selvasekarapandian, S. [Bharathiar Univ., Coimbatore (India). Dept. of Phys.; Janaki, K. [Bharathiar Univ., Coimbatore (India). Dept. of Phys.

    1996-09-01

    One molar ratio of the compound AgI-CsI has been taken for the ionic conductivity study. The activation energy has been obtained from the Arrhenius plot. The theory of Rice and Roth has been applied to calculate the number of potentially mobile ions of the conducting species. (orig.)

  5. Cooperative and non-linear phenomena at the neutral-ionic phase transition

    OpenAIRE

    Painelli, Anna; Del Freo, Luca; Soos, Zoltan G.

    2001-01-01

    The complex interplay among on-site energy, Hubbard U, and coupling to Holstein and Peierls phonons at the neutral-ionic phase transition is discussed using diagrammatic valence bond calculations. The charge transfer and dimerization amplitudes and the infrared intensity of molecular vibrations are studied in the transition region.

  6. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Directory of Open Access Journals (Sweden)

    Eero eSalminen

    2014-02-01

    Full Text Available The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat benzalkonium [ADBA] (alkyldimethylbenzylammonium was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs. Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC. The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  7. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Science.gov (United States)

    Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

    2014-02-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  8. Comparison between an ionic (Ioglicinate) and a non-ionic (Iohexol) contrast medium in renal CT

    International Nuclear Information System (INIS)

    A simple blind study (90 patients) was performed to compare a non-ionic contrast medium (Iohexol) at two concentration levels with an ionic contrast medium (Ioglicinate) in renal CT. In the excretory phase relevant to routine examination, the non-ionic contrast medium showed a significantly poorer imaging quality despite identical iodine content. This was due to interface artefacts at the pelvi-calyceal system caused by an elevated contrast urine concentration at reduced osmotic diuresis. (orig.)

  9. Comparison between an ionic (Ioglicinate) and a non-ionic (Iohexol) contrast medium in renal CT

    Energy Technology Data Exchange (ETDEWEB)

    Weigert, F.; Hartmann, A.; Rohde, U.

    1986-05-01

    A simple blind study (90 patients) was performed to compare a non-ionic contrast medium (Iohexol) at two concentration levels with an ionic contrast medium (Ioglicinate) in renal CT. In the excretory phase relevant to routine examination, the non-ionic contrast medium showed a significantly poorer imaging quality despite identical iodine content. This was due to interface artefacts at the pelvi-calyceal system caused by an elevated contrast urine concentration at reduced osmotic diuresis.

  10. Reliability Calculations

    DEFF Research Database (Denmark)

    Petersen, Kurt Erling

    1986-01-01

    probabilistic approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis...... of very complex systems. In order to increase the applicability of the programs variance reduction techniques can be applied to speed up the calculation process. Variance reduction techniques have been studied and procedures for implementation of importance sampling are suggested....

  11. Ionic liquid polyoxometalates as light emitting materials

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-acosta, Denisse [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Scott, Brian [Los Alamos National Laboratory; Bennett, Bryan L [Los Alamos National Laboratory; Purdy, Geraldine M [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Mc Kigney, Edward [Los Alamos National Laboratory; Gilbertson, Robert [Los Alamos National Laboratory

    2008-01-01

    The low melting point, negligible vapor pressure, good solubility, and thermal and chemical stability make ionic liquids useful materials for a wide variety of applications. Polyoxometalates are early transition metal oxygen clusters that can be synthesized in many different sizes and with a variety of heterometals. The most attractive feature of POMs is that their physical properties, in particular electrical, magnetic, and optical properties, can be easily modified following known procedures. It has been shown that POMs can exhibit cooperative properties, as superconductivity and energy transfer. POM ionic liquids can be obtained by selecting the appropliate cation. Different alkyl ammonium and alkyl phosphonium salts are being used to produce new POM ionic liquids together with organic or inorganic luminescent centers to design light emitting materials. Ammonium and phosphonium cations with activated, polymerizable groups are being used to further polymerize the ionic liquid into transparent, solid materials with high metal density.

  12. Ionic Liquid Epoxy Composite Cryotanks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this work is to determine the optimal process for manufacturing lightweight linerless cryogenic storage tanks using ionic liquid epoxy composite...

  13. Ionic liquid-nanoparticle hybrid electrolytes

    KAUST Repository

    Lu, Yingying

    2012-01-01

    We investigate physical and electrochemical properties of a family of organic-inorganic hybrid electrolytes based on the ionic liquid 1-methyl-3-propylimidazolium bis(trifluoromethanesulfone) imide covalently tethered to silica nanoparticles (SiO 2-IL-TFSI). The ionic conductivity exhibits a pronounced maximum versus LiTFSI composition, and in mixtures containing 13.4 wt% LiTFSI, the room-temperature ionic conductivity is enhanced by over 3 orders of magnitude relative to either of the mixture components, without compromising lithium transference number. The SiO 2-IL-TFSI/LiTFSI hybrid electrolytes are thermally stable up to 400°C and exhibit tunable mechanical properties and attractive (4.25V) electrochemical stability in the presence of metallic lithium. We explain these observations in terms of ionic coupling between counterion species in the mobile and immobile (particle-tethered) phases of the electrolytes. © 2012 The Royal Society of Chemistry.

  14. Selective gas absorption by ionic liquids

    DEFF Research Database (Denmark)

    Shunmugavel, Saravanamurugan; Kegnæs, Søren; Due-Hansen, Johannes;

    2010-01-01

    Reversible absorption performance for the flue gas components CO 2, NO and SO2 has been tested for several different ionic liquids (ILs) at different temperatures and flue gas compositions. Furthermore, different porous, high surface area carriers have been applied as supports for the ionic liquids...... to obtain Supported Ionic Liquid-Phase (SILP) absorber materials. The use of solid SILP absorbers with selected ILs were found to significantly improve the absorption capacity and sorption dynamics at low flue gas concentration, thus making the applicability of ILs viable in technical, continuous flow...... processes for flue gas cleaning. The results show that CO 2, NO and SO2 can be reversible and selective absorbed using different ILs and that Supported Ionic Liquid-Phase (SILP) absorbers are promising materials for industrial flue gas cleaning. Absorption/desorption dynamics can be tuned by temperatures...

  15. Thermodynamic Properties of Caprolactam Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    JIANG Lu; BAI Liguang; ZHU Jiqin; CHEN Biaohua

    2013-01-01

    A series of caprolactam ionic liquids (ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter (DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.

  16. Study of thioglycosylation in ionic liquids

    Directory of Open Access Journals (Sweden)

    Ragauskas Arthur

    2006-06-01

    Full Text Available Abstract A novel, green chemistry, glycosylation strategy was developed based upon the use of ionic liquids. Research studies demonstrated that thiomethyl glycosides could readily be activated with methyl trifluoromethane sulfonate, using 1-butyl-3-methylimidazolium tetrafluoroborate as a solvent. This green chemistry glycosylation strategy provided disaccharides with typical yields averaging 75%. The ionic liquid solvent could be readily reused for five sequential glycosylation reactions with no impact on product yield.

  17. Lanthanides and actinides in ionic liquids

    OpenAIRE

    Binnemans, Koen

    2007-01-01

    This lecture gives an overview of the research possibilities offered by combining f-elements (lanthanides and actinides) with ionic liquids [1] Many ionic liquids are solvents with weakly coordinating anions. Solvation of lanthanide and actinide ions in these solvents is different from what is observed in conventional organic solvents and water. The poorly solvating behavior can also lead to the formation of coordination compounds with low coordination numbers. The solvation of f-elements can...

  18. Ionic liquids behave as dilute electrolyte solutions

    OpenAIRE

    Gebbie, Matthew A.; Valtiner, Markus; Banquy, Xavier; Fox, Eric T.; Henderson, Wesley A.; Israelachvili, Jacob N.

    2013-01-01

    We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force–distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical contr...

  19. Dynamics of Ion Transport in Ionic Liquids

    OpenAIRE

    Lee, Alpha A.; Kondrat, Svyatoslav; Vella, Dominic; Goriely, Alain

    2015-01-01

    A gap in understanding the link between continuum theories of ion transport in ionic liquids and the underlying microscopic dynamics has hindered the development of frameworks for transport phenomena in these concentrated electrolytes. Here, we construct a continuum theory for ion transport in ionic liquids by coarse graining a simple exclusion process of interacting particles on a lattice. The resulting dynamical equations can be written as a gradient flow with a mobility matrix that vanishe...

  20. Ionic liquid gel materials: applications in green and sustainable chemistry

    OpenAIRE

    Marr, Patricia C.; Marr, Andrew C.

    2016-01-01

    Ionic liquid gel materials offer a way to further utilise ionic liquids in technological applications. Combining the controlled and directed assembly of gels, with the diverse applications of ionic liquids, enables the design of a heady combination of functional tailored materials, leading to the development of task specific / functional ionic liquid gels. This review introduces gels and gel classification, focusing on ionic liquid gels and their potential roles in a more sustainable future. ...

  1. Task-specific ionic liquids for solubilizing metal compounds

    OpenAIRE

    Thijs, Ben

    2007-01-01

    The main goal of this PhD thesis was to design new task-specific ionic liquids with the ability to dissolve metal compounds. Despite the large quantity of papers published on ionic liquids, not much is known about the mechanisms of dissolving metals in ionic liquids or about metal-containing ionic liquids. Additionally, many of the commercially available ionic liquids exhibit a very limited solubilizing power for metal compounds, although this is for many applications like electrodeposition a...

  2. The structure of ionic liquids

    CERN Document Server

    Gontrani, Lorenzo

    2014-01-01

    This volume describes the most recent findings on the structure of ILs interpreted through cutting-edge experimental and theoretical methods. Research in the field of ionic liquids (ILs) keeps a fast and steady pace. Since these new-generation molten salts first appeared in the chemistry and physics landscape, a large number of new compounds has been synthesized. Most of them display unexpected behaviour and possess stunning properties. The coverage in this book ranges from the mesoscopic structure of ILs to their interaction with proteins. The reader will learn how diffraction techniques (small and large angle X-Ray and neutron scattering, powder methods), X-Ray absorption spectroscopies (EXAFS/XANES), optical methods (IR, RAMAN), NMR and calorimetric methods can help the study of ILs, both as neat liquids and in mixtures with other compounds. It will enable the reader to choose the best method to suit their experimental needs. A detailed survey of theoretical methods, both quantum-chemical and classical, ...

  3. Anomalous Wien Effects in Supercooled Ionic Liquids

    Science.gov (United States)

    Patro, L. N.; Burghaus, O.; Roling, B.

    2016-05-01

    We have measured conductivity spectra of several supercooled monocationic and dicationic ionic liquids in the nonlinear regime by applying ac electric fields with large amplitudes up to about 180 kV /cm . Thereby, higher harmonic ac currents up to the 7th order were detected. Our results point to the existence of anomalous Wien effects in supercooled ionic liquids. Most ionic liquids studied here exhibit a conductivity-viscosity relation, which is close to the predictions of the Nernst-Einstein and Stokes-Einstein equations, as observed for classical strong electrolytes like KCl. These "strong" ionic liquids show a much stronger nonlinearity of the conductivity than classical strong electrolytes. On the other hand, the conductivity-viscosity relation of the ionic liquid [P6 ,6 ,6 ,14][Cl ] points to ion association effects. This "weak" ionic liquid shows a strength of the nonlinear effect, which is comparable to classical weak electrolytes. However, the nonlinearity increases quadratically with the field. We suggest that a theory for explaining these anomalies will have to go beyond the level of Coulomb lattice gas models.

  4. Anomalous Wien Effects in Supercooled Ionic Liquids.

    Science.gov (United States)

    Patro, L N; Burghaus, O; Roling, B

    2016-05-01

    We have measured conductivity spectra of several supercooled monocationic and dicationic ionic liquids in the nonlinear regime by applying ac electric fields with large amplitudes up to about 180  kV/cm. Thereby, higher harmonic ac currents up to the 7th order were detected. Our results point to the existence of anomalous Wien effects in supercooled ionic liquids. Most ionic liquids studied here exhibit a conductivity-viscosity relation, which is close to the predictions of the Nernst-Einstein and Stokes-Einstein equations, as observed for classical strong electrolytes like KCl. These "strong" ionic liquids show a much stronger nonlinearity of the conductivity than classical strong electrolytes. On the other hand, the conductivity-viscosity relation of the ionic liquid [P_{6,6,6,14}][Cl] points to ion association effects. This "weak" ionic liquid shows a strength of the nonlinear effect, which is comparable to classical weak electrolytes. However, the nonlinearity increases quadratically with the field. We suggest that a theory for explaining these anomalies will have to go beyond the level of Coulomb lattice gas models. PMID:27203333

  5. Ion Specificity and Micellization of Ionic Surfactants: A Monte Carlo Study

    CERN Document Server

    Santos, Alexandre P dos; Levin, Yan

    2014-01-01

    We develop a simulation method which allows us to calculate the critical micelle concentrations for ionic surfactants in the presence of different salts. The results are in good agreement with the experimental data. The simulations are performed on a simple cubic lattice. The anionic interactions with the alkyl chains are taken into account based on the previously developed theory of the interfacial tensions of hydrophobic interfaces: the kosmotropic anions do not interact with the hydrocarbon tails of ionic surfactants, while chaotropic anions interact with the alkyl chains through a dispersion potential proportional to the anionic polarizability.

  6. A rapid method for the evaluation of the ionic permeabilities across epithelial cell membranes.

    Science.gov (United States)

    Movileanu, L

    1999-02-01

    This short note presents a recipe for the calculation of the ionic permeabilities across epithelial cell membranes. The method requires the Goldman-Hodgkin-Katz formalism as well as the consideration of the equivalent electrical circuit for an epithelial cell. The equivalent electrical circuit is solved in terms of the equivalent electromotive forces coupled in series with the ionic resistances of both cell membranes (apical and basolateral). The present procedure is feasible for any leaky epithelial cell membrane with the condition that this membrane (apical or basolateral) does not contain primary or secondary mechanisms for active transport. PMID:10100952

  7. Transport properties of room temperature ionic liquids from classical molecular dynamics

    CERN Document Server

    Andreussi, Oliviero

    2012-01-01

    Room Temperature Ionic Liquids (RTILs) have attracted much of the attention of the scientific community in the past decade due the their novel and highly customizable properties. Nonetheless their high viscosities pose serious limitations to the use of RTILs in practical applications. To elucidate some of the physical aspects behind transport properties of RTILs, extensive classical molecular dynamics (MD) calculations are reported. Bulk viscosities and ionic conductivities of butyl-methyl-imidazole based RTILs are presented over a wide range of temperatures. The dependence of the properties of the liquids on simulation parameters, e.g. system size effects and choice of the interaction potential, is analyzed.

  8. A computer program for external modes in complex ionic crystals (the rigid molecular-ion model)

    International Nuclear Information System (INIS)

    A computer program DISPR has been developed to calculate the external mode phonon dispersion relation in the harmonic approximation for complex ionic crystals using the rigid molecular ion model. A description of the program, the flow diagram and the required input information are given. A sample calculation for α-KNO3 is presented. The program can handle any type of crystal lattice with any number of atoms and molecules per unit cell with suitable changes in dimension statements. (M.G.B.)

  9. (Liquid + liquid) equilibria of perfluorocarbons with fluorinated ionic liquids

    International Nuclear Information System (INIS)

    Highlights: • (Liquid + liquid) equilibria perfluorocarbons and fluorinated ionic liquids. • Non-Random Two Liquid model was successfully applied. • Thermodynamic functions that describe the solvation process were calculated. -- Abstract: In order to evaluate the feasibility of partially replace perfluorocarbons (PFCs) with fluorinated ionic liquids (FILs) in PFCs-in-water emulsions, usually used for biomedical purposes, herein the (liquid + liquid) phase equilibria of FILs containing fluorinated chains longer than four carbons with PFCs were carried out in a wide range of temperatures. With this goal in mind, two PFCs (perfluorooctane and perfluorodecalin) were selected and the (liquid + liquid) equilibria of the binary mixtures of these PFCs and FILs were studied at atmospheric pressure in a temperature range from T (293.15 to 343.15) K. For these studies, FILs containing ammonium, pyridinium and imidazolium cations and different anions with fluorocarbon alkyl chains between 4 and 8 were included. Additionally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the PFCs + FILs binary mixtures. Moreover, thermodynamic functions that describe the solvation process were calculated from the experimental data

  10. On the theory of ionic solutions.

    Science.gov (United States)

    Olivares, W; McQuarrie, D A

    1975-02-01

    One of the purposes of this paper is to assess the degree of applicability of the nonlinear Poisson-Boltzmann equation. In order to do this we compare the thermodynamic properties calculated through this equation with Monte Carlo data on 1-1 and 2-2 electrolytes described by the restricted primitive model, in which the ions are modeled by hard spheres with a coulombic potential and the solvent is modeled as a continuum dielectric medium of uniform dielectric constant epsilon. We choose Monte Carlo data rather than real experimental data since all parameters are completely specified and there is no liberty for "adjustment." Thus this serves as a definitive test. In addition, we present a simple but numerically accurate alternative approximation scheme which is not only numerically superior to the Poisson-Boltzmann equation but avoids the necessity of solving a nonlinear partial differential equation which is approximate in the first place. The new approximation scheme that is presented here is suggested by recent developments in the statistical mechanical theories of ionic solutions which are reviewed in the Introduction. Although these theories themselves yield exceedingly good comparison with experimental (Monte Carlo) data, they involve fairly advanced theoretical and mathematical techniques and do not appear to be readily solvable for other than very simple geometries. The two approximations suggested here require only the solution of the linear Debye-Hückel equation, which has been solved for a variety of systems. These two approximations are simple to apply and yield good thermodynamic properties up to concentrations of 2 M for the restricted primitive model. In addition, they have a sound theoretical foundation and are offered as a substitute for the difficult-to-solve nonlinear Poisson-Boltzmann equation. PMID:1111632

  11. SPEI Calculator

    OpenAIRE

    Beguería, Santiago; Vicente Serrano, Sergio M.

    2009-01-01

    [EN] *Objectives: The program calculates time series of the Standardised Precipitation-Evapotransporation Index (SPEI). *Technical Characteristics: The program is executed from the Windows console. From an input data file containing monthly time series of precipitation and mean temperature, plus the geographic coordinates of the observatory, the program computes the SPEI accumulated at the time interval specified by the user, and generates a new data file with the SPEI time serie...

  12. Burnout calculation

    International Nuclear Information System (INIS)

    Reviewed is the effect of heat flux of different system parameters on critical density in order to give an initial view on the value of several parameters. A thorough analysis of different equations is carried out to calculate burnout is steam-water flows in uniformly heated tubes, annular, and rectangular channels and rod bundles. Effect of heat flux density distribution and flux twisting on burnout and storage determination according to burnout are commended

  13. Effective Potential and Interdiffusion in Binary Ionic Mixtures

    CERN Document Server

    Beznogov, M V

    2014-01-01

    We calculate interdiffusion coefficients in a two-component, weakly or strongly coupled ion plasma (gas or liquid, composed of two ion species immersed into a neutralizing electron background). We use an effective potential method proposed recently by Baalrud and Daligaut [PRL, 110, 235001, (2013)]. It allows us to extend the standard Chapman-Enskog procedure of calculating the interdiffusion coefficients to the case of strong Coulomb coupling. We compute binary diffusion coefficients for several ionic mixtures and fit them by convenient expressions in terms of the generalized Coulomb logarithm. These fits cover a wide range of plasma parameters spanning from weak to strong Coulomb couplings. They can be used to simulate diffusion of ions in ordinary stars as well as in white dwarfs and neutron stars.

  14. Quality Control of 1-Alkyl-3-methylimidazolium Ionic Liquid Precursors with HPLC

    Institute of Scientific and Technical Information of China (English)

    张延强; 张建敏; 陈玉涣; 张锁江

    2007-01-01

    A high performance liquid chromatography (HPLC) method was proposed to monitor the synthesis and purification of the 1-alkyl-3-methylimidazolium ionic liquid precursors from alkylation of 1-methylimidazole with alkyl halides and determine the purity of final products. The results showed that separation of 1-methylimidazole from the precursors could be obtained under the HPLC performance conditions such as cation exchange column, acetonitrile/KH2PO4 aqueous solution and 209 nm wavelength. The content of unreacted 1-methylimidazole in the precursors could be easily calculated from their corresponding HPLC peak areas with the calibration curve of 1-methylimidazole. The retention times of the 1-alkyl-3-methylimidazolium ionic liquid precursors decreased with their increasing alkyls, and the ionic liquids with the same cation and different anions had almost the same retention times.

  15. Mean ionic activity coefficients in aqueous NaCl solutions from molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Mester, Zoltan; Panagiotopoulos, Athanassios Z., E-mail: azp@princeton.edu [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-01-28

    The mean ionic activity coefficients of aqueous NaCl solutions of varying concentrations at 298.15 K and 1 bar have been obtained from molecular dynamics simulations by gradually turning on the interactions of an ion pair inserted into the solution. Several common non-polarizable water and ion models have been used in the simulations. Gibbs-Duhem equation calculations of the thermodynamic activity of water are used to confirm the thermodynamic consistency of the mean ionic activity coefficients. While the majority of model combinations predict the correct trends in mean ionic activity coefficients, they overestimate their values at high salt concentrations. The solubility predictions also suffer from inaccuracies, with all models underpredicting the experimental values, some by large factors. These results point to the need for further ion and water model development.

  16. Mean ionic activity coefficients in aqueous NaCl solutions from molecular dynamics simulations

    International Nuclear Information System (INIS)

    The mean ionic activity coefficients of aqueous NaCl solutions of varying concentrations at 298.15 K and 1 bar have been obtained from molecular dynamics simulations by gradually turning on the interactions of an ion pair inserted into the solution. Several common non-polarizable water and ion models have been used in the simulations. Gibbs-Duhem equation calculations of the thermodynamic activity of water are used to confirm the thermodynamic consistency of the mean ionic activity coefficients. While the majority of model combinations predict the correct trends in mean ionic activity coefficients, they overestimate their values at high salt concentrations. The solubility predictions also suffer from inaccuracies, with all models underpredicting the experimental values, some by large factors. These results point to the need for further ion and water model development

  17. Mean ionic activity coefficients in aqueous NaCl solutions from molecular dynamics simulations.

    Science.gov (United States)

    Mester, Zoltan; Panagiotopoulos, Athanassios Z

    2015-01-28

    The mean ionic activity coefficients of aqueous NaCl solutions of varying concentrations at 298.15 K and 1 bar have been obtained from molecular dynamics simulations by gradually turning on the interactions of an ion pair inserted into the solution. Several common non-polarizable water and ion models have been used in the simulations. Gibbs-Duhem equation calculations of the thermodynamic activity of water are used to confirm the thermodynamic consistency of the mean ionic activity coefficients. While the majority of model combinations predict the correct trends in mean ionic activity coefficients, they overestimate their values at high salt concentrations. The solubility predictions also suffer from inaccuracies, with all models underpredicting the experimental values, some by large factors. These results point to the need for further ion and water model development. PMID:25637995

  18. Method for estimating ionicities of oxides using O1s photoelectron spectra

    International Nuclear Information System (INIS)

    The average valence, ValO, of the oxygen anions in the perovskite oxide BaTiO3, was found using O1s photoelectron spectra to be −1.55. This experimental result is close to the theoretical value for BaTiO3 (−1.63) calculated by Cohen [Nature 358, 136 (1992)] using density functional theory. Using the same approach, we obtained values of ValO for several monoxides, and investigated the dependence of ValO and the ionicity on the second ionization energy, V(M2+), of the metal cation. We found that the dependence of the ionicity on V(M2+) in this work is close to that reported by Phillips [Rev. Mod. Phys. 42, 317 (1970)]. We therefore suggest that O1s photoelectron spectrum measurements should be accepted as a general experimental method for estimating the ionicity and average valence of oxygen anions

  19. Ionic liquids--an overview.

    Science.gov (United States)

    Jenkins, Harry Donald Brooke

    2011-01-01

    A virtually unprecedented exponential burst of activity resulted following the publication, in 1998, of an article by Michael Freeman (Freemantle, M. Chemical & Engineering News, 1998, March 30, 32), which speculated on the role and contribution that ionic liquids (ILs) might make in the future on the development of clean technology. Up until that time only a handful of researchers were routinely engaged in the study of ILs but frenzied activity followed that continues until the present day. Scientists from all disciplines related to Chemistry have now embarked on studies, including theoreticians who are immersed in the aim of improving the "designer role" so that they can tailor ILs to deliver specified properties. This article, whilst not in any sense attempting to be exhaustive, highlights the main features which characterise ILs, presenting these in a form readily assimilated by newcomers to this area of research. An extensive glossary is featured in this article as well as a chronological list which charts the major areas of development. What follows consists of a number of sections briefly describing the role of lLs as solvents, hypergolic fuels, their use in some electrochemical devices such as solar cells and lithium batteries and their use in polymerisation reactions, followed by a concise summary of some of the other roles that they are capable of playing. The role of empirical, volume-based thermodynamics procedures, as well as large scale computational studies on ILs is also highlighted. These developments which are described are remarkable in that they have been achieved in less than a decade and a half although knowledge of these materials has existed for much longer. PMID:22026149

  20. Teleportation of Multi-ionic GHZ States and Arbitrary Bipartite Ionic State via Linear Optics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We present a scheme for teleportation of multi-ionic GHZ states and arbitrary bipartite ionic state only by single-qubit measurements via linear optical elements. In our scheme, we avoid the difficulty of joint measurement and synchronizing the arrival time of the two scattered photons, which are faced by previous schemes. So our scheme can be realized easily within current experimental technology.

  1. Study of thermodynamic and transport properties of phosphonium-based ionic liquids

    International Nuclear Information System (INIS)

    Highlights: ► Physical and transport properties of three hydrophilic phoshonium ILs were determined. ► Experimental density, viscosity, refractive index and speed of sound were correlated. ► Predictive equations were successfully employed to predict density of the three ILs. -- Abstract: In this work, the experimental values of density, speed of sound, refractive index and dynamic viscosity have been obtained from T = (293.15 to 343.15) K for the three phosphonium-based ionic liquids: tributyl methyl phoshponium methylsulfate (P4441 C1SO4), tributyl ethyl phosphonium diethylphosphate (P4442 (C2)2PO4) and tributyl octyl phosphonium chloride (P4448 Cl). The isentropic compressibility has been calculated by means of the Laplace equation from the experimental speed of sound results for the three ionic liquids at different temperatures. Density, speed of sound, refractive index and isentropic compressibility have been correlated by polynomial equations. The Lorentz–Lorenz, Dale–Gladstone, Eykman, Oster, Arago–Biot, Newton and modified Eykman equations were the empirical models used to correlate satisfactorily the relationship between the densities and refractive indices of the ionic liquids selected. The temperature dependence of the experimental dynamic viscosities for the ionic liquids selected can be described by an Arrhenius-like law and by VFT equations. The Riedel, Narsimham, Bradford–Thodos, Yen–Woods, Rackett, Spencer–Danner, Gunn–Yamada, Hankinson–Thomson (COSTALD model), VSY, VSD, MH and LGM equations were employed to predict the densities of the pure ionic liquids

  2. Influence of ionic strength on the surface charge and interaction of layered silicate particles.

    Science.gov (United States)

    Liu, Jing; Miller, Jan D; Yin, Xihui; Gupta, Vishal; Wang, Xuming

    2014-10-15

    The surface charge densities and surface potentials of selected phyllosilicate surfaces were calculated from AFM surface force measurements and reported as a function of ionic strength at pH 5.6. The results show that the silica faces of clay minerals follow the constant surface charge model because of isomorphous substitution in the silica tetrahedral layer. A decreasing surface charge density sequence was observed as follows: muscovite silica face>kaolinite silica face>talc silica face, which is expected to be due to the extent of isomorphous substitution. In contrast, at pH 5.6, the alumina face and the edge surface of kaolinite follow the constant surface potential model with increasing ionic strength, and the surface charge density increased with increasing ionic strength. The cluster size of suspended kaolinite particles at pH 5.6 was found to increase with increasing ionic strength due to an increase in the surface charge density for the alumina face and the edge surface. However, the cluster size decreased at 100mM KCl as a result of an unexpected decrease in the surface charge of the alumina face. When the ionic strength continued to increase above 100mM KCl, the van der Waals attraction dominated and larger clusters of micron size were stabilized. PMID:25086721

  3. Calculator calculus

    CERN Document Server

    McCarty, George

    1982-01-01

    How THIS BOOK DIFFERS This book is about the calculus. What distinguishes it, however, from other books is that it uses the pocket calculator to illustrate the theory. A computation that requires hours of labor when done by hand with tables is quite inappropriate as an example or exercise in a beginning calculus course. But that same computation can become a delicate illustration of the theory when the student does it in seconds on his calculator. t Furthermore, the student's own personal involvement and easy accomplishment give hi~ reassurance and en­ couragement. The machine is like a microscope, and its magnification is a hundred millionfold. We shall be interested in limits, and no stage of numerical approximation proves anything about the limit. However, the derivative of fex) = 67.SgX, for instance, acquires real meaning when a student first appreciates its values as numbers, as limits of 10 100 1000 t A quick example is 1.1 , 1.01 , 1.001 , •••• Another example is t = 0.1, 0.01, in the functio...

  4. Reliability calculations

    International Nuclear Information System (INIS)

    Risk and reliability analysis is increasingly being used in evaluations of plant safety and plant reliability. The analysis can be performed either during the design process or during the operation time, with the purpose to improve the safety or the reliability. Due to plant complexity and safety and availability requirements, sophisticated tools, which are flexible and efficient, are needed. Such tools have been developed in the last 20 years and they have to be continuously refined to meet the growing requirements. Two different areas of application were analysed. In structural reliability probabilistic approaches have been introduced in some cases for the calculation of the reliability of structures or components. A new computer program has been developed based upon numerical integration in several variables. In systems reliability Monte Carlo simulation programs are used especially in analysis of very complex systems. In order to increase the applicability of the programs variance reduction techniques can be applied to speed up the calculation process. Variance reduction techniques have been studied and procedures for implementation of importance sampling are suggested. (author)

  5. Water Contaminant Mitigation in Ionic Liquid Propellant

    Science.gov (United States)

    Conroy, David; Ziemer, John

    2009-01-01

    Appropriate system and operational requirements are needed in order to ensure mission success without unnecessary cost. Purity requirements applied to thruster propellants may flow down to materials and operations as well as the propellant preparation itself. Colloid electrospray thrusters function by applying a large potential to a room temperature liquid propellant (such as an ionic liquid), inducing formation of a Taylor cone. Ions and droplets are ejected from the Taylor cone and accelerated through a strong electric field. Electrospray thrusters are highly efficient, precise, scaleable, and demonstrate low thrust noise. Ionic liquid propellants have excellent properties for use as electrospray propellants, but can be hampered by impurities, owing to their solvent capabilities. Of foremost concern is the water content, which can result from exposure to atmosphere. Even hydrophobic ionic liquids have been shown to absorb water from the air. In order to mitigate the risks of bubble formation in feed systems caused by water content of the ionic liquid propellant, physical properties of the ionic liquid EMI-Im are analyzed. The effects of surface tension, material wetting, physisorption, and geometric details of the flow manifold and electrospray emitters are explored. Results are compared to laboratory test data.

  6. Ionic Liquid Extractions of Soil Organic Matter

    Science.gov (United States)

    Patti, Antonio; Macfarlane, Douglas; Clarke, Michael

    2010-05-01

    A large range of ionic liquids with the ability to dissolve different classes of natural biopolymers (e.g. cellulose, lignin, protein) have been reported in the literature. These have the potential to isolate different fractions of soil organic matter, thus yielding novel information that is not available through other extraction procedures. The ionic liquids dimethylammonium dimethylcarbamate (DIMCARB), alkylbenzenesulfonate and 1-butyl-3methylimidazolium chloride (Bmim Cl) can solubilise selected components of soil organic matter. Soil extractions with these materials showed that the organic matter recovered showed chemical properties that were consistent with humic substances. These extracts had a slightly different organic composition than the humic acids extracted using the traditional International Humic Substances Society (IHSS) method. The ionic liquids also solubilised some inorganic matter from the soil. Humic acids recovered with alkali were also partially soluble in the ionic liquids. DIMCARB appeared to chemically interfere with organic extract, increasing the level of nitrogen in the sample. It was concluded that the ionic liquid Bmim Cl may function as a useful solvent for SOM, and may be used to recover organic matter of a different character to that obtained with alkali

  7. Full configuration-interaction study of the ionic-neutral curve crossing in LiF

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1988-01-01

    Full configuration-interaction (FCI) calculations are used to assess the relative ability of methods for truncating the n-particle expansion in describing the ionic-neutral curve crossing between the two lowest Sigma(+) states of LiF. While the FCI calculations yield a smooth dipole moment function, MRCI calculations based on CASSCF orbitals optimized for the lowest state at all r values yield a discontinuous dipole moment function. However, when the orbitals are optimized using a state-averaged CASSCF procedure, with equal weights for the ionic and neutral solutions, both the CASSCF and MRCI dipole moment functions are smooth and in reasonable agreement with the FCI. No single-reference-based method is found to work satisfactorily. Potential curves for the lowest two Sigma(+) states are determined in both the adiabatic and diabatic representations using a large atomic natural orbit Gaussian basis set and a state-averaged CASSCF/MRCI treatment of electron correlation.

  8. Thermodynamic study of the surface of liquid mixtures containing pyridinium-based ionic liquids and alkanols

    International Nuclear Information System (INIS)

    Highlights: • Surface tensions of a pyridinium ionic liquid with an alkanol have been determined. • From experimental data surface tension deviations have been obtained and correlated. • Relative adsorptions of alkanol at the (air + liquid) interface were also calculated. • The relative adsorptions were found positive in all the mixtures. - Abstract: Surface tension for seven binary mixtures containing a pyridinium-based ionic liquid (1-propylpyridinium tetrafluoroborate, 1-butylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, or 1-butyl-4-methylpyridinium) and a short chain alkanol (methanol or ethanol) were determined at the temperatures: (293.15, 303.15, 313.15, and 323.15) K. From these data, the surface tension deviations were calculated. These deviations were correlated using a Redlich–Kister polynomial expansion. Moreover, relative adsorptions of alkanol at the (air + liquid) interface were calculated from the Gibbs isotherm

  9. A ionic model for molecular units in molten aluminium trichloride and alkali chloroaluminates

    International Nuclear Information System (INIS)

    A simple ionic model including anion polarizability is developed for the Al2Cl6 molecular dimer and is tested against data on bond lengths, bond angles and vibrational frequencies from experiment and from molecular orbital calculations. The transferability of the model is tested through calculations of structure and vibrational frequencies for the (AlCl4)- and (Al2Cl7)- molecular ions as well as for related ionic clusters, the results being compared with available data. Further calculations are reported showing that the Al2Cl6 dimer is strongly stable against fluctuations into ionized states, the fluctuations examined being chlorine exchange between neighbouring dimers and the appearance of ionized products at intermediate stages in the dissociation of the dimer into neutral monomers. The relevance of the results to theoretical understanding of molten chloroaluminates in the acidic range up to pure molten AlCl3 is discussed. (author). 40 refs, 3 figs, 6 tabs

  10. Microfield in a dense plasma and highly charged ion Stark profile calculation

    International Nuclear Information System (INIS)

    In most laser compression experiments up to day, Stark broadening appears as the principal diagnostic method (density-temperature determination). The Stark line calculation needs the ionic microfield distribution; so the different plasma parameter influence on it must be known: density, temperature, ion charge and ion proportion in mixtures. These different questions are tackled; electronic (high frequency) and ionic (low frequency) components are studied separately. Dense plasma effects are in chapter I. Influence of diffraction quantum effects is studied in chapter II. Systems with many multicharged ionic components are studied in chapter III. And in chapter IV applications to Lyman α and Lyman β line calculation are presented for hydrogenoid ions

  11. The Research Progress of CO2 Capture with Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    赵志军; 董海峰; 张香平

    2012-01-01

    Due to their negligible volatility, reasonable thermal stability, strong dissolubility, wide liquid range and tunability of structure and property, ionic liquids have been regarded as emerging candidate reagents for CO2 cap- ture from industries gases. In this review, the research progresses in CO2 capture using conventional ionic liquids,functionalized ionic liquids, supported ionic-liquids membranes, polymerized ionic liquids and mixtures of ionic liquids with some molecular solvents were investigated and reviewed. Discussion of relevant research fields was presented and the future developments were suggested.

  12. Static dielectric properties of dense ionic fluids.

    Science.gov (United States)

    Zarubin, Grigory; Bier, Markus

    2015-05-14

    The static dielectric properties of dense ionic fluids, e.g., room temperature ionic liquids (RTILs) and inorganic fused salts, are investigated on different length scales by means of grandcanonical Monte Carlo simulations. A generally applicable scheme is developed which allows one to approximately decompose the electric susceptibility of dense ionic fluids into the orientation and the distortion polarization contribution. It is shown that at long range, the well-known plasma-like perfect screening behavior occurs, which corresponds to a diverging distortion susceptibility, whereas at short range, orientation polarization dominates, which coincides with that of a dipolar fluid of attached cation-anion pairs. This observation suggests that the recently debated interpretation of RTILs as dilute electrolyte solutions might not be simply a yes-no-question but it might depend on the considered length scale. PMID:25978895

  13. Individual SWCNT based ionic field effect transistor

    Science.gov (United States)

    Pang, Pei; He, Jin; Park, Jae Hyun; Krstic, Predrag; Lindsay, Stuart

    2011-03-01

    Here we report that the ionic current through a single-walled carbon nanotube (SWCNT) can be effectively gated by a perpendicular electrical field from a top gate electrode, working as ionic field effect transistor. Both our experiment and simulation confirms that the electroosmotic current (EOF) is the main component in the ionic current through the SWCNT and is responsible for the gating effect. We also studied the gating efficiency as a function of solution concentration and pH and demonstrated that the device can work effectively in the physiological relevant condition. This work opens the door to use CNT based nanofluidics for ion and molecule manipulation. This work was supported by the DNA Sequencing Technology Program of the National Human Genome Research Institute (1RC2HG005625-01, 1R21HG004770-01), Arizona Technology Enterprises and the Biodesign Institute.

  14. Synthesis and characterization of new ionic liquids

    International Nuclear Information System (INIS)

    In recent years, ionic liquids have been highlighted for its potential in various industrial applications. Among them, the salts of Broensted has a promising profile for the low toxicity, low cost and simple synthesis. This paper presents the synthesis and characterization of new salts of Bronsted with branched (lactate) or large chain anions (oleate) for future use as additives promoters of proton conductivity in fuel cells of ethanol. Experimental data were measured for density, sound velocity and conductivity of pure ionic liquids and mixtures. The density decreases linearly with increasing temperature, and sound velocity shows a similar trend, but not linear. The conductivity increases according to the Arrhenius model with activation energy less than 10 J/mol. Tests NMR, FTIR and TGA confirm ionic structure and thermal stability up to 165 deg C. (author)

  15. BWR radiation buildup control with ionic zinc

    International Nuclear Information System (INIS)

    In 1983 a hypothesis was disclosed which suggested that the presence of ionic zinc in the reactor water of the BWR could reduce radiation buildup. This hypothesis was developed from correlations of plant data, and subsequently, from laboratory experiments which demonstrated clearly that ionic zinc inhibits the corrosion of stainless steel. The benefits of zinc addition have been measured at the Vallecitos Nuclear Center under and EPRI/GE project. Experimentation and analyses have been performed to evaluate the impact of intentional zinc addition on the IGSCC characteristics of primary system materials and on the performance of the nuclear fuel. It has been concluded that no negative effects are expected. The author conclude that the intentional addition of ionic zinc to the BWR reactor water at a concentration of approximately 10 ppb will provide major benefits in controlling the Co-60 buildup on primary system stainless steel surfaces. The intentional addition of zinc is now a qualified technique for use in BWRs

  16. Key Developments in Ionic Liquid Crystals

    Science.gov (United States)

    Alvarez Fernandez, Alexandra; Kouwer, Paul H. J.

    2016-01-01

    Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material? PMID:27196890

  17. Supported ionic liquid-phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Wasserscheid, P.;

    2005-01-01

    The concept of supported ionic liquid-phase (SILP) catalysis has been demonstrated for gas- and liquid-phase continuous fixed-bed reactions using rhodium phosphine catalyzed hydroformylation of propene and 1-octene as examples. The nature of the support had important influence on both the catalyt...... performance, i.e. activity and selectivity, as well as stability of the SILP catalysts. Noticeably, a high catalyst ligand content together with presence of ionic liquid solvent are prerequisites for obtaining selective rhodium phosphine SILP catalysts systems.......The concept of supported ionic liquid-phase (SILP) catalysis has been demonstrated for gas- and liquid-phase continuous fixed-bed reactions using rhodium phosphine catalyzed hydroformylation of propene and 1-octene as examples. The nature of the support had important influence on both the catalytic...

  18. Enzyme activity in dialkyl phosphate ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, M.F.; Dunn, J.; Li, L.-L.; Handley-Pendleton, J. M.; van der lelie, D.; Wishart, J. F.

    2011-12-01

    The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariellavolvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v.

  19. In-reactor testing of ionic thermometers

    International Nuclear Information System (INIS)

    Ionic thermometers have been tested in a nuclear reactor with attention to the steepness of the ionic conductivity jump and the influence of a glass container on the accuracy of the temperature measurements. It was found that, at the neutron fluxes up to 1.5 x 1018 m-2 s-1 (thermal) and 3 x 1018 m-2 s-1 (fast) in a light water reactor, the change of conductivity jump slope is negligible or nil for an ionic thermometer filled by HgI2, i.e., at 256.0 +- 0.2 0C. The need to use boron-free glass was confirmed. The impact on the accuracy of the temperature point indication in a nuclear reactor core is discussed, as well as obvious inertness of the melting process mechanism to the intense irradiation field

  20. Desulfurization of oxidized diesel using ionic liquids

    Science.gov (United States)

    Wilfred, Cecilia D.; Salleh, M. Zulhaziman M.; Mutalib, M. I. Abdul

    2014-10-01

    The extraction of oxidized sulfur compounds from diesel were carried out using ten types of ionic liquids consisting of different cation and anion i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazoium thiocyanate, 1-butyl-3-methylimidazoium dicyanamide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazoliumhexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, trioctylmethylammonium chloride, 1-propionitrile-3-butylimidazolium thiocyanate, 1-propionitrile-3-butylimidazolium dicyanamide and 1-butyl-6-methylquinolinium dicyanamide. The oxidation of diesel was successfully done using phosphotungstic acid as the catalyst, hydrogen peroxide (H2O2) as the oxidant and trioctylmethylammonium chloride as the phase transfer agent. The oxidation of diesel changes the sulfur compounds into sulfone which increases its polarity and enhances the ionic liquid's extraction performance. Result showed that ionic liquid [C4mquin][N(CN)2] performed the highest sulfur removal (91% at 1:5 diesel:IL ratio) compared to the others.

  1. Ionic profiles close to dielectric discontinuities: Specific ion-surface interactions

    CERN Document Server

    Markovich, Tomer; Orland, Henri

    2016-01-01

    We study, by incorporating short-range ion-surface interactions, ionic profiles of electrolyte solutions close to a non-charged interface between two dielectric media. In order to account for important correlation effects close to the interface, the ionic profiles are calculated beyond mean-field theory, using the loop expansion of the free energy. We show how it is possible to overcome the well-known deficiency of the regular loop expansion close to the dielectric jump, and treat the non-linear boundary conditions within the framework of field theory. The ionic profiles are obtained analytically to one-loop order in the free energy, and their dependence on different ion-surface interactions is investigated. The Gibbs adsorption isotherm, as well as the ionic profiles are used to calculate the surface tension, in agreement with the reverse Hofmeister series. Consequently, from the experimentally-measured surface tension, one can extract a single adhesivity parameter, which can be used within our model to quan...

  2. Ab Initio Investigation of Cation Proton Affinity and Proton Transfer Energy for Energetic Ionic Liquids.

    Science.gov (United States)

    Carlin, Caleb M; Gordon, Mark S

    2016-08-01

    Protonation of the anion in an ionic liquid plays a key role in the hypergolic reaction between ionic liquids and oxidizers such as white fuming nitric acid. To investigate the influence of the cation on the protonation reaction, the deprotonation energy of a set of cations has been calculated at the MP2 level of theory. Specifically, guanidinium, dimethyltriazanium, triethylamine, N-ethyl-N-methyl-pyrrolidinium, N-ethyl-pyridinium, 1,4-dimethyl-1,2,4-triazolium, 1-ethyl-4-methyl-1,2,4-triazolium, and 1-butyl-4-methyl-1,2,4-triazolium were studied. In addition, the net proton transfer energies from the cations to a set of previously studied anions was calculated, demonstrating an inverse correlation between the net proton transfer energy and the likelihood that the cation/anion combination will react hypergolically with white fuming nitric acid. It is suggested that this correlation occurs due to a balance between the energy released by the proton transfer and the rate of proton transfer as determined by the ionicity of the ionic liquid. PMID:27397644

  3. Ionic solutes impact collagen scaffold bioactivity.

    Science.gov (United States)

    Pawelec, K M; Husmann, A; Wardale, R J; Best, S M; Cameron, R E

    2015-02-01

    The structure of ice-templated collagen scaffolds is sensitive to many factors. By adding 0.5 wt% of sodium chloride or sucrose to collagen slurries, scaffold structure could be tuned through changes in ice growth kinetics and interactions of the solute and collagen. With ionic solutes (sodium chloride) the entanglements of the collagen molecule decreased, leading to fibrous scaffolds with increased pore size and decreased attachment of chondrocytes. With non-ionic solutes (sucrose) ice growth was slowed, leading to significantly reduced pore size and up-regulated cell attachment. This highlights the large changes in structure and biological function stimulated by solutes in ice-templating systems. PMID:25649518

  4. Supported ionic liquid-phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Wasserscheid, P.; van Hal, R.

    The concept of supported ionic liquid-phase (SILP) catalysis has been demonstrated for gas- and liquid-phase continuous fixed-bed reactions using rhodium phosphine catalyzed hydroformylation of propene and 1-octene as examples. The nature of the support had important influence on both the catalytic...... performance, i.e. activity and selectivity, as well as stability of the SILP catalysts. Noticeably, a high catalyst ligand content together with presence of ionic liquid solvent are prerequisites for obtaining selective rhodium phosphine SILP catalysts systems....

  5. Inadvertent intrathecal use of ionic contrast agent

    Energy Technology Data Exchange (ETDEWEB)

    Leede, H. van der; Jorens, P.G. [Department of Intensive Care Medicine, University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem (Belgium); Parizel, P. [Department of Radiology, University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem (Belgium); Cras, P. [Department of Neurology, University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem (Belgium)

    2002-07-01

    Intrathecal administration of ionic contrast media may cause severe and fatal neurotoxic reactions due to their hyperosmolarity and ionic nature. They are therefore strictly contraindicated for all radiologic applications involving the central nervous system (e.g., myelography). We present a case in which ioxitalamate was accidentally injected intrathecally. The patient recovered completely due to a combination of the different therapeutic options reported in the literature, including early mechanical ventilation and neuromuscular paralysis, aggressive control of seizures, elevation of head and trunk to prevent cephalad migration of contrast, steroids, cerebrospinal fluid drainage and lavage and prophylactic antibiotics. (orig.)

  6. Viscometric studies of interactions between ionic liquid 1-octyl-3-methyl-imidazolium bromide and polyvinyl pyrrolidone in aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: • Viscosities of PVP in aqueous solution of IL are measured. • The flow activation energies are calculated. • The flow activation energies are correlated in terms of polymer concentration. • Intrinsic viscosity of PVP is decreased by increasing temperature. - Abstract: Ionic liquids are investigated as solvents for polymerization processes, as plasticizers of various kinds of polymers and as components of the polymeric matrixes. In this research, viscosity of polyvinyl pyrrolidone in aqueous solution of ionic liquid, 1-octyl-3-methyl imidazolium bromide are measured at various temperatures. The flow activation energies are calculated and correlated in terms of polymer concentration. From sign of the initial slope of the activation energy versus polymer concentration at zero concentration, it is concluded that thermodynamic quality of ionic liquid aqueous solutions are reduced by increasing temperature. The value of the intrinsic viscosity of polyvinyl pyrrolidone was determined using Huggins equation and thermodynamic parameters of this polymer were calculated on the basis of intrinsic viscosity. Also the effect of ionic liquid, 1-octyl-3-methyl imidazolium bromide on the thermodynamic parameters of dilute aqueous polyvinyl pyrrolidone solutions, such as (polymer + solvent) interaction parameter, theta temperature, the heat of dilution parameter and the entropy of dilution parameter was investigated. Results suggest that the thermodynamic quality of water was increased slightly by the addition of ionic liquid in aqueous solution of polyvinyl pyrrolidone

  7. Applications of ionic liquids in polymer science and technology

    CERN Document Server

    2015-01-01

    This book summarizes the latest knowledge in the science and technology of ionic liquids and polymers in different areas. Ionic liquids (IL) are actively being investigated in polymer science and technology for a number of different applications. In the first part of the book the authors present the particular properties of ionic liquids as speciality solvents. The state-of-the art in the use of ionic liquids in polymer synthesis and modification reactions including polymer recycling is outlined. The second part focuses on the use of ionic liquids as speciality additives such as plasticizers or antistatic agents.  The third part examines the use of ionic liquids in the design of functional polymers (usually called polymeric ionic liquids (PIL) or poly(ionic liquids)). Many important applications in diverse scientific and industrial areas rely on these polymers, like polymer electrolytes in electrochemical devices, building blocks in materials science, nanocomposites, gas membranes, innovative anion sensitive...

  8. Preparation and evaluation of cellulose-dissolving magnetic ionic liquid

    OpenAIRE

    MURAOKA, Jin; Kamiya, Noriho; Ito, Yuji; ムラオカ, ジン; カミヤ, ノリホ; イトウ, ユウジ; 村岡, 仁; 神谷, 典穂; 伊東, 祐二

    2013-01-01

    Ionic liquids have attracted attention as potential pretreatment agents in cellulosic biomass processing. Here we report on a new magnetic ionic liquid that can dissolve crystalline cellulose and be collected by a magnet.

  9. Application of Ionic Liquids in Amperometric Gas Sensors.

    Science.gov (United States)

    Gębicki, Jacek; Kloskowski, Adam; Chrzanowski, Wojciech; Stepnowski, Piotr; Namiesnik, Jacek

    2016-01-01

    This article presents an analysis of available literature data on metrological parameters of the amperometric gas sensors containing ionic liquids as an electrolyte. Four mechanism types of signal generation in amperometric sensors with ionic liquid are described. Moreover, this article describes the influence of selected physico-chemical properties of the ionic liquids on the metrological parameters of these sensors. Some metrological parameters are also compared for amperometric sensors with GDE and SPE electrodes and with ionic liquids for selected analytes. PMID:25830724

  10. Synthesis, characterization and thermal properties of thiosalicylate ionic liquids

    Indian Academy of Sciences (India)

    Cecilia Devi Wilfred; Fadwa Babiker Mustafa

    2013-11-01

    In an attempt to produce new functionalized ionic liquids, a series of thiosalicylate ionic liquids based on imidazolium, ammonium, phosphonium, choline and pyrrolidinium cations were synthesized. The compounds were characterized by Infra Red (IR), Nuclear Magnetic Resonance (NMR) and mass spectra (ESI-MS). Their glass-transition temperatures, melting points and decomposition temperatures have been measured. Physicochemical properties of ionic liquids are influenced by alkyl chain length and nature of the cation of ionic liquids.

  11. Synthetic Organic Electrochemistry in Ionic Liquids: The Viscosity Question

    Directory of Open Access Journals (Sweden)

    Scott T. Handy

    2011-07-01

    Full Text Available Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved.

  12. Current understanding of multi-species biofilms

    OpenAIRE

    Yang, Liang; Liu, Yang; Wu,Hong; Høiby, Niels; Molin, Søren; Zhi-jun SONG

    2011-01-01

    Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually formed by multiple bacterial species. Conventional methods for bacterial cleaning, such as applications of antibiotics and/or disinfectants are often ineffective for biofilm populations due to their...

  13. Ionic liquid containing hydroxamate and N-alkyl sulfamate ions

    Energy Technology Data Exchange (ETDEWEB)

    Friesen, Cody A.; Wolfe, Derek; Johnson, Paul Bryan

    2016-03-15

    Embodiments of the invention are related to ionic liquids and more specifically to ionic liquids used in electrochemical metal-air cells in which the ionic liquid includes a cation and an anion selected from hydroxamate and/or N-alkyl sulfamate anions.

  14. A computer program for geochemical analysis of acid-rain and other low-ionic-strength, acidic waters

    Science.gov (United States)

    Johnsson, P.A.; Lord, D.G.

    1987-01-01

    ARCHEM, a computer program written in FORTRAN 77, is designed primarily for use in the routine geochemical interpretation of low-ionic-strength, acidic waters. On the basis of chemical analyses of the water, and either laboratory or field determinations of pH, temperature, and dissolved oxygen, the program calculates the equilibrium distribution of major inorganic aqueous species and of inorganic aluminum complexes. The concentration of the organic anion is estimated from the dissolved organic concentration. Ionic ferrous iron is calculated from the dissolved oxygen concentration. Ionic balances and comparisons of computed with measured specific conductances are performed as checks on the analytical accuracy of chemical analyses. ARCHEM may be tailored easily to fit different sampling protocols, and may be run on multiple sample analyses. (Author 's abstract)

  15. Understanding the effect of side groups in ionic liquids on carbon-capture properties: a combined experimental and theoretical effort

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Fangyong [Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engingeering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Lartey, Michael [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Damodaran, Krishnan [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Univ. of Pittsburgh, PA (United States). Dept. of Chemistry; Albenze, Erik [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); URS Corporation, South Park, PA (United States); Thompson, Robert L. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); URS Corporation, South Park, PA (United States); Kim, Jihan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Science Div.; Harancyzk, Maciel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Div.; Nulwala, Hunaid B. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carnegie Mellon Univ., Pittsburgh, PA (United States); Luebke, David R. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Smit, Berend [Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engingeering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

    2013-01-01

    Ionic liquids are an emerging class of materials with applications in a variety of fields. Steady progress has been made in the creation of ionic liquids tailored to specific applications. However, the understanding of the underlying structure–property relationships has been slower to develop. As a step in the effort to alleviate this deficiency, the influence of side groups on ionic liquid properties has been studied through an integrated approach utilizing synthesis, experimental determination of properties, and simulation techniques. To achieve this goal, a classical force field in the framework of OPLS/Amber force fields has been developed to predict ionic liquid properties accurately. Cu(I)-catalyzed click chemistry was employed to synthesize triazolium-based ionic liquids with diverse side groups. Values of densities were predicted within 3% of experimental values, whereas self-diffusion coefficients were underestimated by about an order of magnitude though the trends were in excellent agreement, the activation energy calculated in simulation correlates well with experimental values. The predicted Henry coefficient for CO{sub 2} solubility reproduced the experimentally observed trends. This study highlights the importance of integrating experimental and computational approaches in property prediction and materials development, which is not only useful in the development of ionic liquids for CO{sub 2} capture but has application in many technological fields.

  16. Thermal and structural properties of ionic fluids.

    Science.gov (United States)

    Bartsch, Hendrik; Dannenmann, Oliver; Bier, Markus

    2015-04-01

    The electrostatic interaction in ionic fluids is well known to give rise to a characteristic phase behavior and structure. Sometimes its long range is proposed to single out the electrostatic potential over other interactions with shorter ranges. Here the importance of the range for the phase behavior and the structure of ionic fluids is investigated by means of grandcanonical Monte Carlo simulations of the lattice restricted primitive model (LRPM). The long-ranged electrostatic interaction is compared to various types of short-ranged potentials obtained by sharp and/or smooth cutoff schemes. Sharply cutoff electrostatic potentials are found to lead to a strong dependence of the phase behavior and the structure on the cutoff radius. However, when combined with a suitable additional smooth cutoff, the short-ranged LRPM is found to exhibit quantitatively the same phase behavior and structure as the conventional long-ranged LRPM. Moreover, the Stillinger-Lovett perfect screening property, which is well known to be generated by the long-ranged electrostatic potential, is also fulfilled by short-ranged LRPMs with smooth cutoffs. By showing that the characteristic phase behavior and structure of ionic fluids can also be found in systems with short-ranged potentials, one can conclude that the decisive property of the electrostatic potential in ionic fluids is not the long range but rather the valency dependence. PMID:25974477

  17. Introduction on Special Issue: Ionic Liquids

    Czech Academy of Sciences Publication Activity Database

    Jacquemin, J.; Bendová, Magdalena

    2015-01-01

    Roč. 44, 3-4 (2015), s. 379-381. ISSN 0095-9782 Institutional support: RVO:67985858 Keywords : ionic liquids * E. Hála * special issue Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.177, year: 2014

  18. Solvation and Reaction in Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Maroncelli, Mark

    2015-01-15

    The long-range goal of our DOE-sponsored research is to obtain a fundamental understanding of solvation effects on photo-induced charge transfer and related processes. Much of the focus during the past funding period has been on studies of ionic liquids and on characterizing various reactions with which to probe the nature of this interesting new solvent medium.

  19. Ionic liquids - media for polyaniline preparation

    Czech Academy of Sciences Publication Activity Database

    Konyushenko, Elena; Stejskal, Jaroslav; Morávková, Zuzana; Trchová, Miroslava; Prokeš, J.

    Atlanta : Center for Organic Photonics and Electronics - Georgia Institute of Technology, 2012. s. 280. [International Conference on Science and Technology of Synthetic Metals 2012 - ICSM 2012. 08.07.2012-13.07.2012, Atlanta] Institutional support: RVO:61389013 Keywords : polyaniline * ionic liquids Subject RIV: CD - Macromolecular Chemistry

  20. Carbon dioxide in ionic liquid microemulsions.

    Science.gov (United States)

    Zhang, Jianling; Han, Buxing; Li, Jianshen; Zhao, Yueju; Yang, Guanying

    2011-10-10

    Tailor-made emulsion: a CO(2) -in-ionic-liquid microemulsion was produced for the first time. The CO(2)-swollen micelles are "tunable" because the micellar size can be easily adjusted by changing the pressure of CO(2). The microemulsion has potential applications in materials synthesis, chemical reactions, and extraction. PMID:21898733

  1. Reactions of Starch in Ionic Liquids

    Science.gov (United States)

    We found that starches are found to be soluble at 80 ºC in ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-butyl-3-methylimidazolium dicyanamide (BMIMdca) in concentration up to 10% (w/w). Higher concentrations of biopolymers in these novel solvents resulted in solutions w...

  2. Esterification of Starch in Ionic Liquids

    Science.gov (United States)

    We shall discuss the use of various ionic liquids in the preparation of starch esters. Starch was reacted with vinyl acetate in different 1-butyl-3-methylimidazolium (bmim) salts as solvents in an effort to produce starches with different acetylation patterns. Overall degree of substitution (DS) w...

  3. Neuroendocrine control of ionic balance in zebrafish.

    Science.gov (United States)

    Kwong, Raymond W M; Kumai, Yusuke; Perry, Steve F

    2016-08-01

    Zebrafish (Danio rerio) is an emerging model for integrative physiological research. In this mini-review, we discuss recent advances in the neuroendocrine control of ionic balance in this species, and identify current knowledge gaps and issues that would benefit from further investigation. Zebrafish inhabit a hypo-ionic environment and therefore are challenged by a continual loss of ions to the water. To maintain ionic homeostasis, they must actively take up ions from the water and reduce passive ion loss. The adult gill or the skin of larvae are the primary sites of ionic regulation. Current models for the uptake of major ions in zebrafish incorporate at least three types of ion transporting cells (also called ionocytes); H(+)-ATPase-rich cells for Na(+) uptake, Na(+)/K(+)-ATPase-rich cells for Ca(2+) uptake, and Na(+)/Cl(-)-cotransporter expressing cells for both Na(+) and Cl(-) uptake. The precise molecular mechanisms regulating the paracellular loss of ions remain largely unknown. However, epithelial tight junction proteins, including claudins, are thought to play a critical role in reducing ion losses to the surrounding water. Using the zebrafish model, several key neuroendocrine factors were identified as regulators of epithelial ion movement, including the catecholamines (adrenaline and noradrenaline), cortisol, the renin-angiotensin system, parathyroid hormone and prolactin. Increasing evidence also suggests that gasotransmitters, such as H2S, are involved in regulating ion uptake. PMID:27179885

  4. VOC and HAP recovery using ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Michael R. Milota : Kaichang Li

    2007-05-29

    During the manufacture of wood composites, paper, and to a lesser extent, lumber, large amounts of volatile organic compounds (VOCs) such as terpenes, formaldehyde, and methanol are emitted to air. Some of these compounds are hazardous air pollutants (HAPs). The air pollutants produced in the forest products industry are difficult to manage because the concentrations are very low. Presently, regenerative thermal oxidizers (RTOs and RCOs) are commonly used for the destruction of VOCs and HAPs. RTOs consume large amounts of natural gas to heat air and moisture. The combustion of natural gas generates increased CO2 and NOx, which have negative implications for global warming and air quality. The aforementioned problems are addressed by an absorption system containing a room-temperature ionic liquid (RTIL) as an absorbent. RTILs are salts, but are in liquid states at room temperature. RTILs, an emerging technology, are receiving much attention as replacements for organic solvents in industrial processes with significant cost and environmental benefits. Some of these processes include organic synthesis, extraction, and metal deposition. RTILs would be excellent absorbents for exhausts from wood products facilities because of their unique properties: no measurable vapor pressure, high solubility of wide range of organic compounds, thermal stability to 200°C (almost 400°F), and immisciblity with water. Room temperature ionic liquids were tested as possible absorbents. Four were imidizolium-based and were eight phosphonium-based. The imidizolium-based ionic liquids proved to be unstable at the conditions tested and in the presence of water. The phosphonium-based ionic liquids were stable. Most were good absorbents; however, cleaning the contaminates from the ionic liquids was problematic. This was overcome with a higher temperature (120°C) than originally proposed and a very low pressure (1 kPa. Absorption trials were conducted with tetradecy

  5. Ionic association and interactions in aqueous methylsulfate alkyl-imidazolium-based ionic liquids

    International Nuclear Information System (INIS)

    Highlights: • Viscosity and electrical conductivity were determined in aqueous ionic liquids. • For the shorter IL the viscosity was lower and the electrical conductivity higher. • NMR and IR were used to study ionic association and interactions in aqueous ILs. • The main change in the ionic association was only observed for high water contents. • In IR, the SO3 asymmetric stretching band is a probe of structural changes. - Abstract: Several experimental techniques were used to study ionic association and interactions in aqueous [C1C2Im][MeSO4], 1-ethyl-3-methylimidazolium methylsulfate, and [C1C4Im][MeSO4], 1-butyl-3-methylimidazolium methylsulfate. Two transport properties, viscosity and electrical conductivity, were determined for these two binary mixtures. For a better assessment of the ionic association and the perturbation of water into the molecular structure of the ionic liquid, diffusion coefficients of ions and water molecules were obtained by NMR spectroscopy while molecular interactions were probed by IR spectroscopy. The comparison of the two ionic liquids shows that for the shorter alkyl chain the viscosity was lower and the electrical conductivity was higher. While the viscosity of the mixture drops already with small additions of water, the electrical conductivity of the solution is only significantly increased for high water concentrations. A maximum is observed for compositions around xwater = (0.90 to 0.95). The SO3 asymmetric stretching band of the IR spectrum can be used as a probe to observe the evolution of the structure around the anion which was mainly occurring for high concentrations of water. Several experimental techniques show than the main change in the ionic association was only observed for high water contents (water mole fraction > 0.8)

  6. Syntheses and applications of ionic liquids as solvents and reactants : natural substances dissolution, esterification ionic tagging

    OpenAIRE

    Zhao, Bin

    2012-01-01

    The present thesis deals with the applications of ionic liquids (ILs), especially carboxylate-based ILs. The first part describes the syntheses and uses of ILs as solvents for natural compounds to dissolve cellulose and to extract betulin. The second part reveals their applications as reactants for esterification and ionic tagging. Dissolution of cellulose allows easier processing of this important biogenic feedstock. For this, ILs have been proposed. To foster understanding of the structure ...

  7. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    OpenAIRE

    EeroSalminen; Jyri-PekkaTuomoMikkola

    2014-01-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths ...

  8. Modeling of ionic transport in solid polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Cheang, P L; Teo, L L; Lim, T L, E-mail: plcheang@mmu.edu.my [Centre for Foundation Studies and Extension Education, Multimedia University, Jln Ayer Keroh Lama, 75450 Melaka (Malaysia)

    2010-05-15

    A Monte Carlo model describing the ionic trans port in solid polyme relectrolyte is developed. Single cation simulation is carried out using hopping rate to study the transport mechanism of a thermally activated ion in solid polymer electrolyte. In our model, the ion is able to hop along a polymer chain and to jump between different chains, surmounting energy barriers that consist of polymer's activation energy and the externally applied electric field. The model is able to trace the motion of ion across polymer electrolyte. The mean hopping distance is calculated based on the available open bond in the next nearest side. Random numbers are used to determine the hopping distances, free flight times, final energy and direction of the cation after successful hop. Drift velocity and energy of cation are simulated in our work. The model is expected to be able to simulate the lithium-polymer battery in future.

  9. Viscosity mixing rules for binary systems containing one ionic liquid.

    Science.gov (United States)

    Tariq, Mohammed; Altamash, Tausif; Salavera, Daniel; Coronas, Alberto; Rebelo, Luis P N; Canongia Lopes, Jose N

    2013-06-24

    In this work the applicability of four of the most commonly used viscosity mixing rules to [ionic liquid (IL)+molecular solvent (MS)] systems is assessed. More than one hundred (IL+MS) binary mixtures were selected from the literature to test the viscosity mixing rules proposed by 1) Hind (Hi), 2) Grunberg and Nissan (G-N), 3) Herric (He) and 4) Katti and Chaudhri (K-C). The analyses were performed by estimating the average (absolute or relative) deviations, AADs and ARDs, between the available experimental data and the predicted ideal mixture viscosity values obtained by means of each rule. The interaction terms corresponding to the adjustable parameters inherent to each rule were also calculated and their trends discussed. PMID:23650138

  10. Quantum Decoherence Timescales for Ionic Superposition States in Ion Channels

    CERN Document Server

    Salari, V; Fazileh, F; Shahbazi, F

    2014-01-01

    There are many controversial and challenging discussions about quantum effects in microscopic structures in neurons of the human brain. The challenge is mainly because of quick decoherence of quantum states due to hot, wet and noisy environment of the brain which forbids long life coherence for brain processing. Despite these critical discussions, there are only a few number of published papers about numerical aspects of decoherence in neurons. Perhaps the most important issue is offered by Max Tegmark who has calculated decoherence times for the systems of "ions" and "microtubules" in neurons of the brain. In fact, Tegmark did not consider ion channels which are responsible for ions displacement through the membrane and are the building blocks of electrical membrane signals in the nervous system. Here, we would like to re-investigate decoherence times for ionic superposition states by using the data obtained via molecular dynamics simulations. Our main approach is according to what Tegmark has used before. I...

  11. Modeling of ionic transport in solid polymer electrolytes

    International Nuclear Information System (INIS)

    A Monte Carlo model describing the ionic trans port in solid polyme relectrolyte is developed. Single cation simulation is carried out using hopping rate to study the transport mechanism of a thermally activated ion in solid polymer electrolyte. In our model, the ion is able to hop along a polymer chain and to jump between different chains, surmounting energy barriers that consist of polymer's activation energy and the externally applied electric field. The model is able to trace the motion of ion across polymer electrolyte. The mean hopping distance is calculated based on the available open bond in the next nearest side. Random numbers are used to determine the hopping distances, free flight times, final energy and direction of the cation after successful hop. Drift velocity and energy of cation are simulated in our work. The model is expected to be able to simulate the lithium-polymer battery in future.

  12. Evaluation of ionic liquids as absorbents for ammonia absorption refrigeration cycles using COSMO-based process simulations

    International Nuclear Information System (INIS)

    Highlights: • NH3–IL absorption cycles are modeled by COSMO-based Aspen simulations. • Proposed a priori computational approach is validated using experimental data. • Cycle performance was analyzed for conventional and task-specific ILs. • IL solvents with high NH3 absorption capacity improve the cycle performance. • Using IL mixtures is revealed as promising alternative in NH3 absorption applications. - Abstract: COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia + ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant + absorbent) solutions. This behavior is strongly modulated by the ammonia absorption

  13. Ionic conductivity and molecular dynamic behavior in supramolecular ionic networks; the effect of lithium salt addition

    International Nuclear Information System (INIS)

    Highlights: • Novel amorphous and semicrystalline supramolecular ionic networks, iNets, have been synthesised by self-assembly of dicationic and dianionic molecules. • Significant enhancement of conductivity of the semicrystalline iNets has been achieved upon doping with LiTFSI. • Solid state NMR of the semicrystalline iNets shows narrower lines upon doping due to increased mobility in the network. - Abstract: Supramolecular ionic networks combine singular properties such as self-healing behaviour and ionic conductivity. In this work we present an insight into the ionic conductivity and molecular dynamic behaviour of an amorphous and semicrystalline supramolecular ionic networks (iNets) that were synthesised by self-assembly of difunctional imidazolium dicationic molecules coupled with (trifluoromethane-sulfonyl) imide dianionic molecules. Relatively low ionic conductivity values were obtained for the semicrystalline iNet below its melting point (Tm = 101 °C) in comparison with the amorphous iNet for which the conductivity significantly increased (∼3 orders of magnitude) above 100 °C. Upon LiTFSI doping, the semicrystalline iNet reached conductivity values ∼ 10−3 S cm−1 due to enhanced mobility of the network which was supported by solid-state static NMR. Furthermore, the overlapping of 19F and 7Li resonance lines from both the semicrystalline network and the LiTFSI suggests fast molecular motions

  14. Effect of Electric Field Alignment on Morphology and Ionic Conductivity of Polymerized Ionic Liquid Block Copolymers

    Science.gov (United States)

    Sharick, Sharon; Nykaza, Jacob; Elabd, Yossef A.; Winey, Karen I.

    2014-03-01

    Polymerized ionic liquid (PIL) block copolymers are appealing for numerous electrochemical applications, including solid polymer electrolyte membranes for batteries and anion exchange membranes for fuel cells. The extent to which the reduced segmental motion caused by the non-conducting polymer segments and grain boundaries between block copolymer microdomains are detrimental to ionic conductivity is unknown. Increased long-range morphological order and connectivity of PIL microdomains are key to understanding the ion transport mechanism and may improve the ionic conductivity of PIL block copolymers. The effect of electric field on the morphology and ionic conductivity of poly(styrene- b-1-[2-(methacryloyloxy)ethyl]-3-butylimidazolium-bis(trifluoromethanesulfonyl)imide)) (PS- b-PMEBIm-TFSI) will be discussed as a function of microdomain orientation. Electric field is used to increase the perpendicular orientation of ion-conducting pathways with respect to the electrodes. The morphology and ionic conductivity were characterized by small-angle X-ray scattering and electrochemical impedance spectroscopy, respectively. The ionic conductivity of unoriented and oriented block copolymers will be compared to the PIL homopolymer, PMEBIm-TFSI, using the Sax and Ottino model.

  15. Application of Multi-Species Microbial Bioassay to Assess the Effects of Engineered Nanoparticles in the Aquatic Environment: Potential of a Luminous Microbial Array for Toxicity Risk Assessment (LumiMARA on Testing for Surface-Coated Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    YounJung Jung

    2015-07-01

    Full Text Available Four different manufactured surface-coated silver nanoparticles (AgNPs with coating of citrate, tannic acid, polyethylene glycol, and branched polyethylenimine were used in this study. The toxicity of surface-coated AgNPs was evaluated by a luminous microbial array for toxicity risk assessment (LumiMARA using multi-species of luminescent bacteria. The salt stability of four different AgNPs was measured by UV absorbance at 400 nm wavelength, and different surface-charged AgNPs in combination with bacteria were observed using scanning electron microscopy (SEM. Both branched polyethylenimine (BPEI-AgNPs and polyethylene glycol (PEG-AgNPs were shown to be stable with 2% NaCl (non-aggregation, whereas both citrate (Cit-AgNPs and tannic acid (Tan-AgNPs rapidly aggregated in 2% NaCl solution. The values of the 50% effective concentration (EC50 for BPEI-AgNPs in marine bacteria strains (1.57 to 5.19 mg/L were lower than those for the other surface-coated AgNPs (i.e., Cit-AgNPs, Tan-AgNPs, and PEG-AgNPs. It appears that the toxicity of AgNPs could be activated by the interaction of positively charged AgNPs with the negatively charged bacterial cell wall from the results of LumiMARA. LumiMARA for toxicity screening has advantageous compared to a single-species bioassay and is applicable for environmental samples as displaying ranges of assessment results.

  16. DNA denaturation in ionic solution

    Science.gov (United States)

    Maity, Arghya; Singh, Amar; Singh, Navin

    2016-05-01

    Salt or cations, present in solution play an important role in DNA denaturation and folding kinetics of DNA helix. In this work we study the thermal melting of double stranded DNA (dsDNA) molecule using Peyrard Bishop Dauxois (PBD) model. We modify the potential of H-bonding between the bases of the complimentary strands to introduce the salt and solvent effect. We choose different DNA sequences having different contents of GC pairs and calculate the melting temperatures. The melting temperature increases logarithmically with the salt concentration of the solution. The more GC base pairs in the chain enhance the stability of DNA chain at a fix salt concentration. The obtained results are in good accordance with experimental findings.

  17. Polarized mixtures with ionic tracers

    Energy Technology Data Exchange (ETDEWEB)

    Magnarelli, Lorenzo [Dipartimento di Ingegneria Meccanica e Strutturale, Universita di Trento, Via Mesiano 77, 38050 Povo, Trento (Italy)], E-mail: lorenzo.magnarelli@ing.unitn.it

    2009-08-14

    A model of a polarized mixture is developed and the effects of migration of ions are also accounted for. The rate of the polarization power in some way furnishes power to the mixture. The electrical external power is calculated and by means of a requirement of invariance of the power, the standard balance laws are deduced. The ions dissolved in the mixture and subject to the electric field are considered like tracers and their migration is discussed. We show that their migration is ruled by the Nernst-Planck equation. In the final section, we adapt the description of the model to the setting of complex bodies and the microstructural evolution equations are derived.

  18. Polarized mixtures with ionic tracers

    International Nuclear Information System (INIS)

    A model of a polarized mixture is developed and the effects of migration of ions are also accounted for. The rate of the polarization power in some way furnishes power to the mixture. The electrical external power is calculated and by means of a requirement of invariance of the power, the standard balance laws are deduced. The ions dissolved in the mixture and subject to the electric field are considered like tracers and their migration is discussed. We show that their migration is ruled by the Nernst-Planck equation. In the final section, we adapt the description of the model to the setting of complex bodies and the microstructural evolution equations are derived.

  19. Multigrid Methods in Electronic Structure Calculations

    CERN Document Server

    Briggs, E L; Bernholc, J

    1996-01-01

    We describe a set of techniques for performing large scale ab initio calculations using multigrid accelerations and a real-space grid as a basis. The multigrid methods provide effective convergence acceleration and preconditioning on all length scales, thereby permitting efficient calculations for ill-conditioned systems with long length scales or high energy cut-offs. We discuss specific implementations of multigrid and real-space algorithms for electronic structure calculations, including an efficient multigrid-accelerated solver for Kohn-Sham equations, compact yet accurate discretization schemes for the Kohn-Sham and Poisson equations, optimized pseudo\\-potentials for real-space calculations, efficacious computation of ionic forces, and a complex-wavefunction implementation for arbitrary sampling of the Brillioun zone. A particular strength of a real-space multigrid approach is its ready adaptability to massively parallel computer architectures, and we present an implementation for the Cray-T3D with essen...

  20. Observation of ionic Coulomb blockade in nanopores.

    Science.gov (United States)

    Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; Di Ventra, Massimiliano; Radenovic, Aleksandra

    2016-08-01

    Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels. PMID:27019385

  1. Phase Behavior of Mixtures of Ionic Liquids and Organic Solvents

    DEFF Research Database (Denmark)

    Abildskov, Jens; Ellegaard, Martin Dela; O’Connell, J.P.

    2010-01-01

    implemented, leading to an entirely predictive method for densities of mixed compressed ionic liquids. Quantitative agreement with experimental data is obtained over wide ranges of conditions. Previously, the method has been applied to solubilities of sparingly soluble gases in ionic liquids and in organic......A corresponding-states form of the generalized van der Waals equation, previously developed for mixtures of an ionic liquid and a supercritical solute, is here extended to mixtures including an ionic liquid and a solvent (water or organic). Group contributions to characteristic parameters are...... solvents. Here we show results for heavier and more-than-sparingly solutes such as carbon dioxide and propane in ionic liquids....

  2. Charged defects in graphene and the ionicity of hexagonal boron nitride in direct images

    OpenAIRE

    Meyer, Jannik C.; Kurasch, Simon; Park, Hye Jin; Skakalova, Viera; Künzel, Daniela; Groß, Axel; Chuvilin, Andrey; Algara-Siller, Gerardo; Roth, Siegmar; Iwasaki, Takayuki; Starke, Ulrich; Smet, Jürgen; Kaiser, Ute

    2010-01-01

    We report on the detection and charge distribution analysis for nitrogen substitutional dopants in single layer graphene membranes by aberration-corrected high-resolution transmission electron microscopy (HRTEM). Further, we show that the ionicity of single-layer hexagonal boron nitride can be confirmed from direct images. For the first time, we demonstrate by a combination of HRTEM experiments and first-principles electronic structure calculations that adjustments to the atomic potentials du...

  3. Studies on the concentration and mination of radiocobalt in organic complexed and ionic forms by mussel, Mytilisepta virgatus

    International Nuclear Information System (INIS)

    Paper electrophoretic behavior of cobalt in sea water media with or without glycine was investigated under laboratory conditions. No detectable change in the apparent electrophoretic mobility of synthesized trisglycinato cobalt (III) complex in a simple sea water medium was observed during the ageing period of 41 days under cintinuous aeration at 15 +- 20C. Cobaltous ion in a sea water medium without glycine was hydrolyzed and diffuse electrophoretic zone was observed with ageing. The uptake and elimination of the different chemical forms of radiocobalt by mussel, Mytilisepta virgatus, were studied under laboratory conditions. The synthesized 57Co-trisglycinate and 60Co in cobalt chloride were used as tracers for organic complexed and ionic cobalt, respectively. The rates of uptake, the turnover rates and the concentration factors for organic cobalt in both the soft parts and the shell of mussel were smaller than those for ionic cobalt from the analysis based on the exponential model. In the uptake experiments, the exchanged cobalt in the soft parts of mussel could be calculated to be 0.26% for organic cobalt and 1.93% for ionic cobalt at equilibrium state, respectively. The whole-body retention curves of both radiocobalt consisted of at least the two components. The initial elimination of organic cobalt was larger than that of ionic cobalt. Mass balance calculations at the conclusion of the uptake experiments showed a remarkable difference between the distributions of organic and ionic cobalt in the systems. (J.P.N.)

  4. Hydrogen production from glucose in ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Assenbaum, D.W.; Taccardi, N.; Berger, M.E.M.; Boesmann, A.; Enzenberger, F.; Woelfel, R.; Wasserscheid, P. [Erlangen-Nuernberg Univ. (Germany). Lehrstuhl fuer chemische Reaktionstechnik

    2010-07-01

    technologies suffer from the fact that the overall reaction rates are often restricted by mass and heat transport problems. Lastly, there are severe limitations concerning the feedstock selection as for some important substrates, such as e.g. glucose, the process can only be operated in very diluted systems to avoid rapid tar formation [22,23,24]. In this contribution we describe for the first time a catalytic reaction system producing hydrogen from glucose in astonishingly high selectivities using a single reaction step under very mild conditions. The catalytic reaction system is characterized by its homogeneous nature and comprises a Ru-complex catalyst dissolved and stabilized in an ionic liquid medium. Ionic liquids are salts of melting points below 100 C [25]. These liquid materials have attracted much interest in the last decade as solvents for catalytic reactions [26] and separation technologies (extraction, distillation) [27,28,29,30,31,32]. Besides, these liquids have found industrial applications as process fluids for mechanic [33] and electrochemical applications [34]. Finally, from the pioneering work of Rogers and co-workers, it is known that ionic liquids are able to dissolve significant amounts of water-insoluble biopolymers (such as e.g. cellulose and chitin)[35] and even complex biopolymer mixtures, such as e.g. wood, have been completely dissolved in some ionic liquids [36]. In our specific application, the role of the ionic liquid is threefold: a) the ionic liquid dissolves the carbohydrate starting material thus expanding the range of applicable carbohydrate to water insoluble polymers; b) the ionic liquid provides a medium to dissolve and stabilize the catalyst; c) the ionic liquid dissolves hydrogen at a very low level, so inhibiting any possible collateral hydrogen-consuming process (detailed investigation of the hydrogen solubility in ionic liquids have been reported by e.g. Brennecke and coworkers [37]). (orig.)

  5. Structure, ionic Conductivity and mobile Carrier Density in Fast Ionic Conducting Chalcogenide Glasses

    International Nuclear Information System (INIS)

    This thesis consists of six sections. The first section gives the basic research background on the ionic conduction mechanism in glass, polarization in the glass, and the method of determining the mobile carrier density in glass. The proposed work is also included in this section. The second section is a paper that characterizes the structure of MI + M2S + (0.1 Ga2S3 + 0.9 GeS2) (M = Li, Na, K and Cs) glasses using Raman and IR spectroscopy. Since the ionic radius plays an important role in determining the ionic conductivity in glasses, the glass forming range for the addition of different alkalis into the basic glass forming system 0.1 Ga2S3 + 0.9 GeS2 was studied. The study found that the change of the alkali radius for the same nominal composition causes significant structure change to the glasses. The third section is a paper that investigates the ionic conductivity of MI + M2S + (0.1Ga2S3 + 0.9 GeS2) (M = Li, Na, K and Cs) glasses system. Corresponding to the compositional changes in these fast ionic conducting glasses, the ionic conductivity shows changes due to the induced structural changes. The ionic radius effect on the ionic conductivity in these glasses was investigated. The fourth section is a paper that examines the mobile carrier density based upon the measurements of space charge polarization. For the first time, the charge carrier number density in fast ionic conducting chalcogenide glasses was determined. The experimental impedance data were fitted using equivalent circuits and the obtained parameters were used to determine the mobile carrier density. The influence of mobile carrier density and mobility on the ionic conductivity was separated. The fifth section is a paper that studies the structures of low-alkali-content Na2S + B2S3 (x (le) 0.2) glasses by neutron and synchrotron x-ray diffraction. Similar results were obtained both in neutron and synchrotron x-ray diffraction experiments. The results provide direct structural evidence that doping

  6. Structure, ionic Conductivity and mobile Carrier Density in Fast Ionic Conducting Chalcogenide Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wenlong Yao

    2006-12-12

    This thesis consists of six sections. The first section gives the basic research background on the ionic conduction mechanism in glass, polarization in the glass, and the method of determining the mobile carrier density in glass. The proposed work is also included in this section. The second section is a paper that characterizes the structure of MI + M{sub 2}S + (0.1 Ga{sub 2}S{sub 3} + 0.9 GeS{sub 2}) (M = Li, Na, K and Cs) glasses using Raman and IR spectroscopy. Since the ionic radius plays an important role in determining the ionic conductivity in glasses, the glass forming range for the addition of different alkalis into the basic glass forming system 0.1 Ga{sub 2}S{sub 3} + 0.9 GeS{sub 2} was studied. The study found that the change of the alkali radius for the same nominal composition causes significant structure change to the glasses. The third section is a paper that investigates the ionic conductivity of MI + M{sub 2}S + (0.1Ga{sub 2}S{sub 3} + 0.9 GeS{sub 2}) (M = Li, Na, K and Cs) glasses system. Corresponding to the compositional changes in these fast ionic conducting glasses, the ionic conductivity shows changes due to the induced structural changes. The ionic radius effect on the ionic conductivity in these glasses was investigated. The fourth section is a paper that examines the mobile carrier density based upon the measurements of space charge polarization. For the first time, the charge carrier number density in fast ionic conducting chalcogenide glasses was determined. The experimental impedance data were fitted using equivalent circuits and the obtained parameters were used to determine the mobile carrier density. The influence of mobile carrier density and mobility on the ionic conductivity was separated. The fifth section is a paper that studies the structures of low-alkali-content Na{sub 2}S + B{sub 2}S{sub 3} (x {le} 0.2) glasses by neutron and synchrotron x-ray diffraction. Similar results were obtained both in neutron and synchrotron x

  7. Solid State Ionic Materials - Proceedings of the 4th Asian Conference on Solid State Ionics

    Science.gov (United States)

    Chowdari, B. V. R.; Yahaya, M.; Talib, I. A.; Salleh, M. M.

    1994-07-01

    The Table of Contents for the full book PDF is as follows: * Preface * I. INVITED PAPERS * Diffusion of Cations and Anions in Solid Electrolytes * Silver Ion Conductors in the Crystalline State * NMR Studies of Superionic Conductors * Hall Effect and Thermoelectric Power in High Tc Hg-Ba-Ca-Cu-O Ceramics * Solid Electrolyte Materials Prepared by Sol-Gel Chemistry * Preparation of Proton-Conducting Gel Films and their Application to Electrochromic Devices * Thin Film Fuel Cells * Zirconia based Solid Oxide Ion Conductors in Solid Oxide Fuel Cells * The Influence of Anion Substitution on Some Phosphate-based Ion Conducting Glasses * Lithium Intercalation in Carbon Electrodes and its Relevance in Rocking Chair Batteries * Chemical Sensors using Proton Conducting Ceramics * NMR/NQR Studies of Y-Ba-Cu-O Superconductors * Silver Molybdate Glasses and Battery Systems * New Highly Conducting Polymer Ionics and their Application in Electrochemical Devices * Study of Li Electrokinetics on Oligomeric Electrolytes using Microelectrodes * Calculation of Conductivity for Mixed-Phase Electrolytes PEO-MX-Immiscible Additive by Means of Effective Medium Theory * II. CONTRIBUTED PAPERS * Phase Relationship and Electrical Conductivity of Sr-V-O System with Vanadium Suboxide * Amorphous Li+ Ionic Conductors in Li2SO4-Li2O-P2O5 System * Fast Ion Transport in KCl-Al2O3 Composites * The Effect of the Second Phase Precipitation on the Ionic Conductivity of Zr0.85Mg0.15O1.85 * Conductivity Measurements and Phase Relationships in CaCl2-CaHCl Solid Electrolyte * Relationships Between Crystal Structure and Sodium Ion Conductivity in Na7Fe4(AsO4)6 and Na3Al2(AsO4)3 * Electrical Conductivity and Solubility Limit of Ti4+ Ion in Na1+x TiyZr2-ySixP3-xO12 System * Study on Sodium Fast Ion Conductors of Na1+3xAlxTi2-xSi2xP3-2xO12 System * Influences of Zirconia on the Properties of β''-Alumina Ceramics * Decay of Luminescence from Cr3+ Ions in β-Alumina * Lithium Ion Conductivity in the Li4XO4-Li2

  8. Active chemisorption sites in functionalized ionic liquids for carbon capture.

    Science.gov (United States)

    Cui, Guokai; Wang, Jianji; Zhang, Suojiang

    2016-07-25

    Development of novel technologies for the efficient and reversible capture of CO2 is highly desired. In the last decade, CO2 capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO2 by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO2 using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid-amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO2 absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO2 capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined. PMID:27243042

  9. Periodicity and map for discovery of new ionic liquids

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    There is virtually no limit in the number of ionic liquids. How to select proper ones or discover new ones with desirable properties in such a large pool of ionic liquids? It has become a bottleneck in the researches and applications of ionic liquids. Mendeleev's periodic law states that the properties of the elements vary periodically. Whether the similar regularity exists among ionic or molecular fragments of compounds is an interesting topic. In this work, we attempted to establish a periodicity and draw a "map" of ionic liquids for providing definite guidance to discover, design, and select the proper ionic liquids rather than trial-and-error. If a complete regularity of the system of ionic liquids can be finally established in the future, we are near an epoch in understanding the existing differences and the reasons for the similarity of the ions or molecular fragments.

  10. Complexation of Tc(IV) with EDTA at varying ionic strength of NaCl

    International Nuclear Information System (INIS)

    The stability constant for Tc(IV)/EDTA complexes were determined using a solvent extraction technique at varying ionic strength (NaCl) and the specific ion interaction theory model allowed for calculating stability constants at zero ionic strength. The stability constants at zero ionic strength for the formation of the TcOEDTA2- and TcOHEDTA- complexes are 1020.0±0.4 and 1025.3±0.5, respectively. The modeled Tc(IV) solubility was calculated to be 3.9 x 10-7 M at near-neutral pH and in presence of 2.5 mM EDTA, a result found to be in good agreement with published solubility experimental data. Speciation calculations showed that TcOEDTA2- is the predominant species between pH 4 and 7.5 in presence of 0.171 mM EDTA, while TcO(OH)20 is predominant in basic solution. These studies show that EDTA has a very strong affinity for complexation with Tc(IV) and can increase the environmental mobility of Tc(IV). (orig.)

  11. Structure of the room-temperature ionic liquid 1-hexyl-3-methylimidazolium hydrogen sulfate: conformational isomerism.

    Science.gov (United States)

    Kiefer, Johannes; Pye, Cory C

    2010-06-24

    The acidic room-temperature ionic liquid 1-hexyl-3-methylimidazolium hydrogen sulfate has recently been identified to have beneficial properties for practical applications in catalysis and electrochemistry. In the present work, the conformational isomerism of this ionic liquid is studied by means of density functional theory calculations and experiments in terms of infrared absorption and Raman scattering spectroscopy. For the hydrogen sulfate anion, the trans conformer is found to be the favored isomer in the ionic liquid. For the 1-hexyl-3-methylimidazolium cation, three different low-energy conformations were obtained, differing only in the orientation of the hexyl chain. The comparison of vibrational frequencies with IR and Raman data showed good agreement for all three conformations, indicating their presence in the ionic liquid. Beyond revealing the conformational information, the experimental spectra indicate strong interionic interactions. Vibrations of sulfuric acid could be observed, indicating possible proton transfer from the cation to the anion. This is further supported by the appearance of modes around 2000 cm(-1) in the IR spectrum, which could tentatively be assigned to C2-H stretching vibrations red-shifted as a result of strong interionic hydrogen bonds as a prerequisite of proton transfer. PMID:20509684

  12. Solubility and first hydrolysis constants of europium at different ionic strength and 303 K

    International Nuclear Information System (INIS)

    The solubility of europium at 0.02M, 0.1M and 0.7M NaClO4 ionic strength solutions was determined by a radiometric method and pEus-pCH diagrams were obtained. Hydrolysis constants were also determined at the same ionic strengths by pH titration and the values found were log *β1 -7.68±0.11, -8.07±0.10 and -8.20±0.11. The log Ksp values were -23.5±0.2, -22.7±0.2 and -21.9±0.2 for 0.02M, 0.1M and 0.7M NaClO4 ionic strengths, respectively, at 303 K under CO2-free conditions and the extrapolated value at zero ionic strength was log Ksp0 = -24.15. The working pCH ranges for the calculation of the hydrolysis constants were selected from the pEus-pCH diagrams in the region where precipitation of europium oxide or hydroxide was less than 20%. Europium removal from aqueous solutions with zeolites was explored. (author)

  13. Phase Transitions of Triflate-Based Ionic Liquids under High Pressure.

    Science.gov (United States)

    Faria, Luiz F O; Ribeiro, Mauro C C

    2015-11-01

    Raman spectroscopy has been used to study phase transitions of ionic liquids based on the triflate anion, [TfO](-), as a function of pressure or temperature. Raman spectra of ionic liquids containing the cations 1-butyl-3-methylimidazolium, [C4C1Im](+), 1-octyl-3-methylimidazolium, [C8C1Im](+), 1-butyl-2,3-dimethylimidazolium, [C4C1C1Im](+), and 1-butyl-1-methylpyrrolidinium, [C4C1Pyr](+), were compared. Vibrational frequencies and binding energy of ionic pairs were calculated by quantum chemistry methods. The ionic liquids [C4C1Im][TfO] and [C4C1Pyr][TfO] crystallize at 1.0 GPa when the pressure is increased in steps of ∼ 0.2 GPa from the atmospheric pressure, whereas [C8C1Im][TfO] and [C4C1C1Im][TfO] do not crystallize up to 2.3 GPa of applied pressure. The low-frequency range of the Raman spectrum of [C4C1Im][TfO] indicates that the system undergoes glass transition, rather than crystallization, when the pressure applied on the liquid has been increased above 2.0 GPa in a single step. Strong hysteresis of spectral features (frequency shift and bandwidth) of the high-pressure crystalline phase when the pressure was released stepwise back to the atmospheric pressure has been found . PMID:26457868

  14. Self-consistent field theory of polymer-ionic molecule complexation.

    Science.gov (United States)

    Nakamura, Issei; Shi, An-Chang

    2010-05-21

    A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, C(i) ((a))(kDelta)(=0 or 1), whose average determines the number of adsorbed molecules, n(BI). Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for n(BI) are obtained, depending on the equilibrium constant of single-ion binding. Spinodal lines calculated from the mean-field free energy exhibit closed-loop regions where the homogeneous phase becomes unstable. This phase instability is driven by the excluded-volume interaction due to the single occupancy of ion-binding sites on the polymers. Moreover, sol-gel transitions are examined using a critical degree of conversion. A gel phase is induced when the concentration of adsorbates is increased. At a higher concentration of the adsorbates, however, a re-entrance from a gel phase into a sol phase arises from the correlation between unoccupied and occupied ion-binding sites. The theory is applied to a model system, poly(vinyl alcohol) and borate ion in aqueous solution with sodium chloride. Good agreement between theory and experiment is obtained. PMID:20499947

  15. Ethanol extraction from its azeotropic mixture with hexane employing different ionic liquids as solvents

    International Nuclear Information System (INIS)

    Highlights: ► Several ionic liquids were investigated as solvents to extract ethanol from hexane. ► Determination of LLE for the ternary systems was carried out at T = 298.15 K. ► Structural influence of the ionic liquids on the extraction process was analyzed. ► Experimental LLE data were correlated by means of the NRTL and UNIQUAC models. - Abstract: In this work, the ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMim][NTf2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMim][NTf2], 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, [BMpy][NTf2], 1-butyl-3-methylpyridinium trifluoromethanesulfonate, [BMpy][TfO], have been investigated for their use as solvents in extraction processes for the ethanol removal from its azeotropic mixture with hexane. Therefore, the experimental determination of the liquid + liquid equilibrium for the ternary systems {hexane (1) + ethanol (2) + [EMim][NTf2] (3)}, {hexane (1) + ethanol (2) + [BMim][NTf2] (3)}, {hexane (1) + ethanol (2) + [BMpy][NTf2] (3)} and {hexane (1) + ethanol (2) + [BMpy][TfO] (3)} was carried out at T = 298.15 K and atmospheric pressure. Classical parameters such as selectivity and solute distribution ratio, derived from the tie-line data, were calculated and afterwards, the structural influence of the ionic liquids on the extraction process was analyzed. Finally, the experimental LLE data were correlated by means of the NRTL and UNIQUAC models.

  16. Triggering the Chemical Instability of an Ionic Liquid under High Pressure.

    Science.gov (United States)

    Faria, Luiz F O; Nobrega, Marcelo M; Temperini, Marcia L A; Bini, Roberto; Ribeiro, Mauro C C

    2016-09-01

    Ionic liquids are an interesting class of materials due to their distinguished properties, allowing their use in an impressive range of applications, from catalysis to hypergolic fuels. However, the reactivity triggered by the application of high pressure can give rise to a new class of materials, which is not achieved under normal conditions. Here, we report on the high-pressure chemical instability of the ionic liquid 1-allyl-3-methylimidazolium dicyanamide, [allylC1im][N(CN)2], probed by both Raman and IR techniques and supported by quantum chemical calculations. Our results show a reaction occurring above 8 GPa, involving the terminal double bond of the allyl group, giving rise to an oligomeric product. The results presented herein contribute to our understanding of the stability of ionic liquids, which is of paramount interest for engineering applications. Moreover, gaining insight into this peculiar kind of reactivity could lead to the development of new or alternative synthetic routes to achieve, for example, poly(ionic liquids). PMID:27470147

  17. Charge transfer in ionic systems

    International Nuclear Information System (INIS)

    process is shown to be dominant on the N3+(2p2)1S single capture channel, but the double capture process has to be taken into account in the mechanism. The semi-classical approach may be extended to molecular targets, taking account of the much higher velocity of electronic transitions, with respect to molecular vibration. At the lower level of approximation, the molecular vibration of the molecule can be ignored and the ion-molecule collision may be visualized as an ion bumping an anisotropic atom. This approach has been applied on the B3+(1s2) + H2 and give reasonable results for energies greater than 100 eV/amu, taking account of the anisotropy effect for the different orientations of the molecule and the dependence on the vibrational coordinate rH-H. The wave-packet time-dependent treatment has been developed on the Si4+ + He collisional system. The recombination of silicon ions with atomic hydrogen and helium is a quite important process in astrophysical plasma which has attracted recently a particular interest as experiments of Fang and Kwong have provided for the first time measurements of rate constants at very low temperatures. The calculation has been performed in both adiabatic and diabatic representations in order to get rid of the ambiguity in defining the unitary transformation, in particular for polyatomic systems and Hackel-Ricatti functions have been used in order to improve the precision of the calculations. Our results are in good agreement with time independent approaches, but a large discrepancy is observed with the ion-trap experiment of Kwong which cannot be explained by the simple electron exchange Si4+/Si3+. Further mechanisms involving impurities or excited states should perhaps be considered. (author)

  18. Furfural production using ionic liquids: A review.

    Science.gov (United States)

    Peleteiro, Susana; Rivas, Sandra; Alonso, José Luis; Santos, Valentín; Parajó, Juan Carlos

    2016-02-01

    Furfural, a platform chemical with a bright future, is commercially obtained by acidic processing of xylan-containing biomass in aqueous media. Ionic liquids (ILs) can be employed in processed for furfural manufacture as additives, as catalysts and/or as reaction media. Depending on the IL utilized, externally added catalysts (usually, Lewis acids, Brönsted acids and/or solid acid catalysts) can be necessary to achieve high reaction yields. Oppositely, acidic ionic liquids (AILs) can perform as both solvents and catalysts, enabling the direct conversion of suitable substrates (pentoses, pentosans or xylan-containing biomass) into furfural. Operating in IL-containing media, the furfural yields can be improved when the product is continuously removed along the reaction (for example, by stripping or extraction), to avoid unwanted side-reactions leading to furfural consumption. These topics are reviewed, as well as the major challenges involved in the large scale utilization of ILs for furfural production. PMID:26708486

  19. Ionic conduction in the solid state

    Indian Academy of Sciences (India)

    P Padma Kumar; S Yashonath

    2006-01-01

    Solid state ionic conductors are important from an industrial viewpoint. A variety of such conductors have been found. In order to understand the reasons for high ionic conductivity in these solids, there have been a number of experimental, theoretical and computational studies in the literature. We provide here a survey of these investigations with focus on what is known and elaborate on issues that still remain unresolved. Conductivity depends on a number of factors such as presence of interstitial sites, ion size, temperature, crystal structure etc. We discuss the recent results from atomistic computer simulations on the dependence of conductivity in NASICONs as a function of composition, temperature, phase change and cation among others. A new potential for modelling of NASICON structure that has been proposed is also discussed.

  20. Magnetic microemulsions based on magnetic ionic liquids.

    Science.gov (United States)

    Klee, Andreas; Prevost, Sylvain; Kunz, Werner; Schweins, Ralf; Kiefer, Klaus; Gradzielski, Michael

    2012-11-28

    Microemulsions with magnetic properties were formed by employing a magnetic room temperature ionic liquid (MRTIL) as polar phase, cyclohexane as oil, and an appropriate mixture of ionic surfactant and decanol as a cosurfactant. By means of small-angle neutron scattering (SANS) and electric conductivity the microemulsion structure could be confirmed, where the classical structural sequence of oil-continuous-bicontinuous-polar phase continuous is observed with increasing ratio [polar phase]/[oil]. Accordingly a maximum of the structural size is observed at about equal volumes of oil and MRTIL contained. Therefore this system is structurally the same as normal microemulsions but with the magnetic properties added to it by the incorporation into the systems formulation. PMID:23060241

  1. Dynamics of Ion Transport in Ionic Liquids.

    Science.gov (United States)

    Lee, Alpha A; Kondrat, Svyatoslav; Vella, Dominic; Goriely, Alain

    2015-09-01

    A gap in understanding the link between continuum theories of ion transport in ionic liquids and the underlying microscopic dynamics has hindered the development of frameworks for transport phenomena in these concentrated electrolytes. Here, we construct a continuum theory for ion transport in ionic liquids by coarse graining a simple exclusion process of interacting particles on a lattice. The resulting dynamical equations can be written as a gradient flow with a mobility matrix that vanishes at high densities. This form of the mobility matrix gives rise to a charging behavior that is different to the one known for electrolytic solutions, but which agrees qualitatively with the phenomenology observed in experiments and simulations. PMID:26382685

  2. Structure of room temperature ionic liquids.

    Science.gov (United States)

    Yethiraj, Arun

    2016-10-19

    The structure of room temperature ionic liquids is studied using molecular dynamics simulations and integral equation theory. Three ionic liquids 1-alkyl-3-methylimidazolium hexfluorophosphate, [C n MIM] [PF6], for n  =  1, 4, and 8, are studied using a united atom model of the ions. The primary interest is a study of the pair correlation functions and a test of the reference interaction site model theory. There is liquid-like ordering in the liquid that arises from electrostatic attractions and steric packing considerations. The theory is not in quantitative agreement with the simulation results and underestimates the degree of liquid-like order. A pre-peak in the static structure factor is seen in both simulations and theory, suggesting that this is a geometric effect arising from a packing of the alkyl chains. PMID:27546807

  3. Many-body effects in ionic systems

    OpenAIRE

    Wilson, Mark; Madden, Paul A.; Paul Madden

    1994-01-01

    The electron density of an ion is strongly influenced by its environment in a condensed phase. When the environment changes, for example due to thermal motion, non-trivial changes in the electron density, and hence the interionic interactions occur. These interactions give rise to many-body effects in the potential. In order to represent this phenomenon in molecular dynamics (MD) simulations a method has been developed in which the environmentally-induced changes in the ionic p...

  4. Interfacial properties of charge asymmetric ionic liquids

    OpenAIRE

    Alejandre, Jose; Bresme, Fernando; Gonzalez-Melchor, Minerva

    2009-01-01

    We report molecular dynamics simulations of the coexistence and interfacial properties of ionic liquids as a function of cation/anion, (z$_+$ : z$_-$) = (2:-1), (4:-1), charge asymmetry. Our results correct previous computations of the coexistence curve of (2:-1) charge asymmetric systems, obtained via the fine-lattice discretization method. In agreement with previous computations we report a reduction in the critical temperature and an increase in the critical density with charge asymmetry. ...

  5. Supported ionic liquids fundamentals and applications

    CERN Document Server

    Fehrmann, Rasmus; Haumann, Marco

    2013-01-01

    This unique book gives a timely overview about the fundamentals and applications of supported ionic liquids in modern organic synthesis. It introduces the concept and synthesis of SILP materials and presents important applications in the field of catalysis (e.g. hydroformylation, hydrogenation, coupling reactions, fine chemical synthesis) as well as energy technology and gas separation. Written by pioneers in the field, this book is an invaluable reference book for organic chemists in academia or industry.

  6. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  7. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2004-12-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.

  8. Interatomic Potential Models for Ionic Materials

    Science.gov (United States)

    Gale, Julian D.

    Ionic materials are present in many key technological applications of the modern era, from solid state batteries and fuel cells, nuclear waste immobiliza tion, through to industrial heterogeneous catalysis, such as that found in automotive exhaust systems. With the boundless possibilities for their utilization, it is natural that there has been a long history of computer simulation of their structure and properties in order to understand the materials science of these systems at the atomic level.

  9. Interfacial properties of charge asymmetric ionic liquids

    OpenAIRE

    2009-01-01

    Abstract We report molecular dynamics simulations of the coexistence and interfacial properties of ionic liquids as a function of cation/anion, (z$_+$ : z$_-$) = (2:-1), (4:-1), charge asymmetry. Our results correct previous computations of the coexistence curve of (2:-1) charge asymmetric systems, obtained via the fine-lattice discretization method. In agreement with previous computations we report a reduction in the critical temperature and an increase in the critical density wit...

  10. Ionic Vapor Composition in Critical and Supercritical States of Strongly Interacting Ionic Compounds.

    Science.gov (United States)

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-05-12

    The critical point, CP (T, P), of the phase diagram quantifies the minimum amount of kinetic energy needed to prevent a substance from existing in a condensed phase. Therefore, the CP is closely related to the properties of the fluid far below the critical temperature. Approaches designed to predict thermophysical properties of a system necessarily aim to provide reliable estimates of the CP. Vice versa, CP estimation is impossible without knowledge of the vapor phase behavior. We report ab initio Born-Oppenheimer molecular dynamics (BOMD) simulations of sodium and potassium chlorides, NaCl and KCl, at and above their expected CPs. We advance the present knowledge regarding the existence of ionic species in the vapor phase by establishing significant percentages of atomic clusters: 29-30% in NaCl and 34-38% in KCl. A neutral pair of counterions is the most abundant cluster in the ionic vapors (ca. 35% of all vaporized ions exist in this form). Unexpectedly, an appreciable fraction of clusters is charged. The ionic vapor composition is determined by the vapor density, rather than the nature of the alkali ion. The previously suggested CPs of NaCl and KCl appear overestimated, based on the present simulations. The reported results offer essential insights into the ionic fluid properties and assist in development of thermodynamic theories. The ab initio BOMD method has been applied to investigate the vapor phase composition of an ionic fluid for the first time. PMID:27100933

  11. Ionic Conductivity and Gas Permeability of Polymerized Ionic Liquid Block Copolymer Membranes

    Science.gov (United States)

    Evans, Christopher; Sanoja, Gabriel; Schneider, Yanika; Modestino, Miguel; Segalman, Rachel; Joint CenterArtificial Photosynthesis Team

    2014-03-01

    Polymer membranes for many energy applications, such as solar-to-hydrogen fuel production, require ionic conductivity while acting as gas diffusion barriers. We have synthesized a diblock copolymer consisting of poly(styrene-block-(4-(2-methacrylamidoethyl)-imidazolium trifluoroacetate) by treating poly(styrene-block-histamine methacrylamide) (PS- b-PHMA) with trifluoroacetic acid. The PS block serves as the structural support while the imidazolium derivative is an ion conducting polymerized ionic liquid (PIL). Small angle X-ray scattering and transmission electron microscopy demonstrate that the block copolymer self-assembles into well-ordered nanostructures, with lamellae and hexagonally packed cylindrical morphologies. The ionic conductivities of the PS-b-PHMA materials were as high as 2 x 10-4 S/cm while an order of magnitude increase in conductivity was observed upon conversion to PS-b-PIL. The ionic conductivity of the PS-b-PIL increased by a factor of ~ 4 up to 1.2 x 10-3 S/cm as the PIL domain size increased from 20 to 40 nm. These insights allow for the rational design of high performance ion conducting membranes with even greater conductivities via precise morphological control. Additionally, the role of thermal annealing on the ionic conductivity and gas permeability of copolymer membranes was investigated.

  12. Activation of blood clotting and fibrinolysis in angiocardiography with ionic and non-ionic contrast medium

    International Nuclear Information System (INIS)

    Purpose: To study the effects of a ionic (amidotrizoate) and a nonionic X-ray contrast medium (iopromid) during routine levocardiography and coronary angiography, we employed assays that detect reaction products of thrombin and plasmin to assess the activation of the haemostatic system. Methods: Subsequent to informed consent, 20 patients were randomly assigned to receive either amidotrizoate or iopromid during standard levocardiography and coronary angiography in a double-blind comparative study. Groups were comparable in respect of age, weight, sex and severity of the disease. No anticoagulation was provided. Coronary angiography was performed according to a standardised protocol. Consumption of contrast media and duration of the examination were comparable in both groups. Results: Thrombin generation (F.1+2) and thrombin activity (TAT) were higher with the ionic contrast medium but did not attain statistical significance. Fibrin generation and degradation as expressed by D-dimer fibrin split products was significantly increased in patients who had been receiving amidotrizoate (p<0,05, U-Test). Conclusion: The non-ionic X-ray contrast medium induced significantly less haemostatic activation in vivo than did the ionic medium amidotrizoate. These data suggest that earlier in vitro observations of more pronounced anticoagulant effects of ionic X-ray contrast media are of limited significance for the evaluation of in vivo effects of X-ray contrast media on haemostatic function. (orig.)

  13. Antimicrobial Ionic Liquids with Fumarate Anion

    Directory of Open Access Journals (Sweden)

    Biyan He

    2013-01-01

    Full Text Available The shortage of new antimicrobial drugs and increasing resistance of microbe to antimicrobial agents have been of some concern. The formulation studies of new antibacterial and antifungal agents have been an active research field. Ionic liquids are known as designed liquids with controllable physical/chemical/biological properties and specific functions, which have been attracting considerable interest over recent years. However, no attention has been made towards the preparation of ionic liquids with antimicrobial activities. In this paper, a new class of ionic liquids (ILs with fumarate anion was synthesized by neutralization of aqueous 1-butyl-3-methylimidazolium hydroxide with equimolar monoester fumarate and characterized using NMR and thermal gravimetric analysis. The ILs are soluble in water and polar organic solvents and also soluble in the common ILs. The antimicrobial activities of the ILs are more active than commercially available potassium sorbate and are greatly affected by the alkyl chain length. The significant antimicrobial properties observed in this research suggest that the ILs may have potential applications in the modern biotechnology.

  14. Ionic Block Copolymers for Anion Exchange Membranes

    Science.gov (United States)

    Tsai, Tsung-Han; Herbst, Dan; Giffin, Guinevere A.; di Noto, Vito; Witten, Tom; Coughlin, E. Bryan

    2013-03-01

    Anion exchange membrane (AEM) fuel cells have regained interest because it allows the use of non-noble metal catalysts. Until now, most of the studies on AEM were based on random polyelectrolytes. In this work, Poly(vinylbenzyltrimethylammonium bromide)-b- (methylbutylene) ([PVBTMA][Br]-b-PMB) was studied by SAXS, TEM and dielectric spectroscopy to understand the fundamental structure-conductivity relationship of ion transport mechanisms within well-ordered block copolymers. The ionic conductivity and the formation of order structure were dependent on the casting solvent. Higher ion exchange capacity (IEC) of the membranes showed higher conductivity at as IEC values below 1.8mmol/g, as above this, the ionic conductivity decreases due to more water uptake leading to dilution of charge density. The humidity dependence of morphology exhibited the shifting of d-spacing to higher value and the alteration in higher characteristic peak of SAXS plot as the humidity increase from the dry to wet state. This phenomenon can be further explained by a newly developed polymer brush theory. Three ionic conduction pathways with different conduction mechanism within the membranes can be confirmed by broadband electric spectroscopy. US Army MURI (W911NF1010520)

  15. Canopy Dynamics in Nanoscale Ionic Materials

    KAUST Repository

    Jespersen, Michael L.

    2010-07-27

    Nanoscale ionic materials (NIMS) are organic - inorganic hybrids in which a core nanostructure is functionalized with a covalently attached corona and an ionically tethered organic canopy. NIMS are engineered to be liquids under ambient conditions in the absence of solvent and are of interest for a variety of applications. We have used nuclear magnetic resonance (NMR) relaxation and pulse-field gradient (PFG) diffusion experiments to measure the canopy dynamics of NIMS prepared from 18-nm silica cores modified by an alkylsilane monolayer possessing terminal sulfonic acid functionality, paired with an amine-terminated ethylene oxide/propylene oxide block copolymer canopy. Carbon NMR studies show that the block copolymer canopy is mobile both in the bulk and in the NIMS and that the fast (ns) dynamics are insensitive to the presence of the silica nanoparticles. Canopy diffusion in the NIMS is slowed relative to the neat canopy, but not to the degree predicted from the diffusion of hard-sphere particles. Canopy diffusion is not restricted to the surface of the nanoparticles and shows unexpected behavior upon addition of excess canopy. Taken together, these data indicate that the liquid-like behavior in NIMS is due to rapid exchange of the block copolymer canopy between the ionically modified nanoparticles. © 2010 American Chemical Society.

  16. The calculation of thermophysical properties of nickel plasma

    International Nuclear Information System (INIS)

    The thermophysical properties of Nickel plasma have been calculated for the temperatures 10–60 kK and densities less than 1 g/cm3. These properties are the pressure, internal energy, heat capacity, and the electronic transport coefficients (electrical conductivity, thermal conductivity, and thermal power). The thermodynamic values have been calculated by means of the chemical model, which also allows one to obtain the ionic composition of considered plasma. The composition has been used to calculate the electronic transport coefficients within the relaxation time approximation. The results of the present investigation have been compared with the calculations of other researchers and available data of measurements

  17. Ionic strength and pH dependence of binding of Am(III)- and Eu(III)-humates

    International Nuclear Information System (INIS)

    Binding constants of Eu(III)- and Am(III)- complexes with soil-derived humic acid were determined by solvent extraction at various pH and ionic strength. Based on the dependence of binding constants on pH and ionic strength, stabilities of the humate complexes in land water and seawater were estimated. Speciation calculation based on the binding constants indicated that Am(III) could combine with humic substances in natural water system. (author) 17 refs.; 3 figs.; 2 tabs

  18. Hydrolysis, formation and ionization constants at 25/sup 0/C, and at high temperature-high ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, S.L.; Phillips, C.A.; Skeen, J.

    1985-02-01

    Thermochemical data for nuclear waste disposal are compiled. The resulting computerized database consists of critically evaluated data on Gibbs energy of formation, enthalpy of formation, entropy and heat capacity of selected substances for about 16 elements at 25/sup 0/C and zero ionic strength. Elements covered are Am, As, Br, C, Cl, F, I, Mo, Np, N, O, P, Pu, Si, Sr, S, and U. Values of these thermodynamic properties were used to calculate equilibrium quotients for hydrolysis, complexation and ionization reactions up to 300/sup 0/C and 3 ionic strength, for selected chemical reactions.

  19. 2012 Gordon Research Conference On Molecular And Ionic Clusters

    International Nuclear Information System (INIS)

    The Gordon Research Conference on 'Molecular and Ionic Clusters' focuses on clusters, which are the initial molecular species found in gases when condensation begins to occur. Condensation can take place solely from molecules interacting with each other, mostly at low temperatures, or when molecules condense around charged particles (electrons, protons, metal cations, molecular ions), producing ion molecule clusters. These clusters provide models for solvation, allow a pristine look at geometric as well as electronic structures of molecular complexes or matter in general, their interaction with radiation, their reactivity, their thermodynamic properties and, in particular, the related dynamics. This conference focuses on new ways to make clusters composed of different kinds of molecules, new experimental techniques to investigate the properties of the clusters and new theoretical methods with which to calculate the structures, dynamical motions and energetics of the clusters. Some of the main experimental methods employed include molecular beams, mass spectrometry, laser spectroscopy (from infrared to XUV; in the frequency as well as the time domain) and photoelectron spectroscopy. Techniques include laser absorption spectroscopy, laser induced fluorescence, resonance enhanced photoionization, mass-selected photodissociation, photofragment imaging, ZEKE photoelectron spectroscopy, etc. From the theoretical side, this conference highlights work on potential surfaces and measurable properties of the clusters. The close ties between experiment, theory and computation have been a hallmark of the Gordon Research Conference on Molecular and Ionic Clusters. In the 2012 meeting, we plan to have sessions that will focus on topics including: (1) The use of cluster studies to probe fundamental phenomena; (2) Finite size effects on structure and thermodynamics; (3) Intermolecular forces and cooperative effects; (4) Molecular clusters as models for solvation; and (5) Studies of

  20. QC-DMRG study of the ionic--neutral curve crossing of LiF

    OpenAIRE

    Legeza, Ö.; R{ö}der, J.; Hess, B. A.

    2002-01-01

    We have studied the ionic--neutral curve crossing between the two lowest ^1 Sigma^+ states of LiF in order to demonstrate the efficiency of the quantum chemistry version of the density matrix renormalization group method (QC-DMRG). We show that QC-DMRG is capable to calculate the ground and several low-lying excited state energies within the error margin set up in advance of the calculation, while with standard quantum chemical methods it is difficult to obtain a good approximation to Full CI...

  1. Use of ionic model for analysis of intramolecular movement in alkali metal metaborate molecules

    International Nuclear Information System (INIS)

    To clear out the peculiarities of intramolecular movement in MBO2 (where M=Li, Na, K, Rb, Cs) molecules the energy dependence of cation electrostatic interaction with BO2 anion on the charge value of oxygen, values of the MOB valence angle and internuclear distance r(M-O) is calculated. The calculation results on the base of ionic model show that the minimum of potential energy function corresponds to angular configuration of the MBO2 molecules. Parameters of potential function of deformation oscillation connected with the change of MOB angle, are evaluated

  2. Average Distribution of Ionic Charges and Ionizability for the Au Plasma System

    Institute of Scientific and Technical Information of China (English)

    杨天丽; 蒋刚; 朱正和

    2002-01-01

    Using relativistic multi-configuration Dirac-Fock theory, we calculate the transition data of 3dj - n fj, (n =5, 6, 7) for the M-shell from an Ni-like Au ion to an As-like Auion using the GRASP programme with the core-polarization, quantum electrodynamical effect and Breit correction. Based on the present calculation results andthe experiment of the Xingguang-Ⅱ laser facilities, the average distribution of ionic charge and the ionizabilityhave been derived. The average ionization degree of Au plasma Z* is 49.06 ± 0.5, which is comparable with theresult of the Lawrence Livermore National Laboratory.

  3. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  4. Ionic equilibrium between octahedral and tetrahedral complexes in liquid aluminium-sodium fluoride mixtures

    International Nuclear Information System (INIS)

    An earlier statistical mechanical theory of complexing in molten mixtures of polyvalent metal halides and alkali halides is extended to situations in which an ionic equilibrium is established between two different types of complexes. The specific systems of interest are the mixtures of aluminium fluoride and sodium fluoride, in which early Raman scattering experiments by Gilbert, Mamantov and Begun have demonstrated coexistence of octahedral (AlF6)3- units and tetrahedral (AlF4)- units in the concentration range between 0.25 and 0.5 of AlF3. Our treatment is based on a simple ionic model and involves (i) an evaluation of binding free energies for the two units in vacuo, showing that (AlF6)3- is strongly unstable against dissociation in this state, and (ii) a statistical mechanical theory of the liquid mixture, in which (AlF6)3- is stabilized by ionic screening interactions. The resulting ionic equilibrium in the liquid involves, in excellent agreement with the Raman data, strong suppression of dissociation for (AlF6)3-, except near the composition corresponding to criolite (AlF3.3NaF). The temperature dependence of the ionic equilibrium is also evaluated, with special attention to molten criolite. Analogous calculations on aluminium-sodium chloride mixtures show that in these systems the equilibrium is completely shifted in favour of the (AlCl4)- species, as a consequence of its stabilization by halogen polarizability. (author). 13 refs, 1 fig., 4 tabs

  5. (Solid + liquid) equilibria predictions of ionic liquid containing systems using COSMO-RS

    International Nuclear Information System (INIS)

    Highlights: ► (Solid + liquid) equilibria (SLE) prediction on IL systems. ► Use of COSMO-RS model. ► Quantitative agreement with effect of temperature. - Abstract: (Solid + liquid) equilibria (SLE) prediction are an important phase equilibria property for ionic liquid (IL) mixtures especially when the IL exists as a solid. In this work, the SLE for the binary systems of (IL + thiophene) consisting of the ILs: n-butyl-4-methylpyridinium tosylate [BM4Py][TOS], n-butyl-3-methylpyridinium tosylate [BM3Py][TOS], n-hexyl-3-methylpyridinium tosylate [HM3Py][TOS], and 1,4-dimethylpyridinium tosylate [M1,4Py][TOS] are predicted using the quantum chemical based COSMO-RS (COnductor like Screening MOdel for Real Solvents) model. Initially, benchmarking studies are performed on binary mixtures which are known beforehand. The values of the predicted solubility are then compared with the experimental results by calculating the root mean square error (RMSE). The SLE predictions of the solubility of pyrene and dibenzothiophene in five different solvents were carried out giving an average RMSE of 4%. Further the applicability of COSMO-RS to binary systems consisting of (ionic liquid + alcohol) mixtures and (ionic liquid + hydrocarbons) are predicted. The ionic liquids concerned are n-butyl-3-methylpyridinium tosylate [BM3Py][TOS] while the alcohols and hydrocarbons are 1-butanol, 1-hexanol, 1-octanol, 1-decanol, and benzene, toluene, ethylbenzene, n-propylbenzene respectively. The experimental data for the ionic liquid [BM4Py][TOS] with thiophene gave the smallest deviation of 10.2%. The overall RMSE for IL–thiophene, IL–alcohol, and IL–hydrocarbons were 15%, 17.2% and 12.9% respectively. Thus the predicted solubility values were found to be in reasonable agreement with the experimental values.

  6. Competition between the ionic and covalent character in the series of boron compounds BP, BAs, and BSb

    International Nuclear Information System (INIS)

    We present first-principles calculations of the bonding properties for the series of boron compounds BP, BAs, and BSb. The plane-wave pseudopotential approach to density functional theory in the local density approximation has been used to calculate the equilibrium properties, i.e., the ground-state energy, the lattice constant, the bulk modulus, its pressure derivative, and the ionicity factor. The valence electron density is used to study the modification of the bonding with respect to different pressures. The calculated electronic charge densities present an anomalous behaviour which can be characterized by reversing the standard assignments for the anion and cation in these compounds. The competition between the ionic and the covalent character in these materials is discussed in relation to the charge transfer. Estimates of the ionicity and its pressure derivative for the series of boron compounds are presented. The distribution of the valence charge density suggests that the bonding in these materials is less ionic than in other zinc-blende compounds. (author)

  7. Theoretical and Experimental Study of the Friction Behavior of Halogen-Free Ionic Liquids in Elastohydrodynamic Regime

    Directory of Open Access Journals (Sweden)

    Karthik Janardhanan

    2016-05-01

    Full Text Available Ionic Liquids have emerged as effective lubricants and additives to lubricants, in the last decade. Halogen-free ionic liquids have recently been considered as more environmentally stable than their halogenated counterparts, which tend to form highly toxic and corrosive acids when exposed to moisture. Most of the studies using ionic liquids as lubricants or additives of lubricants have been done experimentally. Due to the complex nature of the lubrication mechanism of these ordered fluids, the development of a theoretical model that predicts the ionic liquid lubrication ability is currently one of the biggest challenges in tribology. In this study, a suitable and existing friction model to describe lubricating ability of ionic liquids in the elastohydrodynamic lubrication regime is identified and compared to experimental results. Two phosphonium-based, halogen-free ionic liquids are studied as additives to a Polyalphaolefin base oil in steel–steel contacts using a ball-on-flat reciprocating tribometer. Experimental conditions (speed, load and roughness are selected to ensure that operations are carried out in the elastohydrodynamic regime. Wear volume was also calculated for tests at high speed. A good agreement was found between the model and the experimental results when [THTDP][Phos] was used as an additive to the base oil, but some divergence was noticed when [THTDP][DCN] was added, particularly at the highest speed studied. A significant decrease in the steel disks wear volume is observed when 2.5 wt. % of the two ionic liquids were added to the base lubricant.

  8. Effect of ionic and non-ionic contrast media on red cell aggregation in vitro

    International Nuclear Information System (INIS)

    The effect of solutions of the ionic contrast media diatrizoate, iocarmate, and metrizoate and the non-ionic metrizamide on red cell aggregation in vitro was examined. The aggregation was recorded by both microphotography and photometry in a counter-rotating rheoscope chamber. All the contrast media decreased the formation of red cell aggregates. This desaggregating ability increased with both increasing volume ratio (contrast media/blood) and with increasing osmolality of the contrast media. The desaggregating effect was also obtained with the contrast media solutions isotonic with blood. The iocarmate and diatrizoate solutions induced less reduction in red cell aggregation than the metrizoate and metrizamide solutions. (Auth.)

  9. Atomic-scale configurations of synchroshear-induced deformation twins in the ionic MnS crystal

    Science.gov (United States)

    Zhou, Y. T.; Xue, Y. B.; Chen, D.; Wang, Y. J.; Zhang, B.; Ma, X. L.

    2014-01-01

    Deformation twinning was thought as impossible in ionic compounds with rock-salt structure due to the charge effect on {111} planes. Here we report the presence and formation mechanism of deformation {111} twins in the rock-salt manganese sulphide (MnS) inclusions embedded in a hot-rolled stainless steel. Based on the atomic-scale mapping under aberration-corrected scanning transmission electron microscopy, a dislocation-based mechanism involved two synchronized shear on adjacent atomic layers is proposed to describe the dislocation glide and consequently twinning formation. First-principles calculations of the energy barriers for twinning formation in MnS and comparing with that of PbS and MgO indicate the distinct dislocation glide scheme and deformation behaviors for the rock-salt compounds with different ionicities. This study may improve our understanding of the deformation mechanisms of rock-salt crystals and other ionic compounds. PMID:24874022

  10. Transport Properties of Multivalent Cations in Nafion-117 Membrane with Mixed Ionic Composition.

    Science.gov (United States)

    Chaudhury, Sanhita; Agarwal, Chhavi; Goswami, A

    2015-08-20

    The transport characteristics of multivalent cations like Ba(2+) and Eu(3+) have been studied in bi-ionic form of the Nafion-117 membrane. The membranes have been prepared by loading different proportions of H(+)-Ba(2+)/Mg(2+)-Ba(2+)/Ba(2+)-Eu(3+)/H(+)-Eu(3+)/Na(+)-Eu(3+). The cationic compositions of the membranes have been determined from the measured ion exchange isotherms. Results show that the self-diffusion coefficient of Ba(2+) (D(Ba)) in H-Ba/Mg-Ba systems as well as the self-diffusion coefficient of Eu(3+) (D(Eu)) in H-Eu/Na-Eu systems are strongly dependent on the membrane ionic compositions and decreased continuously with increasing concentration of the highly hydrated ions (H(+)/Na(+)/Mg(2+)) in the membrane. Increase in the proportion of H(+)/Na(+)/Mg(2+) ions in the membrane increases the effective charge on the membrane matrix. This causes stronger electrostatic interaction of the less hydrated multivalent ions (Ba(2+)/Eu(3+)) with the membrane matrix charges, which ultimately results in their slower self-diffusion coefficients. The higher the valence, the stronger the electrostatic interaction is with the fixed ionic charges; hence, in general, D(Eu) is affected more as compared to D(Ba). On the basis of the free-volume theory for polymers, the effective interaction potential (Φ) of the Ba(2+) with the fixed ionic sites in the membrane has been calculated and found to be on the order of approximately millivolts. The higher the proportion of hydrated ion in the membrane, the higher the Φ is and the stronger the ion pair formation is with the fixed ionic sites in the membrane. However, in the Ba-Eu system, as the electrostatic interactions of the two ions with the membrane matrix are close, D(Ba) and D(Eu) are independent of the membrane ionic composition. The ionic composition dependence of D(Ba) in the H-Ba system is reflected in the transport rate of Ba(2+), showing the importance of such measurements in understanding the transport

  11. Solubilities of some gases in four immidazolium-based ionic liquids

    International Nuclear Information System (INIS)

    Graphical abstract: Experimental apparatus based on the synthetic-volumetric method for measuring solubilities of gases in liquids. Highlights: • We constructed an apparatus for measuring solubilities of sparingly-soluble gases. • We measured solubilities of five gases in four immidazolium-based ionic liquids. • We calculated Henry’s constants for gases in the ionic liquids studied in this work. -- Abstract: The synthetic-volumetric method is used for rapidly measuring solubilities of sparingly-soluble gases in monoethylene glycol and in four ionic liquids. Known molar quantities of solute and solvent are charged into an equilibrium vessel. Measured quantities at equilibrium include: temperature, pressure, quantities of fluids, and volumes of the gas and liquid phases in the equilibrium vessel. These measurements enable calculation of equilibrium compositions using material balances. No sampling or chemical analyses are required. Solubilities are reported for carbon dioxide, krypton, oxygen, and hydrogen in monoethylene glycol, l-n-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], l-n-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][Tf2N], or 1-ethyl-3-methylimidazolium acetate [EMIM][AC]. Solubilities were measured over the temperature range (298 to 355) K and for pressures up to about 7 MPa using two different pieces of equipment, both based on the volumetric method: a low-pressure glass apparatus and a high-pressure stainless-steel apparatus. Special emphasis is given to experimental reliability to assure consistent data

  12. Confined water in imidazolium based ionic liquids: a supramolecular guest@host complex case.

    Science.gov (United States)

    Zanatta, Marcileia; Girard, Anne-Lise; Marin, Graciane; Ebeling, Gunter; Dos Santos, Francisco P; Valsecchi, Chiara; Stassen, Hubert; Livotto, Paolo R; Lewis, William; Dupont, Jairton

    2016-07-21

    It is well known that the macroscopic physico-chemical properties of ionic liquids (ILs) are influenced by the presence of water that strongly interferes with the supramolecular organization of these fluids. However, little is known about the function of water traces within this confined space and restricted ionic environments, i.e. between cations and anions. Using specially designed ILs namely 1,2,3-trimethyl-1H-imidazol-3-ium imidazol-1-ide (MMMI·Im) and 3-n-butyl-1,2-dimethyl-1H-imidazol-3-ium imidazol-1-ide (BMMI·Im), the structure and function of water have been determined in condensed, solution and gas phases by X-ray diffraction studies, NMR, molecular dynamics simulations (MDS) and DFT calculations. In the solid state the water molecule is trapped inside the ionic network (constituted of contact ion pairs formed by π(+)-π(-) interaction) through strong H-bonds involving the water hydrogens and the nitrogens of two imidazolate anions forming a guest@host supramolecular structure. A similar structural arrangement was corroborated by DFT calculations and MDS. The presence of a guest@host species (H2O@ILpair) is maintained to a great extent even in solution as detected by (1)H-(1)H NOESY-experiments of the ILs dissolved in solvents with low and high dielectric constants. This confined water catalyses the H/D exchange with other substrates containing acidic-H such as chloroform. PMID:27334927

  13. Electrochemical behavior of cobalt from 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid

    International Nuclear Information System (INIS)

    The electrodeposition of metallic cobalt from a 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was investigated. The electrochemical behavior of Co(II) in the ionic liquid on a platinum working electrode at 60 deg. C was studied by cyclic voltammetry and chronoamperometry. The results from the cyclic voltammetry showed that the electrodeposition of metallic Co in the ionic liquid was an irreversible process and controlled by the diffusion of Co(II) on a platinum working electrode. The average value of αnα was calculated to be 0.35 and the diffusion coefficient (D0) of Co(II) was calculated to be 1.76 x 10-8 cm2/s at 60 deg. C. Chronoamperometric results indicated that the electrodeposition of Co on a platinum working electrode followed the mechanism of instantaneous nucleation and three-dimensional growth with diffusion-controlled. The cobalt plating was uniform, dense, shining in appearance with good adhesion to the platinum substrate at 60 deg. C. The scanning electron microscope (SEM) micrographs were used to confirm that the cobalt plating was denser and finer at 60 deg. C. Energy dispersive X-ray analysis (EDAX) profile showed that the obtained plating was pure cobalt. X-ray diffraction (XRD) pattern indicated that there was a preferred orientation direction and the average size of cobalt grains was 40 nm.

  14. Experiment and model for the surface tension of amine–ionic liquids aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: • The surface tensions of MEA/DEA–ionic liquids aqueous solutions were measured. • The experiments were modeled satisfactorily by using a thermodynamic equation. • The temperature dependence of the surface tension was illustrated. • The effects of the mass fractions of MEA/DEA and ionic liquids were demonstrated. - Abstract: The surface tension (γ) of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4])–monoethanolamine (MEA), 1-butyl-3-methylimidazolium bromide ([Bmim][Br])–MEA, [Bmim][BF4]–diethanolamine (DEA) and [Bmim][Br]–DEA aqueous solutions was measured by using the BZY-1 surface tension meter. The temperature ranged from (293.2 to 323.2) K. The mass fraction of amines and ionic liquids (ILS) respectively ranged from 0.15 to 0.30 and 0.05 to 0.10. A thermodynamic equation was proposed to model the surface tension of amines–ILS aqueous solutions and the calculated results agreed well with the experiments. The effects of temperature, mass fraction of amines and ILS on the surface tension were demonstrated on the basis of experiments and calculations

  15. Theory and applications of atomic and ionic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Mitroy, J [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Safronova, M S [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Clark, Charles W, E-mail: jxm107@rsphysse.anu.edu.a, E-mail: msafrono@udel.ed, E-mail: charles.clark@nist.go [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, MD 20899-8410 (United States)

    2010-10-28

    Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wavefunctions, interferometry with atom beams and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards. (topical review)

  16. Theory and applications of atomic and ionic polarizabilities

    International Nuclear Information System (INIS)

    Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wavefunctions, interferometry with atom beams and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards. (topical review)

  17. TOPICAL REVIEW: Theory and applications of atomic and ionic polarizabilities

    Science.gov (United States)

    Mitroy, J.; Safronova, M. S.; Clark, Charles W.

    2010-10-01

    Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wavefunctions, interferometry with atom beams and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards.

  18. Exploring Sustainable Rocket Fuels: [Imidazolyl-Amine-BH2](+)-Cation-Based Ionic Liquids as Replacements for Toxic Hydrazine Derivatives.

    Science.gov (United States)

    Huang, Shi; Qi, Xiujuan; Zhang, Wenquan; Liu, Tianlin; Zhang, Qinghua

    2015-12-01

    The application of hypergolic ionic liquids as propellant fuels is a newly emerging area in the fields of chemistry and propulsion science. Herein, a new class of [imidazolyl-amine-BH2](+)-cation-based ionic liquids, which included fuel-rich anions, such as dicyanamide (N(CN)2(-)) and cyanoborohydride (BH3CN(-)) anions, were synthesized and characterized. As expected, all of the ionic liquids exhibited spontaneous combustion upon contact with the oxidizer 100 % HNO3. The densities of these ionic liquids varied from 0.99-1.12 g cm(-3), and the heats of formation, predicted based on Gaussian 09 calculations, were between -707.7 and 241.8 kJ mol(-1). Among them, the salt of compound 5, that is, (1-allyl-1H-imidazole-3-yl)-(trimethylamine)-dihydroboronium dicyanamide, exhibited the lowest viscosity (168 MPa s), good thermal properties (Tg 130 °C), and the shortest ignition-delay time (18 ms) with 100 % HNO3. These ionic fuels, as "green" replacements for toxic hydrazine-derivatives, may have potential applications as bipropellant formulations. PMID:26247801

  19. Atomic Resolution Insights into the Structural Aggregations and Optical Properties of Neat Imidazolium-Based Ionic Liquids.

    Science.gov (United States)

    Du, Likai; Geng, Cuihuan; Zhang, Dongju; Lan, Zhenggang; Liu, Chengbu

    2016-07-14

    A fundamental understanding of the structural heterogeneity and optical properties of ionic liquids is crucial for their potential applications in catalysis, optical measurement, and solar cells. Herein, a synergistic approach combining molecular dynamics simulations, excited-state calculations, and statistical analysis was used to explore the explicit correlation between the structural and optical properties of one imidazolium amino acid-based ionic liquid, 1-butyl-3-methylimidazolium glycine. The estimated absorption spectrum successfully rationalizes the unusual and non-negligible absorption band beyond 300 nm for the neat imidazolium-based ionic liquid. The absorption behavior of imidazolium-based ionic liquids is shown to be sensitive to the details of their locally heterogeneous environments. We quantitatively highlight the imidazolium moiety and its various molecular aggregations, rather than the monomeric imidazolium moiety, that are responsible for the absorption characteristics. These results would improve our understanding of the preliminary interplay between structural heterogeneity and optical properties for neat imidazolium-based ionic liquids. PMID:27276660

  20. Effects of pH and ionic strength on the thermodynamics of human serum albumin-photosensitizer binding

    International Nuclear Information System (INIS)

    Highlights: ► The pH dependence of entropy and enthalpy changes was determined for zinc phthalocyanine tetrasulfonic acid, ZnPcS4 binding to human serum albumin, HSA. ► The ionic strength dependence of entropy and enthalpy changes was determined for ZnPcS4 acid binding to HSA. ► The primary driving force governing the interaction between ZnPcS4 and HSA over the range of pH and ionic strength was solution dynamics. ► The interplay between entropy and enthalpy changes was demonstrated. - Abstract: Fluorescence spectroscopy was used to measure the effects of pH and ionic strength on thermodynamic parameters governing the interaction of human serum albumin with zinc phthalocyanine tetrasulfonic acid. Fluorescence emission of zinc phthalocyanine increases at 686 nm with increasing concentrations of the protein. The non-linear correlation between protein concentration and emission of the photosensitizer was fitted using Chipman's analysis to calculate the binding affinities. The standard enthalpy and entropy changes were estimated from van’t Hoff analysis of data that were acquired from temperature ramping studies. Results show that reaction is primarily driven by solution dynamics and that the change in enthalpy for the system becomes increasingly unfavorable with increasing pH and ionic strength. The effect of ionic strength on the entropy change for binding is shown to be significantly greater than the effects of pH. The interplay between entropy and enthalpy changes is demonstrated.

  1. Pink Noise of Ionic Conductance through Single Artificial Nanopore Revisted

    OpenAIRE

    Tasserit, Christophe; Koutsioubas, Alexandros; Lairez, Didier; Zalczer, Gilbert; Clochard, M.C.

    2010-01-01

    International audience We report voltage-clamp measurements through single conical nanopore obtained by chemical etching of a single ion track in polyimide film. Special attention is paid to the pink noise of the ionic current (i.e., 1=f noise) measured with different filling liquids. The relative pink-noise amplitude is almost independent of concentration and pH for KCl solutions, but varies strongly using ionic liquids. In particular, we show that depending on the ionic liquid, the trans...

  2. Supported ionic liquids: versatile reaction and separation media

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco; Wasserscheid, Peter

    The latest developments in supported ionic liquid phase (SILP) systems for catalysis and separation technology are surveyed. The SILP concept combines the advantages of homogeneous catalysis with heterogeneous process technology, and a variety of reactions have been studied where supported ionic...... liquid catalysts proved to be more active and selective than common systems. In separation applications the use of supported ionic liquids can facilitate selective transport of substrates across membranes....

  3. Ionic Liquid assisted Synthesis of Zeolite-TON

    OpenAIRE

    Tian, Yuyang; McPherson, Matthew Joseph; Wheatley, Paul Stewart; Morris, Russell Edward

    2014-01-01

    An ionic liquid assisted strategy for the synthesis of zeolitic material is reported. This strategy is a solid state synthetic method and the ionic liquid is employed as structure directing agent. A TON-type zeolite, which contains one-dimensional 10-member-ring, is successfully synthesized with the assistance of the ionic liquid, 1-ethyl-3-methylimidazolium bromide. This finding improves our understanding about the challenge of ionothermally synthesizing siliceous and aluminosilicate zeolites.

  4. Lipid Bilayer Formation in Aqueous Solutions of Ionic Liquids

    OpenAIRE

    Young, Taylor Tront

    2012-01-01

    The formation of lipid bilayer membranes between droplets of ionic liquid is presented as a means of forming functional bimolecular networks for use in sensor applications. Ionic liquids are salts that have a number of useful properties, such as low melting points making them liquid at room temperature and exceedingly low vapor pressure. Ionic liquids have seen recent popularity as environmentally friendly industrial solvent alternatives. Our research demonstrates that it is possible to cons...

  5. Soft ionization of thermally evaporated hypergolic ionic liquid aerosols

    OpenAIRE

    Koh, Christine J.

    2013-01-01

    Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1-Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably origi...

  6. Ionic liquids as a novel solvent for lanthanide extraction.

    Science.gov (United States)

    Nakashima, Kazunori; Kubota, Fukiko; Maruyama, Tatsuo; Goto, Masahiro

    2003-08-01

    Octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) dissolved in an ionic liquids, 1-butyl-3-methyl-imidazolium hexafluorophosphate, greatly enhances extractability and selectivity of lanthanide cations compared to that dissolved in conventional organic solvents; further, the recovery of lanthanides extracted into ionic liquids can be accomplished using several stripping solutions containing complexing agents. The possibility of utilizing ionic liquids as novel separation media in an industrial liquid-liquid extraction process was demonstrated. PMID:12945658

  7. Silica–enzyme–ionic liquid composites for improved enzymatic activity

    OpenAIRE

    Katsuya Kato; Yuki Kawachi; Hitomi Nakamura

    2014-01-01

    Trypsin and pepsin enzyme-catalyzed precipitation of silica, synthesized by sol–gel chemistry in an ionic liquid, produces a composite material that demonstrates high enzymatic activity. This study investigates the structural properties of this silica–enzyme–ionic liquid composite material that allows for the retention of enzyme hydrolysis and condensation activity. The composite was prepared from a mixture of organo-functionalized triethoxysilane and tetraethoxysilane in an ionic liquid via ...

  8. Modeling of aluminium deposition from chloroaluminate ionic liquids

    OpenAIRE

    Schaltin, Stijn; Ganapathi, Murugan; Binnemans, Koen; Fransaer, Jan

    2011-01-01

    A finite-element model of the electrodeposition of aluminium from chloroaluminate ionic liquids is introduced. The purpose of this model is to give an explanation for the reasonable current densities that can be achieved in chloroaluminate ionic liquids despite the fact that the electrochemically active Al2Cl7- complexes are transformed into inactive AlCl4- complexes during the electrodeposition of aluminium. The obtainable current density in the electrodeposition from chloroaluminate ionic l...

  9. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    OpenAIRE

    Hoarfrost, Megan Lane

    2012-01-01

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the additio...

  10. Electrospun nanosized cellulose fibers using ionic liquids at room temperature

    OpenAIRE

    Freire, Mara G.; Teles, Ana Rita R.; Ferreira, Rute A. S.; Carlos, Luís D.; José A. Lopes-da-Silva; Coutinho, João A. P.

    2011-01-01

    Aiming at replacing the noxious solvents commonly employed, ionic-liquid-based solvents have been recently explored as novel non-volatile and non-flammable media for the electrospinning of polymers. In this work, nanosized and biodegradable cellulose fibers were obtained by electrospinning at room temperature using a pure ionic liquid or a binary mixture of two selected ionic liquids. The electrospinning of 8 wt% cellulose in 1-ethyl-3-methylimidazolium acetate medium (a low viscosity and roo...

  11. Atmospheric Moisture Content Effects on Ionic Liquid Wettability of Alumina

    OpenAIRE

    Brittle, S.; Samuel, A; W. B. Zimmerman

    2014-01-01

    The contact angles or wettability of 7 Ionic Liquids, on an alumina substrate, have been measured under two different storage conditions. The first using a small amount of moisture content, the second with no moisture content. The contact angle of Ionic Liquid droplets on an alumina substrate were measured using an Attension Theta instrument with automated software. The results show that a small amount of moisture improves the wettability of the Ionic Liquid – alumina system and therefore sub...

  12. Hydrogen Bonding in Ionic Liquids Probed by Linear and Nonlinear Vibrational Spectroscopy

    CERN Document Server

    Roth, C; Kerlé, D; Friedriszik, F; Lütgens, M; Lochbrunner, S; Kühn, O; Ludwig, R

    2012-01-01

    Three imidazolium-based ionic liquids of the type [Cnmim][NTf2] with varying alkyl chain lengths (n = 1, 2 and 8) at the 1 position of the imidazolium ring were studied applying IR, linear Raman, and multiplex CARS spectroscopy. The focus has been on the CH-stretching region of the imidazolium ring, which is supposed to carry information about a possible hydrogen bonding network in the ionic liquid. The measurements are compared to calculations of the corresponding anharmonic vibrational spectra for a cluster of [C2mim][NTf2] consisting of four ion pairs. The results support the hypothesis of moderate hydrogen bonding involving the C(4)-H and C(5)-H groups and somewhat stronger hydrogen bonds of the C(2)-H groups.

  13. Can ionic liquids avoid third phase formation in solvent extraction?

    International Nuclear Information System (INIS)

    The undesirable third phase is generally encountered in molecular diluent systems at high metal loading concentrations. Since the ionic liquids comprise entirely of ions, the use of an ionic liquid as diluent could stabilize the polar metal-solvate in organic phase and thus could prevent the third phase formation. To confirm this the extraction behavior of Eu(III) from nitric acid medium was studied in a solution of tetra-N,N,N',N'-octyldiglycolamide (TODGA) dissolved in the ionic liquid, 1-methyl-3-octylimidazolium bis(trifluoromethansulfonyl)imide ((C8mim)(NTf2)). Our results confirmed that ionic liquids prevent undesirable third phase formation. (author)

  14. Use of ionic liquids as coordination ligands for organometallic catalysts

    Science.gov (United States)

    Li, Zaiwei; Tang, Yongchun; Cheng; Jihong

    2009-11-10

    Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

  15. Physics of transduction in ionic liquid-swollen Nafion membranes

    Science.gov (United States)

    Bennett, Matthew; Leo, Donald

    2006-03-01

    Ionic polymer transducers are a class of electroactive polymers that are able to generate large strains (1-5%) in response to low voltage inputs (1-5 V). Additionally, these materials generate electrical charge in response to mechanical strain and are therefore able to operate as soft, distributed sensors. Traditionally, ionic polymer transducers have been limited in their application by their hydration dependence. This work seeks to overcome this limitation by replacing the water with an ionic liquid. Ionic liquids are molten salts that exhibit very high thermal and electrochemical stability while also possessing high ionic conductivity. Results have shown that an ionic liquid-swollen ionic polymer transducer can operate for more than 250,000 cycles in air as compared to about 2,000 cycles for a water-swollen transducer. The current work examines the mechanisms of transduction in ionic liquid-swollen transducers based on Nafion polymer membranes. Specifically, the morphology and relevant ion associations within these membranes are investigated by the use of small-angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). These results reveal that the ionic liquid interacts with the membrane in much the same way that water does, and that the counterions of the Nafion polymer are the primary charge carriers. The results of these analyses are compared to the macroscopic transduction behavior in order to develop a model of the charge transport mechanism responsible for electromechanical coupling in these membranes.

  16. Predictions of Physicochemical Properties of Ionic Liquids with DFT

    Directory of Open Access Journals (Sweden)

    Karl Karu

    2016-07-01

    Full Text Available Nowadays, density functional theory (DFT-based high-throughput computational approach is becoming more efficient and, thus, attractive for finding advanced materials for electrochemical applications. In this work, we illustrate how theoretical models, computational methods, and informatics techniques can be put together to form a simple DFT-based throughput computational workflow for predicting physicochemical properties of room-temperature ionic liquids. The developed workflow has been used for screening a set of 48 ionic pairs and for analyzing the gathered data. The predicted relative electrochemical stabilities, ionic charges and dynamic properties of the investigated ionic liquids are discussed in the light of their potential practical applications.

  17. Improving Stability of Gasoline by Using Ionic Liquid Catalyst

    Institute of Scientific and Technical Information of China (English)

    Gao Zhirong; Liu Daosheng; Liao Kejian; Jian Heng

    2003-01-01

    The composition, characteristics and preparation of ionic liquids are presented. The factors influencing the stability of gasoline and the significance of improving gasoline stability are discussed. A novel way to improve the stability of gasoline by using ionic liquid catalyst is developed. The contents of olefin, basic nitrogen and sulfur in gasoline are determined and the optimal experimental conditions for improving gasoline stability are established.The ionic liquid catalyst, which is environmentally friendly, can reduce the olefin content in gasoline, and such process is noted for mild reaction conditions, simple operation, short reaction time, easy recycling of the ionic liquid catalyst and ready separation of products and catalyst.

  18. Method for enhancing the thermal stability of ionic compounds

    DEFF Research Database (Denmark)

    2013-01-01

    This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA.......This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA....

  19. Lipid extraction from microalgae using a single ionic liquid

    Science.gov (United States)

    Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

    2013-05-28

    A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

  20. Aprotic Heterocyclic Anion Triazolide Ionic Liquids - A New Class of Ionic Liquid Anion Accessed by the Huisgen Cycloaddition Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Robert L; Damodaran, Krishnan; Luebke, David; Nulwala, Hunaid

    2013-06-01

    The triazole core is a highly versatile heterocyclic ring which can be accessed easily with the Cu(I)-catalyzed Huisgen cycloaddition reaction. Herein we present the preparation of ionic liquids that incorporate a 1,2,3-triazolide anion. These ionic liquids were prepared by a facile procedure utilizing a base-labile pivaloylmethyl group at the 1-position, which can act as precursors to 1H- 4-substituted 1,2,3-triazole. These triazoles were then subsequently converted into ionic liquids after deprotonation using an appropriate ionic liquid cation hydroxide. The densities and thermal decompositions of these ionic liquids were measured. These novel ionic liquids have potential applications in gas separations and in metal-free catalysis.

  1. Ionic dependence of sulphur mustard cytotoxicity

    International Nuclear Information System (INIS)

    The effect of ionic environment on sulphur mustard (bis 2-chloroethyl sulphide; HD) toxicity was examined in CHO-K1 cells. Cultures were treated with HD in different ionic environments at constant osmolar conditions (320 mOsM, pH 7.4). The cultures were refed with fresh culture medium 1 h after HD exposure, and viability was assessed. Little toxicity was apparent when HD exposures were carried out in ion-free sucrose buffer compared to LC50 values of ∼ 100-150 μM when the cultures were treated with HD in culture medium. Addition of NaCl to the buffer increased HD toxicity in a salt concentration-dependent manner to values similar to those obtained in culture medium. HD toxicity was dependent on both cationic and anionic species with anionic environment playing a much larger role in determining toxicity. Substitution of NaI for NaCl in the treatment buffers increased HD toxicity by over 1000%. The activity of the sodium hydrogen exchanger (NHE) in recovering from cytosolic acidification in salt-free and in different chloride salts did not correlate with the HD-induced toxicity in these buffers. However, the inhibition by HD of intracellular pH regulation correlated with its toxicity in NaCl, NaI and sucrose buffers. Analytical chemical studies and the toxicity of the iodine mustard derivative ruled out the role of chemical reactions yielding differentially toxic species as being responsible for the differences in HD toxicity observed. This work demonstrates that the early events that HD sets into motion to cause toxicity are dependent on ionic environment, possibly due to intracellular pH deregulation.

  2. Thermodynamics of non-ionic surfactant Triton X-100-cationic surfactants mixtures at the cloud point

    International Nuclear Information System (INIS)

    Highlights: → Non-ionic surfactants are used as emulsifier and solubilizate in such as textile, detergent and cosmetic. → Non-ionic surfactants occur phase separation at temperature as named the cloud point in solution. → Dimeric surfactants have attracted increasing attention due to their superior surface activity. → The positive values of ΔGcp0 indicate that the process proceeds nonspontaneous. - Abstract: This study investigates the effects of gemini and conventional cationic surfactants on the cloud point (CP) of the non-ionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The thermodynamic parameters of these mixtures were calculated at different cationic surfactant concentrations. The gemini surfactants of the alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as 'm-2-m' (m = 10, 12, and 16) and, on the other hand, with -C16 alkyl groups and different spacers containing s carbon atoms, referred to as '16-s-16' (s = 6 and 10) were synthesized, purified and characterized. Additions of the cationic surfactants to the TX-100 solution increased the cloud point temperature of the TX-100 solution. It was accepted that the solubility of non-ionic surfactant containing polyoxyethylene (POE) hydrophilic chain was a maximum at the cloud point so that the thermodynamic parameters were calculated at this temperature. The results showed that the standard Gibbs free energy (ΔGcp0), the enthalpy (ΔHcp0) and the entropy (ΔScp0) of the clouding phenomenon were found positive in all cases. The standard free energy (ΔGcp0) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic surfactants; however, it decreased with increasing surfactant concentration.

  3. Structure and ionic conductivity of ionic liquid embedded PEO- LiCF3SO3 polymer electrolyte

    OpenAIRE

    Karmakar, A.; Ghosh, A.

    2014-01-01

    In this paper we have reported electrical and other physical properties of polyethylene oxide (PEO) - LiCF3SO3 polymer electrolytes embedded with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid. The addition of the ionic liquid to PEO- LiCF3SO3 electrolyte increases the amorphous phase content considerably and decreases the glass transition temperature. The relative amounts of different ionic species present in these electrolytes have been determined. It is observed that th...

  4. Study of an ionic smoke sensor

    International Nuclear Information System (INIS)

    Ionization smoke sensors are among the best smoke sensors; however, the little radioactive source they include is no longer desirable since it makes recycling more complicated. In this paper, we discuss an electrostatic system in which a corona discharge is used to generate the ions needed for smoke detection. We show how the velocity of ions is reduced in our system for a better interaction between smoke and drifting ions. The influence of smoke, temperature and moisture is studied. It is shown that the proposed sensor has good sensitivity compared with conventional ionic and optical smoke sensors. (paper)

  5. INTERACTION OF IONIC LIQUIDS WITH POLYSACCHARIDES

    Directory of Open Access Journals (Sweden)

    Tim Liebert

    2008-05-01

    Full Text Available The use of ionic liquids (ILs in the field of cellulose chemistry opens up a broad variety of new opportunities. Besides the regeneration of the biopolymer to fibers, films, and beads, this new class of cellulose solvents is particularly useful for the homogeneous chemical modification of the polysaccharide. In this review, the potential of ILs as a reaction medium for the homogeneous cellulose functionalization is discussed. It is shown that numerous conversions proceed very efficiently and the ILs may be recycled. But it is also demonstrated that some side reactions have to be considered.

  6. Synthesis of Ionic Colloidal Crystals (ICCs)

    Science.gov (United States)

    Maskaly, Garry R.; Garcia, R. Edwin; Carter, W. Craig; Chiang, Yet-Ming

    2003-03-01

    Binary ionic colloidal crystals (ICCs) have been produced by ordered heterocoagulation of colloidal mixtures of silica (negative surface charge) and polystyrene functionalized with amidine (positive surface charge) suspended in isopropanol. Experimental conditions predicted by the theoretical model discussed in a separate talk have been implemented to obtain heterocoagulation of these particles in the rocksalt structure. To our knowledge, this is the first experimental demonstration of the ICC concept. The importance of various experimental parameters on ICC formation is discussed. Particle dynamics simulations are carried out to provide insight into the kinetics of ICCs. Potential applications are discussed.

  7. Computationally Efficient Prediction of Ionic Liquid Properties

    DEFF Research Database (Denmark)

    Chaban, V. V.; Prezhdo, O. V.

    2014-01-01

    the ability of RTILs to stay liquid at several hundred degrees Celsius and introduce a straightforward and computationally efficient method for predicting RTIL properties at ambient temperature. RTILs do not alter phase behavior at 600-800 K. Therefore, their properties can be smoothly extrapolated...... down to ambient temperatures. We numerically prove the validity of the proposed concept for density and ionic diffusion of four different RTILs. This simple method enhances the computational efficiency of the existing simulation approaches as applied to RTILs by more than an order of magnitude....

  8. The problem of ionic-atomic dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Baldanov, M.N.; Mokhosov, M.V.

    1986-03-01

    This paper shows that in order to determine the ionic radii of the elements, it is sufficient to make use of handbook values for the energy of sublimation (or atomization) and ionization of the substance. In this sense, there is interest in the possibility of estimating the radii for ions in any oxidation state. Some results of the estimates of radii are presented and are in satisfactory agreement with empirical values. For negative ions, instead of the ionization energy the authors use the electron affinity energy.

  9. The problem of ionic-atomic dimensions

    International Nuclear Information System (INIS)

    This paper shows that in order to determine the ionic radii of the elements, it is sufficient to make use of handbook values for the energy of sublimation (or atomization) and ionization of the substance. In this sense, there is interest in the possibility of estimating the radii for ions in any oxidation state. Some results of the estimates of radii are presented and are in satisfactory agreement with empirical values. For negative ions, instead of the ionization energy the authors use the electron affinity energy

  10. Ionically self-assembled monolayers (ISAMs)

    Science.gov (United States)

    Janik, John

    2001-04-01

    Ionically self-assembled monolayers (ISAMs), fabricated by alternate adsorption of cationic and anionic components, yield exceptionally homogeneous thin films with sub-nanometer control of the thickness and relative special location of the component materials. Using organic electrochromic materials such as polyaniline, we report studies of electrochromic responses in ISAM films. Reversible changes in the absorption spectrum are observed with the application of voltages on the order of 1.0 V. Measurements are made using both liquid electrolytes and in all-solid state devices incorporating solid polyelectrolytes such as poly(2-acylamido 2-methyl propane sulfonic acid) (PAMPS).

  11. ZnO-ionic liquid nanostructures

    International Nuclear Information System (INIS)

    The mixture of nanostructures derived from the surface interactions and reactivity of ZnO nanoparticles with the room-temperature ionic liquid (IL1) 1-hexyl, 3-methylimidazolium hexafluorophosphate has been studied. Results are discussed on the basis of transmission electron microscopy (TEM) observations, energy dispersive spectroscopy (EDS) analysis, X-ray diffraction (XRD) patterns and X-ray photoelectron spectroscopy (XPS) determinations. Size and morphology changes in ZnO nanoparticles by surface modification with IL1 are observed. ZnF2 crystalline needles due to reaction with the hexafluorophosphate anion are also formed.

  12. TETRAALKYLPHOSPHONIUM POLYOXOMETALATES AS NOVEL IONIC LIQUIDS.

    Energy Technology Data Exchange (ETDEWEB)

    DIETZ,M.L.; RICKERT, P.G.; ANTONIO, M.R.; FIRESTONE, M.A.; WISHART, J.F.; SZREDER, T.

    2007-11-30

    The pairing of a Lindqvist or Keggin polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation, [R{sub 3}R{prime}P]{sup +}, has been shown to yield an original family of ionic liquids (POM-ILs), among them salts liquid at or near ambient temperature. The physicochemical properties of several such 'inorganic liquids', in particular their thermal properties, suggests the possible application of these compounds as robust, thermally-stable solvents for liquid-liquid extraction. A preliminary evaluation of the potential of POM-ILs in this application is presented.

  13. Design of Separation Processes with Ionic Liquids

    DEFF Research Database (Denmark)

    Peng-noo, Worawit; Kulajanpeng, Kusuma; Gani, Rafiqul;

    2015-01-01

    A systematic methodology for screening and designing of Ionic Liquid (IL)-based separation processes is proposed and demonstrated using several case studies of both aqueous and non-aqueous systems, for instance, ethanol + water, ethanol + hexane, benzene + hexane, and toluene + methylcyclohexane....... The best four ILs of each mixture are [mmim][dmp], [emim][bti], [emim][etso4] and [hmim][tcb], respectively. All of them were used as entrainers in the extractive distillation. A process simulation of each system was carried out and showed a lower both energy requirement and solvent usage as compared...

  14. HENRY'S LAW CALCULATOR

    Science.gov (United States)

    On-Site was developed to provide modelers and model reviewers with prepackaged tools ("calculators") for performing site assessment calculations. The philosophy behind OnSite is that the convenience of the prepackaged calculators helps provide consistency for simple calculations,...

  15. TEX86 temperatures and multi-species foraminiferal Mg/Ca temperatures and ?13C reflect changes in glacial nutrient dynamics and upper water column hydrography of the Eastern Equatorial Pacific

    Science.gov (United States)

    Hertzberg, J.; Schmidt, M. W.; Bianchi, T. S.; Smith, R. K.; Shields, M. R.; Randle, N. J.

    2013-12-01

    to a deepening of the mixed-layer and chemocline during the LGM (Spero et al., 2003), we measured the δ13C of G. ruber and the thermocline dwelling foraminifera Globorotalia menardii and Neogloboquadrina dutertrei. At the Carnegie Ridge site, G. menardii δ13CDIC normalized values display a prominent shift to lower values at the glacial termination, indicating a shoaling of the δ13CDIC chemocline and a decrease in mixed layer depth. However, the situation is less clear on the Cocos Ridge where TEX86H and G. ruber Mg/Ca temperatures display the largest offset at the LGM. We will also present Holocene and LGM Mg/Ca temperatures for G. menardii and N. dutertrei to better constrain GDGT export depth at both locations. This study has important implications not only for the use of the TEX86 paleothermometer in the EEP, but when taken together, the TEX86 temperatures and multi-species Mg/Ca temperatures and δ13C data will provide critical insight into the hydrographic structure and nutrient dynamics of the Holocene-LGM mixed layer and thermocline in the EEP.

  16. Ionic Covalent Organic Frameworks with Spiroborate Linkage.

    Science.gov (United States)

    Du, Ya; Yang, Haishen; Whiteley, Justin Michael; Wan, Shun; Jin, Yinghua; Lee, Se-Hee; Zhang, Wei

    2016-01-01

    A novel type of ionic covalent organic framework (ICOF), which contains sp(3)  hybridized boron anionic centers and tunable countercations, was constructed by formation of spiroborate linkages. These ICOFs exhibit high BET surface areas up to 1259 m(2)  g(-1) and adsorb a significant amount of H2 (up to 3.11 wt %, 77 K, 1 bar) and CH4 (up to 4.62 wt %, 273 K, 1 bar). Importantly, the materials show good thermal stabilities and excellent resistance to hydrolysis, remaining nearly intact when immersed in water or basic solution for two days. The presence of permanently immobilized ion centers in ICOFs enables the transportation of lithium ions with room-temperature lithium-ion conductivity of 3.05×10(-5)  S cm(-1) and an average Li(+) transference number value of 0.80±0.02. Our approach thus provides a convenient route to highly stable COFs with ionic linkages, which can potentially serve as absorbents for alternative energy sources such as H2 , CH4 , and also as solid lithium electrolytes/separators for the next-generation lithium batteries. PMID:26696304

  17. Ionic liquid nanostructure enables alcohol self assembly.

    Science.gov (United States)

    Murphy, Thomas; Hayes, Robert; Imberti, Silvia; Warr, Gregory G; Atkin, Rob

    2016-05-14

    Weakly structured solutions are formed from mixtures of one or more amphiphiles and a polar solvent (usually water), and often contain additional organic components. They contain solvophobic aggregates or association structures with incomplete segregation of components, which leads to a poorly defined interfacial region and significant contact between the solvent and aggregated hydrocarbon groups. The length scales, polydispersity, complexity and ill-defined structures in weakly structured solutions makes them difficult to probe experimentally, and obscures understanding of their formation and stability. In this work we probe the nanostructure of homogenous binary mixtures of the ionic liquid (IL) propylammonium nitrate (PAN) and octanol as a function of composition using neutron diffraction and atomistic empirical potential structure refinement (EPSR) fits. These experiments reveal why octanol forms weakly structured aggregates in PAN but not in water, the mechanism by which PAN stabilises the octanol assemblies, and how the aggregate morphologies evolve with octanol concentration. This new understanding provides insight into the general stabilisation mechanisms and structural features of weakly structured mixtures, and reveals new pathways for identifying molecular or ionic liquids that are likely to facilitate aggregation of non-traditional amphiphiles. PMID:27102801

  18. Magnetic ionic liquids: synthesis and characterization

    International Nuclear Information System (INIS)

    The synthesis of magnetic ionic liquids (MILs) based on the stable dispersions of magnetic nanoparticles (MNPs) of γ-Fe2O3, Fe3O4, and CoFe2O4 in the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf2) is reported. The MNPs were obtained by the coprecipitation method. The surface of the α-Fe2O3, Fe3O4, and CoFe2O4 MNPs with mean sizes (XRD) of 9.3, 12.3, and 11.0 nm, respectively were functionalized by 1-n-butyl-3-(3'-trimethoxypropylsilane)- imidazolium chloride. The non functionalized and functionalized MNPs were further characterized by Raman, FTIR-ATR, and FTNIR spectroscopy and by TGA. The stability of the MILs was assigned to the formation of at least one monolayer of the surface modifier agent that mimics the structure of the BMI.NTf2 IL. (author)

  19. Cellulose multilayer Membranes manufacture with Ionic liquid

    KAUST Repository

    Livazovic, S.

    2015-05-09

    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol-1 with corresponding water permeance of 13.8 Lm−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

  20. Sequencing proteins with transverse ionic transport

    Science.gov (United States)

    Boynton, Paul; di Ventra, Massimiliano

    2015-03-01

    De novo protein sequencing is essential for understanding cellular processes that govern the function of living organisms. By obtaining the order of the amino acids that composes a given protein one can determine both its secondary and tertiary structures through protein structure prediction, which is used to create models for protein aggregation diseases such as Alzheimer's Disease. Mass spectrometry is the current technique of choice for de novo sequencing, but because some amino acids have the same mass the sequence cannot be completely determined in many cases. In this paper we propose a new technique for de novo protein sequencing that involves translocating a polypeptide through a synthetic nanochannel and measuring the ionic current of each amino acid through an intersecting perpendicular nanochannel, similar to that proposed in for DNA sequencing. Indeed, we find that the distribution of ionic currents for each of the 20 proteinogenic amino acids encoded by eukaryotic genes is statistically distinct, showing this technique's potential for de novo protein sequencing.

  1. NMR in solid ionic and nanoionics

    International Nuclear Information System (INIS)

    Full text: Nuclear Magnetic Resonance (NMR) is a spectroscopic technique which employs magnetic nuclei to study, among others, the dynamics of condensed matter at the atomic level. Thus, NMR has been and still is a successful instrument in the research field of solid electrolytes also known as solid ionics. This paper presents the typical NMR experiments performed in solid ionics together with some examples from nanoionics. The experiments to be discussed comprise: (i) measurements of the diffusion coefficient employing the pulsed-field gradient and the static fringe-field method; (ii) the experimentally related NMR imaging; (iii) double resonance experiments like spin-echo double resonance (SEDOR) and two-dimensional Fourier transform NMR (2D-FT NMR); (iv) various types of nuclear relaxation, in particular spin-lattice relaxation. The NMR techniques yield information on topics like the following: type and number of mobile atoms and defects, diffusion pathways (e.g. dimensionality restrictions), atomic jump frequencies, activation energy and activation volume of these movements, diffusion coefficient with activation energy and prefactor, correlation effects in atomic movements, space correlation factor, cooperative phenomena, symmetry of atomic sites, behavior at phase transitions. These applications will be illustrated by giving examples from crystals, glasses, and polymers. (author)

  2. Ionic migration in soils and clays

    International Nuclear Information System (INIS)

    Migration of ions in soil to plant roots takes place either by the viscous movement of the soil solution through the pore space, or by ionic diffusion. As long as there is drainage viscous flow is possible, but when once the drainage stops ionic diffusion alone migrates the ions. The amount of the nutrient ion that diffuses at a given temperature in a soil depends upon the soil structure and the moisture condition. In free liquids, or in straight uniform channels, the diffusing ions are not obstructed in the course of their migration along the direction of measurement. In such cases the whole fractional area of the cross-section will be effective. But in a bed of soil where the channels bend round corners, forming twists and constrictions, the quantity of the ion diffused falls short of the expected value and the decrease in the ion diffused in such cases should be attributed to the twists and constrictions. The effective fractional areas obtained under different conditions of compaction give a measure of the effect of twists and constrictions on the migration of ions in each case

  3. Solvent extraction of aromatic sulfur compounds from n-heptane using the 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid

    International Nuclear Information System (INIS)

    Highlights: • LLE data for (EMIMTCM + thiophene/benzothiophene + n-heptane) were determined. • High S and β for the extraction of thiophene/benzothiophene from n-heptane was found. • Results of S and β were compared with available literature. • The NRTL model satisfactorily correlates the LLE data. -- Abstract: The ionic liquid 1-ethyl-3-methylimidazolium tricyanomethanide ([EMIM][TCM]) has been tested as a solvent for the separation of sulfur compounds from aliphatic hydrocarbon. Liquid–liquid phase equilibrium data have been determined for ternary systems containing the ionic liquid, thiophene or benzothiophene and n-heptane. The influence of temperature on the separation of thiophene from n-heptane was determined. High solubility of sulfur compounds and practical immiscibility of aliphatic hydrocarbon in ionic liquid have been found. The values of selectivity and solute distribution ratios have been calculated for all systems and compared with literature data for other 1-ethyl-3-methylimidazolium-based ionic liquids. High values of selectivity were obtained. The experimental data were correlated using the NRTL equation, and the binary interaction parameters have been reported. The phase equilibria diagrams for the ternary mixtures including the experimental and calculated tie-lines have been presented

  4. Thermophysical properties of ionic liquid {1-butyl-3-methylimidazolium bromide [bmim][Br] in alkoxyalkanols + water} mixtures at different temperatures

    International Nuclear Information System (INIS)

    Highlights: ► Densities and speeds of sound of alkoxyalkanols in [bmim][Br]. ► Synthesis of room temperature ionic liquid [bmim][Br]. ► Partial molar volumes and compressibility of transfer. ► Apparent molar expansivities and the Hepler’s constant were calculated. ► Solute–solute and solute–solvent interactions and the structural changes of the solutes. - Abstract: The interactions of alkoxyalkanols with the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim][Br] as a function of temperature were investigated by combination of volumetric and acoustic methods. The density, ρ, and speed of sound, u, of ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and triethylene glycol monomethyl ether (0.00–1.01 mol·kg−1) in aqueous 1-butyl-3-methylimidazolium bromide solutions ranging from pure water to 0.29 mass% of ionic liquid have been measured at T = (288.15, 298.15 and 308.15) K and atmospheric pressure. The apparent molar volume (Vφ) and adiabatic compressibility (Kφ,S) of alkoxyalkanols in aqueous ionic liquid solution were determined at the measured temperatures. The partial molar volume (Vφ0) and partial molar adiabatic compressibility (Kφ0) of alkoxyalkanols at infinite dilution were evaluated. Transfer volumes (ΔVφ0) and transfer adiabatic compressibility (ΔKφ0) at infinite dilution from water to aqueous ionic liquid solution were also calculated. The temperature dependence of the apparent molar volume was used to calculate apparent molar expansivity (φE0) and the Hepler’s constant values, (∂2Vφ0/∂T2). The results were explained on the basis of competing patterns of interactions of co-solvent and the solute.

  5. Determination of mendelevium (1+) ionic radius and MdCl solubility on the basis of its isomorphous cocrystallization with NaCl and KCl

    International Nuclear Information System (INIS)

    On the basis of previously obtained exlperimental data on coefficients of cocrystallization of microamounts of MdCl with NaCl and KCl in water-ethanol solutions the calculation of ionic radius of mendelevium (1+) are made. It turned out that for coordination number 6 value Rsub(Mdsup(+))=0.117 nm, which agrees with theoretically calculated value. Solubility and product of MdCl activity in water-ethanol solutions of different compositions at 25 deg are calculated

  6. Thermal annealing and ionic abrasion in ZnTe

    International Nuclear Information System (INIS)

    Thermal annealing of the ZnTe crystal is studied first in order to obtain information on the aspect of the penetration profile. Ionic abrasion is then investigated to find out whether it produces the same effects as ionic implantation, especially for luminescence

  7. Polarity of the interface in ionic liquid in oil microemulsions.

    Science.gov (United States)

    Andújar-Matalobos, María; García-Río, Luis; López-García, Susana; Rodríguez-Dafonte, Pedro

    2011-11-01

    Ionic liquid based microemulsions were characterized by absorption solvatochromic shifts, (1)H NMR and kinetic measurements in order to investigate the properties of the ionic liquid within the restricted geometry provided by microemulsions and the interactions of the ionic liquid with the interface. Experimental results show a significant difference between the interfaces of normal water and the new ionic liquid microemulsions. Absorption solvatochromic shift experiments and kinetic studies on the aminolysis of 4-nitrophenyl laurate by n-decylamine show that the polarity at the interface of the ionic liquid in oil microemulsions (IL/O) is higher than at the interface of water in oil microemulsions (W/O) despite the fact that the polarity of [bmim][BF(4)(-)] is lower than the polarity of water. (1)H NMR experiments showed that an increase in the ionic liquid content of the microemulsion led to an increase in the interaction between [bmim][BF(4)(-)] and TX-100. The reason for the higher polarity of the microemulsions with the ionic liquid can be explained in terms of the incorporation of higher levels of the ionic liquid at the interface of the microemulsions, as compared to water in the traditional systems. PMID:21820124

  8. Absorption and oxidation of no in ionic liquids

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention concerns the absorption and in situ oxidation of nitric oxide (NO) in the presence of water and oxygen in ionic liquid compositions at ambient temperature.......The present invention concerns the absorption and in situ oxidation of nitric oxide (NO) in the presence of water and oxygen in ionic liquid compositions at ambient temperature....

  9. Ionic Liquids and Green Chemistry: A Lab Experiment

    Science.gov (United States)

    Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

    2010-01-01

    Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of…

  10. An Ionic Liquid Solution of Chitosan as Organocatalyst

    Directory of Open Access Journals (Sweden)

    René Wilhelm

    2013-11-01

    Full Text Available Chitosan, which is derived from the biopolymer chitin, can be readily dissolved in different ionic liquids. The resulting homogeneous solutions were applied in an asymmetric Aldol reaction. Depending on the type of ionic liquid used, high asymmetric inductions were found. The influence of different additives was also studied. The best results were obtained in [BMIM][Br] without an additive.

  11. Transport and Molecular Organization in Ionic Liquids of Various Structures

    Czech Academy of Sciences Publication Activity Database

    Andresová, Adéla; Bendová, Magdalena; Storch, Jan; Traika, M.; Wagner, Zdeněk; Husson, P.

    Eindhoven : -, 2014, O65. ISBN N. [European Symposium on Applied Thermodynamics (ESAT 2014) "Experiments meet Theory and Simulation" /27./. Eindhoven (NL), 06.07.2014-09.07.2014] Institutional support: RVO:67985858 Keywords : ionicity * transport * ionic liquids Subject RIV: CF - Physical ; Theoretical Chemistry

  12. Dielectric electroactive polymers comprising an ionic supramolecular structure

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to an ionic interpenetrating polymer network comprising at least one elastomer and an ionic supramolecular structure comprising the reaction product of at least two chemical compounds wherein each of said compounds has at least two functional groups and wherein said...

  13. Synthesis and Characterization of Dual Acidic Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    Xiao Hua WANG; Guo Hong TAO; Zi Yan ZHANG; Yuan KOU

    2005-01-01

    Novel ionic liquids with dual acidity, of which the cation contains Bronsted acidity and anions contain Lewis acidity were synthesized. These ionic liquids obtained were identified by NMR,FT-IR, SDT and FAB-MS. Their acidities were determined by pyridine probe on IR spectrography.

  14. Method for enhancing the thermal stability of ionic compounds

    OpenAIRE

    Riisager, Anders; Fehrmann, Rasmus; Robin, Roger; Gabriela, Gurau

    2013-01-01

    This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA.

  15. Absorption and oxidation of nitrogen oxide in ionic liquids

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Thomassen, Peter Langelund; Riisager, Anders;

    2016-01-01

    A new strategy for capturing nitrogen oxide, NO, from the gas phase is presented. Dilute NO gas is removed from the gas phase by ionic liquids under ambient conditions. The nitrate anion of the ionic liquid catalyzes the oxidation of NO to nitric acid by atmospheric oxygen in the presence of water...

  16. The Origin of the Ionic-Radius Ratio Rules

    Science.gov (United States)

    Jensen, William B.

    2010-01-01

    In response to a reader query, this article traces the origins of the ionic-radius ratio rules and their incorrect attribution to Linus Pauling in the chemical literature and to Victor Goldschmidt in the geochemical literature. In actual fact, the ionic-radius ratio rules were first proposed within the context of the coordination chemistry…

  17. Viscoelasticity and microstructure of non-ionic microemulsions

    NARCIS (Netherlands)

    Eshuis, A.; Mellema, J.

    1984-01-01

    Non-ionic microemulsions were investigated by viscoelastic measurements in the kHz region. We found that in some parts of the phase diagram our systems consisted of a dispersion of spherical oil doplets, stabilized by a non-ionic surfactant, in a continuous phase of almost pure water. Because of the

  18. Protic Cationic Oligomeric Ionic Liquids of the Urethane Type

    DEFF Research Database (Denmark)

    Shevchenko, V. V.; Stryutsky, A. V.; Klymenko, N. S.; Gumennaya, M. A.; Fomenko, A. A.; Trachevsky, V. V.; Davydenko, V. V.; Bliznyuk, V. N.; Dorokhin, Andriy

    2014-01-01

    Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine...... derivatives of imidazole, pyridine, and 3-methylpyridine and neutralization of heterocycles with ethanesulfonic acid and p-toluenesulfonic acid. The structures and properties of the synthesized oligomeric ionic liquids substantially depend on the structures of the ionic groups. They are amorphous at room...... temperature, but ethanesulfonate imidazolium and pyridinium oligomeric ionic liquids form a low melting crystalline phase. The proton conductivities of the oligomeric ionic liquids are determined by the type of cation in the temperature range 80-120 degrees C under anhydrous conditions and vary within five...

  19. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids.

    Science.gov (United States)

    Fadeeva, Tatiana A; Husson, Pascale; DeVine, Jessalyn A; Costa Gomes, Margarida F; Greenbaum, Steven G; Castner, Edward W

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies. PMID:26277141

  20. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Fadeeva, Tatiana A.; DeVine, Jessalyn A.; Castner, Edward W., E-mail: ed.castner@rutgers.edu [Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 (United States); Husson, Pascale [CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, BP 80026, F-63171 Aubière (France); Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Costa Gomes, Margarida F. [CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, BP 80026, F-63171 Aubière (France); Greenbaum, Steven G. [Department of Physics and Astronomy, Hunter College, CUNY, New York, New York 10065 (United States)

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies.

  1. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    International Nuclear Information System (INIS)

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies

  2. Solubility of gases in 1-alkyl-3methylimidazolium alkyl sulfate ionic liquids: Experimental determination and modeling

    International Nuclear Information System (INIS)

    Highlights: ► The solubility of CO2, CH4 and C2H6 in [emim][EtSO4] is measured with a magnetic suspension balance. ► New data and literature results have been modeled with a Group Contribution equation of state. ► A specific group definition is required to model data of ionic liquids with a [MeSO4] anion. ► Deviations between model and experiments are lower than 10% in most cases. ► Deviations of 34% are observed in the case of the solubility of ethane in the ionic liquid. -- Abstract: The solubility of different gases (carbon dioxide, methane, ethane, carbon monoxide and hydrogen) in ionic liquids with an alkyl sulfate anion has been modeled with the Group Contribution equation of state developed by Skjold-Jørgensen. New gas solubility measurements have been carried out with a high pressure magnetic suspension balance in order to cover pressure and temperature ranges not considered in previous studies and to obtain more experimental information for the correlation of parameters of the equation of state. New solubility measurements include the solubility of carbon dioxide in 1-ethyl 3-methyl imidazolium ethyl sulfate [emim][EtSO4] at temperatures of 298 K and 348 K and pressures ranging from 0.3 MPa to 6.5 MPa, the solubility of methane in [emim][EtSO4] at a temperature of 293 K and pressures ranging from 0.2 MPa to 10.2 MPa, and the solubility of ethane in [emim][EtSO4] at temperatures of 323 K and 350 K and pressures ranging from 0.2 MPa to 4 MPa. Results show that the Group Contribution equation of state can be used to describe the solubility of gases in alkyl sulfate ionic liquids as well as infinite dilution coefficients of alkanes in the ionic liquids, with average deviations between experiments and calculations ranging from 1% to 10% in the case of mixtures with CO2, CO, CH4 and H2 with the alkyl sulfate ionic liquids to up to 34% in the case of the solubility of ethane in [emim][EtSO4

  3. Ionic Diffusion in High Temperature Uranium Dioxide

    International Nuclear Information System (INIS)

    Uranium dioxide nuclear fuels are being subjected to increasingly higher central temperatures and larger thermal gradients which contribute significantly to changes in the physical properties, to the distribution of fission products, to the oxide composition and specifically to the mechanism of material transport. The purpose of this paper is to discuss recent high temperature property measurements of UO2, made both in- and out-of-reactor, that pertain to atomic movement and to suggest further areas for high temperature thermodynamic research. High temperature measurements of electrical conductivity, thermo-electric EMF, solid state fission-fragment migration and studies of phase equilibria in the oxygen-uranium system suggest that ionic diffusion in an electrical potential gradient contributes significantly to the movement of fission products and oxygen. The electrical property measurements of uranium dioxide show evidence of a high Seebeck coefficient, a p-type to n-type conductivity change and an ionic character in high temperatures. These data are being confirmed by in-reactor electrical property measurements. The distribution of solid fission fragments observed in irradiated UO2 fuel elements cannot be explained solely in terms of diffusion in a thermal or concentration gradient. Solid fission fragments were shown to diffuse in an electric potential gradient at high temperatures in the absence of any thermal gradient.. The thermal EMF produced by the thermal gradient in a fuel element during irradiation is thought to contribute to the migration of fission fragments by ionic diffusion. In-reactor tests of this hypothesis are under way. The measurements and interpretation of high temperature property data are complicated by changes in stoichiometry. Phase equilibria and melting point studies in the temperaturè range 1600 -3000°C show a wide range of single phase UO2-x existing above 1600°C. The melting point of UO2-x reaches a maximum at approximately UO1

  4. Electron impact single ionization of light ionic targets with charge q > 2

    International Nuclear Information System (INIS)

    The electron impact single ionization cross-section of light ionic targets with multiple charges greater than 2 is evaluated employing two distinct modifications of the binary-encounter dipole (BED) model, the intermediate BEDTG and the modified BED (MBED) models. BEDTG incorporates the ionic correction due to Thomas and Garcia, whereas MBED embodies modification of the Burgess denominator along with the ionic correction. The differential continuum oscillator strengths are obtained adopting the analytic fits to available photo-ionization cross-sections, calculated quantum mechanically. To assess the reliability of these proposed modifications, a few simple targets, e.g., C3+, N4+, O4+, O5+, Ne6+ and Ne7+ with known reliable theoretical results, are considered. Although the present MBED model seems to underestimate systematically the experimental data above 10 keV, it explains the data in the threshold and peak regions reasonably well with its predictions close to those from the Coulomb-Born approximation, convergent-close-coupling, distorted wave Born approximation with R-matrix, time-dependent and R-matrix pseudo-state methods

  5. Effect of high ionic strength on the extraction of uranium(VI ions

    Directory of Open Access Journals (Sweden)

    M.K. Nazal

    2014-01-01

    Full Text Available Preparation and characterization of didodecylphosphoric acid (HDDPA as an extractant in toluene was carried. Mass spectroscopy showed that the monomer peak at 457.4 amu [M–Na+] is double that of the dimer at 891.9 amu [M–M–Na+] and the monomer molecules concentration dominate the dimer molecules in toluene. HDDPA was used as an extractant for the extraction of U(VI ion from perchlorate and nitrate media that have ionic strength (1.00, 3.00, 5.00, 7.00 M. The effect of HDDPA concentration, pcH, ionic strength of supporting electrolytes, and temperature in the range 15–45 °C on the extraction process have been studied. The stoichiometry of the extraction of U(VI ion, the free energy change (ΔG, the enthalpy change (ΔH, the entropy change (ΔS, and Kex at different ionic strength have been calculated. The formula of the complexes, which were formed has been established to be UO2(X(R2(HR2 at pcH equal 2.00 and UO2(X(R2(HR2 and UO2(X(R2 at pcH = 1.00, where (X isClO4- orNO3- and (HR2 is didodecylphosphoric acid monomer, (R2 is the deprotonated didodecylphosphoric acid, where R is the dodecyl group.

  6. Metal-Oxygen Bond Ionicity as an Efficient Descriptor for Doped NiOOH Photocatalytic Activity.

    Science.gov (United States)

    Zaffran, Jeremie; Toroker, Maytal Caspary

    2016-06-01

    The computational design of solid catalysts has become a very "hot" field during the last decades, especially with the recent increase in computational tool performance. However, theoretical techniques are still very time demanding because they require the consideration of many adsorption configurations of the reaction intermediates on the surface. Herein, we propose to use the metal-oxygen (M-O) bond ionicity as a descriptor for the photocatalytic activity of one of the best catalysts for the oxygen evolution reaction (OER). Ionicity is a bulk property and thus carries the advantage of being easily obtainable from a simple Bader charge analysis by using density functional theory (DFT). We will show that this criterion can be used successfully to design efficient dopants for NiOOH material. This catalyst is known to exhibit interesting photoelectrochemical properties for OER if it is doped with specific transition metals. Finally, we demonstrate that other electronic properties that relate to bulk calculation, such as oxidation states and density of states, are not alone sufficient to explain the photocatalytic activity of the material. Thus, M-O bond ionicity attracts significant interest compared with other bulk observables obtained by using DFT computations. PMID:26945687

  7. Association of ionic liquids with cationic dyes in aqueous solution: A thermodynamic study

    International Nuclear Information System (INIS)

    Highlights: ► Precipitate was formed between cationic dye and ionic liquid in aqueous solution. ► Precipitates are 1:1 formed by cation of the dyes and anion of the ionic liquids. ► Association constants decrease with increasing temperature. ► The associates can be used as active materials of ion-selective electrode. - Abstract: In this paper, the interactions between cationic dyes and the ionic liquids (ILs) have been studied by 31P nuclear magnetic resonance (NMR), UV–Vis spectroscopy and conductometric measurements at different temperatures. It was shown that a decrease in the measured specific conductance of the (dye + IL) mixtures was caused by the formation of non-conducting or less conducting (dye + IL) associates. The associates were formed by 1:1 ratio of cation of the cationic dyes and anion of the ILs by using the 31P NMR and UV–Vis spectroscopy methods. The association constants were calculated by theoretical model based on the deviation from linear behavior, and the association constants were as high as 106 (L · mol−1)2. Thermodynamic results imply that the formation process of association was exothermic nature. It is expected that the associates reported here would have promising application as active materials for the preparation of ion-selective electrode used in the determination of ILs concentrations.

  8. Understanding the hydrogen bonds in ionic liquids and their roles in properties and reactions.

    Science.gov (United States)

    Dong, Kun; Zhang, Suojiang; Wang, Jianji

    2016-05-21

    Ionic liquids (ILs) have many potential applications in the chemical industry. In order to understand ILs, their molecular details have been extensively investigated. Intuitively, electrostatic forces are solely important in ILs. However, experiments and calculations have provided strong evidence for the existence of H-bonds in ILs and their roles in the properties and applications of ILs. As a structure-directing force, H-bonds are responsible for ionic pairing, stacking and self-assembling. Their geometric structure, interaction energy and electronic configuration in the ion-pairs of imidazolium-based ILs and protic ionic liquids (PILs) show a great number of differences compared to conventional H-bonds. In particular, their cooperation with electrostatic, dispersion and π interactions embodies the physical nature of H-bonds in ILs, which anomalously influences their properties, leading to a decrease in their melting points and viscosities and thus fluidizing them. Using ILs as catalysts and solvents, many reactions can be activated by the presence of H-bonds, which reduce the reaction barriers and stabilize the transition states. In the dissolution of lignocellulosic biomass by ILs, H-bonds exhibit a most important role in disrupting the H-bonding network of cellulose and controlling microscopic ordering into domains. In this article, a critical review is presented regarding the structural features of H-bonds in ILs and PILs, the correlation between H-bonds and the properties of ILs, and the roles of H-bonds in typical reactions. PMID:27042709

  9. Comparison of bioconcentration of ionic silver and silver nanoparticles in zebrafish eleutheroembryos

    International Nuclear Information System (INIS)

    The production of silver nanoparticles has reached nowadays high levels. Bioconcentration studies, information on persistence and toxicity are fundamental to assess their global risk and thus necessary to establish legislations regarding their use. Previous studies on silver nanoparticle toxicity have determined a clear correlation between their chemical stability and toxicity. In this work, experimental conditions able to assure silver nanoparticles stability have been optimized. Then, zebrafish (Danio rerio) eleutheroembryos were exposed to ionic silver and to Ag NPs for comparison purposes. A protocol alternative to the OECD 305 technical guideline was used. To determine silver concentration in both the eleutheroembryos and the exposure media, an analytical method consisting in ultrasound assisted extraction, followed by inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry, was developed. Then, bioconcentration factors were calculated. The results revealed that ionic silver was more accumulative for zebrafish eleutheroembryos than nanoparticles at the levels tested. - Highlights: • Silver nanoparticles stability study in aqueous media. • Evidence of the high divergence in the bioaccumulation studies already published. • Possible alternative to the Bioconcentration Test OECD 305. - Different patterns on accumulation by zebrafish eleutheroembryos of ionic silver and silver nanoparticles have been observed following OECD 305 technical guidelines

  10. Free volume investigation of imidazolium ionic liquids from positron lifetime spectroscopy

    CERN Document Server

    Yu, Yang; Krause-Rehberg, Reinhard

    2014-01-01

    In this work, relationships between the free volume and various fundamental physical properties (density, surface tension and transport properties) of ionic liquids were investigated. Two imidazolium ionic liquids 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluoro phosphate ([C4MIM][FAP]) and 1-butyl-3-methylimidazolium bis[bis(pentafluoroethyl)phosphinyl]imide ([C4MIM][FPI]) were measured by positron annihilation lifetime spectroscopy (PALS). Changes of the ortho-positronium lifetime (o-Ps) with different states (amorphous and crystalline) were depicted as completely as possible. The mean local free (hole) volume was calculated from the o-Ps lifetime in amorphous state for the samples. Comparison between and specific volume obtained from the temperature dependent mass density gave the specific hole densities Nf and the occupied volumes Vocc. Thermal expansion of hole volume was compared with molecular volume VM of [C4MIM][FAP] and [C4MIM][FPI] as well as five other ionic liquids from our previous ...

  11. Scaling properties of fracture surfaces on glass strengthened by ionic exchange

    International Nuclear Information System (INIS)

    In this work the results of the statistical topometric analysis of fracture surfaces of soda-lime-silica glass with and without ionic exchange treatment are reported. In this case, the mechanism of substitution is K+-Na+. atomic force microscopy (AFM) was employed to record the topometric data from the fracture surface. The roughness exponent (ζ) and the correlation length (ξ) were calculated by the variable bandwidth method. The analysis for both glasses (subjected and non-subjected to ionic exchange) for ζ shows a value ∼0.8, this value agrees well with that reported in the literature for rapid crack propagation in a variety of materials. The correlation length shows different values for each condition. These results, along with those of microhardness indentations suggest that the self-affine correlation length is influenced by the complex interactions of the stress field of microcracks with that resulting from the collective behavior of the point defects introduced by the strengthening mechanism of ionic exchange

  12. Thermodynamic and spectroscopic studies on binary mixtures of imidazolium ionic liquids in ethylene glycol

    International Nuclear Information System (INIS)

    Highlights: → Macroscopic and molecular level interactions of imidazolium ionic liquids in ethylene glycol have been determined. → VmE is positive over the whole composition range for all the investigated mixtures. → Multiple hydrogen bonding interactions are prevailing between unlike components in mixtures of varying strengths. → Microscopic level interactions are not reflected in the mixing macroscopic behaviour. - Abstract: The thermodynamic behaviour of imidazolium based ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride [C4mim][Cl]; 1-octyl-3-methylimidazolium chloride [C8mim][Cl], and 1-butyl-3-methylimidazolium methylsulfate [C4mim][C1OSO3] in ethylene glycol [HOCH2CH2OH] (EG) have been investigated over the whole composition range at T = (298.15 to 318.15) K to probe the interactions in bulk. For the purpose, volumetric properties such as excess molar volume, VmE, apparent molar volume, Vφ,i, and its limiting values at infinite dilution, Vφ,i∞, have been calculated from the experimental density measurements. The molecular scale interactions between ionic liquids and EG have been investigated through Fourier transform infrared (FTIR) and 1H NMR spectroscopy. The shift in the vibrational frequency for C-H stretch of aromatic ring protons of ILs and O-H stretch of EG molecules has been analysed. The NMR chemical shifts for various protons of RTILS or EG molecules and their deviations show multiple hydrogen bonding interactions of varying strengths between RTILs and EG in their binary mixtures.

  13. Structure and osmotic pressure of ionic microgel dispersions

    Science.gov (United States)

    Hedrick, Mary M.; Chung, Jun Kyung; Denton, Alan R.

    2015-01-01

    We investigate structural and thermodynamic properties of aqueous dispersions of ionic microgels—soft colloidal gel particles that exhibit unusual phase behavior. Starting from a coarse-grained model of microgel macroions as charged spheres that are permeable to microions, we perform simulations and theoretical calculations using two complementary implementations of Poisson-Boltzmann (PB) theory. Within a one-component model, based on a linear-screening approximation for effective electrostatic pair interactions, we perform molecular dynamics simulations to compute macroion-macroion radial distribution functions, static structure factors, and macroion contributions to the osmotic pressure. For the same model, using a variational approximation for the free energy, we compute both macroion and microion contributions to the osmotic pressure. Within a spherical cell model, which neglects macroion correlations, we solve the nonlinear PB equation to compute microion distributions and osmotic pressures. By comparing the one-component and cell model implementations of PB theory, we demonstrate that the linear-screening approximation is valid for moderately charged microgels. By further comparing cell model predictions with simulation data for osmotic pressure, we chart the cell model's limits in predicting osmotic pressures of salty dispersions.

  14. Structure and osmotic pressure of ionic microgel dispersions

    International Nuclear Information System (INIS)

    We investigate structural and thermodynamic properties of aqueous dispersions of ionic microgels—soft colloidal gel particles that exhibit unusual phase behavior. Starting from a coarse-grained model of microgel macroions as charged spheres that are permeable to microions, we perform simulations and theoretical calculations using two complementary implementations of Poisson-Boltzmann (PB) theory. Within a one-component model, based on a linear-screening approximation for effective electrostatic pair interactions, we perform molecular dynamics simulations to compute macroion-macroion radial distribution functions, static structure factors, and macroion contributions to the osmotic pressure. For the same model, using a variational approximation for the free energy, we compute both macroion and microion contributions to the osmotic pressure. Within a spherical cell model, which neglects macroion correlations, we solve the nonlinear PB equation to compute microion distributions and osmotic pressures. By comparing the one-component and cell model implementations of PB theory, we demonstrate that the linear-screening approximation is valid for moderately charged microgels. By further comparing cell model predictions with simulation data for osmotic pressure, we chart the cell model’s limits in predicting osmotic pressures of salty dispersions

  15. Structure and osmotic pressure of ionic microgel dispersions

    Energy Technology Data Exchange (ETDEWEB)

    Hedrick, Mary M. [Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 (United States); Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108-6050 (United States); Chung, Jun Kyung; Denton, Alan R., E-mail: alan.denton@ndsu.edu [Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 (United States)

    2015-01-21

    We investigate structural and thermodynamic properties of aqueous dispersions of ionic microgels—soft colloidal gel particles that exhibit unusual phase behavior. Starting from a coarse-grained model of microgel macroions as charged spheres that are permeable to microions, we perform simulations and theoretical calculations using two complementary implementations of Poisson-Boltzmann (PB) theory. Within a one-component model, based on a linear-screening approximation for effective electrostatic pair interactions, we perform molecular dynamics simulations to compute macroion-macroion radial distribution functions, static structure factors, and macroion contributions to the osmotic pressure. For the same model, using a variational approximation for the free energy, we compute both macroion and microion contributions to the osmotic pressure. Within a spherical cell model, which neglects macroion correlations, we solve the nonlinear PB equation to compute microion distributions and osmotic pressures. By comparing the one-component and cell model implementations of PB theory, we demonstrate that the linear-screening approximation is valid for moderately charged microgels. By further comparing cell model predictions with simulation data for osmotic pressure, we chart the cell model’s limits in predicting osmotic pressures of salty dispersions.

  16. Fabrication, modeling and optimization of an ionic polymer gel actuator

    International Nuclear Information System (INIS)

    The modeling of the electro-active behavior of ionic polymer gel is studied and the optimum conditions that maximize the deflection of the gel are investigated. The bending deformation of polymer gel under an electric field is formulated by using chemo-electro-mechanical parameters. In the modeling, swelling and shrinking phenomena due to the differences in ion concentration at the boundary between the gel and solution are considered prior to the application of an electric field, and then bending actuation is applied. As the driving force of swelling, shrinking and bending deformation, differential osmotic pressure at the boundary of the gel and solution is considered. From this behavior, the strain or deflection of the gel is calculated. To find the optimum design parameter settings (electric voltage, thickness of gel, concentration of polyion in the gel, ion concentration in the solution, and degree of cross-linking in the gel) for bending deformation, a nonlinear constrained optimization model is formulated. In the optimization model, a bending deflection equation of the gel is used as an objective function, and a range of decision variables and their relationships are used as constraint equations. Also, actuation experiments are conducted using poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) gel and the optimum conditions predicted by the proposed model have been verified by the experiments

  17. Solubilities of isobutane and cyclopropane in ionic liquids

    International Nuclear Information System (INIS)

    Graphical abstract: Henry’s constants for isobutane and cyclopropane in [HMIM][Tf2N] and [P(14)666][TMPP]. - Highlights: • Solubilities of isobutane and cyclopropane in two ionic liquids were reported. • Solubilities were measured from T = (302 to 344) K and from (0.03 to 1.16) MPa. • The effects of temperature and pressure on the solubilities were investigated. • Solubilities of hydrocarbons in [HMIM][Tf2N] and [P(14)666][TMPP] were compared. • A modified Krichevsky–Kasarnovsky equation was used to model experimental data. - Abstract: In this work, we presented the solubilities of isobutane and cyclopropane in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][Tf2N]) and trihexyl tetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate ([P(14)666][TMPP]) from T = (302 to 344) K up to 1.16 MPa. Henry’s constants for isobutane and cyclopropane in [HMIM][Tf2N] and [P(14)666][TMPP] were calculated from experimental results. Solubilities of isobutane and cyclopropane in [HMIM][Tf2N] are apparently smaller than those in [P(14)666][TMPP]. The effects of temperature, pressure and the number of carbon atoms in the hydrocarbons on the solubility were investigated in detail. A modified Krichevsky–Kasarnovsky equation was successfully applied to correlate the experimental results. The mean absolute relative deviations and the maximum absolute relative deviations are less than (2.4 and 4.6)%, respectively

  18. Distributed polarizability models for imidazolium-based ionic liquids.

    Science.gov (United States)

    Millot, Claude; Chaumont, Alain; Engler, Etienne; Wipff, Georges

    2014-09-25

    Quantum chemical calculations are used to derive distributed polarizability models sufficiently accurate and compact to be used in classical molecular dynamics simulations of imidazolium-based room temperature ionic liquids. Two distributed polarizability models are fitted to reproduce the induction energy of three imidazolium cations (1,3-dimethyl-, 1-ethyl-3-methyl-, and 1-butyl-3-methylimidazolium) and four anions (tetrafluoroborate, hexafluorophosphate, nitrate, and thiocyanate) polarized by a point charge located successively on a grid of surrounding points. The first model includes charge-flow polarizabilities between first-neighbor atoms and isotropic dipolar polarizability on all atoms (except H), while the second model includes anisotropic dipolar polarizabilities on all atoms (except H). For the imidazolium cations, particular attention is given to the transferability of the distributed polarizability sets. The molecular polarizability and its anisotropy rebuilt by the distributed models are found to be in good agreement with the exact ab initio values for the three cations and 23 additional conformers of 1-ethyl-3-methyl-, 1-butyl-3-methyl-, 1-pentyl-3-methyl-, and 1-hexyl-3-methylimidazolium cations. PMID:25133873

  19. Extraction desulfurization process of fuels with ionic liquids

    International Nuclear Information System (INIS)

    Highlights: • Extraction of thiophene and benzothiophene from heptane. • The ternary (liquid + liquid) equilibria using ILs. • High selectivity and solute distribution ratio for the extraction of sulfur compounds form alkanes. • [BMPYR][TCM] was proposed as entrainer for the separation process. - Abstract: In this work, we studied the applicability of three ionic liquids (ILs) in the extraction of thiophene, or benzothiophene from heptane at T = 308.15 K and ambient pressure. Experimental data for (liquid + liquid) phase equilibrium (LLE) were obtained for five ternary systems. The 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMPYR][CF3SO3], 1-butyl-1-methylpyrrolidinium tricyanomethanide, [BMPYR][TCM] and 1-hexyl-3-methylimidazolium tetracyanoborate, [HMIM][TCB] were used for the desulfurization process. The [BMPYR][CF3SO3] showed much better selectivity than [HMIM][TCB] in the extraction of thiophene from heptane and all of them showed excellent results in terms of benzothiophene selectivity and distribution ratio compared to what is currently published for different ILs. Chromatography analysis showed that IL was not present in the heptane layer. This eliminates the process of the separation of the solvent from the raffinate layer. The data obtained have been correlated with the non-random two liquid NRTL model. The experimental tie-lines and the phase composition in mole fraction in the ternary systems were calculated with an average root mean square deviation (RMSD) of 0.005

  20. What Can we learn from Raman spectroscopy and model calculations on room temperature ionic liquids?

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2006-01-01

    because the laser light easily passes through the glassy ampoule wall. The method is of course equally valuable for non-hygroscopic substances and mixtures and “green liquids”. Raman spectra - though characteristic for most compounds - do not give direct chemical evidence (species formulae, quantities...

  1. Ionic composition of the earth's radiation belts

    Science.gov (United States)

    Spjeldvik, W. N.

    1983-01-01

    Several different ion species have been positively identified in the earth's radiation belts. Besides protons, there are substantial fluxes of helium, carbon and oxygen ions, and there are measurable quantities of even heavier ions. European, American and Soviet space experimenters have reported ion composition measurements over wide ranges of energies: at tens of keV (ring-current energies) and below, and at hundreds of keV and above. There is still a gap in the energy coverage from several tens to several hundreds of keV where little observational data are available. In this review emphasis is placed on the radiation belt ionic structure above 100 keV. Both quiet time conditions and geomagnetic storm periods are considered, and comparison of the available space observations is made with theoretical analysis of geomagnetically trapped ion spatial, energy and charge state distributions.

  2. Polarization versus Temperature in Pyridinium Ionic Liquids

    DEFF Research Database (Denmark)

    Chaban, V. V.; Prezhdo, O. V.

    2014-01-01

    Electronic polarization and charge transfer effects play a crucial role in thermodynamic, structural, and transport properties of room-temperature ionic liquids (RTILs). These nonadditive interactions constitute a useful tool for tuning physical chemical behavior of RTILs. Polarization and charge...... transfer generally decay as temperature increases, although their presence should be expected over an entire condensed state temperature range. For the first time, we use three popular pyridinium-based RTILs to investigate temperature dependence of electronic polarization in RTILs, based on a nonperiodic...... electronic density description for a cationanion pair. Atom-centered density matrix propagation molecular dynamics, supplemented by a weak coupling to an external bath, is used to simulate the temperature impact on system properties. We show that, quite surprisingly, nonadditivity in the cationanion...

  3. Electrical Impedance of Ionic Polymeric Metal Composites

    Science.gov (United States)

    Leary, S.; Bar-Cohen, Y.

    1999-01-01

    In recent years the use of ionic polymer metal composites such as Nafion-based platinum ionomers have emerged as electroactive polymer materials with great potential for robotics and other applications. An effective activation of these materials requires understanding of their mechanism of operation. Generally, the material needs to be maintained hydrated to assure its electromechanical activity. To allow the control of the response of the material, a study is underway to investigate the electrical response. Particular emphasis is placed on possible electrochemical reactions and deviations from linear dielectric behavior. Currently, efforts are made to determine the necessary drive characteristics of the source to allow low power operation (< or = 1.0 W) of the material as an actuator.

  4. Microregion detection of ionic liquid microemulsions.

    Science.gov (United States)

    Gao, Yanan; Wang, Suqing; Zheng, Liqiang; Han, Shuaibing; Zhang, Xuan; Lu, Deming; Yu, Li; Ji, Yongqiang; Zhang, Gaoyong

    2006-09-15

    Nonaqueous ionic liquid (IL) microemulsion consisting of IL, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), surfactant TX-100, and toluene was prepared and the phase behavior of the ternary system was investigated. Electrical conductivity measurement was used for investigating the microregions of the nonaqueous IL microemulsions. On the basis of the percolation theory, the bmimBF(4)-in-toluene (IL/O), bicontinuous, and toluene-in-bmimBF(4) (O/IL) microregions of the microemulsions were successfully identified using insulative toluene as the titration phase. However, this method was invalid when conductive bmimBF(4) acted as the titration phase. The microregions obtained by conductivity measurements were further proved by electrochemical cyclic voltammetry experiments. The results indicated that the conductivity method was feasible for identifying microstructures of the nonaqueous IL microemulsions. PMID:16765365

  5. Ionic Liquids as Advanced Lubricant Fluids

    Directory of Open Access Journals (Sweden)

    Francisco-José Carrión

    2009-08-01

    Full Text Available Ionic liquids (ILs are finding technological applications as chemical reaction media and engineering fluids. Some emerging fields are those of lubrication, surface engineering and nanotechnology. ILs are thermally stable, non-flammable highly polar fluids with negligible volatility, these characteristics make them ideal candidates for new lubricants under severe conditions, were conventional oils and greases or solid lubricants fail. Such conditions include ultra-high vacuum and extreme temperatures. Other very promising areas which depend on the interaction between IL molecules and material surfaces are the use of ILs in the lubrication of microelectromechanic and nanoelectromechanic systems (MEMS and NEMS, the friction and wear reduction of reactive light alloys and the modification of nanophases.

  6. Graphene terahertz modulators by ionic liquid gating

    CERN Document Server

    Wu, Yang; Qiu, Xuepeng; Liu, Jingbo; Deorani, Praveen; Banerjee, Karan; Son, Jaesung; Chen, Yuanfu; Chia, Elbert E M; Yang, Hyunsoo

    2015-01-01

    Graphene based THz modulators are promising due to the conical band structure and high carrier mobility of graphene. Here, we tune the Fermi level of graphene via electrical gating with the help of ionic liquid to control the THz transmittance. It is found that, in the THz range, both the absorbance and reflectance of the device increase proportionately to the available density of states due to intraband transitions. Compact, stable, and repeatable THz transmittance modulation up to 93% (or 99%) for a single (or stacked) device has been demonstrated in a broad frequency range from 0.1 to 2.5 THz, with an applied voltage of only 3 V at room temperature.

  7. Inorganic materials synthesis in ionic liquids

    Directory of Open Access Journals (Sweden)

    Christoph Janiak

    2014-01-01

    Full Text Available The field of "inorganic materials from ionic liquids" (ILs is a young and dynamically growing research area for less than 10 years. The ionothermal synthesis in ILs is often connected with the preparation of nanomaterials, the use of microwave heating and in part also ultrasound. Inorganic material synthesis in ILs allows obtaining phases which are not accessible in conventional organic or aqueous solvents or with standard methods of solid-state chemistry or under such mild conditions. Cases at hand include "ligand-free" metal nanoparticles without added stabilizing capping ligands, inorganic or inorganic-organic hybrid solid-state compounds, large polyhedral clusters and exfoliated graphene from low-temperature synthesis. There are great expectations that ILs open routes towards new, possibly unknown, inorganic materials with advantageous properties that cannot (or only with great difficulty be made via conventional processes.

  8. Highly stretchable, transparent ionic touch panel

    Science.gov (United States)

    Kim, Chong-Chan; Lee, Hyun-Hee; Oh, Kyu Hwan; Sun, Jeong-Yun

    2016-08-01

    Because human-computer interactions are increasingly important, touch panels may require stretchability and biocompatibility in order to allow integration with the human body. However, most touch panels have been developed based on stiff and brittle electrodes. We demonstrate an ionic touch panel based on a polyacrylamide hydrogel containing lithium chloride salts. The panel is soft and stretchable, so it can sustain a large deformation. The panel can freely transmit light information because the hydrogel is transparent, with 98% transmittance for visible light. A surface-capacitive touch system was adopted to sense a touched position. The panel can be operated under more than 1000% areal strain without sacrificing its functionalities. Epidermal touch panel use on skin was demonstrated by writing words, playing a piano, and playing games.

  9. Solubilities of p-coumaric and caffeic acid in ionic liquids and organic solvents

    International Nuclear Information System (INIS)

    Highlights: ► New solubility data of p-coumaric and caffeic acid in ionic liquids and organic solvents. ► Normal melting point temperature and enthalpy of fusion of p-coumaric and caffeic acid. ► Thermogravimetric analysis for p-coumaric and caffeic acid. ► Correlation with UNIQUAC and NRTL. -- Abstract: The solubilities of two cinnamic acid derivatives, namely p-coumaric acid and caffeic acid, in six 1-alkyl-3-methyl imidazolium based ionic liquids composed of the PF6−, BF4−, TFO− and TF2N− anions, and in two organic solvents, t-pentanol and ethyl acetate, have been measured at the temperature range of about (303 to 317) K. The p-coumaric acid was found to be more soluble than caffeic acid in all studied solvents. Higher solubilities of both acids were observed in the ionic liquids composed of the BF4− and TFO− anions. The increase of the alkyl chain length on the cation invokes a decrease in solubility in the case of hydrophilic ionic liquids composed of BF4− anion, while in the case of hydrophobic ones composed of PF6− anion an increase in the solubility is observed. Between the two organic solvents t-pentanol is better solvent than ethyl acetate for both acids. Moreover, using the van’t Hoff equations the apparent Gibbs energy, enthalpy, and entropy of solution were calculated. Finally, successful correlation of the experimental data was achieved with the UNIQUAC and the NRTL activity coefficient models, while poor predictions of the solubility of the two acids in the organic solvents were obtained with two UNIFAC models

  10. Structural characterization and DFT study of V(IV)O(acac)2 in imidazolium ionic liquids.

    Science.gov (United States)

    Mota, Andreia; Hallett, Jason P; Kuznetsov, Maxim L; Correia, Isabel

    2011-09-01

    We report the structural characterization of vanadyl acetylacetonate in imidazolium room temperature ionic liquids--bbimNTf(2), bmimNTf(2), C(3)OmimNTf(2), bm(2)imNTf(2), bmimPF(6), bmimOTf, bmimBF(4), bmimMeCO(2), bmimMeSO(4), bmimMe(2)PO(4) and bmimN(CN)(2)--and organic solvents. The complex was characterized by visible electronic (Vis) and EPR spectroscopies. VO(acac)(2) shows solvatochromism in the selected ionic liquids and behaves as in organic solvents, evidencing coordination of the ionic liquid anion in the solvents with higher coordinating ability. The Lewis basicity order obtained for the IL anions was: PF(6)(-) < NTf(2)(-) < OTf(-)≈ MeCO(2)(-) < MeSO(4)(-) < BF(4)(-)≈ N(CN)(2)(-) < Me(2)PO(4)(-). The solvent effect on the spectroscopic data was tentatively examined using linear solvation energy relationships based on the Kamlet-Taft solvent scale (α, β and π*), however no suitable correlation was found with all data. The EPR characterization showed the presence of two isomers in bmimOTf, bmimMeCO(2) and bmimMe(2)PO(4), suggesting coordination of the ionic liquid anions in both equatorial and axial positions. The full geometry optimization of cis-/trans-VO(acac)(2)(OTf)(-) and cis-/trans-VO(acac)(2)(OTf)(mmim) structures was done at the B3P86/6-31G* level of theory. The calculations confirm that the anion OTf(-) is able to coordinate to VO(acac)(2) with the trans isomer being more stable than the cis by 4.8 kcal mol(-1). PMID:21789301

  11. Tuning Ionic Transport in Memristive Devices by Graphene with Engineered Nanopores.

    Science.gov (United States)

    Lee, Jihang; Du, Chao; Sun, Kai; Kioupakis, Emmanouil; Lu, Wei D

    2016-03-22

    Memristors, based on inherent memory effects in simple two-terminal structures, have attracted tremendous interest recently for applications ranging from nonvolatile data storage to neuromorphic computing based on non-von Neumann architectures. In a memristor, the ability to modulate and retain the state of an internal variable leads to experimentally observed resistive switching (RS) effects. Such phenomena originate from internal, microscopic ionic migration and associated electrochemical processes that modify the materials' electrical and other physical properties. To optimize the device performance for practical applications with large-size arrays, controlling the internal ionic transport and redox reaction processes thus becomes a necessity, ideally at the atomic scale. Here we show that the RS characteristics in tantalum-oxide-based memristors can be systematically tuned by inserting a graphene film with engineered nanopores. Graphene, with its atomic thickness and excellent impermeability and chemical stability, can be effectively integrated into the device stack and can offer unprecedented capabilities for the control of ionic dynamics at the nanoscale. In this device structure, the graphene film effectively blocks ionic transport and redox reactions; thereby the oxygen vacancies required during the RS process are allowed to transport only through the engineered nanosized openings in the graphene layer, leading to effective modulation of the device performance by controlling the nanopore size in graphene. The roles of graphene as an ion-blocking layer in the device structure were further supported by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and atomistic simulations based on first-principles calculations. PMID:26954948

  12. Layering of ionic liquids on rough surfaces

    Science.gov (United States)

    Sheehan, Alexis; Jurado, L. Andres; Ramakrishna, Shivaprakash N.; Arcifa, Andrea; Rossi, Antonella; Spencer, Nicholas D.; Espinosa-Marzal, Rosa M.

    2016-02-01

    Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact.Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact. Electronic supplementary information (ESI) available: Optimized geometries and sizes for [HMIM] Ntf2, SEM images of the smooth and rough colloids, frequency of occurrence of layering in the resolved force-distance curves for all investigated systems with [HMIM] Ntf2, layer size and layering force measured with a sharp tip on mica for the same IL, and results of the kinetics experiments. See DOI: 10.1039/c5nr07805a

  13. Femtosecond solvation dynamics in a neat ionic liquid and ionic liquid microemulsion: excitation wavelength dependence.

    Science.gov (United States)

    Adhikari, Aniruddha; Sahu, Kalyanasis; Dey, Shantanu; Ghosh, Subhadip; Mandal, Ujjwal; Bhattacharyya, Kankan

    2007-11-01

    Solvation dynamics in a neat ionic liquid, 1-pentyl-3-methyl-imidazolium tetra-flouroborate ([pmim][BF4]) and its microemulsion in Triton X-100 (TX-100)/benzene is studied using femtosecond up-conversion. In both the neat ionic liquid and the microemulsion, the solvation dynamics is found to depend on excitation wavelength (lambda(ex)). The lambda(ex) dependence is attributed to structural heterogeneity in neat ionic liquid (IL) and in IL microemulsion. In neat IL, the heterogeneity arises from clustering of the pentyl groups which are surrounded by a network of cation and anions. Such a nanostructural organization is predicted in many recent simulations and observed recently in an X-ray diffraction study. In an IL microemulsion, the surfactant (TX-100) molecules aggregate in form of a nonpolar peripheral shell around the polar pool of IL. The micro-environment in such an assembly varies drastically over a short distance. The dynamic solvent shift (and average solvation time) in neat IL as well as in IL microemulsions decreases markedly as lambda(ex) increases from 375 to 435 nm. In a [pmim][BF4]/water/TX-100/benzene quaternary microemulsion, the solvation dynamics is slower than that in a microemulsion without water. This is ascribed to the smaller size of the water containing microemulsion. The anisotropy decay in an IL microemulsion is found to be faster than that in neat IL. PMID:17944511

  14. Development of ionic gels using thiol-based monomers in ionic liquid

    Science.gov (United States)

    Ahmed, Kumkum; Naga, Naofumi; Kawakami, Masaru; Furukawa, Hidemitsu

    2016-04-01

    Ionic gels (IGs) using ionic liquids (ILs) can propose diverse applications in the field of optics, sensors and separation have opened wide prospects in materials science. ILs have attracted remarkable interest for gel polymer electrolytes and batteries based on their useful properties such as non-volatility, non-flammability, a wide electrochemical window, high thermal stability and a high ionic conductivity. The formation of gel in IL media makes it possible to immobilize ILs within organic or inorganic matrices and to take advantage of their unique properties in the solid state, thus eliminating some shortcomings related to shaping and risk of leakage. In this work for the first time we used multifunctional thiol monomers having uniform structure and good compatibility with the IL of our interest. Therefore we focused on developing thiol monomer-based IGs using multifunctional thiol monomers and acrylate crosslinkers utilizing thiol-ene reaction between monomer and crosslinking molecules in an IL medium and characterize their physico-chemical properties like thermal, conductive, mechanical properties etc.. This work has been focused mainly to improve the mechanical strength of IGs and make prospects of IGs in tribology and lubricants.

  15. Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

    CERN Document Server

    Stroev, N E

    2016-01-01

    Non-congruent gas-liquid phase transition (NCPT) have been studied in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a \\textit{uniformly compressible} ideal electronic background /BIM($\\sim$)/. The features of NCPT in improved version of the BIM($\\sim$) model for the same mixture on background of \\textit{non-ideal} electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to EoS of electronic and ionic subsystems were used in present calculations within the Gibbs--Guggenheim conditions of non-congruent phase equilibrium.Parameters of critical point-line (CPL) were calculated on the entire range of proportions of mixed ions $0

  16. Application of a density functional approach to nonuniform ionic fluids: the effect of association

    Directory of Open Access Journals (Sweden)

    J.Reszko-Zygmunt

    2004-01-01

    Full Text Available In the present paper we discuss a density functional approach for nonuniform ionic fluids, which takes into account the existence of ion pairs. The theory is based on a fundamental measure theory of hard-spheres, the theory of Gillespie et al., which leads to a more accurate description of the electrostatic part of the grand potential as well as on Wertheim's association theory. The results of model calculations indicate that the inclusion of the associative term in the grand potential leads to the structure of the double layer, which differs from the structure evaluated by neglecting the association. These differences are important at low temperatures only.

  17. Impact of doping on the ionic conductivity of ceria: A comprehensive model

    KAUST Repository

    Wang, Hao

    2013-06-13

    Doped ceria is considered as an electrolyte for solid oxide fuel cell applications. The introduction of dopants in the ceria lattice will affect its electronic structure and, in turn, its ionic conductivity. Simulation of these issues using density functional theory becomes complicated by the random distribution of the constituent atoms. Here we use the generalized gradient approximation with on-site Coulomb interaction in conjunction with the special quasirandom structures method to investigate 18.75% and 25% Y, Gd, Sm, Pr, and La doped ceria. The calculated lattice constants and O migration energies allow us to explain the behavior of the conductivity as obtained in experiments.

  18. Combined theoretical and experimental study of the valence, Rydberg, and ionic states of chlorobenzene.

    Science.gov (United States)

    Palmer, Michael H; Ridley, Trevor; Vrønning Hoffmann, Søren; Jones, Nykola C; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Zhang, Teng; Biczysko, Malgorzata; Baiardi, Alberto; Peterson, Kirk A

    2016-03-28

    New photoelectron (PE) and ultra violet (UV) and vacuum UV (VUV) spectra have been obtained for chlorobenzene by synchrotron study with higher sensitivity and resolution than previous work and are subjected to detailed analysis. In addition, we report on the mass-resolved (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectra of a jet-cooled sample. Both the VUV and REMPI spectra have enabled identification of a considerable number of Rydberg states for the first time. The use of ab initio calculations, which include both multi-reference multi-root doubles and singles configuration interaction (MRD-CI) and time dependent density functional theoretical (TDDFT) methods, has led to major advances in interpretation of the vibrational structure of the ionic and electronically excited states. Franck-Condon (FC) analyses of the PE spectra, including both hot and cold bands, indicate much more complex envelopes than previously thought. The sequence of ionic states can be best interpreted by our multi-configuration self-consistent field computations and also by comparison of the calculated vibrational structure of the B and C ionic states with experiment; these conclusions suggest that the leading sequence is the same as that of iodobenzene and bromobenzene, namely: X(2)B1(3b1 (-1)) < A(2)A2(1a2 (-1)) < B(2)B2(6b2 (-1)) < C(2)B1(2b1 (-1)). The absorption onset near 4.6 eV has been investigated using MRD-CI and TDDFT calculations; the principal component of this band is (1)B2 and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. The other low-lying absorption band near 5.8 eV is dominated by a (1)A1 state, but an underlying weak (1)B1 state (πσ(∗)) is also found. The strongest band in the VUV spectrum near 6.7 eV is poorly resolved and is analyzed in terms of two ππ(∗) states of (1)A1 (higher oscillator strength) and (1)B2 (lower oscillator strength) symmetries, respectively. The calculated vertical

  19. Raman Spectroscopic Study of the Vapour Phase of 1-Methylimidazolium Ethanoate, a Protic Ionic Liquid

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Canongia Lopes, Jose N.; Ferreira, Rui; Rebelo, Luis P. N.; Seddon, Kenneth R.; Tomaszowska, Alina A.

    2010-01-01

    The gas phase over the ionic liquid 1-methylimidazolium ethanoate, [Hmim][O2CCH3], was studied by means of Raman spectroscopy. Raman spectra are presented, the species in the gas phase are identified, and their bands are assigned. The results are interpreted using ab initio quantum mechanical cal...... calculations that also predict vibrational spectra. The obtained data reinforce a previous interpretation, based on FT-ICR mass spectrometric data, that the vapor phase over [Hmim][O2CCH3] consists predominantly of two neutral molecules, monomeric ethanoic acid and 1-methylimidazole....

  20. Ionic and electronic transport properties in dense plasmas by orbital-free density functional theory

    CERN Document Server

    Sjostrom, Travis

    2015-01-01

    We validate the application of our recent orbital-free density functional theory (DFT) approach, [Phys. Rev. Lett. 113, 155006 (2014)], for the calculation of ionic and electronic transport properties of dense plasmas. To this end, we calculate the self-diffusion coefficient, the viscosity coefficient, the electrical and thermal conductivities, and the reflectivity coefficient of hydrogen and aluminum plasmas. Very good agreement is found with orbital-based Kohn-Sham DFT calculations at lower temperatures. Because the method does not scale with temperature, we can produce results at much higher temperatures than is accessible by the Kohn-Sham method. Our results for warm dense aluminum at solid density are inconsistent with the recent experimental results reported by Sperling et al. [Phys. Rev. Lett. 115, 115001 (2015)].