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Sample records for multicomponent liquid mixtures

  1. Evaporation of a Non-Dilute, Multi-Component Liquid Mixture from a Porous Wick

    NASA Astrophysics Data System (ADS)

    Beyhaghi, Saman; Pillai, Krishna M.; Qadah, Diab T.; Dietz, Mark L.

    2010-05-01

    Modeling flow, evaporation and transport of multicomponent liquids remains one of the most challenging problems in porous media studies. Slow evaporation under isothermal conditions of a non-dilute multi-component liquid mixture from a cylindrical porous wick made of sintered polymer beads is studied in this paper. Since the rate of mass evaporation from wick top is much smaller than the rate of capillary-pressure-driven liquid imbibition, the wick is considered fully saturated while the evaporation from wick top is modeled as a boundary effect. A volume-averaged model based on the work by Quintard and Whitaker is employed for the nonlinear species-transport equation inside the fully-saturated porous medium. An implicit finite-difference method is employed to solve the governing equations in a one-dimensional domain representing the cylindrical wick. The Darcy velocity inside the wick is determined from the evaporation rate at the wick-top, which in turn is a function of mole-fractions of all components at the gas-liquid interface. A flux-balance condition, based on the overall mole-balance for each component, is employed to develop a mole-fraction boundary-condition at the wick-bottom interface with a liquid container. Results of this simulation are compared with experiments for a mixture of n-Decane, n-Dodecane and n-Hexadecane; reasonable agreement is observed for the evaporation rate at the wick top, and the component concentration distributions along the wick.

  2. Uphill diffusion in multicomponent mixtures.

    PubMed

    Krishna, Rajamani

    2015-05-21

    Molecular diffusion is an omnipresent phenomena that is important in a wide variety of contexts in chemical, physical, and biological processes. In the majority of cases, the diffusion process can be adequately described by Fick's law that postulates a linear relationship between the flux of any species and its own concentration gradient. Most commonly, a component diffuses down the concentration gradient. The major objective of this review is to highlight a very wide variety of situations that cause the uphill transport of one constituent in the mixture. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of its partner species. Such coupling effects often arise from strong thermodynamic non-idealities. For a quantitative description we need to use chemical potential gradients as driving forces. The transport of ionic species in aqueous solutions is coupled with its partner ions because of the electro-neutrality constraints; such constraints may accelerate or decelerate a specific ion. When uphill diffusion occurs, we observe transient overshoots during equilibration; the equilibration process follows serpentine trajectories in composition space. For mixtures of liquids, alloys, ceramics and glasses the serpentine trajectories could cause entry into meta-stable composition zones; such entry could result in phenomena such as spinodal decomposition, spontaneous emulsification, and the Ouzo effect. For distillation of multicomponent mixtures that form azeotropes, uphill diffusion may allow crossing of distillation boundaries that are normally forbidden. For mixture separations with microporous adsorbents, uphill diffusion can cause supra-equilibrium loadings to be achieved during transient uptake within crystals; this allows the possibility of over-riding adsorption equilibrium for achieving difficult separations.

  3. Uphill diffusion in multicomponent mixtures.

    PubMed

    Krishna, Rajamani

    2015-05-21

    Molecular diffusion is an omnipresent phenomena that is important in a wide variety of contexts in chemical, physical, and biological processes. In the majority of cases, the diffusion process can be adequately described by Fick's law that postulates a linear relationship between the flux of any species and its own concentration gradient. Most commonly, a component diffuses down the concentration gradient. The major objective of this review is to highlight a very wide variety of situations that cause the uphill transport of one constituent in the mixture. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of its partner species. Such coupling effects often arise from strong thermodynamic non-idealities. For a quantitative description we need to use chemical potential gradients as driving forces. The transport of ionic species in aqueous solutions is coupled with its partner ions because of the electro-neutrality constraints; such constraints may accelerate or decelerate a specific ion. When uphill diffusion occurs, we observe transient overshoots during equilibration; the equilibration process follows serpentine trajectories in composition space. For mixtures of liquids, alloys, ceramics and glasses the serpentine trajectories could cause entry into meta-stable composition zones; such entry could result in phenomena such as spinodal decomposition, spontaneous emulsification, and the Ouzo effect. For distillation of multicomponent mixtures that form azeotropes, uphill diffusion may allow crossing of distillation boundaries that are normally forbidden. For mixture separations with microporous adsorbents, uphill diffusion can cause supra-equilibrium loadings to be achieved during transient uptake within crystals; this allows the possibility of over-riding adsorption equilibrium for achieving difficult separations. PMID:25761383

  4. Liquid chromatography and chemometric-assisted spectrophotometric methods for the analysis of two multicomponent mixtures containing cough suppressant drugs.

    PubMed

    El-Gindy, Alaa; Emara, Samy; Mesbah, Mostafa K; Hadad, Ghada M

    2005-01-01

    Three methods were applied for the analysis of 2 multicomponent mixtures containing dextromethorphan hydrobromide, phenylephrine hydrochloride, chlorpheniramine maleate, methylparaben, and propylparaben, together with either sodium benzoate (Mix 1) or ephedrine hydrochloride and benzoic acid (Mix 2). In the first method, liquid chromatography was used for their simultaneous determination using an ODS column with a mobile phase consisting of acetonitrile-phosphate buffer, pH 2.7 (40 + 60, v/v), containing 5mM heptanesulfonic acid sodium salt and ultraviolet (UV) detection at 214 nm. Also, 2 chemometric methods, principal component regression, and partial least squares were used. For both chemometric calibrations, a concentration set of the mixture consisting of each compound in each mixture was prepared in distilled water. The absorbance data in the UV spectra were measured for the 76 or 71 wavelength points in the spectral region 210-240 or 210-224 nm considering the intervals of deltagamma = 0.4 or 0.2 nm for Mix 1 and Mix 2, respectively. The 2 chemometric methods did not require any separation step. These methods were successfully applied for the analysis of the 2 multicomponent combinations in synthetic mixtures and in commercial syrups, and the results were compared with each other. PMID:16152922

  5. The electro-optical characteristics of liquid crystal device in multi-component liquid crystal mixture system with non-contact photo-induced vertical alignment mode

    NASA Astrophysics Data System (ADS)

    Lin, Fa-Hsin; Ho, Czung-Yu; Lee, Jiunn-Yih

    2012-05-01

    In previous studies, we mixed photo-curable acrylic pre-polymer into negative dielectric anisotropy nematic type liquid crystal (N-type LC, NLC) to obtain a NLC/photo-curable acrylic pre-polymer mixture solution (NLC mixture system). After irradiation with UV light of fixed intensity, we successfully fabricated copolymer films with vertical alignment effect among the LC molecules. In this study, we propose a new type of multi-component LC mixture system by mixing chiral smectic type (SmA*) LC with homeotropic texture into NLC/photo-curable acrylic pre-polymer mixture system (NSLC mixture system). Our experimental results revealed that this SmA* LC exhibited the vertical alignment effect associated with LC molecules in the auxiliary LC mixture system. Moreover, we also discovered that altering the main chain type biphenol acrylic pre-polymer had drastic impact on the contrast ratio (CR) of the LC mixture system, with an increase of as much as 73%. More importantly, adding the SmA* LC can evidently increase the anchoring energy of the alignment film surface. We also further performed measurements, analyses, and discussions of electro-optical properties of devices fabricated from the new LC mixture systems.

  6. Multicomponent diffusion in polymeric liquids.

    PubMed Central

    Curtiss, C F; Bird, R B

    1996-01-01

    It is shown how the phase-space kinetic theory of polymeric liquid mixtures leads to a set of extended Maxwell-Stefan equations describing multicomponent diffusion. This expression reduces to standard results for dilute solutions and for undiluted polymers. The polymer molecules are modeled as flexible bead-spring structures. To obtain the Maxwell-Stefan equations, the usual expression for the hydrodynamic drag force on a bead, used in previous kinetic theories, must be replaced by a new expression that accounts explicitly for bead-bead interactions between different molecules. PMID:11607693

  7. New validated liquid chromatographic and chemometrics-assisted UV spectroscopic methods for the determination of two multicomponent cough mixtures in syrup.

    PubMed

    Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

    2008-01-01

    Multivariate spectrophotometric calibration and liquid chromatographic (LC) methods were applied to the determination of 2 multicomponent mixtures containing diprophylline, guaiphenesin, methylparaben, and propylparaben (Mixture 1), or clobutinol, orciprenaline, saccharin sodium, and sodium benzoate (Mixture 2). For the multivariate spectrophotometric calibration methods, principal component regression (PCR) and partial least-squares regression (PLS-1), a calibration set of the mixtures consisting of the components of each mixture was prepared in 0.1 M HCl. Analytical figures of merit such as sensitivity, selectivity, limit of quantitation, and limit of detection were determined for both PLS-1 and PCR. The LC separation was achieved on a reversed-phase C18 analytical column by using isocratic elution with 20 mM potassium dihydrogen phosphate, pH 3.3-acetonitrile (55 + 45, v/v) as the mobile phase and UV detection at 260 and 220 nm for Mixture 1 and Mixture 2, respectively. The proposed methods were validated and successfully applied to the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the 2 multicomponent combinations.

  8. New validated liquid chromatographic and chemometrics-assisted UV spectroscopic methods for the determination of two multicomponent cough mixtures in syrup.

    PubMed

    Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

    2008-01-01

    Multivariate spectrophotometric calibration and liquid chromatographic (LC) methods were applied to the determination of 2 multicomponent mixtures containing diprophylline, guaiphenesin, methylparaben, and propylparaben (Mixture 1), or clobutinol, orciprenaline, saccharin sodium, and sodium benzoate (Mixture 2). For the multivariate spectrophotometric calibration methods, principal component regression (PCR) and partial least-squares regression (PLS-1), a calibration set of the mixtures consisting of the components of each mixture was prepared in 0.1 M HCl. Analytical figures of merit such as sensitivity, selectivity, limit of quantitation, and limit of detection were determined for both PLS-1 and PCR. The LC separation was achieved on a reversed-phase C18 analytical column by using isocratic elution with 20 mM potassium dihydrogen phosphate, pH 3.3-acetonitrile (55 + 45, v/v) as the mobile phase and UV detection at 260 and 220 nm for Mixture 1 and Mixture 2, respectively. The proposed methods were validated and successfully applied to the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the 2 multicomponent combinations. PMID:18376584

  9. Application of an extended Lee-Kesler corresponding-states technique to prediction of vapor-liquid equilibria in multicomponent mixtures containing polar components

    SciTech Connect

    Johnson, J.K.; Rowley, R.L. )

    1989-03-01

    Mixing rules for an extended Lee-Kesler (ELK) corresponding-states method for prediction of thermodynamic properties are presented. The mixing rules, which do not contain adjustable parameters, permit calculation of vapor-liquid equilibria in mixtures containing one or more polar components. While a single heat-of-mixing datum may be included for strongly associating components, generally only pure component properties are used in the calculations. A comparison of calculated bubble-point pressures and equilibrium vaporization ratios to experimental values is made for 26 ternary mixtures (791 points) and 5 quaternary mixtures (175 points). Bubble-point pressures are predicted quite well with ELK (9.1% AAD for ternaries and 7.9% for quaternaries). Composition predictions are difficult to compare in multicomponent systems, but ELK predictions appear to be acceptable on both a system-by-system and an overall AAD basis.

  10. Combined column-mobile phase mixture statistical design optimization of high-performance liquid chromatographic analysis of multicomponent systems.

    PubMed

    Breitkreitz, Márcia C; Jardim, Isabel C S F; Bruns, Roy E

    2009-02-27

    A statistical approach for the simultaneous optimization of the mobile and stationary phases used in reversed-phase liquid chromatography is presented. Mixture designs using aqueous mixtures of acetonitrile (ACN), methanol (MeOH) and tetrahydrofuran (THF) organic modifiers were performed simultaneously with column type optimization, according to a split-plot design, to achieve the best separation of compounds in two sample sets: one containing 10 neutral compounds with similar retention factors and another containing 11 pesticides. Combined models were obtained by multiplying a linear model for column type, C8 or C18, by quadratic or special cubic mixture models. Instead of using an objective response function, combined models were built for elementary chromatographic criteria (retention factors, resolution and relative retention) of each solute or pair of solutes and, after their validation, the global separation was accomplished by means of Derringer's desirability functions. For neutral compounds a 37:12:8:43 (v/v/v/v) percentage mixture of ACN:MeOH:THF:H2O with the C18 column and for pesticides a 15:15:70 (v/v/v) ACN:THF:H2O mixture with the C8 column provide excellent resolution of all peaks.

  11. Development and validation of chemometrics-assisted spectrophotometry and liquid chromatography methods for the simultaneous determination of the active ingredients in two multicomponent mixtures containing chlorpheniramine maleate and phenylpropanolamine hydrochloride.

    PubMed

    Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

    2007-01-01

    Multivariate spectrophotometric calibration and liquid chromatography (LC) methods were used for the simultaneous determination of the active ingredients in 2 multicomponent mixtures containing chlorpheniramine maleate and phenylpropanolamine hydrochloride with ibuprofen and caffeine (mixture 1) or with propyphenazone (mixture 2). For the multivariate spectrophotometric calibration methods, principal component regression (PCR) and partial least squares (PLS-1), a calibration set of the mixtures consisting of the components of each mixture was prepared in distilled water. A leave-1-out cross-validation procedure was used to find the optimum numbers of latent variables. Analytical parameters such as sensitivity, selectivity, analytical sensitivity, limit of quantitation, and limit of detection were determined for both PLS-1 and PCR. The LC method depends on the use of a cyanopropyl column with the mobile phase acetonitrile-12 mM ammonium acetate, pH 5.0 (25 + 75, v/v), for mixture 1 or acetonitrile-10 mM potassium dihydrogen phosphate, pH 4.7 (45 + 55, v/v), for mixture 2; the UV detector was set at 212 nm. In spite of the presence of a high degree of spectral overlap of these components, they were rapidly and simultaneously determined with high accuracy and precision, with no interference from the matrix excipients. The proposed methods were successfully applied to the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the 2 multicomponent combinations.

  12. Multicomponent liquid ion exchange with chabazite zeolites

    SciTech Connect

    Robinson, S.M.; Arnold, W.D. Jr.; Byers, C.W.

    1993-10-01

    In spite of the increasing commercial use of zeolites for binary and multicomponent sorption, the understanding of the basic mass-transfer processes associated with multicomponent zeolite ion-exchange systems is quite limited. This study was undertaken to evaluate Na-Ca-Mg-Cs-Sr ion exchange from an aqueous solution using a chabazite zeolite. Mass-transfer coefficients and equilibrium equations were determined from experimental batch-reactor data for single and multicomponent systems. The Langmuir isotherm was used to represent the equilibrium relationship for binary systems, and a modified Dubinin-Polyani model was used for the multicomponent systems. The experimental data indicate that diffusion through the microporous zeolite crystals is the primary diffusional resistance. Macropore diffusion also significantly contributes to the mass-transfer resistance. Various mass-transfer models were compared to the experimental data to determine mass-transfer coefficients. Effective diffusivities were obtained which accurately predicted experimental data using a variety of models. Only the model which accounts for micropore and macropore diffusion occurring in series accurately predicted multicomponent data using single-component diffusivities. Liquid and surface diffusion both contribute to macropore diffusion. Surface and micropore diffusivities were determined to be concentration dependent.

  13. Lattice Boltzmann model for the simulation of multicomponent mixtures.

    PubMed

    Arcidiacono, S; Karlin, I V; Mantzaras, J; Frouzakis, C E

    2007-10-01

    A lattice Boltzmann (LB) model for the simulation of realistic multicomponent mixtures is constructed. In the hydrodynamic limit, the LB model recovers the equations of continuum mechanics within the mixture-averaged diffusion approximation. The present implementation can be used to simulate realistic mixtures with arbitrary Schmidt numbers and molecular masses of the species. The model is applied to the mixing of two opposed jets of different concentrations and the results are in excellent agreement with a continuum model. An application to the simulation of mixtures in microflows is also presented. Results compare well with existing kinetic theory predictions of the slip coefficient for mixtures in a Couette flow.

  14. Predicting microbial toxicity of nonuniform multicomponent mixtures of organic chemicals

    SciTech Connect

    Peace, J.; Daniel, D.; Nirmalakhandan, N.; Egemen, E.

    1997-04-01

    Three schemes proposed in the literature for analyzing joint toxic effects of multicomponent mixtures on fish, namely the additivity index (AI), the mixture toxicity index (MTI), and the similarity parameter ({lambda}) are evaluated in this study for microbial toxicity. A new approach is proposed to establish acceptance limits for the similarity parameter, {lambda}, based on experimental errors and uncertainties. Quantitative structure activity relationship (QSAR) techniques are then used to develop a model to predict the concentrations of components in mixtures that would jointly cause 50% inhibition of microbial respiration. The application of this approach is demonstrated on the experimental toxicity data of six eight-component organic chemical mixtures on microorganisms.

  15. Multicomponent Diffusion of Penetrant Mixtures in Rubbery Polymers: A Molecular Dynamics Study

    NASA Astrophysics Data System (ADS)

    Bringuier, Stefan; Varady, Mark; Knox, Craig; Cabalo, Jerry; Pearl, Thomas; Mantooth, Brent

    The importance of understanding transport of chemical species across liquid-solid boundaries is of particular interest in the decontamination of harmful chemicals absorbed within polymeric materials. To characterize processes associated with liquid-phase extraction of absorbed species from polymers, it is necessary to determine an appropriate physical description of species transport in multicomponent systems. The Maxwell-Stefan (M-S) formulation is a rigorous description of mass transport in multicomponent solutions, in which, mutual diffusivities determine the degree of relative motion between interacting molecules in response to a chemical potential gradient. The work presented focuses on the determination of M-S diffusivities from molecular dynamics (MD) simulations of nerve agent O-ethyl S-[2(diisopropylamino)ethyl] methylphosphonothioate (VX), water, and methanol mixtures within a poly(dimethylsiloxane) matrix. We investigate the composition dependence of M-S diffusivities and compare the results to values predicted using empirical relations for binary and ternary mixtures. Finally, we highlight the pertinent differences in molecular mechanisms associated with species transport and employ non-equilibrium MD to probe transport across the mixture-polymer interface.

  16. Isentropic Compression of Multicomponent Mixtures of Fuels and Inert Gases

    NASA Technical Reports Server (NTRS)

    Barragan, Michelle; Julien, Howard L.; Woods, Stephen S.; Wilson, D. Bruce; Saulsberry, Regor L.

    2000-01-01

    In selected aerospace applications of the fuels hydrazine and monomethythydrazine, there occur conditions which can result in the isentropic compression of a multicomponent mixture of fuel and inert gas. One such example is when a driver gas such as helium comes out of solution and mixes with the fuel vapor, which is being compressed. A second example is when product gas from an energetic device mixes with the fuel vapor which is being compressed. Thermodynamic analysis has shown that under isentropic compression, the fuels hydrazine and monomethylhydrazine must be treated as real fluids using appropriate equations of state. The appropriate equations of state are the Peng-Robinson equation of state for hydrazine and the Redlich-Kwong-Soave equation of state for monomethylhydrazine. The addition of an inert gas of variable quantity and input temperature and pressure to the fuel compounds the problem for safety design or analysis. This work provides the appropriate thermodynamic analysis of isentropic compression of the two examples cited. In addition to an entropy balance describing the change of state, an enthalpy balance is required. The presence of multicomponents in the system requires that appropriate mixing rules are identified and applied to the analysis. This analysis is not currently available.

  17. The effect of multicomponent diffusion on NAPL dissolution from spherical ternary mixtures.

    PubMed

    Brahma, Priti P; Harmon, Thomas C

    2003-12-01

    This paper investigates the dissolution characteristics of ternary nonaqueous phase liquid (NAPL) mixtures with the goal of comparing the relative contributions of multicomponent (intra-NAPL) diffusion, film transfer and thermodynamic nonideality. These contributions are compared at the pore scale and intermediate scale (several centimeters downstream from the source). Trichloroethene (TCE), tetrachloroethene (PCE) and 1,1,1-trichloroethane (TCA) were selected to model a reasonably ideal mixture; TCE, PCE and octanol were selected as a relevant nonideal mixture. A multicomponent diffusion-based dissolution model incorporating hydrodynamic theory was formulated to estimate intra-NAPL concentration gradients and associated aqueous interfacial concentrations for ideally shaped (spherical) NAPL blobs. Pore scale dissolution times for this model were compared to those generated using the conventional well-mixed NAPL dissolution model, applying the same film transfer boundary condition in both cases. Activity coefficients (spatially and temporally variable for the diffusion model, temporally variable for the well-mixed model) were estimated using UNIFAC. NAPL interfacial concentration histories generated using the pore scale models were used as input in a three-dimensional groundwater transport model (MT3DMS) to compare downstream concentration distributions. For the relatively large NAPL bodies simulated (r=0.6 cm), intra-NAPL diffusion effects were found to be significant at the pore scale and were strongly impacted by the mixture's thermodynamic ideality. At the intermediate scale, and for the conditions tested, modest differences in the simulations suggested that intra-NAPL diffusion effects would be negligible compared to those associated with mixture composition uncertainty, dissolution rate processes related to NAPL-induced permeability effects and hydrodynamic issues associated with flow field heterogeneity.

  18. Uphill diffusion and phase separation in partially miscible multicomponent mixtures

    NASA Astrophysics Data System (ADS)

    He, Ping; Raghavan, Ashwin; Ghoniem, Ahmed

    2015-11-01

    The partially miscible multicomponent mixtures, which are frequently encountered in green chemistry processes, often exhibit complicated behaviors, and are critical to the production rate, energy efficiency, and pollution controls. Recent studies have been mainly focused on phase behaviors. However, the coupled phase equilibrium and transport process, which may be the answer to phase separations observed in experiments, is not well researched. Here, we present a numerical and theoretical study on coupled mixing of heavy oil and supercritical water, and the results of our state-of-art modeling agree with experimental measurements. We find that due to the non-ideal diffusion driving force, (1) strong uphill diffusion of heavy oil fractions occurs, (2) a new heavy oil phase is separated starting from the plait point, and heavy fractions become highly concentrated, and (3) water diffusion initially overshoots in oil, and is expelled lately. Finally, we conclude our analysis applicable to different molecules and conditions. The authors thank Saudi Aramco for supporting this work (contract number 6600023444).

  19. Phase-field theory of multicomponent incompressible Cahn-Hilliard liquids

    NASA Astrophysics Data System (ADS)

    Tóth, Gyula I.; Zarifi, Mojdeh; Kvamme, Bjørn

    2016-01-01

    In this paper, a generalization of the Cahn-Hilliard theory of binary liquids is presented for multicomponent incompressible liquid mixtures. First, a thermodynamically consistent convection-diffusion-type dynamics is derived on the basis of the Lagrange multiplier formalism. Next, a generalization of the binary Cahn-Hilliard free-energy functional is presented for an arbitrary number of components, offering the utilization of independent pairwise equilibrium interfacial properties. We show that the equilibrium two-component interfaces minimize the functional, and we demonstrate that the energy penalization for multicomponent states increases strictly monotonously as a function of the number of components being present. We validate the model via equilibrium contact angle calculations in ternary and quaternary (four-component) systems. Simulations addressing liquid-flow-assisted spinodal decomposition in these systems are also presented.

  20. Phase-field theory of multicomponent incompressible Cahn-Hilliard liquids.

    PubMed

    Tóth, Gyula I; Zarifi, Mojdeh; Kvamme, Bjørn

    2016-01-01

    In this paper, a generalization of the Cahn-Hilliard theory of binary liquids is presented for multicomponent incompressible liquid mixtures. First, a thermodynamically consistent convection-diffusion-type dynamics is derived on the basis of the Lagrange multiplier formalism. Next, a generalization of the binary Cahn-Hilliard free-energy functional is presented for an arbitrary number of components, offering the utilization of independent pairwise equilibrium interfacial properties. We show that the equilibrium two-component interfaces minimize the functional, and we demonstrate that the energy penalization for multicomponent states increases strictly monotonously as a function of the number of components being present. We validate the model via equilibrium contact angle calculations in ternary and quaternary (four-component) systems. Simulations addressing liquid-flow-assisted spinodal decomposition in these systems are also presented. PMID:26871173

  1. Critical Phenomena in Liquid-Liquid Mixtures

    NASA Astrophysics Data System (ADS)

    Jacobs, D. T.

    2000-04-01

    Critical phenomena provide intriguing and essential insight into many issues in condensed matter physics because of the many length scales involved. Large density or concentration fluctuations near a system's critical point effectively mask the identity of the system and produce universal phenomena that have been well studied in simple liquid-vapor and liquid-liquid systems. Such systems have provided useful model systems to test theoretical predictions which can then be extended to more complicated systems. Along various thermodynamic paths, several quantities exhibit a simple power-law dependence close to the critical point. The critical exponents describing these relationships are universal and should depend only on a universality class determined by the order-parameter and spatial dimensionality of the system. Liquid gas, binary fluid mixtures, uniaxial ferromagnetism, polymer-solvent, and protein solutions all belong to the same (Ising model) universality class. The diversity of critical systems that can be described by universal relations indicates that experimental measurements on one system should yield the same information as on another. Our experimental investigations have tested existing theory and also extended universal behavior into new areas. By measuring the coexistence curve, heat capacity, thermal expansion and static light scattering (turbidity) in various liquid-liquid and polymer-solvent systems, we have determined critical exponents and amplitudes that have sometimes confirmed and other times challenged current theory. Recent experiments investigating the heat capacity and light scattering in a liquid-liquid mixture very close to the critical point will be discussed. This research is currently supported by The Petroleum Research Fund and by NASA grant NAG8-1433 with some student support from NSF-DMR 9619406.

  2. Thermodiffusion in multicomponent hydrocarbon mixtures: Experimental investigations and computational analysis.

    PubMed

    VanVaerenbergh, Stefan; Srinivasan, Seshasai; Saghir, M Ziad

    2009-09-21

    In an unprecedented experimental investigation, a ternary and a four component hydrocarbon mixture at high pressure have been studied in a nearly convection free environment to understand the thermodiffusion process. A binary mixture has also been investigated in this environment. Experimental investigations of the three mixtures have been conducted in space onboard the spacecraft FOTON-M3 thereby isolating the gravity-induced convection that otherwise interferes with thermodiffusion experiments on Earth. The experimental results have also been used to test a thermodiffusion model that has been calibrated based on the results of previous experimental investigations. It was found that with an increase in the number of components in the mixtures, the performance of the thermodiffusion model deteriorated. Computational analysis was also made to estimate the possible sources of errors. Simulations showed that the vibrations of the spacecraft could influence the estimates of thermodiffusion factors. It was also found that they are sensitive to slight variations in the temperature of the mixture.

  3. Mechano-chemistry; diffusion in multicomponent compressible mixtures

    NASA Astrophysics Data System (ADS)

    Danielewski, Marek; Wierzba, Bartłomiej

    2008-02-01

    In the present work we derive the volume continuity equation and demonstrate its use to define the volume frame of reference in the multicomponent, compressible systems. The volume velocity (material velocity) is a unique frame of reference for all internal forces and processes, e.g., the mass diffusion, heat flow, etc. No basic changes are required in the foundations of linear irreversible thermodynamics except recognizing the need to add volume to the usual list of extensive physical properties undergoing transport in every continuum. The volume fixed frame of reference allows the translation of the Newton’s discrete mass-point molecular mechanics into continuum mechanics and the use of the Cauchy linear momentum equation of fluid mechanics and Navier-Lamé equation of mechanics of solids. Our proposed modifications of Navier-Lamé and energy conservation equations are self-consistent with the literature for solid-phase continua dating back to the classical interdiffusion experiments of Kirkendall and their subsequent interpretation by Darken in terms of diffuse volume transport. We do show that the local diffusion processes do not change the centre of mass of the system and that the stress and viscosity depend only on the local volume velocity.

  4. Surface fractionation of multi-component oil mixtures

    SciTech Connect

    Peterson, J.W.

    1985-01-01

    An investigation is made of fractionation which occurs in oil mixtures as they spread over water surfaces under the control of surface forces. Mixtures of polydimethylsiloxane (PDMS) and tetradecane were selected for the experiments because of their widely disparate spreading properties and their low susceptibility to loss by evaporation and dissolution. An experimental apparatus and technique were developed which allowed quantitative measurement of the composition of the PDMS-tetradecane oil film as a function of radial position, while effectively eliminating the undesired losses. The results of experiments done with this system provide positive substantiation of the occurrence of fractionation, and indicate that a preferential spreading mechanism is involved. Additional fractionation measurements are made for an oil mixture of toluene, octane, and decane. A model describes the fractionation process as a multi-stage batch-charged separation. Knowledge of the volumetric flow field of the spreading oil film is required for solution of the modelling equations. This knowledge is gained by measuring the oil film thickness profiles experimentally and then empirically modelling them. A new method is developed for determining the oil film thickness using polychromatic interference fringes. The resulting thickness profiles display similarity when appropriately scaled. This similarity provides experimental verification of a spreading law by Fay (1969) and a theoretical analysis by Camp (1985). The transformed profiles are well modelled by power law curves. The thickness model yields flow-field information for the fractionation model, which subsequently produces very close fits to the fractionation data.

  5. Liquid class predictor for liquid handling of complex mixtures

    DOEpatents

    Seglke, Brent W.; Lekin, Timothy P.

    2008-12-09

    A method of establishing liquid classes of complex mixtures for liquid handling equipment. The mixtures are composed of components and the equipment has equipment parameters. The first step comprises preparing a response curve for the components. The next step comprises using the response curve to prepare a response indicator for the mixtures. The next step comprises deriving a model that relates the components and the mixtures to establish the liquid classes.

  6. Water uptake of multicomponent organic mixtures and their influence on hygroscopicity of inorganic salts.

    PubMed

    Wang, Yuanyuan; Jing, Bo; Guo, Yucong; Li, Junling; Tong, Shengrui; Zhang, Yunhong; Ge, Maofa

    2016-07-01

    The hygroscopic behaviors of atmospherically relevant multicomponent water soluble organic compounds (WSOCs) and their effects on ammonium sulfate (AS) and sodium chloride were investigated using a hygroscopicity tandem differential mobility analyzer (HTDMA) in the relative humidity (RH) range of 5%-90%. The measured hygroscopic growth was compared with predictions from the Extended-Aerosol Inorganics Model (E-AIM) and Zdanovskii-Stokes-Robinson (ZSR) method. The equal mass multicomponent WSOCs mixture containing levoglucosan, succinic acid, phthalic acid and humic acid showed gradual water uptake without obvious phase change over the whole RH range. It was found that the organic content played an important role in the water uptake of mixed particles. When organic content was dominant in the mixture (75%), the measured hygroscopic growth was higher than predictions from the E-AIM or ZSR relation, especially under high RH conditions. For mass fractions of organics not larger than 50%, the hygroscopic growth of mixtures was in good agreement with model predictions. The influence of interactions between inorganic and organic components on the hygroscopicity of mixed particles was related to the salt type and organic content. These results could contribute to understanding of the hygroscopic behaviors of multicomponent aerosol particles. PMID:27372129

  7. Bonding and structure in dense multi-component molecular mixtures

    DOE PAGES

    Meyer, Edmund R.; Ticknor, Christopher; Bethkenhagen, Mandy; Hamel, Sebastien; Redmer, Ronald; Kress, Joel D.; Collins, Lee A.

    2015-10-30

    We have performed finite-temperature density functional theory molecular dynamics simulations on dense methane, ammonia, and water mixtures (CH4:NH3:H2O) for various compositions and temperatures (2000 K ≤ T ≤ 10000 K) that span a set of possible conditions in the interiors of ice-giant exoplanets. The equation-of-state, pair distribution functions, and bond autocorrelation functions (BACF) were used to probe the structure and dynamics of these complex fluids. In particular, an improvement to the choice of the cutoff in the BACF was developed that allowed analysis refinements for density and temperature effects. We note the relative changes in the nature of these systemsmore » engendered by variations in the concentration ratios. As a result, a basic tenet emerges from all these comparisons that varying the relative amounts of the three heavy components (C,N,O) can effect considerable changes in the nature of the fluid and may in turn have ramifications for the structure and composition of various planetary layers.« less

  8. Bonding and structure in dense multi-component molecular mixtures

    SciTech Connect

    Meyer, Edmund R.; Ticknor, Christopher; Bethkenhagen, Mandy; Hamel, Sebastien; Redmer, Ronald; Kress, Joel D.; Collins, Lee A.

    2015-10-30

    We have performed finite-temperature density functional theory molecular dynamics simulations on dense methane, ammonia, and water mixtures (CH4:NH3:H2O) for various compositions and temperatures (2000 K ≤ T ≤ 10000 K) that span a set of possible conditions in the interiors of ice-giant exoplanets. The equation-of-state, pair distribution functions, and bond autocorrelation functions (BACF) were used to probe the structure and dynamics of these complex fluids. In particular, an improvement to the choice of the cutoff in the BACF was developed that allowed analysis refinements for density and temperature effects. We note the relative changes in the nature of these systems engendered by variations in the concentration ratios. As a result, a basic tenet emerges from all these comparisons that varying the relative amounts of the three heavy components (C,N,O) can effect considerable changes in the nature of the fluid and may in turn have ramifications for the structure and composition of various planetary layers.

  9. Phase transitions and separations in a distorted liquid crystalline mixture.

    PubMed

    Kasch, Nicholas; Dierking, Ingo

    2015-08-14

    A theoretical method is proposed for modelling phase transitions and phase ranges in a multi-component liquid crystalline mixture where the liquid crystal structure is distorted and defects are formed. This method employs the Maier-Saupe and Kobayashi-McMillan theories of liquid crystalline ordering and the Flory-Huggins theory of mixtures. It builds on previous work on mixed systems that can form smectic-A and nematic phases by incorporating "distortion factors" into the expression for the local free energy of the mixture, which account for the effects of a deviation of the liquid crystal structure from the uniform nematic and smectic-A states. The method allows a simple description of chiral defect phases such as the blue phase and the twist grain boundary phase. In a previous work, it was shown that a model of the blue phase along these lines could effectively explain the observed effect whereby an added guest compound can stabilize the phase by separating into the high energy defect regions of the structure. It is shown here that with the correct choice of guest material a similar effect could be observed for the twist grain boundary phase.

  10. Phase transitions and separations in a distorted liquid crystalline mixture

    NASA Astrophysics Data System (ADS)

    Kasch, Nicholas; Dierking, Ingo

    2015-08-01

    A theoretical method is proposed for modelling phase transitions and phase ranges in a multi-component liquid crystalline mixture where the liquid crystal structure is distorted and defects are formed. This method employs the Maier-Saupe and Kobayashi-McMillan theories of liquid crystalline ordering and the Flory-Huggins theory of mixtures. It builds on previous work on mixed systems that can form smectic-A and nematic phases by incorporating "distortion factors" into the expression for the local free energy of the mixture, which account for the effects of a deviation of the liquid crystal structure from the uniform nematic and smectic-A states. The method allows a simple description of chiral defect phases such as the blue phase and the twist grain boundary phase. In a previous work, it was shown that a model of the blue phase along these lines could effectively explain the observed effect whereby an added guest compound can stabilize the phase by separating into the high energy defect regions of the structure. It is shown here that with the correct choice of guest material a similar effect could be observed for the twist grain boundary phase.

  11. Liquid-Vapor Equilibrium of Multicomponent Cryogenic Systems

    NASA Technical Reports Server (NTRS)

    Thompson, W. Reid; Calado, Jorge C. G.; Zollweg, John A.

    1990-01-01

    Liquid-vapor and solid-vapor equilibria at low to moderate pressures and low temperatures are important in many solar system environments, including the surface and clouds of Titan, the clouds of Uranus and Neptune, and the surfaces of Mars and Triton. The familiar cases of ideal behavior are limiting cases of a general thermodynamic representation for the vapor pressure of each component in a homogeneous multicomponent system. The fundamental connections of laboratory measurements to thermodynamic models are through the Gibbs-Duhem relation and the Gibbs-Helmholtz relation. Using laboratory measurements of the total pressure, temperature, and compositions of the liquid and vapor phases at equilibrium, the values of these parameters can be determined. The resulting model for vapor-liquid equilibrium can then conveniently and accurately be used to calculate pressures, compositions, condensation altitudes, and their dependencies on changing climatic conditions. A specific system being investigated is CH4-C2H6-N2, at conditions relevant to Titan's surface and atmosphere. Discussed are: the modeling of existing data on CH4-N2, with applications to the composition of Titan's condensate clouds; some new measurements on the CH4-C2H6 binary, using a high-precision static/volumetric system, and on the C2H6-N2 binary, using the volumetric system and a sensitive cryogenic flow calorimeter; and describe a new cryogenic phase-equilibrium vessel with which we are beginning a detailed, systematic study of the three constituent binaries and the ternary CH4-C2H6-N2 system at temperatures ranging from 80 to 105 K and pressures from 0.1 to 7 bar.

  12. An empirical method for calculating the viscosities of hydrocarbon liquids and liquid mixtures

    SciTech Connect

    Peng, D.Y.; Vermani, R.

    1987-01-01

    The viscosities of pure liquid normal alkanes ranging from propane to n-tetradecane are correlated using the Peng-Robinson equation of state in conjunction with Hildebrand's empirical theory of fluidity. A mixing rule and an excess fluidity function are proposed. Simulated viscosity data generated from the corresponding states method of Ely and Hanley are used to determine the binary interaction parameters needed in the excess function which has its form based on the Wilson equation. The procedure has been used to calculate the viscosities of binary mixtures and simulated multicomponent liquid n-alkane mixtures involving the above-mentioned components at temperatures to 444 K and pressures to 200 bar. The results are compared with the predicted values obtained from the corresponding states method. The procedure is simple to use and it has an accuracy comparable to that of the theoretically based but more elaborate method.

  13. Flash evaporation of liquid monomer particle mixture

    DOEpatents

    Affinito, John D.; Darab, John G.; Gross, Mark E.

    1999-01-01

    The present invention is a method of making a first solid composite polymer layer. The method has the steps of (a) mixing a liquid monomer with particles substantially insoluble in the liquid monomer forming a monomer particle mixture; (b) flash evaporating the particle mixture and forming a composite vapor; and (c) continuously cryocondensing said composite vapor on a cool substrate and cross-linking the cryocondensed film thereby forming the polymer layer.

  14. Flash evaporation of liquid monomer particle mixture

    DOEpatents

    Affinito, J.D.; Darab, J.G.; Gross, M.E.

    1999-05-11

    The present invention is a method of making a first solid composite polymer layer. The method has the steps of (a) mixing a liquid monomer with particles substantially insoluble in the liquid monomer forming a monomer particle mixture; (b) flash evaporating the particle mixture and forming a composite vapor; and (c) continuously cryocondensing said composite vapor on a cool substrate and cross-linking the cryocondensed film thereby forming the polymer layer. 3 figs.

  15. IDENTIFICATION AND EXPERIMENTAL DATABASE FOR BINARY AND MULTICOMPONENT MIXTURES WITH POTENTIAL FOR INCREASING OVERALL CYCLE EFFICIENCY

    SciTech Connect

    Stephen M Bajorek; J. Schnelle

    2002-05-01

    This report describes an experimental investigation designed to identify binary and multicomponent mixture systems that may be for increasing the overall efficiency of a coal fired unit by extracting heat from flue gases. While ammonia-water mixtures have shown promise for increasing cycle efficiencies in a Kalina cycle, the costs and associated range of thermal conditions involved in a heat recovery system may prohibit its use in a relatively low temperature heat recovery system. This investigation considered commercially available non-azeotropic binary mixtures with a boiling range applicable to a flue gas initially at 477.6 K (400 F) and developed an experimental database of boiling heat transfer coefficients for those mixtures. In addition to their potential as working fluids for increasing cycle efficiency, cost, ease of handling, toxicity, and environmental concerns were considered in selection of the mixture systems to be examined experimentally. Based on this review, water-glycol systems were identified as good candidates. However, previous investigations of mixture boiling have focused on aqueous hydrocarbon mixtures, where water is the heaviest component. There have been few studies of water-glycol systems, and those that do exist have investigated boiling on plain surfaces only. In water-glycol systems, water is the light component, which makes these systems unique compared to those that have been previously examined. This report examines several water-glycol systems, and documents a database of experimental heat transfer coefficients for these systems. In addition, this investigation also examines the effect of an enhanced surface on pool boiling in water-glycol mixtures, by comparing boiling on a smooth surface to boiling on a Turbo IIIB. The experimental apparatus, test sections, and the experimental procedures are described. The mixture systems tested included water-propylene glycol, water-ethylene glycol, and water-diethylene glycol. All

  16. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Jing, Bo; Tong, Shengrui; Liu, Qifan; Li, Kun; Wang, Weigang; Zhang, Yunhong; Ge, Maofa

    2016-03-01

    Water-soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, knowledge on the water uptake behavior of internally mixed WSOC aerosols remains limited. Here, the hygroscopic properties of single components such as levoglucosan, oxalic acid, malonic acid, succinic acid, phthalic acid, and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid, and phthalic acid have a strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppressing its crystallization completely during the drying process. The phase behaviors of oxalic acid/levoglucosan mixed particles are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with the Universal Quasi-Chemical Functional Group Activity Coefficient (UNIFAC) method and Zdanovskii-Stokes-Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a crystalline solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH compared to the model predictions based on reasonable oxalic acid phase assumption. Organic mixture has more complex effects on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan account for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing the phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake

  17. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Jing, B.; Tong, S. R.; Liu, Q. F.; Li, K.; Wang, W. G.; Zhang, Y. H.; Ge, M. F.

    2015-08-01

    Water soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, water uptake behavior of internally mixed WSOC aerosols remains limited characterization. Here, the hygroscopic properties of single component such as levoglucosan, oxalic acid, malonic acid, succinic acid and phthalic acid and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid and phthalic acid have strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppress its crystallization completely. The interactions between oxalic acid and levoglucosan are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with UNIFAC method and Zdanovskii-Stokes-Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH due to positive chemical interactions between solutes. Organic mixture has more complex effect on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan accounts for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake under high RH conditions and thus affect the cloud condensation nuclei (CCN) activity, optical properties and chemical reactivity of atmospheric particles.

  18. Critical adsorption and colloidal interaction in multi-component liquids

    NASA Astrophysics Data System (ADS)

    Alam, Sharmine; Mukhopadhyay, Ashis

    2014-03-01

    We studied critical adsorption on colloidal nanoparticles in binary liquid mixture of 2,6 lutidine + water by using fluorescence correlation spectroscopy (FCS). Our results indicated that the adsorbed film thickness is of the order of correlation length associated with concentration fluctuations. The excess adsorption per unit area increases following a power law in reduced temperature with an exponent of -1, which is the mean-field value for the bulk susceptibility exponent. The measurements at higher particle volume fractions, where phenomena such as the particle-particle interaction, self-assembly, ternary phase separation become important will be presented. Acknowledgements are made to the Donors of the American Chemical Society Petroleum Research fund (PRF # 51694-ND10) for support of this research.

  19. Brillouin scattering study of equation of state of multicomponent liquids: Model oil samples

    SciTech Connect

    Bohidar, H.B.

    1988-10-01

    Brillouin scattering technique has been used to measure the pressure dependence of sound velocity v/sub s/(P) in model oil samples (each containing 5-hydrocarbon liquids) at room temperature T = 20/sub 1/ /sup 0/C. Experimental results are reported on two blends of model oil, each containing a mixture of n-heptane, n-tetradecane, cyclo-hexane, benzene, and toluene in different volume fractions. The compositions of these two differed in their cyclohexane and toluene contents. The pressure dependence of v/sub s/(P) has been measured up to 815 bars and the results could be least-square fitted to v/sub s/(P) = A/sub 0/+A/sub 1/P+A/sub 2/P/sup 2/ within the limits of experimental error ( +- 1%). The modified Tait's equation and linear pressure dependence of bulk modulii have been used in consistence with an earlier work to interpret the parabolic pressure dependence of v/sub s/(P). This yields the values of Tait parameters (B and C) and hence allows the explicit pressure dependence of density and compressibility of these multicomponent liquids to be evaluated.

  20. Emergence of life from multicomponent mixtures of chemicals: the case for experiments with cycling physicochemical gradients.

    PubMed

    Spitzer, Jan

    2013-04-01

    The emergence of life from planetary multicomponent mixtures of chemicals is arguably the most complicated and least understood natural phenomenon. The fact that living cells are non-equilibrium systems suggests that life can emerge only from non-equilibrium chemical systems. From an astrobiological standpoint, non-equilibrium chemical systems arise naturally when solar irradiation strikes rotating surfaces of habitable planets: the resulting cycling physicochemical gradients persistently drive planetary chemistries toward "embryonic" living systems and an eventual emergence of life. To better understand the factors that lead to the emergence of life, I argue for cycling non-equilibrium experiments with multicomponent chemical systems designed to represent the evolving chemistry of Hadean Earth ("prebiotic soups"). Specifically, I suggest experimentation with chemical engineering simulators of Hadean Earth to observe and analyze (i) the appearances and phase separations of surface active and polymeric materials as precursors of the first "cell envelopes" (membranes) and (ii) the accumulations, commingling, and co-reactivity of chemicals from atmospheric, oceanic, and terrestrial locations.

  1. Quantitative NIR Raman analysis in liquid mixtures.

    PubMed

    Sato-Berrú, R Ysacc; Medina-Valtierra, Jorge; Medina-Gutiérrez, Cirilo; Frausto-Reyes, Claudio

    2004-08-01

    The capability to obtain quantitative information of a simple way from Raman spectra is a subject of considerable interest. In this work, this is demonstrated for mixtures of ethanol with water and rhodamine-6G (R-6G) with methanol, which were analyzed directly in glass vessel. The Raman intensities and a simple mathematical model have been used and applied for the analysis of liquid samples. It is starting point to generate a general expression, from the experimental spectra, as the sum of the particular expression for each pure compound allow us to obtain an expression for the mixtures which can be used for determining concentrations, from the Raman spectrum, of the mixture.

  2. Evaporation of Liquid Hydrocarbon Mixtures on Titan

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, Adrienn; Chevrier, V. F.; Rivera-Valentin, E. G.; Singh, S.; Roe, L. A.; Wagner, A.

    2013-10-01

    Besides Earth, Titan is the only other known planetary body with proven stable liquids on its surface. The hydrological cycle of these liquid hydrocarbon mixtures is critical in understanding Titan’s atmosphere and surface features. Evaporation of liquid surface bodies has been indirectly observed as shoreline changes from measurements by Cassini ISS and RADAR (Hayes et al. 2011, Icarus 211, 655-671; Turtle et al. 2011, Science 18, 1414-1417.), but the long seasons of Saturn strongly limit the time span of these observations and their validity over the course of an entire Titan year. Using a novel Titan simulation chamber, the evaporation rate of liquid methane and dissolved nitrogen mixture under Titan surface conditions was derived (Luspay-Kuti et al. 2012, GRL 39, L23203), which is especially applicable to low latitude transient liquids. Polar lakes, though, are expected to be composed of a variety of hydrocarbons, primarily a mixture of ethane and methane (e.g. Cordier et al. 2009, ApJL 707, L128-L131). Here we performed laboratory simulations of ethane-methane mixtures with varying mole fraction under conditions suitable for the polar regions of Titan. We will discuss results specifically addressing the evaporation behavior as the solution becomes increasingly ethane dominated, providing quantitative values for the evaporation rate at every step. These laboratory results are relevant to polar lakes, such as Ontario Lacus, and can shed light on their stability.

  3. The New TLC Method for Separation and Determination of Multicomponent Mixtures of Plant Extracts

    PubMed Central

    Matysik, Elżbieta; Woźniak, Anna; Paduch, Roman; Rejdak, Robert; Polak, Beata; Donica, Helena

    2016-01-01

    The new mode of two-dimensional gradient thin layer chromatography (MGD-2D TLC) has been presented. Short distance development of sample in the first dimension leads to formation of the preconcentrated narrow zones. They are consecutively separated in the second dimension with the mobile phase gradient in several steps of development until the eluent reaches the further end of the chromatographic plate. The use of the above-mentioned technique allows isolating and then identifying the compounds of various polarity from the multicomponent mixture. The practical application of two-dimensional gradient thin layer chromatography has been performed for isolation of the two plant (Juniperus and Thymus) oils components as the examples of test mixtures. The experiments have been carried out with the use of silica gel plates as well as a normal phase condition. The results of solute separation with isocratic one-dimensional thin layer chromatography system have been compared with those of two-dimensional gradient system. It has been observed that application of the latter mode leads to almost triplicated number of zones in comparison with the former one. It is purposeful to apply the proposed mode to control the purity of the dominant component or components of the mixture. PMID:26981317

  4. The New TLC Method for Separation and Determination of Multicomponent Mixtures of Plant Extracts.

    PubMed

    Matysik, Elżbieta; Woźniak, Anna; Paduch, Roman; Rejdak, Robert; Polak, Beata; Donica, Helena

    2016-01-01

    The new mode of two-dimensional gradient thin layer chromatography (MGD-2D TLC) has been presented. Short distance development of sample in the first dimension leads to formation of the preconcentrated narrow zones. They are consecutively separated in the second dimension with the mobile phase gradient in several steps of development until the eluent reaches the further end of the chromatographic plate. The use of the above-mentioned technique allows isolating and then identifying the compounds of various polarity from the multicomponent mixture. The practical application of two-dimensional gradient thin layer chromatography has been performed for isolation of the two plant (Juniperus and Thymus) oils components as the examples of test mixtures. The experiments have been carried out with the use of silica gel plates as well as a normal phase condition. The results of solute separation with isocratic one-dimensional thin layer chromatography system have been compared with those of two-dimensional gradient system. It has been observed that application of the latter mode leads to almost triplicated number of zones in comparison with the former one. It is purposeful to apply the proposed mode to control the purity of the dominant component or components of the mixture. PMID:26981317

  5. Minimum Error Fickian Diffusion Coefficients for Mass Diffusion in Multicomponent Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Subramaniam, S.

    1999-04-01

    Mass diffusion in multicomponent gas mixtures is governed by a coupled system of linear equations for the diffusive mass fluxes in terms of thermodynamic driving forces, known as the generalized Stefan-Maxwell equation. In computations of mass diffusion in multicomponent gas mixtures, this coupling between the different components results in considerable computational overhead. Consequently, simplified diffusion models for the diffusive mass fluxes as explicit functions of the driving forces are an attractive alternative. These models can be interpreted as an approximate solution to the Stefan-Maxwell equation. Simplified diffusion models require the specification of “effective” diffusion coefficients which are usually expressed as functions of the binary diffusion coefficients of each species pair in the mixture. Current models for the effective diffusion coefficients are incapable of providing a priori control over the error incurred in the approximate solution. In this paper a general form for diagonal approximations is derived, which accounts for the requirement imposed by the special structure of the Stefan-Maxwell equation that such approximations be constructed in a reduced-dimensional subspace. In addition, it is shown that current models can be expressed as particular cases of two general forms, but not all these models correspond to the general form for diagonal approximations. A new minimum error diagonal approximation (MEDA) model is proposed, based on the criterion that the diagonal approximation minimize the error in the species velocities. Analytic expressions are derived for the MEDA model's effective diffusion coefficients based on this criterion. These effective diffusion coefficients automatically give the correct solution in two important limiting cases: for that of a binary mixture, and for the case of arbitrary number of components with identical binary diffusivities. Although these minimum error effective diffusion

  6. Liquid-liquid distribution of aromatic α-amino acids in multicomponent systems

    NASA Astrophysics Data System (ADS)

    Korenman, Ya. I.; Mokshina, N. Ya.; Pakhomova, O. A.

    2010-02-01

    Distribution coefficients and recovery factors of phenylalanine, tyrosine, and tryptophan are measured in extraction systems with butanol, pentanol, acetone, and ethyl acetate, their binary and ternary mixtures, and water-soluble polymers. Extraction conditions—extractant composition, salting-out agents, and pH—are optimized. Efficient systems providing maximum quantitative characteristics of the process of liquid-liquid distribution of aromatic α-amino acids are proposed.

  7. Precursors in gas-liquid mixtures

    NASA Astrophysics Data System (ADS)

    Gasenko, V. G.; Gorelik, R. S.; Nakoryakov, V. E.; Timkin, L. S.

    2013-10-01

    Two types of precursors propagating at the speed of sound in a pure liquid have been revealed in the experiments on the evolution of pressure pulses in a gas-liquid mixture; at the same time, the main pressure pulse propagates at a low equilibrium speed of sound and its evolution is described by the Burgers-Korteweg-de Vries equation. The first high-frequency precursor is a complete analog of a classical Sommerfeld precursor, because the resonance dispersion equation for a bubble mixture coincides with that for insulators in the Lorentz model, and oscillates at a frequency close to the "plasma frequency." The second low-frequency precursor has been revealed in this work. The frequency of the low-frequency precursor is close to the resonance frequency of pulsations of bubbles, which is almost an order of magnitude lower than the frequency of the high-frequency precursor. The low-frequency precursor has a much larger amplitude of pulsations and smaller damping and is not described within the homogeneous model of the gas-liquid mixture. The observed phenomenon of low-frequency precursors has been explained within a simple heterogeneous model of a bubble liquid.

  8. Unmixing Multi-Component Magnetic Mixtures in Geologic Materials Using First Order Reversal Curve Diagrams

    NASA Astrophysics Data System (ADS)

    Lascu, I.; Harrison, R. J.; Li, Y.; Muraszko, J.; Channell, J. E. T.; Piotrowski, A. M.; Hodell, D. A.; Necula, C.; Panaiotu, C. G.

    2015-12-01

    We have developed a magnetic unmixing method based on principal component analysis (PCA) of first-order reversal curve (FORC) diagrams. PCA provides an objective and robust statistical framework for unmixing, because it represents data variability as a linear combination of a limited number of principal components that are derived purely on the basis of natural variations contained within the dataset. For PCA we have resampled FORC distributions on grids that capture diagnostic signatures of magnetic domain states. Individual FORC diagrams were then recast as linear combinations of end-member (EM) FORC diagrams, located at user-defined positions in PCA space. The EM selection is guided by constraints derived from physical modeling, and is imposed by data scatter. To test our model, we have investigated temporal variations of two EMs in bulk North Atlantic sediment cores collected from the Rockall Trough and the Iberian Continental Margin. Sediments from these sites contain a mixture of magnetosomes and granulometrically distinct detrital magnetite. We have also quantified the spatial variation of three EM components in surficial sediments along the flow path of the North Atlantic Deep Water (NADW). These samples were separated into granulometric fractions, which also assisted in constraining EM definition. The unmixing model reveals systematic variations in EM relative abundance as a function of distance along NADW flow. Finally, we have applied PCA to the combined dataset of Rockall Trough and NADW sediments, which can be recast as a four-EM mixture, providing enhanced discrimination between components. Our method forms the foundation of a general solution to the problem of unmixing multi-component magnetic mixtures, a fundamental task of rock magnetic studies.

  9. UV sensors based on liquid crystals mixtures

    NASA Astrophysics Data System (ADS)

    Chanishvili, Andro; Petriashvili, Gia; Chilaya, Guram; Barberi, Riccardo; De Santo, Maria P.; Matranga, Mario A.; Ciuchi, F.

    2006-04-01

    The Erythemal Response Spectrum is a scientific expression that describes the sensitivity of the skin to the ultraviolet radiation. The skin sensitivity strongly depends on the UV wavelength: a long exposition to UV radiation causes erythema once a threshold dose has been exceeded. In the past years several devices have been developed in order to monitor the UV exposure, most of them are based on inorganic materials that are able to mimic the human skin behaviour under UV radiation. We present a new device based on liquid crystals technology. The sensor is based on a liquid crystalline mixture that absorbs photons at UV wavelength and emits them at a longer one. This system presents several innovative features: the absorption range of the mixture can be varied to be sensitive to different wavelengths, the luminescence intensity can be tuned, the system can be implemented on flexible devices.

  10. Direct Numerical Simulation of Transitional Multicomponent-Species Gaseous and Multicomponent-Liquid Drop-Laden Mixing

    NASA Technical Reports Server (NTRS)

    Selle, Laurent C.; Bellan, Josette

    2006-01-01

    A model of multicomponent-liquid (MC-liquid) drop evaporation in a three-dimensional mixing layer is here exercised at larger Reynolds numbers than in a previous study, and transitional states are obtained. The gas phase is followed in an Eulerian frame and the multitude of drops is described in a Lagrangian frame. Complete coupling between phases is included with source terms in the gas conservation equations accounting for the drop/flow interaction in terms of drop drag, drop heating and species evaporation. The liquid composition, initially specified as a single-Gamma (SG) probability distribution function (PDF) depending on the molar mass is allowed to evolve into a linear combination of two SGPDFs, called the double-Gamma PDF (DGPDF). The compositions of liquid and vapor emanating from the drops are calculated through four moments of the DGPDFs, which are drop-specific and location-specific, respectively. The mixing layer is initially excited to promote the double pairing of its four initial spanwise vortices into an ultimate vortex in which small scales proliferate. Simulations are performed for four liquids of different compositions and the effect of the initial mass loading and initial free-stream gas temperature are explored. For reference, Simulations are also performed for gaseous multicomponent mixing layers for which the effect of Reynolds number is investigated. The results encompass examination of the global layer characteristics, flow visualizations and homogeneous-plane statistics at transition. Comparisons are performed with previous pre-transitional MC-liquid simulations and with transitional single-component (SC) liquid studies. It is found that MCC flows at transition, the classical energy cascade is of similar strength, but that the smallest scales contain orders of magnitude less energy than SC flows, which is confirmed by the larger viscous dissipation in the former case. Contrasting to pre-transitional MC flows, the vorticity and drop

  11. Transthyretin complexes with curcumin and bromo-estradiol: evaluation of solubilizing multicomponent mixtures.

    PubMed

    Ciccone, Lidia; Tepshi, Livia; Nencetti, Susanna; Stura, Enrico A

    2015-01-25

    Crystallographic structure determination of protein-ligand complexes of transthyretin (TTR) has been hindered by the low affinity of many compounds that bind to the central cavity of the tetramer. Because crystallization trials are carried out at protein and ligand concentration that approach the millimolar range, low affinity is less of a problem than the poor solubility of many compounds that have been shown to inhibit amyloid fibril formation. To achieve complete occupancy in co-crystallization experiments, the minimal requirement is one ligand for each of the two sites within the TTR tetramer. Here we present a new strategy for the co-crystallization of TTR using high molecular weight polyethylene glycol instead of high ionic strength precipitants, with ligands solubilized in multicomponent mixtures of compounds. This strategy is applied to the crystallization of TTR complexes with curcumin and 16α-bromo-estradiol. Here we report the crystal structures with these compounds and with the ferulic acid that results from curcumin degradation.

  12. A structural investigation of ionic liquid mixtures.

    PubMed

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

    2016-03-28

    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 (<50 mol%) of a weakly coordinating anion due to their propensity to form anion-π(+) interactions. These results suggest that the formation of IL mixtures with different anions leads to subtle structural changes of much lower energy than the Coulombic ordering of ions, accounting for why most IL mixtures exhibit ideal, or nearly ideal, behaviour. PMID:26947103

  13. A structural investigation of ionic liquid mixtures.

    PubMed

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

    2016-03-28

    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 (<50 mol%) of a weakly coordinating anion due to their propensity to form anion-π(+) interactions. These results suggest that the formation of IL mixtures with different anions leads to subtle structural changes of much lower energy than the Coulombic ordering of ions, accounting for why most IL mixtures exhibit ideal, or nearly ideal, behaviour.

  14. Non-equilibrium dynamics of glass-forming liquid mixtures

    NASA Astrophysics Data System (ADS)

    Sánchez-Díaz, Luis Enrique; Lázaro-Lázaro, Edilio; Olais-Govea, José Manuel; Medina-Noyola, Magdaleno

    2014-06-01

    The non-equilibrium self-consistent generalized Langevin equation theory of irreversible processes in glass-forming liquids [P. Ramírez-González and M. Medina-Noyola, Phys. Rev. E 82, 061503 (2010)] is extended here to multi-component systems. The resulting theory describes the statistical properties of the instantaneous local particle concentration profiles nα(r, t) of species α in terms of the coupled time-evolution equations for the mean value overline{n}_α ({r},t) and for the covariance σ _{α β }({r},{r}^' };t)equiv overline{δ n_α ({r},t)δ n_β ({r}^' },t)} of the fluctuations δ n_α ({r},t) = n_α ({r},t)- overline{n}_α ({r},t). As in the monocomponent case, these two coarse-grained equations involve a local mobility function bα(r, t) for each species, written in terms of the memory function of the two-time correlation function C_{α β }({r},{r}^' };t,t^' }) equiv overline{δ n_α ({r},t)δ n_β ({r}^' },t^' })}. If the system is constrained to remain spatially uniform and subjected to a non-equilibrium preparation protocol described by a given temperature and composition change program T(t) and overline{n}_α (t), these equations predict the irreversible structural relaxation of the partial static structure factors Sαβ(k; t) and of the (collective and self) intermediate scattering functions Fαβ(k, τ; t) and F^S_{α β }(k,τ ;t). We illustrate the applicability of the resulting theory with two examples involving simple model mixtures subjected to an instantaneous temperature quench: an electroneutral binary mixture of equally sized and oppositely charged hard-spheres, and a binary mixture of soft-spheres of moderate size-asymmetry.

  15. Mathematical Modeling of Non-Stationary Hydraulic Process Occurring in the Gas Centrifuge Cascade During the Separation of Multicomponent Isotope Mixtures

    NASA Astrophysics Data System (ADS)

    Orlov, A. A.; Ushakov, A. A.; Sovach, V. P.

    2016-08-01

    This article presents results of development of the mathematical model of nonstationary separation processes occurring in gas centrifuge cascades for separation of multicomponent isotope mixtures. This model was used for the calculation parameters of gas centrifuge cascade for separation of germanium isotopes. Comparison of obtained values with results of other authors revealed that developed mathematical model is adequate to describe nonstationary separation processes in gas centrifuge cascades for separation of multicomponent isotope mixtures.

  16. CONTAMINANT TRANSPORT RESULTING FROM MULTICOMPONENT NONAQUEOUS PHASE LIQUID POOL DISSOLUTION IN THREE-DIMENSIONAL SUBSURFACE FORMATIONS (R823579)

    EPA Science Inventory

    A semi-analytical method for simulating transient contaminant transport originating from the dissolution of multicomponent nonaqueous phase liquid (NAPL) pools in three-dimensional, saturated, homogeneous porous media is presented. Each dissolved component may undergo first-order...

  17. The Kirkwood-Buff theory of solutions and the local composition of liquid mixtures.

    PubMed

    Shulgin, Ivan L; Ruckenstein, Eli

    2006-06-29

    The present paper is devoted to the local composition of liquid mixtures calculated in the framework of the Kirkwood-Buff theory of solutions. A new method is suggested to calculate the excess (or deficit) number of various molecules around a selected (central) molecule in binary and multicomponent liquid mixtures in terms of measurable macroscopic thermodynamic quantities, such as the derivatives of the chemical potentials with respect to concentrations, the isothermal compressibility, and the partial molar volumes. This method accounts for an inaccessible volume due to the presence of a central molecule and is applied to binary and ternary mixtures. For the ideal binary mixture it is shown that because of the difference in the volumes of the pure components there is an excess (or deficit) number of different molecules around a central molecule. The excess (or deficit) becomes zero when the components of the ideal binary mixture have the same volume. The new method is also applied to methanol + water and 2-propanol + water mixtures. In the case of the 2-propanol + water mixture, the new method, in contrast to the other ones, indicates that clusters dominated by 2-propanol disappear at high alcohol mole fractions, in agreement with experimental observations. Finally, it is shown that the application of the new procedure to the ternary mixture water/protein/cosolvent at infinite dilution of the protein led to almost the same results as the methods involving a reference state.

  18. Investigations into complex liquid crystal mixtures

    NASA Astrophysics Data System (ADS)

    Kirchhoff, Jennifer

    Liquid crystal phases exhibit physical characteristics that lie between those of liquid and crystal phases. The many liquid crystal sub-phases are defined based on the degree of positional and orientational ordering the molecules have and the materials that make up these liquid crystal phases. This thesis presents a study of the molecular packing and physical properties of complex liquid crystal phases using dopants to better examine the stability and packing mechanisms of these phases. It also looks at the dispersion of quantum dots in liquid crystal materials, examining the electro-optical properties of the mixtures. The main goal of this thesis is to examine the effects of dopants on the properties of liquid crystal phases using optical microscopy, differential scanning calorimetry, electro-optical measurements, and X-ray scattering. For those mixtures with quantum dots fluorescence microscopy and photoluminescence measurements were also conducted. Rod-like liquid crystals are commonly used in display applications when the material is in a nematic liquid crystal phase, which is the least ordered phase exhibiting no positional ordering. The more complicated chiral smectic liquid crystal phases, which have a one dimensional layer structure, show potential for faster and tri-stable switching. A chiral rod-like liquid crystal material is doped with both chiral and achiral rod-like liquid crystals to examine the stability of one of the chiral smectic sub-phase, the SmC* FI1 phase. This phase consists of tilted molecules rotating about the cone defined by the tilt angle with a periodicity of three layers and an overall helical structure. The SmC*FI1 phase is stabilized by the competition between antiferroelectric and ferroelectric interactions, and small amounts of the achiral dopant broadens the range of this phase by almost 5°C. Higher dopant concentrations of the achiral material result in the destabilization of not just the SmC*FI1 phase but all tilted sub

  19. DETERMINATION AND QUANTIFICATION OF NON-AQUEOUS PHASE LIQUID MIXTURES IN ENVIRONMENTAL MEDIA

    SciTech Connect

    Rucker, G

    2006-09-22

    It is important to recognize the presence of Non-Aqueous Phase Liquids (NAPLs) in soils at a waste site in order to design and construct a successful remediation system. NAPLs often manifest as a complex, multi-component mixture of organic compounds that can occur in environmental media, such as vadose zone soil, where the mixture will partition and equilibrate with soil particles, pore vapor, and pore water. Complex organic mixtures can greatly complicate the determination and quantification of NAPL in soil due to inter-media transfer. NAPL thresholds can also change because of mixture physical properties and can disguise the presence of NAPL. A unique analytical method and copyrighted software have been developed at the Department of Energy's Savannah River Site that facilitates solution of this problem. The analytical method uses a classic chemistry approach and applies the principals of solubility limit theory, Raoult's Law, and equilibrium chemistry to derive an accurate estimation of NAPL presence and quantity. The method is unique because it calculates an exact result that is mass balanced for each physical state, chemical mixture component, and mixture characteristics. The method is also unique because the solution can be calculated on both a wet weight and dry weight basis--a factor which is often overlooked. The software includes physical parameters for 300 chemicals in a database that self-loads into the model to save time. The method accommodates up to 20 different chemicals in a multi-component mixture analysis. A robust data display is generated including important parameters of the components and mixture including: NAPL thresholds for individual chemical components within the mixture, mass distribution in soil for each physical state, molar fractions, density, vapor pressure, solubility, mass balance, media concentrations, residual saturation, and modest graphing capabilities. This method and software are power tools to simplify otherwise tedious

  20. Enantiomer-specific analysis of multi-component mixtures by correlated electron imaging–ion mass spectrometry

    PubMed Central

    Fanood, Mohammad M Rafiee; Ram, N. Bhargava; Lehmann, C. Stefan; Powis, Ivan; Janssen, Maurice H. M.

    2015-01-01

    Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Here we show how enantiomers may be differentiated by mass-selected photoelectron circular dichroism using an electron–ion coincidence imaging spectrometer. As proof of concept, vapours containing ∼1% of two chiral monoterpene molecules, limonene and camphor, are irradiated by a circularly polarized femtosecond laser, resulting in multiphoton near-threshold ionization with little molecular fragmentation. Large chiral asymmetries (2–4%) are observed in the mass-tagged photoelectron angular distributions. These asymmetries switch sign according to the handedness (R- or S-) of the enantiomer in the mixture and scale with enantiomeric excess of a component. The results demonstrate that mass spectrometric identification of mixtures of chiral molecules and quantitative determination of enantiomeric excess can be achieved in a table-top instrument. PMID:26104140

  1. Enantiomer-specific analysis of multi-component mixtures by correlated electron imaging-ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Fanood, Mohammad M. Rafiee; Ram, N. Bhargava; Lehmann, C. Stefan; Powis, Ivan; Janssen, Maurice H. M.

    2015-06-01

    Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Here we show how enantiomers may be differentiated by mass-selected photoelectron circular dichroism using an electron-ion coincidence imaging spectrometer. As proof of concept, vapours containing ~1% of two chiral monoterpene molecules, limonene and camphor, are irradiated by a circularly polarized femtosecond laser, resulting in multiphoton near-threshold ionization with little molecular fragmentation. Large chiral asymmetries (2-4%) are observed in the mass-tagged photoelectron angular distributions. These asymmetries switch sign according to the handedness (R- or S-) of the enantiomer in the mixture and scale with enantiomeric excess of a component. The results demonstrate that mass spectrometric identification of mixtures of chiral molecules and quantitative determination of enantiomeric excess can be achieved in a table-top instrument.

  2. Percolation segregation in multi-size and multi-component particulate mixtures: Measurement, sampling, and modeling

    NASA Astrophysics Data System (ADS)

    Jha, Anjani K.

    Particulate materials are routinely handled in large quantities by industries such as, agriculture, electronic, ceramic, chemical, cosmetic, fertilizer, food, nutraceutical, pharmaceutical, power, and powder metallurgy. These industries encounter segregation due to the difference in physical and mechanical properties of particulates. The general goal of this research was to study percolation segregation in multi-size and multi-component particulate mixtures, especially measurement, sampling, and modeling. A second generation primary segregation shear cell (PSSC-II), an industrial vibrator, a true cubical triaxial tester, and two samplers (triers) were used as primary test apparatuses for quantifying segregation and flowability; furthermore, to understand and propose strategies to mitigate segregation in particulates. Toward this end, percolation segregation in binary, ternary, and quaternary size mixtures for two particulate types: urea (spherical) and potash (angular) were studied. Three coarse size ranges 3,350-4,000 mum (mean size = 3,675 mum), 2,800-3,350 mum (3,075 mum), and 2,360-2,800 mum (2,580 mum) and three fines size ranges 2,000-2,360 mum (2,180 mum), 1,700-2,000 mum (1,850 mum), and 1,400-1,700 mum (1,550 mum) for angular-shaped and spherical-shaped were selected for tests. Since the fines size 1,550 mum of urea was not available in sufficient quantity; therefore, it was not included in tests. Percolation segregation in fertilizer bags was tested also at two vibration frequencies of 5 Hz and 7Hz. The segregation and flowability of binary mixtures of urea under three equilibrium relative humidities (40%, 50%, and 60%) were also tested. Furthermore, solid fertilizer sampling was performed to compare samples obtained from triers of opening widths 12.7 mm and 19.1 mm and to determine size segregation in blend fertilizers. Based on experimental results, the normalized segregation rate (NSR) of binary mixtures was dependent on size ratio, mixing ratio

  3. Investigations into complex liquid crystal mixtures

    NASA Astrophysics Data System (ADS)

    Kirchhoff, Jennifer

    Liquid crystal phases exhibit physical characteristics that lie between those of liquid and crystal phases. The many liquid crystal sub-phases are defined based on the degree of positional and orientational ordering the molecules have and the materials that make up these liquid crystal phases. This thesis presents a study of the molecular packing and physical properties of complex liquid crystal phases using dopants to better examine the stability and packing mechanisms of these phases. It also looks at the dispersion of quantum dots in liquid crystal materials, examining the electro-optical properties of the mixtures. The main goal of this thesis is to examine the effects of dopants on the properties of liquid crystal phases using optical microscopy, differential scanning calorimetry, electro-optical measurements, and X-ray scattering. For those mixtures with quantum dots fluorescence microscopy and photoluminescence measurements were also conducted. Rod-like liquid crystals are commonly used in display applications when the material is in a nematic liquid crystal phase, which is the least ordered phase exhibiting no positional ordering. The more complicated chiral smectic liquid crystal phases, which have a one dimensional layer structure, show potential for faster and tri-stable switching. A chiral rod-like liquid crystal material is doped with both chiral and achiral rod-like liquid crystals to examine the stability of one of the chiral smectic sub-phase, the SmC* FI1 phase. This phase consists of tilted molecules rotating about the cone defined by the tilt angle with a periodicity of three layers and an overall helical structure. The SmC*FI1 phase is stabilized by the competition between antiferroelectric and ferroelectric interactions, and small amounts of the achiral dopant broadens the range of this phase by almost 5°C. Higher dopant concentrations of the achiral material result in the destabilization of not just the SmC*FI1 phase but all tilted sub

  4. Production of liquid hydrocarbon and ether mixtures

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1989-05-16

    An integrated process is described for the production of ether-rich liquid fuels, comprising: (a) etherifying a mixture of excess lower alkyl alcohol and aliphatic hydrocarbon feedstock rich in C/sub 4/+isoalkenes in the presence of acid etherification catalyst whereby lower alkyl tertiary alkyl ethers are produced; (b) separating etherification effluent from step(a) to provide a gasoline stream rich in C/sub 5/+ ethers and a stream comprising unreacted alcohol and alkenes; (c) contacting the unreacted alcohol and alkenes with an acidic metallosilicate zeolite conversion catalyst under olefinic and oxygenates conversion conditions at a temperature of at least 200/sup 0/C (392/sup 0/F) whereby a conversion effluent stream rich in C/sub 4/+ isoalkenes is produced; (d) recycling at least a portion of the conversion effluent stream to step (a) for etherification.

  5. Sound speed measurements in liquid oxygen-liquid nitrogen mixtures

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Mazel, D. S.

    1985-01-01

    The sound speed in liquid oxygen (LOX), liquid nitrogen (LN2), and five LOX-LN2 mixtures was measured by an ultrasonic pulse-echo technique at temperatures in the vicinity of -195.8C, the boiling point of N2 at a pressure of I atm. Under these conditions, the measurements yield the following relationship between sound speed in meters per second and LN2 content M in mole percent: c = 1009.05-1.8275M+0.0026507 M squared. The second speeds of 1009.05 m/sec plus or minus 0.25 percent for pure LOX and 852.8 m/sec plus or minus 0.32 percent for pure LN2 are compared with those reported by past investigators. Measurement of sound speed should prove an effective means for monitoring the contamination of LOX by Ln2.

  6. Eutectic mixtures of ferroelectric liquid crystals

    SciTech Connect

    Goodby, J.W. ); Chin, E. ); Patel, J.S. )

    1989-11-30

    Ferroelectric liquid crystals show potential as the optically and electrically active media in a variety of applications. However, it is considered unlikely that a single individual compound will possess all of the desired properties required by device applications, and therefore it is to be expected that it will be necessary to mix compounds together in order to obtain a suitable blend. In this study we have examined how the pitch of the helix and the magnitude of the spontaneous polarization of the ferroelectric smectic C* phase vary as a function of concentration when two materials of opposite twist and with the same (or opposite) polarization directions are mixed together. In some cases the ferroelectric phase(s) was found to disappear in the central region of the phase diagram, only to be replaced by the nonferroelectric smectic B phase. This type of behavior was found to happen even when the two components were of the same generic family. Changes in phase type were detected optically and also from the switching behavior in individual mixtures. This second approach offers a new method of monitoring certain phase changes that occur in a phase diagram.

  7. Application of isoabsorption plots generated by high-performance liquid chromatography with diode array detection to the development of multicomponent quantitative analysis of traditional herbal medicines.

    PubMed

    Fang, Luo; Yang, Guonong; Song, Yu; Li, Fanzhu; Lin, Nengming

    2014-11-01

    Multicomponent quantitative analysis is one of the mainstream quality control methods of traditional herbal medicines. Since the constituents of traditional herbal medicines samples are complex, the development of high-performance liquid chromatography methods is laborious. In this study, an isoabsorption plot, a chromatographic/spectrometric data image plotted by diode array detection was utilized to facilitate the establishment of a high-performance liquid chromatography method by optimizing and validating the detection conditions off-line. Consequently a simple, reliable and accurate method for simultaneous determination of seven active polyphenolic components (protocatechuic acid, chlorogenic acid, caffeic acid, p-coumaric acid, rosmarinic acid, scutellarin, and apigenin) in Qingfei mixture, a long-used Chinese prescription, was developed. The chromatographic separation was performed on a C18 column with gradient elution of phosphoric acid aqueous solution (0.05%, v/v) and acetonitrile, and a wavelength switch program optimized with isoplot was adopted for detection. The method was validated in terms of linearity, sensitivity, precision, repeatability, and accuracy and was successfully applied to the simultaneous determination of the seven polyphenolic components in different production batches of Qingfei Mixture. These results indicated that isoplot is an effective tool to improve the establishment of multicomponent quantitative analysis methods.

  8. Nucleation in a Sheared Liquid Binary Mixture.

    NASA Astrophysics Data System (ADS)

    Min, Kyung-Yang

    When a binary liquid mixture of lutidine plus water (LW) is quenched to a temperature T and is exposed to a continuous shear rate S, the result is a steady-state droplet distribution. This steady state can be probed by measuring the unscattered intensity I_{f}, or the scattered intensity I_{s}, as a function of delta T and S. In the experiments described here, S is fixed and delta T is varied in a step-wise fashion. The absence of hysteresis was probed in two separate experiments: First, I_{f} was measured as a function of S for a given delta T. Next, I_{f} was measured as a function of delta T for a given S. In either case, the hysteresis associated with the shear-free nucleation is absent. In addition, a flow-history dependent hysteresis was studied. In the 2-dimensional parameter space consisting of S and delta T, the onset of nucleation uniquely determines a cloud point line. A plot of the cloud point line exhibits two segments of different slopes with a cross-over near the temperature corresponding to the Becker-Doring limit. The classical picture of a free energy barrier was reformulated to explain this cross-over behavior. Next, photon correlation spectroscopy was used to study the dependence of the transient nucleation behavior on the initial states. A unique feature of this study is that this initial state can be conveniently adjusted by varying the shear rate S to which the mixture is initially exposed. The shear is then turned off, and the number density N(t), as well as the mean radius of the growing droplets, is monitored as a function of time. It was possible to measure the droplet density at a very early stage of phase separation where the nucleation rate J was close to zero. The measurement reveals that N(t) depends critically on the initial state of the metastable system. When the shear is large enough to rupture the droplets as small as the critical size, N(t) increases very slowly. Measurements of the nucleation rates vs. the square of the

  9. Phase-field modeling of isothermal quasi-incompressible multicomponent liquids

    NASA Astrophysics Data System (ADS)

    Tóth, Gyula I.

    2016-09-01

    In this paper general dynamic equations describing the time evolution of isothermal quasi-incompressible multicomponent liquids are derived in the framework of the classical Ginzburg-Landau theory of first order phase transformations. Based on the fundamental equations of continuum mechanics, a general convection-diffusion dynamics is set up first for compressible liquids. The constitutive relations for the diffusion fluxes and the capillary stress are determined in the framework of gradient theories. Next the general definition of incompressibility is given, which is taken into account in the derivation by using the Lagrange multiplier method. To validate the theory, the dynamic equations are solved numerically for the quaternary quasi-incompressible Cahn-Hilliard system. It is demonstrated that variable density (i) has no effect on equilibrium (in case of a suitably constructed free energy functional) and (ii) can influence nonequilibrium pattern formation significantly.

  10. Multicomponent membranes

    DOEpatents

    Kulprathipanja, Santi; Kulkarni, Sudhir S.; Funk, Edward W.

    1988-01-01

    A multicomponent membrane which may be used for separating various components which are present in a fluid feed mixture comprises a mixture of a plasticizer such as a glycol and an organic polymer cast upon a porous organic polymer support. The membrane may be prepared by casting an emulsion or a solution of the plasticizer and polymer on the porous support, evaporating the solvent and recovering the membrane after curing.

  11. Two-fluid theory and thermodynamic properties of liquid mixtures. Application to hard-sphere mixtures

    PubMed Central

    Brandani, V.; Prausnitz, J. M.

    1982-01-01

    This paper is the second of three describing a two-fluid theory of binary liquid mixtures. The general theory presented in the preceding paper is used to derive a model for calculating thermodynamic properties of hard-sphere mixtures. Calculations indicate that desirable boundary conditions are satisfied. PMID:16593220

  12. Perturbation theory for multicomponent fluids based on structural properties of hard-sphere chain mixtures

    NASA Astrophysics Data System (ADS)

    Hlushak, Stepan

    2015-09-01

    An analytical expression for the Laplace transform of the radial distribution function of a mixture of hard-sphere chains of arbitrary segment size and chain length is used to rigorously formulate the first-order Barker-Henderson perturbation theory for the contribution of the segment-segment dispersive interactions into thermodynamics of the Lennard-Jones chain mixtures. Based on this approximation, a simple variant of the statistical associating fluid theory is proposed and used to predict properties of several mixtures of chains of different lengths and segment sizes. The theory treats the dispersive interactions more rigorously than the conventional theories and provides means for more accurate description of dispersive interactions in the mixtures of highly asymmetric components.

  13. Perturbation theory for multicomponent fluids based on structural properties of hard-sphere chain mixtures

    SciTech Connect

    Hlushak, Stepan

    2015-09-28

    An analytical expression for the Laplace transform of the radial distribution function of a mixture of hard-sphere chains of arbitrary segment size and chain length is used to rigorously formulate the first-order Barker-Henderson perturbation theory for the contribution of the segment-segment dispersive interactions into thermodynamics of the Lennard-Jones chain mixtures. Based on this approximation, a simple variant of the statistical associating fluid theory is proposed and used to predict properties of several mixtures of chains of different lengths and segment sizes. The theory treats the dispersive interactions more rigorously than the conventional theories and provides means for more accurate description of dispersive interactions in the mixtures of highly asymmetric components.

  14. `Guest-host' effect in liquid crystal mixtures

    NASA Astrophysics Data System (ADS)

    Suchodolska, B.; Rudzki, A.; Ossowska-Chruściel, M. D.; Zalewski, S.; Chruściel, J.

    2015-01-01

    The most important goal of our research is to show the influence of the 'guest' (bent-core mesogen, 1,3-phenyldicarboxylatebis{4-[(4-octylbenzoyl)sulphanyl]phenyl} [IFOS8], banana-shaped liquid crystal [BLC]) on the 'host' (calamitic liquid crystal [CLC], (S)-(+)-1-methylheptyloxybiphenyl-(4-n-octylphenyl)thiobenzoate [MHOBS8]), on the stability and the destabilization of the antiferroelectric B2 and the ferroelectric smectic C* (SmC*) phases, and change of the temperature ranges of other phases in the binary liquid crystal mixtures. This work is focused on polymorphism of three new binary liquid crystal mixtures, exhibiting a 'guest-host' (guest liquid crystal-host liquid crystal [GH-LC]) effect. MHOBS8 has, among others, a ferroelectric SmC* phase, and IFOS8 assumes the B2 phase with antiferroelectric properties. The observed properties of the mixtures, such as variation of the phase transition temperatures, spontaneous polarization, tilt angle and switching time, are characteristic of a 'guest-host' mixture. The influence of BLC on the character of the interactions within the CLC host is discussed, with particular attention paid to electro-optical properties of the GH-LC mixtures.

  15. Evaporation of multi-component mixtures and shell formation in spray dried droplets

    NASA Astrophysics Data System (ADS)

    Valente, Pedro; Duarte, Íris; Porfirio, Tiago; Temtem, Márcio

    2015-11-01

    Drug particles where the active pharmaceutical ingredient (APIs) is dispersed in a polymer matrix forming an amorphous solid dispersion (ASD) is a commonly used strategy to increase the solubility and dissolution rate of poorly water soluble APIs. However, the formation and stability of an amorphous solid dispersion depends on the polymer/API combination and process conditions to generate it. The focus of the present work is to further develop a numerical tool to predict the formation of ASDs by spray drying solutions of different polymer/API combinations. Specifically, the evaporation of a multi-component droplet is coupled with a diffusion law within the droplet that minimizes the Gibbs free energy of the polymer/API/solvents system, following the Flory-Huggins model. Prior to the shell formation, the evaporation of the solvents is modelled following the simplified approach proposed by Abramzon & Sirignano (1989) which accounts for the varying relative velocity between the droplet and the drying gas. After shell formation, the diffusion of the solvents across the porous shell starkly modifies the evaporative dynamics.

  16. Low-melting mixtures based on choline ionic liquids.

    PubMed

    Rengstl, Doris; Fischer, Veronika; Kunz, Werner

    2014-11-01

    In this article a strategy is proposed for the design of low toxic, room temperature liquid low-melting mixtures (LMMs) which are entirely composed of natural materials. From literature it is well known that, in general, deep eutectic solvents based on choline chloride and dicarboxylic acids are LMMs, but not liquids at room temperature, with one exception: a 1 : 1 molar mixture of malonic acid and choline chloride. Therefore, the starting point of this study was the decrease of the melting point of one of the components, namely the dicarboxylic acid, which is succinic, glutaric or adipic acid. For this purpose, one of the two protons of the acidic group was exchanged by a bulky unsymmetrical choline cation. The resulting ionic liquids (ILs) were still solid at room temperature, but have a reduced melting temperature compared to the corresponding acids. In the second step, mixtures of these ILs with choline chloride were prepared. It turned out that choline glutarate-choline chloride mixtures are liquids at room temperature at compositions containing 95-98 wt% of choline glutarate. Finally, urea was added as another hydrogen bond donor. Density, conductivity and viscosity measurements were performed for all obtained mixtures. Moreover, a Walden plot was drawn which indicates that all mixtures are liquids with fully dissociated ions moving independently. Therefore, they are considered as "good" ionic liquids and, thus, for example they can be used to exchange more toxic or less biodegradable ILs in application processes. A brief outlook containing application possibilities is given. It is demonstrated that choline dodecylsulfate is readily soluble in these mixtures, forming aggregates in the LMM at temperatures exceeding 55 °C.

  17. Low-melting mixtures based on choline ionic liquids.

    PubMed

    Rengstl, Doris; Fischer, Veronika; Kunz, Werner

    2014-11-01

    In this article a strategy is proposed for the design of low toxic, room temperature liquid low-melting mixtures (LMMs) which are entirely composed of natural materials. From literature it is well known that, in general, deep eutectic solvents based on choline chloride and dicarboxylic acids are LMMs, but not liquids at room temperature, with one exception: a 1 : 1 molar mixture of malonic acid and choline chloride. Therefore, the starting point of this study was the decrease of the melting point of one of the components, namely the dicarboxylic acid, which is succinic, glutaric or adipic acid. For this purpose, one of the two protons of the acidic group was exchanged by a bulky unsymmetrical choline cation. The resulting ionic liquids (ILs) were still solid at room temperature, but have a reduced melting temperature compared to the corresponding acids. In the second step, mixtures of these ILs with choline chloride were prepared. It turned out that choline glutarate-choline chloride mixtures are liquids at room temperature at compositions containing 95-98 wt% of choline glutarate. Finally, urea was added as another hydrogen bond donor. Density, conductivity and viscosity measurements were performed for all obtained mixtures. Moreover, a Walden plot was drawn which indicates that all mixtures are liquids with fully dissociated ions moving independently. Therefore, they are considered as "good" ionic liquids and, thus, for example they can be used to exchange more toxic or less biodegradable ILs in application processes. A brief outlook containing application possibilities is given. It is demonstrated that choline dodecylsulfate is readily soluble in these mixtures, forming aggregates in the LMM at temperatures exceeding 55 °C. PMID:25242504

  18. Evaporation of Ethanol-Water Binary Mixture Sessile Liquid Marbles.

    PubMed

    Ooi, Chin Hong; Bormashenko, Edward; Nguyen, Anh V; Evans, Geoffrey M; Dao, Dzung V; Nguyen, Nam-Trung

    2016-06-21

    Liquid marble is a liquid droplet coated with particles. Recently, the evaporation process of a sessile liquid marble using geometric measurements has attracted great attention from the research community. However, the lack of gravimetric measurement limits further insights into the physical changes of a liquid marble during the evaporation process. Moreover, the evaporation process of a marble containing a liquid binary mixture has not been reported before. The present paper investigates the effective density and the effective surface tension of an evaporating liquid marble that contains aqueous ethanol at relatively low concentrations. The effective density of an evaporating liquid marble is determined from the concurrent measurement of instantaneous mass and volume. Density measurements combined with surface profile fitting provide the effective surface tension of the marble. We found that the density and surface tension of an evaporating marble are significantly affected by the particle coating. PMID:27230102

  19. Evaporation of Ethanol-Water Binary Mixture Sessile Liquid Marbles.

    PubMed

    Ooi, Chin Hong; Bormashenko, Edward; Nguyen, Anh V; Evans, Geoffrey M; Dao, Dzung V; Nguyen, Nam-Trung

    2016-06-21

    Liquid marble is a liquid droplet coated with particles. Recently, the evaporation process of a sessile liquid marble using geometric measurements has attracted great attention from the research community. However, the lack of gravimetric measurement limits further insights into the physical changes of a liquid marble during the evaporation process. Moreover, the evaporation process of a marble containing a liquid binary mixture has not been reported before. The present paper investigates the effective density and the effective surface tension of an evaporating liquid marble that contains aqueous ethanol at relatively low concentrations. The effective density of an evaporating liquid marble is determined from the concurrent measurement of instantaneous mass and volume. Density measurements combined with surface profile fitting provide the effective surface tension of the marble. We found that the density and surface tension of an evaporating marble are significantly affected by the particle coating.

  20. Viscosity of Liquid Crystal Mixtures in the Presence of Electroconvection

    NASA Astrophysics Data System (ADS)

    Nagaya, Tomoyuki; Satou, Yuki; Goto, Yoshitomo; Hidaka, Yoshiki; Orihara, Hiroshi

    2016-07-01

    We have experimentally investigated the viscosity of nematic liquid crystal mixtures of p-methoxybenzylidene-p'-n-butylaniline (MBBA) and p-ethoxybenzylidene-p'-cyanoaniline (EBCA) in the presence of electroconvection under an ac electric field with 60 Hz. Although the viscosity of the mixtures with negative dielectric anisotropy shows a characteristic decrease in the high-voltage regime, that with positive dielectric anisotropy shows a monotonic increase as the applied voltage is increased. The experimental results suggest that the decrease in viscosity observed only for the mixtures with negative dielectric anisotropy is attributed to the negative contribution of electric stress caused by the anisotropic director distribution of the turbulent state.

  1. Dielectric constant of liquid alkanes and hydrocarbon mixtures

    NASA Technical Reports Server (NTRS)

    Sen, A. D.; Anicich, V. G.; Arakelian, T.

    1992-01-01

    The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

  2. Dielectric constant of liquid alkanes and hydrocarbon mixtures.

    PubMed

    Sen, A D; Anicich, V G; Arakelian, T

    1992-01-01

    The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

  3. Adsorption at the liquid-vapor surface of a binary liquid mixture

    NASA Astrophysics Data System (ADS)

    Whitmer, J. K.; Kiselev, S. B.; Law, B. M.

    2005-11-01

    In a binary liquid mixture, the component possessing the lowest surface tension preferentially adsorbs at the liquid-vapor surface. In the past this adsorption behavior has been extensively investigated for critical binary liquid mixtures near the mixture's critical temperature Tc. In this fluctuation-dominated regime the adsorption is described by a universal function of the dimensionless depth z /ξ where ξ is the bulk correlation length. Fewer studies have quantitatively examined adsorption for off-critical mixtures because, in this case, one must carefully account for both the bulk and surface crossover from the fluctuation-dominated regime (close to Tc) to the mean-field dominated regime (far from Tc). In this paper we compare extensive liquid-vapor ellipsometric adsorption measurements for the mixture aniline+cyclohexane at a variety of critical and noncritical compositions with the crossover theory of Kiselev and co-workers [J. Chem. Phys. 112, 3370 (2000)].

  4. Relative quantification of multi-components in Panax notoginseng (Sanqi) by high-performance liquid chromatography with mass spectrometry using mobile phase compensation.

    PubMed

    Lai, Chang-jiang-sheng; Tan, Ting; Zeng, Su-ling; Dong, Xin; Liu, E-Hu; Li, Ping

    2015-01-01

    Relative quantification of multi-components in complex mixture is significantly affected by the ionization variance caused by mobile phase composition in high-performance liquid chromatography with electrospray ionization mass spectrometry (HPLC-ESI-MS) analyses. The normalization methods for eliminating the variance are still less investigated. Herein, the mobile-phase compensation (MPC) method was applied to overcome the above problem. The developed method was firstly used for convenient evaluation of the coeluent interference and subsequently applied for relative quantification of the identified multi-components in Panax notoginseng (Sanqi) samples. The good linearity, precision and low limit of quantification of targeted analytes confirmed that the MPC-HPLC-ESI-MS method in gradient elution could achieve the isocratic test results compared with classical HPLC-ESI-MS. The established method was used for relative quantification of the minor Sanqi saponins by their detected peak areas divided by that of ginsenoside Rd. The results demonstrated the potential of the newly developed method for obtaining the normalized data shared in different laboratories.

  5. Electron avalanches in liquid argon mixtures

    SciTech Connect

    Kim, J.G.; Dardin, S.M.; Kadel, R.W.; Kadyk, J.A.; Wenzel, W.B.; Peskov, V.

    2004-03-19

    We have observed stable avalanche gain in liquid argon when mixed with small amounts of xenon in the high electric field (>7 MV/cm) near the point of a chemically etched needle in a point-plane geometry. We identify two gain mechanisms, one pressure dependent, and the other independent of the applied pressure. We conclude that the pressure dependent signals are from avalanche gain in gas bubbles at the tip of the needle, while the pressure independent pulses are from avalanche gain in liquid. We measure the decay time spectra of photons from both types of avalanches. The decay times from the pressure dependent pulses decrease (increase) with the applied pressure (high voltage), while the decay times from the pressure independent pulses are approximately independent of pressure or high voltage. For our operating conditions, the collected charge distribution from avalanches is similar for 60 keV or 122 keV photon sources. With krypton additives, instead of Xe, we measure behavior consistent with only the pressure dependent pulses. Neon and TMS were also investigated as additives, and designs for practical detectors were tested.

  6. Ultrasonic study on organic liquid and binary organic liquid mixtures by using Schaaffs' collision factor theory

    NASA Astrophysics Data System (ADS)

    Lu, Yi-Gang; Dong, Yan-Wu

    2006-09-01

    Based on Schaaffs' collision factor theory (CFT) in liquids, the equations for nonlinear ultrasonic parameters in both organic liquid and binary organic liquid mixtures are deduced. The nonlinear ultrasonic parameters, including pressure coefficient, temperature coefficients of ultrasonic velocity, and nonlinear acoustic parameter B/A in both organic liquid and binary organic liquid mixtures, are evaluated for comparison with the measured results and data from other sources. The equations show that the coefficient of ultrasonic velocity and nonlinear acoustic parameter B/A are closely related to molecular interactions. These nonlinear ultrasonic parameters reflect some information of internal structure and outside status of the medium or mixtures. From the exponent of repulsive forces of the molecules, several thermodynamic parameters, pressure and temperature of the medium, the nonlinear ultrasonic parameters and ultrasonic nature of the medium can be evaluated. When evaluating and studying nonlinear acoustic parameter B/A of binary organic liquid mixtures, there is no need to know the nonlinear acoustic parameter B/A of the components. Obviously, the equation reveals the connection between the nonlinear ultrasonic nature and internal structure and outside status of the mixtures more directly and distinctly than traditional mixture law for B/A, e.g. Apfel's and Sehgal's laws for liquid binary mixtures.

  7. Composition dependent structural organization in trihexyl(tetradecyl)phosphonium chloride ionic liquid-methanol mixtures

    SciTech Connect

    Gupta, Aditya; Sharma, Shobha; Kashyap, Hemant K.

    2015-04-07

    This article reports results from the molecular dynamics simulations on the structural arrangement of the ions and molecules in the mixtures of trihexyl(tetradecyl)phosphonium chloride ([P{sub 666,14}{sup +}][Cl{sup −}]) ionic liquid (IL) and methanol (MeOH) over the entire composition range. Effects of composition on the charge and polarity orderings have been investigated via computation of X-ray scattering structure function, S(q), and by using a partitioning scheme proposed for such multi-component mixtures. Except for the neat methanol liquid, the total S(q) shows two peaks in its intermolecular region for all the mole-fractions. The lowest q peak is dominated primarily by anion-anion, cation-anion, and methanol-anion correlations. Our results signify that the methanol bulk structure, which predominantly has short-distance characteristic correlations and is governed by polar group of methanol, is retained for x{sub IL} ≤ 0.1. Then, the mixture goes through gradual structural changes from methanol-like to the IL-like for 0.1 < x{sub IL} ≤ 0.7. The dipolar interaction between methanol molecules weakens in this range, and the structural landscape of the mixture is steered by strong ion-ion, anion-methanol, and nonpolar interactions. The IL-like structural arrangement is virtually recovered for x{sub IL} > 0.7. At all the compositions studied, while the cation head groups are predominantly solvated by anions and subsequently by methanol molecules, the polar hydroxyl group of methanol is preferentially solvated by the anions. The radial distribution functions of selected pair of atomic species have also confirmed these observations.

  8. Method for removing organic liquids from aqueous solutions and mixtures

    DOEpatents

    Hrubesh, Lawrence W.; Coronado, Paul R.; Dow, Jerome P.

    2004-03-23

    A method for removing organic liquids from aqueous solutions and mixtures. The method employs any porous material preferably in granular form and having small pores and a large specific surface area, that is hydrophobic so that liquid water does not readily wet its surface. In this method, organics, especially organic solvents that mix with and are more volatile than water, are separated from aqueous solution by preferentially evaporating across the liquid/solid boundary formed at the surfaces of the hydrophobic porous materials. Also, organic solvents that are immiscible with water, preferentially wet the surfaces of the hydrophobic material and are drawn within the porous materials by capillary action.

  9. Binary Mixtures of Calamitic and Discotic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Martin, Joshua S.; Garg, Shila

    2002-03-01

    It has been suggested that the elusive biaxial nematic phase could be achieved by a suitable mixture of discotic and calamitic liquid crystals [1]. We propose to investigate the miscibility and phase diagram of such a mixture. For this study, the rod-like molecule is chosen to be the commercially purchased p-hexyloxy benzoic acid. The disk-like molecule is triarylamino-1,3,5-triazine [2] and is synthesized by us. Physical characteristics of this mixture will be studied with the primary objective being the phase properties. Measurements of elastic properties of p-hexyloxy benzoic acid will also be presented. [1] G.R. Luckhurst, Thin Solid Films, 393, 40 (2001). [2] D. Goldmann, D. Janietz. R. Festag, C. Schmidt and J. Wendorff, Liquid Crystals, 21, 619 (1996). This research was supported by the Copeland Fund as administered by The College of Wooster.

  10. Low Mach number fluctuating hydrodynamics of multispecies liquid mixtures

    SciTech Connect

    Donev, Aleksandar Bhattacharjee, Amit Kumar; Nonaka, Andy; Bell, John B.; Garcia, Alejandro L.

    2015-03-15

    We develop a low Mach number formulation of the hydrodynamic equations describing transport of mass and momentum in a multispecies mixture of incompressible miscible liquids at specified temperature and pressure, which generalizes our prior work on ideal mixtures of ideal gases [Balakrishnan et al., “Fluctuating hydrodynamics of multispecies nonreactive mixtures,” Phys. Rev. E 89 013017 (2014)] and binary liquid mixtures [Donev et al., “Low mach number fluctuating hydrodynamics of diffusively mixing fluids,” Commun. Appl. Math. Comput. Sci. 9(1), 47-105 (2014)]. In this formulation, we combine and extend a number of existing descriptions of multispecies transport available in the literature. The formulation applies to non-ideal mixtures of arbitrary number of species, without the need to single out a “solvent” species, and includes contributions to the diffusive mass flux due to gradients of composition, temperature, and pressure. Momentum transport and advective mass transport are handled using a low Mach number approach that eliminates fast sound waves (pressure fluctuations) from the full compressible system of equations and leads to a quasi-incompressible formulation. Thermal fluctuations are included in our fluctuating hydrodynamics description following the principles of nonequilibrium thermodynamics. We extend the semi-implicit staggered-grid finite-volume numerical method developed in our prior work on binary liquid mixtures [Nonaka et al., “Low mach number fluctuating hydrodynamics of binary liquid mixtures,” http://arxiv.org/abs/1410.2300 (2015)] and use it to study the development of giant nonequilibrium concentration fluctuations in a ternary mixture subjected to a steady concentration gradient. We also numerically study the development of diffusion-driven gravitational instabilities in a ternary mixture and compare our numerical results to recent experimental measurements [Carballido-Landeira et al., “Mixed-mode instability of a

  11. Phase behaviour and conductivity study on multi-component mixtures for electrodeposition in supercritical fluids.

    PubMed

    Bartlett, Philip N; Cook, David C; George, Michael W; Ke, Jie; Levason, William; Reid, Gillian; Su, Wenta; Zhang, Wenjian

    2010-01-14

    Electrochemistry in supercritical CO(2) (scCO(2)) is difficult because the very low dielectric constant of the fluid restricts the solubility of ionic species and the conductivity of dissolved electrolytes. To overcome this problem to allow us to carry out electrodeposition at macroelectrodes from scCO(2) we have investigated the use of co-solvents and modified electrolyte salts chosen to increase their solubility and dissociation in the supercritical fluid. Here we report results of phase behaviour studies for mixtures of CO(2) with [NBu(n)(4)][BF(4)] and either methanol (CH(3)OH) or acetonitrile (CH(3)CN) as the co-solvent. These show that the solubility of [NBu(n)(4)][BF(4)] is approximately 5 times larger when CH(3)CN is the co-solvent rather than CH(3)OH. Consequently the phase behaviour of the ternary of CO(2)-[NBu(n)(4)][BF(4)]-CH(3)CN was studied in greater detail over a range of compositions. To enhance the conductivity of scCO(2)-CH(3)CN a range of electrolyte salts was synthesised in which the [NBu(n)(4)](+) and/or [BF(4)](-) ion were replaced by different derivatives. Results for the phase behaviour and conductivity of these modified electrolyte salts in scCO(2)-CH(3)CN are reported for several different compositions. We find that increasing the degree of fluorination and size of the ions increases the solubility of the electrolyte salt in scCO(2)-CH(3)CN. Of the 11 electrolytes investigated [NBu(n)(4)][B{3,5-C(6)H(3)(CF(3))(2)}(4)] appears the most suitable for use in scCO(2)-CH(3)CN with a molar conductivity of 22-26 S cm(2) mol(-1) and a maximum measured conductivity of approximately 3 mS cm(-1) for 0.07 M [NBu(n)(4)][B{3,5-C(6)H(3)(CF(3))(2)}(4)] dissolved in scCO(2)-CH(3)CN (molar ratio CH(3)CN : CO(2) approximately 0.12) at 20 MPa and 328.15 K. This is an order of magnitude improvement over similar results for the [NBu(n)(4)][BF(4)] parent. Studies of the conductance as a function of the electrolyte concentration suggest that triple ions make an

  12. Influence of microwave heating on liquid-liquid phase inversion and temperature rates for immiscible mixtures.

    PubMed

    Kennedy, Alvin; Tadesse, Solomon; Nunes, Janine; Reznik, Aron

    2011-01-01

    Time dependencies of component temperatures for mixtures of immiscible liquids during microwave heating were studied for acetonitrile-cyclohexane and water-toluene. For the first time, we report microwave induced liquid-liquid phase inversion for acetonitrile-cyclohexane mixture: acetonitrile layer was initially at the bottom of the mixture, after 10 sec of microwave heating its density decreased and it inverted to the top of the mixture for the remainder of the microwave heating. This phase inversion could not be achieved by conventional radiant heating. The maximum rate of temperature growth for the polar component of the mixtures was 2 - 5 times larger than for the non-polar component. This suggests that microwave energy is absorbed by polar liquids (water or acetonitrile) and heat is transferred into the non-polar liquid (toluene or cyclohexane) in the mixture by conduction (in case of cyclohexane) or conduction and convection (in case of toluene). Comparison between experimental data and semi-empirical mathematical models, proposed in [Kennedy et at., 2009] showed good correlation. Average relative error between theoretical and experimental results did not exceed 7%. These results can be used to model the temperature kinetics of components for other multiphase mixtures.

  13. Ionic liquids for separation of olefin-paraffin mixtures

    DOEpatents

    Dai, Sheng; Luo, Huimin; Huang, Jing-Fang

    2013-09-17

    The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula ##STR00001## wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group --N--SO.sub.2--(CF.sub.2).sub.nCF.sub.3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.

  14. Ionic liquids for separation of olefin-paraffin mixtures

    DOEpatents

    Dai, Sheng; Luo, Huimin; Huang, Jing-Fang

    2014-07-15

    The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula ##STR00001## wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group --N--SO.sub.2--(CF.sub.2).sub.nCF.sub.3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.

  15. Mixtures of amino-acid based ionic liquids and water.

    PubMed

    Chaban, Vitaly V; Fileti, Eudes Eterno

    2015-09-01

    New ionic liquids (ILs) involving increasing numbers of organic and inorganic ions are continuously being reported. We recently developed a new force field; in the present work, we applied that force field to investigate the structural properties of a few novel imidazolium-based ILs in aqueous mixtures via molecular dynamics (MD) simulations. Using cluster analysis, radial distribution functions, and spatial distribution functions, we argue that organic ions (imidazolium, deprotonated alanine, deprotonated methionine, deprotonated tryptophan) are well dispersed in aqueous media, irrespective of the IL content. Aqueous dispersions exhibit desirable properties for chemical engineering. The ILs exist as ion pairs in relatively dilute aqueous mixtures (10 mol%), while more concentrated mixtures feature a certain amount of larger ionic aggregates.

  16. A Robust Computational Method for Coupled Liquid-liquid Phase Separation and Gas-particle Partitioning Predictions of Multicomponent Aerosols

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Di Stefano, A.

    2014-12-01

    Providing efficient and reliable model predictions for the partitioning of atmospheric aerosol components between different phases (gas, liquids, solids) is a challenging problem. The partitioning of water, various semivolatile organic components, inorganic acids, bases, and salts, depends simultaneously on the chemical properties and interaction effects among all constituents of a gas + aerosol system. The effects of hygroscopic particle growth on the water contents and physical states of potentially two or more liquid and/or solid aerosol phases in turn may significantly affect multiphase chemistry, the direct effect of aerosols on climate, and the ability of specific particles to act as cloud condensation or ice nuclei. Considering the presence of a liquid-liquid phase separation in aerosol particles, which typically leads to one phase being enriched in rather hydrophobic compounds and the other phase enriched in water and dissolved electrolytes, adds a high degree of complexity to the goal of predicting the gas-particle partitioning of all components. Coupled gas-particle partitioning and phase separation methods are required to correctly account for the phase behaviour of aerosols exposed to varying environmental conditions, such as changes to relative humidity. We present new theoretical insights and a substantially improved algorithm for the reliable prediction of gas-particle partitioning at thermodynamic equilibrium based on the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. We introduce a new approach for the accurate prediction of the phase distribution of multiple inorganic ions between two liquid phases, constrained by charge balance, and the coupling of the liquid-liquid equilibrium model to a robust gas-particle partitioning algorithm. Such coupled models are useful for exploring the range of environmental conditions leading to complete or incomplete miscibility of aerosol constituents which will affect

  17. Non-equilibrium Thermodynamic Dissolution Theory for Multi-Component Solid/Liquid Surfaces Involving Surface Adsorption and Radiolysis Kinetics

    SciTech Connect

    Stout, R B

    2001-04-01

    A theoretical expression is developed for the dissolution rate response for multi-component radioactive materials that have surface adsorption kinetics and radiolysis kinetics when wetted by a multi-component aqueous solution. An application for this type of dissolution response is the performance evaluation of multi-component spent nuclear fuels (SNFs) for long term interim storage and for geological disposition. Typically, SNF compositions depend on initial composition, uranium oxide and metal alloys being most common, and on reactor burnup which results in a wide range of fission product and actinide concentrations that decay by alpha, beta, and gamma radiation. These compositional/burnup ranges of SNFs, whether placed in interim storage or emplaced in a geologic repository, will potentially be wetted by multi-component aqueous solutions, and these solutions may be further altered by radiolytic aqueous species due to three radiation fields. The solid states of the SNFs are not thermodynamically stable when wetted and will dissolve, with or without radiolysis. The following development of a dissolution theory is based on a non-equilibrium thermodynamic analysis of energy reactions and energy transport across a solid-liquid phase change discontinuity that propagates at a quasi-steady, dissolution velocity. The integral form of the energy balance equation is used for this spatial surface discontinuity analysis. The integral formulation contains internal energy functional of classical thermodynamics for both the SNFs' solid state and surface adsorption species, and the adjacent liquid state, which includes radiolytic chemical species. The steady-state concentrations of radiolytic chemical species are expressed by an approximate analysis of the decay radiation transport equation. For purposes of illustration a modified Temkin adsorption isotherm was assumed for the surface adsorption kinetics on an arbitrary, finite area of the solid-liquid dissolution interface. For

  18. Solid-liquid equilibria of binary mixtures of fluorinated ionic liquids.

    PubMed

    Teles, Ana Rita R; Correia, Helga; Maximo, Guilherme J; Rebelo, Luís P N; Freire, Mara G; Pereiro, Ana B; Coutinho, João A P

    2016-09-28

    Within ionic liquids, fluorinated ionic liquids (FILs) present unique physico-chemical properties and potential applications in several fields. However, the melting point of these neoteric compounds is usually higher due to the presence of fluorine atoms. This drawback may be resolved by, for instance, mixing different FILs to create eutectic mixtures. In this work, binary mixtures of fluoro-containing and fluorinated ionic liquids were considered with the aim of decreasing their melting temperatures as well as understanding and characterizing these mixtures and their phase transitions. Five FILs were selected, allowing the investigation of four binary mixtures, each of them with a common ion. Their solid-liquid and solid-solid equilibria were studied by differential scanning calorimetry and the non-ideality of the mixtures was investigated. Overall, a variety of solid-liquid equilibria with systems exhibiting eutectic behavior, polymorphs with solid-solid phase transitions, and the formation of intermediate compounds and solid solutions were surprisingly found. In addition to these intriguing behaviours, novel FILs with lower melting temperatures were obtained by the formation of binary systems, thus enlarging the application range of FILs at lower temperatures. PMID:27603428

  19. Solid-liquid equilibria of binary mixtures of fluorinated ionic liquids.

    PubMed

    Teles, Ana Rita R; Correia, Helga; Maximo, Guilherme J; Rebelo, Luís P N; Freire, Mara G; Pereiro, Ana B; Coutinho, João A P

    2016-09-28

    Within ionic liquids, fluorinated ionic liquids (FILs) present unique physico-chemical properties and potential applications in several fields. However, the melting point of these neoteric compounds is usually higher due to the presence of fluorine atoms. This drawback may be resolved by, for instance, mixing different FILs to create eutectic mixtures. In this work, binary mixtures of fluoro-containing and fluorinated ionic liquids were considered with the aim of decreasing their melting temperatures as well as understanding and characterizing these mixtures and their phase transitions. Five FILs were selected, allowing the investigation of four binary mixtures, each of them with a common ion. Their solid-liquid and solid-solid equilibria were studied by differential scanning calorimetry and the non-ideality of the mixtures was investigated. Overall, a variety of solid-liquid equilibria with systems exhibiting eutectic behavior, polymorphs with solid-solid phase transitions, and the formation of intermediate compounds and solid solutions were surprisingly found. In addition to these intriguing behaviours, novel FILs with lower melting temperatures were obtained by the formation of binary systems, thus enlarging the application range of FILs at lower temperatures.

  20. Mathematical modeling of planar and spherical vapor-liquid phase interfaces for multicomponent fluids

    NASA Astrophysics Data System (ADS)

    Celný, David; Vinš, Václav; Planková, Barbora; Hrubý, Jan

    2016-03-01

    Development of methods for accurate modeling of phase interfaces is important for understanding various natural processes and for applications in technology such as power production and carbon dioxide separation and storage. In particular, prediction of the course of the non-equilibrium phase transition processes requires knowledge of the properties of the strongly curved phase interfaces of microscopic droplets. In our work, we focus on the spherical vapor-liquid phase interfaces for binary mixtures. We developed a robust computational method to determine the density and concentration profiles. The fundamentals of our approach lie in the Cahn-Hilliard gradient theory, allowing to transcribe the functional formulation into a system of ordinary Euler-Langrange equations. This system is then split and modified into a shape suitable for iterative computation. For this task, we combine the Newton-Raphson and the shooting methods providing a good convergence speed. For the thermodynamic roperties, the PC-SAFT equation of state is used. We determine the density and concentration profiles for spherical phase interfaces at various saturation factors for the binary mixture of CO2 and C9H20. The computed concentration profiles allow to the determine the work of formation and other characteristics of the microscopic droplets.

  1. Improvement in device performance from a mixture of a liquid crystal and photosensitive acrylic prepolymer with the photoinduced vertical alignment method

    NASA Astrophysics Data System (ADS)

    Ho, Czung-Yu; Lin, Fa-Hsin; Tao, Yu-Tai; Lee, Jiunn-Yih

    2011-12-01

    In a multicomponent nematic liquid crystal (NLC) mixture of a liquid crystal (negative-type NLC) and a photosensitive acrylic prepolymer, photopolymerization upon UV irradiation induces the separation of the LC and photosensitive acrylic prepolymer layers, thereby leading to a vertical arrangement of LC molecules. In this study, we propose a simple vertical alignment method for LC molecules, by adding a chiral smectic A (SmA*) liquid crystal having homeotropic texture characteristics to an NLC mixture solution. Measurements of electro-optical properties revealed that the addition of the SmA* LC not only strengthened the anchoring force of the copolymer alignment film surface, but also significantly enhanced the contrast ratio (~73%), response time and grayscale switching performance of the device.

  2. Fractionation in Gay-Berne liquid crystal mixtures.

    PubMed

    Moreno-Razo, J Antonio; Díaz-Herrera, Enrique; Klapp, Sabine H L

    2007-10-01

    We present a constant-pressure molecular dynamics simulation study of the phase behavior of binary (50:50) Gay-Berne liquid crystal mixtures consisting of elongated particles with different lengths (LA>LB) and equal diameters. We focus on systems at dense liquid-state conditions. Considering three mixtures characterized by different values of LA(B) and different length ratios q=LB/LA<1, we find complex fluid-fluid phase behavior resulting from the interplay between nematic, smectic-A-type, or smectic-B-type orientational ordering, on the one hand, and demixing into two phases of different composition (fractionation), on the other hand. The driving "forces" of demixing transitions are the temperature and the length ratio. Indeed, in the system characterized by the largest value of q (q=0.86) orientational order occurs already in mixed states, whereas full fractionation is found at q=0.71. The two resulting states are either of type smectic-B-nematic (intermediate temperatures) or smectic-B-smectic-B (low temperatures). In the intermediate case q=0.80 we observe a stepwise ordering and demixing behavior on cooling the system from high temperatures. Moreover, our results show that the stability range of (partially) nematic structures in mixtures of sufficiently small q can be significantly larger than in the pure counterparts, in qualitative agreement with experimental observations.

  3. Induced smectic phases of stoichiometric liquid crystal mixtures.

    PubMed

    Sugisawa, Shin-Ya; Tabe, Yuka

    2016-03-28

    We revealed the detailed structures of induced smectic liquid crystal (LC) phases composed of a binary mixture of charge-transfer (CT) LC substances. Although neither of the constituents had highly ordered smectic phases, the mixture exhibited smectic-E (SmE) or smectic-B (SmB) phases when mixed at ratios of 1 : 1 and 2 : 3, respectively. The results of polarized optical microscopy, differential scanning calorimetry, X-ray diffraction, and infrared spectroscopy indicated that the induced smectic phases were stabilized by an exquisite balance between the CT interactions, dipolar interactions, and excluded volume effects. We proposed a possible model for the molecular arrangements in the SmE and SmB phases, which consistently explained the experimental results including the stoichiometric ratios.

  4. Liquid crystalline state of some fatty acids and mixtures

    NASA Astrophysics Data System (ADS)

    Ghelmez, Mihaela A.; Honciuc, Maria; Piscureanu, Mihai C.

    1998-09-01

    The role of the fatty acids in the biological membrane structure and properties is partially known. They can exhibit a mesogenic feature and behavior in terms of the temperature, the presence of many acids of cholesterol, or other important substances for the metabolism, of external stimuli etc. We studied the arachidic, lauric, elaidic, arachidonic and butiric acids. The most important seems to be the arachidonic acid, a forerunner of phospholipids. This is an unsaturated fatty acid,with four double bounds. We found that it displayed liquid crystalline properties between 4-20 grades centrigrades; in mixture with other fatty acids or cholesterol, these properties change. The paper present considerations on the biological role of the fatty acids and mixtures, in interactions with some physical fields experimental results and some theoretical considerations.

  5. Optical cell with periodic resistive heating for the measurement of heat, mass, and thermal diffusions in liquid mixtures.

    PubMed

    Hartung, M; Köhler, W

    2007-08-01

    A new technique for the measurement of heat, mass, and thermal diffusions in liquids has been developed. Similar to laser induced dynamic gratings, a temperature grating is created in the sample. Thermal expansion transforms the temperature into a refractive-index grating, which is read by diffraction of a readout laser beam. In a multicomponent mixture an additional concentration grating is formed by thermal diffusion driven by the temperature gradients of the temperature grating. Differently to laser induced dynamic grating experiments we use Joule heating instead of optical heating. For that purpose we have built cuvettes which have a grating of transparent conducting strips on the inner side of one of their windows. If heated by an electric current a temperature grating will build up in the sample. Both the heat equation and the extended diffusion equation have been solved in two dimensions to allow for quantitative data analysis. Our apparatus and method of analysis have been validated by measurements of heat, mass, and thermal diffusions in pure and binary liquids. Heat diffusion can be correctly determined as was shown for pure toluene, pure dodecane, and the symmetric mixture of isobutylbenzene dodecane. Mass and thermal diffusions were studied in the three symmetric mixtures of dodecane, isobutylbenzene, and tetralin. The obtained diffusion and Soret coefficients agree with the literature values within the experimental errors. Uncompensated transient heating effects limit the resolution of the experimental technique.

  6. Critical adsorption and colloidal interaction in binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Alam, Sharmine; Omari, Rami; Grabowski, Christopher; Mukhopadhyay, Ashis

    2015-03-01

    We studied critical adsorption on colloidal nanoparticles in binary liquid mixture of 2,6 lutidine + water by using fluorescence correlation spectroscopy (FCS). Our results indicated that the adsorbed film thickness is of the order of correlation length associated with concentration fluctuations. The excess adsorption per unit area increases following a power law in reduced temperature with an exponent of -1, which is the mean-field value for the bulk susceptibility exponent. The measurements at higher particle volume fractions, where particle-particle interaction becomes important, will be presented. Acknowledgements are made to the Donors of the American Chemical Society Petroleum Research fund (PRF # 51694-ND10) for support of this research.

  7. Mixing Enthalpy for Binary Mixtures Containing Ionic Liquids.

    PubMed

    Podgoršek, A; Jacquemin, J; Pádua, A A H; Costa Gomes, M F

    2016-05-25

    A complete review of the published data on the mixing enthalpies of mixtures containing ionic liquids, measured directly using calorimetric techniques, is presented in this paper. The field of ionic liquids is very active and a number of research groups in the world are dealing with different applications of these fluids in the fields of chemistry, chemical engineering, energy, gas storage and separation or materials science. In all these fields, the knowledge of the energetics of mixing is capital both to understand the interactions between these fluids and the different substrates and also to establish the energy and environmental cost of possible applications. Due to the relative novelty of the field, the published data is sometimes controversial and recent reviews are fragmentary and do not represent a set of reliable data. This fact can be attributed to different reasons: (i) difficulties in controlling the purity and stability of the ionic liquid samples; (ii) availability of accurate experimental techniques, appropriate for the measurement of viscous, charged, complex fluids; and (iii) choice of an appropriate clear thermodynamic formalism to be used by an interdisciplinary scientific community. In this paper, we address all these points and propose a critical review of the published data, advise on the most appropriate apparatus and experimental procedure to measure this type of physical-chemical data in ionic liquids as well as the way to treat the information obtained by an appropriate thermodynamic formalism.

  8. The Soret Effect in Liquid Mixtures - A Review

    NASA Astrophysics Data System (ADS)

    Köhler, Werner; Morozov, Konstantin I.

    2016-07-01

    The Soret effect describes diffusive motion that originates from a temperature gradient. It is observed in mixtures of gases, liquids and even solids. Although there is a formal phenomenological description based on linear nonequilibrium thermodynamics, the Soret effect is a multicause phenomenon and there is no univocal microscopic picture. After a brief historical overview and an outline of the fundamental thermodynamic concepts, this review focuses on thermodiffusion in binary and ternary liquid mixtures. The most important experimental techniques used nowadays are introduced. Then, a modern development in studying thermal diffusion, the discovery of both integral and specific additivity laws, is discussed. The former relate to the general behavior of the substances in a temperature field according to their thermophobicities, which prove to be pure component properties. The thermophobicities allow for a convenient classification of the phenomenon, a simple interpretation and a proper estimation and prediction of the thermodiffusion parameters. The specific laws relate to the additivity of the particular contributions. Among the latter, we discuss the isotopic Soret effect and the so-called chemical contribution. From the theoretical side, there are kinetic and thermodynamic theories, and the nature of the driving forces of thermodiffusion can be either of volume or surface type. Besides analytical models, computer simulations become increasingly important. Polymer solutions are special as they represent highly asymmetric molecular systems with a molar mass-independent thermophoretic mobility. Its origin is still under debate, and draining and non-draining models are presently discussed. Finally, some discussion is devoted to ternary mixtures, which only recently have been investigated in more detail.

  9. Ion Partitioning at the liquid/vapor interface of a multi-component alkali halidesolution: A model for aqueous sea salt aerosols

    SciTech Connect

    Ghosal, Sutapa; Brown, Matthew A.; Bluhm, Hendrik; Krisch, Maria J.; Salmeron, Miquel; Jungwirth, Pavel; Hemminger, John C.

    2008-12-22

    The chemistry of Br species associated with sea salt ice and aerosols has been implicated in the episodes of ozone depletion reported at Arctic sunrise. However, Br{sup -} is only a minor component in sea salt, which has a Br{sup -}/Cl{sup -} molar ratio of {approx}0.0015. Sea salt is a complex mixture of many different species, with NaCl as the primary component. In recent years experimental and theoretical studies have reported enhancement of the large, more polarizable halide ion at the liquid/vapor interface of corresponding aqueous alkali halide solutions. The proposed enhancement is likely to influence the availability of sea salt Br{sup -} for heterogeneous reactions such as those involved in the ozone depletion episodes. We report here ambient pressure x-ray photoelectron spectroscopy studies and molecular dynamics simulations showing direct evidence of Br{sup -} enhancement at the interface of an aqueous NaCl solution doped with bromide. The experiments were carried out on samples with Br{sup -}/Cl{sup -} ratios in the range 0.1% to 10%, the latter being also the ratio for which simulations were carried out. This is the first direct measurement of interfacial enhancement of Br{sup -} in a multi-component solution with particular relevance to sea salt chemistry.

  10. Multiphase, multicomponent parameter estimation for liquid and vapor fluxes in deep arid systems using hydrologic data and natural environmental tracers

    USGS Publications Warehouse

    Kwicklis, E.M.; Wolfsberg, A.V.; Stauffer, P.H.; Walvoord, M.A.; Sully, M.J.

    2006-01-01

    Multiphase, multicomponent numerical models of long-term unsaturated-zone liquid and vapor movement were created for a thick alluvial basin at the Nevada Test Site to predict present-day liquid and vapor fluxes. The numerical models are based on recently developed conceptual models of unsaturated-zone moisture movement in thick alluvium that explain present-day water potential and tracer profiles in terms of major climate and vegetation transitions that have occurred during the past 10 000 yr or more. The numerical models were calibrated using borehole hydrologic and environmental tracer data available from a low-level radioactive waste management site located in a former nuclear weapons testing area. The environmental tracer data used in the model calibration includes tracers that migrate in both the liquid and vapor phases (??D, ??18O) and tracers that migrate solely as dissolved solutes (Cl), thus enabling the estimation of some gas-phase as well as liquid-phase transport parameters. Parameter uncertainties and correlations identified during model calibration were used to generate parameter combinations for a set of Monte Carlo simulations to more fully characterize the uncertainty in liquid and vapor fluxes. The calculated background liquid and vapor fluxes decrease as the estimated time since the transition to the present-day arid climate increases. However, on the whole, the estimated fluxes display relatively little variability because correlations among parameters tend to create parameter sets for which changes in some parameters offset the effects of others in the set. Independent estimates on the timing since the climate transition established from packrat midden data were essential for constraining the model calibration results. The study demonstrates the utility of environmental tracer data in developing numerical models of liquid- and gas-phase moisture movement and the importance of considering parameter correlations when using Monte Carlo analysis to

  11. Dielectric properties of antiferroelectric liquid-crystalline mixtures

    NASA Astrophysics Data System (ADS)

    Goc, F.; Kuczynski, Wojciech; Malecki, J.; Dabrowski, Roman S.; Hoffmann, Jerzy

    1999-12-01

    Antiferroelectric liquid crystalline mixtures having smectic CA* phase in very broad temperature range have been investigated. Measurements of dielectric relaxation and spontaneous polarization were performed. Two absorption peaks in the existence range of the antiferroelectric CA* phase in the kHz-MHz range of frequency were observed. Both peaks are quite weak and of Debye type. Their characteristic dielectric strengths are almost temperature independent. The peaks are probably related to the motions of molecules on the side of a cone, defined by the molecule tilt angle, the slower process is related to the motions of molecules, tilted in opposite directions in subsequent layers and moving in the same direction. The process with shorter relaxation time is attributed to the movement of molecules in opposite directions. Both modes are active in dielectric measurements due to small residual polarization being a consequence of the helical superstructure.

  12. Chemical potential of liquids and mixtures via adaptive resolution simulation

    SciTech Connect

    Agarwal, Animesh; Wang, Han Site, Luigi Delle; Schütte, Christof

    2014-07-21

    We employ the adaptive resolution approach AdResS, in its recently developed Grand Canonical-like version (GC-AdResS) [H. Wang, C. Hartmann, C. Schütte, and L. Delle Site, Phys. Rev. X 3, 011018 (2013)], to calculate the excess chemical potential, μ{sup ex}, of various liquids and mixtures. We compare our results with those obtained from full atomistic simulations using the technique of thermodynamic integration and show a satisfactory agreement. In GC-AdResS, the procedure to calculate μ{sup ex} corresponds to the process of standard initial equilibration of the system; this implies that, independently of the specific aim of the study, μ{sup ex}, for each molecular species, is automatically calculated every time a GC-AdResS simulation is performed.

  13. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

    SciTech Connect

    Martínez-Ruiz, F. J.; Blas, F. J.; Moreno-Ventas Bravo, A. I.

    2015-09-14

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related

  14. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

    NASA Astrophysics Data System (ADS)

    Martínez-Ruiz, F. J.; Moreno-Ventas Bravo, A. I.; Blas, F. J.

    2015-09-01

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ11 = σ22, with the same dispersive energy between like species, ɛ11 = ɛ22, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janec̆ek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances rc and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance rc is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the molecules

  15. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture.

    PubMed

    Martínez-Ruiz, F J; Moreno-Ventas Bravo, A I; Blas, F J

    2015-09-14

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ11 = σ22, with the same dispersive energy between like species, ϵ11 = ϵ22, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janec̆ek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances rc and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance rc is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the molecules

  16. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture.

    PubMed

    Martínez-Ruiz, F J; Moreno-Ventas Bravo, A I; Blas, F J

    2015-09-14

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ11 = σ22, with the same dispersive energy between like species, ϵ11 = ϵ22, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janec̆ek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances rc and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance rc is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the molecules

  17. Liquid crystal nanocomposites produced by mixtures of hydrogen bonded achiral liquid crystals and functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Katranchev, B.; Petrov, M.; Keskinova, E.; Naradikian, H.; Rafailov, P. M.; Dettlaff-Weglikowska, U.; Spassov, T.

    2014-12-01

    The liquid crystalline (LC) nature of alkyloxybenzoic acids is preserved after adding of any mesogenic or non-mesogenic compound through hydrogen bonding. However, this noncovalent interaction provokes a sizable effect on the physical properties as, e. g. melting point and mesomorphic states. In the present work we investigate nanocomposites, prepared by mixture of the eighth homologue of p-n-alkyloxybenzoic acids (8OBA) with single-walled carbon nanotubes (SWCNT) with the purpose to modify the optical properties of the liquid crystal. We exercise optical control on the LC system by inserting SWCNT specially functionalized by carboxylic groups. Since the liquid crystalline state combines order and mobility at the molecular (nanoscale) level, molecular modification can lead to different macroscopical nanocomposite symmetry. The thermal properties of the functionalized nanocomposite are confirmed by DSC analyses. The mechanism of the interaction between surface-treated nanoparticles (functionalized nanotubes) and the liquid crystal 8OBA bent- dimer molecules is briefly discussed.

  18. A new developed velocity of sound measurement device for characterization of multi-component gas mixtures under elevated temperatures and pressures.

    PubMed

    Seibel, C; Suedmeyer, J; Fieback, T M

    2014-07-01

    Inline process control by measurement of velocity of sound of fluids is a direct and comprehensive technique [J. D. N. Cheeke and Z. Wang, "Acoustic wave gas sensors," Sens. Actuators B 59, 146-153 (1999); J. W. Grate, S. J. Martin, and R. M. White, "Acoustic wave microsensors," Anal. Chem. 65, 1868 (1993)]. Depending on the varying conditions of measuring fluid(s), temperatures and pressures, it is a challenging task to find the best possible acoustic setup. Taking this background into account, a velocity of sound measurement device for temperatures up to 475 K and pressures up to 24 MPa was designed and assembled that is to be used for testing different resonator types. Two bulk acoustic wave resonators out of the commonly used lead zirconatetitanate compound (PZT) were tested at different test fluids under temperatures up to 423.15 K and pressures up to 24 MPa [S. Gebhardt, L. Seffner, F. Schlenkirch, and A. Schönecker, "PZT thick films for sensor and actuator applications," J. Eur. Ceram. Soc. 27, 4177-4180 (2007)]. Initially the pure gases methane, ethane, carbon dioxide, nitrogen, and helium were measured, followed by multi-component gas mixtures. Beside methane-based binary and ternary gas mixtures, a quaternary gas mixture comprising methane, ethane, carbon dioxide, and helium was analyzed. Results for all measurement fluids in a broad temperature and pressure range show a relative deviation to theoretical values derived from GERG-2008 smaller than 0.5%.

  19. Dielectrophoretic manipulation of the mixture of isotropic and nematic liquid

    PubMed Central

    Kim, Soo-Dong; Lee, Bomi; Kang, Shin-Woong; Song, Jang-Kun

    2015-01-01

    In various applications involving liquid crystals, the manipulation of the nanoscale molecular assembly and microscale director alignment is highly useful. Here we show that a nematic–isotropic mixture, a unique bi-liquid system, has potential for the fabrication of microstructures having an ordered phase within a disordered phase, or vice versa. The volume expansion and shrinkage, migration, splitting, mergence and elongation of one phase within the other are easily accomplished via thermal treatment and dielectrophoretic manipulation. This is particularly achievable when one phase is suspended in the middle. In that case, a highly biased ordered-phase preference of surfaces, that is, the nematic-philic nature of a polyimide layer and the nematic-phobic nature of a self-assembled monolayer of chlorosilane derivatives, is used. Further, by combining this approach with photopolymerization, the patterned microstructure is solidified as a patterned polymer film having both isotropic and anisotropic molecular arrangements simultaneously, or as a template with a morphological variation. PMID:26242251

  20. Biomass Pretreatment using Ionic Liquid and Glycerol Mixtures

    NASA Astrophysics Data System (ADS)

    Lynam, Joan Goerss

    Lignocellulosic biomass is a renewable, sustainable resource that can replace or supplement fossil fuels use for liquid fuels and chemicals. However, its recalcitrant structure including interwoven cellulose, hemicelluloses, and lignin biomacromolecules is challenging to deconstruct. Pretreating biomass so that it can be converted to useful liquids dominates process economics. Many pretreatment methods exist, but most require hazardous chemicals or processing conditions. Many ionic liquids (ILs), salts molten below 100°C, can be used to deconstruct lignocellulosic biomass and are less hazardous than the volatile organic compounds typically used. While effective, relatively safe, and recyclable, ILs are expensive. To reduce costs, dilution with other safe compounds is desirable, if there is no impact on deconstruction efficiency. Glycerol, a food additive, is inexpensive and becoming even more so since it is a by-product of the burgeoning biodiesel industry. Use of glycerol as an additive or diluent for ILs is extensively evaluated in this work. Rice hulls are an abundant biomass, with over 100 million tons produced per year, but with little practical use. The IL 1-ethyl-3-methylimidazolium formate ([C2mim][O2CH] or EMIM Form) when mixed with an equal amount of glycerol has been shown to be effective in pretreating rice hulls. Ambient pressure, a pretreatment temperature of 110°C, and a reaction time of three hours produced rice hulls that could be enzymatically hydrolyzed to give reasonably good glucose and xylose yields considering the recalcitrance of this silica-armored biomass. The IL [C2mim][O2CH] was also effective when mixed with an equal amount of glycerol to pretreat loblolly pine, a fast-growing softwood. Loblolly pine was pretreated at 140°C for three hours to produce a solid rich in cellulose and hemicelluloses, while a lignin-rich product could be precipitated from the IL. Similar products were obtained from pretreatment with a mixture of 75% 1

  1. Crystallization of classical multicomponent plasmas

    SciTech Connect

    Medin, Zach; Cumming, Andrew

    2010-03-15

    We develop a method for calculating the equilibrium properties of the liquid-solid phase transition in a classical, ideal, multicomponent plasma. Our method is a semianalytic calculation that relies on extending the accurate fitting formulas available for the one-, two-, and three-component plasmas to the case of a plasma with an arbitrary number of components. We compare our results to those of C. J. Horowitz et al. [Phys. Rev. E 75, 066101 (2007)], who used a molecular-dynamics simulation to study the chemical properties of a 17-species mixture relevant to the ocean-crust boundary of an accreting neutron star at the point where half the mixture has solidified. Given the same initial composition as Horowitz et al., we are able to reproduce to good accuracy both the liquid and solid compositions at the half-freezing point; we find abundances for most species within 10% of the simulation values. Our method allows the phase diagram of complex mixtures to be explored more thoroughly than possible with numerical simulations. We briefly discuss the implications for the nature of the liquid-solid boundary in accreting neutron stars.

  2. Thermoelectric-enhanced, liquid-based cooling of a multi-component electronic system

    SciTech Connect

    Chainer, Timothy J; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Steinke, Mark E

    2015-05-12

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled structure, a thermal conduction path coupling the electronic component and the liquid-cooled structure, a coolant loop in fluid communication with a coolant-carrying channel of the liquid-cooled structure, and an outdoor-air-cooled heat exchange unit coupled to facilitate heat transfer from the liquid-cooled structure via, at least in part, the coolant loop. The thermoelectric array facilitates transfer of heat from the electronic component to the liquid-cooled structure, and the heat exchange unit cools coolant passing through the coolant loop by dissipating heat from the coolant to outdoor ambient air. In one implementation, temperature of coolant entering the liquid-cooled structure is greater than temperature of the outdoor ambient air to which heat is dissipated.

  3. Thermoelectric-enhanced, liquid-based cooling of a multi-component electronic system

    SciTech Connect

    Chainer, Timothy J; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Steinke, Mark E

    2015-11-10

    Methods are provided for facilitating cooling of an electronic component. The methods include providing: a liquid-cooled structure, a thermal conduction path coupling the electronic component and the liquid-cooled structure, a coolant loop in fluid communication with a coolant-carrying channel of the liquid-cooled structure, and an outdoor-air-cooled heat exchange unit coupled to facilitate heat transfer from the liquid-cooled structure via, at least in part, the coolant loop. The thermoelectric array facilitates transfer of heat from the electronic component to the liquid-cooled structure, and the heat exchange unit cools coolant passing through the coolant loop by dissipating heat from the coolant to outdoor ambient air. In one implementation, temperature of coolant entering the liquid-cooled structure is greater than temperature of the outdoor ambient air to which heat is dissipated.

  4. Correlations and scaling properties of nonequilibrium fluctuations in liquid mixtures

    NASA Astrophysics Data System (ADS)

    Brogioli, Doriano; Croccolo, Fabrizio; Vailati, Alberto

    2016-08-01

    Diffusion in liquids is accompanied by nonequilibrium concentration fluctuations spanning all the length scales comprised between the microscopic scale a and the macroscopic size of the system, L . Up to now, theoretical and experimental investigations of nonequilibrium fluctuations have focused mostly on determining their mean-square amplitude as a function of the wave vector. In this work, we investigate the local properties of nonequilibrium fluctuations arising during a stationary diffusion process occurring in a binary liquid mixture in the presence of a uniform concentration gradient, ∇ c0 . We characterize the fluctuations by evaluating statistical features of the system, including the mean-square amplitude of fluctuations and the corrugation of the isoconcentration surfaces; we show that they depend on a single mesoscopic length scale l =√{a L } representing the geometric average between the microscopic and macroscopic length scales. We find that the amplitude of the fluctuations is very small in practical cases and vanishes when the macroscopic length scale increases. The isoconcentration surfaces, or fronts of diffusion, have a self-affine structure with corrugation exponent H =1 /2 . Ideally, the local fractal dimension of the fronts of diffusion would be Dl=d -H , where d is the dimensionality of the space, while the global fractal dimension would be Dg=d -1 . The transition between the local and global regimes occurs at a crossover length scale of the order of the microscopic length scale a . Therefore, notwithstanding the fact that the fronts of diffusion are corrugated, they appear flat at all the length scales probed by experiments, and they do not exhibit a fractal structure.

  5. Correlations and scaling properties of nonequilibrium fluctuations in liquid mixtures.

    PubMed

    Brogioli, Doriano; Croccolo, Fabrizio; Vailati, Alberto

    2016-08-01

    Diffusion in liquids is accompanied by nonequilibrium concentration fluctuations spanning all the length scales comprised between the microscopic scale a and the macroscopic size of the system, L. Up to now, theoretical and experimental investigations of nonequilibrium fluctuations have focused mostly on determining their mean-square amplitude as a function of the wave vector. In this work, we investigate the local properties of nonequilibrium fluctuations arising during a stationary diffusion process occurring in a binary liquid mixture in the presence of a uniform concentration gradient, ∇c_{0}. We characterize the fluctuations by evaluating statistical features of the system, including the mean-square amplitude of fluctuations and the corrugation of the isoconcentration surfaces; we show that they depend on a single mesoscopic length scale l=sqrt[aL] representing the geometric average between the microscopic and macroscopic length scales. We find that the amplitude of the fluctuations is very small in practical cases and vanishes when the macroscopic length scale increases. The isoconcentration surfaces, or fronts of diffusion, have a self-affine structure with corrugation exponent H=1/2. Ideally, the local fractal dimension of the fronts of diffusion would be D_{l}=d-H, where d is the dimensionality of the space, while the global fractal dimension would be D_{g}=d-1. The transition between the local and global regimes occurs at a crossover length scale of the order of the microscopic length scale a. Therefore, notwithstanding the fact that the fronts of diffusion are corrugated, they appear flat at all the length scales probed by experiments, and they do not exhibit a fractal structure. PMID:27627281

  6. Membrane permeation process for dehydration of organic liquid mixtures using sulfonated ion-exchange polyalkene membranes

    DOEpatents

    Cabasso, Israel; Korngold, Emmanuel

    1988-01-01

    A membrane permeation process for dehydrating a mixture of organic liquids, such as alcohols or close boiling, heat sensitive mixtures. The process comprises causing a component of the mixture to selectively sorb into one side of sulfonated ion-exchange polyalkene (e.g., polyethylene) membranes and selectively diffuse or flow therethrough, and then desorbing the component into a gas or liquid phase on the other side of the membranes.

  7. Metastable sound speed in gas-liquid mixtures

    NASA Technical Reports Server (NTRS)

    Bursik, J. W.; Hall, R. M.

    1979-01-01

    A new method of calculating speed of sound for two-phase flow is presented. The new equation assumes no phase change during the propagation of an acoustic disturbance and assumes that only the total entropy of the mixture remains constant during the process. The new equation predicts single-phase values for the speed of sound in the limit of all gas or all liquid and agrees with available two-phase, air-water sound speed data. Other expressions used in the two-phase flow literature for calculating two-phase, metastable sound speed are reviewed and discussed. Comparisons are made between the new expression and several of the previous expressions -- most notably a triply isentropic equation as used, a triply isentropic equation as used, among others, by Karplus and by Wallis. Appropriate differences are pointed out and a thermodynamic criterion is derived which must be satisfied in order for the triply isentropic expression to be thermodynamically consistent. This criterion is not satisfied for the cases examined, which included two-phase nitrogen, air-water, two-phase parahydrogen, and steam-water. Consequently, the new equation derived is found to be superior to the other equations reviewed.

  8. New phase equilibrium analyzer for determination of the vapor-liquid equilibrium of carbon dioxide and permanent gas mixtures for carbon capture and storage.

    PubMed

    Ke, Jie; Parrott, Andrew J; Sanchez-Vicente, Yolanda; Fields, Peter; Wilson, Richard; Drage, Trevor C; Poliakoff, Martyn; George, Michael W

    2014-08-01

    A high-pressure, phase equilibrium analyzer incorporating a fiber-optic reflectometer is described. The analyzer has been designed for measuring the vapor-liquid equilibrium data of multi-component mixtures of carbon dioxide and permanent gases, providing a novel tool to acquire of a large number of phase equilibrium data for the development of the new carbon capture and storage technologies. We demonstrate that the analyzer is suitable for determining both the bubble- and dew-point lines at temperature from 253 K and pressure up to 25 MPa using pure CO2 and two binary mixtures of CO2 + N2 and CO2 + H2. PMID:25173315

  9. Simultaneous multicomponent spectrophotometric monitoring of methyl and propyl parabens using multivariate statistical methods after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction

    NASA Astrophysics Data System (ADS)

    Khani, Rouhollah; Ghasemi, Jahan B.; Shemirani, Farzaneh

    2014-03-01

    A powerful and efficient signal-preprocessing technique that combines local and multiscale properties of the wavelet prism with the global filtering capability of orthogonal signal correction (OSC) is applied for pretreatment of spectroscopic data of parabens as model compounds after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction method (IL-DLLME). In the proposed technique, a mixture of a water-immiscible ionic liquid (as extraction solvent) [Hmim][PF6] and disperser solvent is injected into an aqueous sample solution containing one of the IL's ions, NaPF6, as extraction solvent and common ion source. After preconcentration, the absorbance of the extracted compounds was measured in the wavelength range of 200-700 nm. The wavelet orthogonal signal correction with partial least squares (WOSC-PLS) method was then applied for simultaneous determination of each individual compound. Effective parameters, such as amount of IL, volume of the disperser solvent and amount of NaPF6, were inspected by central composite design to identify the most important parameters and their interactions. The effect of pH on the sensitivity and selectivity was studied according to the net analyte signal (NAS) for each component. Under optimum conditions, enrichment factors of the studied compounds were 75 for methyl paraben (MP) and 71 for propyl paraben (PP). Limits of detection for MP and PP were 4.2 and 4.8 ng mL-1, respectively. The root mean square errors of prediction for MP and PP were 0.1046 and 0.1275 μg mL-1, respectively. The practical applicability of the developed method was examined using hygienic, cosmetic, pharmaceutical and natural water samples.

  10. Simultaneous multicomponent spectrophotometric monitoring of methyl and propyl parabens using multivariate statistical methods after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction.

    PubMed

    Khani, Rouhollah; Ghasemi, Jahan B; Shemirani, Farzaneh

    2014-03-25

    A powerful and efficient signal-preprocessing technique that combines local and multiscale properties of the wavelet prism with the global filtering capability of orthogonal signal correction (OSC) is applied for pretreatment of spectroscopic data of parabens as model compounds after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction method (IL-DLLME). In the proposed technique, a mixture of a water-immiscible ionic liquid (as extraction solvent) [Hmim][PF6] and disperser solvent is injected into an aqueous sample solution containing one of the IL's ions, NaPF6, as extraction solvent and common ion source. After preconcentration, the absorbance of the extracted compounds was measured in the wavelength range of 200-700 nm. The wavelet orthogonal signal correction with partial least squares (WOSC-PLS) method was then applied for simultaneous determination of each individual compound. Effective parameters, such as amount of IL, volume of the disperser solvent and amount of NaPF6, were inspected by central composite design to identify the most important parameters and their interactions. The effect of pH on the sensitivity and selectivity was studied according to the net analyte signal (NAS) for each component. Under optimum conditions, enrichment factors of the studied compounds were 75 for methyl paraben (MP) and 71 for propyl paraben (PP). Limits of detection for MP and PP were 4.2 and 4.8 ng mL(-)(1), respectively. The root mean square errors of prediction for MP and PP were 0.1046 and 0.1275 μg mL(-)(1), respectively. The practical applicability of the developed method was examined using hygienic, cosmetic, pharmaceutical and natural water samples.

  11. A direct method for calculating thermodynamic factors for liquid mixtures using the Permuted Widom test particle insertion method

    NASA Astrophysics Data System (ADS)

    Prasaad Balaji, Sayee; Schnell, Sondre K.; McGarrity, Erin S.; Vlugt, Thijs J. H.

    2013-01-01

    Understanding mass transport in liquids by mutual diffusion is an important topic for many applications in chemical engineering. The reason for this is that diffusion is often the rate limiting step in chemical reactors and separators. In multicomponent liquid mixtures, transport diffusion can be described by both generalized Fick's law and the Maxwell-Stefan theory. The Maxwell-Stefan and Fick approaches in an n-component system are related by the so-called thermodynamic factor [R. Taylor and H.A. Kooijman, Chem. Eng. Commun, 102, 87 (1991)]. As Fick diffusivities can be measured in experiments and Maxwell-Stefan diffusivities can be obtained from molecular simulations/theory, the thermodynamic factors bridge the gap between experiments and molecular simulations/theory. It is therefore desirable to be able to compute thermodynamic factors from molecular simulations. Unfortunately, presently used simulation techniques for computing thermodynamic factors are inefficient and often require numerical differentiation of simulation results. In this work, we propose a modified version of the Widom test-particle method to compute thermodynamic factors from a single simulation. This method is found to be more efficient than the conventional Widom test particle insertion method combined with numerical differentiation of simulation results. The approach is tested for binary systems consisting of Lennard-Jones particles. The thermodynamic factors computed from the simulation and from numerically differentiating the activity coefficients obtained from the conventional Widom test particle insertion method are in excellent agreement.

  12. Determination of solubility parameters of ionic liquids and ionic liquid/solvent mixtures from intrinsic viscosity.

    PubMed

    Weerachanchai, Piyarat; Wong, Yuewen; Lim, Kok Hwa; Tan, Timothy Thatt Yang; Lee, Jong-Min

    2014-11-10

    The total and partial solubility parameters (dispersion, polar and hydrogen-bonding solubility parameters) of ten ionic liquids were determined. Intrinsic viscosity approaches were used that encompassed a one-dimensional method (1D-Method), and two different three-dimensional methods (3D-Method1 and 3D-Method2). The effect of solvent type, the dimethylacetamide (DMA) fraction in the ionic liquid, and dissolution temperature on solubility parameters were also investigated. For all types of effect, both the 1D-Method and 3D-Method2 present the same trend in the total solubility parameter. The partial solubility parameters are influenced by the cation and anion of the ionic liquid. Considering the effect on partial solubility parameters of the solvent type in the ionic liquid, it was observed that in both 3D methods, the dispersion and polar parameters of a 1-ethyl-3-methylimidazolium acetate/solvent (60:40 vol %) mixture tend to increase as the total solubility parameter of the solvent increases. PMID:25145759

  13. Highly viscous liquid crystalline mixtures: the alternative to liquid crystalline elastomers

    NASA Astrophysics Data System (ADS)

    Shibaev, Petr; Schlesier, Cristina; Newman, Leah; McDonald, Scott

    2012-02-01

    Novel highly viscous liquid crystalline materials based on mixtures of glass forming oligomers and low molar mass liquid crystals were recently designed [1, 2] and studied. In this communication the novel data are presented, the analysis and discussion are extended. It is shown that viscoelastic properties of the materials are due to the physical entanglements between cyclic oligomers and low molar mass mesogens, not due to the chemical crosslinks between molecular moities. However, the mechanical properties of these viscoelastic materials resemble those of chemically crosslinked elastomers (elasticity and reversibility of deformations). The properties of chiral and non-chiral materials loaded with ferromagnetic nanoparticles are discussed in detail. Cholesteric materials undergo gigantic color changes in the wide spectral range under the deformation that allows distant detection of deformation and determination the anisotropy of deformation and its type. The materials doped with laser dyes become mechanically tunable lasers themselves and emit coherent light while pumped by external laser. A simple model is suggested to account for the observed effects; physical properties of the novel materials and liquid crystalline elastomers are compared and discussed. [4pt] [1] P.V. Shibaev, C. Schlesier, R. Uhrlass, S. Woodward, E. Hanelt, Liquid Crystals, 37:12, 1601-1604 [0pt] [2] P.V. Shibaev, P. Riverra, D. Teter, S. Marsico, M. Sanzari, V. Ramakrishnan, E. Hanelt, Optics Express, 16, 2965 (2008)

  14. Preliminary Investigation of Performance and Starting Characteristics of Liquid Fluorine : Liquid Oxygen Mixtures with Jet Fuel

    NASA Technical Reports Server (NTRS)

    Rothenberg, Edward A; Ordin, Paul M

    1954-01-01

    The performance of jet fuel with an oxidant mixture containing 70 percent liquid fluorine and 30 percent liquid oxygen by weight was investigated in a 500-pound-thrust engine operating at a chamber pressure of 300 pounds per square inch absolute. A one-oxidant-on-one-fuel skewed-hole impinging-jet injector was evaluated in a chamber of characteristic length equal to 50 inches. A maximum experimental specific impulse of 268 pound-seconds per pound was obtained at 25 percent fuel, which corresponds to 96 percent of the maximum theoretical specific impulse based on frozen composition expansion. The maximum characteristic velocity obtained was 6050 feet per second at 23 percent fuel, or 94 percent of the theoretical maximum. The average thrust coefficient was 1.38 for the 500-pound thrust combustion-chamber nozzle used, which was 99 percent of the theoretical (frozen) maximum. Mixtures of fluorine and oxygen were found to be self-igniting with jet fuel with fluorine concentrations as low as 4 percent, when low starting propellant flow rated were used.

  15. Multicomponent diffusion revisited

    NASA Astrophysics Data System (ADS)

    Lam, S. H.

    2006-07-01

    The derivation of the multicomponent diffusion law is revisited. Following Furry [Am. J. Phys. 16, 63 (1948)], Williams [Am. J. Phys. 26, 467 (1958); Combustion Theory, 2nd ed. (Benjamin/Cummings , Menlo Park, CA,1985)] heuristically rederived the classical kinetic theory results using macroscopic equations, and pointed out that the dynamics of the mixture fluid had been assumed inviscid. This paper generalizes the derivation, shows that the inviscid assumption can easily be relaxed to add a new term to the classical diffusion law, and the thermal diffusion term can also be easily recovered. The nonuniqueness of the multicomponent diffusion coefficient matrix is emphasized and discussed.

  16. Thermal properties of liquid crystal hexylbenzoic acid/octyloxybenzoic acid mixture

    NASA Astrophysics Data System (ADS)

    Okumus, M.

    2015-03-01

    The thermal behaviors of binary mixture formed from hydrogen bonded nematic liquid crystals 4-hexylbenzoic acid and 4-(octyloxy)benzoic acid, were investigated by differential scanning calorimetry (DSC). The phase transition temperatures and enthalpies were determined by using calorimetric methods on DSC. The DSC results clearly indicate that the produced liquid crystal mixture displays liquid crystalline properties. The phase transition temperature values increase with increasing heating rate between 5 °C/min and 20 °C/min, and the calculated activation energy values show that the reaction arising during the phase transitions of the mixture is regular.

  17. On the Crystallization of Compacted and Chunky Graphite from Liquid Multicomponent Iron-Carbon-Silicon-Based Melts

    NASA Astrophysics Data System (ADS)

    Stefanescu, D. M.; Huff, R.; Alonso, G.; Larrañaga, P.; De la Fuente, E.; Suarez, R.

    2016-08-01

    Extensive SEM work was carried out on deep-etched specimens to reveal the evolution of compacted and chunky graphite in magnesium-modified multicomponent Fe-C-Si alloys during early solidification and at room temperature. The findings of this research were then integrated in the current body of knowledge to produce an understanding of the crystallization of compacted and chunky graphite. It was confirmed that growth from the liquid for both compacted and chunky graphite occurs radially from a nucleus, as foliated crystals and dendrites. The basic building blocks of the graphite aggregates are hexagonal faceted graphite platelets with nanometer height and micrometer width. Thickening of the platelets occurs through growth of additional graphene layers nucleated at the ledges of the graphite prism. Additional thickening resulting in complete joining of the platelets may occur from the recrystallization of the amorphous carbon that has diffused from the liquid through the austenite, once the graphite aggregate is enveloped in austenite. With increasing magnesium levels, the foliated graphite platelets progressively aggregate along the c-axis forming clusters. The clusters that have random orientation, eventually produce blocky graphite, as the spaces between the parallel platelets disappear. This is typical for compacted graphite irons and tadpole graphite. The chunky graphite aggregates investigated are conical sectors of graphite platelets stacked along the c-axis. The foliated dendrites that originally develop radially from a common nucleus may aggregate along the c-axis forming blocky graphite that sometimes exhibits helical growth. The large number of defects (cavities) observed in all graphite aggregates supports the mechanism of graphite growth as foliated crystals and dendrites.

  18. Understanding positive and negative deviations in polarity of ionic liquid mixtures by pseudo-solvent approach.

    PubMed

    Beniwal, Vijay; Kumar, Anil

    2016-08-24

    Physico-chemical properties of liquid mixtures in general display large deviations from linear behaviour, arising out of complex specific and non-specific intermolecular interactions. The polarity of liquid mixtures displaying large positive and negative deviations can be minimized and linear mixing can be achieved in liquids using a pseudo-solvent methodology. The work described herein is designed to investigate the influence of different physical parameters on the linear pseudo-solvent composition in ionic liquid mixtures. For this purpose, we have determined the deviations from linearity, ΔE values (defined as given by ) for binary mixtures of a variety of ionic liquids, including two molecular solvents, DMSO and formamide. Firstly, the investigations were carried out in three 1-butyl-3-methylimidazolium cation based aprotic ionic liquids and the roles of anionic structure and hydrogen bond acceptor basicities (β values) of the ionic liquids were determined. The influence of the cationic structure, i.e., the hydrogen bond donor acidity (α values) and non-associative nature of the ionic liquids, was determined using C2-methylated analogs, 1-butyl-2,3-dimethylimidazolium cation based ionic liquids. The role of the protic nature of ionic liquids was studied in two protic ionic liquids, viz., 1-methylimidazolium formate and 1-methylimidazolium acetate. The effects of the temperature, pseudo-solvent structure and solvatochromic probe structure on the ΔE values were also explored.

  19. Understanding positive and negative deviations in polarity of ionic liquid mixtures by pseudo-solvent approach.

    PubMed

    Beniwal, Vijay; Kumar, Anil

    2016-08-24

    Physico-chemical properties of liquid mixtures in general display large deviations from linear behaviour, arising out of complex specific and non-specific intermolecular interactions. The polarity of liquid mixtures displaying large positive and negative deviations can be minimized and linear mixing can be achieved in liquids using a pseudo-solvent methodology. The work described herein is designed to investigate the influence of different physical parameters on the linear pseudo-solvent composition in ionic liquid mixtures. For this purpose, we have determined the deviations from linearity, ΔE values (defined as given by ) for binary mixtures of a variety of ionic liquids, including two molecular solvents, DMSO and formamide. Firstly, the investigations were carried out in three 1-butyl-3-methylimidazolium cation based aprotic ionic liquids and the roles of anionic structure and hydrogen bond acceptor basicities (β values) of the ionic liquids were determined. The influence of the cationic structure, i.e., the hydrogen bond donor acidity (α values) and non-associative nature of the ionic liquids, was determined using C2-methylated analogs, 1-butyl-2,3-dimethylimidazolium cation based ionic liquids. The role of the protic nature of ionic liquids was studied in two protic ionic liquids, viz., 1-methylimidazolium formate and 1-methylimidazolium acetate. The effects of the temperature, pseudo-solvent structure and solvatochromic probe structure on the ΔE values were also explored. PMID:27523572

  20. Investigation of simultaneous biosorption of copper(II) and chromium(VI) on dried Chlorella vulgaris from binary metal mixtures: Application of multicomponent adsorption isotherms

    SciTech Connect

    Aksu, Z.; Acikel, U.; Kutsal, T.

    1999-02-01

    Although the biosorption of single metal ions to various kinds of microorganisms has been extensively studied and the adsorption isotherms have been developed for only the single metal ion situation, very little attention has been given to the bioremoval and expression of adsorption isotherms of multimetal ions systems. In this study the simultaneous biosorption of copper(II) and chromium(VI) to Chlorella vulgaris from a binary metal mixture was studied and compared with the single metal ion situation in a batch stirred system. The effects of pH and single- and dual-metal ion concentrations on the equilibrium uptakes were investigated. In previous studies the optimum biosorption pH had been determined as 4.0 for copper(II) and as 2.0 for chromium(VI). Multimetal ion biosorption studies were performed at these two pH values. It was observed that the equilibrium uptakes of copper(II) or chromium(VI) ions were changed due to the biosorption pH and the presence of other metal ions. Adsorption isotherms were developed for both single- and dual-metal ions systems at these two pH values, and expressed by the mono- and multicomponent Langmuir and Freundlich adsorption models. Model parameters were estimated by nonlinear regression. It was seen that the adsorption equilibrium data fitted very well to the competitive Freundlich model in the concentration ranges studied.

  1. Some aspects in the design of multicomponent reactive distillation columns with a reacting core: Mixtures containing inerts

    SciTech Connect

    Espinosa, J.; Aguirre, P.; Perez, G.

    1996-12-01

    Some aspects related to the design of reactive distillation columns with a reacting core are addressed in this paper. A set of transformed composition variables proposed in a previous paper is used to develop both the design equations and the reactive residue curve maps for quaternary reacting mixtures. Also, conventional residue curve maps are employed to achieve a better physical and conceptual insight into the relationships between the different constitutive parts of a column with a reacting core. Limitations in product specifications of entirely reactive distillation columns are explained by means of reactive residue curve maps, and a new feasibility criterion of a given separation for reactive columns with a reacting core is also developed on the basis of the two extreme operation conditions of a column. Finally, the behavior of column profiles for both high-conversion and low-conversion cases is analyzed and optimal product specifications are suggested to obtain high purity products. As the authors concluded in previous works, the inerts have a central role in both the design and synthesis of a reactive distillation column. All the concepts are applied to azeotrope-forming mixtures.

  2. Ionic liquids and deep eutectic mixtures: sustainable solvents for extraction processes.

    PubMed

    Pena-Pereira, Francisco; Namieśnik, Jacek

    2014-07-01

    In recent years, ionic liquids and deep eutectic mixtures have demonstrated great potential in extraction processes relevant to several scientific and technological activities. This review focuses on the applicability of these sustainable solvents in a variety of extraction techniques, including but not limited to liquid- and solid-phase (micro) extraction, microwave-assisted extraction, ultrasound-assisted extraction and pressurized liquid extraction. Selected applications of ionic liquids and deep eutectic mixtures on analytical method development, removal of environmental pollutants, selective isolation, and recovery of target compounds, purification of fuels, and azeotrope breaking are described and discussed.

  3. Dynamic amplification of light signals in photorefractive ferroelectric liquid crystalline mixtures.

    PubMed

    Sasaki, Takeo; Kajikawa, Satoshi; Naka, Yumiko

    2014-01-01

    The photorefractive effect in photoconductive ferroelectric liquid crystals that contain photoconductive chiral compounds was investigated. Terthiophene compounds with chiral structures were chosen as the photoconductive chiral compounds, and they were mixed with an achiral smectic C liquid crystal. The mixtures exhibit the ferroelectric chiral smectic C phase. The photorefractivity of the mixtures was investigated by two-beam coupling experiments. It was found that the ferroelectric liquid crystals containing the photoconductive chiral compound exhibit a large gain coefficient of over 1200 cm(-1) and a fast response time of 1 ms. Real-time dynamic amplification of an optical image signal of over 30 fps using the photorefractive ferroelectric liquid crystal was demonstrated.

  4. Liquid-liquid equilibria of binary mixtures of a lipidic ionic liquid with hydrocarbons.

    PubMed

    Green, Blane D; Badini, Alexander J; O'Brien, Richard A; Davis, James H; West, Kevin N

    2016-01-28

    Although structurally diverse, many ionic liquids (ILs) are polar in nature due to the strong coulombic forces inherent in ionic compounds. However, the overall polarity of the IL can be tuned by incorporating significant nonpolar content into one or more of the constituent ions. In this work, the binary liquid-liquid equilibria of one such IL, 1-methyl-3-(Z-octadec-9-enyl)imidazolium bistriflimide, with several hydrocarbons (n-hexane, n-octane, n-decane, cyclohexane, methylcyclohexane, 1-octene) is measured over the temperature range 0-70 °C at ambient pressure using a combination of cloud point and gravimetric techniques. The phase behavior of the systems are similar in that they exhibit two phases: one that is 60-90 mole% hydrocarbon and a second phase that is nearly pure hydrocarbon. Each phase exhibits a weak dependence of composition on temperature (steep curve) above ∼10 °C, likely due to swelling and restructuring of the nonpolar nano-domains of the IL being limited by energetically unfavorable restructuring in the polar nano-domains. The solubility of the n-alkanes decreases with increasing size (molar volume), a trend that continues for the cyclic alkanes, for which upper critical solution temperatures are observed below 70 °C. 1-Octene is found to be more soluble than n-octane, attributable to a combination of its lower molar volume and slightly higher polarity. The COSMO-RS model is used to predict the T-x'-x'' diagrams and gives good qualitative agreement of the observed trends. This work presents the highest known solubility of n-alkanes in an IL to date and tuning the structure of the ionic liquid to maximize the size/shape trends observed may provide the basis for enhanced separations of nonpolar species.

  5. Mixtures of protic ionic liquids and propylene carbonate as advanced electrolytes for lithium-ion batteries.

    PubMed

    Vogl, T; Menne, S; Balducci, A

    2014-12-01

    In this study we investigated the chemical-physical properties of mixtures containing the protic ionic liquid (PIL) N-butyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYRH4TFSI), propylene carbonate (PC) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in view of their use as electrolytes for lithium-ion batteries (LIBs). We showed that these electrolytic solutions might display conductivity and viscosity comparable to those of conventional electrolytes. Depending on the amount of PIL present inside the mixtures, such mixtures might also display the ability to suppress the anodic dissolution of Al. Furthermore, we showed that the coordination of lithium ions by TFSI in PIL-PC mixtures appears to be different than the one observed for mixtures of PC and aprotic ionic liquids (AILs). When used in combination with a battery electrode, e.g. lithium iron phosphate (LFP), these mixtures allow the achievement of high performance also at a very high C-rate.

  6. Multicomponent determination of 4-hydroxycoumarin anticoagulant rodenticides in blood serum by liquid chromatography with fluorescence detection.

    PubMed

    Felice, L J; Chalermchaikit, T; Murphy, M J

    1991-01-01

    A sensitive liquid chromatographic method was developed for the analysis of 4-hydroxycoumarin anticoagulant rodenticides in blood serum. The method can simultaneously measure the serum levels of five anticoagulant rodenticides: brodifacoum, bromadiolone, coumatetralyl, difenacoum, and warfarin. Serum proteins are precipitated with acetonitrile and the supernatant is mixed with ethyl ether. The organic phase is separated, evaporated to dryness, and the residue subjected to chromatographic analysis. The anticoagulants are separated by reversed-phase gradient chromatography with fluorescence detection at an excitation wavelength of 318 nm and emission wavelength of 390 nm. Extraction efficiencies of 68.1 to 98.2% were obtained. The within-run precision (CV) ranged from 2.19 to 3.79% and the between-run precision (CV) from 3.72 to 9.57%. The anticoagulants can be quantitated at serum levels of 10 to 20 ng/mL. PMID:1943055

  7. Effect of water-table fluctuation on dissolution and biodegradation of a multi-component, light nonaqueous-phase liquid.

    PubMed

    Dobson, Richard; Schroth, Martin H; Zeyer, Josef

    2007-12-01

    Light nonaqueous-phase liquids (LNAPLs) such as gasoline and diesel fuel are among the most common causes of soil and groundwater contamination. Dissolution and subsequent advective transport of LNAPL components can negatively impact water supplies, while biodegradation is thought to be an important sink for this class of contaminants. We present a laboratory investigation of the effect of a water-table fluctuation on dissolution and biodegradation of a multi-component LNAPL (85% hexadecane, 5% toluene, 5% ethylbenzene, and 5% 2-methylnapthalene on a molar basis) in a pair of similar model aquifers (80 cm x 50 cm x 3 cm), one of which was subjected to a water-table fluctuation. Water-table fluctuation resulted in LNAPL and air entrapment below the water table, an increase in the vertical extent of the LNAPL source zone (by factor 6.7), and an increase in the volume of water passing through the source zone (by factor ~18). Effluent concentrations of dissolved LNAPL components were substantially higher and those of dissolved nitrate lower in the model aquifer where a fluctuation had been induced. Thus, water-table fluctuation led to enhanced biodegradation activity (28.3 mmol of nitrate consumed compared to 16.3 mmol in the model without fluctuation) as well as enhanced dissolution of LNAPL components. Despite the increased biodegradation, fluctuation led to increased elution of dissolved LNAPL components from the system (by factors 10-20). Hence, water-table fluctuations in LNAPL-contaminated aquifers might be expected to result in increased exposure of downgradient receptors to LNAPL components. Accordingly, water-table fluctuations in contaminated aquifers are probably undesirable unless the LNAPL is of minimal solubility or the dissolved-phase plume is not expected to reach a receptor due to distance or the presence of some form of containment.

  8. Playing with ionic liquid mixtures to design engineered CO2 separation membranes.

    PubMed

    Tomé, Liliana C; Florindo, Catarina; Freire, Carmen S R; Rebelo, Luís Paulo N; Marrucho, Isabel M

    2014-08-28

    Ionic liquids have been explored as attractive alternative media for CO2 separation not only due to their low volatility but also due to their highly tuneable nature. Aiming at designing highly efficient liquid phases for flue gas separation and natural gas purification, this work focuses on the use of binary ionic liquid mixtures containing sulfate and/or cyano-functionalized anions. Several mixtures were prepared and their gas transport properties through supported ionic liquid membranes (SILMs) were investigated. The thermophysical properties of these mixtures, namely viscosity and density (data presented and discussed in ESI), were also measured so that trends between transport properties and thermophysical properties could be evaluated. The results obtained indicate that depending on the anions mixed, membranes with fine-tuned gas permeabilities, diffusivities and solubilities can be obtained. Additionally, SILMs prepared with these ionic liquid mixtures are on the upper bound of the CO2/N2 separation, or even may surpass it, indicating their potential for separating CO2 in low-pressure post-combustion processes. Overall, the use of ionic liquid mixtures combining the most selective anions with the least viscous anions is a highly promising strategy to design advanced engineered liquid phases for CO2 separation membranes.

  9. "Zahraa", a Unani multicomponent herbal tea widely consumed in Syria: components of drug mixtures and alleged medicinal properties.

    PubMed

    Carmona, M D; Llorach, R; Obon, C; Rivera, D

    2005-12-01

    In Unani system of medicine, drugs consist of complex formulae with more than three components, for which, literature analysing these mixtures as they are sold in the market is scarce. In this paper, the main botanical components of the herbal tea known as "Zahraa" in Damascus, which contains between 6 and 14 species components is elucidated: Alcea damascena (Mout.) Mout. (Malvaceae), Aloysia triphylla (L'Herit.) Britt. (Malvaceae), Astragalus cf. amalecitanus Boiss., Cercis siliquastrum L. subsp. hebecarpa (Bornm.) Yalt. and subsp. siliquastrum. (Leguminosae), Colutea cilicica Boiss. et Bal. in Boiss. (Leguminosae), Crataegus aronia (L.) Bosc. ex DC. (Rosaceae), Cytisopsis pseudocytisus (Boiss.) Fertig. (Leguminosae), Eleagnus angustifolia L. (Eleagnaceae), Equisetum telmateia Ehrh. (Equisetaceae), Helichrysum stoechas (L.) Moench. subsp. barrelieri (Ten.) Nyman. (Compositae), Matricaria recutita L. (Compositae), Mentha longifolia L. subsp. noeana (Boiss. ex. Briq.) Briq. (Labiatae), Mentha spicata L. subsp. condensata (Briq.) Greuter and Burdet (Labiatae), Micromeria myrtifolia Boiss. and Hohen. in Boiss. (Labiatae), Paronychia argentea Lam. (Caryophyllaceae), Phlomis syriaca Boiss. (Labiatae), Rosa damascena Mill. (Rosaceae), Salvia fruticosa Mill. (Labiatae), Sambucus nigra L. (Caprifoliaceae), Spartium junceum L. (Leguminosae), Zea mays L. (Gramineae).

  10. "Zahraa", a Unani multicomponent herbal tea widely consumed in Syria: components of drug mixtures and alleged medicinal properties.

    PubMed

    Carmona, M D; Llorach, R; Obon, C; Rivera, D

    2005-12-01

    In Unani system of medicine, drugs consist of complex formulae with more than three components, for which, literature analysing these mixtures as they are sold in the market is scarce. In this paper, the main botanical components of the herbal tea known as "Zahraa" in Damascus, which contains between 6 and 14 species components is elucidated: Alcea damascena (Mout.) Mout. (Malvaceae), Aloysia triphylla (L'Herit.) Britt. (Malvaceae), Astragalus cf. amalecitanus Boiss., Cercis siliquastrum L. subsp. hebecarpa (Bornm.) Yalt. and subsp. siliquastrum. (Leguminosae), Colutea cilicica Boiss. et Bal. in Boiss. (Leguminosae), Crataegus aronia (L.) Bosc. ex DC. (Rosaceae), Cytisopsis pseudocytisus (Boiss.) Fertig. (Leguminosae), Eleagnus angustifolia L. (Eleagnaceae), Equisetum telmateia Ehrh. (Equisetaceae), Helichrysum stoechas (L.) Moench. subsp. barrelieri (Ten.) Nyman. (Compositae), Matricaria recutita L. (Compositae), Mentha longifolia L. subsp. noeana (Boiss. ex. Briq.) Briq. (Labiatae), Mentha spicata L. subsp. condensata (Briq.) Greuter and Burdet (Labiatae), Micromeria myrtifolia Boiss. and Hohen. in Boiss. (Labiatae), Paronychia argentea Lam. (Caryophyllaceae), Phlomis syriaca Boiss. (Labiatae), Rosa damascena Mill. (Rosaceae), Salvia fruticosa Mill. (Labiatae), Sambucus nigra L. (Caprifoliaceae), Spartium junceum L. (Leguminosae), Zea mays L. (Gramineae). PMID:16084679

  11. Formation of Multicomponent Star Structures at the Liquid/Solid Interface.

    PubMed

    Tahara, Kazukuni; Kaneko, Kyohei; Katayama, Keisuke; Itano, Shintaro; Nguyen, Chi Huan; Amorim, Deborah D D; De Feyter, Steven; Tobe, Yoshito

    2015-06-30

    To demonstrate key roles of multiple interactions between multiple components and multiple phases in the formation of an uncommon self-assembling pattern, we present here the construction of a porous hexagonal star (h-star) structure using a trigonal molecular building block at the liquid/solid interface. For this purpose, self-assembly of hexaalkoxy-substituted dehydrobenzo[12]annulene derivatives DBA-OCns was investigated at the tetradecane/graphite interface by means of scanning tunneling microscopy (STM). Monolayer structures were significantly influenced by coadsorbed tetradecane molecules depending on the alkyl chains length (C13-C16) of DBA-OCn. However, none of DBA-OCn molecules formed the expected trigonal complexes, indicating that an additional driving force is necessary for the formation of the trigonal complex and its assembly into the h-star structure. As a first approach, we employed the "guest induced structural change" for the formation of the h-star structure. In the presence of two guest molecules, nonsubstituted DBA and hexakis(phenylethynyl)benzene which fit the respective pores, an h-star structure was formed by DBA-OC15 at the tetradecane/graphite interface. Moreover, a tetradecane molecule was coadsorbed between a pair of alkyl chains of DBA-OC15, thereby blocking the interdigitation of the alkyl chain pairs. Therefore, the h-star structure results from the self-assembly of the four molecular components including the solvent molecule. The second approach is based on aggregation of perfluoroalkyl chains via fluorophilicity of DBA-F, in which the perfluoroalkyl groups are substituted at the end of three alkyl chains of DBA-OCn via p-phenylene linkers. A trigonal complex consisting of DBA-F and three tetradecane molecules formed an h-star structure, in which the perfluoroalkyl groups that orient into the alkane solution phase aggregated at the hexagonal pore via fluorophilicity. The present result provides useful insight into the design and

  12. Formation of Multicomponent Star Structures at the Liquid/Solid Interface.

    PubMed

    Tahara, Kazukuni; Kaneko, Kyohei; Katayama, Keisuke; Itano, Shintaro; Nguyen, Chi Huan; Amorim, Deborah D D; De Feyter, Steven; Tobe, Yoshito

    2015-06-30

    To demonstrate key roles of multiple interactions between multiple components and multiple phases in the formation of an uncommon self-assembling pattern, we present here the construction of a porous hexagonal star (h-star) structure using a trigonal molecular building block at the liquid/solid interface. For this purpose, self-assembly of hexaalkoxy-substituted dehydrobenzo[12]annulene derivatives DBA-OCns was investigated at the tetradecane/graphite interface by means of scanning tunneling microscopy (STM). Monolayer structures were significantly influenced by coadsorbed tetradecane molecules depending on the alkyl chains length (C13-C16) of DBA-OCn. However, none of DBA-OCn molecules formed the expected trigonal complexes, indicating that an additional driving force is necessary for the formation of the trigonal complex and its assembly into the h-star structure. As a first approach, we employed the "guest induced structural change" for the formation of the h-star structure. In the presence of two guest molecules, nonsubstituted DBA and hexakis(phenylethynyl)benzene which fit the respective pores, an h-star structure was formed by DBA-OC15 at the tetradecane/graphite interface. Moreover, a tetradecane molecule was coadsorbed between a pair of alkyl chains of DBA-OC15, thereby blocking the interdigitation of the alkyl chain pairs. Therefore, the h-star structure results from the self-assembly of the four molecular components including the solvent molecule. The second approach is based on aggregation of perfluoroalkyl chains via fluorophilicity of DBA-F, in which the perfluoroalkyl groups are substituted at the end of three alkyl chains of DBA-OCn via p-phenylene linkers. A trigonal complex consisting of DBA-F and three tetradecane molecules formed an h-star structure, in which the perfluoroalkyl groups that orient into the alkane solution phase aggregated at the hexagonal pore via fluorophilicity. The present result provides useful insight into the design and

  13. Thermodynamics of wax precipitation in petroleum mixtures

    SciTech Connect

    Lira-Galeana, C.; Firoozabadi, A.; Prausnitz, J.M. |

    1996-01-01

    A thermodynamic framework is developed for calculating wax precipitation in petroleum mixtures over a wide temperature range. The framework uses the experimentally supported assumption that precipitated wax consists of several solid phases; each solid phase is described as a pure component or pseudocomponent that does not mix with other solid phases. Liquid-phase properties are obtained from an equation of state. Calculated wax-precipitation data are in excellent agreement with experimental results for binary and multicomponent hydrocarbon mixtures, including petroleum.

  14. Thermodynamics of wax precipitation in petroleum mixtures

    SciTech Connect

    Firoozabadi, A.; Lira-Galeana, C.L.; Prausnitz, J.M.

    1995-12-01

    A thermodynamic framework is developed for calculating wax precipitation in petroleum mixtures over a wide temperature range. The framework assumes that the precipitated wax consists of several solid phases; each solid-phase is described as a pure component or pseudocomponent which does not mix with other solid phases. Liquid-phase properties are obtained from an equation of state. Calculated wax precipitation data are in excellent agreement with experimental results for binary and multicomponent hydrocarbon mixtures, including petroleum.

  15. Transient Numerical Modeling of the Combustion of Bi-Component Liquid Droplets: Methanol/Water Mixture

    NASA Technical Reports Server (NTRS)

    Marchese, A. J.; Dryer, F. L.

    1994-01-01

    This study shows that liquid mixtures of methanol and water are attractive candidates for microgravity droplet combustion experiments and associated numerical modeling. The gas phase chemistry for these droplet mixtures is conceptually simple, well understood and substantially validated. In addition, the thermodynamic and transport properties of the liquid mixture have also been well characterized. Furthermore, the results obtained in this study predict that the extinction of these droplets may be observable in ground-based drop to tower experiments. Such experiments will be conducted shortly followed by space-based experiments utilizing the NASA FSDC and DCE experiments.

  16. Exposure of Mammalian Cells to Air-Pollutant Mixtures at the Air-Liquid Interface

    EPA Science Inventory

    It has been widely accepted that exposure of mammalian cells to air-pollutant mixtures at the air-liquid interface is a more realistic approach than exposing cell under submerged conditions. The VITROCELL systems, are commercially available systems for air-liquid interface expo...

  17. Reversible and Non-Reactive Cellulose Separations from Ionic Liquid Mixtures with Compressed Carbon Dioxide

    PubMed Central

    Minnick, David L.; Scurto, Aaron M.

    2016-01-01

    A novel physical (non-reactive) separation of cellulose from an ionic liquid (IL) / cosolvent mixture by compressed carbon dioxide is presented. The precipitation is completely reversible and rapid within small changes of pressure i.e. liquid phase CO2 composition. High pressure phase equilibrium, high pressure NMR, and solid state NMR have been utilized to understand the separation phenomena. PMID:26159829

  18. Intermolecular forces in acetonitrile + ethanol binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Elangovan, A.; Shanmugam, R.; Arivazhagan, G.; Mahendraprabu, A.; Karthick, N. K.

    2015-10-01

    FTIR spectral measurements have been carried out on the binary mixtures of acetonitrile with ethanol at 1:0 (acetonitrile:ethanol), 1:1, 1:2, 1:3 and 0:1 at room temperature. DFT and isosurface calculations have been performed. The acetonitrile + ethanol binary mixtures consist of 1:1, 1:2, 1:3 and 1:4 complexes formed through both the red and blue shifting H-bonds. Inter as well as intra molecular forces are found to exist in 1:3 and 1:4 complexes.

  19. Nature of Mesoscopic Organization in Protic Ionic Liquid-Alcohol Mixtures.

    PubMed

    Schroer, Wolffram; Triolo, Alessandro; Russina, Olga

    2016-03-10

    The mesoscopic morphology of mixtures of ethylammonium nitrate, a protic ionic liquid, and n-pentanol is explored for the first time using small angle X-ray scattering as a function of concentration and temperature. Both compounds are amphiphilic and characterized by an extended hydrogen bonding network; however, though macroscopically homogeneous, their mixtures are highly heterogeneous at the mesoscopic spatial scales. Previous structural studies rationalized similar features in related mixtures proposing the existence of large aggregates or micelle- and/or microemulsion-like structures. Here we show that a detailed analysis of the present concentration and temperature resolved experimental data set supports a structural scenario where the mesoscopic heterogeneities are the due to density fluctuations that are precursors of liquid-liquid phase separation. Accordingly no existence of structurally organized aggregates (such as micellar or microemulsion aggregates) is required to account for the mesoscopic heterogeneities detected in this class of binary mixtures. PMID:26895177

  20. Nano bubbles in liquid of a noble-gas mixture.

    PubMed

    Yamamoto, Takenori; Ohnishi, Shuhei

    2010-02-01

    Large-scale molecular dynamics (MD) simulations with over one million atoms are used to investigate nano bubbles in Ar-Ne liquid. The simulations demonstrate cavitations in the stretched liquid, and bubble creation and collapse. We find that a small cavity created in the stretched liquid spontaneously transforms into a nano bubble with the homogeneous vapor region. The equilibrium spherical bubble of 11.4 nm in radius is obtained after the long-time MD run. The surface tension of the nano bubble is found to be larger than that of the flat surface.

  1. Liquid-phase dehydration of aqueous ethanol-gasoline mixtures

    SciTech Connect

    Fanta, G.F.; Burr, R.C.; Orton, W.L.; Doane, W.M.

    1980-11-07

    Two-phase mixtures of gasoline, water, and ethanol were dehydrated with both starch and saponified starch-g-polyacrylonitrile (HSPAN). Whereas starch absorbed ethanol as well as water, HSPAN selectively absorbed the water component, allowing ethanol to dissolve in the gasoline phase.

  2. Observation of crystallization slowdown in supercooled parahydrogen and orthodeuterium quantum liquid mixtures

    NASA Astrophysics Data System (ADS)

    Kühnel, Matthias; Fernández, José M.; Tramonto, Filippo; Tejeda, Guzmán; Moreno, Elena; Kalinin, Anton; Nava, Marco; Galli, Davide E.; Montero, Salvador; Grisenti, Robert E.

    2014-05-01

    We report a quantitative experimental study of the crystallization kinetics of supercooled quantum liquid mixtures of parahydrogen (pH2) and orthodeuterium (oD2) by high spatial resolution Raman spectroscopy of liquid microjets. We show that in a wide range of compositions the crystallization rate of the isotopic mixtures is significantly reduced with respect to that of the pure substances. To clarify this behavior we have performed path-integral simulations of the nonequilibrium pH2-oD2 liquid mixtures, revealing that differences in quantum delocalization between the two isotopic species translate into different effective particle sizes. Our results provide experimental evidence for crystallization slowdown of quantum origin, offering a benchmark for theoretical studies of quantum behavior in supercooled liquids.

  3. Low-temperature liquid-liquid extraction of phenols from aqueous solutions with hydrophilic mixtures of extractants

    NASA Astrophysics Data System (ADS)

    Rudakov, O. B.; Khorokhordina, E. A.; Preobrazhenskii, M. A.; Rudakova, L. V.

    2016-08-01

    The volume ratios in acetonitrile-ethyl acetate (90 : 10, 95 : 5), acetonitrile-isopropanol-ethyl acetate (70 : 15 : 15, 80 : 5 : 15), and isopropanol-1-butanol (50 : 50) mixtures were determined. Their mixing with water (1 : 1) and storage at-10°C led to partitioning into two immiscible liquid phases without formation of the ice phase. The mixtures were shown to be useful as hydrophilic extractants in low-temperature liquidliquid extraction of phenol from aqueous solutions.

  4. Estimation of Interfacial Tension between Organic Liquid Mixtures and Water

    SciTech Connect

    Yoon, Hongkyu; Oostrom, Martinus; Werth, Charles J.

    2009-10-15

    Knowledge of IFT values for chemical mixtures helps guide the design and analysis of various processes, including NAPL remediation with surfactants or alcohol flushing, enhanced oil recovery, and chemical separation technologies, yet available literature values are sparse. A comprehensive comparison of thermodynamic and empirical models for estimating interfacial tension (IFT) of organic chemical mixtures with water is conducted, mainly focusing on chlorinated organic compounds for 14 ternary, three quaternary, and one quinary systems. Emphasis is placed on novel results for systems with three and four organic chemical compounds, and for systems with composite organic compounds like lard oil and mineral oil. Seven models are evaluated: the ideal and nonideal monolayer models (MLID and MLNID), the ideal and nonideal mutual solubility models (MSID and MSNID), an empirical model for ternary systems (EM), a linear mixing model based on mole fractions (LMMM), and a newly developed linear mixing model based on volume fractions of organic mixtures (LMMV) for higher order systems. The two ideal models (MLID and MSID) fit ternary systems of chlorinated organic compounds without surface active compounds relatively well. However, both ideal models did not perform well for the mixtures containing a surface active compound. However, for these systems, both the MLNID and MSNID models matched the IFT data well. It is shown that the MLNID model with a surface coverage value (0.00341 mmol/m2) obtained in this study can practically be used for chlorinated organic compounds. The LMMM results in poorer estimates of the IFT as the difference in IFT values of individual organic compounds in a mixture increases. The EM, with two fitting parameters, provided accurate results for all 14 ternary systems including composite organic compounds. The new LMMV method for quaternary and higher component systems was successfully tested. This study shows that the LMMV may be able to be used for

  5. Solid–liquid equilibria of binary mixtures of fluorinated ionic liquids†

    PubMed Central

    Teles, Ana Rita R.; Correia, Helga; Maximo, Guilherme J.; Rebelo, Luís P. N.; Freire, Mara G.; Pereiro, Ana B.; Coutinho, João A. P.

    2016-01-01

    Within ionic liquids, fluorinated ionic liquids (FILs) present unique physico-chemical properties and potential applications in several fields. However, the melting point of these neoteric compounds is usually higher due to the presence of fluorine atoms. This drawback may be resolved by, for instance, mixing different FILs to create eutectic mixtures. In this work, binary mixtures of fluoro-containing and fluorinated ionic liquids were considered with the aim of decreasing their melting temperatures as well as understanding and characterizing these mixtures and their phase transitions. Five FILs were selected, allowing the investigation of four binary mixtures, each of them with a common ion. Their solid–liquid and solid–solid equilibria were studied by differential scanning calorimetry and the non-ideality of the mixtures was investigated. Overall, a variety of solid–liquid equilibria with systems exhibiting eutectic behavior, polymorphs with solid–solid phase transitions, and the formation of intermediate compounds and solid solutions were surprisingly found. In addition to these intriguing behaviours, novel FILs with lower melting temperatures were obtained by the formation of binary systems, thus enlarging the application range of FILs at lower temperatures. PMID:27603428

  6. Unusual liquid-liquid phase transition in aqueous mixtures of a well-known dendrimer.

    PubMed

    da Costa, Viviana C P; Annunziata, Onofrio

    2015-11-21

    Liquid-liquid phase separation (LLPS) has been extensively investigated for polymer and protein solutions due to its importance in mixture thermodynamics, separation science and self-assembly processes. However, to date, no experimental studies have been reported on LLPS of dendrimer solutions. Here, it is shown that LLPS of aqueous solutions containing a hydroxyl-functionalized poly(amido amine) dendrimer of fourth generation is induced in the presence of sodium sulfate. Both the LLPS temperature and salt-dendrimer partitioning between the two coexisting phases at constant temperature were measured. Interestingly, our experiments show that LLPS switches from being induced by cooling to being induced by heating as the salt concentration increases. The two coexisting phases also show opposite temperature response. Thus, this phase transition exhibits a simultaneous lower and upper critical solution temperature-type behavior. Dynamic light-scattering and dye-binding experiments indicate that no appreciable conformational change occurs as the salt concentration increases. To explain the observed phase behavior, a thermodynamic model based on two parameters was developed. The first parameter, which describes dendrimer-dendrimer interaction energy, was determined by isothermal titration calorimetry. The second parameter describes the salt salting-out strength. By varying the salting-out parameter, it is shown that the model achieves agreement not only with the location of the experimental binodal at 25 °C but also with the slope of this curve around the critical point. The proposed model also predicts that the unusual temperature behavior of this phase transition can be described as the net result of two thermodynamic factors with opposite temperature responses: salt thermodynamic non-ideality and salting-out strength.

  7. Unusual liquid-liquid phase transition in aqueous mixtures of a well-known dendrimer.

    PubMed

    da Costa, Viviana C P; Annunziata, Onofrio

    2015-11-21

    Liquid-liquid phase separation (LLPS) has been extensively investigated for polymer and protein solutions due to its importance in mixture thermodynamics, separation science and self-assembly processes. However, to date, no experimental studies have been reported on LLPS of dendrimer solutions. Here, it is shown that LLPS of aqueous solutions containing a hydroxyl-functionalized poly(amido amine) dendrimer of fourth generation is induced in the presence of sodium sulfate. Both the LLPS temperature and salt-dendrimer partitioning between the two coexisting phases at constant temperature were measured. Interestingly, our experiments show that LLPS switches from being induced by cooling to being induced by heating as the salt concentration increases. The two coexisting phases also show opposite temperature response. Thus, this phase transition exhibits a simultaneous lower and upper critical solution temperature-type behavior. Dynamic light-scattering and dye-binding experiments indicate that no appreciable conformational change occurs as the salt concentration increases. To explain the observed phase behavior, a thermodynamic model based on two parameters was developed. The first parameter, which describes dendrimer-dendrimer interaction energy, was determined by isothermal titration calorimetry. The second parameter describes the salt salting-out strength. By varying the salting-out parameter, it is shown that the model achieves agreement not only with the location of the experimental binodal at 25 °C but also with the slope of this curve around the critical point. The proposed model also predicts that the unusual temperature behavior of this phase transition can be described as the net result of two thermodynamic factors with opposite temperature responses: salt thermodynamic non-ideality and salting-out strength. PMID:26451401

  8. On the collective network of ionic liquid/water mixtures. IV. Kinetic and rotational depolarization.

    PubMed

    Schröder, Christian; Sega, Marcello; Schmollngruber, Michael; Gailberger, Elias; Braun, Daniel; Steinhauser, Othmar

    2014-05-28

    Dielectric spectroscopy is a measure of the collective Coulomb interaction in liquid systems. Adding ionic liquids to an aqueous solution results in a decrease of the static value of the generalized dielectric constant which cannot be attributed to kinetic depolarization models characterized by the static conductivity and rotational relaxation constant. However, a dipolar Poisson-Boltzmann model computing the water depolarization in the proximity of ions is not only successful for simple electrolytes but also in case of molecular ionic liquids. Moreover, our simple geometric hydration model is also capable to explain the dielectric depolarization. Both models compute the dielectric constant of water and obtain the overall dielectric constant by averaging the values of its components, water and the ionic liquid, weighted by their volume occupancies. In this sense, aqueous ionic liquid mixtures seem to behave like polar mixtures.

  9. Experimental study of heat conductivity of n-heptane-n-octane-isooctane liquid ternary mixtures at high pressure

    SciTech Connect

    Naziev, D.Ya.

    1994-03-20

    Heat conductivity of liquid ternary mixtures of various compositions at various pressures and temperatures was experimentally studied. Dependence of heat conductivities of ternary mixtures on concentration of components was established. An equation linking the heat conductivities of ternary mixtures through those of pure components and appropriate binary mixtures was proposed.

  10. Hazards Induced by Breach of Liquid Rocket Fuel Tanks: Conditions and Risks of Cryogenic Liquid Hydrogen-Oxygen Mixture Explosions

    NASA Technical Reports Server (NTRS)

    Osipov, Viatcheslav; Muratov, Cyrill; Hafiychuk, Halyna; Ponizovskya-Devine, Ekaterina; Smelyanskiy, Vadim; Mathias, Donovan; Lawrence, Scott; Werkheiser, Mary

    2011-01-01

    We analyze the data of purposeful rupture experiments with LOx and LH2 tanks, the Hydrogen-Oxygen Vertical Impact (HOVI) tests that were performed to clarify the ignition mechanisms, the explosive power of cryogenic H2/Ox mixtures under different conditions, and to elucidate the puzzling source of the initial formation of flames near the intertank section during the Challenger disaster. We carry out a physics-based analysis of general explosions scenarios for cryogenic gaseous H2/Ox mixtures and determine their realizability conditions, using the well-established simplified models from the detonation and deflagration theory. We study the features of aerosol H2/Ox mixture combustion and show, in particular, that aerosols intensify the deflagration flames and can induce detonation for any ignition mechanism. We propose a cavitation-induced mechanism of self-ignition of cryogenic H2/Ox mixtures that may be realized when gaseous H2 and Ox flows are mixed with a liquid Ox turbulent stream, as occurred in all HOVI tests. We present an overview of the HOVI tests to make conclusion on the risk of strong explosions in possible liquid rocket incidents and provide a semi-quantitative interpretation of the HOVI data based on aerosol combustion. We uncover the most dangerous situations and discuss the foreseeable risks which can arise in space missions and lead to tragic outcomes. Our analysis relates to only unconfined mixtures that are likely to arise as a result of liquid propellant space vehicle incidents.

  11. Phase diagrams of mixtures of a polymer and a cholesteric liquid crystal under an external field.

    PubMed

    Matsuyama, Akihiko

    2014-11-14

    We present a mean field theory to describe phase behaviors in mixtures of a polymer and a cholesteric liquid crystal under an external magnetic or electric field. Taking into account a chiral coupling between a polymer and a liquid crystal under the external field, we examine twist-untwist phase transitions and phase separations in the mixtures. It is found that a cholesteric-nematic phase transition can be induced by not only the external field but also concentration and temperature. Depending on the strength of the external field, we predict cholesteric-paranematic (Ch+pN), nematic-paranematic (N+pN), cholesteric-nematic (Ch+N) phase separations, etc., on the temperature-concentration plane. We also discuss mixtures of a non-chiral nematic liquid crystal and a chiral dopant. PMID:25399158

  12. Vapor-liquid equilibria of binary mixtures containing methane, ethane, and carbon dioxide from molecular simulation

    NASA Astrophysics Data System (ADS)

    Vrabec, J.; Fischer, J.

    1996-07-01

    The NpT + test particle method is used in order to predict vapor-liquid equilibria of the mixtures methane + ethane, methane + carbon dioxide, and carbon dioxide +ethane by molecular simulations. The pure-component molecular models were fitted to the experimental vapor pressures and saturated liquid densities in previous papers, which used the same simulation method for the determination of the phase equilibria. For each binary mixture the two unlike interaction parameters were determined from one experimental excess volume and one excess enthalpy. Based on these molecular models the vapor-liquid phase equilibria were calculated for each mixture at three temperatures. Comparison of the pressure-composition data with experimental results shows the high predictive power of this molecular based procedure. This statement is confirmed by additional comparisons of the pressure-composition diagrams and the pressure-density diagrams with results from equations of state.

  13. Phase diagrams of mixtures of a polymer and a cholesteric liquid crystal under an external field

    SciTech Connect

    Matsuyama, Akihiko

    2014-11-14

    We present a mean field theory to describe phase behaviors in mixtures of a polymer and a cholesteric liquid crystal under an external magnetic or electric field. Taking into account a chiral coupling between a polymer and a liquid crystal under the external field, we examine twist-untwist phase transitions and phase separations in the mixtures. It is found that a cholesteric-nematic phase transition can be induced by not only the external field but also concentration and temperature. Depending on the strength of the external field, we predict cholesteric-paranematic (Ch+pN), nematic-paranematic (N+pN), cholesteric-nematic (Ch+N) phase separations, etc., on the temperature-concentration plane. We also discuss mixtures of a non-chiral nematic liquid crystal and a chiral dopant.

  14. Dissociation of equimolar mixtures of aqueous carboxylic acids in ionic liquids: role of specific interactions.

    PubMed

    Shukla, Shashi Kant; Kumar, Anil

    2015-04-30

    Hammett acidity function observes the effect of protonation/deprotonation on the optical density/absorbance of spectrophotometric indicator. In this work, the Hammett acidity, H0, of equimolar mixtures of aqueous HCOOH, CH3COOH, and CH3CH2COOH was measured in 1-methylimidazolium-, 1-methylpyrrolidinium-, and 1-methylpiperidinium-based protic ionic liquids (PILs) and 1-butyl-3-methylimidazolium-based aprotic ionic liquid (AIL) with formate (HCOO(-)) anion. Higher H0 values were observed for the equimolar mixtures of aqueous carboxylic acids in protic ionic liquids compared with those of the aprotic ionic liquid because of the involvement of the stronger specific interactions between the conjugate acid of ionic liquid and conjugate base of carboxylic acids as suggested by the hard-soft acid base (HSAB) theory. The different H0 values for the equimolar mixtures of aqueous carboxylic acids in protic and aprotic ionic liquids were noted to depend on the activation energy of proton transfer (Ea,H(+)). The higher activation energy of proton transfer was obtained in AIL, indicating lower ability to form specific interactions with solute than that of PILs. Thermodynamic parameters determined by the "indicator overlapping method" further confirmed the involvement of the secondary interactions in the dissociation of carboxylic acids. On the basis of the thermodynamic parameter values, the potential of different ionic liquids in the dissociation of carboxylic acids was observed to depend on the hydrogen bond donor acidity (α) and hydrogen bond acceptor basicity (β), characteristics of specific interactions.

  15. A non-equilibrium state diagram for liquid/fluid/particle mixtures.

    PubMed

    Velankar, Sachin S

    2015-11-21

    The equilibrium structures of ternary oil/water/surfactant systems are often represented within a triangular composition diagram with various regions of the triangle corresponding to different equilibrium states. We transplant this idea to ternary liquid/fluid/particle systems that are far from equilibrium. Liquid/liquid/particle mixtures or liquid/gas/particle mixtures yield a wide diversity of morphologies including Pickering emulsions, bijels, pendular aggregates, spherical agglomerates, capillary suspensions, liquid marbles, powdered liquids, and particle-stabilized foams. This paper argues that such ternary liquid/fluid/particle mixtures can be unified into a non-equilibrium state diagram. What is common among all these systems is that the morphology results from an interplay between the preferential wettability of the particles, capillarity, and viscous forces encountered during mixing. Therefore all such systems share certain universal features, regardless of the details of the particles or fluids used. These features guide the construction of a non-equilibrium state diagram which takes the form of a triangular prism, where each triangular cross-section of the prism corresponds to a different relative affinity of the particles towards the two fluids. We classify the prism into regions in which the various morphologies appear and also emphasize the major difference between systems in which the particles are fully-wetted by one of the fluids vs. partially-wetted by both fluids. We also discuss how the state diagram may change with mixing intensity or with interparticle attractions.

  16. Velocity of large bubble in liquid-solid mixture in a vertical tube

    SciTech Connect

    Hamaguchi, H.; Sakaguchi, T.

    1995-09-01

    The upward movement of a large bubble in a stationary mixture of liquid and solid is one of the most fundamental phenomena of gas-liquid-solid three phase slug flow in a vertical tube. The purpose of this study is to make clear the characteristic of the rising velocity of this fundamental flow experimentally. The rising velocity of a large bubble V in a liquid-solid mixture was measured and compared with the velocity V{sub o} in a liquid (without solid). The experimental results were correlated using a non-dimensional velocity V{sup *}(=V/V{sub o}), and the following results were obtained. It was found that the characteristic of the rising velocity differs according to the tube diameter and the liquid viscosity, or the Galileo number in the non-dimensional expression. It can be classified into two regimes. (i) When the liquid viscosity is large (or the tube diameter is small), V{sup *} decreases linearly against the volumetric solid fraction {epsilon} of the mixture. (ii) When the viscosity is small, on the other hand, the relation between V{sup *} and {epsilon} is not linear. This classification can be explained by the results in the previous papers by the authors dealing with a large bubble in a liquid.

  17. Induced stabilization of columnar phases in binary mixtures of discotic liquid crystals.

    PubMed

    Cienega-Cacerez, Octavio; García-Alcántara, Consuelo; Moreno-Razo, José Antonio; Díaz-Herrera, Enrique; Sambriski, Edward John

    2016-01-28

    Three discotic liquid-crystalline binary mixtures, characterized by their extent of bidispersity in molecular thickness, were investigated with molecular dynamics simulations. Each equimolar mixture contained A-type (thin) and B-type (thick) discogens. The temperature-dependence of the orientational order parameter reveals that A-type liquid samples produce ordered phases more readily, with the (hexagonal) columnar phase being the most structured variant. Moderately and strongly bidisperse mixtures produce globally-segregated samples for temperatures corresponding to ordered phases; the weakly bidisperse mixture displays microheterogeneities. Ordered phases in the B-type liquid are induced partially by the presence of the A-type fluid. In the moderately bidisperse mixture, order is induced through orientational frustration: a mixed prenematic-like phase precedes global segregation to yield nematic and columnar mesophases upon further cooling. In the strongly bidisperse mixture, order is induced less efficiently through a paranematic-like mechanism: a highly-ordered A-type fluid imparts order to B-type discogens found at the interface of a fully-segregated sample. This ordering effect permeates into the disordered B-type domain until nematic and columnar phases emerge upon further cooling. At sufficiently low temperatures, all samples investigated exhibit the (hexagonal) columnar mesophase.

  18. Thermal and Optical Properties of Some Hydrogen-Bonded Liquid Crystal Mixtures

    NASA Astrophysics Data System (ADS)

    Okumuş, Mustafa; Özgan, Şükrü; Yılmaz, Süleyman

    2014-08-01

    Phase transition properties of the mixtures of hydrogen-bonded nematic liquid crystals (HBLC) 4-hexylbenzoic acid (6BA), 4-(octyloxy)benzoic acid (8OBA), and 4-(decyloxy)benzoic acid (10OBA) have been investigated by means of differential scanning calorimetry (DSC) and polarize optic microscope (POM). The DSC and POM results clearly indicate the existence of smectic and nematic phase transitions in binary mixtures. The phase transition temperature values of 6BA/10OBA mixtures have clearly increased with increasing heating rate. The activation energies were calculated for the phase transitions of 6BA/10OBA liquid crystal (LC) mixture. The optical transmittance of these mixed hydrogen-bonded nematic liquid crystals was investigated in terms of temperature variations through electrooptic methods. The electrooptic experiments indicate that, while low in the nematic phase, the optical transmittance is very high at the nematic-isotropic phase transition. The transmitted light intensity values of 6BA/8OBA mixture are somewhat higher than those of other binary mixtures, 6BA/10OBA and 8OBA/10OBA, a result associated with the different alkyloxy chain lengths.

  19. Producing liquid-solid mixtures (slushes) of oxygen or hydrogen using an auger

    NASA Astrophysics Data System (ADS)

    Voth, R. O.

    An auger rotating inside a brass tube refrigerated with liquid helium was used to produce liquid-solid (slush) mixtures of hydrogen and of oxygen. The auger produced small particles from the cryogens so that the resulting slush mixture could be transferred and stored. The auger could produce slush continuously in an appropriate system; it could produce slush at pressures higher than the triple point pressure of the cryogen, and the energy required to produce the slush was less than the energy required to produce slush using the freeze-thaw process.

  20. Optical studies on smectic phases in binary mixture of liquid crystals

    NASA Astrophysics Data System (ADS)

    Govindaiah, T. N.; Sreepad, H. R.; Nagaraja, N.; Sridhara, G. R.; Ravi, H. R.

    2015-06-01

    The binary mixture of two non-mesogenic compounds viz., Didodecyl dimethyl ammonium bromide (DDAB) and ethylene glycol (EG) exhibits different liquid crystalline phase's at large range of concentrations and temperature. The concentrations with lower / higher percentage of DDAB exhibit I-SmA-SmC*-SmE-K sequentially when the specimen is cooled from isotropic phase. Different liquid crystalline phases observed in the mixture were studied using DSC, X-ray, and Optical microscopic techniques. The temperature variations of optical anisotropy have also been discussed.

  1. Molecular dynamics simulations of the structural and thermodynamic properties of imidazolium-based ionic liquid mixtures.

    PubMed

    Méndez-Morales, T; Carrete, J; Cabeza, O; Gallego, L J; Varela, L M

    2011-09-29

    In this work, extensive molecular dynamics simulations of mixtures of alcohols of several chain lengths (methanol and ethanol) with the ionic liquids (ILs) composed of the cation 1-hexyl-3-methylimidazolium and several anions of different hydrophobicity degrees (Cl(-), BF(4)(-), PF(6)(-)) are reported. We analyze the influence of the nature of the anion, the length of the molecular chain of the alcohol, and the alcohol concentration on the thermodynamic and structural properties of the mixtures. Densities, excess molar volumes, total and partial radial distribution functions, coordination numbers, and hydrogen bond degrees are reported and analyzed for mixtures of the ILs with methanol and ethanol. The aggregation process is shown to be highly dependent on the nature of the anion and the size of the alcohol, since alcohol molecules tend to interact predominantly with the anionic part of the IL, especially in mixtures of the halogenated IL with methanol. Particularly, our results suggest that the formation of an apolar network similar to that previously reported in mixtures of ILs with water does not take place in mixtures with alcohol when the chloride anion is present, the alcohol molecules being instead homogeneously distributed in the polar network of IL. Moreover, the alcohol clusters formed in mixtures of [HMIM][PF(6)] with alcohol were found to have a smaller size than in mixtures with water. Additionally, we provide a semiquantitative analysis of the dependence of the hydrogen bonding degree of the mixtures on the alcohol concentration.

  2. Protonic Ammonium Nitrate Ionic Liquids and Their Mixtures: Insights into Their Thermophysical Behavior.

    PubMed

    Canongia Lopes, José N; Esperança, José M S S; de Ferro, André Mão; Pereiro, Ana B; Plechkova, Natalia V; Rebelo, Luis P N; Seddon, Kenneth R; Vázquez-Fernández, Isabel

    2016-03-10

    This study is centered on the thermophysical characterization of different families of alkylammonium nitrate ionic liquids and their binary mixtures, namely the determination at atmospheric pressure of densities, electric conductivities and viscosities in the 288.15 < T/K < 353.15 range. First, measurements focusing on ethylammonium, propylammonium and butylammonium nitrate systems, and their binary mixtures, were determined. These were followed by studies involving binary mixtures composed of ethylammonium nitrate (with three hydrogen bond donor groups) and different homologous ionic liquids with differing numbers of hydrogen bond donor groups: diethylammonium nitrate (two hydrogen bond donors), triethylammonium nitrate (one hydrogen bond donor) and tetraethylammonium nitrate (no hydrogen bond donors). Finally, the behavior of mixtures with different numbers of equivalent carbon atoms in the alkylammonium cations was analyzed. The results show a quasi-ideal behavior for all monoalkylammonium nitrate mixtures. In contrast, the other mixtures show deviations from ideality, namely when the difference in the number of carbon atoms present in the cations increases or the number of hydrogen bond donors present in the cation decreases. Overall, the results clearly show that, besides the length and distribution of alkyl chains present in a cation such as alkylammonium, there are other structural and interaction parameters that influence the thermophysical properties of both pure compounds and their mixtures.

  3. Tunable pattern transitions in a liquid-crystal-monomer mixture using two-photon polymerization.

    PubMed

    Jisha, Chandroth P; Hsu, Kuei-Chu; Lin, Yuanyao; Lin, Ja-Hon; Jeng, Chien-Chung; Lee, Ray-Kuang

    2012-12-01

    Through two-photon lithographic processes, we report experimentally and numerically a series of photoinduced tunable polymerization patterns in shapes from straight channel, serpentine curve, to periodic grating when an ultrashort femtosecond laser pulse directly writes in a liquid-crystal-monomer mixture along a line for different scanning speeds. Laser beams with polarization perpendicular to the direction of writing and the alignment of liquid crystals, produce snake-shaped patterns at an intermediate scan rate. PMID:23202094

  4. Prediction of acute toxicity of chemicals in mixtures: worms Tubifex tubifex and gas/liquid distribution.

    PubMed

    Tichý, M; Borek-Dohalský, V; Matousová, D; Rucki, M; Feltl, L; Roth, Z

    2002-03-01

    The aim of this contribution is to support our proposal of the procedure for predicting acute toxicity of binary mixtures by QSAR analysis techniques. The changes of a mixture composition are described by molar ratio R and visualized in the R-plot (QCAR--quantitative composition-activity relationships). The approach was inspired by Rault and Dalton's laws, their positive and negative deviations in the behavior of a mixture of real gases, by Loewe and Muischnek isoboles and by the Finney test of additivity. Acute toxicity was determined by the laboratory test with woms Tubifex tubifex. The additivity of the acute toxicity in the binary mixture benzene + nitrobenzene was confirmed and a new interaction is described: "mixed interaction" with the binary mixture aniline + ethanol. The "mixed interaction" means that depending on mixture composition, both potentiation and inhibition can occur. As the first physicochemical descriptor of the changes caused by the changing composition of binary mixtures, the gas/liquid equilibrium was studied and a composition of the gaseous phase was determined by a gas chromatographic method. The method for determination of concentrations in the gaseous phase was described. The gaseous phase composition of benzene + nitrobenzene. benzene + ethanol, benzene + aniline and ethanol + aniline mixtures was analyzed. It was found that if the concentrations of the mixture's components in the gaseous phase behave nonideally (they are not additive), the acute toxicity of the same mixture is not additive as well. Another descriptor to distinguish between potentiation and inhibition will be, however, necessary. The properties, both gaseous phase composition and the acute toxicity, of the benzene + nitrobenzene mixture are additive. In mixtures with the mixed interaction, the R-plot of the composition of the gaseous phase is complex with a large variation of results.

  5. Molecular dynamics simulations of mixtures of protic and aprotic ionic liquids.

    PubMed

    Docampo-Álvarez, Borja; Gómez-González, Víctor; Méndez-Morales, Trinidad; Rodríguez, Julio R; López-Lago, Elena; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M

    2016-09-14

    Molecular dynamics simulations of mixtures of the protic ionic liquid ethylammonium nitrate (EAN) and the aprotic 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) are reported and the results are compared with experimental density and electrical conductivity measurements. Essentially ideal mixing of the ionic liquids is seen to take place by means of experimental and simulated excess molar volumes, whose very low values suggest a gradual transition between the structures of the two end constituents of the mixture. A weak dominance of the structure of the protic ionic liquid is nevertheless registered, due to a slight preferential formation of the network of hydrogen bonds, as reflected in the coordination number and the number of hydrogen bonds in the mixture. A novel conductivity curve showing pronounced deviations from the simple ideal mixing rule is reported, with three different regions defined by a local maximum - reflecting enhanced translational dynamics relative to ideal mixture behaviour - and a global minimum at intermediate concentrations. The physical origin of this behaviour is discussed along with the structure and single-particle dynamics of the mixture, and it is seen that these regions are defined by the onset of the formation of the EAN hydrogen bonded network (xEAN = 0.2) and the virtual disappearance of the structure of the aprotic ionic liquid at xEAN = 0.7. It is concluded that the delicate interplay between both networks has a deep effect on the placement and mobility of [EMIM](+) cations in the mixture all throughout the different stages of the structural transition, which seems to be the driving force behind the reported transport properties of the mixture at intermediate to high EAN concentrations.

  6. Liquid chromatographic fractionations of mixtures of polystyrene oligomers

    SciTech Connect

    Curtis, M A; Webb, J W; Warren, D C; Brandt, V O; Gerberich, F G; Raut, K B; Rogers, L B

    1980-05-24

    Oligomer mixtures of 800, 2200, and 4000 molecular weight polystyrene have been fractionated using silica and bonded phase columns under similar conditions of solvent gradient and flow rate. Using a hexane/tetrahydrofuran gradient, the silica and nitro phases were best in that they separated 41 and 43 oligomers, respectively. At the other extreme, a phenyl bonded phase column gave virtually no resolution using a water/THF gradient and a cyano bonded phase column, using the earlier hexane/tetrahydrofuran system, resolved only 10 oligomers. Amino and octadecyl bonded phase columns gave results intermediate between these two extremes. The strength of the solvent used to dissolve the sample was found to be of critical importance. Use of too good a sample solvent seriously degraded the attainable resolution. When number average and weight average molecular weights for an 800 molecular weight polystyrene sample were calculated from the oligomer distribution, the silica column gave values which were most consistent with those reported from other methods.

  7. Nonaqueous Phase Liquid Dissolution in Porous Media: Multi-Scale Effects of Multi-Component Dissolution Kinetics on Cleanup Time

    SciTech Connect

    McNab, W; Ezzedine, S; Detwiler, R

    2007-02-26

    Industrial organic solvents such as trichloroethylene (TCE) and tetrachloroethylene (PCE) constitute a principal class of groundwater contaminants. Cleanup of groundwater plume source areas associated with these compounds is problematic, in part, because the compounds often exist in the subsurface as dense nonaqueous phase liquids (DNAPLs). Ganglia (or 'blobs') of DNAPL serve as persistent sources of contaminants that are difficult to locate and remediate (e.g. Fenwick and Blunt, 1998). Current understanding of the physical and chemical processes associated with dissolution of DNAPLs in the subsurface is incomplete and yet is critical for evaluating long-term behavior of contaminant migration, groundwater cleanup, and the efficacy of source area cleanup technologies. As such, a goal of this project has been to contribute to this critical understanding by investigating the multi-phase, multi-component physics of DNAPL dissolution using state-of-the-art experimental and computational techniques. Through this research, we have explored efficient and accurate conceptual and numerical models for source area contaminant transport that can be used to better inform the modeling of source area contaminants, including those at the LLNL Superfund sites, to re-evaluate existing remediation technologies, and to inspire or develop new remediation strategies. The problem of DNAPL dissolution in natural porous media must be viewed in the context of several scales (Khachikian and Harmon, 2000), including the microscopic level at which capillary forces, viscous forces, and gravity/buoyancy forces are manifested at the scale of individual pores (Wilson and Conrad, 1984; Chatzis et al., 1988), the mesoscale where dissolution rates are strongly influenced by the local hydrodynamics, and the field-scale. Historically, the physico-chemical processes associated with DNAPL dissolution have been addressed through the use of lumped mass transfer coefficients which attempt to quantify the

  8. Bubbling behaviors induced by gas-liquid mixture permeating through a porous medium

    NASA Astrophysics Data System (ADS)

    Hu, Liang; Li, Mingbo; Chen, Wenyu; Xie, Haibo; Fu, Xin

    2016-08-01

    This paper investigates the bubbling behaviors induced by gas-liquid mixture permeating through porous medium (PM), which was observed in developing immersion lithography system and was found having great differences with traditional bubbling behaviors injected with only gas phase through the PM. An experimental setup was built up to investigate the bubbling characteristics affected by the mixed liquid phase. Both the flow regimes of gas-liquid mixture in micro-channel (upstream of the PM) and the bubbling flow regimes in water tank (downstream of the PM) were recorded synchronously by high-speed camera. The transitions between the flow regimes are governed by gas and liquid Weber numbers. Based on the image analysis, the characteristic parameters of bubbling region, including the diameter of bubbling area on PM surface, gas-phase volume flux, and dispersion angle of bubbles in suspending liquid, were studied under different proportions of gas and liquid flow rate. Corresponding empirical correlations were developed to describe and predict these parameters. Then, the pertinent bubble characteristics in different bubbling flow regimes were systematically investigated. Specifically, the bubble size distribution and the Sauter mean diameter affected by increasing liquid flow rate were studied, and the corresponding analysis was given based on the hydrodynamics of bubble-bubble and bubble-liquid interactions. According to dimensionless analysis, the general prediction equation of Sauter mean diameter under different operating conditions was proposed and confirmed by experimental data. The study of this paper is helpful to improve the collection performance of immersion lithography and aims to reveal the differences between the bubbling behaviors on PM caused by only gas flow and gas-liquid mixture flow, respectively, for the researches of fluid flow.

  9. Thermocapillary migration of droplets in a transparent liquid mixture and a monotectic alloy melt

    NASA Astrophysics Data System (ADS)

    Klein, H.; Neumann, H.

    2003-08-01

    Experimental evidence of thermocapillary migration of droplets is reported in two different systems, a binary liquid mixture with miscibility gap and a monotectic alloy belt. Thermocapillary migration is monitored by video microscopy in the first and by using electrical resistance measurements in the second system.

  10. Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

    ERIC Educational Resources Information Center

    Tasic, Aleksandar Z.; Djordjevic, Bojan D.

    1983-01-01

    Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…

  11. Spectroscopic and thermodynamic properties of hydrogen bonded water molecules in binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Bricknell, B. C.; Ford, T. A.; Letcher, T. M.

    1997-03-01

    Some relationships have been found between the infrared spectroscopic properties of water molecules hydrogen bonded to a number of bases in binary liquid mixtures, and the partial eolar excess enthalpies at infinite dilution of water of the solutions. The results suggest a new approach to the use of the well-known Badger-Bauer relationship.

  12. Two-phase turbine engines. [using gas-liquid mixture accelerated in nozzles

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.; Hays, L. G.

    1976-01-01

    A description is given of a two-phase turbine which utilizes a uniform mixture of gas and liquid accelerated in nozzles of the types reported by Elliott and Weinberg (1968). The mixture acts directly on an axial flow or tangential impulse turbine or is separated into gas and liquid streams which operate separately on a gas turbine and a hydraulic turbine. The basic two-phase cycles are examined, taking into account working fluids, aspects of nozzle expansion, details of turbine cycle operation, and the effect of mixture ratio variation. Attention is also given to two-phase nozzle efficiency, two-phase turbine operating characteristics and efficiencies, separator turbines, and impulse turbine experiments.

  13. Acoustic and Thermodynamic Properties of the Binary Liquid Mixture n-Octane + n-Dodecane

    NASA Astrophysics Data System (ADS)

    Khasanshin, T. S.; Golubeva, N. V.; Samuilov, V. S.; Shchemelev, A. P.

    2014-01-01

    The velocity of sound in the binary liquid mixture n-octane + n-dodecane has been investigated by the method of direct measurement of the pulse-transmission time in the interval of temperatures 298-433 K and pressures 0.1-100.1 MPa. The maximum measurement error amounts to 0.1%. The density, isobaric expansion coefficient, isobaric and isochoric heat capacities, and isothermal compressibility of a mixture of three compositions have been determined in the intervals of temperatures 298-393 K and pressures 0.1-100 MPa from the data on the velocity of sound. Also, the excess molar volume, the excess isothermal compressibility, and the deviation of the velocity of sound from its value for an ideal liquid have been determined. The coefficients of the Tate equation have been computed in the above temperature interval. A table of thermodynamic properties of the mixture has been presented.

  14. Glyme-lithium salt equimolar molten mixtures: concentrated solutions or solvate ionic liquids?

    PubMed

    Ueno, Kazuhide; Yoshida, Kazuki; Tsuchiya, Mizuho; Tachikawa, Naoki; Dokko, Kaoru; Watanabe, Masayoshi

    2012-09-13

    To demonstrate a new family of ionic liquids (ILs), i.e., "solvate" ionic liquids, the properties (thermal, transport, and electrochemical properties, Lewis basicity, and ionicity) of equimolar molten mixtures of glymes (triglyme (G3) and tetraglyme (G4)) and nine different lithium salts (LiX) were investigated. By exploring the anion-dependent properties and comparing them with the reported data on common aprotic ILs, two different classes of liquid regimes, i.e., ordinary concentrated solutions and "solvate" ILs, were found in the glyme-Li salt equimolar mixtures ([Li(glyme)]X) depending on the anionic structures. The class a given [Li(glyme)]X belonged to was governed by competitive interactions between the glymes and Li cations and between the counteranions (X) and Li cations. [Li(glyme)]X with weakly Lewis basic anions can form long-lived [Li(glyme)](+) complex cations. Thus, they behaved as typical ionic liquids. The lithium "solvate" ILs based on [Li(glyme)]X have many desirable properties for lithium-conducting electrolytes, including high ionicity, a high lithium transference number, high Li cation concentration, and high oxidative stability, in addition to the common properties of ionic liquids. The concept of "solvate" ionic liquids can be utilized in an unlimited number of combinations of other metal salts and ligands, and will thus open a new field of research on ionic liquids.

  15. Ionic liquids and deep eutectic solvents in natural products research: mixtures of solids as extraction solvents.

    PubMed

    Dai, Yuntao; van Spronsen, Jaap; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae

    2013-11-22

    Mixtures of solid chemicals may become liquid under certain conditions. These liquids are characterized by the formation of strong ionic (ionic liquids) or hydrogen bonds (deep eutectic solvents). Due to their extremely low vapor pressure, they are now widely used in polymer chemistry and synthetic organic chemistry, yet little attention has been paid to their use as extraction solvents of natural products. This review summarizes the preparation of ionic liquids and deep eutectic solvents with natural product components and recent progress in their applications to the extraction and analysis of natural products as well as the recovery of extracted compounds from their extracts. Additionally, various factors affecting extraction features of ionic liquids and deep eutectic solvents, as well as potential useful technologies including microwave and ultrasound to increase the extraction efficiency, are discussed.

  16. Phase equilibrium calculations of ternary liquid mixtures with binary interaction parameters and molecular size parameters determined from molecular dynamics.

    PubMed

    Oh, Suk Yung; Bae, Young Chan

    2010-07-15

    The method presented in this paper was developed to predict liquid-liquid equilibria in ternary liquid mixtures by using a combination of a thermodynamic model and molecular dynamics simulations. In general, common classical thermodynamic models have many parameters which are determined by fitting a model with experimental data. This proposed method, however, provides a simple procedure for calculating liquid-liquid equilibria utilizing binary interaction parameters and molecular size parameters determined from molecular dynamics simulations. This method was applied to mixtures containing water, hydrocarbons, alcohols, chlorides, ketones, acids, and other organic liquids over various temperature ranges. The predicted results agree well with the experimental data without the use of adjustable parameters.

  17. Phase equilibria of binary liquid crystal mixtures involving induced ordered phases

    NASA Astrophysics Data System (ADS)

    Huang, Tsang-Min

    A phenomenological model for elucidating phase diagrams of hexagonal columnar/nematic liquid crystal mixtures has been developed on the basis of the combination of the Flory-Huggins (FH) free energy of isotropic mixing, Maier-Saupe (MS) free energy for nematic ordering, and Chandrasekhar-Clark free energy for hexagonal ordering. Self-consistent calculations show the theory is capable of predicting the various phase diagrams, covering nematic, hexagonal columnar, and isotropic phases. The model has been tested with the eutectic phase diagram of hexagonal columnar liquid crystal, 2, 3, 6, 7, 10, 11-hexapentyloxy triphenylene (HPTP)/reactive nematic mesogens, 4-(3-acryloyloxypropyloxy)-benzoic acid 2-methyl-1, 4-phenylene ester (RM257) mixtures determined by using DSC, polarized optical microscope (POM), and wide-angle X-ray diffraction (WAXD). The self-consistent calculation displays isotropic (I), nematic (N), hexagonal columnar (Colh), N + I, and Colh + I, and Colh + N coexistence regions. These phase regions has been confirmed by thermal quenching various compositions from the isotropic melt to different phase regions. Guided by the established phase diagram of HPTP/RM257 mixtures, photo-polymerization of the mixture has been carried out in different phase regions. The as-cured HPTP/p-(RM257) composites fabricated at isotropic phase (130 °C) remains single isotropic phase under optical microscope, whereas the SEM and TEM results show the bead-like microstructure with sub-micrometer scale. Polymerization-induced mesophase transition experiments have been carried out at isotropic temperatures slightly above the clearing point of the mixtures. Of particular interest is the development of liquid crystalline spherulites. Moreover, the fixation of the morphology is observed when the photopolymerization is carried out in the N, N + I, and N + Colh region. A generalized thermodynamic model for describing smectic A and smectic B ordering has been developed based on

  18. Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals

    SciTech Connect

    Govindaiah, T. N. Sreepad, H. R.; Sridhar, K. N.; Sridhara, G. R.; Nagaraja, N.

    2015-06-24

    A binary mixture of abietic acid and orthophosphoric acid (H{sub 3}PO{sub 4}) exhibits co-existence of biphasic region of Nematic+Isotropic (N+I), lyotropic Nematic (ND) and Smectic-G (SmG) phases. The mixture exhibits N+I, N and SmG phases at different concentrations and at different temperatures. Mixtures with all concentrations of abietic acid exhibit I→N+I→N→SmG phases sequentially when the specimen is cooled from its isotropic melt. These phases have been characterized by using differential scanning calorimetric, X-ray diffraction, and optical texture studies.

  19. Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals

    NASA Astrophysics Data System (ADS)

    Govindaiah, T. N.; Sreepad, H. R.; Sridhar, K. N.; Sridhara, G. R.; Nagaraja, N.

    2015-06-01

    A binary mixture of abietic acid and orthophosphoric acid (H3PO4) exhibits co-existence of biphasic region of Nematic+Isotropic (N+I), lyotropic Nematic (ND) and Smectic-G (SmG) phases. The mixture exhibits N+I, N and SmG phases at different concentrations and at different temperatures. Mixtures with all concentrations of abietic acid exhibit I→N+I→N→SmG phases sequentially when the specimen is cooled from its isotropic melt. These phases have been characterized by using differential scanning calorimetric, X-ray diffraction, and optical texture studies.

  20. Adsorption of hydrophobin/β-casein mixtures at the solid-liquid interface.

    PubMed

    Tucker, I M; Petkov, J T; Penfold, J; Thomas, R K; Cox, A R; Hedges, N

    2016-09-15

    The adsorption behaviour of mixtures of the proteins β-casein and hydrophobin at the hydrophilic solid-liquid surface have been studied by neutron reflectivity. The results of measurements from sequential adsorption and co-adsorption from solution are contrasted. The adsorption properties of protein mixtures are important for a wide range of applications. Because of competing factors the adsorption behaviour of protein mixtures at interfaces is often difficult to predict. This is particularly true for mixtures containing hydrophobin as hydrophobin possesses some unusual surface properties. At β-casein concentrations ⩾0.1wt% β-casein largely displaces a pre-adsorbed layer of hydrophobin at the interface, similar to that observed in hydrophobin-surfactant mixtures. In the composition and concentration range studied here for the co-adsorption of β-casein-hydrophobin mixtures the adsorption is dominated by the β-casein adsorption. The results provide an important insight into how the competitive adsorption in protein mixtures of hydrophobin and β-casein can impact upon the modification of solid surface properties and the potential for a wide range of colloid stabilisation applications. PMID:27288573

  1. Adsorption of hydrophobin/β-casein mixtures at the solid-liquid interface.

    PubMed

    Tucker, I M; Petkov, J T; Penfold, J; Thomas, R K; Cox, A R; Hedges, N

    2016-09-15

    The adsorption behaviour of mixtures of the proteins β-casein and hydrophobin at the hydrophilic solid-liquid surface have been studied by neutron reflectivity. The results of measurements from sequential adsorption and co-adsorption from solution are contrasted. The adsorption properties of protein mixtures are important for a wide range of applications. Because of competing factors the adsorption behaviour of protein mixtures at interfaces is often difficult to predict. This is particularly true for mixtures containing hydrophobin as hydrophobin possesses some unusual surface properties. At β-casein concentrations ⩾0.1wt% β-casein largely displaces a pre-adsorbed layer of hydrophobin at the interface, similar to that observed in hydrophobin-surfactant mixtures. In the composition and concentration range studied here for the co-adsorption of β-casein-hydrophobin mixtures the adsorption is dominated by the β-casein adsorption. The results provide an important insight into how the competitive adsorption in protein mixtures of hydrophobin and β-casein can impact upon the modification of solid surface properties and the potential for a wide range of colloid stabilisation applications.

  2. Water-in-ionic liquid microemulsion formation in solvent mixture of aprotic and protic imidazolium-based ionic liquids.

    PubMed

    Kusano, Takumi; Fujii, Kenta; Hashimoto, Kei; Shibayama, Mitsuhiro

    2014-10-14

    We report that water-in-ionic liquid microemulsions (MEs) are stably formed in an organic solvent-free system, i.e., a mixture of aprotic (aIL) and protic (pIL) imidazolium-based ionic liquids (ILs) containing the anionic surfactant dioctyl sulfosuccinate sodium salt (AOT). Structural investigations using dynamic light, small-angle X-ray, and small-angle neutron scatterings were performed for MEs formed in mixtures of aprotic 1-octyl-3-methylimidazolium ([C8mIm(+)]) and protic 1-alkylimidazolium ([CnImH(+)], n = 4 or 8) IL with a common anion, bis(trifluoromethanesulfonyl)amide ([TFSA(-)]). It was found that the ME structure strongly depends on the mixing composition of the aIL/pIL in the medium. The ME size appreciably increases with increasing pIL content in both [C8mIm(+)][TFSA(-)]/[C8ImH(+)][TFSA(-)] and [C8mIm(+)][TFSA(-)]/[C4ImH(+)][TFSA(-)] mixtures. The size is larger for the n = 8 system than that for the n = 4 system. These results indicate that the shell part of MEs is composed of both AOT and pIL cation, and the ME size can be tuned by pIL content in the aIL/pIL mixtures. PMID:25226398

  3. Induced smectic phases in phase diagrams of binary nematic liquid crystal mixtures.

    PubMed

    Huang, Tsang-Min; McCreary, Kathleen; Garg, Shila; Kyu, Thein

    2011-03-28

    To elucidate induced smectic A and smectic B phases in binary nematic liquid crystal mixtures, a generalized thermodynamic model has been developed in the framework of a combined Flory-Huggins free energy for isotropic mixing, Maier-Saupe free energy for orientational ordering, McMillan free energy for smectic ordering, Chandrasekhar-Clark free energy for hexagonal ordering, and phase field free energy for crystal solidification. Although nematic constituents have no smectic phase, the complexation between these constituent liquid crystal molecules in their mixture resulted in a more stable ordered phase such as smectic A or B phases. Various phase transitions of crystal-smectic, smectic-nematic, and nematic-isotropic phases have been determined by minimizing the above combined free energies with respect to each order parameter of these mesophases. By changing the strengths of anisotropic interaction and hexagonal interaction parameters, the present model captures the induced smectic A or smectic B phases of the binary nematic mixtures. Of particular importance is the fact that the calculated phase diagrams show remarkable agreement with the experimental phase diagrams of binary nematic liquid crystal mixtures involving induced smectic A or induced smectic B phase.

  4. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  5. Cellulose Solubility in Ionic Liquid Mixtures: Temperature, Cosolvent, and Antisolvent Effects.

    PubMed

    Minnick, David L; Flores, Raul A; DeStefano, Matthew R; Scurto, Aaron M

    2016-08-18

    Select ionic liquids (ILs) dissolve significant quantities of cellulose through disruption and solvation of inter- and intramolecular hydrogen bonds. In this study, thermodynamic solid-liquid equilibrium was measured with microcrystalline cellulose in a model IL, 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIm][DEP]) and mixtures with protic antisolvents and aprotic cosolvents between 40 and 120 °C. The solubility of cellulose in pure [EMIm][DEP] exhibits an asymptotic maximum of approximately 20 mass % above 100 °C. Solubility studies conducted on antisolvent mixtures with [EMIm][DEP] and [BMIm][Cl] indicate that protic solvents, ethanol, methanol, and water, significantly reduce the cellulose capacity of IL mixtures by 38-100% even at small antisolvent loadings (<5 mass %). Alternatively, IL-aprotic cosolvent (dimethyl sulfoxide, dimethylformamide, and 1,3-dimethyl-2-imidazolidinone) mixtures at mass ratios up to 1:1 enhance cellulose dissolution by 20-60% compared to pure [EMIm][DEP] at select temperatures. Interactions between the IL and molecular solvents were investigated by Kamlet-Taft solvatochromic analysis, FTIR, and NMR spectroscopy. The results indicate that preferential solvation of the IL cation and anion by co- and antisolvents impact the ability of IL ions to interact with cellulose thus affecting the cellulose dissolution capacity of IL-solvent mixtures. PMID:27447741

  6. Cellulose Solubility in Ionic Liquid Mixtures: Temperature, Cosolvent, and Antisolvent Effects.

    PubMed

    Minnick, David L; Flores, Raul A; DeStefano, Matthew R; Scurto, Aaron M

    2016-08-18

    Select ionic liquids (ILs) dissolve significant quantities of cellulose through disruption and solvation of inter- and intramolecular hydrogen bonds. In this study, thermodynamic solid-liquid equilibrium was measured with microcrystalline cellulose in a model IL, 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIm][DEP]) and mixtures with protic antisolvents and aprotic cosolvents between 40 and 120 °C. The solubility of cellulose in pure [EMIm][DEP] exhibits an asymptotic maximum of approximately 20 mass % above 100 °C. Solubility studies conducted on antisolvent mixtures with [EMIm][DEP] and [BMIm][Cl] indicate that protic solvents, ethanol, methanol, and water, significantly reduce the cellulose capacity of IL mixtures by 38-100% even at small antisolvent loadings (<5 mass %). Alternatively, IL-aprotic cosolvent (dimethyl sulfoxide, dimethylformamide, and 1,3-dimethyl-2-imidazolidinone) mixtures at mass ratios up to 1:1 enhance cellulose dissolution by 20-60% compared to pure [EMIm][DEP] at select temperatures. Interactions between the IL and molecular solvents were investigated by Kamlet-Taft solvatochromic analysis, FTIR, and NMR spectroscopy. The results indicate that preferential solvation of the IL cation and anion by co- and antisolvents impact the ability of IL ions to interact with cellulose thus affecting the cellulose dissolution capacity of IL-solvent mixtures.

  7. Communication: Unusual structure and transport in ionic liquid-hexane mixtures

    DOE PAGES

    Liang, Min; Khatun, Sufia; Castner, Edward W.

    2015-03-28

    Ionic liquids having a sufficiently amphiphilic cation can dissolve large volume fractions of alkanes, leading to mixtures with intriguing properties on molecular length scales. The trihexyl(tetradecyl)phosphonium cation paired with the bis(trifluoromethylsulfonyl)amide anion provides an ionic liquid that can dissolve large mole fractions of hexane. We present experimental results on mixtures of n-C6D14 with this ionic liquid. High- energy X-ray scattering studies reveal a persistence of the characteristic features of ionic liquid structure even for 80% dilution with n-C6D14. NMR self-diffusion results reveal decidedly non-hydrodynamic behavior where the self-diffusion of the neutral, non-polar n-C6D14 is on average a factor of 21more » times faster than for the cation. Exploitation of the unique structural and transport properties of these mixtures may lead to new opportunities for designer solvents for enhanced chemical reactivity and interface science.« less

  8. Communication: Unusual structure and transport in ionic liquid-hexane mixtures

    SciTech Connect

    Liang, Min; Khatun, Sufia; Castner, Edward W.

    2015-03-28

    Ionic liquids having a sufficiently amphiphilic cation can dissolve large volume fractions of alkanes, leading to mixtures with intriguing properties on molecular length scales. The trihexyl(tetradecyl)phosphonium cation paired with the bis(trifluoromethylsulfonyl)amide anion provides an ionic liquid that can dissolve large mole fractions of hexane. We present experimental results on mixtures of n-C6D14 with this ionic liquid. High- energy X-ray scattering studies reveal a persistence of the characteristic features of ionic liquid structure even for 80% dilution with n-C6D14. NMR self-diffusion results reveal decidedly non-hydrodynamic behavior where the self-diffusion of the neutral, non-polar n-C6D14 is on average a factor of 21 times faster than for the cation. Exploitation of the unique structural and transport properties of these mixtures may lead to new opportunities for designer solvents for enhanced chemical reactivity and interface science.

  9. Communication: Unusual structure and transport in ionic liquid-hexane mixtures

    SciTech Connect

    Liang, Min; Khatun, Sufia; Castner, Edward W.

    2015-03-28

    Ionic liquids having a sufficiently amphiphilic cation can dissolve large volume fractions of alkanes, leading to mixtures with intriguing properties on molecular length scales. The trihexyl(tetradecyl)phosphonium cation paired with the bis(trifluoromethylsulfonyl)amide anion provides an ionic liquid that can dissolve large mole fractions of hexane. We present experimental results on mixtures of n-C{sub 6}D{sub 14} with this ionic liquid. High-energy X-ray scattering studies reveal a persistence of the characteristic features of ionic liquid structure even for 80% dilution with n-C{sub 6}D{sub 14}. Nuclear magnetic resonance self-diffusion results reveal decidedly non-hydrodynamic behavior where the self-diffusion of the neutral, non-polar n-C{sub 6}D{sub 14} is on average a factor of 21 times faster than for the cation. Exploitation of the unique structural and transport properties of these mixtures may lead to new opportunities for designer solvents for enhanced chemical reactivity and interface science.

  10. Phase transition and chemical decomposition of liquid carbon dioxide and nitrogen mixture under extreme conditions

    NASA Astrophysics Data System (ADS)

    Xiao-Xu, Jiang; Guan-Yu, Chen; Yu-Tong, Li; Xin-Lu, Cheng; Cui-Ming, Tang

    2016-02-01

    Thermodynamic and chemical properties of liquid carbon dioxide and nitrogen (CO2-N2) mixture under the conditions of extremely high densities and temperatures are studied by using quantum molecular dynamic (QMD) simulations based on density functional theory including dispersion corrections (DFT-D). We present equilibrium properties of liquid mixture for 112 separate density and temperature points, by selecting densities ranging from ρ = 1.80 g/cm3 to 3.40 g/cm3 and temperatures from T = 500 K to 8000 K. In the range of our study, the liquid CO2-N2 mixture undergoes a continuous transition from molecular to atomic fluid state and liquid polymerization inferred from pair correlation functions (PCFs) and the distribution of various molecular components. The insulator-metal transition is demonstrated by means of the electronic density of states (DOS). Project supported by the National Natural Science Foundation of China (Grant Nos. 11374217, 11135012, and 11375262) and the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. 11176020).

  11. Ionic liquids and eutectic mixtures as solvent and template in synthesis of zeolite analogues.

    PubMed

    Cooper, Emily R; Andrews, Christopher D; Wheatley, Paul S; Webb, Paul B; Wormald, Philip; Morris, Russell E

    2004-08-26

    The challenges associated with synthesizing porous materials mean that new classes of zeolites (zeotypes)-such as aluminosilicate zeolites and zeolite analogues-together with new methods of preparing known zeotypes, continue to be of great importance. Normally these materials are prepared hydrothermally with water as the solvent in a sealed autoclave under autogenous pressure. The reaction mixture usually includes an organic template or 'structure-directing agent' that guides the synthesis pathway towards particular structures. Here we report the preparation of aluminophosphate zeolite analogues by using ionic liquids and eutectic mixtures. An imidazolium-based ionic liquid acts as both solvent and template, leading to four zeotype frameworks under different experimental conditions. The structural characteristics of the materials can be traced back to the solvent chemistry used. Because of the vanishingly low vapour pressure of ionic liquids, synthesis takes place at ambient pressure, eliminating safety concerns associated with high hydrothermal pressures. The ionic liquid can also be recycled for further use. A choline chloride/urea eutectic mixture is also used in the preparation of a new zeotype framework. PMID:15329717

  12. A molecular dynamics simulation study of dynamic process and mesoscopic structure in liquid mixture systems

    NASA Astrophysics Data System (ADS)

    Yang, Peng

    The focus of this dissertation is the Molecular Dynamics (MD) simulation study of two different systems. In thefirst system, we study the dynamic process of graphene exfoliation, particularly graphene dispersion using ionic surfactants (Chapter 2). In the second system, we investigate the mesoscopic structure of binary solute/ionic liquid (IL) mixtures through the comparison between simulations and corresponding experiments (Chapter 3 and 4). In the graphene exfoliation study, we consider two separation mechanisms: changing the interlayer distance and sliding away the relative distance of two single-layer graphene sheets. By calculating the energy barrier as a function of separation (interlayer or sliding-away) distance and performing sodium dodecyl sulfate (SDS) structure analysis around graphene surface in SDS surfactant/water + bilayer graphene mixture systems, we find that the sliding-away mechanism is the dominant, feasible separation process. In this process, the SDS-graphene interaction gradually replaces the graphene-graphene Van der Waals (VdW) interaction, and decreases the energy barrier until almost zero at critical SDS concentration. In solute/IL study, we investigate nonpolar (CS2) and dipolar (CH 3CN) solute/IL mixture systems. MD simulation shows that at low concentrations, IL is nanosegregated into an ionic network and nonpolar domain. It is also found that CS2 molecules tend to be localized into the nonpolar domain, while CH3CN interacts with nonpolar domain as well as with the charged head groups in the ionic network because of its amphiphilicity. At high concentrations, CH3CN molecules eventually disrupt the nanostructural organization. This dissertation is organized in four chapters: (1) introduction to graphene, ionic liquids and the methodology of MD; (2) MD simulation of graphene exfoliation; (3) Nanostructural organization in acetonitrile/IL mixtures; (4) Nanostructural organization in carbon disulfide/IL mixtures; (5) Conclusions. Results

  13. Observations of homogeneous phase separation in liquid He3-He4 mixtures

    NASA Technical Reports Server (NTRS)

    Hoffer, J. K.; Campbell, L. J.; Bartlett, R. J.

    1980-01-01

    The so-called miscibility gap that exists below the critical point in liquid He-3 - H-4 mixtures makes it possible to study binary phase composition, and the ensuing dispersions, in a system possessing an additional order parameter in one of the components. The physical behavior of a superfluid dispersion produced by pressure quenching an He-3 - He-4 mixture into the miscibility gap is described. The description applies both to quenches of homogeneous and phase-separated initial states in various regions of the miscibility gap.

  14. Electro-optic and viscoelastic properties of a ferroelectric liquid crystalline binary mixture

    NASA Astrophysics Data System (ADS)

    Dardas, Dorota

    2016-04-01

    This study describes the properties of a binary liquid crystalline mixture composed of commercially available materials, Ce-3 (4-(n-hexyloxy phenyl)-1-(2-fuethyl butyl) biphenyl-4-carboxylate) and Ce-8 (4-(2-methylbutyl) phenyl-4-n-octylbiphenyl-4-carboxylate), in a weight ratio of 50:50. Both compounds show polymesomorphism and ferroelectric properties within a relatively wide temperature range. Taken separately, each compound has its advantages and disadvantages from the technical point of view. The influence of temperature on the electro-optical and viscoelastic properties of the produced binary mixture is investigated in this paper.

  15. Tuning 'de Vries-like' properties in binary mixtures of liquid crystals with different molecular lengths.

    PubMed

    Song, Qingxiang; Bogner, Andreas; Giesselmann, Frank; Lemieux, Robert P

    2013-09-25

    Smectic liquid crystals with 'de Vries-like' properties are characterized by a maximum layer contraction of ≤1% upon transition from the orthogonal SmA phase to the tilted SmC phase. We show that binary mixtures of 'de Vries-like' and conventional SmC mesogens with a molecular length ratio of 1.34 undergo a SmA-SmC phase transition with a maximum layer contraction ranging from 1.0 to 1.9% depending on the mixture composition.

  16. Maxwell-Stefan diffusivities in binary mixtures of ionic liquids with dimethyl sulfoxide (DMSO) and H2O.

    PubMed

    Liu, Xin; Vlugt, Thijs J H; Bardow, André

    2011-07-01

    Ionic liquids (ILs) are promising solvents for applications ranging from CO2 capture to the pretreatment of biomass. However, slow diffusion often restricts their applicability. A thorough understanding of diffusion in ILs is therefore highly desirable. Previous research largely focused on self-diffusion in ILs. For practical applications, mutual diffusion is by far more important than self-diffusion. For describing mutual diffusion in multicomponent systems, the Maxwell-Stefan (MS) approach is commonly used. Unfortunately, it is difficult to obtain MS diffusivities from experiments, but they can be directly extracted from molecular dynamics (MD) simulations. In this work, MS diffusivities were computed in binary systems containing 1-alkyl-3-methylimidazolium chloride (C(n)mimCl, n = 2, 4, 8), water, and/or dimethyl sulfoxide (DMSO) using MD. The dependence of self- and MS diffusivities on mixture composition was investigated. Our results show the following: (1) For solutions of ILs in water and DMSO, self-diffusivities decrease strongly with increasing IL concentration. For DMSO-IL, a single exponential decay is observed. (2) In both water-IL and DMSO-IL, MS diffusivities vary by a factor of 10 within the concentration range which is, however, still significantly smaller than the variation of the self-diffusion coefficients. (3) The MS diffusivities of the IL are almost independent of the alkyl chain length. (4) ILs stay in a form of isolated ions in C(n)mimCl-H2O mixtures; however, dissociation into ions is much less observed in C(n)mimCl-DMSO systems. This has a large effect on the concentration dependence of MS diffusivities. (5) Recently, we proposed a new model for predicting the MS diffusivity at infinite dilution, that is, Đ(ij)(x(k-->)1) (Ind. Eng. Chem. Res. 2011, 50, 4776-4782). This quantity describes the friction between components i and j when both are infinitely diluted in component k. In contrast to earlier empirical models, our model is based on

  17. Critical comparison of molecular mixing and interaction models for liquids, solutions and mixtures.

    PubMed

    Rosenholm, Jarl B

    2010-04-22

    Surface properties of condensed matter, in particular solids are frequently characterized with probe liquids. The liquids are assigned physico-chemical parameters, such as solubility parameters, surface/interfacial tensions and Hamaker constants. Each parameter has been subdivided into two-to-five van der Waals (London, Debye and Keesom) and Lewis contributions. A critical comparison reveals that each contribution varies considerably distorting the balance between them. Despite this scatter each set of parameters representing a particular molecular interaction shows similar trends. Experimental verification of these multi-parameter contributions in multi-components systems remain, however uncertain. Three models involving solubility parameters, surface/interfacial tensions and Hamaker constants were compared for internal and mutual conceptual consistency. It is shown that Fowkes definition of work of adhesion as interfacial tension contradicts Dupre's definition as work process of adhesion. The exchange energy density (EED) process differs from the work of adhesion process by a factor two for the interfacial average term and for three-component systems the models differ substantially. The processes which are represented by Hamaker constants are in accord with the EED process for two-component systems, but assumed equal to work process of adhesion for three-component systems. Although the process representation is common for all models, it is shown that they represent only a fraction of the total energy balance. PMID:20202617

  18. Phase separations in mixtures of a liquid crystal and a nanocolloidal particle.

    PubMed

    Matsuyama, Akihiko

    2009-11-28

    We present a mean field theory to describe phase separations in mixtures of a liquid crystal and a nanocolloidal particle. By taking into account a nematic, a smectic A ordering of the liquid crystal, and a crystalline ordering of the nanoparticle, we calculate the phase diagrams on the temperature-concentration plane. We predict various phase separations, such as a smectic A-crystal phase separation and a smectic A-isotropic-crystal triple point, etc., depending on the interactions between the liquid crystal and the colloidal surface. Inside binodal curves, we find new unstable and metastable regions, which are important in the phase ordering dynamics. We also find a crystalline ordering of the nanoparticles dispersed in a smectic A phase and a nematic phase. The cooperative phenomena between liquid-crystalline ordering and crystalline ordering induce a variety of phase diagrams.

  19. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids

    SciTech Connect

    Finotello Alexia; Bara Jason E.; Narayan Suguna; Campder Dean; Noble Richard D.

    2008-07-01

    This study focuses on the solubility behaviors of CO{sub 2}, CH{sub 4}, and N{sub 2} gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ((C{sub 2}mim)(Tf{sub 2}N)) and l-ethyl-3-methylimidazolium tetrafluoroborate ((C{sub 2}mim)(BF{sub 4})) at 40{sup o}C and low pressures (about 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % (C{sub 2}mim)(BF{sub 4}) in (C{sub 2}-mim)(Tf2{sub N}). Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO{sub 2} with N{sub 2} or CH{sub 4} in pure (C{sub 2}mim)(BF4) can be enhanced by adding 5 mol% (C{sub 2}-mim)(Tf{sub 2}N).

  20. Simulating the vibrational spectra of ionic liquid systems: 1-Ethyl-3-methylimidazolium acetate and its mixtures

    NASA Astrophysics Data System (ADS)

    Thomas, Martin; Brehm, Martin; Hollóczki, Oldamur; Kelemen, Zsolt; Nyulászi, László; Pasinszki, Tibor; Kirchner, Barbara

    2014-07-01

    The vibrational spectra of the ionic liquid 1-ethyl-3-methylimidazolium acetate and its mixtures with water and carbon dioxide are calculated using ab initio molecular dynamics simulations, and the results are compared to experimental data. The new implementation of a normal coordinate analysis in the trajectory analyzer TRAVIS is used to assign the experimentally observed bands to specific molecular vibrations. The applied computational approaches prove to be particularly suitable for the modeling of bulk phase effects on vibrational spectra, which are highly important for the discussion of the microscopic structure in systems with a strong dynamic network of intermolecular interactions, such as ionic liquids.

  1. Simulating the vibrational spectra of ionic liquid systems: 1-ethyl-3-methylimidazolium acetate and its mixtures.

    PubMed

    Thomas, Martin; Brehm, Martin; Hollóczki, Oldamur; Kelemen, Zsolt; Nyulászi, László; Pasinszki, Tibor; Kirchner, Barbara

    2014-07-14

    The vibrational spectra of the ionic liquid 1-ethyl-3-methylimidazolium acetate and its mixtures with water and carbon dioxide are calculated using ab initio molecular dynamics simulations, and the results are compared to experimental data. The new implementation of a normal coordinate analysis in the trajectory analyzer TRAVIS is used to assign the experimentally observed bands to specific molecular vibrations. The applied computational approaches prove to be particularly suitable for the modeling of bulk phase effects on vibrational spectra, which are highly important for the discussion of the microscopic structure in systems with a strong dynamic network of intermolecular interactions, such as ionic liquids. PMID:25028030

  2. The suitability of concentration addition for predicting the effects of multi-component mixtures of up to 17 anti-androgens with varied structural features in an in vitro AR antagonist assay

    SciTech Connect

    Ermler, Sibylle; Scholze, Martin; Kortenkamp, Andreas

    2011-12-15

    The risks associated with human exposures to chemicals capable of antagonising the effects of endogenous androgens have attracted considerable recent interest. Exposure is typically to large numbers of chemicals with androgen receptor (AR) antagonist activity, yet there is limited evidence of the combined effects of multi-component mixtures of these chemicals. A few in vitro studies with mixtures of up to six AR antagonists suggest that the concept of concentration addition (CA) provides good approximations of experimentally observed mixture effects, but studies with larger numbers of anti-androgens, and with more varied structural features, are missing. Here we show that the mixture effects of up to 17 AR antagonists, comprising compounds as diverse as UV-filter substances, parabens, perfluorinated compounds, bisphenol-A, benzo({alpha})pyrene, synthetic musks, antioxidants and polybrominated biphenyls, can be predicted well on the basis of the anti-androgenicity of the single components using the concept of CA. We tested these mixtures in an in vitro AR-dependent luciferase reporter gene assay, based on MDA-kb2 cells. The effects of further mixtures, composed of four and six anti-androgens, could be predicted accurately by CA. However, there was a shortfall from expected additivity with a ten-component mixture at two different mixture ratios, but attempts to attribute these deviations to differential expression of hormone-metabolising CYP isoforms did not produce conclusive results. CA provides good approximations of in vitro mixture effects of anti-androgens with varying structural features. -- Highlights: Black-Right-Pointing-Pointer Humans are exposed to a large number of androgen receptor antagonists. Black-Right-Pointing-Pointer There is limited evidence of the combined effects of anti-androgenic chemicals. Black-Right-Pointing-Pointer We modelled the predictability of combined effects of up to 17 anti-androgens. Black-Right-Pointing-Pointer We tested the

  3. Tunable structures of mixtures of magnetic particles in liquid-crystalline matrices.

    PubMed

    Peroukidis, Stavros D; Lichtner, Ken; Klapp, Sabine H L

    2015-08-14

    We investigate the self-organization of a binary mixture of similar sized rods and dipolar soft spheres by means of Monte-Carlo simulations. We model interparticle interactions by employing anisotropic Gay-Berne, dipolar and soft-sphere interactions. In the limit of vanishing magnetic moments we obtain a variety of fully miscible liquid crystalline phases including nematic, smectic and lamellar phases. For the magnetic mixture, we find that the liquid crystalline matrix supports the formation of orientationally ordered ferromagnetic chains. Depending on the relative size of the species the chains align parallel or perpendicular to the director of the rods forming uniaxial or biaxial nematic, smectic and lamellar phases. As an exemplary external perturbation we apply a homogeneous magnetic field causing uniaxial or biaxial ordering to an otherwise isotropic state.

  4. Sedimentation of a two-dimensional colloidal mixture exhibiting liquid-liquid and gas-liquid phase separation: a dynamical density functional theory study.

    PubMed

    Malijevský, Alexandr; Archer, Andrew J

    2013-10-14

    We present dynamical density functional theory results for the time evolution of the density distribution of a sedimenting model two-dimensional binary mixture of colloids. The interplay between the bulk phase behaviour of the mixture, its interfacial properties at the confining walls, and the gravitational field gives rise to a rich variety of equilibrium and non-equilibrium morphologies. In the fluid state, the system exhibits both liquid-liquid and gas-liquid phase separation. As the system sediments, the phase separation significantly affects the dynamics and we explore situations where the final state is a coexistence of up to three different phases. Solving the dynamical equations in two-dimensions, we find that in certain situations the final density profiles of the two species have a symmetry that is different from that of the external potentials, which is perhaps surprising, given the statistical mechanics origin of the theory. The paper concludes with a discussion on this.

  5. Numerical Analysis of Multicomponent Suspension Droplets in High-Velocity Flame Spray Process

    NASA Astrophysics Data System (ADS)

    Gozali, Ebrahim; Mahrukh, Mahrukh; Gu, Sai; Kamnis, Spyros

    2014-08-01

    The liquid feedstock or suspension as a different mixture of liquid fuel ethanol and water is numerically studied in high-velocity suspension flame spray (HVSFS) process, and the results are compared for homogenous liquid feedstock of ethanol and water. The effects of mixture on droplet aerodynamic breakup, evaporation, combustion, and gas dynamics of HVSFS process are thoroughly investigated. The exact location where the particle heating is initiated (above the carrier liquid boiling point) can be controlled by increasing the water content in the mixture. In this way, the particle inflight time in the high-temperature gas regions can be adjusted avoiding adverse effects from surface chemical transformations. The mixture is modeled as a multicomponent droplet, and a convection/diffusion model, which takes into account the convective flow of evaporating material from droplet surface, is used to simulate the suspension evaporation. The model consists of several sub-models that include premixed combustion of propane-oxygen, non-premixed ethanol-oxygen combustion, modeling of multicomponent droplet breakup and evaporation, as well as heat and mass transfer between liquid droplets and gas phase.

  6. Volumetric properties of binary mixtures of benzene with cyano-based ionic liquids

    NASA Astrophysics Data System (ADS)

    Gonfa, Girma; Bustam, Mohamad Azmi; Moniruzzaman, Muhammad; Murugesan, Thanabalan

    2014-10-01

    The objective of this study is to investigate the volumetric properties of the binary mixtures comprised benzene and two ionic liquids, 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and 1-butyl-3-methyl- imidazolium dicyanamide ([ BMIM ][ N ( CN )2]( . Densities (ρ) and viscosities (μ) of the binary mixtures were measured over a temperature range of 293.15 to 323.15 K and at atmospheric pressure. Excess molar volumes and viscosity deviations were calculated from the experimental densities and viscosities values. The volumetric properties of the mixtures were changed significantly with the change of compositions and temperatures. It was also found that the value of excess molar volume and viscosity deviations were negative (-ve) over the entire range of compositions. The results have been interpreted in terms of molecular interactions of ILs and benzene.

  7. Vapor-liquid equilibria for the binary difluoromethane (R-32) + propane (R-290) mixture

    SciTech Connect

    Higashi, Y. . Dept. of Mechanical Engineering)

    1999-03-01

    The vapor-liquid equilibrium of the mixture composed of difluoromethane (R-32) and propane (R-290) was studied in the temperature range between 273.15 and 313.15 K. The experimental uncertainties of temperature, pressure, and composition measurements were estimated to be within [+-]10 mK, [+-]3 kPa, and [+-]0.4 mol%, respectively. Comparisons between the present data and available experimental data were made using the Helmholz free energy mixture model (HMM) adopted in the thermophysical properties program package, REFPOP 6.0, as a baseline. In addition, the existence of an azeotrope and the determination of new adjustable parameters for HMM for the R-32 + R-290 mixture are discussed.

  8. Vapor-liquid equilibria for the binary difluoromethane (R-32) + propane (R-290) mixture

    SciTech Connect

    Higashi, Y.

    1999-03-01

    The vapor-liquid equilibrium of the mixture composed of difluoromethane (R-32) and propane (R-290) was studied in the temperature range between 273.15 and 313.15 K. The experimental uncertainties of temperature, pressure, and composition measurements were estimated to be within {+-}10 mK, {+-}3 kPa, and {+-}0.4 mol%, respectively. Comparisons between the present data and available experimental data were made using the Helmholz free energy mixture model (HMM) adopted in the thermophysical properties program package, REFPOP 6.0, as a baseline. In addition, the existence of an azeotrope and the determination of new adjustable parameters for HMM for the R-32 + R-290 mixture are discussed.

  9. Divergent trend in density versus viscosity of ionic liquid/water mixtures: a molecular view from guanidinium ionic liquids.

    PubMed

    Singh, Akhil Pratap; Gardas, Ramesh L; Senapati, Sanjib

    2015-10-14

    Ionic liquids (ILs) have shown great potential in the dissolution and stability of biomolecules when a low-to-moderate quantity of water is added. Hence, determining the thermophysical properties and understanding these novel mixtures at the molecular level are of both fundamental and practical importance. In this context, here we report the synthesis of two nontoxic guanidinium cation based ILs, tetramethylguanidinium benzoate [TMG][BEN] and tetramethylguanidinium salicylate [TMG][SAL], and present a detailed comparison of their thermophysical properties in the presence of water. The results show that the [TMG][SAL]/water mixtures have higher density and higher apparent molar volume, but a lower viscosity and higher compressibility than the [TNG][BEN]/water mixtures. The measured viscosity and compressibility data are explained from ab initio quantum mechanical calculations and liquid-phase molecular dynamics simulations, where salicylate anions of denser [TMG][SAL]/water were found to exist as isolated ions due to intramolecular H-bonding. On the contrary, intermolecular H-bonding among the benzoate anions and their strong tendency to form an extended H-bonding network with water made [TMG][BEN]/water solutions more viscous and less compressible. This study shows the importance of probing these emerging solvents at the molecular-to-atomic level, which could be helpful in their optimal usage for task-specific applications.

  10. Superconducting cable cooling system by helium gas and a mixture of gas and liquid helium

    DOEpatents

    Dean, John W.

    1977-01-01

    Thermally contacting, oppositely streaming cryogenic fluid streams in the same enclosure in a closed cycle that changes from a cool high pressure helium gas to a cooler reduced pressure helium fluid comprised of a mixture of gas and boiling liquid so as to be near the same temperature but at different pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T.sub.1. By first circulating the fluid in a go leg from a refrigerator at one end of the line as a high pressure helium gas near the normal boiling temperature of helium; then circulating the gas through an expander at the other end of the line where the gas becomes a mixture of reduced pressure gas and boiling liquid at its boiling temperature; then by circulating the mixture in a return leg that is separated from but in thermal contact with the gas in the go leg and in the same enclosure therewith; and finally returning the resulting low pressure gas to the refrigerator for compression into a high pressure gas at T.sub.2 is a closed cycle, where T.sub.1 >T.sub.2, the temperature distribution is such that the line temperature is nearly constant along its length from the refrigerator to the expander due to the boiling of the liquid in the mixture. A heat exchanger between the go and return lines removes the gas from the liquid in the return leg while cooling the go leg.

  11. Shear viscosity of polar liquid mixtures via non-equilibrium molecular dynamics: water, methanol, and acetone

    NASA Astrophysics Data System (ADS)

    Wheeler Richard, Dean R.; Rowley, L.

    Non-equilibrium molecular dynamics (NEMD) with isobaric and isokinetic controls were used to simulate the shear viscosity for binary mixtures of water, methanol and acetone, and for ternary mixtures. In all, 22 different liquid composition points were simulated at 298.15 K and 0.1 MPa. A new set of acetone potential parameters was developed, while slight variants to existing water and methanol models were used. Long range Coulombic interactions were computed with the Ewald sum adapted to Lees-Edwards boundary conditions as formulated in Wheeler, D. R., Fuller, N. G., and Rowley, R. L., 1997, Molec. Phys., 92, 55. The attractive (dispersive) part of the Lennard-Jones (LJ) interactions also was handled by a lattice sum. A hybrid mixing rule was used for the LJ cross interactions. Viscosities extrapolated to zero shear compared well with experimental results, having a mean absolute error of 14% and no errors greater than 30%. Although the simulations successfully predicted viscosity maxima for mixtures high in water content, the peak heights tended to be too low, probably due to the limitations of the water model. The results suggest that NEMD may be a viable means of estimating viscosities for polar liquid mixtures with an unrestricted number of components.

  12. Association structures of ionic liquid/DMSO mixtures studied by high-pressure infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Jyh-Chiang; Lin, Kuan-Hung; Li, Sz-Chi; Shih, Pao-Ming; Hung, Kai-Chan; Lin, Sheng Hsien; Chang, Hai-Chou

    2011-01-01

    Using high-pressure infrared methods, we have investigated close interactions of charge-enhanced C-H-O type in ionic liquid/dimethyl sulfoxide (DMSO) mixtures. The solvation and association of the 1-butyl-3-methylimidazolium tetrafluoroborate (BMI^ + BF_4^ - ) and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BMM^ + BF_4^ - ) in DMSO-d6 were examined by analysis of C-H spectral features. Based on our concentration-dependent results, the imidazolium C-H groups are more sensitive sites for C-H-O than the alkyl C-H groups and the dominant imidazolium C-H species in dilute ionic liquid/DMSO-d6 should be assigned to the isolated (or dissociated) structures. As the dilute mixtures were compressed by high pressures, the loss in intensity of the bands attributed to the isolated structures was observed. In other words, high pressure can be used to perturb the association-dissociation equilibrium in the polar region. This result is remarkably different from what is revealed for the imidazolium C-H in the BMM^ + BF_4^ - /D2O mixtures. DFT-calculations are in agreement with our experimental results indicating that C4-H-O and C5-H-O interactions seem to play non-negligible roles for BMM^ + BF_4^ - /DMSO mixtures.

  13. True molecular solutions of natural cellulose in the binary ionic liquid-containing solvent mixtures.

    PubMed

    Rein, Dmitry M; Khalfin, Rafail; Szekely, Noemi; Cohen, Yachin

    2014-11-01

    Evidence is presented for the first time of true molecular dissolution of cellulose in binary mixtures of common polar organic solvents with ionic liquid. Cryogenic transmission electron microscopy, small-angle neutron-, X-ray- and static light scattering were used to investigate the structure of cellulose solutions in mixture of dimethyl formamide and 1-ethyl-3-methylimidazolium acetate. Structural information on the dissolved chains (average molecular weight ∼ 5 × 10(4)g/mol; gyration radius ∼ 36 nm, persistence length ∼ 4.5 nm), indicate the absence of significant aggregation of the dissolved chains and the calculated value of the second virial coefficient ∼ 2.45 × 10(-2)mol ml/g(2) indicates that this solvent system is a good solvent for cellulose. More facile dissolution of cellulose could be achieved in solvent mixtures that exhibit the highest electrical conductivity. Highly concentrated cellulose solution in pure ionic liquid (27 wt.%) prepared according to novel method, utilizing the rapid evaporation of a volatile co-solvent in binary solvent mixtures at superheated conditions, shows insignificant cellulose molecular aggregation. PMID:25129726

  14. True molecular solutions of natural cellulose in the binary ionic liquid-containing solvent mixtures.

    PubMed

    Rein, Dmitry M; Khalfin, Rafail; Szekely, Noemi; Cohen, Yachin

    2014-11-01

    Evidence is presented for the first time of true molecular dissolution of cellulose in binary mixtures of common polar organic solvents with ionic liquid. Cryogenic transmission electron microscopy, small-angle neutron-, X-ray- and static light scattering were used to investigate the structure of cellulose solutions in mixture of dimethyl formamide and 1-ethyl-3-methylimidazolium acetate. Structural information on the dissolved chains (average molecular weight ∼ 5 × 10(4)g/mol; gyration radius ∼ 36 nm, persistence length ∼ 4.5 nm), indicate the absence of significant aggregation of the dissolved chains and the calculated value of the second virial coefficient ∼ 2.45 × 10(-2)mol ml/g(2) indicates that this solvent system is a good solvent for cellulose. More facile dissolution of cellulose could be achieved in solvent mixtures that exhibit the highest electrical conductivity. Highly concentrated cellulose solution in pure ionic liquid (27 wt.%) prepared according to novel method, utilizing the rapid evaporation of a volatile co-solvent in binary solvent mixtures at superheated conditions, shows insignificant cellulose molecular aggregation.

  15. Effect of the oxygen balance on ignition and detonation properties of liquid explosive mixtures

    NASA Astrophysics Data System (ADS)

    Genetier, Marc; Osmont, Antoine; Baudin, Gerard

    2013-06-01

    The objective is to compare ignition and detonation properties of various liquid high explosives having negative up to positive oxygen balance (OB): nitromethane (OB < 0), saccharose and hydrogen peroxide based mixture (quasi nil OB), hydrogen peroxide with more than 90% purity (OB > 0). The decomposition kinetic rates and the equations of state (EOS) for the liquid mixtures and detonation products (DP) are the input data for a detonation model. EOS are theoretically determined using the Woolfolk et al universal liquid polar shock law and thermochemical computations for DP. The decomposition kinetic rate laws are determined to reproduce the shock to detonation transition for the mixtures submitted to planar plate impacts. Such a model is not sufficient to compute open field explosions. The aerial overpressure is well reproduced in the first microseconds, however, after it becomes worse at large expansion of the fireball and the impulse is underestimated. The problem of the DP EOS alone is that it takes into account only the detonation, the secondary combustion DP - air being not considered. To solve this problem a secondary combustion model has been developed to take into account the OB effect. The detonation model has been validated on planar plate impact experiments. The secondary combustion parameters were deduced from thermochemical computations. The whole model has been used to predict the effects of the oxygen balance on open air blast effects of spherical charges.

  16. Effect of the oxygen balance on ignition and detonation properties of liquid explosive mixtures

    NASA Astrophysics Data System (ADS)

    Genetier, M.; Osmont, A.; Baudin, G.

    2014-05-01

    The objective is to compare the ignition and detonation properties of various liquid high explosives having negative up to positive oxygen balance (OB): nitromethane (OB < 0), saccharose and hydrogen peroxide based mixture (quasi nil OB), hydrogen peroxide with more than 90% purity (OB > 0). The decomposition kinetic rates and the equations of state (EOS) for the liquid mixtures and detonation products (DP) are the input data for a detonation model. EOS are theoretically determined using the Woolfolk et al. universal liquid polar shock law and thermochemical computations for DP. The decomposition kinetic rate laws are determined to reproduce the shock to detonation transition for the mixtures submitted to planar plate impacts. Such a model is not sufficient to compute open field explosions. The aerial overpressure is well reproduced in the first few microseconds, however, after it becomes worse at large expansion of the fireball and the impulse is underestimated. The problem of the DP EOS alone is that it takes only the detonation into account, the secondary combustion DP - air is not considered. To solve this problem a secondary combustion model has been developed to take the OB effect into account. The detonation model has been validated on planar plate impact experiments. The secondary combustion parameters were deduced from thermochemical computations. The whole model has been used to predict the effects of the oxygen balance on open air blast effects of spherical charges.

  17. Mutual diffusion of binary liquid mixtures containing methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride.

    PubMed

    Guevara-Carrion, Gabriela; Janzen, Tatjana; Muñoz-Muñoz, Y Mauricio; Vrabec, Jadran

    2016-03-28

    Mutual diffusion coefficients of all 20 binary liquid mixtures that can be formed out of methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride without a miscibility gap are studied at ambient conditions of temperature and pressure in the entire composition range. The considered mixtures show a varying mixing behavior from almost ideal to strongly non-ideal. Predictive molecular dynamics simulations employing the Green-Kubo formalism are carried out. Radial distribution functions are analyzed to gain an understanding of the liquid structure influencing the diffusion processes. It is shown that cluster formation in mixtures containing one alcoholic component has a significant impact on the diffusion process. The estimation of the thermodynamic factor from experimental vapor-liquid equilibrium data is investigated, considering three excess Gibbs energy models, i.e., Wilson, NRTL, and UNIQUAC. It is found that the Wilson model yields the thermodynamic factor that best suits the simulation results for the prediction of the Fick diffusion coefficient. Four semi-empirical methods for the prediction of the self-diffusion coefficients and nine predictive equations for the Fick diffusion coefficient are assessed and it is found that methods based on local composition models are more reliable. Finally, the shear viscosity and thermal conductivity are predicted and in most cases favorably compared with experimental literature values. PMID:27036455

  18. Mutual diffusion of binary liquid mixtures containing methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride

    NASA Astrophysics Data System (ADS)

    Guevara-Carrion, Gabriela; Janzen, Tatjana; Muñoz-Muñoz, Y. Mauricio; Vrabec, Jadran

    2016-03-01

    Mutual diffusion coefficients of all 20 binary liquid mixtures that can be formed out of methanol, ethanol, acetone, benzene, cyclohexane, toluene, and carbon tetrachloride without a miscibility gap are studied at ambient conditions of temperature and pressure in the entire composition range. The considered mixtures show a varying mixing behavior from almost ideal to strongly non-ideal. Predictive molecular dynamics simulations employing the Green-Kubo formalism are carried out. Radial distribution functions are analyzed to gain an understanding of the liquid structure influencing the diffusion processes. It is shown that cluster formation in mixtures containing one alcoholic component has a significant impact on the diffusion process. The estimation of the thermodynamic factor from experimental vapor-liquid equilibrium data is investigated, considering three excess Gibbs energy models, i.e., Wilson, NRTL, and UNIQUAC. It is found that the Wilson model yields the thermodynamic factor that best suits the simulation results for the prediction of the Fick diffusion coefficient. Four semi-empirical methods for the prediction of the self-diffusion coefficients and nine predictive equations for the Fick diffusion coefficient are assessed and it is found that methods based on local composition models are more reliable. Finally, the shear viscosity and thermal conductivity are predicted and in most cases favorably compared with experimental literature values.

  19. Phase behaviour, interactions, and structural studies of (amines+ionic liquids) binary mixtures.

    PubMed

    Jacquemin, Johan; Bendová, Magdalena; Sedláková, Zuzana; Blesic, Marijana; Holbrey, John D; Mullan, Claire L; Youngs, Tristan G A; Pison, Laure; Wagner, Zdeněk; Aim, Karel; Costa Gomes, Margarida F; Hardacre, Christopher

    2012-05-14

    We present a study on the phase equilibrium behaviour of binary mixtures containing two 1-alkyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide-based ionic liquids, [C(n)mim] [NTf(2)] (n=2 and 4), mixed with diethylamine or triethylamine as a function of temperature and composition using different experimental techniques. Based on this work, two systems showing an LCST and one system with a possible hourglass shape are measured. Their phase behaviours are then correlated and predicted by using Flory-Huggins equations and the UNIQUAC method implemented in Aspen. The potential of the COSMO-RS methodology to predict the phase equilibria was also tested for the binary systems studied. However, this methodology is unable to predict the trends obtained experimentally, limiting its use for systems involving amines in ionic liquids. The liquid-state structure of the binary mixture ([C(2)mim] [NTf(2)]+diethylamine) is also investigated by molecular dynamics simulation and neutron diffraction. Finally, the absorption of gaseous ethane by the ([C(2)mim][NTf(2)]+diethylamine) binary mixture is determined and compared with that observed in the pure solvents.

  20. Experimental Investigation Evaporation of Liquid Mixture Droplets during Depressurization into Air Stream

    NASA Astrophysics Data System (ADS)

    Liu, L.; Bi, Q. C.; Terekhov, Victor I.; Shishkin, Nikolay E.

    2010-03-01

    The objective of this study is to develop experimental method to study the evaporation process of liquid mixture droplets during depressurization and into air stream. During the experiment, a droplet was suspended on a thermocouple; an infrared thermal imager was used to measure the droplet surface temperature transition. Saltwater droplets were used to investigate the evaporation process during depressurization, and volatile liquid mixtures of ethanol, methanol and acetone in water were applied to experimentally research the evaporation into air stream. According to the results, the composition and concentration has a complex influence on the evaporation rate and the temperature transition. With an increase in the share of more volatile component, the evaporation rate increases. While, a higher salt concentration in water results in a lower evaporation rate. The shape variation of saltwater droplet also depends on the mass concentration in solution, whether it is higher or lower than the eutectic point (22.4%). The results provide important insight into the complex heat and mass transfer of liquid mixture during evaporation.

  1. Dynamics of Multicomponent Polymers

    NASA Astrophysics Data System (ADS)

    Lodge, Timothy

    2004-03-01

    Multicomponent polymer systems - including blends, block, graft, and random copolymers, and their mixtures - are ubiquitous in polymer science and technology. A full understanding of the dynamics in such systems requires solution of at least three general problems: (i) what are the mechanisms of chain motion? (ii) how does the presence of spatial variations in composition affect chain translation and relaxation? (iii) how are the local dynamics of a given component in a mixture affected by composition? The reptation model, augmented by processes such as contour length fluctuations and constraint release, provides a very promising approach to (i). Measurements of translation diffusion in ordered block copolymers reveal the main features of (ii). Recent efforts towards the third problem have also begun to bear fruit. This talk will attempt to summarize the current state of affairs in this general area, and identify promising future directions.

  2. Theoretical performance of liquid ammonia, hydrazine and mixture of liquid ammonia and hydrazine as fuels with liquid oxygen biflouride as oxidant for rocket engines : I-mixture of liquid ammonia and hydrazine

    NASA Technical Reports Server (NTRS)

    Huff, Vearl N; Gordon, Sanford

    1952-01-01

    Theoretical performance for mixture of 36.3 percent liquid ammonia and 63.7 percent hydrazine with liquid oxygen bifluoride as rocket propellant was calculated on assumption of equilibrium composition during expansion for a wide range of fuel-oxidant and expansios ratios. Parameters included were specific impulse, combustion-chamber temperature, nozzle exit temperature, composition mean molecular weight, characteristic velocity, coefficient of thrust and ratio of nozzle-exit area to throat area. For chamber pressure of 300 pounds per square inch absolute and expansion to 1 atmosphere, maximum specific impulse was 295.8 pound-seconds per pound. Five percent by weight of water in the hydrazine lowered specific impulse from about one to three units over a wide range of weight-percent fuel.

  3. TMVOC-MP: a parallel numerical simulator for Three-PhaseNon-isothermal Flows of Multicomponent Hydrocarbon Mixtures inporous/fractured media

    SciTech Connect

    Zhang, Keni; Yamamoto, Hajime; Pruess, Karsten

    2008-02-15

    TMVOC-MP is a massively parallel version of the TMVOC code (Pruess and Battistelli, 2002), a numerical simulator for three-phase non-isothermal flow of water, gas, and a multicomponent mixture of volatile organic chemicals (VOCs) in multidimensional heterogeneous porous/fractured media. TMVOC-MP was developed by introducing massively parallel computing techniques into TMVOC. It retains the physical process model of TMVOC, designed for applications to contamination problems that involve hydrocarbon fuels or organic solvents in saturated and unsaturated zones. TMVOC-MP can model contaminant behavior under 'natural' environmental conditions, as well as for engineered systems, such as soil vapor extraction, groundwater pumping, or steam-assisted source remediation. With its sophisticated parallel computing techniques, TMVOC-MP can handle much larger problems than TMVOC, and can be much more computationally efficient. TMVOC-MP models multiphase fluid systems containing variable proportions of water, non-condensible gases (NCGs), and water-soluble volatile organic chemicals (VOCs). The user can specify the number and nature of NCGs and VOCs. There are no intrinsic limitations to the number of NCGs or VOCs, although the arrays for fluid components are currently dimensioned as 20, accommodating water plus 19 components that may be either NCGs or VOCs. Among them, NCG arrays are dimensioned as 10. The user may select NCGs from a data bank provided in the software. The currently available choices include O{sub 2}, N{sub 2}, CO{sub 2}, CH{sub 4}, ethane, ethylene, acetylene, and air (a pseudo-component treated with properties averaged from N{sub 2} and O{sub 2}). Thermophysical property data of VOCs can be selected from a chemical data bank, included with TMVOC-MP, that provides parameters for 26 commonly encountered chemicals. Users also can input their own data for other fluids. The fluid components may partition (volatilize and/or dissolve) among gas, aqueous, and NAPL

  4. Lignin dissolution in dialkylimidazolium-based ionic liquid-water mixtures.

    PubMed

    Wang, Yantao; Wei, Ligang; Li, Kunlan; Ma, Yingchong; Ma, Ningning; Ding, Shan; Wang, Linlin; Zhao, Deyang; Yan, Bing; Wan, Wenying; Zhang, Qian; Wang, Xin; Wang, Junmei; Li, Hui

    2014-10-01

    Lignin dissolution in dialkylimidazolium-based ionic liquid (IL)-water mixtures (40wt%-100wt% IL content) at 60°C was investigated. The IL content and type are found to considerably affect lignin solubility. For the IL-water mixtures except 1-butyl-3-methylimidazolium tetrafluoroborate ([C4C1im]BF4), the maximum lignin solubility can be achieved at 70wt% IL content. Lignin solubility in IL-water mixtures with different cations follows the order 1-butyl-3-methylimidazolium ([C4C1im](+))>1-hexyl-3-methylimidazolium ([C6C1im](+))>1-ethyl-3-methylimidazolium ([C2C1im](+))>1-octyl-3-methylimidazolium ([C8C1im](+))>1-butyl-3-ethylimidazolium ([C4C2im](+))>1-butyl-3-propylimidazolium ([C4C3im](+)). For IL mixtures with different anions, lignin solubility decreases in the following order: methanesulfonate (MeSO3(-))>acetate (MeCO2(-))>bromide (Br(-))>dibutylphosphate (DBP(-)). Evaluation using the theory of Hansen solubility parameter (HSP) is consistent with the experimental results, suggesting that HSP can aid in finding the appropriate range of IL content for IL-water mixtures. However, HSP cannot be used to evaluate the effect of IL type on lignin solubility. PMID:25164342

  5. Binary mixtures of liquid crystalline compounds with a reentrant smectic-A* phase.

    PubMed

    Podoliak, Natalia; Novotná, Vladimíra; Glogarová, Milada; Pociecha, Damian; Gorecka, Ewa; Kašpar, Miroslav; Hamplová, Věra

    2011-12-01

    Binary mixtures of chiral liquid crystalline homologs have been studied. One compound designated 9ZBL exhibited reentrancy of a paraelectric smectic-A* phase, SmA*(RE), below the ferroelectric SmC* phase in the SmA*-SmC*-SmA*RE phase sequence. Stabilization of the SmA(RE) phase is established from studying binary mixtures of 9ZBL with its neighboring homologs 8ZBL and 10ZBL. Compound 8ZBL exhibits only SmA* phase in a wide temperature range and for 10ZBL the SmA*-SmC* phase sequence is observed on cooling. X-ray studies, dielectric spectroscopy, polarization, and tilt angle measurements have been carried out to characterize studied materials. For binary mixtures 9ZBL-10ZBL the reentrant SmA_(RE*) phase is observed for all studied concentrations. For binary mixtures 9ZBL-8ZBL a very small amount of 8ZBL (up to 0.5 mole %) causes disappearance of the SmC* phase. Nevertheless, a small anomaly in the temperature dependencies of the layer spacing, d(T), accompanied by a significant decrease in diffracted x-ray intensity occurs within the SmA* phase for mixtures containing up to 20 mole % of 8ZBL. This anomaly is evidence of the existence of a boundary between the SmA* and SmA(RE*) phases, thus proving their different nature.

  6. Fingerprint analysis, multi-component quantitation, and antioxidant activity for the quality evaluation of Salvia miltiorrhiza var. alba by high-performance liquid chromatography and chemometrics.

    PubMed

    Zhang, Danlu; Duan, Xiaoju; Deng, Shuhong; Nie, Lei; Zang, Hengchang

    2015-10-01

    Salvia miltiorrhiza Bge. var. alba C.Y. Wu and H.W. Li has wide prospects in clinical practice. A useful comprehensive method was developed for the quality evaluation of S. miltiorrhiza var. alba by three quantitative parameters: high-performance liquid chromatography fingerprint, ten-component contents, and antioxidant activity. The established method was validated for linearity, precision, repeatability, stability, and recovery. Principal components analysis and hierarchical clustering analysis were both used to evaluate the quality of the samples from different origins. The results showed that there were category discrepancies in quality of S. miltiorrhiza var. alba samples according to the three quantitative parameters. Multivariate linear regression was adopted to explore the relationship between components and antioxidant activity. Three constituents, namely, danshensu, rosmarinic acid, and salvianolic acid B, significantly correlated with antioxidant activity, and were successfully elucidated by the optimized multivariate linear regression model. The combined use of high-performance liquid chromatography fingerprint analysis, simultaneous multicomponent quantitative analysis, and antioxidant activity for the quality evaluation of S. miltiorrhiza var. alba is a reliable, comprehensive, and promising approach, which might provide a valuable reference for other herbal products in general to improve their quality control.

  7. CHROMATOGRAPHIC ALTERATION OF A NONIONIC SURFACTANT MIXTURE DURING TRANSPORT IN DENSE NONAQUEOUS PHASE LIQUID CONTAMINATED SEDIMENT (R826650)

    EPA Science Inventory

    Chromatographic alteration of a nonionic surfactant mixture during transport through DNAPL-contaminated aquifer sediment may occur due to differential loss of oligomers to sediment and to dense nonaqueous phase liquid (DNAPL). These losses may significantly alter the solubilizing...

  8. Another glimpse over the salting-out assisted liquid-liquid extraction in acetonitrile/water mixtures.

    PubMed

    Valente, Inês Maria; Gonçalves, Luís Moreira; Rodrigues, José António

    2013-09-20

    The use of the salting-out effect in analytical chemistry is very diverse and can be applied to increase the volatility of the analytes in headspace extractions, to cause the precipitation of proteins in biological samples or to improve the recoveries in liquid-liquid extractions. In the latter, the salting-out process can be used to create a phase separation between water-miscible organic solvents and water. Salting-out assisted liquid-liquid extraction (SALLE) is an advantageous sample preparation technique aiming HPLC-UV analysis when developing analytical methodologies. In fact, some new extraction methodologies like QuEChERS include the SALLE concept. This manuscript discusses another point of view over SALLE with particular emphasis over acetonitrile-water mixtures for HPLC-UV analysis; the influence of the salting-out agents, their concentration and the water-acetonitrile volume ratios were the studied parameters. α-dicarbonyl compounds and beer were used as test analytes and test samples, respectively. The influence of the studied parameters was characterized by the obtained phase separation volume ratio and the fraction of α-dicarbonyls extracted to the acetonitrile phase. Results allowed the distribution of salts within three groups according to the phase separation and their extractability: (1) chlorides and acetates, (2) carbonates and sulfates and (3) magnesium sulfate; of all tested salts, sodium chloride had the highest influence on the α-dicarbonyls fraction extracted.

  9. Dielectric properties measurement method in the microwave frequencies range for non-polar/polar liquid mixtures characterization

    NASA Astrophysics Data System (ADS)

    Surducan, E.; Neamtu, C.; Ienciu, M.; Surducan, V.; Limare, A.; Fourel, L.

    2015-12-01

    We present a method based on dielectric properties measurements over a large spectrum of frequencies, in the microwave (MW) domain, in order to characterize a liquid mixture. The liquid mixtures consist of non-polar fluids (silicone oil, diesel fuel) and polar additives, in order to increase the specific MW absorption of the mixture for further MW power processing. We have measured the MW specific absorptions for mixtures of silicone oil with 20% and 30% (w/w) isopropanol. In both cases, the mixtures are sufficiently stable over time to allow further studies of thermal convection dynamics initiated by MW heating. For a mixture of diesel fuel with 10% (w/w) alkyl polyglycoside, the main observation was that its MW specific absorption varies over time after the mechanical mixing process.

  10. Viscosity of liquid mixtures: the Vesovic-Wakeham method for chain molecules.

    PubMed

    de Wijn, Astrid S; Riesco, Nicolas; Jackson, George; Trusler, J P Martin; Vesovic, Velisa

    2012-02-21

    New expressions for the viscosity of liquid mixtures, consisting of chain-like molecules, are derived by means of Enskog-type analysis. The molecules of the fluid are modelled as chains of equally sized, tangentially joined, and rigid spheres. It is assumed that the collision dynamics in such a fluid can be approximated by instantaneous collisions. We determine the molecular size parameters from the viscosity of each pure species and show how the different effective parameters can be evaluated by extending the Vesovic-Wakeham (VW) method. We propose and implement a number of thermodynamically consistent mixing rules, taking advantage of SAFT-type analysis, in order to develop the VW method for chain molecules. The predictions of the VW-chain model have been compared in the first instance with experimental viscosity data for octane-dodecane and methane-decane mixtures, thus, illustrating that the resulting VW-chain model is capable of accurately representing the viscosity of real liquid mixtures. PMID:22360255

  11. A Reflective Photonic Crystal Fiber Temperature Sensor Probe Based on Infiltration with Liquid Mixtures

    PubMed Central

    Wang, Ran; Yao, Jianquan; Miao, Yinping; Lu, Ying; Xu, Degang; Luan, Nannan; Musideke, Mayilamu; Duan, Liangcheng; Hao, Congjing

    2013-01-01

    In this paper, a reflective photonic crystal fiber (PCF) sensor probe for temperature measurement has been demonstrated both theoretically and experimentally. The performance of the device depends on the intensity modulation of the optical signal by liquid mixtures infiltrated into the air holes of commercial LMA-8 PCFs. The effective mode field area and the confinement loss of the probe are both proved highly temperature-dependent based on the finite element method (FEM). The experimental results show that the reflected power exhibits a linear response with a temperature sensitivity of about 1 dB/°C. The sensor probe presents a tunable temperature sensitive range due to the concentration of the mixture components. Further research illustrates that with appropriate mixtures of liquids, the probe could be developed as a cryogenic temperature sensor. The temperature sensitivity is about 0.75 dB/°C. Such a configuration is promising for a portable, low-power and all-in-fiber device for temperature or refractive index monitoring in chemical or biosensing applications. PMID:23787726

  12. Structural properties of geminal dicationic ionic liquid/water mixtures: a theoretical and experimental insight.

    PubMed

    Serva, Alessandra; Migliorati, Valentina; Lapi, Andrea; Aquilanti, Giuliana; Arcovito, Alessandro; D'Angelo, Paola

    2016-06-28

    The structural behavior of geminal dicationic ionic liquid 1,n-bis[3-methylimidazolium-1-yl] alkane bromide ([Cn(mim)2]Br2)/water mixtures has been studied using extended X-ray absorption fine structure (EXAFS) spectroscopy in combination with molecular dynamics (MD) simulations. The properties of the mixtures are investigated as a function of both water concentration and alkyl-bridge chain length. The very good agreement between the EXAFS experimental data and the theoretical curves calculated from the MD structural results has proven the validity of the theoretical framework used for all of the investigated systems. In all the solutions the water molecules are preferentially coordinated with the Br(-) ion, even if a complex network of interactions among dications, anions and water molecules takes place. The local molecular arrangement around the bromide ion is found to change with increasing water content, as more and more water molecules are accomodated in the Br(-) first coordination shell. Moreover, with the decrease of the alkyl-bridge chain length, the interactions between dications and anions increase, with Br(-) forming a bridge between the two imidazolium rings of the same dication. On the other hand, in [Cn(mim)2]Br2/water mixtures with long alkyl-bridge chains peculiar internal arrangements of the dications are found, leading to different structural features of geminal dicationic ionic liquids as compared to their monocationic counterparts.

  13. Viscosity of liquid mixtures: The Vesovic-Wakeham method for chain molecules

    NASA Astrophysics Data System (ADS)

    de Wijn, Astrid S.; Riesco, Nicolas; Jackson, George; Martin Trusler, J. P.; Vesovic, Velisa

    2012-02-01

    New expressions for the viscosity of liquid mixtures, consisting of chain-like molecules, are derived by means of Enskog-type analysis. The molecules of the fluid are modelled as chains of equally sized, tangentially joined, and rigid spheres. It is assumed that the collision dynamics in such a fluid can be approximated by instantaneous collisions. We determine the molecular size parameters from the viscosity of each pure species and show how the different effective parameters can be evaluated by extending the Vesovic-Wakeham (VW) method. We propose and implement a number of thermodynamically consistent mixing rules, taking advantage of SAFT-type analysis, in order to develop the VW method for chain molecules. The predictions of the VW-chain model have been compared in the first instance with experimental viscosity data for octane-dodecane and methane-decane mixtures, thus, illustrating that the resulting VW-chain model is capable of accurately representing the viscosity of real liquid mixtures.

  14. Phase behavior of chromonic liquid crystal mixtures of Sunset Yellow and Disodium Cromoglycate

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Akihiro; Smith, Gregory; Yi, Youngwoo; Xu, Charles; Biffi, Silvia; Serra, Francesca; Bellini, Tommaso; Clark, Noel

    2014-03-01

    Chromonic liquid crystals (CLCs) are formed when planar molecules dissolved in water stack into rod-like aggregates that can order as liquid crystals. Isotropic, nematic, and M-phases can be observed depending on the degree of molecular orientational and positional order by variation of the CLC concentration. We focused on mixtures of two well-known CLCs, Sunset Yellow, a food dye, and disodium cromoglycate (DSCG), an asthma medication. In order to study the phase behaviors of these mixtures, we observed their textures in glass cells and capillaries using polarized light microscopy. We report here a ternary phase diagram describing the complete phase behavior of the CLC mixtures. We observed a variety of phase behaviors depending on species ratio and concentration. In the isotropic phase, no clear phase separation of the two dyes was observed, while separation did occur in many nematic and M-phase combinations. We will also describe phase observations made using a light spectroscopy and bulk centrifugal partitioning. Grant support: NSF DMR 1207606 and NSF MRSEC DMR-0820579.

  15. Coarse-Grained Molecular Monte Carlo Simulations of Liquid Crystal-Nanoparticle Mixtures

    NASA Astrophysics Data System (ADS)

    Neufeld, Ryan; Kimaev, Grigoriy; Fu, Fred; Abukhdeir, Nasser M.

    Coarse-grained intermolecular potentials have proven capable of capturing essential details of interactions between complex molecules, while substantially reducing the number of degrees of freedom of the system under study. In the domain of liquid crystals, the Gay-Berne (GB) potential has been successfully used to model the behavior of rod-like and disk-like mesogens. However, only ellipsoid-like interaction potentials can be described with GB, making it a poor fit for many real-world mesogens. In this work, the results of Monte Carlo simulations of liquid crystal domains using the Zewdie-Corner (ZC) potential are presented. The ZC potential is constructed from an orthogonal series of basis functions, allowing for potentials of essentially arbitrary shapes to be modeled. We also present simulations of mixtures of liquid crystalline mesogens with nanoparticles. Experimentally these mixtures have been observed to exhibit microphase separation and formation of long-range networks under some conditions. This highlights the need for a coarse-grained approach which can capture salient details on the molecular scale while simulating sufficiently large domains to observe these phenomena. We compare the phase behavior of our simulations with that of a recently presented continuum theory. This work was made possible by the Natural Sciences and Engineering Research Council of Canada and Compute Ontario.

  16. Optical studies of a binary liquid crystal mixture exhibiting induced smectic A phase

    NASA Astrophysics Data System (ADS)

    Thingujam, Kiranmala; Bhattacharjee, Ayon; Choudhury, Basana; Sarkar, S. D.

    2016-08-01

    A binary liquid crystalline mixture of a monotropic polar compound 4-cyanophenyl 4'- n-pentyl benzoate (CPPB) and an enantiotropic non-polar compound 4- n-hexyl phenyl 4- n'-pentyloxy benzoate (ME5O.6) shows the presence of an induced smectic A phase in the region 0.1 ≤ x CPPB ≤ 0.82, where x CPPB is the mole fraction of CPPB. The results of texture study, density study and refractive index measurements of the eutectic mixture along with those of the pure samples are reported in this paper. The density values of the eutectic mixture are found to be much higher than that of the pure samples. The determination of order parameters of the pure samples and eutectic mixture has been carried out. In order to determine the order parameters of the samples, we have used different methods, Vuks', Neugebauer's, modified Vuks' and direct extrapolation method. The results of order parameters obtained from the different approaches are compared and analysed in detail.

  17. Two-step switching in dual-frequency nematic liquid crystal mixtures

    NASA Astrophysics Data System (ADS)

    Mrukiewicz, M.; Perkowski, P.; Piecek, W.; Mazur, R.; Chojnowska, O.; Garbat, K.

    2015-11-01

    The so-called dual-frequency nematic mixtures are very promising components for applications in fast operating devices. Compared with classical nematics, they exhibit positive or negative anisotropy of the electric permittivity depending on the applied frequencies of an external electric field. Owing to this property, an overall switching process from planar to homeotropic orientations, and vice versa, can be shortened by using the electric field with two different frequencies. Electro-optical switching characteristics of transmission versus time as a function of applied voltage were obtained for two different dual-frequency mixtures in twisted nematic cells. For one of the investigated mixtures, unusual decrease in the light transmission at switching from the homeotropic to planar orientation at threshold voltage was observed. The switching process apparently occurs in two steps. The mechanism of the two-step switching at twisted dual-frequency nematic structures was discussed. The explanation of the switching mechanism takes into account the influence of the electric field with different frequencies on molecules with transverse and longitudinal dipole moments. Moreover, molecular structure of compounds constituting the mixtures was analyzed. Additionally, response times of the switching driven with low and high frequency pulses were shown. This work helps to understand the molecular interaction and electro-optical switching in the dual-frequency nematic liquid crystals.

  18. Dynamical properties of alcohol + 1-hexyl-3-methylimidazolium ionic liquid mixtures: a computer simulation study.

    PubMed

    Méndez-Morales, Trinidad; Carrete, Jesús; García, Manuel; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M

    2011-12-29

    In this work, extensive molecular dynamics simulations of the dynamics of mixtures of ionic liquids (ILs) composed of the cation 1-hexyl-3-methylimidazolium and several anions of different hydrophobicity degrees (Cl(-), BF(4)(-), PF(6)(-)) with alcohols of different chain lengths (methanol and ethanol) are reported. We evaluated the influence of the nature of the anion, the length of the molecular chain of the alcohol, and the alcohol concentration on some dynamical properties of the mixtures, such as self-diffusion coefficients of all the species, mean square displacements (with an analysis of both ballistic and diffusive regimes), and velocity autocorrelation functions of alcohol molecules. The diffusivity of the mixtures was found to be highly dependent on the nature of the anion since the interaction between chloride and alcohols is greater than that with fluorinated anions and leads to slower dynamics. Additionally, our results show that self-diffusion coefficients increase with alcohol concentration. On the other hand, a subdiffusive regime over thousands of picoseconds was detected at intermediate times through analysis of the center-of-mass mean square displacements of alcohol molecules, a region that becomes narrower as alcohol concentration increases. Finally, the study of the role of the anion and of solvent concentration on velocity autocorrelation functions reflects an increase in mean collision times as the amount of alcohol increases until the value of pure alcohols is reached. These collision times are smaller in mixtures with halogenated ILs.

  19. Serpentine diffusion trajectories and the Ouzo effect in partially miscible ternary liquid mixtures.

    PubMed

    Krishna, Rajamani

    2015-11-01

    This work investigates the transient equilibration process when partially miscible ternary liquid mixtures of two different compositions are brought into contact with each other. Diffusional coupling effects are shown to become increasingly significant as the mixture compositions approach the meta-stable regions of the phase equilibrium diagrams. The proper modelling of coupled diffusion phenomena requires the use of a Fick diffusivity matrix [D], with inclusion of non-zero off-diagonal elements. The primary objective of this article is to develop a simple, robust, procedure for the estimation of the matrix [D], using the Maxwell-Stefan (M-S) formulation as a convenient starting point. In the developed simplified approach, the Fick diffusivity matrix [D] is expressed as the product of a scalar diffusivity and the matrix of thermodynamic correction factors [Γ]. By detailed examination of experimental data for the matrix [D] in a wide variety of ternary mixtures, it is deduced that the major contribution of diffusional coupling arises from the contributions of non-ideal solution thermodynamics, quantified by the matrix of thermodynamic correction factors [Γ]. An important consequence of strong thermodynamic coupling is that equilibration trajectories are serpentine in shape and may exhibit incursions into meta-stable zones opening up the possibility of spontaneous emulsification and the Ouzo effect. If diffusional coupling effects are ignored, the equilibration trajectory is linear in composition space. For a wide variety of partially miscible ternary mixtures, it is demonstrated that the corresponding linear equilibration trajectories do not anticipate the possibility of emulsification.

  20. Density functional theory of gas-liquid phase separation in dilute binary mixtures.

    PubMed

    Okamoto, Ryuichi; Onuki, Akira

    2016-06-22

    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas [Formula: see text] (the Gibbs energy of transfer) is considerably larger than the thermal energy [Formula: see text] for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by [Formula: see text], where [Formula: see text] is the solute density added in liquid. For [Formula: see text], phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  1. Measurements of the Liquid Viscosities of Mixtures of Isobutane with Squalane to 30 MPa

    NASA Astrophysics Data System (ADS)

    Kumagai, A.; Tomida, D.; Yokoyama, C.

    2007-08-01

    The viscosities of liquid mixtures of isobutane with squalane, which seem to be representative of mixtures of refrigerants with refrigeration oil, were measured from 273.15 to 333.15 K at pressures to 30 MPa using a falling-body viscometer. The uncertainty of the measurements was estimated to be no larger than 2.9%. The experimental viscosity values were fitted with a Tait-like equation within 2.8%. There are large deviations between the experimental data and calculated values predicted by the equation of Kanti et al., which is derived from Flory’s theory. By introducing two index numbers of the energetic mixing rule into the equation, the predictions could be improved considerably.

  2. The Influence of Chain Dynamics on the Far Infrared Spectrum of Liquid Methanol-Water Mixtures

    SciTech Connect

    Woods, K.N.; Wiedemann, H.; /SLAC, SSRL

    2005-07-12

    Far-infrared absorption spectroscopy has been used to study the low frequency ({center_dot} 100 cm{sup -1}) intermolecular modes of methanol in mixtures with water. With the aid of a first principles molecular dynamics simulation on an equivalent system, a detailed understanding about the origin of the low frequency IR modes has been established. The total dipole spectrum from the simulation suggests that the bands appearing in the experimental spectra at approximately 55 cm{sup -1} and 70 cm{sup -1} in methanol and methanol-rich mixtures arise from both fluctuations and torsional motions occurring within the methanol hydrogen-bonded chains. The influence of these modes on both the solvation dynamics and the relaxation mechanisms in the liquid are discussed within the context of recent experimental and theoretical results that have emerged from studies focusing on the short time dynamics in the methanol hydrogen bond network.

  3. Vapor-liquid equilibrium of near-critical binary alkane mixtures

    SciTech Connect

    Rainwater, J.C.; Williamson, F.R.; Hauley, H.J.M.; Cezairliyan, A.

    1986-01-01

    The modified Leung-Griffiths model of Rainwater and Moldover is used to correlate vapor-liquid equilibrium (VLE) surfaces in pressure, temperature, and density for binary mixtures in the near-critical region. The systems studied are butane-pentane, propane-isopentane, butane-hexane, and ethane-butane. The model, which has also successfully fit several other mixtures, is based on scalinglaw equations of state expressed in terms of field variables. It incorporates a variation of the principle of corresponding states as well as the coupling of density and composition change across the phase boundary. As the width of the dew-bubble curves increases, additional parameters are required to obtain successful VLE correlations.

  4. Vapor-liquid equilibrium of near-critical binary alkane mixtures

    NASA Astrophysics Data System (ADS)

    Rainwater, J. C.; Williamson, F. R.

    1986-01-01

    The modified Leung-Griffiths model of Rainwater and Moldover is used to correlate vapor-liquid equilibrium (VLE) surfaces in pressure, temperature, and density for binary mixtures in the near-critical region. The systems studied are butane-pentane, propane-isopentane, butane-hexane, and ethane-butane. The model, which has also successfully fit several other mixtures, is based on scaling-law equations of state expressed in terms of field variables. It incorporates a variation of the principle of corresponding states as well as the coupling of density and composition change across the phase boundary. As the width of the dew-bubble curves increases, additional parameters are required to obtain successful VLE correlations.

  5. Direct Conversion of Mono- and Polysaccharides into 5-Hydroxymethylfurfural Using Ionic-Liquid Mixtures.

    PubMed

    Siankevich, Sviatlana; Fei, Zhaofu; Scopelliti, Rosario; Jessop, Philip G; Zhang, Jiaguang; Yan, Ning; Dyson, Paul J

    2016-08-23

    Platform chemicals are usually derived from petrochemical feedstocks. A sustainable alternative commences with lignocellulosic biomass, a renewable feedstock, but one that is highly challenging to process. Ionic liquids (ILs) are able to solubilize biomass and, in the presence of catalysts, convert the biomass into useful platform chemicals. Herein, we demonstrate that mixtures of ILs are powerful systems for the selective catalytic transformation of cellulose into 5-hydroxymethylfurfural (HMF). Combining ILs with continuous HMF extraction into methyl-isobutyl ketone or 1,2-dimethoxyethane, which form a biphase with the IL mixture, allows the online separation of HMF in high yield. This one-step process is operated under relatively mild conditions and represents a significant step forward towards sustainable HMF production. PMID:27345462

  6. Rational approach to optimize cellulase mixtures for hydrolysis of regenerated cellulose containing residual ionic liquid.

    PubMed

    Engel, Philip; Krull, Susan; Seiferheld, Bianca; Spiess, Antje C

    2012-07-01

    For the efficient production of glucose for platform chemicals or biofuels, cellulosic biomass is pretreated and subsequently hydrolyzed with cellulases. Although ionic liquids (IL) are known to effectively pretreat cellulosic biomass, the hydrolysis of IL pretreated biomass has not been optimized so far. Here, we present a semi-empirical model to rationally optimize the hydrolysis of pretreated α-cellulose - regenerated from IL and containing residual IL from the pretreatment. First, the influence of the IL MMIM DMP on the individual cellulases endoglucanase I, cellobiohydrolase I and β-glucosidase was investigated. Second, an enzyme loading-dependent model was developed to describe kinetics for the individual cellulases and cellulase mixtures. Third, this model was used to optimize the cellulase mixture for the efficient hydrolysis of regenerated cellulose containing residual IL. Finally, we could significantly increase the initial hydrolysis rate in 10% (v/v) MMIM DMP by 49% and the sugar yield by 10% points. PMID:22100231

  7. Induced Mesophase in Mixtures of Photopolymerizable Hyperbranched Polyester and Liquid Crystal Mesogen

    NASA Astrophysics Data System (ADS)

    Kim, Namil; Kyu, Thein; Nosaka, Mami; Kudo, Hiroto; Nishikubo, Tadatomi

    2008-03-01

    Phase behavior of a mixture of eutectic liquid crystals (E7) and hyperbranched polyester (HBPEAc-COOH) has been investigated using polarized optical microscopy and differential scanning calorimetry. The observed phase diagram is an upper azeotrope, exhibiting the coexistence of nematic + isotropic phase in the vicinity of 90˜110^oC above the clearing temperature of neat E7 (60^oC). With decreasing temperature a focal-conic fan shaped texture develops in the composition range of 70˜90 wt% of E7, suggestive of induced smectic Sm-A phase in the mixture containing no known smectic phase in their neat forms. Wide angle x-ray diffraction (WAXD) technique revealed the existence of higher order mesophase(s). The phenomenon of induced mesophase in the hyperbranched polyester/E7 system will be discussed.

  8. Phase-separation transition in liquid mixtures near curved charged objects.

    PubMed

    Marcus, Gilad; Samin, Sela; Tsori, Yoav

    2008-08-14

    We study the thermodynamic behavior of nonpolar liquid mixtures in the vicinity of curved charged objects, such as electrodes or charged colloids. There is a critical value of charge (or potential), above which a phase-separation transition occurs, and the interface between high- and low-dielectric constant components becomes sharp. Analytical and numerical composition profiles are given, and the equilibrium front location as a function of charge or voltage is found. We further employ a simple Cahn-Hilliard type equation to study the dynamics of phase separation in spatially nonuniform electric fields. We find an exponential temporal relaxation of the demixing front location. We give the dependence of the steady-state location and characteristic time on the charge, mixture composition and ambient temperature. PMID:18715044

  9. Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for liquid mixtures

    SciTech Connect

    Ploetz, Elizabeth A.; Smith, Paul E.

    2015-03-07

    Kirkwood-Buff or Fluctuation Solution Theory can be used to provide experimental pair fluctuations, and/or integrals over the pair distribution functions, from experimental thermodynamic data on liquid mixtures. Here, this type of approach is used to provide triplet and quadruplet fluctuations, and the corresponding integrals over the triplet and quadruplet distribution functions, in a purely thermodynamic manner that avoids the use of structure factors. The approach is then applied to binary mixtures of water + methanol and benzene + methanol over the full composition range under ambient conditions. The observed correlations between the different species vary significantly with composition. The magnitude of the fluctuations and integrals appears to increase as the number of the most polar molecule involved in the fluctuation or integral also increases. A simple physical picture of the fluctuations is provided to help rationalize some of these variations.

  10. Liquid-crystal phase diagrams of binary mixtures of hard spherocylinders.

    PubMed

    Cinacchi, Giorgio; Mederos, Luis; Velasco, Enrique

    2004-08-22

    We have built the liquid crystal phase diagram of several binary mixtures of freely rotating hard spherocylinders employing a second-order virial density functional theory with Parsons scaling, suitably generalized to deal with mixtures and smectic phases. The components have the same diameter and aspect ratio of moderate value, typical of many mesogens. Attention has been paid to smectic-smectic demixing and the types of arrangement that rods can adopt in layered phases. Results are shown to depend on the aspect ratio of the individual components and on the ratio of their lengths. Smectic phases are seen not to easily mix together at sufficiently high pressures. Layered phases where the longer rods are the majority component have a smectic-A structure. In the opposite case, a smectic-A(2) phase is obtained where the shorter particles populate the layers and the longer ones prefer to stay parallel to the latter in the interlayer region.

  11. Formation of smectic phases in binary liquid crystal mixtures with a huge length ratio.

    PubMed

    Kapernaum, Nadia; Knecht, Friederike; Hartley, C Scott; Roberts, Jeffrey C; Lemieux, Robert P; Giesselmann, Frank

    2012-01-01

    A system of two liquid-crystalline phenylpyrimidines differing strongly in molecular length was studied. The phase diagram of these two chemically similar mesogens, with a length ratio of 2, was investigated, and detailed X-ray diffraction and electrooptical measurements were performed. The phase diagram revealed a destabilization of the nematic phase, which is present in the pure short compound, while the smectic state was stabilized. The short compound forms smectic A and smectic C phases, whereas the longer compound forms a broad smectic C phase and a narrow higher-ordered smectic phase. Nevertheless, in the mixtures, the smectic C phase is destabilized and disappears rapidly, whereas smectic A is the only stable phase observed over a broad concentration range. In addition, the smectic translational order parameters as well as the tilt angles of the mixtures are reduced. The higher-ordered smectic phase of the longer mesogen was identified as a smectic F phase.

  12. Formation of smectic phases in binary liquid crystal mixtures with a huge length ratio

    PubMed Central

    Knecht, Friederike; Hartley, C Scott; Roberts, Jeffrey C; Lemieux, Robert P; Giesselmann, Frank

    2012-01-01

    Summary A system of two liquid-crystalline phenylpyrimidines differing strongly in molecular length was studied. The phase diagram of these two chemically similar mesogens, with a length ratio of 2, was investigated, and detailed X-ray diffraction and electrooptical measurements were performed. The phase diagram revealed a destabilization of the nematic phase, which is present in the pure short compound, while the smectic state was stabilized. The short compound forms smectic A and smectic C phases, whereas the longer compound forms a broad smectic C phase and a narrow higher-ordered smectic phase. Nevertheless, in the mixtures, the smectic C phase is destabilized and disappears rapidly, whereas smectic A is the only stable phase observed over a broad concentration range. In addition, the smectic translational order parameters as well as the tilt angles of the mixtures are reduced. The higher-ordered smectic phase of the longer mesogen was identified as a smectic F phase. PMID:23019439

  13. Induced smectic phase in mixtures of hyperbranched polyester and liquid crystal mesogens.

    PubMed

    Kim, Namil; Huang, Tsang-Min; Kyu, Thein; Nosaka, Mami; Kudo, Hiroto; Nishikubo, Tadatomi

    2008-10-23

    The phase diagram of a mixture consisting of hyperbranched polyester (HBPEAc-COOH) and eutectic nematic liquid crystals (E7) has been established experimentally by means of differential scanning calorimetry and polarized optical microscopy subjected to prolonged annealing. The observed phase diagram is an upper azeotrope, exhibiting the coexistence of nematic + isotropic phase in the vicinity of 90 approximately 110 degrees C above the clearing temperature of neat E7 (60 degrees C). With decreasing temperature, a focal-conic fan shaped texture develops in the composition range of 63 approximately 93 wt % of the annealed E7/HBPEAc-COOH blends, suggestive of induced smectic phase in the mixture. Wide angle X-ray diffraction (WAXD) technique revealed the existence of higher order mesophase(s).

  14. Coupling Charge Reduction Mass Spectrometry to Liquid Chromatography for Complex Mixture Analysis.

    PubMed

    Stutzman, John R; Crowe, Matthew C; Alexander, James N; Bell, Bruce M; Dunkle, Melissa N

    2016-04-01

    Electrospray ionization (ESI) of solution mixtures often generates complex mass spectra, even following liquid chromatography (LC), due to analyte multiple charging. Multiple charge state distributions can lead to isobaric interferences, mass spectral congestion, and ambiguous ion identification. As a consequence, data interpretation increases in complexity. Several charge reduction mass spectrometry (MS) approaches have been previously developed to reduce the average charge state of gaseous ions; however, all of these techniques have been restricted to direct infusion MS. In this study, synthetic polyols and surfactants separated by liquid chromatography and ionized by positive mode ESI have been subjected to polonium-210 α-particle radiation to reduce the average charge state to singly charged cations prior to mass analysis. LC/MS analysis of 5000 molecular weight poly(ethylene glycol) (PEG5000) generated an average charge state of 5.88+; whereupon, liquid chromatography/electrospray ionization/charge reduction/mass spectrometry (LC/CR/MS) analysis of PEG 5000 generated an average charge state of 1.00+. The PEG5000 results demonstrated a decrease in spectral complexity and enabled facile interpretation. Other complex solution mixtures representing specific MS challenges (i.e., competitive ionization and isobaric ion overlap) were explored and analyzed with LC/CR/MS to demonstrate the benefits of coupling LC to CR/MS. For example, polyol information related to initiator, identity/relative amount of monomer, and estimated molecular weight was characterized in random and triblock ethylene oxide/propylene oxide polyols using LC/CR/MS. LC/CR/MS is a new analytical technique for the analysis of complex mixtures. PMID:26971559

  15. Theoretical Rocket Performance of Liquid Methane with Several Fluorine-Oxygen Mixtures Assuming Frozen Composition

    NASA Technical Reports Server (NTRS)

    Gordon, Sanford; Kastner, Michael E

    1958-01-01

    Theoretical rocket performance for frozen composition during expansion was calculated for liquid methane with several fluorine-oxygen mixtures for a range of pressure ratios and oxidant-fuel ratios. The parameters included are specific impulse, combustion-chamber temperature, nozzle-exit temperature molecular weight, characteristic velocity, coefficient of thrust, ratio of nozzle-exit area to throat area, specific heat at constant pressure, isentropic exponent, viscosity, and thermal conductivity. The maximum calculated value of specific impulse for a chamber pressure of 600 pounds per square inch absolute (40.827atm) and an exit pressure of 1 atmosphere is 315.3 for 79.67 percent fluorine in the oxidant.

  16. Analysis of organic solvents and liquid mixtures using a fiber-tip evaporation sensor

    NASA Astrophysics Data System (ADS)

    Preter, Eyal; Donlagic, Denis; Artel, Vlada; Katims, Rachel A.; Sukenik, Chaim N.; Zadok, Avi

    2014-05-01

    The instantaneous size and rate of evaporation of pendant liquid droplets placed on the cleaved facet of a standard fiber are reconstructed based on reflected optical power. Using the evaporation dynamics, the relative contents of ethanol in ethanol-water binary mixtures are assessed with 1% precision and different blends of methanol in gasoline are properly recognized. The latter application, in particular, is significant for the use of alternative fuels in the automotive sector. Also, ten organic solvents are identified based on their evaporation from a fiber facet coated with a hydrophobic, selfassembled monolayer.

  17. Process and catalyst for converting synthesis gas to liquid hydrocarbon mixture

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1987-01-01

    Synthesis gas containing CO and H.sub.2 is converted to a high-octane hydrocarbon liquid in the gasoline boiling point range by bringing the gas into contact with a heterogeneous catalyst including, in physical mixture, a zeolite molecular sieve, cobalt at 6-20% by weight, and thoria at 0.5-3.9% by weight. The contacting occurs at a temperature of 250.degree.-300.degree. C., and a pressure of 10-30 atmospheres. The conditions can be selected to form a major portion of the hydrocarbon product in the gasoline boiling range with a research octane of more than 80 and less than 10% by weight aromatics.

  18. Impact of Liquid-Vapor to Liquid-Liquid-Vapor Phase Transitions on Asphaltene-Rich Nanoaggregate Behavior in Athabasca Vacuum Residue + Pentane Mixtures

    SciTech Connect

    Long, Bingwen; Chodakowski, Martin; Shaw, John M.

    2013-06-05

    The bulk phase behavior of heavy oil + alkane mixtures and the behavior of the asphaltenes that they contain are topics of importance for the design and optimization of processes for petroleum production, transport, and refining and for performing routine saturates, aromatics, resins, and asphaltenes (SARA) analyses. In prior studies, partial phase diagrams and phase behavior models for Athabasca vacuum residue (AVR) comprising 32 wt % pentane asphaltenes + n-alkanes were reported. For mixtures with pentane, observed phase behaviors included single-phase liquid as well as liquid–liquid, liquid–liquid–vapor, and liquid–liquid–liquid–vapor regions. Dispersed solids were detected under some conditions as well but not quantified. In this work, small-angle X-ray scattering (SAXS) is used to study nanostructured materials in liquid phases present in AVR + n-pentane mixtures from 50 to 170 °C at mixture bubble pressure. The investigation focuses on the impact of the transition from a single AVR-rich liquid to co-existing pentane-rich and AVR-rich liquids on the nanostructure and the nanostructures most resistant to aggregation as the pentane composition axis is approached. Background scattering subtraction was performed using global mixture composition. The robustness of this assumption with respect to values obtained for coefficients appearing in a two level Beaucage unified equation fit is demonstrated. The nanostructured material is shown to arise at two length scales from 1 to 100 wt % AVR. Smaller nanostructures possess mean radii less than 50 Å, while the larger nanostructures possess mean radii greater than 250 Å. The addition of pentane to the AVR causes an increasingly large fraction of the large and small nanostructures to grow in size. Only nanostructures resistant to aggregation remain in the pentane-rich phase as the 0 wt % AVR axis is approached. Step changes in aggregation identified from changes in average radius of gyration, scattering

  19. Excess enthalpy of monoethanolamine + ionic liquid mixtures: how good are COSMO-RS predictions?

    PubMed

    Gonzalez-Miquel, Maria; Massel, Marjorie; DeSilva, Aruni; Palomar, Jose; Rodriguez, Francisco; Brennecke, Joan F

    2014-10-01

    Mixtures of ionic liquids (ILs) and molecular amines have been suggested for CO2 capture applications. The basic idea is to replace water, which volatilizes in the amine regeneration step and increases the parasitic energy load, with a nonvolatile ionic liquid solvent. To fully understand the thermodynamics of these systems, here experimental excess enthalpies for binary mixtures of monoethanolamine (MEA) and two ILs: 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [hmim][NTf2], and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [OHemim][NTf2], were obtained by calorimetry, using a Setaram C80 calorimeter, over the whole range of compositions at 313.15 K. Since it is the temperature derivative of the Gibbs energy, enthalpy is a sensitive measure of intermolecular interactions. MEA + [hmim][NTf2] is endothermic and MEA + [OHemim][NTf2] is exothermic. The reliability of COSMO-RS to predict the excess enthalpy of the (MEA+IL) systems was tested based on the implementation of two different molecular models to define the structure of the IL: the IL as separate cation and anion [C+A] and the IL as a bonded single specie [CA]. Quantum-chemical calculations were performed to gain additional insight into the intermolecular interactions between the components of the mixture. For MEA + [hmim][NTf2] both the [C+A] and [CA] models predict endothermic behavior, but the [CA] model is in better agreement with the experimental results. For MEA + [OHemim][NTf2] the [C+A] model provides the best match to the experimental exothermic results. However, what is really surprising is that two different conformations of the cation-anion pair with nearly identical energies in the [CA] model result in completely different (exothermic vs endothermic) predictions of the excess enthalpy. Nonetheless, the results do show that the influence of the structure of the IL on the thermodynamic behavior of the mixture (endothermic vs exothermic) can be attributed

  20. Comparative study of acoustic relaxation time of cholesteric liquid crystal and mixtures

    NASA Astrophysics Data System (ADS)

    Bhave, Manisha G.; Gharde, Rita; Radha, S.

    2016-09-01

    The present study focuses on the relaxation processes in Cholesteric Liquid Crystal and mixtures. We have dispersed two different monomers in CLC to form Polymer dispersed liquid crystals (PDCLCs). PDLC films have a remarkable electro-optical behavior since they can be switched from highly light scattering state (OFF) to transparent state (ON) simply by application of an electric field. We have also doped ferroelectric nano - powder (NP) in CLC. The phase transitions occurred at temperatures lower than those exhibited by the mesogenic component before doping. The viscosity, ultrasonic velocity and density show variation with change in the material as well as temperature. The acoustic relaxation time and ultrasonic attenuation decrease with increase in temperature for CLC and CLC+NP. The parameters of PDCLC2 in comparison with PDCLC1 are more linear in isotropic and anisotropic regions. For PDCLC2 the values reach maximum value at the Cholesteric-isotropic transition.

  1. Preparation of ibuprofen-loaded liquid suppository using eutectic mixture system with menthol.

    PubMed

    Yong, Chul Soon; Oh, Yu-Kyoung; Jung, Se Hyun; Rhee, Jong-Dal; Kim, Ho-Dong; Kim, Chong-Kook; Choi, Han-Gon

    2004-12-01

    To prepare an ibuprofen-loaded liquid suppository using eutectic mixture with menthol, the effects of menthol and poloxamer 188 (P 188) on the aqueous solubility of ibuprofen were investigated. The physicochemical properties such as gelation temperature, gel strength and bioadhesive force of various formulations composed of ibuprofen, menthol and P 188 were investigated. Then, the pharmacokinetic study of ibuprofen delivered by the liquid suppositories composed of P 188 and menthol were then performed. In the absence of P 188, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts of ibuprofen formed eutectic mixture with six parts of menthol. In the presence of P 188, the solutions with the same ratio showed abrupt increase in the solubility of ibuprofen. Furthermore, the solution with ratio of 4:6 showed more than 2.5- and 6-fold increase in the solubility of ibuprofen compared with that without additives and that without menthol, respectively. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2mg/ml. Ibuprofen increased the gelation temperature and weakened the gel strength and bioadhesive force of liquid suppositories. However, menthol did the opposite due to forming the eutectic mixture with ibuprofen. The ibuprofen-loaded liquid suppository [P 188/menthol/ibuprofen (15/0.25/2.5%)] with the maximum ibuprofen solubility of 1.2mg/ml was administered easily to the anus and to remain at the administered site without leakage after the dose. Furthermore, it gave significantly higher initial plasma concentrations, Cmax and AUC of ibuprofen than did solid suppository, indicating that the drug from poloxamer gel could be more absorbed than that from solid one in rats. Thus, the liquid suppository system with P 188 and menthol, a more

  2. Coarsening in Solid-Liquid Mixtures Studied on the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Caruso, John J.

    1999-01-01

    Ostwald ripening, or coarsening, is a process in which large particles in a two-phase mixture grow at the expense of small particles. It is a ubiquitous natural phenomena occurring in the late stages of virtually all phase separation processes. In addition, a large number of commercially important alloys undergo coarsening because they are composed of particles embedded in a matrix. Many of them, such as high-temperature superalloys used for turbine blade materials and low-temperature aluminum alloys, coarsen in the solid state. In addition, many alloys, such as the tungsten-heavy metal systems, coarsen in the solid-liquid state during liquid phase sintering. Numerous theories have been proposed that predict the rate at which the coarsening process occurs and the shape of the particle size distribution. Unfortunately, these theories have never been tested using a system that satisfies all the assumptions of the theory. In an effort to test these theories, NASA studied the coarsening process in a solid-liquid mixture composed of solid tin particles in a liquid lead-tin matrix. On Earth, the solid tin particles float to the surface of the sample, like ice in water. In contrast, in a microgravity environment this does not occur. The microstructures in the ground- and space-processed samples (see the photos) show clearly the effects of gravity on the coarsening process. The STS-83-processed sample (right image) shows nearly spherical uniformly dispersed solid tin particles. In contrast, the identically processed, ground-based sample (left image) shows significant density-driven, nonspherical particles, and because of the higher effective solid volume fraction, a larger particle size after the same coarsening time. The "Coarsening in Solid-Liquid Mixtures" (CSLM) experiment was conducted in the Middeck Glovebox facility (MGBX) flown aboard the shuttle in the Microgravity Science Laboratory (MSL-1/1R) on STS-83/94. The primary objective of CSLM is to measure the temporal

  3. Near Infrared Spectroscopy of Liquid Hydrocarbon Mixtures for Understanding the Composition of Titan’s Lakes

    NASA Astrophysics Data System (ADS)

    Hadnott, Bryne; Hodyss, Robert; Cable, Morgan; Vu, Tuan; Hayes, Alexander

    2015-11-01

    The presence of ethane and methane lakes on Titan was confirmed by the Cassini Visible and Infrared Mapping Spectrometer (VIMS) data in 2008, and has been investigated in further detail by the Cassini radar instrument (Brown et al, 2008; Pailloue et al, 2008). Modeled compositions suggest that the lakes are predominantly liquid ethane, with liquid methane, propane, and butane; however, pure liquid methane lakes (such as Ligeia Mare) may also be present (Cordier et al, 2009; Mastrogiuseppe et al, 2014). We present a proof-of-concept instrument, consisting of a near infrared (NIR) spectrometer with a fiber optic probe, in order to conduct non-invasive analyses of cryogenic fluids on planetary bodies. To determine the utility of spectroscopy for in-situ studies, we collected transmission spectra of hydrocarbon mixtures, pure methane and ethane endmembers, and nitrogen-saturated hydrocarbons in the NIR region between 900 to 2500 nm; liquid hydrocarbons were measured in a dewar filled with liquid nitrogen, contained within a glove bag pumped with gaseous nitrogen at a total oxygen concentration of < 0.1%. The resultant spectra contained key absorption features that allowed us to determine the relative abundances of each endmember, and the effects temperature and dissolved nitrogen, based on the changes in peak intensity. Peak intensity, as well as integrated absorbance, full-width half-maximum, and peak location were calculated using a multi-peak fitting algorithm; we also adopted a simple linear mixing model which used pure ethane and methane spectra, as well as the measured mixtures, to calculate the linear coefficients of each endmember within the mixture. Resultant plots of changes in peak intensity with temperature (for methane), peak intensity with mole fraction of methane (or ethane), and comparisons of the modeled linear coefficients with the mole fraction of methane (or ethane) added will yield useful data on how methane, ethane, and dissolved nitrogen mix

  4. Surface freezing and molecular miscibility of binary alkane-alkane and fluoroalkane-alkane liquid mixtures.

    PubMed

    Takiue, Takanori; Shimasaki, Mayuko; Tsuura, Miyako; Sakamoto, Hiroyasu; Matsubara, Hiroki; Aratono, Makoto

    2014-02-13

    The surface freezing (SF) of liquid n-heptadecane (C17)-n-octadecane (C18) and 1-perfluorooctyl decane (F8H10)-C18 mixtures were studied by surface tension and external reflection absorption FTIR (ERA-FTIR) measurements. The surface tension versus temperature curves of all pure liquids show a sharp break point at Ts corresponding to a surface liquid (SL)-SF transition. The entropy of surface formation is very negative, indicating a well-ordered structure of the SF layer. The ERA-FTIR spectra in the SF state suggested that the C18 molecules are densely packed in the solid state, while the packing of the hydrocarbon (HC) part of F8H10 is a little looser than the fluorocarbon (FC) part because of the difference in the cross-sectional area. In the C17-C18 mixture, the SL-SF transition was found at all bulk compositions. The estimation of the surface composition suggested that two components are miscible both in SL and SF states. The excess entropy of the surface is almost zero in both states, and thus, it was concluded that the two components are mixed almost ideally at the surface. In the case of the F8H10-C18 system, on the other hand, the SL layer is enriched in F8H10 with lower surface tension than C18 compared to bulk liquid. The surface composition in the SF state is almost zero or unity, indicating that F8H10 and C18 molecules are practically immiscible mainly due to the weak interaction between different components. Furthermore, the negative excess entropy in the SL layer suggests domain formation of F8H10 molecules at the surface. PMID:24447215

  5. High temperatures and high pressures Brillouin scattering studies of liquid H(2)O+CO(2) mixtures.

    PubMed

    Qin, Junfeng; Li, Min; Li, Jun; Chen, Rongyan; Duan, Zhenhao; Zhou, Qiang; Li, Fangfei; Cui, Qiliang

    2010-10-21

    The Brillouin scattering spectroscopy studies have been conducted in a diamond anvil cell for a liquid mixtures composed of 95 mol % H(2)O and 5 mol % CO(2) under high temperatures and pressures. The sound velocity, refractive index, density, and adiabatic bulk modulus of the H(2)O+CO(2) mixtures were determined under pressures up to the freezing point at 293, 453, and 575 K. It is found from the experiment that sound velocities of the liquid mixture are substantially lower than those of pure water at 575 K, but not at lower temperatures. We presented an empirical relation of the density in terms of pressure and temperature. Our results show that liquid H(2)O+CO(2) mixtures are more compressible than water obtained from an existing equation of state of at 453 and 575 K. PMID:20969409

  6. Pressure drop in fully developed, duct flow of dispersed liquid-vapor mixture at zero gravity

    NASA Technical Reports Server (NTRS)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1990-01-01

    The dynamics of steady, fully developed dispersed liquid-vapor flow in a straight duct at 0-g is simulated by flowing water containing n-butyl benzoate droplets. Water and benzoate are immiscible and have identical density at room temperature. The theoretical basis of the simulation is given. Experiments showed that, for a fixed combined flow rate of water and benzoate, the frictional pressure drop is unaffected by large changes in the volume fraction of benzoate drops and their size distribution. Measured power spectra of the static wall pressure fluctuations induced by the turbulent water-benzoate flow also revealed that their dynamics is essentially unaltered by the presence of the droplets. These experimental findings, together with the theoretical analysis, led to the conclusion that the pressure drop in fully developed, dispersed liquid-vapor flow in straight ducts of constant cross section at 0-g is identical to that due to liquid flowing alone at the same total volumetric flow rate of the liquid-vapor mixture and, therefore, can be readily determined.

  7. Calculation of multicomponent chemical equilibria in gas-solid- liquid systems: calculation methods, thermochemical data, and applications to studies of high-temperature volcanic gases with examples from Mount St. Helens

    USGS Publications Warehouse

    Symonds, R.B.; Reed, M.H.

    1993-01-01

    This paper documents the numerical formulations, thermochemical data base, and possible applications of computer programs, SOLVGAS and GASWORKS, for calculating multicomponent chemical equilibria in gas-solid-liquid systems. SOLVGAS and GASWORKS compute simultaneous equilibria by solving simultaneously a set of mass balance and mass action equations written for all gas species and for all gas-solid or gas-liquid equilibria. Examples of gas-evaporation-from-magma and precipitation-with-cooling calculations for volcanic gases collected from Mount St. Helens are shown. -from Authors

  8. A Vapor-Liquid Equilibria Model for Hydrofluorocarbons and Their Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Li, Jin; Sato, Haruki; Yokozeki, Akimichi; Watanabe, Koichi

    A novel thermodynamic model has been proposed so as to calculate the thermodynamic properties at the vapor-liquid coexistence of HFC (hydrofluorocarbon) refrigerants and their binary mixtures. This model has been developed by modifying the Patel-Teja equation, well-known cubic equation of state, for HFC refrigerants, R- 32, R-125, R-134a, and their binary mixtures for temperatures from 220 K to their critical temperatures. The developed model has features in calculating various thermodynamic properties with ease but accurately. The calculated results on the vapor-liquid equilibrium (VLE) properties by the present model illustrate its superiority to the conventional cubic equations of state. A comparison of the proposed model with the so-called modified Benedict-Webb-Rubin (MBWR) model and the multi-term Helmholtz function model confirms equivalent effectiveness and accuracy by the present model and, therefore, it would be concluded that the proposed model is very powerful in various practical application in refrigeration industry.

  9. Modeling the phase behavior in mixtures of pharmaceuticals with liquid or supercritical solvents.

    PubMed

    Tsivintzelis, Ioannis; Economou, Ioannis G; Kontogeorgis, Georgios M

    2009-05-01

    The concept of solubility parameter, which is widely used for the screening of solvents in pharmaceutical applications, is combined with a thermodynamic theory that is able to model systems with large deviations from ideal behavior. The nonrandom hydrogen-bonding (NRHB) theory is applied to model the phase behavior of mixtures of six pharmaceuticals (i.e., ibuprofen, ketoprofen, naproxen, benzoic acid, methyl paraben, and ethyl paraben). The pure fluid parameters of the studied pharmaceuticals were estimated using limited available experimental (or predicted) data on sublimation pressures, liquid densities, and Hansen's solubility parameters. The complex hydrogen-bonding behavior was explicitly accounted for, while the corresponding parameters were adopted from simpler molecules of similar chemical structure or/and fitted to the aforementioned pure fluid properties. In this way, the solubility of the studied pharmaceuticals in liquid solvents was calculated. The average root-mean-square deviation between experimental and calculated solubilities is 0.190 and 0.037 in log(10) units for prediction (calculations without a binary interaction parameter adjustment) and for correlation (calculations using one binary interaction parameter fitted to experimental data), respectively. In addition, using one temperature-independent binary interaction parameter the phase behavior of pharmaceuticals in supercritical CO(2) and ethane was satisfactorily correlated. Finally, preliminary encouraging results are shown concerning two ternary mixtures where the model is able to predict accurately the solubility of pharmaceuticals in mixed solvents based on interaction parameters fitted to corresponding single solvent data. PMID:19368360

  10. Modeling the phase behavior in mixtures of pharmaceuticals with liquid or supercritical solvents.

    PubMed

    Tsivintzelis, Ioannis; Economou, Ioannis G; Kontogeorgis, Georgios M

    2009-05-01

    The concept of solubility parameter, which is widely used for the screening of solvents in pharmaceutical applications, is combined with a thermodynamic theory that is able to model systems with large deviations from ideal behavior. The nonrandom hydrogen-bonding (NRHB) theory is applied to model the phase behavior of mixtures of six pharmaceuticals (i.e., ibuprofen, ketoprofen, naproxen, benzoic acid, methyl paraben, and ethyl paraben). The pure fluid parameters of the studied pharmaceuticals were estimated using limited available experimental (or predicted) data on sublimation pressures, liquid densities, and Hansen's solubility parameters. The complex hydrogen-bonding behavior was explicitly accounted for, while the corresponding parameters were adopted from simpler molecules of similar chemical structure or/and fitted to the aforementioned pure fluid properties. In this way, the solubility of the studied pharmaceuticals in liquid solvents was calculated. The average root-mean-square deviation between experimental and calculated solubilities is 0.190 and 0.037 in log(10) units for prediction (calculations without a binary interaction parameter adjustment) and for correlation (calculations using one binary interaction parameter fitted to experimental data), respectively. In addition, using one temperature-independent binary interaction parameter the phase behavior of pharmaceuticals in supercritical CO(2) and ethane was satisfactorily correlated. Finally, preliminary encouraging results are shown concerning two ternary mixtures where the model is able to predict accurately the solubility of pharmaceuticals in mixed solvents based on interaction parameters fitted to corresponding single solvent data.

  11. The dynamic behavior of a liquid ethanol-water mixture: a perspective from quantum chemical topology.

    PubMed

    Mejía, Sol M; Mills, Matthew J L; Shaik, Majeed S; Mondragon, Fanor; Popelier, Paul L A

    2011-05-01

    Quantum Chemical Topology (QCT) is used to reveal the dynamics of atom-atom interactions in a liquid. A molecular dynamics simulation was carried out on an ethanol-water liquid mixture at its azeotropic concentration (X(ethanol)=0.899), using high-rank multipolar electrostatics. A thousand (ethanol)(9)-water heterodecamers, respecting the water-ethanol ratio of the azeotropic mixture, were extracted from the simulation. Ab initio electron densities were computed at the B3LYP/6-31+G(d) level for these molecular clusters. A video shows the dynamical behavior of a pattern of bond critical points and atomic interaction lines, fluctuating over 1 ns. A bond critical point distribution revealed the fluctuating behavior of water and ethanol molecules in terms of O-H···O, C-H···O and H···H interactions. Interestingly, the water molecule formed one to six C-H···O and one to four O-H···O interactions as a proton acceptor. We found that the more localized a dynamical bond critical point distribution, the higher the average electron density at its bond critical points. The formation of multiple C-H···O interactions affected the shape of the oxygen basin of the water molecule, which is shown in three dimensions. The hydrogen atoms of water strongly preferred to form H···H interactions with ethanol's alkyl hydrogen atoms over its hydroxyl hydrogen.

  12. Pressure in the Landau-Ginzburg functional: Pascal's law, nucleation in fluid mixtures, a meanfield theory of amphiphilic action, and interface wetting in glassy liquids.

    PubMed

    Chan, Ho Yin; Lubchenko, Vassiliy

    2015-09-28

    We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory.

  13. Pressure in the Landau-Ginzburg functional: Pascal's law, nucleation in fluid mixtures, a meanfield theory of amphiphilic action, and interface wetting in glassy liquids

    NASA Astrophysics Data System (ADS)

    Chan, Ho Yin; Lubchenko, Vassiliy

    2015-09-01

    We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory.

  14. Pressure in the Landau-Ginzburg functional: Pascal's law, nucleation in fluid mixtures, a meanfield theory of amphiphilic action, and interface wetting in glassy liquids.

    PubMed

    Chan, Ho Yin; Lubchenko, Vassiliy

    2015-09-28

    We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory. PMID:26429019

  15. Multicomponent fuel vaporization at high pressures.

    SciTech Connect

    Torres, D. J.; O'Rourke, P. J.

    2002-01-01

    We extend our multicomponent fuel model to high pressures using a Peng-Robinson equation of state, and implement the model into KIVA-3V. Phase equilibrium is achieved by equating liquid and vapor fugacities. The latent heat of vaporization and fuel enthalpies are also corrected for at high pressures. Numerical simulations of multicomponent evaporation are performed for single droplets for a diesel fuel surrogate at different pressures.

  16. Vapor-liquid phase coexistence of alkane-carbon dioxide and perfluoroalkane-carbon dioxide mixtures

    SciTech Connect

    Cui, S.T.; Cochran, H.D.; Cummings, P.T. |

    1999-05-27

    Both government and industry are seeking benign substitutes for the many organic solvents used in industry. Solvents are used as media for cleaning, for chemical reactions, and for chemical separation, and most of the solvents used are hazardous to health, safety, and the environment. Supercritical carbon dioxide (SC-CO{sub 2}) is often considered as an ideal solvent substitute, but several important classes of substances -- water and hydrophilic substances; proteins, nucleic acids, and many other biomolecules; and most man-made high polymers, for example -- exhibit very low solubility in SC-CO{sub 2}. The authors carried out a molecular simulation study of the vapor-liquid equilibria of alkane-CO{sub 2} and perfluoroalkane-CO{sub 2} binary mixtures using the Gibbs ensemble Monte Carlo method. They used simple interaction site models and the conventional Lorentz-Berthelot combining rules for the cross interaction between the solute and solvent species with no adjustable parameters to predict the vapor-liquid phase equilibrium of the hexane-CO{sub 2} and perfluorohexane-CO{sub 2} mixtures. The predicted CO{sub 2} mole fraction on the liquid branch is higher than the experimental results by about 10--13%. The gas-phase solubility of hexane and perfluorohexane in CO{sub 2} is generally smaller than the experimental results. The model predicts a higher solubility for the perfluoroalkanes in CO{sub 2} in comparison with alkanes in CO{sub 2}, consistent with experiment. The simulation results suggest that the dispersion interaction and the geometric packing may have a predominant role in accounting for the solubility difference between alkane and pefluoroalkane in CO{sub 2}.

  17. Effect of salt of various concentrations on liquid limit, and hydraulic conductivity of different soil-bentonite mixtures

    NASA Astrophysics Data System (ADS)

    Mishra, Anil Kumar; Ohtsubo, Masami; Li, Loretta Y.; Higashi, Takahiro; Park, Junboum

    2009-05-01

    Effect of the various concentrations of NaCl and CaCl2 on the four different soil-bentonite mixtures has been evaluated. The results show that the liquid limit of the mixtures decreases with an increase in the salt concentration. Liquid limit decreased significantly with an increase in CaCl2 concentration from 0 to 0.1 N. However, a further increase in the concentration did not produce any significant decrease in liquid limit. A quite opposite trend was observed for the NaCl solution. An increase in NaCl concentration from 0 to 0.1 N did not produce any major decrease in the liquid limit, but a further increase in concentration from 0.1 to 1 N decreased the liquid limit significantly. Consolidation tests were carried out on the mixtures to evaluate the effect of mineralogical composition of the bentonite on the hydraulic conductivity ( k) of the mixture in the presence of various salts concentrations. The k for any mixtures was found to be decreasing with decrease in the salt concentration. At relatively low concentration, Ca2+ had more effect on the k in comparison to the same concentration of Na+. However, at 1 N of NaCl and CaCl2 almost an equal value of k was observed. A comparison of the performance of four bentonites showed that the mixture with bentonite having highest exchangeable sodium percentage (ESP) exhibited the lowest k when permeated with de-ionized (DI) water, however, k increased with an increase in the salt concentration. Similarly, mixture with a bentonite of lower ESP exhibited a higher k with DI water but with the increase in the salt concentration alteration in the k, compared to all other mixtures, was relatively less.

  18. Density functional theory of gas-liquid phase separation in dilute binary mixtures

    NASA Astrophysics Data System (ADS)

    Okamoto, Ryuichi; Onuki, Akira

    2016-06-01

    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas Δ {μ\\text{s}} (the Gibbs energy of transfer) is considerably larger than the thermal energy {{k}\\text{B}}T for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by {{k}\\text{B}}Tn2\\ell\\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right) , where n2\\ell is the solute density added in liquid. For \\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right)\\gg 1 , phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  19. Selective Single-Step Separation of a Mixture of Three Metal Ions by a Triphasic Ionic-Liquid-Water-Ionic-Liquid Solvent Extraction System.

    PubMed

    Vander Hoogerstraete, Tom; Blockx, Jonas; De Coster, Hendrik; Binnemans, Koen

    2015-08-10

    In a conventional solvent extraction system, metal ions are distributed between two immiscible phases, typically an aqueous and an organic phase. In this paper, the proof-of-principle is given for the distribution of metal ions between three immiscible phases, two ionic liquid phases with an aqueous phase in between them. Three-liquid-phase solvent extraction allows separation of a mixture of three metal ions in a single step, whereas at least two steps are required to separate three metals in the case of two-liquid-phase solvent extraction. In the triphasic system, the lower organic phase is comprised of the ionic liquid betainium- or choline bis(trifluoromethylsulfonyl)imide, whereas the upper organic phase is comprised of the ionic liquid trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide. The triphasic system was used for the separation of a mixture of tin(II), yttrium(III), and scandium(III) ions. PMID:26178665

  20. Vapor-liquid and vapor-liquid-liquid equilibria of carbon dioxide/n-perfluoroalkane/n-alkane ternary mixtures.

    PubMed

    Colina, Coray M; Gubbins, Keith E

    2005-02-24

    Perfluoroalkanes have numerous applications (e.g., in the medical field and the chemical industry), and their high affinity for carbon dioxide makes them attractive as surfactants and cosolvents. Although research in this area has grown in the past few years, very little phase-equilibrium data is available in the open literature for these systems. In this work, we present, for the first time, predictions of vapor-liquid and vapor-liquid-liquid equilibria of binary and ternary systems of carbon dioxide/n-perfluoroalkane/n-alkane. Our results are based on the SAFT-VR EOS (statistical associating fluid theory of variable range, equation of state), and we study the influence of temperature, pressure, composition, and chain length on the phase diagram. The predicted phase diagrams are based on temperature-independent binary interaction parameters, and no ternary parameters are introduced. Comparisons to the available experimental and molecular simulation data show that the predicted diagrams should provide a good representation of the phase equilibria.

  1. Automated high performance liquid chromatography and liquid scintillation counting determination of pesticide mixture octanol/water partition rates

    SciTech Connect

    Moody, R.P.; Carroll, J.M.; Kresta, A.M.

    1987-12-01

    Two novel methods are reported for measuring octanol/water partition rates of pesticides. A liquid scintillation counting (LSC) method was developed for automated monitoring of /sup 14/C-labeled pesticides partitioning in biphasic water/octanol cocktail systems with limited success. A high performance liquid chromatography (HPLC) method was developed for automated partition rate monitoring of several constituents in a pesticide mixture, simultaneously. The mean log Kow +/- SD determined from triplicate experimental runs were for: 2,4-D-DMA (2,4-dichlorophenoxyacetic acid dimethylamine), 0.65 +/- .17; Deet (N,N-diethyl-m-toluamide), 2.02 +/- .01; Guthion (O,O-dimethyl-S-(4-oxo-1,2,3-benzotriazin-3(4H)-ylmethyl) phosphorodithioate), 2.43 +/- .03; Methyl-Parathion (O,O-dimethyl-O-(p-nitrophenyl) phosphorothioate), 2.68 +/- .05; and Fenitrothion (O,O-dimethyl O-(4-nitro-m-tolyl) phosphorothioate), 3.16 +/- .03. A strong positive linear correlation (r = .9979) was obtained between log Kow and log k' (log Kow = 2.35 (log k') + 0.63). The advantages that this automated procedure has in comparison with the standard manual shake-flask procedure are discussed.

  2. Solvent effects by ionic liquid-water mixtures on the heterogeneous hydrolysis of lignocellulosic biomass with solid catalysts

    NASA Astrophysics Data System (ADS)

    Prosser, Jacob H.

    Ionic liquids are novel solvents proposed as alternatives for the liquid phase catalysis of lignocellulosic biomass because these can molecularly dissolve lignocellulose to high concentrations. However, solvent effects caused by ionic liquids for this application, such as how they shift the kinetics and equilibrium of lignocellulose conversion relative to other solvents, as well as if these change the nature of catalysts used and inhibit catalytic activity or unfavorably alter catalytic selectivity have not been rigorously considered. Additionally, many issues associated with the use of ionic liquids as solvents in lignocellulose conversion arise. Firstly, most ionic liquids readily undergo liquid phase thermal degradation at moderately low temperatures relevant for catalysis. Secondly, solvothermal degradation of solid catalytic materials by ILs can occur and is something not widely evaluated. Furthermore, the catalytic nature of many commonly used catalysts is altered through ion exchange between ionizable surface groups and ionic liquid ions. To understand how hydrophilic imidazolium-based ionic liquids influence the hydrolysis of lignocellulose, I examine with the aid of spectroscopic ellipsometry, UV-Vis spectrophotometry, high performance liquid chromatography, reflectance-small angle x-ray scattering, and powder x-ray diffraction the: (1) thermal degradation of a 1,2,3-trialkylimidzaolium ionic liquid; (2) solvothermal stability of mesoporous silica and gamma-alumina catalytsts; (3) behavior of the hydrolysis reaction of a lignin model compound in 1,2,3-trialkylimidzaolium ionic liquid-water mixtures; and (4) this same reaction catalyzed by gamma-alumina. From my investigations, I discover that: (1) water is able to diminish the thermal degradation of imidazolium ionic liquids when its composition is above about 35 mol% in these mixtures, an effect I propose is from two different mechanisms; (2) mesoporous silica and gamma-alumina are solvothermally stable

  3. Mathematical modeling and microbiological verification of ohmic heating of a multicomponent mixture of particles in a continuous flow ohmic heater system with electric field parallel to flow.

    PubMed

    Kamonpatana, Pitiya; Mohamed, Hussein M H; Shynkaryk, Mykola; Heskitt, Brian; Yousef, Ahmed E; Sastry, Sudhir K

    2013-11-01

    To accomplish continuous flow ohmic heating of a low-acid food product, sufficient heat treatment needs to be delivered to the slowest-heating particle at the outlet of the holding section. This research was aimed at developing mathematical models for sterilization of a multicomponent food in a pilot-scale ohmic heater with electric-field-oriented parallel to the flow and validating microbial inactivation by inoculated particle methods. The model involved 2 sets of simulations, one for determination of fluid temperatures, and a second for evaluating the worst-case scenario. A residence time distribution study was conducted using radio frequency identification methodology to determine the residence time of the fastest-moving particle from a sample of at least 300 particles. Thermal verification of the mathematical model showed good agreement between calculated and experimental fluid temperatures (P > 0.05) at heater and holding tube exits, with a maximum error of 0.6 °C. To achieve a specified target lethal effect at the cold spot of the slowest-heating particle, the length of holding tube required was predicted to be 22 m for a 139.6 °C process temperature with volumetric flow rate of 1.0 × 10(-4) m3/s and 0.05 m in diameter. To verify the model, a microbiological validation test was conducted using at least 299 chicken-alginate particles inoculated with Clostridium sporogenes spores per run. The inoculated pack study indicated the absence of viable microorganisms at the target treatment and its presence for a subtarget treatment, thereby verifying model predictions.

  4. Mathematical modeling and microbiological verification of ohmic heating of a multicomponent mixture of particles in a continuous flow ohmic heater system with electric field parallel to flow.

    PubMed

    Kamonpatana, Pitiya; Mohamed, Hussein M H; Shynkaryk, Mykola; Heskitt, Brian; Yousef, Ahmed E; Sastry, Sudhir K

    2013-11-01

    To accomplish continuous flow ohmic heating of a low-acid food product, sufficient heat treatment needs to be delivered to the slowest-heating particle at the outlet of the holding section. This research was aimed at developing mathematical models for sterilization of a multicomponent food in a pilot-scale ohmic heater with electric-field-oriented parallel to the flow and validating microbial inactivation by inoculated particle methods. The model involved 2 sets of simulations, one for determination of fluid temperatures, and a second for evaluating the worst-case scenario. A residence time distribution study was conducted using radio frequency identification methodology to determine the residence time of the fastest-moving particle from a sample of at least 300 particles. Thermal verification of the mathematical model showed good agreement between calculated and experimental fluid temperatures (P > 0.05) at heater and holding tube exits, with a maximum error of 0.6 °C. To achieve a specified target lethal effect at the cold spot of the slowest-heating particle, the length of holding tube required was predicted to be 22 m for a 139.6 °C process temperature with volumetric flow rate of 1.0 × 10(-4) m3/s and 0.05 m in diameter. To verify the model, a microbiological validation test was conducted using at least 299 chicken-alginate particles inoculated with Clostridium sporogenes spores per run. The inoculated pack study indicated the absence of viable microorganisms at the target treatment and its presence for a subtarget treatment, thereby verifying model predictions. PMID:24245889

  5. Properties of a new liquid desiccant solution - Lithium chloride and calcium chloride mixture

    SciTech Connect

    Ertas, A.; Anderson, E.E.; Kiris, I. )

    1992-09-01

    Desiccants, broadly classified as solid and liquid desiccants, have the property of extracting and retaining moisture from air brought into contact with them. By using either type, moisture in the air is removed and the resulting dry air can be used for air-conditioning or drying purposes. Because of its properties, lithium chloride is the most stable liquid desiccant and has a large dehydration concentration (30% to 45%), but its cost is relatively high ($9.00-13.00 per kg). It is expected that lithium chloride will reduce the relative humidity to as low as 15%. Calcium chloride is the cheapest (45 cents per kg) and most readily available desiccant, but it has the disadvantage of being unstable depending on the air inlet conditions and the concentration of the desiccant in the solution. To stabilize calcium chloride and to decrease the high cost of lithium chloride, the two can be mixed in different weight combinations. The main objective of this research is to measure the physical properties of different combinations of this mixture such as density, viscosity, and vapor pressure which are necessary for analysis of heat and mass transfer in a packed tower desiccant-air contact system. The solubility of this new liquid desiccant under certain temperature-concentrations will also be studied.

  6. Self-aggregation of cationic dimeric surfactants in water-ionic liquid binary mixtures.

    PubMed

    Martín, Victoria Isabel; Rodríguez, Amalia; Laschewsky, André; Moyá, María Luisa

    2014-09-15

    The micellization of four dimeric cationic surfactants ("gemini surfactants") derived from N-dodecyl-N,N,N-trimethylammonium chloride was studied in pure water and in water-ionic liquid (IL) solutions by a wide range of techniques. The dimeric surfactants are distinguished by their rigid spacer groups separating the two surfactant motifs, which range from C3 to C5 in length. In order to minimize organic ion pairing effects as well as the role of the ionic liquids as potential co-surfactants, ILs with inorganic hydrophilic anions and organic cations of limited hydrophobicity were chosen, namely ethyl, butyl, and hexyl-3-imidazolium chlorides. (1)H NMR two-dimensional, 2D, rotating frame nuclear Overhauser effect spectroscopy measurements, ROESY, supported this premise. The spacer nature hardly affects the micellization process, neither in water nor in water-IL solutions. However, it does influence the tendency of the dimeric surfactants to form elongated micelles when surfactant concentration increases. In order to have a better understanding of the ternary water-IL surfactant systems, the micellization of the surfactants was also studied in aqueous NaCl solutions, in water-ethylene glycol and in water-formamide binary mixtures. The combined results show that the ionic liquids play a double role in the mixed systems, operating simultaneously as background electrolytes and as polar organic solvents. The IL role as organic co-solvent becomes more dominant when its concentration increases, and when the IL alkyl chain length augments.

  7. A Simple Technique of Liquid Purity Analysis and Its Application to Analysis of Water Concentration in Alcohol-Water Mixtures

    NASA Astrophysics Data System (ADS)

    de, Dilip; Aziz de, Abdul

    2012-10-01

    The change of activation energy of a liquid molecule and hence its viscosity coefficient with addition of contaminants to the original liquid gives rise to a new technology for analysis of purity of the liquid. We discovered that concentration of certain contaminants such as water in alcohol or vice versa can be uniquely and accurately determined in a short time (about 10-15 minutes) using a simple and yet innovative technique that only requires measurement of time of flow of the impure liquid (say, water-alcohol mixture) and distilled water through a simple viscometer. We determined the increase of activation energy of alcohol molecules with increase of water concentration for ethyl and methyl alcohol. Our detailed investigation on the alcohol-water mixtures along with discussion on possible future potential application of the simple and very reliable inexpensive technique for liquid purity analysis is presented. We compared our present method with other methods on the accuracies, problems and reliability of impurity analysis in liquids. We also discuss a part of the quantum theory of viscosity of liquid mixtures that is in the developmental stage.

  8. Binary Solvent Organization at Silica/Liquid Interfaces: Preferential Ordering in Acetonitrile-Methanol Mixtures.

    PubMed

    Gobrogge, Eric A; Walker, Robert A

    2014-08-01

    Nonlinear vibrational spectroscopy experiments examined solvent organization at the silica/binary solvent interface where the binary solvent consisted of methanol and acetonitrile in varying mole fractions. Data were compared with surface vibrational spectra acquired from silica surfaces exposed to a vapor phase saturated with the same binary solvent mixtures. Changes in vibrational band intensities suggest that methanol ideally adsorbs to the silica/vapor interface but acetonitrile accumulates in excess relative to vapor-phase composition. At the silica/liquid interface, acetonitrile's signal increases until a solution phase mole fraction of ∼0.85. At higher acetonitrile concentrations, acetonitrile's signal decreases dramatically until only a weak signature persists with the neat solvent. This behavior is ascribed to dipole-paired acetonitrile forming a bilayer with the first sublayer associating with surface silanol groups and a second sublayer consisting of weakly associating, antiparallel partners. On the basis of recent simulations, we propose that the second sublayer accumulates in excess. PMID:26277964

  9. Atomistic Insight into Tetraalkylphosphonium Bis(oxalato)borate Ionic Liquid/Water Mixtures. 2. Volumetric and Dynamic Properties.

    PubMed

    Wang, Yong-Lei; Shimpi, Manishkumar R; Sarman, Sten; Antzutkin, Oleg N; Glavatskih, Sergei; Kloo, Lars; Laaksonen, Aatto

    2016-08-01

    Atomistic molecular dynamics simulations have been performed to investigate volumetric quantities and dynamic properties of binary trihexyltetradecylphosphonium bis(oxalato)borate ([P6,6,6,14][BOB]) ionic liquid (IL)/water mixtures with different water concentrations. The predicted liquid densities for typical [P6,6,6,14][BOB] IL/water mixtures are consistent with available experimental data with a relative discrepancy of less than 3%. The liquid densities and excess molar volumes of all studied [P6,6,6,14][BOB] IL/water mixtures are characterized by concave and convex features, respectively, within full water concentration range. The dynamic properties of [P6,6,6,14] cations, [BOB] anions, and water molecules are particularly analyzed through calculation of velocity autocorrelation functions, diffusion coefficients, and reorientational autocorrelation functions and correlation times. The translational and reorientational mobilities of three species become faster upon increasing water concentration in [P6,6,6,14][BOB] IL/water mixtures and present complex dynamical characteristics arising from three distinct microscopic diffusion features within the full water concentration range. The obtained striking volumetric quantities and particular dynamic properties are well correlated to microscopic liquid structural organization and distinct local ionic environment of all studied [P6,6,6,14][BOB] IL/water mixtures.

  10. Mathematical methods for restricted domain ternary liquid mixture free energy determination using light scattering.

    PubMed

    Wahle, Chris W; Ross, David S; Thurston, George M

    2013-09-28

    We extend methods of solution of a light scattering partial differential equation for the free energy of mixing to apply to connected, isotropic ternary liquid composition domains that do not touch all three binary axes. To do so we mathematically analyze the problem of inferring needed Dirichlet boundary data, and solving for the free energy, with use of hypothetical static light scattering measurements that correspond to dielectric composition gradient vectors that have distinct directions. The physical idea behind the technique is that contrasting absorption properties of mixture components can result in such distinctly directed dielectric composition gradient vectors, due to their differing wavelength dependences of dielectric response. At suitably chosen wavelengths, contrasting light scattering efficiency patterns in the ternary composition triangle can then correspond to the same underlying free energy, and enlarge the scope of available information about the free energy, as shown here. We show how to use distinctly directed dielectric gradients to measure the free energy on both straight lines and curves within the ternary composition triangle, so as to provide needed Dirichlet conditions for light scattering partial differential equation solution. With use of Monte Carlo simulations of noisy light scattering data, we provide estimates of the overall system measurement time and sample spacing needed to determine the free energy to a desired degree of accuracy, for various angles between the assumed dielectric gradient vectors, and indicate how the measurement time depends on instrumental throughput parameters. The present analysis methods provide a way to use static light scattering to measure, directly, mixing free energies of many systems that contain such restricted liquid domains, including aqueous solutions of biological macromolecules, micellar mixtures and microemulsions, and many small molecule systems that are important in separation technology.

  11. Mathematical methods for restricted domain ternary liquid mixture free energy determination using light scattering

    NASA Astrophysics Data System (ADS)

    Wahle, Chris W.; Ross, David S.; Thurston, George M.

    2013-09-01

    We extend methods of solution of a light scattering partial differential equation for the free energy of mixing to apply to connected, isotropic ternary liquid composition domains that do not touch all three binary axes. To do so we mathematically analyze the problem of inferring needed Dirichlet boundary data, and solving for the free energy, with use of hypothetical static light scattering measurements that correspond to dielectric composition gradient vectors that have distinct directions. The physical idea behind the technique is that contrasting absorption properties of mixture components can result in such distinctly directed dielectric composition gradient vectors, due to their differing wavelength dependences of dielectric response. At suitably chosen wavelengths, contrasting light scattering efficiency patterns in the ternary composition triangle can then correspond to the same underlying free energy, and enlarge the scope of available information about the free energy, as shown here. We show how to use distinctly directed dielectric gradients to measure the free energy on both straight lines and curves within the ternary composition triangle, so as to provide needed Dirichlet conditions for light scattering partial differential equation solution. With use of Monte Carlo simulations of noisy light scattering data, we provide estimates of the overall system measurement time and sample spacing needed to determine the free energy to a desired degree of accuracy, for various angles between the assumed dielectric gradient vectors, and indicate how the measurement time depends on instrumental throughput parameters. The present analysis methods provide a way to use static light scattering to measure, directly, mixing free energies of many systems that contain such restricted liquid domains, including aqueous solutions of biological macromolecules, micellar mixtures and microemulsions, and many small molecule systems that are important in separation technology.

  12. Structure and dynamics of binary liquid mixtures near their continuous demixing transitions

    NASA Astrophysics Data System (ADS)

    Roy, Sutapa; Dietrich, S.; Höfling, Felix

    2016-10-01

    The dynamic and static critical behavior of a family of binary Lennard-Jones liquid mixtures, close to their continuous demixing points (belonging to the so-called model H' dynamic universality class), are studied computationally by combining semi-grand canonical Monte Carlo simulations and large-scale molecular dynamics (MD) simulations, accelerated by graphic processing units (GPU). The symmetric binary liquid mixtures considered cover a variety of densities, a wide range of compressibilities, and various interactions between the unlike particles. The static quantities studied here encompass the bulk phase diagram (including both the binodal and the λ-line), the correlation length, and the concentration susceptibility, of the finite-sized systems above the bulk critical temperature Tc, the compressibility and the pressure at Tc. Concerning the collective transport properties, we focus on the Onsager coefficient and the shear viscosity. The critical power-law singularities of these quantities are analyzed in the mixed phase (above Tc) and non-universal critical amplitudes are extracted. Two universal amplitude ratios are calculated. The first one involves static amplitudes only and agrees well with the expectations for the three-dimensional Ising universality class. The second ratio includes also dynamic critical amplitudes and is related to the Einstein-Kawasaki relation for the interdiffusion constant. Precise estimates of this amplitude ratio are difficult to obtain from MD simulations, but within the error bars our results are compatible with theoretical predictions and experimental values for model H'. Evidence is reported for an inverse proportionality of the pressure and the isothermal compressibility at the demixing transition, upon varying either the number density or the repulsion strength between unlike particles.

  13. Double-critical-point phenomena in three-component liquid mixtures: Light-scattering investigations

    NASA Astrophysics Data System (ADS)

    Prafulla, B. V.; Narayanan, T.; Kumar, A.

    1992-12-01

    Measurements of osmotic compressibility (near the lower consolute point, TL) in two reentrant liquid mixtures [3-methylpyridine (MP)+water (W)+heavy water (HW) and MP+W+NaCl] are presented. The closest approach to the double critical point (DCP) was marked by a sample of loop size (ΔT)=250 mK. Analyzing the data by means of the conventional field variable t[=\\|(Tc-T)/Tc\\|] yielded an exact doubling of the critical exponent (CE) γ for a ΔT=250 mK. The approach to double criticality (for intermediate ΔT) is described by a crossover of the CE from the doubled to its single limit as t-->0. Recourse to a more appropriate field variable, tUL[=\\|(TU-T)(TL-T)/TUTL\\|], restores the Ising value of γ(=1.24) for any ΔT. The salt-doped mixtures permitted us to observe a doubling of the extended scaling exponent (Δ) and also to scrutinize the ionic critical phenomena. The range of simple scaling in MP+W+HW was found to be extremely large. Switching to a modified variable t'UL[=\\|(TU-T)(TL-T)/T2\\|] led to a remarkable enhancement in the weight of the extended scaling term in both the mixtures-in apparent disagreement with the earlier findings that reported a widening of the asymptotic region. Non-phase-separating samples of MP+W+HW showed the expected saturating divergence preceded by a region of doubled γ as TD (DCP temperature) was neared. Most of the facets of our investigations can be comprehended in terms of the geometrical picture of phase transitions as well as the Landau-Ginzburg theory as applied to the reentrant phase transitions.

  14. Simultaneous quantitative trace analysis of anionic and nonionic surfactant mixtures by reversed-phase liquid chromatography.

    PubMed

    Portet, F I; Treiner, C; Desbène, P L

    2000-05-01

    The aim of this work was to simultaneously analyse mixtures of a polydisperse polyethylene oxide (PEO) nonionic surfactant and an anionic surfactant (sodium dodecylsulphate, SDS) in water containing sodium chloride in order to quantify trace amounts of these mixtures after their adsorption at water-solid interfaces. A fractional factorial design was then used to optimise the separation by ion-pair reversed-phase liquid chromatography as a function of six factors: the chain length of the tetraalkylammonium salt used as ion-pairing reagent which varied from methyl (C1) to n-propyl (C3); the concentration of this ion-pairing salt; the acetonitrile percentage in water used as organic modifier; the flow-rate; the temperature of analysis and also the sodium chloride concentration. The factorial design enabled in a limited number of analyses, not only to determine which factors had significant effects on retention times or on resolution between a pair of nonionic oligomers, but also to modelize and then find the interesting and rugged area where this resolution was optimal as well as the conditions where time of analysis was not prohibitive. After optimisation of HPLC analysis, we used a trace enrichment procedure to quantify very low concentrations of SDS and C12E9 polydisperse PEO in water. A C18 cartridge and a strong anionic exchange cartridge were coupled and the conditions of elution were optimised in order to obtain concentrated samples which were injected in the same eluent than the HPLC mobile phase. Under such conditions, we were able to quantify, in a single run, mixtures of anionic and nonionic surfactants at concentrations as low as 3.6 microg l(-1) for SDS and 2.5 microg l(-1) for each PEO oligomer in water. PMID:10843549

  15. Coarsening in Solid-Liquid Mixtures-2: A Materials Science Experiment for the ISS

    NASA Technical Reports Server (NTRS)

    Hickman, J. Mark; Voorhees, Peter W.; Kwon, Yongwoo; Lorik, Tibor

    2004-01-01

    A materials science experiment has been developed and readied for operation aboard the International Space Station (ISS). Components of this experiment are onboard ISS and area awaiting the flight of science samples. The goal of the experiment is to understand the dynamics of Ostwald ripening, also known as coarsening, a process that occurs in nearly any two-phase mixture found in nature. Attempts to obtain experimental data in ground-based laboratories are hindered due to the presence of gravity, which introduces material transport modes other than that of the coarsening phenomenon. This introduces adjustable parameters in the formulation of theory. The original Coarsening in Solid-Liquid Mixtures (CSLM) mission, which flew on the Space Shuttle in 1997, produced data from a coarsened eutectic alloy. Unfortunately, both the science matrix and the hardware, while nominally functional, did not account adequately for operations in microgravity. A significantly redesigned follow-on experiment, CSLM-2 has been developed to redress the inadequacies of the original experiment. This paper reviews the CSLM-2 project: its history, science goals, flight hardware implementation, and planned operations and analysis

  16. Simultaneous determination of potassium clavulanate and cefixime in synthetic mixtures by high-performance liquid chromatography.

    PubMed

    Khan, Islam Ullah; Sharif, Shahzad; Ashfaq, Muhammad; Asghar, Muhammad Nadeem

    2008-01-01

    A simple, precise, and sensitive high-performance liquid chromatographic method was developed and validated for the simultaneous determination of potassium clavulanate and cefixime in synthetic mixture form. The analytes were separated on a C18 column by using 0.03 M disodium hydrogen phosphate buffer (pH 6.5)-methanol (84 + 16, v/v) as the mobile phase with detection at 220 nm. The method exhibited high sensitivity and good linearity in the concentration ranges of 12.5-62.5 and 20-100 microg/mL for potassium clavulanate and cefixime, respectively. The total run time for the 2 components was <8 min, and the average recovery was >101.5% with a relative standard deviation of <1.0%. The proposed method was validated according to guidelines of the International Conference on Harmonization by evaluation of linearity, recovery, selectivity, robustness, limits of detection and quantitation, and within- and between-day precision. The results obtained for the synthetic mixture show that the method is highly precise and accurate for the simultaneous determination of potassium clavulanate and cefixime.

  17. Automated two-dimensional liquid chromatographic system for mapping proteins in highly complex mixtures.

    PubMed

    Isobe, T; Uchida, K; Taoka, M; Shinkai, F; Manabe, T; Okuyama, T

    1991-12-27

    An automated two-dimensional liquid chromatographic system was developed for systematic protein separations which could serve for analytical mapping and preparative separations of proteins. The system applies the principles of the column-switching technique, and consists of two different columns connected in tandem through an electrical column switching valve, two pumping systems to operate each column independently and a system controller to perform sequential chromatography on the two columns. A protein mixture is applied to the first-dimensional anion-exchange column and is separated by stepwise elution with an increasing sodium chloride concentration. The eluent is introduced directly to the second-dimensional reversed-phase column, and is further separated by gradient elution with an increasing acetonitrile concentration. The two elution stages are synchronized by a computer program. By this system, very complex protein mixtures such as crude cerebellar extracts were resolved reproducibly into ca. 200 peaks within 12 h. The method can be used for the total analysis of proteins in various tissues and cells without complicated premanupulation of samples, and allows the simultaneous analysis of a protein isolated by chromatography. The isolated protein is most suitable for use in the strategy of protein and gene sequence analysis.

  18. Detection of a new 'nematic-like' phase in liquid crystal-amphiphile mixture by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Dan, Kaustabh; Roy, Madhusudan; Datta, Alokmay

    2014-04-01

    Differential Scanning Calorimetry (DSC) studies on phase transitions of the pure liquid crystalline material N-4-methoxybenzylidene-4-butylaniline (MBBA) and mixtures of MBBA and the amphiphile Stearic Acid (StA) show significant changes in the behavior of mixture from pure MBBA, as regards the nematic-isotropic (N-I) transition temperature (Tc) and other thermodynamic parameters like enthalpy, specific heat and activation energy with concentration of StA. In particular, the convexity of the Arrhenius plot in pure MBBA vanishes with StA concentration pointing to the formation of a new, perhaps 'nematic-like', phase in the mixtures.

  19. Detection of a new 'nematic-like' phase in liquid crystal-amphiphile mixture by differential scanning calorimetry

    SciTech Connect

    Dan, Kaustabh Roy, Madhusudan Datta, Alokmay

    2014-04-24

    Differential Scanning Calorimetry (DSC) studies on phase transitions of the pure liquid crystalline material N-4-methoxybenzylidene-4-butylaniline (MBBA) and mixtures of MBBA and the amphiphile Stearic Acid (StA) show significant changes in the behavior of mixture from pure MBBA, as regards the nematic-isotropic (N-I) transition temperature (T{sub c}) and other thermodynamic parameters like enthalpy, specific heat and activation energy with concentration of StA. In particular, the convexity of the Arrhenius plot in pure MBBA vanishes with StA concentration pointing to the formation of a new, perhaps 'nematic-like', phase in the mixtures.

  20. Liquid crystalline phases and their dispersions in aqueous mixtures of glycerol monooleate and glyceryl monooleyl ether.

    PubMed

    Popescu, Georgeta; Barauskas, Justas; Nylander, Tommy; Tiberg, Fredrik

    2007-01-16

    The aqueous phase behavior of mixtures of 1-glycerol monooleate (GMO) and its ether analogue, 1-glyceryl monooleyl ether (GME) has been investigated by a combination of polarized microscopy, X-ray diffraction, and NMR techniques. Three phase diagrams of the ternary GMO/GME/water system have been constructed at 25, 40, and 55 degrees C. The results demonstrate that the increasing amount of GME favors the formation of the reversed phases, evidenced by the transformation of the lamellar and bicontinuous cubic liquid crystalline phases of the binary GMO/water system into reversed micellar or reversed hexagonal phases. For a particular liquid crystalline phase, increasing the GME content has no effect on the structural characteristics and hydration properties, thus suggesting ideal mixing with GMO. Investigations of dispersed nanoparticle samples using shear and a polymeric stabilizer, Pluronic F127, show the possibility of forming two different kinds of bicontinuous cubic phase nanoparticles by simply changing the GMO/GME ratio. Also NMR self-diffusion measurements confirm that the block copolymer, Pluronic F127, used to facilitate dispersion formation, is associated with nanoparticles and provides steric stabilization.

  1. Interactions of Aqueous Imidazolium-Based Ionic Liquid Mixtures with Solid-Supported Phospholipid Vesicles

    PubMed Central

    Losada-Pérez, Patricia; Khorshid, Mehran; Renner, Frank Uwe

    2016-01-01

    Despite the environmentally friendly reputation of ionic liquids (ILs), their safety has been recently questioned given their potential as cytotoxic agents. The fundamental mechanisms underlying the interactions between ILs and cells are less studied and by far not completely understood. Biomimetic films are here important biophysical model systems to elucidate fundamental aspects and mechanisms relevant for a large range of biological interaction ranging from signaling to drug reception or toxicity. Here we use dissipative quartz crystal microbalance QCM-D to examine the effect of aqueous imidazolium-based ionic liquid mixtures on solid-supported biomimetic membranes. Specifically, we assess in real time the effect of the cation chain length and the anion nature on a supported vesicle layer of the model phospholipid DMPC. Results indicate that interactions are mainly driven by the hydrophobic components of the IL, which significantly distort the layer and promote vesicle rupture. Our analyses evidence the gradual decrease of the main phase transition temperature upon increasing IL concentration, reflecting increased disorder by weakening of lipid chain interactions. The degree of rupture is significant for ILs with long hydrophobic cation chains and large hydrophobic anions whose behavior is reminiscent of that of antimicrobial peptides. PMID:27684947

  2. Coarsening in Solid-liquid Mixtures: Overview of Experiments on Shuttle and ISS

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.; Hawersaat, Robert W.; Lorik, T.; Thompson, J.; Gulsoy, B.; Voorhees, P. W.

    2013-01-01

    The microgravity environment on the Shuttle and the International Space Station (ISS) provides the ideal condition to perform experiments on Coarsening in Solid-Liquid Mixtures (CSLM) as deleterious effects such as particle sedimentation and buoyancy-induced convection are suppressed. For an ideal system such as Lead-Tin in which all the thermophysical properties are known, the initial condition in microgravity of randomly dispersed particles with local clustering of solid Tin in eutectic liquid Lead-Tin matrix, permitted kinetic studies of competitive particle growth for a range of volume fractions. Verification that the quenching phase of the experiment had negligible effect of the spatial distribution of particles is shown through the computational solution of the dynamical equations of motion, thus insuring quench-free effects from the coarsened microstructure measurements. The low volume fraction experiments conducted on the Shuttle showed agreement with transient Ostwald ripening theory, and the steady-state requirement of LSW theory was not achieved. More recent experiments conducted on ISS with higher volume fractions have achieved steady-state condition and show that the kinetics follows the classical diffusion limited particle coarsening prediction and the measured 3D particle size distribution becomes broader as predicted from theory.

  3. Ionic liquid crystalline phases in 3-hexadecylimidazolium bromide and binary mixtures with 1-decanol.

    PubMed

    Li, Cuihua; He, Jinhua; Chen, Jiahui; Liu, Jianhong; Zhang, Qianling; Yu, Zhenqiang

    2011-07-15

    3-Hexadecylimidazolium bromide was synthesized and characterized showing formation of thermotropic smectic liquid crystals at temperatures above its melting point from 48.5 to 150.9°C. With decreasing temperature, the peak intensities in XRD patterns increase and full widths at half-maximum decrease, suggesting structural order increases with decreasing temperature. Compared with 1,2-dimethyl-3-hexadecyl-imidazolium bromide and hexafluorophosphate, the IL shows a lower melting point and less degree of chain interdigitation. The main reason is due to a more symmetrical structure and denser assembly of the IL molecules, which results in more steric resistance for the alkyl chain to interdigitate. The self-assembly behavior of the hydrophobic IL in an organic solvent was investigated showing SmA(2) lyotropic liquid crystalline phases. The first-order scattering peak shifts to lower q values with increasing IL content, which is opposite to the shift directions of the binary mixtures of the soluble imidazolium IL and water, indicating a different packing behavior of the hydrophobic IL in 1-decanol.

  4. Vapor-Liquid Equilibrium in the Mixture Trichloromethane CHCl3 + C6H10O Cyclohexanone (EVLM1111, LB5654_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Trichloromethane CHCl3 + C6H10O Cyclohexanone (EVLM1111, LB5654_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

  5. Vapor-Liquid Equilibrium in the Mixture Bromotrifluoromethane CBrF3 + CHClF2 Chlorodifluoromethane (EVLM1311, LB5620_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture Bromotrifluoromethane CBrF3 + CHClF2 Chlorodifluoromethane (EVLM1311, LB5620_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

  6. Mixtures of n-octyl-beta-D-glucoside and triethylene glycol mono-n-octyl ether: phase behavior and micellar structure near the liquid-liquid phase boundary.

    PubMed

    Santonicola, Gabriella M; Kaler, Eric W

    2005-10-25

    The phase behavior and microstructure of aqueous mixtures of n-octyl-beta-D-glucoside (C8betaG1) and triethylene glycol mono-n-octyl ether (C8E3) is presented. C8betaG1 forms a one-phase micellar solution in water at surfactant concentrations up to 60 wt %, whereas mixtures with C8E3 show a liquid-liquid phase transition at low surfactant concentration. The position of this phase boundary for mixtures can be rationally shifted in the temperature-composition window by altering the ratio of the two surfactants. Small-angle neutron scattering is used to determine the size and shape of the mixed micelles and to characterize the nature of the fluctuations near the cloud point of the micellar solutions. The C8betaG1/C8E3 solutions are characterized by concentration fluctuations that become progressively stronger upon approach to the liquid-liquid phase boundary, whereas micellar growth is negligible. Such observations confirm previous views of the role of the surfactant phase boundary in tuning attractive micellar interactions, which can be used effectively to change the nature and strength of interparticle interactions in colloidal dispersions. Colloidal silica particles were then added to these surfactant mixtures and were found to aggregate at conditions near the cloud point. This finding is relevant to current strategies for protein crystallization.

  7. ETHANOL, ACETIC ACID, AND WATER ADSORPTION FROM BINARY AND TERNARY LIQUID MIXTURES ON HIGH-SILICA ZEOLITES

    EPA Science Inventory

    Adsorption isotherms were measured for ethanol, acetic acid, and water adsorbed on high-silica ZSM-5 zeolite powder from binary and ternary liquid mixtures at room temperature. Ethanol and water adsorption on two high-silica ZSM-5 zeolites with different aluminum contents and a h...

  8. Shear viscosity of nematic liquid crystals in the vicinity of the smectic-A phase in alkyloxycyanobiphenyl mixtures.

    PubMed

    Jadzyn, J; Czechowski, G

    2001-11-01

    The paper presents a singular temperature behavior of the shear viscosity measured for freely flowing nematic liquid crystals in vicinity to smectic-A phase in n-octyloxycyanobiphenyl and n-hexyloxycyanobiphenyl mixtures--a system exhibiting the reentrant nematic phase.

  9. TMVOC, A Numerical Simulator for Three-Phase Non-isothermal Flowsof Multicomponent Hydrocarbon Mixtures in Variably SaturatedHeterogeneous Media

    SciTech Connect

    Pruess, Karsten; Battistelli, Alfredo

    2005-08-20

    TMVOC is designed for studying subsurface contamination by volatile organic compounds (VOCs), such as hydrocarbon fuels and industrial solvents. It can model the one-, two-, or three-dimensional migration of non-aqueous phase liquids (NAPLs) through the unsaturated and saturated zones, the formation of an oil lens on the water table, the dissolution and subsequent transport of VOCs in groundwater, as well as the vaporization and migration of VOCs in the interstitial air of the unsaturated zone, and the reversible sorption of VOCs on the rock matrix of a porous medium. TMVOC accounts for differences in aqueous solubility and volatility of different VOCs that may be present in a NAPL. Thermal remediation treatments such as steam injection or electric resistance heating and associated phase change and flow effects can also be modeled. A simple half-life model for biodegradation is included as well.

  10. Mixtures of the 1-ethyl-3-methylimidazolium acetate ionic liquid with different inorganic salts: insights into their interactions.

    PubMed

    Oliveira, Filipe S; Cabrita, Eurico J; Todorovic, Smilja; Bernardes, Carlos E S; Lopes, José N Canongia; Hodgson, Jennifer L; MacFarlane, Douglas R; Rebelo, Luís P N; Marrucho, Isabel M

    2016-01-28

    In this work, we explore the interactions between the ionic liquid 1-ethyl-3-methylimidazolim acetate and different inorganic salts belonging to two different cation families, those based on ammonium and others based on sodium. NMR and Raman spectroscopy are used to screen for changes in the molecular environment of the ions in the ionic liquid + inorganic salt mixtures as compared to pure ionic liquid. The ion self-diffusion coefficients are determined from NMR data, allowing the discussion of the ionicity values of the ionic liquid + inorganic salt mixtures calculated using different methods. Our data reveal that preferential interactions are established between the ionic liquid and ammonium-based salts, as opposed to sodium-based salts. Computational calculations show the formation of aggregates between the ionic liquid and the inorganic salt, which is consistent with the spectroscopic data, and indicate that the acetate anion of the ionic liquid establishes preferential interactions with the ammonium cation of the inorganic salts, leaving the imidazolium cation less engaged in the media. PMID:26725329

  11. Lubrication of starch in ionic liquid-water mixtures: Soluble carbohydrate polymers form a boundary film on hydrophobic surfaces.

    PubMed

    Yakubov, Gleb E; Zhong, Lei; Li, Ming; Boehm, Michael W; Xie, Fengwei; Beattie, David A; Halley, Peter J; Stokes, Jason R

    2015-11-20

    Soluble starch polymers are shown to enhance the lubrication of ionic liquid-water solvent mixtures in low-pressure tribological contacts between hydrophobic substrates. A fraction of starch polymers become highly soluble in 1-ethyl-3-methylimidazolium acetate (EMIMAc)-water solvents with ionic liquid fraction ≥60wt%. In 65wt% EMIMAc, a small amount of soluble starch (0.33wt%) reduces the boundary friction coefficient by up to a third in comparison to that of the solvent. This low-friction is associated with a nanometre thick film (ca. 2nm) formed from the amylose fraction of the starch. In addition, under conditions where there is a mixture of insoluble starch particles and solubilised starch polymers, it is found that the presence of dissolved amylose enhances the lubrication of starch suspensions between roughened substrates. These findings open up the possibility of utilising starch biopolymers, as well as other hydrocolloids, for enhancing the performance of ionic liquid lubricants.

  12. Lubrication of starch in ionic liquid-water mixtures: Soluble carbohydrate polymers form a boundary film on hydrophobic surfaces.

    PubMed

    Yakubov, Gleb E; Zhong, Lei; Li, Ming; Boehm, Michael W; Xie, Fengwei; Beattie, David A; Halley, Peter J; Stokes, Jason R

    2015-11-20

    Soluble starch polymers are shown to enhance the lubrication of ionic liquid-water solvent mixtures in low-pressure tribological contacts between hydrophobic substrates. A fraction of starch polymers become highly soluble in 1-ethyl-3-methylimidazolium acetate (EMIMAc)-water solvents with ionic liquid fraction ≥60wt%. In 65wt% EMIMAc, a small amount of soluble starch (0.33wt%) reduces the boundary friction coefficient by up to a third in comparison to that of the solvent. This low-friction is associated with a nanometre thick film (ca. 2nm) formed from the amylose fraction of the starch. In addition, under conditions where there is a mixture of insoluble starch particles and solubilised starch polymers, it is found that the presence of dissolved amylose enhances the lubrication of starch suspensions between roughened substrates. These findings open up the possibility of utilising starch biopolymers, as well as other hydrocolloids, for enhancing the performance of ionic liquid lubricants. PMID:26344308

  13. Dielectric relaxation in ionic liquid/dipolar solvent binary mixtures: A semi-molecular theory.

    PubMed

    Daschakraborty, Snehasis; Biswas, Ranjit

    2016-03-14

    A semi-molecular theory is developed here for studying dielectric relaxation (DR) in binary mixtures of ionic liquids (ILs) with common dipolar solvents. Effects of ion translation on DR time scale, and those of ion rotation on conductivity relaxation time scale are explored. Two different models for the theoretical calculations have been considered: (i) separate medium approach, where molecularities of both the IL and dipolar solvent molecules are retained, and (ii) effective medium approach, where the added dipolar solvent molecules are assumed to combine with the dipolar ions of the IL, producing a fictitious effective medium characterized via effective dipole moment, density, and diameter. Semi-molecular expressions for the diffusive DR times have been derived which incorporates the effects of wavenumber dependent orientational static correlations, ion dynamic structure factors, and ion translation. Subsequently, the theory has been applied to the binary mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) with water (H2O), and acetonitrile (CH3CN) for which experimental DR data are available. On comparison, predicted DR time scales show close agreement with the measured DR times at low IL mole fractions (x(IL)). At higher IL concentrations (x(IL) > 0.05), the theory over-estimates the relaxation times and increasingly deviates from the measurements with x(IL), deviation being the maximum for the neat IL by almost two orders of magnitude. The theory predicts negligible contributions to this deviation from the x(IL) dependent collective orientational static correlations. The drastic difference between DR time scales for IL/solvent mixtures from theory and experiments arises primarily due to the use of the actual molecular volume (V(mol)(dip)) for the rotating dipolar moiety in the present theory and suggests that only a fraction of V(mol)(dip) is involved at high x(IL). Expectedly, nice agreement between theory and experiments appears when

  14. Dielectric relaxation in ionic liquid/dipolar solvent binary mixtures: A semi-molecular theory

    NASA Astrophysics Data System (ADS)

    Daschakraborty, Snehasis; Biswas, Ranjit

    2016-03-01

    A semi-molecular theory is developed here for studying dielectric relaxation (DR) in binary mixtures of ionic liquids (ILs) with common dipolar solvents. Effects of ion translation on DR time scale, and those of ion rotation on conductivity relaxation time scale are explored. Two different models for the theoretical calculations have been considered: (i) separate medium approach, where molecularities of both the IL and dipolar solvent molecules are retained, and (ii) effective medium approach, where the added dipolar solvent molecules are assumed to combine with the dipolar ions of the IL, producing a fictitious effective medium characterized via effective dipole moment, density, and diameter. Semi-molecular expressions for the diffusive DR times have been derived which incorporates the effects of wavenumber dependent orientational static correlations, ion dynamic structure factors, and ion translation. Subsequently, the theory has been applied to the binary mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) with water (H2O), and acetonitrile (CH3CN) for which experimental DR data are available. On comparison, predicted DR time scales show close agreement with the measured DR times at low IL mole fractions (xIL). At higher IL concentrations (xIL > 0.05), the theory over-estimates the relaxation times and increasingly deviates from the measurements with xIL, deviation being the maximum for the neat IL by almost two orders of magnitude. The theory predicts negligible contributions to this deviation from the xIL dependent collective orientational static correlations. The drastic difference between DR time scales for IL/solvent mixtures from theory and experiments arises primarily due to the use of the actual molecular volume ( Vmol dip ) for the rotating dipolar moiety in the present theory and suggests that only a fraction of Vmol dip is involved at high xIL. Expectedly, nice agreement between theory and experiments appears when experimental

  15. Influence of solvent on ion aggregation and transport in PY15TFSI ionic liquid-aprotic solvent mixtures.

    PubMed

    Borodin, Oleg; Henderson, Wesley A; Fox, Eric T; Berman, Marc; Gobet, Mallory; Greenbaum, Steve

    2013-09-12

    Molecular dynamics (MD) simulations using a many-body polarizable APPLE&P force field have been performed on mixtures of the N-methyl-N-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PY15TFSI) ionic liquid (IL) with three molecular solvents: propylene carbonate (PC), dimethyl carbonate (DMC), and acetonitrile (AN). The MD simulations predict density, viscosity, and ionic conductivity values that agree well with the experimental results. In the solvent-rich regime, the ionic conductivity of the PY15TFSI-AN mixtures was found to be significantly higher than the conductivity of the corresponding -PC and -DMC mixtures, despite the similar viscosity values obtained from both the MD simulations and experiments for the -DMC and -AN mixtures. The significantly lower conductivity of the PY15TFSI-DMC mixtures, as compared to those for PY15TFSI-AN, in the solvent-rich regime was attributed to the more extensive ion aggregation observed for the -DMC mixtures. The PY15TFSI-DMC mixtures present an interesting case where the addition of the organic solvent to the IL results in an increase in the cation-anion correlations, in contrast to what is found for the mixtures with PC and AN, where ion motion became increasingly uncorrelated with addition of solvent. A combination of pfg-NMR and conductivity measurements confirmed the MD simulation predictions. Further insight into the molecular interactions and properties was also obtained using the MD simulations by examining the solvent distribution in the IL-solvent mixtures and the mixture excess properties.

  16. Surface and Interfacial Properties of Nonaqueous-Phase Liquid Mixtures Released to the Subsurface at the Hanford Site

    SciTech Connect

    Nellis, Scott; Yoon, Hongkyu; Werth, Charlie; Oostrom, Martinus; Valocchi, Albert J.

    2009-05-01

    Surface and interfacial tensions that arise at the interface between different phases are key parameters affecting Nonaqueous Phase Liquid (NAPL) movement and redistribution in the vadose zone after spill events. In this study, the impact of major additive components on surface and interfacial tensions for organic mixtures and wastewater was investigated. Organic mixture and wastewater compositions are based upon carbon tetrachloride (CT) mixtures released at the Hanford site, where CT was discharged simultaneously with dibutyl butyl phosphonate (DBBP), tributyl phosphate (TBP), dibutyl phosphate (DBP), and a machining lard oil (LO). A considerable amount of wastewater consisting primarily of nitrates and metal salts was also discharged. The tension values measured in this study revealed that the addition of these additive components caused a significant lowering of the interfacial tension with water or wastewater and the surface tension of the wastewater phase in equilibrium with the organic mixtures, compared to pure CT, but had minimal effect on the surface tension of the NAPL itself. These results lead to large differences in spreading coefficients for several mixtures, where the additives caused both a higher (more spreading) initial spreading coefficient and a lower (less spreading) equilibrium spreading coefficient. This indicates that if these mixtures migrate into uncontaminated areas, they will tend to spread quickly, but form a higher residual NAPL saturation after equilibrium, as compared to pure CT. Over time, CT likely volatilizes more rapidly than other components in the originally disposed mixtures and the lard oil and phosphates would become more concentrated in the remaining NAPL, resulting in a lower interfacial tension for the mixture. Spreading coefficients are expected to increase and perhaps change the equilibrated organic mixtures from nonspreading to spreading in water-wetting porous media. These results show that the behavior of organic

  17. Thermal and optical characterization of liquid crystal 4‧-hexyl-4-biphenylcarbonitrile/4-hexylbenzoic acid mixtures

    NASA Astrophysics Data System (ADS)

    Okumuş, Mustafa; Özgan, Şükrü; Kırık, İhsan; Kerli, Süleyman

    2016-09-01

    We present the thermal and optical properties of binary mixtures formed from hydrogen-bonded liquid crystal 4-hexylbenzoic acid (6BA) and 4-hexyl-4‧-biphenylcarbonitrile (6CB) mesogens. Phase transition temperatures and enthalpy values are evaluated by differential scanning calorimetry (DSC) and phases identified by polarized optic microscopy (POM). The experimental results obviously show that the 6BA/6CB binary mixtures exhibit nematic and smectic phases. The most interesting result is that although the smectic phase is not observed in pure components 6BA and 6CB, it is observed in their some binary mixtures. The thermal properties like phase peak temperatures, enthalpy changes and thermal span of binary mixtures are affected by depending on the mixture ratio. The nematic range increase in the binary mixture compared to the individual mesogen, and also the phase transition temperature values and the nematic thermal stability factor increase as heating rate increases. Furthermore, the calculated activation energy values show that the reorientation of the molecules during the phase transitions of the mixture occurs on an orderly basis.

  18. Unusual solvatochromic absorbance probe behaviour within mixtures of poly(ethylene glycol)-400 + ionic liquid, [bmim][Tf2N

    NASA Astrophysics Data System (ADS)

    Ali, Anwar; Ali, Maroof; Malik, Nisar Ahmad; Uzair, Sahar

    2014-03-01

    The potentially green solvents made up of ionic liquids (ILs) and poly(ethylene glycols) may have wide range of the applications in many chemical and biochemical fields. In the present work, solvatochromic absorbance probe behaviour is used to assess the physicochemical properties of the mixtures composed of PEG-400 + IL, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][Tf2N]. Lowest energy intramolecular charge-transfer absorbance maxima of a betaine dye, i.e., ETN , indicates the dipolarity/polarizability and/or hydrogen-bond donating (HBD) acidity of the [bmim][Tf2N] + PEG-400 mixtures to be even higher than that of neat [bmim][Tf2N], the solution component with higher dipolarity/polarizability and/or HBD acidity. Dipolarity/polarizability (π∗) obtained separately from the electronic absorbance response of probe N,N-diethyl-4-nitroaniline, and the HBD acidity (α) of PEG-400 + [bmim][Tf2N] mixtures are also observed to be anomalously high. A comparative study of the PEG + IL mixtures has also been done with PEG-400 + molecular organic solvents (protic polar [methanol], aprotic polar [N,N-dimethylformamide], and non polar, [benzene]) mixtures, but these mixtures do not show this type of unusual behaviour. A four-parameter simplified combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation is shown to satisfactorily predict the solvatochromic parameters within PEG-400 + different solvent mixtures.

  19. Modeling and dynamic properties of dual-chamber solid and liquid mixture vibration isolator

    NASA Astrophysics Data System (ADS)

    Li, F. S.; Chen, Q.; Zhou, J. H.

    2016-07-01

    The dual-chamber solid and liquid mixture (SALiM) vibration isolator, mainly proposed for vibration isolation of heavy machines with low frequency, consists of four principle parts: SALiM working media including elastic elements and incompressible oil, multi-layers bellows container, rigid reservoir and the oil tube connecting the two vessels. The isolation system under study is governed by a two-degrees-of-freedom (2-DOF) nonlinear equation including quadratic damping. Simplifying the nonlinear damping into viscous damping, the equivalent stiffness and damping model is derived from the equation for the response amplitude. Theoretical analysis and numerical simulation reveal that the isolator's stiffness and damping have multiple properties with different parameters, among which the effects of exciting frequency, vibrating amplitude, quadratic damping coefficient and equivalent stiffness of the two chambers on the isolator's dynamics are discussed in depth. Based on the boundary characteristics of stiffness and damping and the main causes for stiffness hardening effect, improvement strategies are proposed to obtain better dynamic properties. At last, experiments were implemented and the test results were generally consistent with the theoretical ones, which verified the reliability of the nonlinear dynamic model.

  20. DETERMINATION OF SOLID-LIQUID EQUILIBRIA DATA FOR MIXTURES OF HEAVY HYDROCARBONS IN A LIGHT SOLVENT

    SciTech Connect

    F.V. Hanson; J.V. Fletcher; Karthik R.

    2003-06-01

    A methodology was developed using an FT-IR spectroscopic technique to obtain solid-liquid equilibria (SLE) data for mixtures of heavy hydrocarbons in significantly lighter hydrocarbon diluents. SLE was examined in multiple Model Oils that were assembled to simulate waxes. The various Model oils were comprised of C-30 to C-44 hydrocarbons in decane. The FT-IR technique was used to identify the wax precipitation temperature (WPT). The DSC technique was also used in the identification of the onset of the two-phase equilibrium in this work. An additional Model oil made up of C-20 to C-30 hydrocarbons in decane was studied using the DSC experiment. The weight percent solid below the WPT was calculated using the FT-IR experimental results. The WPT and the weight percent solid below the WPT were predicted using an activity coefficient based thermodynamic model. The FT-IR spectroscopy method is found to successfully provide SLE data and also has several advantages over other laboratory-based methods.

  1. Phase conversion and interface growth in phase-separated 3He - 4He liquid mixtures

    NASA Astrophysics Data System (ADS)

    Abe, Haruka; Satoh, Takeo; Burmistrov, Serguei N.

    2005-10-01

    We have developed a method for measuring the transmission coefficient of a sound propagating through the interface in phase-separated He3-He4 liquid mixtures. The method and the results are described with discussions by examining the phase-conversion process of He3 quasiparticles driven to flow across the interface. From the data, we have determined the kinetic growth coefficient of the interface, ξ(T,P,ω) , as a function of temperature, pressure, and frequency. The temperature range of the present investigation is about 2-100mK at the pressure mainly around 1bar with sound frequency 9.64, 14.4, and 32.4MHz . The main specific features observed for the kinetic growth coefficient are, as follows: (i) there is a maximum at some temperature Tm(ω) depending on the frequency, (ii) above Tm(ω) , ξ decreases with the increase of temperature as ∝ω5/2T-3 , and (iii) below Tm(ω) , ξ becomes frequency independent and diminishes as a cube of temperature, T3 .

  2. A Method for Microscale Combustion of Near Stoichiometric Energy Dense Liquid Fuel Mixtures

    NASA Astrophysics Data System (ADS)

    Tolmachoff, E. D.; Allmon, W. R.; Waits, C. M.

    2013-12-01

    This paper reports on the potential of a heterogeneous/homogeneous (HH) reactor for use as a fuel-flexible heat source, meeting the needs of the next generation of high temperature thermal-to-electric (TEC) portable power converters. In this class of reactor, low activation energy catalytic reactions provide a means to stabilize high activation energy homogeneous reactions. Diffusion limited surface reactions play a critical role in HH reactor operation. Surface conversion must be sufficiently fast to generate the high temperatures (~1000 K) necessary to initiate gas phase reactions. Therefore, fuel diffusivity and the reactor dimension are important parameters in governing HH reactor operation. We examine the performance of an HH reactor fuelled by propane and n-dodecane, representing two extremes of liquid hydrocarbon diffusivity, as a function of confining reactor dimension. Unburned fuel/air mixtures are close to stoichiometric, which is an important factor in minimizing the amount of excess air and, therefore, balance of plant energy costs. At moderate levels of confinement, the reactor is capable producing high, uniform temperatures for both fuels.

  3. Method of extracting iodine from liquid mixtures of iodine, water and hydrogen iodide

    DOEpatents

    Mysels, Karol J.

    1979-01-01

    The components of a liquid mixture consisting essentially of HI, water and at least about 50 w/o iodine are separated in a countercurrent extraction zone by treating with phosphoric acid containing at least about 90 w/o H.sub.3 PO.sub.4. The bottom stream from the extraction zone is substantially completely molten iodine, and the overhead stream contains water, HI, H.sub.3 PO.sub.4 and a small fraction of the amount of original iodine. When the water and HI are present in near-azeotropic proportions, there is particular advantage in feeding the overhead stream to an extractive distillation zone wherein it is treated with additional concentrated phosphoric acid to create an anhydrous HI vapor stream and bottoms which contain at least about 85 w/o H.sub.3 PO.sub.4. Concentration of these bottoms provides phosphoric acid infeed for both the countercurrent extraction zone and for the extractive distillation zone.

  4. Studies on the tosylation of cellulose in mixtures of ionic liquids and a co-solvent.

    PubMed

    Gericke, Martin; Schaller, Jens; Liebert, Tim; Fardim, Pedro; Meister, Frank; Heinze, Thomas

    2012-06-20

    The tosylation of cellulose in ionic liquids (ILs) was studied. Due to the beneficial effect of different co-solvents, the reaction could be performed at 25°C without the need of heating (in order to reduce viscosity) or cooling (in order to prevent side reactions). The effects of reaction parameters, such as time, molar ratio, and type of base, on the degree of substitution (DS) with tosyl- and chloro-deoxy groups as well as on the molecular weight were evaluated. Products with a DStosyl≤1.14 and DSCl≤0.16 were obtained and characterized by means of NMR- and FT-IR spectroscopy in order to evaluate their purity and distribution of functional groups within the modified anhydroglucose unit (AGU). Tosylation of cellulose in mixtures of IL and a co-solvent was found to result in predominant substitution at the primary hydroxyl group. Size exclusion chromatography (SEC) revealed only a moderate degradation of the polymer backbone at a reaction time of 4-8h. Finally, the nucleophilic displacement (SN) of tosyl- and chloro-deoxy groups by azide as well as recycling of the ILs was studied. PMID:24750754

  5. Morphology and Ionic Conductivity of Oriented Block Copolymer/Ionic Liquid Mixtures

    NASA Astrophysics Data System (ADS)

    Sharick, Sharon; Winey, Karen I.

    2015-03-01

    Ion-containing block copolymers with increased continuity and long-range order of ion-containing microdomains were prepared to probe the impact of grain boundaries and microdomain orientation on ion transport. We studied poly(styrene- b-methyl methacrylate) diblock copolymers swollen with 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonylimide) (SbMMA/IL), and characterized the thermal transitions, morphologies, and ionic conductivities by differential scanning calorimetry, small-angle X-ray scattering, and electrochemical impedance spectroscopy over a range of compositions. Two glass transition temperatures (Tgs) are observed, corresponding to PS and PMMA/IL microdomains, and Tg,PMMA/IL is modeled well by the Gordon-Taylor expression. SbMMA/IL films prepared by solvent evaporation exhibit strongly microphase-separated lamellar morphology with long-range order. Slower rates of solvent evaporation produce films with lamellae preferentially oriented to be in the plane. In-plane conductivities increase with both increasing ionic liquid content and with better parallel alignment of lamellae. The Sax and Ottino model will be used to compare the conductivity of SbMMA/IL with the homopolymer/IL mixture, PMMA/IL, and to discuss the ion transport mechanism.

  6. Nonvolatile memory effects in an orthoconic smectic liquid crystal mixture doped with polymer-capped gold nanoparticles.

    PubMed

    Marino, L; Marino, S; Wang, D; Bruno, E; Scaramuzza, N

    2014-06-01

    Promising applications of liquid crystal nanocomposites have driven extensive efforts to achieve non-volatile memory effects for the realization of electronic storage devices. In this context, non-volatile memory effects in an orthoconic smectic liquid crystal mixture, with and without polymer capped gold nanoparticles, were investigated. The dielectric spectroscopy technique was performed by applying a d.c. bias during the measurement or a d.c. potential before the start of the measurement in order to obtain pre-conditioning of the sample. Both techniques showed the presence of non-volatile memory effects in the pure orthoconic smectic liquid crystal mixture similar to the doped one. The results demonstrate that the addition of gold nanoparticles enhances the memory effect making it permanent. Our experimental evidence underlines the importance of the structure of the host liquid crystal and clearly suggests that the prolonged time memory effect, observed in the doped liquid crystal, is due to the electric field inducing charge transfer from the liquid crystal molecules to the gold nanoparticles, thanks to the polymer-capping which acts as an ionic charge trapper. Such an ionic trap effect is also responsible for strong reduction of total conductivity of the doped system.

  7. Effects of variation in chain length on ternary polymer electrolyte - Ionic liquid mixture - A molecular dynamics simulation study

    NASA Astrophysics Data System (ADS)

    Raju, S. G.; Hariharan, Krishnan S.; Park, Da-Hye; Kang, HyoRang; Kolake, Subramanya Mayya

    2015-10-01

    Molecular dynamics (MD) simulations of ternary polymer electrolyte - ionic liquid mixtures are conducted using an all-atom model. N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([CnMPy][TFSI], n = 1, 3, 6, 9) and polyethylene oxide (PEO) are used. Microscopic structure, energetics and dynamics of ionic liquid (IL) in these ternary mixtures are studied. Properties of these four pure IL are also calculated and compared to that in ternary mixtures. Interaction between pyrrolidinium cation and TFSI is stronger and there is larger propensity of ion-pair formation in ternary mixtures. Unlike the case in imidazolium IL, near neighbor structural correlation between TFSI reduces with increase in chain length on cation in both pure IL and ternary mixtures. Using spatial density maps, regions where PEO and TFSI interact with pyrrolidinium cation are identified. Oxygens of PEO are above and below the pyrrolidinium ring and away from the bulky alkyl groups whereas TFSI is present close to nitrogen atom of CnMPy. In pure IL, diffusion coefficient (D) of C3MPy is larger than of TFSI but D of C9MPy and C6MPy are larger than that of TFSI. The reasons for alkyl chain dependent phenomena are explored.

  8. The Amphiphilic Character of Cellulose Molecules in True Solution in Solvent Mixtures Containing Ionic Liquid and its Utilization in Emulsification

    NASA Astrophysics Data System (ADS)

    Napso, Sofia; Cohen, Yachin; Rein, Dmitry; Khalfin, Rafail; Szekely, Noemi

    2015-03-01

    Cellulose is the most abundant renewable material in nature that is utilized as a raw material for fabrication of synthetic products. Although it is not soluble in common solvents, there is significant interest in the use of solvent mixtures containing ionic liquids (IL) and polar organic solvents for cellulose dissolution. We present evidence for true molecular dissolution of cellulose in binary mixtures of common polar organic solvents with an ionic liquid, using cryogenic transmission electron microscopy, small-angle neutron-, x-ray- and static light scattering. In particular, the measured low values of the molecular, gyration radius and persistence length indicate the absence of significant aggregation of the dissolved chains. We conjecture that the dissolved cellulose chains are amphiphilic. This can be inferred from the facile fabrication of cellulose-encapsulated colloidal oil-in-water or water-in-oil dispersions. This may be done by mixing water, oil and cellulose solution in an ionic liquid. A more practical alternative is to form first a hydrogel from the cellulose/ionic liquid solution by coagulation with water and applying it to sonicated water/oil or oil/water mixtures. Apparently the dissolution/ regeneration process affords higher mobility to the cellulose molecules so an encapsulation coating can be formed at the water-oil interface.

  9. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: Rotational viscosity of a liquid crystal mixture: a fully atomistic molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Zhang, Ran; Peng, Zeng-Hui; Liu, Yong-Gang; Zheng, Zhi-Gang; Xuan, Li

    2009-10-01

    Fully atomistic molecular dynamics (MD) simulations at 293, 303 and 313 K have been performed for the four-component liquid crystal mixture, E7, using the software package Material Studio. Order parameters and orientational time correlation functions (TCFs) were calculated from MD trajectories. The rotational viscosity coefficients (RVCs) of the mixture were calculated using the Nemtsov-Zakharov and Fialkowski methods based on statistical-mechanical approaches. Temperature dependences of RVC and density were discussed in detail. Reasonable agreement between the simulated and experimental values was found.

  10. Bubble pressures and saturated liquid densities of R 22 + R 114 mixtures in the range 310 400 K

    NASA Astrophysics Data System (ADS)

    Fukuizumi, H.; Uematsu, M.

    1991-03-01

    The bubble pressures and saturated liquid densities of mixtures of R 22 and R 114 have been measured with a static and synthetic method with a variable-volume cell. The results for five different compositions (100, 75, 50, 25, and 0 mol% R 22) cover the temperature range from 310 to 400 K. The experimental data for both pure components are compared with literature data, showing the reliability of the present results. The system shows positive deviations from Raoult's law at temperatures below 340 K and the deviations increase with decreasing temperature. The 25 mol % R 22 mixture shows the maximum non-ideality.

  11. A theoretical and experimental chemist's joint view on hydrogen bonding in ionic liquids and their binary mixtures.

    PubMed

    Stark, Annegret; Brehm, Martin; Brüssel, Marc; Lehmann, Sebastian B C; Pensado, Alfonso S; Schöppke, Matthias; Kirchner, Barbara

    2014-01-01

    A combined experimental and theoretical approach including quantum chemistry tools and computational simulation techniques can provide a holistic description of the nature of the interactions present in ionic liquid media. The nature of hydrogen bonding in ionic liquids is an especially intriguing aspect, and it is affected by all types of interactions occurring in this media. Overall, these interactions represent a delicate balance of forces that influence the structure and dynamics, and hence the properties of ionic liquids. An understanding of the fundamental principles can be achieved only by a combination of computations and experimental work. In this contribution we show recent results shedding light on the nature of hydrogen bonding, for certain cases the formation of a three-dimensional network of hydrogen bonding, and its dynamics by comparing 1-ethyl-3-methylimidazolium based acetate, chloride and thiocyanate ionic liquids.A particularly interesting case to study hydrogen bonding and other interactions is the investigation of binary mixtures of ionic liquids of the type [cation1][anion1]/[cation1][anion2]. In these mixtures, competing interactions are to be expected. We present both a thorough property meta-analysis of the literature and new data covering a wide range of anions, i.e., mixtures of 1-ethyl-3-methylimidazolium acetate with either trifluoroacetate, tetrafluoroborate, methanesulfonate, or bis(trifluoromethanesulfonyl)imide. In most cases, ideal mixing behavior is found, a surprising result considering the multitude of interactions present. However, ideal mixing behavior allows for the prediction of properties such as density, refractive index, surface tension, and, in most cases, viscosity as function of molar composition. Furthermore, we show that the prediction of properties such as the density of binary ionic liquid mixtures is possible by making use of group contribution methods which were originally developed for less complex non

  12. New methods for determination of cinnarizine in mixture with piracetam by spectrodensitometry, spectrophotometry, and liquid chromatography.

    PubMed

    Metwally, Fadia H; Elzeany, B A; Darwish, H W

    2005-01-01

    Four new methods were developed and validated for the determination of cinnarizine HCl in its binary mixture with piracetam in pure and pharmaceutical preparations. The first one was a densitometric analysis that provides a simple and rapid method for the separation and quantification of cinnarizine HCI. The method depends on the quantitative densitometric evaluation of thin-layer chromatograms of cinnarizine HCI at 252 nm over concentration range of 1-6 microg/spot, with a mean accuracy of 100.05 +/- 0.91%. The second method was determination of the drug using a colorimetric method that utilizes the reaction of 3-methyl-benzothiazolin-2-one in the presence of FeCl3 as an oxidant. The green color of the resulting product was measured at 630 nm over concentration range 10-40 microg/mL, with a mean accuracy of 100.10 +/- 1.13%. The third method was a direct spectrophotometric determination of cinnarizine HCI at 252 nm over the concentration range 7-20 microg/mL, while piracetam was determined by derivative ratio spectrophotometry at 221.6 nm over concentration range 5-30 microg/mL, with a mean accuracy of 100.14 +/- 0.79 and 100.26 +/- 1.24% for cinnarizine HCI and piracetam, respectively. The last method was a liquid chromatography analysis of both cinnarizine HCI and piracetam, depending on quantitative evaluation of chromatograms of cinnarizine HCI and piracetam at 252 and 212 nm, respectively, over the concentration range 10-200 microg/mL for cinnarizine HCI and 20-500 microg/mL for piracetam, with a mean accuracy of 100.03 +/- 0.89 and 100.40 +/- 0.94% for cinnarizine HCI and piracetam, respectively. The proposed procedures were checked using laboratory-prepared mixtures and successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed procedures was further assessed by applying the standard addition technique. Recoveries were quantitative, and the results obtained agreed with those obtained by other reported methods

  13. Study on optical characterization of TGB and reentrant smectic-A phases in binary mixture of two liquid crystals

    NASA Astrophysics Data System (ADS)

    Govindaiah, T. N.; Sreepad, H. R.

    2015-04-01

    In this work, our investigation is to study the optical and thermal properties of the binary mixture of cholesteric and nematic compounds, namely, cholesteryl nonanoate and p-methoxybenzylidene-p-ethylaniline, which exhibits a very interesting liquid crystalline twisted grain boundary (TGB) phase and reentrant smectic-A phase. The chiral liquid crystalline TGB phases and reentrant smectic-A phases have been observed at different concentrations and at different temperatures. The existence of TGB and reentrant smectic-A phases is confirmed by differential scanning calorimetry and optical microscopic studies. The variation of optical anisotropy has been discussed. The helical pitch of the cholesteric phase has also been discussed.

  14. The importance of multiphase and multicomponent modeling in consequence and risk analysis.

    PubMed

    Johnson, David W; Marx, Jeffrey D

    2003-11-14

    The ability to accurately predict the consequences of hazardous fluid release is dependent on three things: the knowledge of the modeler, the quality of the model that is used, and the quality of the input parameters. One of the most difficult problems in consequence modeling is the prediction of post-release multiphase behavior, especially when a multicomponent mixture is involved. Releases from gas/oil wells often fit this description. The wellstream will produce a light crude oil and a gas stream when flashed into a separator. If accidentally released to the atmosphere, the gas, aerosol, and liquid fractions rarely match the phase separations in the separator, or the expectations of the modeler. And, since the wellstream has a wide range of hydrocarbon components, the need to accurately predict the multicomponent behavior becomes more important. Over the years, modelers have used several "rules of thumb" to provide the source term input parameters for modeling multiphase/multicomponent releases and subsequent dispersion. These modeling assumptions can lead to hazard predictions that are very different from reality. The biggest problem with rules of thumb is their inability to account for thermodynamics; thus, they cannot approximate the phase splits and composition changes that do occur. The aim of this paper is to improve the knowledge of the modeler by providing some insight into the selection of the proper input parameters for multiphase releases of multicomponent fluids. The application of a multiphase release model with multicomponent thermodynamics to a wellstream release is used to illustrate the importance of good modeling techniques.

  15. Atomistic Insight into Tetraalkylphosphonium-Bis(oxalato)borate Ionic Liquid/Water Mixtures. I. Local Microscopic Structure.

    PubMed

    Wang, Yong-Lei; Sarman, Sten; Glavatskih, Sergei; Antzutkin, Oleg N; Rutland, Mark W; Laaksonen, Aatto

    2015-04-23

    Atomistic simulations have been performed to investigate the microscopic structural organization of aqueous solutions of trihexyltetradecylphosphonium bis(oxalato)borate ([P6,6,6,14][BOB]) ionic liquid (IL). The evolution of the microscopic liquid structure and the local ionic organization of IL/water mixtures as a function of the water concentration is visualized and systematically analyzed via radial and spatial distribution functions, coordination numbers, hydrogen bond network, and water clustering analysis. The microscopic liquid structure in neat IL is characterized by a connected apolar network composed of the alkyl chains of [P6,6,6,14] cations and isolated polar domains consisting of the central segments of [P6,6,6,14] cations and [BOB] anions, and the corresponding local ionic environment is described by direct contact ion pairs. In IL/water mixtures with lower water mole fractions, the added water molecules are dispersed and embedded in cavities between neighboring ionic species and the local ionic structure is characterized by solvent-shared ion pairs through cation-water-anion triple complexes. With a gradual increase in the water concentration in IL/water mixtures, the added water molecules tend to aggregate and form small clusters, intermediate chain-like structures, large aggregates, and eventually a water network in water concentrated simulation systems. A further progressive dilution of IL/water mixtures leads to the formation of self-organized micelle-like aggregates characterized by a hydrophobic core and hydrophilic shell consisting of the central polar segments in [P6,6,6,14] cations and [BOB] anions in a highly branched water network. The striking structural evolution of the [P6,6,6,14][BOB] IL/water mixtures is rationalized by the competition between favorable hydrogen bonded interactions and strong electrostatic interactions between the polar segments in ionic species and the dispersion interactions between the hydrophobic alkyl chains in

  16. Cellulose amorphization by swelling in ionic liquid/water mixtures: a combined macroscopic and second-harmonic microscopy study.

    PubMed

    Glas, Daan; Paesen, Rik; Depuydt, Daphne; Binnemans, Koen; Ameloot, Marcel; De Vos, Dirk E; Ameloot, Rob

    2015-01-01

    Amorphization of cellulose by swelling in ionic liquid (IL)/water mixtures at room temperature is a suitable alternative to the dissolution-precipitation pretreatment known to facilitate enzymatic digestion. When soaking microcrystalline cellulose in the IL 1-ethyl-3-methylimidazolium acetate containing 20 wt % water, the crystallinity of the cellulose sample is strongly reduced. As less than 4 % of the cellulose dissolves in this mixture, this swelling method makes a precipitation step and subsequent energy-intensive IL purification redundant. Second-harmonic generation (SHG) microscopy is used as a structure-sensitive technique for in situ monitoring of the changes in cellulose crystallinity. Combined optical and SHG observations confirm that in the pure IL complete dissolution takes place, while swelling without dissolution in the optimal IL/water mixture yields a solid cellulose with a significantly reduced crystallinity in a single step. PMID:25363520

  17. Molecular dynamics of a binary mixture of twist-bend nematic liquid crystal dimers studied by dielectric spectroscopy

    NASA Astrophysics Data System (ADS)

    Robles-Hernández, Beatriz; Sebastián, Nerea; Salud, Josep; Diez-Berart, Sergio; Dunmur, David A.; Luckhurst, Geoffrey R.; López, David O.; de la Fuente, M. Rosario

    2016-06-01

    We report a comprehensive dielectric characterization of a liquid crystalline binary mixture composed of the symmetric mesogenic dimer CB7CB and the nonsymmetric mesogenic dimer FFO9OCB. In addition to the high-temperature nematic phase, such a binary mixture shows a twist-bend nematic phase at room temperature which readily vitrifies on slow cooling. Changes in the conformational distribution of the dimers are reflected in the dielectric permittivity and successfully analyzed by means of an appropriate theoretical model. It is shown that the dielectric spectra of the mixture reflect the different molecular dipole properties of the components, resembling in the present case the characteristic dielectric spectra of nonsymmetric dimers. Comparison of the nematic and twist-bend nematic phases reveals that molecular dynamics are similar despite the difference in the molecular environment.

  18. Wide range room temperature electroclinic liquid crystal mixture with large induced tilt and very small layer contraction

    NASA Astrophysics Data System (ADS)

    Debnath, Asim; Sinha, Debashis; Mandal, Pradip Kumar

    2016-03-01

    Optical polarizing microscopy, synchrotron X-ray scattering, and electro-optic studies in the SmA* phase of a formulated wide range room temperature liquid crystal mixture indicate a large electric field induced optical tilt up to 23.5° along with a very small contraction of smectic layers. Applied field primarily lifts the zero-field degeneracy of the azimuthal order of the molecules in smectic layers resulting in small layer contraction.

  19. Influence of the ionic liquid cation on the solvent extraction of trivalent rare-earth ions by mixtures of Cyanex 923 and ionic liquids.

    PubMed

    Rout, Alok; Binnemans, Koen

    2015-01-21

    Trivalent rare-earth ions were extracted from nitric acid medium by the neutral phosphine oxide extractant Cyanex 923 into ionic liquid phases containing the bis(trifluoromethylsulfonyl)imide anion. Five different cations were considered: 1-butyl-3-methylimidazolium, 1-decyl-3-methylimidazolium, methyltributylammonium, methyltrioctylammonium and trihexyl(tetradecyl)phosphonium. The extraction behavior of neodymium(iii) was investigated as a function of various parameters: pH, extractant concentration, concentration of the neodymium(iii) ion in the aqueous feed and concentration of the salting-out agent. The loading capacity of the ionic liquid phase was studied. The extraction efficiency increased with increasing pH of the aqueous feed solution. The extraction occurred for all ionic liquids via an ion-exchange mechanism and the extraction efficiency could be related to the solubility of the ionic liquid cation in the aqueous phase: high distribution ratios for hydrophilic cations and low ones for hydrophobic cations. Addition of nitrate ions to the aqueous phase resulted in an increase in extraction efficiency for ionic liquids with hydrophobic cations due to extraction of neutral complexes. Neodymium(iii) could be stripped from the ionic liquid phase by 0.5-1.0 M nitric acid solutions and the extracting phase could be reused. The extractability of other rare earths present in the mixture was compared for the five ionic liquids.

  20. Atomistic simulations of liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2PhP and PhP14.

    PubMed

    Yan, Fangyong; Earl, David J

    2012-03-28

    We study liquid crystal mixtures of alkoxy substituted phenylpyrimidines 2-[4-(butyloxy)phenyl]-5-(octyloxy)pyrimidine (2PhP) and 2-[4-(tetradecyloxy)phenyl]-5-(tetradecyloxy)pyrimidine (PhP14) using molecular dynamics simulations at the all atom level. The molecular length of PhP14 is 1.8 times that of 2PhP, resulting in an interesting binary mixture phase diagram. Our simulations are composed of 1000-1600 molecules for a total of 80,000-130,000 atomic sites, with total simulation times of 60-100 ns. We first show that a pure 2PhP system self-assembles into isotropic, nematic, smectic A and smectic C phases, and a pure PhP14 system self-assembles into isotropic and smectic C phases. Binary mixtures of PhP14 and 2PhP display a stabilization of the smectic A phase at the expense of the smectic C and nematic phases. We determine that the concentration-induced phase transition from the smectic C to the smectic A phase in the mixture is driven by an out-of-layer fluctuation arrangement of the molecules. We also observe that the tilt angle in the smectic C phases formed in the mixtures is concentration dependent. The results of our simulations are in good agreement with the experimental findings of Kapernaum et al. [J. Org. Chem. 5, 65 (2009)], thus showing that atomistic simulations are capable of reproducing the phase behavior of liquid crystal mixtures and can also provide microscopic details regarding the mechanisms that govern phase stability.

  1. Phase behaviors of binary mixtures composed of electron-rich and electron-poor triphenylene discotic liquid crystals

    NASA Astrophysics Data System (ADS)

    An, Lingling; Jing, Min; Xiao, Bo; Bai, Xiao-Yan; Zeng, Qing-Dao; Zhao, Ke-Qing

    2016-09-01

    Disk-like liquid crystals (DLCs) can self-assemble to ordered columnar mesophases and are intriguing one-dimensional organic semiconductors with high charge carrier mobility. To improve their applicable property of mesomorphic temperature ranges, we exploit the binary mixtures of electronic donor-acceptor DLC materials. The electron-rich 2,3,6,7,10,11-hexakis(alkoxy)triphenylenes (C4, C6, C8, C10, C12) and an electron-deficient tetrapentyl triphenylene-2,3,6,10-tetracarboxylate have been prepared and their binary mixtures have been investigated. The mesomorphism of the 1:1 (molar ratio) mixtures has been characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and small angel x-ray scattering (SAXS). The self-assembled monolayer structure of a discogen on a solid-liquid interface has been imaged by the high resolution scanning tunneling microscopy (STM). The match of peripheral chain length has important influence on the mesomorphism of the binary mixtures. Project supported by the National Natural Science Foundation of China (Grant Nos. 51273133 and 51443004).

  2. Analysis of gas centrifuge cascade for separation of multicomponent isotopes and optimal feed position

    SciTech Connect

    Chuntong Ying; Hongjiang Wu; Mingsheng Zhou; Yuguang Nie; Guangjun Liu

    1997-10-01

    Analysis of the concentration distribution in a gas centrifuge cascade for separation of multicomponent isotope mixtures is different from that in a cascade for separation of two-component mixtures. This paper presents the governing equations for a multicomponent isotope separation cascade. Numerically predicted separation factors for the gas centrifuge cascade agree well with the experimental data. A theoretical optimal feed position is derived for a short square cascade for a two-component mixture in a close-separation case. The optimal feed position for a gas centrifuge cascade for separation of multicomponent mixture is discussed.

  3. Second-Order Derivatives of the Gibbs Energy for Liquid Mixtures of Alcohol + Heptane at Pressures up to 100 MPa

    NASA Astrophysics Data System (ADS)

    Dzida, Marzena; Kaczmarczyk, Aleksandra

    2012-04-01

    Second-order thermodynamic derivative properties, such as isobaric thermal molar expansions, isothermal and adiabatic molar compressibilities, and isochoric molar heat capacities of (ethanol, decan-1-ol, 2-methyl-2-butanol) + heptane mixtures at pressures up to 100 MPa and in the temperature range from 293.15 K to 318.15 K were derived from experimental speed-of-sound u( T, p), density ρ( T, p = 0.1 MPa), and isobaric heat-capacity C p ( T, p = 0.1 MPa) data using appropriate thermodynamic relations. Excess values for the given properties were calculated according to the criterion of thermodynamic ideality of a mixture (Douhéret et al., Chem. Phys. Chem. 2, 148 (2001)), i.e., assuming that the chemical potential of component i in the ideal liquid mixture is equal to the chemical potential of component i in the mixture of perfect gases. The deviations from ideality for the mixtures under test have been explained in terms of the self-association of alcohols in solution which produces a strong departure from random mixing, the change in the non-specific interactions during mixing, and the packing effects.

  4. Vapor-Liquid Equilibrium in the Mixture 1-Chlorobutane C4H9Cl + C6H10O Cyclohexanone (EVLM1111, LB5637_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture 1-Chlorobutane C4H9Cl + C6H10O Cyclohexanone (EVLM1111, LB5637_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

  5. Vapor-Liquid Equilibrium in the Mixture 1,2-Dichloroethane C2H4Cl2 + C6H10O Cyclohexanone (EVLM1111, LB5653_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture 1,2-Dichloroethane C2H4Cl2 + C6H10O Cyclohexanone (EVLM1111, LB5653_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

  6. Vapor-Liquid Equilibrium in the Mixture Cyclohexanone C6H10O + C6H12O Cyclohexanol (EVLM1111, LB5657_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture Cyclohexanone C6H10O + C6H12O Cyclohexanol (EVLM1111, LB5657_E)' providing data from direct measurement of pressure at variable mole fraction in liquid phase and constant temperature.

  7. Vapor-Liquid Equilibrium in the Mixture Chlorodifluoromethane CHClF2 + C2ClF5 Chloropentafluoroethane (EVLM1311, LB5621_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture Chlorodifluoromethane CHClF2 + C2ClF5 Chloropentafluoroethane (EVLM1311, LB5621_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

  8. Vapor-Liquid Equilibrium in the Mixture 1,2-Dichloroethane C2H4Cl2 + C3H3N Propenenitrile (EVLM1211, LB5647_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture 1,2-Dichloroethane C2H4Cl2 + C3H3N Propenenitrile (EVLM1211, LB5647_E)' providing data from direct measurement of temperature at variable mole fraction in liquid phase and constant pressure.

  9. Vapor-Liquid Equilibrium in the Mixture Propenenitrile C3H3N + C6H5Cl Chlorobenzene (EVLM1211, LB5649_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture Propenenitrile C3H3N + C6H5Cl Chlorobenzene (EVLM1211, LB5649_E)' providing data from direct measurement of temperature at variable mole fraction in liquid phase and constant pressure.

  10. Vapor-Liquid Equilibrium in the Mixture Propenenitrile C3H3N + C6H5NO2 Nitrobenzene (EVLM1211, LB5650_E)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture Propenenitrile C3H3N + C6H5NO2 Nitrobenzene (EVLM1211, LB5650_E)' providing data from direct measurement of temperature at variable mole fraction in liquid phase and constant pressure.

  11. Ignition delay of a gas mixture above a liquid fuel pool

    NASA Technical Reports Server (NTRS)

    Schiller, D. N.; Sirignano, W. A.

    1991-01-01

    A computational study has been made of transient heat transfer and fluid flow of an axisymmetric two-layer gas-and-liquid system heated from above by a small hot spot (e.g., a hot wire or pilot flame) located close to the liquid surface. The gas phase is unconfined above the liquid pool. The effects of varying gravity level (0.0001 to 1 gn), liquid pool height, and heater height are investigated. Thermocapillary convection induced by the nonuniform heating of the liquid surface combines with buoyancy forces to affect the heat transfer and the transport of fuel vapor toward the heat source. At reduced gravity, gas-phase conduction is comparable to the incident radiation at the liquid surface, whereas at 1 gn, buoyant convection carries the heat upward from the heat source and, therefore, the liquid is heated primarily by radiation.

  12. Flow pattern changes influenced by variation of viscosities of a heterogeneous gas-liquid mixture flow in a vertical channel

    SciTech Connect

    Keska, Jerry K.; Hincapie, Juan; Jones, Richard

    2011-02-15

    In the steady-state flow of a heterogeneous mixture such as an air-liquid mixture, the velocity and void fraction are space- and time-dependent parameters. These parameters are the most fundamental in the analysis and description of a multiphase flow. The determination of flow patterns in an objective way is extremely critical, since this is directly related to sudden changes in spatial and temporal changes of the random like characteristic of concentration. Flow patterns can be described by concentration signals in time, amplitude, and frequency domains. Despite the vital importance and countless attempts to solve or incorporate the flow pattern phenomena into multiphase models, it has still been a very challenging topic in the scientific community since the 1940's and has not yet reached a satisfactory solution. This paper reports the experimental results of the impact of fluid viscosity on flow patterns for two-phase flow. Two-phase flow was created in laboratory equipment using air and liquid as phase medium. The liquid properties were changed by using variable concentrations of glycerol in water mixture which generated a wide-range of dynamic viscosities ranging from 1 to 1060 MPa s. The in situ spatial concentration vs. liquid viscosity and airflow velocity of two-phase flow in a vertical ID=50.8 mm pipe were measured using two concomitant computer-aided measurement systems. After acquiring data, the in situ special concentration signals were analyzed in time (spatial concentration and RMS of spatial concentration vs. time), amplitude (PDF and CPDF), and frequency (PSD and CPSD) domains that documented broad flow pattern changes caused by the fluid viscosity and air velocity changes. (author)

  13. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    NASA Astrophysics Data System (ADS)

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M.; Gallego, Luis J.; Varela, Luis M.

    2015-09-01

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF6]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO3]- and [PF6]- anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca2+ cations. No qualitative difference with

  14. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids.

    PubMed

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M; Gallego, Luis J; Varela, Luis M

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF6]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO3](-) and [PF6](-) anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca(2+) cations. No qualitative

  15. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    SciTech Connect

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M.; Lynden-Bell, Ruth M.

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF{sub 6}]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO{sub 3}]{sup −} and [PF{sub 6}]{sup −} anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca{sup 2

  16. Measurement of the thermal conductivity of KNO3-NaNO3 mixtures using a transient hot-wire method with a liquid metal in a capillary probe

    NASA Astrophysics Data System (ADS)

    Omotani, T.; Nagasaka, Y.; Nagashima, A.

    1982-03-01

    The thermal conductivity of KNO3-NaNO3 mixtures was measured by a modified transient hot-wire method using liquid metal in a capillary as a heat source. The method was developed for measurements on electrically conducting liquids at high temperatures. Measurements were performed on pure NaNO3 and its three mixtures with KNO3 in the temperature range from 498 to 593 K.

  17. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    Prof. P. Somasundaran

    2002-09-30

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Surfactant loss by adsorption or precipitation depends to a great extent on the type of surfactant complexes and aggregates formed. Such information as well as techniques to generate the information is lacking currently particularly for surfactant mixtures and surfactant/polymer systems. A novel analytical centrifuge application is explored during the last period to generate information on structures-performance relationship for different surfactant aggregates in solution and, in turn, at interfaces. To use analytical untracentrifuge for surfactant mixtures, information on partial specific volumes of single surfactants and their mixtures is required. Towards this purpose, surface tension and density measurements were performed to determine critical micellar concentrations (cmc), partial specific volumes of n-dodecyl-{beta}-Dmaltoside (DM), nonyl phenol ethoxylated decyl ether (NP-10) and their 1:1 mixtures at 25 C. Durchschlag's theoretical calculation method was adopted to calculate the partial specific volumes. Effects of temperature and mixing, as well as methods used for estimation on micellization and partial specific volumes were studied during the current period. Surface tension results revealed no interaction between the two surfactants in mixed micelles. Partial specific volume measurements also indicated no interaction in mixed micelles. Maximum adsorption density, area per molecule and free energy of micellization were also calculated. Partial specific volumes were estimated by two experimental methods: d{sub {rho}}/dc and V{sub {sigma}}. The difference between the results of using the two methods is within 0.5% deviation. It was found that the partial specific volume is concentration dependent and sensitive to changes in temperature. The information generated in this study will be used for the study of surfactant aggregate mass distribution

  18. Thermodynamic analysis of multicomponent working fluids for Rankine bottoming cycle applications

    SciTech Connect

    Ash, J.E.

    1984-01-01

    The basic equations underlying a computer code are developed to describe the thermodynamic behavior of multicomponent working fluids in Rankine cycles. The code is to be employed in the performance analysis of Rankine bottoming cycle systems. The performance of such systems depends strongly on the working fluid characteristics. The introduction of multicomponent mixtures makes available a broad spectrum of fluid properties achievable by varying the mixture composition. The code provides a tool to analytically vary the mixture composition to optimize cycle performance.

  19. Mechanism of graphene formation by graphite electro-exfoliation in ionic liquids-water mixtures

    NASA Astrophysics Data System (ADS)

    Xu, Junli; Shi, Zhongning; Zhang, Xia; Haarberg, Geir Martin

    2014-12-01

    Graphene was produced from graphite electrode by exfoliation in ionic liquid. The influences of process parameters such as ionic liquid concentration, electrolysis potential and the type of anions in the ionic liquid on the production of graphene were studied, and a new mechanism is proposed. The results show that the increase of ionic liquid concentration is beneficial for the formation of graphene, and it is easier to produce graphene by increasing the applied voltage. Ionic liquids anions have great effect on the production of graphene. Both graphite anode and graphite cathode can be modified to graphene during electrolysis. Gases formed inside of the electrode play an important role for the production of graphene, while ionic liquids serve to accelerate the switching rate of graphite to graphene.

  20. Nonideal equilibrium dissolution of trichloroethene from a decane-based nonaqueous phase liquid mixture: Experimental and modeling investigation

    NASA Astrophysics Data System (ADS)

    McCray, John E.; Dugan, Pamela J.

    2002-07-01

    Batch equilibrium solubility studies were conducted to examine the solubilization behavior of a chlorinated solvent, trichloroethene (TCE), from a fuel-based nonaqueous phase liquid (NAPL) mixture. An alkane (n-decane) was used as a model compound because it is often a primary compound in jet fuel. The NAPL phase mole fractions of the chlorinated solvent in the mixture (XTCEN) that were investigated are typical of in situ values found at industrial and military waste sites (0.0001 >= XTCEN <= 0.1). The measured aqueous concentrations of TCE were essentially equal to the concentrations predicted with ideal dissolution theory (Raoult's law) at XTCEN values near 0.1. However, the ratio of the measured concentration to the ideal concentration, or the NAPL phase activity coefficient (γNTCE), increased nonlinearly as the XTCEN decreased. The γTCEN approached 6 at XTCEN = 0.0001. The UNIFAC method greatly underpredicts the γTCEN in this surrogate fuel. A NAPL-mixture equilibrium-dissolution model was developed that incorporates the observed nonideal dissolution. This model indicates that nonideal NAPL dissolution is 4 times faster than ideal dissolution for a hypothetical NAPL mixture with an initial XTCEN = 0.001. The magnitude of this effect becomes more important as the initial value of the XTCEN is decreased.

  1. Phase diagrams of binary mixtures of liquid crystals and rodlike polymers in the presence of an external field.

    PubMed

    Matsuyama, Akihiko; Ueda, Tomomi

    2012-06-14

    We theoretically study phase separations in mixtures of a low molecular-weight-liquid crystalline molecule (LC) and a rigid-rodlike polymer (rod) under an external field, such as magnetic or electric fields. By taking into account two orientational order parameters of the rod and the LC, we define four nematic phases (N(0), N(1), N(2), N(3)) on the temperature-concentration plane. Depending on the sign of the dielectric anisotropy Δε(i) of the rod (i = 1) and LC(i = 2), we examine the phase behavior of rod/LC mixtures in the case of Δε(1) > 0, Δε(2) > 0 (a), Δε(1) < 0, Δε(2) > 0 (b), Δε(1) > 0, Δε(2) < 0 (c), and Δε(1) < 0, Δε(2) < 0 (d). We predict a variety of phase separations induced by an external field. PMID:22713070

  2. Improved electrolytes for Li-ion batteries: Mixtures of ionic liquid and organic electrolyte with enhanced safety and electrochemical performance

    NASA Astrophysics Data System (ADS)

    Guerfi, A.; Dontigny, M.; Charest, P.; Petitclerc, M.; Lagacé, M.; Vijh, A.; Zaghib, K.

    Physical and electrochemical characteristics of Li-ion battery systems based on LiFePO 4 cathodes and graphite anodes with mixture electrolytes were investigated. The mixed electrolytes are based on an ionic liquid (IL), and organic solvents used in commercial batteries. We investigated a range of compositions to determine an optimum conductivity and non-flammability of the mixed electrolyte. This led us to examine mixtures of ILs with the organic electrolyte usually employed in commercial Li-ion batteries, i.e., ethylene carbonate (EC) and diethylene carbonate (DEC). The IL electrolyte consisted of (trifluoromethyl sulfonylimide) (TFSI) as anion and 1-ethyl-3-methyleimidazolium (EMI) as the cation. The physical and electrochemical properties of some of these mixtures showed an improvement characteristics compared to the constituents alone. The safety was improved with electrolyte mixtures; when IL content in the mixture is ≥40%, no flammability is observed. A stable SEI layer was obtained on the MCMB graphite anode in these mixed electrolytes, which is not obtained with IL containing the TFSI-anion. The high-rate capability of LiFePO 4 is similar in the organic electrolyte and the mixture with a composition of 1:1. The interface resistance of the LiFePO 4 cathode is stabilized when the IL is added to the electrolyte. A reversible capacity of 155 mAh g -1 at C/12 is obtained with cells having at least some organic electrolyte compared to only 124 mAh g -1 with pure IL. With increasing discharge rate, the capacity is maintained close to that in the organic solvent up to 2 C rate. At higher rates, the results with mixture electrolytes start to deviate from the pure organic electrolyte cell. The evaluation of the Li-ion cells; LiFePO 4//Li 4Ti 5O 12 with organic and, 40% mixture electrolytes showed good 1st CE at 98.7 and 93.0%, respectively. The power performance of both cell configurations is comparable up to 2 C rate. This study indicates that safety and

  3. Acoustically enhanced multicomponent NAPL ganglia dissolution in water saturated packed columns.

    PubMed

    Chrysikopoulos, Constantinos V; Vogler, Eric T

    2004-05-15

    The impact of acoustic pressure waves on multicomponent nonaqueous phase liquid (NAPL) ganglia dissolution in water saturated columns packed with glass beads was investigated. Laboratory data from dissolution experiments with two and three component NAPL mixtures suggested that acoustic waves significantly enhance ganglia dissolution due to the imposed oscillatory interstitial water velocity. The dissolution enhancement was shown to be directly proportional to the acoustic wave frequency. Furthermore, it was demonstrated that the greatest dissolution enhancement in the presence of acoustic waves is associated with the component of the NAPL mixture having the smallest equilibrium aqueous solubility. Finally, square shaped acoustic waves were shown to lead to greater NAPL dissolution enhancement compared to sinusoidal and triangular acoustic waves. The results of this study suggested that aquifer remediation using acoustic waves is a promising method particularly for aquifers contaminated with NAPLs containing components with very low equilibrium aqueous solubilities.

  4. Pattern evolution caused by dynamic coupling between wetting and phase separation in binary liquid mixture containing glass particles

    NASA Astrophysics Data System (ADS)

    Tanaka, Hajime; Lovinger, Andew J.; Davis, Don D.

    1994-04-01

    We demonstrate here that the pattern evolution in a binary liquid mixture containing glass spheres is strongly affected by the dynamic coupling between phase separation and wetting. Because of the difference in the wettability to glass between the two phases, the glass particles are preferentially included in the more wettable phase. The resulting pattern is strongly dependent on whether the spheres are mobile or immobile. For a high density of mobile particles, we find that an initially random pattern of spheres transforms into an ordered pattern because of geometrical confinement of particles into the more wettable phase.

  5. Experimental determination and prediction of (solid+liquid) phase equilibria for binary mixtures of heavy alkanes and fatty acids

    NASA Astrophysics Data System (ADS)

    Benziane, Mokhtar; Khimeche, Kamel; Dahmani, Abdellah; Nezar, Sawsen; Trache, Djalal

    2012-06-01

    Solid-liquid equilibria for three binary mixtures, n-Eicosane (1) + Lauric acid (2), n-Tetracosane (1) + Stearic acid (2), and n-Octacosane (1) + Palmitic acid (2), were measured using a differential scanning calorimeter. Simple eutectic behaviour was observed for these systems. The experimental results were correlated by means of the modified UNIFAC (Larsen and Gmehling versions), UNIQUAC and ideal models. The root-mean-square deviations of the solubility temperatures for all measured data vary from 0.26 to 3.15 K and depend on the particular model used. The best solubility correlation was obtained with the UNIQUAC model.

  6. New theories for smectic and nematic liquid-crystal polymers: Backbone LCPs (liquid crystalline polymers) and their mixtures and side-chain LCPs

    SciTech Connect

    Dowell, F.

    1987-01-01

    A summary of predictions and explanations from statistical-physics theories for both backbone and side-chain liquid crystalline polymers (LCPs) and for mixtures with backbone LCPs are presented. Trends in the thermodynamic and molecular ordering properties have been calculated as a function of pressure, density, temperature, and molecule chemical structures (including degree of polymerization and the following properties of the chemical structures of the repeat units: lengths and shapes, intra-chain rotation energies, dipole moments, site-site polarizabilities and Lennard-Jones potentials, etc.) in nematic and multiple smectic-A LC phases and in the isotropic liquid phase. The theoretical results are found to be in good agreement with existing experimental data. These theories can also be applied to combined LCPs. Since these theories have no ad hoc or arbitrarily adjustable parameters, these theories can be used to design new LCPs and new solvents as well as to predict and explain properties. 27 refs., 4 tabs.

  7. Molecular dynamics simulation of the behaviour of water in nano-confined ionic liquid-water mixtures

    NASA Astrophysics Data System (ADS)

    Docampo-Álvarez, B.; Gómez-González, V.; Montes-Campos, H.; Otero-Mato, J. M.; Méndez-Morales, T.; Cabeza, O.; Gallego, L. J.; Lynden-Bell, R. M.; Ivaništšev, V. B.; Fedorov, M. V.; Varela, L. M.

    2016-11-01

    This work describes the behaviour of water molecules in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid under nanoconfinement, between graphene sheets. By means of molecular dynamics simulations, the adsorption of water molecules at the graphene surface is studied. A depletion of water molecules in the vicinity of the neutral and negatively charged graphene surfaces, and their adsorption at the positively charged surface are observed in line with the preferential hydration of the ionic liquid anions. The findings are appropriately described using a two-level statistical model. The confinement effect on the structure and dynamics of the mixtures is thoroughly analyzed using the density and the potential of mean force profiles, as well as by the vibrational densities of the states of water molecules near the graphene surface. The orientation of water molecules and the water-induced structural transitions in the layer closest to the graphene surface are also discussed.

  8. Molecular dynamics simulation of the behaviour of water in nano-confined ionic liquid-water mixtures.

    PubMed

    Docampo-Álvarez, B; Gómez-González, V; Montes-Campos, H; Otero-Mato, J M; Méndez-Morales, T; Cabeza, O; Gallego, L J; Lynden-Bell, R M; Ivaništšev, V B; Fedorov, M V; Varela, L M

    2016-11-23

    This work describes the behaviour of water molecules in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid under nanoconfinement, between graphene sheets. By means of molecular dynamics simulations, the adsorption of water molecules at the graphene surface is studied. A depletion of water molecules in the vicinity of the neutral and negatively charged graphene surfaces, and their adsorption at the positively charged surface are observed in line with the preferential hydration of the ionic liquid anions. The findings are appropriately described using a two-level statistical model. The confinement effect on the structure and dynamics of the mixtures is thoroughly analyzed using the density and the potential of mean force profiles, as well as by the vibrational densities of the states of water molecules near the graphene surface. The orientation of water molecules and the water-induced structural transitions in the layer closest to the graphene surface are also discussed. PMID:27623714

  9. Non-exponential relaxation, fictive temperatures, and dispersive kinetics in the liquid-glass-liquid transition range of acetaminophen, sulfathiazole, and their mixtures

    NASA Astrophysics Data System (ADS)

    Aji, D. P. B.; Khouri, J.; Johari, G. P.

    2014-11-01

    To investigate the effects of added molecular heterogeneity on the hysteretic features of liquid-glass-liquid transition, we studied acetaminophen, sulfathiazole, and three of their mixtures by calorimetry, and determined the Tg and the fictive temperature, Tf, from changes in the enthalpy and entropy on the cooling and heating paths, as well as the non-exponential parameter, βcal. We find that, (i) Tf for cooling is within 1-3 K of Tf for heating and both are close to Tg, (ii) the closed loop entropy change in the liquid-glass-liquid range is negligibly small, (iii) Tg and Tf increase on increasing sulfathiazole in the mixture, (iv) βcal first slightly increases when the second component is added and then decreases, and (v) ageing causes deviations from a non-exponential, nonlinear behavior of the glass. In terms of fluctuations in a potential energy landscape, adding a solute heterogeneity would shift the state point to another part of the landscape with a different distribution of barrier heights and a different number of minima accessible to the state point. Part of the change in βcal is attributed to hydrogen-bond formation between the two components. Ageing changes the relaxation times distribution, more at short relaxation times than at long relaxation times, and multiplicity of relaxation modes implied by βcal < 1 indicates that each mode contributing to the enthalpy has its own Tg or Tf. βcal differs from βage determined from isothermal ageing, and the distribution parameter of α-relaxation times would differ from both βcal and βage.

  10. Electrical signatures of ethanol-liquid mixtures: implications for monitoring biofuels migration in the subsurface.

    PubMed

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-01-01

    Ethanol (EtOH), an emerging contaminant with potential direct and indirect environmental effects, poses threats to water supplies when spilled in large volumes. A series of experiments was directed at understanding the electrical geophysical signatures arising from groundwater contamination by ethanol. Conductivity measurements were performed at the laboratory scale on EtOH-water mixtures (0 to 0.97 v/v EtOH) and EtOH-salt solution mixtures (0 to 0.99 v/v EtOH) with and without a sand matrix using a conductivity probe and a four-electrode electrical measurement over the low frequency range (1-1000 Hz). A Lichtenecker-Rother (L-R) type mixing model was used to simulate electrical conductivity as a function of EtOH concentration in the mixture. For all three experimental treatments increasing EtOH concentration resulted in a decrease in measured conductivity magnitude (|σ|). The applied L-R model fitted the experimental data at concentration ≤0.4v/v EtOH, presumably due to predominant and symmetric intermolecular (EtOH-water) interaction in the mixture. The deviation of the experimental |σ| data from the model prediction at higher EtOH concentrations may be associated with hydrophobic effects of EtOH-EtOH interactions in the mixture. The |σ| data presumably reflected changes in relative strength of the three types of interactions (water-water, EtOH-water, and EtOH-EtOH) occurring simultaneously in EtOH-water mixtures as the ratio of EtOH to water changed. No evidence of measurable polarization effects at the EtOH-water and EtOH-water-mineral interfaces over the investigated frequency range was found. Our results indicate the potential for using electrical measurements to characterize and monitor EtOH spills in the subsurface.

  11. Electrical signatures of ethanol-liquid mixtures: implications for monitoring biofuels migration in the subsurface.

    PubMed

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-01-01

    Ethanol (EtOH), an emerging contaminant with potential direct and indirect environmental effects, poses threats to water supplies when spilled in large volumes. A series of experiments was directed at understanding the electrical geophysical signatures arising from groundwater contamination by ethanol. Conductivity measurements were performed at the laboratory scale on EtOH-water mixtures (0 to 0.97 v/v EtOH) and EtOH-salt solution mixtures (0 to 0.99 v/v EtOH) with and without a sand matrix using a conductivity probe and a four-electrode electrical measurement over the low frequency range (1-1000 Hz). A Lichtenecker-Rother (L-R) type mixing model was used to simulate electrical conductivity as a function of EtOH concentration in the mixture. For all three experimental treatments increasing EtOH concentration resulted in a decrease in measured conductivity magnitude (|σ|). The applied L-R model fitted the experimental data at concentration ≤0.4v/v EtOH, presumably due to predominant and symmetric intermolecular (EtOH-water) interaction in the mixture. The deviation of the experimental |σ| data from the model prediction at higher EtOH concentrations may be associated with hydrophobic effects of EtOH-EtOH interactions in the mixture. The |σ| data presumably reflected changes in relative strength of the three types of interactions (water-water, EtOH-water, and EtOH-EtOH) occurring simultaneously in EtOH-water mixtures as the ratio of EtOH to water changed. No evidence of measurable polarization effects at the EtOH-water and EtOH-water-mineral interfaces over the investigated frequency range was found. Our results indicate the potential for using electrical measurements to characterize and monitor EtOH spills in the subsurface. PMID:23159764

  12. Electrical signatures of ethanol-liquid mixtures: implications for monitoring biofuels migration in the subsurface

    USGS Publications Warehouse

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-01-01

    Ethanol (EtOH), an emerging contaminant with potential direct and indirect environmental effects, poses threats to water supplies when spilled in large volumes. A series of experiments was directed at understanding the electrical geophysical signatures arising from groundwater contamination by ethanol. Conductivity measurements were performed at the laboratory scale on EtOH–water mixtures (0 to 0.97 v/v EtOH) and EtOH–salt solution mixtures (0 to 0.99 v/v EtOH) with and without a sand matrix using a conductivity probe and a four-electrode electrical measurement over the low frequency range (1–1000 Hz). A Lichtenecker–Rother (L–R) type mixing model was used to simulate electrical conductivity as a function of EtOH concentration in the mixture. For all three experimental treatments increasing EtOH concentration resulted in a decrease in measured conductivity magnitude (|σ|). The applied L–R model fitted the experimental data at concentration ≤ 0.4 v/v EtOH, presumably due to predominant and symmetric intermolecular (EtOH–water) interaction in the mixture. The deviation of the experimental |σ| data from the model prediction at higher EtOH concentrations may be associated with hydrophobic effects of EtOH–EtOH interactions in the mixture. The |σ| data presumably reflected changes in relative strength of the three types of interactions (water–water, EtOH–water, and EtOH–EtOH) occurring simultaneously in EtOH–water mixtures as the ratio of EtOH to water changed. No evidence of measurable polarization effects at the EtOH–water and EtOH–water–mineral interfaces over the investigated frequency range was found. Our results indicate the potential for using electrical measurements to characterize and monitor EtOH spills in the subsurface.

  13. Thermodynamical and structural properties of binary mixtures of imidazolium chloride ionic liquids and alcohols from molecular simulation

    NASA Astrophysics Data System (ADS)

    Raabe, Gabriele; Köhler, Jürgen

    2008-10-01

    We have performed molecular dynamics simulations to determine the densities, excess energies of mixing, and structural properties of binary mixtures of the 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) [amim][Cl] and ethanol and 1-propanol in the temperature range from 298.15to363.15K. As in our previous work [J. Chem. Phys. 128, 154509 (2008)], our simulation studies are based on a united atom model from Liu et al. [Phys. Chem. Chem. Phys. 8, 1096 (2006)] for the 1-ethyl- and 1-butyl-3-methylimidazolium cations [emim+] and [bmim+], which we have extended to the 1-hexyl-3-methylimidazolium [hmim+] cation and combined with parameters of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] for the chloride anion [Cl-] and the force field by Khare et al. for the alcohols [J. Phys. Chem. B 108, 10071 (2004)]. With this, we provide both prediction for the densities of the mixtures that have mostly not been investigated experimentally yet and a molecular picture of the interactions between the alcohol molecules and the ions. The negative excess energies of all mixtures indicate an energetically favorable mixing of [amim][Cl] ILs and alcohols. To gain insight into the nonideality of the mixtures on the molecular level, we analyzed their local structures by radial and spatial distribution functions. These analyses show that the local ordering in these mixtures is determined by strong hydrogen-bond interactions between the chloride anion and the hydroxyls of the alcohols, enhanced interactions between the anion and the charged domain of the cation, and an increasing aggregation of the nonpolar alkyl tails of the alcohols and the cations with increasing cation size, which results in a segregation of polar and nonpolar domains.

  14. Large-scale inhomogeneities in solutions of low molar mass compounds and mixtures of liquids: supramolecular structures or nanobubbles?

    PubMed

    Sedlák, Marián; Rak, Dmytro

    2013-02-28

    In textbooks, undersaturated solutions of low molar mass compounds and mixtures of freely miscible liquids are considered as homogeneous at larger length scales exceeding appreciably dimensions of individual molecules. However, growing experimental evidence reveals that it is not the case. Large-scale structures with sizes on the order of 100 nm are present in solutions and mixtures used in everyday life and research practice, especially in aqueous systems. These mesoscale inhomogeneities are long-lived, and (relatively slow) kinetics of their formation can be monitored upon mixing the components. Nevertheless, the nature of these structures and mechanisms behind their formation are not clear yet. Since it was previously suggested that these can be nanobubbles stabilized by adsorbed solute at the gas/solvent interface, we devote the current study to addressing this question. Static and dynamic light scattering was used to investigate solutions and mixtures prepared at ordinary conditions (equilibrated with air at 1 atm), prepared with degassed solvent, and solutions and mixtures degassed after formation of large structures. The behavior of large structures in strong gravitational centrifugal fields was also investigated. Systems from various categories were chosen for this study: aqueous solutions of an inorganic ionic compound (MgSO4), organic ionic compound (citric acid), uncharged organic compound (urea), and a mixture of water with organic solvent freely miscible with water (tert-butyl alcohol). Obtained results show that these structures are not nanobubbles in all cases. Visualization of large-scale structures via nanoparticle tracking analysis is presented. NTA results confirm conclusions from our previous light scattering work.

  15. Near-infrared imaging of liquid mixtures utilizing multi-channel photonic crystal wavelength filters.

    PubMed

    Mitsuhashi, Masahiro; Ohtera, Yasuo; Yamada, Hirohito

    2014-09-15

    We demonstrate a near-infrared (NIR) spectroscopy-based real-time imaging system of aqueous alcohol solutions (ethanol containing water). The system obtains a set of NIR images by the combination of an InGaAs area sensor and four-channel patterned photonic crystal wavelength filters. Acquired pictures were decomposed into a set of NIR images and processed by principal component analysis (PCA). According to a preliminary experiment for water/ethanol mixture samples, we confirmed that the system was capable of identifying the mixture ratio with accuracy of the order of a few percentage points at a frame rate of approximately 24 frames per second (fps). PMID:26466256

  16. Analytical strategy to reveal the in vivo process of multi-component herbal medicine: a pharmacokinetic study of licorice using liquid chromatography coupled with triple quadrupole mass spectrometry.

    PubMed

    Qiao, Xue; Ye, Min; Xiang, Cheng; Wang, Qing; Liu, Chun-Fang; Miao, Wen-Juan; Guo, De-An

    2012-10-01

    Although various techniques have been employed to analyze drug metabolites, the metabolism of multi-component herbal medicine has seldom been fully addressed. In contrast to chemical drugs, a number of compounds in herbal medicine could get into circulation and then be metabolized. Moreover, these compounds may have metabolic interactions which make their pharmacokinetics (PK) even more complicated. The present work aims to elucidate the multi-component pharmacokinetics of a herbal medicine, and to demonstrate how PK behaviors were altered by co-existing constituents. Licorice (Glycyrrhiza uralensis Fisch.), a most commonly used herbal medicine, was chosen as a model. A strategy was proposed to compare the PK profiles of licorice extract with those of nine single compounds. These compounds were major bioactive constituents of licorice, and represented various structural types (flavanone, chalcone, isoflavone, saponin, and coumarin). We established a segmented selected reaction monitoring LC/MS/MS method to simultaneously monitor 63 licorice metabolites in rat plasma, and obtained the PK profiles of 55 metabolites. The results indicated that interactions among licorice compounds altered their PK behaviors in 4 aspects: improvement in bioavailability for aglycones (133- and 109-fold increase for liquiritigenin and isoliquiritigenin, respectively), prolongation in system circulation for glycosides (0.3h delay in T(max) for liquiritin apioside and isoliquiritin apioside), decrease of potential toxicity for saponins such as glycyrrhizic acid, and shift in plasma distribution for phase II metabolites. This is the first attempt to systematically reveal the in vivo process of licorice. Moreover, the study indicates noticeable interactions to alter pharmacokinetics among licorice compounds, which may be characteristic for herbal medicines.

  17. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    Prof. P. Somasundaran

    2003-03-31

    The aim of the project is to develop a knowledge base to help with the design of enhanced process for mobilizing and extracting untrapped oil. We emphasize on evaluating novel surfactant mixtures and on obtaining optimum combinations of the surfactants in chemical flooding EOR process. An understanding of the micellar shape and size is crucial since these physical properties directly determine the crude oil removal efficiency. Analytical ultracentrifugation experiments were used to test the multi-micelle model proposed earlier and formulate the relationships between mixed micelle formation and the surfactant structure. Information on partial specific volume of surfactants and their mixtures is required to treat analytical ultracentrifuge data. In the last report, it was noted that the partial specific volumes of the sugar-based surfactants obtained experimentally did not agree with those from theoretical calculations. A scrutiny of partial specific volumes of the four sugar-based surfactants revealed that conformational changes upon micelle formation are responsible for the large deviation. From sedimentation equilibrium experiments, two types of micelles were identified for the nonionic polyethylene surfactant and its mixtures with the sugar-based surfactant, dodecyl maltoside. The average aggregation numbers of n-dodecyl-{beta}-D-maltoside and nonyl phenol ethoxylated decyl ether agreed with those reported in literature using other techniques. Our study displayed, for the first time, that small micelles might coexist with large micelles at high concentrations due to unique structures of the surfactant although classical thermodynamic theory supports only one type of micelle. Initial dynamic light scattering results support the results for the same mixed surfactant system from analytical ultracentrifuge equilibrium technique. The implication of this finding lies in the fact that efficiency of oil recovery will be improved due to the large micellar size, its

  18. A Computationally Efficient Multicomponent Equilibrium Solver for Aerosols (MESA)

    SciTech Connect

    Zaveri, Rahul A.; Easter, Richard C.; Peters, Len K.

    2005-12-23

    This paper describes the development and application of a new multicomponent equilibrium solver for aerosol-phase (MESA) to predict the complex solid-liquid partitioning in atmospheric particles containing H+, NH4+, Na+, Ca2+, SO4=, HSO4-, NO3-, and Cl- ions. The algorithm of MESA involves integrating the set of ordinary differential equations describing the transient precipitation and dissolution reactions for each salt until the system satisfies the equilibrium or mass convergence criteria. Arbitrary values are chosen for the dissolution and precipitation rate constants such that their ratio is equal to the equilibrium constant. Numerically, this approach is equivalent to iterating all the equilibrium reactions simultaneously with a single iteration loop. Because CaSO4 is sparingly soluble, it is assumed to exist as a solid over the entire RH range to simplify the algorithm for calcium containing particles. Temperature-dependent mutual deliquescence relative humidity polynomials (valid from 240 to 310 K) for all the possible salt mixtures were constructed using the comprehensive Pitzer-Simonson-Clegg (PSC) activity coefficient model at 298.15 K and temperature-dependent equilibrium constants in MESA. Performance of MESA is evaluated for 16 representative mixed-electrolyte systems commonly found in tropospheric aerosols using PSC and two other multicomponent activity coefficient methods – Multicomponent Taylor Expansion Method (MTEM) of Zaveri et al. [2004], and the widely-used Kusik and Meissner method (KM), and the results are compared against the predictions of the Web-based AIM Model III or available experimental data. Excellent agreement was found between AIM, MESA-PSC, and MESA-MTEM predictions of the multistage deliquescence growth as a function of RH. On the other hand, MESA-KM displayed up to 20% deviations in the mass growth factors for common salt mixtures in the sulfate-poor cases while significant discrepancies were found in the predicted multistage

  19. An Innovative Technique of Liquid Purity Analysis and Its Application to Analysis of Water Concentration in Alcohol-Water Mixtures and Studies on Change of Activation Energies of the Mixtures

    NASA Astrophysics Data System (ADS)

    de, Dilip; Aziz Dikko, Abdul

    2012-10-01

    The activation energy of a liquid molecule and hence its viscosity coefficient changes with addition of contaminants to the original liquid. This forms the basis of a new technology for analysis of purity of the liquid. We discovered that concentration of certain contaminants such as water in alcohol or vice versa can be uniquely and accurately determined in a short time (about 10-15 minutes) using a simple and yet innovative technique that only requires measurement of time of flow of the impure liquid (say, water-alcohol mixture) and distilled water through a simple viscometer designed and constructed for this purpose. We find that the viscosity coefficient μ of alcohol increased almost linearly with water concentration at a rate that depends on the type of alcohol and water concentration. We determined the increase of activation energy of alcohol molecules with increase of water concentration. This increase also depends on type of alcohol. Our detailed investigation on alcohol-water mixtures for both ethyl and methyl alcohol along with discussion on possible future potential application of such a simple, yet very reliable inexpensive technique for liquid purity analysis is presented. A comparison is made of our present method with other methods on the accuracies, problems and reliability of impurity analysis in liquids. A part of the quantum theory of viscosity of liquid mixtures that is in the developmental stage in order to explain some of the observed properties is presented.

  20. The use of positron spectroscopy for revealing the nanosized structures in liquid mixtures. Identification of n-propanol nanoagglomerates in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Stepanov, P. S.; Byakov, V. M.; Zaluzhnyi, A. G.

    2014-04-01

    The potential of positron spectroscopy for identification of nanosized structures in liquid mixtures, which is a difficult problem that still remains a challenge in physical chemistry of liquids, was demonstrated. The water- n-propanol mixtures were chosen as an example. An analysis of the concentration dependences of the mean lifetime of ortho-positronium atoms in water- n-propanol binary mixtures and water-propanol mixtures containing CoCl2 (0.4 M) and Co(ClO4)2 (0.6 M) suggested that the water- n-propanol mixture with ˜0.1 to ˜0.4 mole fractions of propanol resembled an emulsion of alcohol nanodrops suspended in water.

  1. Correlation between the fluorescent response of microfluidity probes and the water content and viscosity of ionic liquid and water mixtures.

    PubMed

    Pandey, Siddharth; Fletcher, Kristin A; Baker, Sheila N; Baker, Gary A

    2004-07-01

    Accurate data on transport properties such as viscosity are essential in plant and process design involving ionic liquids. In this study, we determined the absolute viscosity of the ionic liquid + water system at water mole fractions from 0 to 0.25 for three 1-alkyl-3-methylimidazolium ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide. In each case, the excimer to monomer ratio for 1,m-bis(1-pyrenyl)alkanes (m= 3 or 10) was found to increase linearly with the mole fraction of water. Of the probes studied only PRODAN and rhodamine 6G, both of which have the ability to participate in hydrogen bonding, exhibited Perrin hydrodynamic behavior in the lower viscosity bis(trifluoromethane sulfonyl)imides. As a result, these probes allow for the extrapolation of the absolute viscosity of the ionic liquid mixture from the experimental fluorescence steady-state polarization values.

  2. Description of concentration fluctuations in liquid binary mixtures with nonadditive potentials

    SciTech Connect

    Osman, S.M.; Singh, R.N. )

    1995-01-01

    The segregation or phase separation in a binary mixture is investigated within a quasilattice model and the hard-sphere-like model. The hard-sphere results are improved by incorporating a nonadditive attractive tail interaction. An analytic expression for the concentration fluctuation [ital S][sub [ital c][ital c

  3. Ternary mixtures of ionic liquids for better salt solubility, conductivity and cation transference number improvement

    PubMed Central

    Karpierz, E.; Niedzicki, L.; Trzeciak, T.; Zawadzki, M.; Dranka, M.; Zachara, J.; Żukowska, G. Z.; Bitner-Michalska, A.; Wieczorek, W.

    2016-01-01

    We hereby present the new class of ionic liquid systems in which lithium salt is introduced into the solution as a lithium cation−glyme solvate. This modification leads to the reorganisation of solution structure, which entails release of free mobile lithium cation solvate and hence leads to the significant enhancement of ionic conductivity and lithium cation transference numbers. This new approach in composing electrolytes also enables even three-fold increase of salt concentration in ionic liquids. PMID:27767069

  4. On the collective network of ionic liquid/water mixtures. III. Structural analysis of ionic liquids on the basis of Voronoi decomposition.

    PubMed

    Schröder, C; Neumayr, G; Steinhauser, O

    2009-05-21

    Three different mixtures of 1-butyl-3-methyl-imidazolium tetrafluoroborate with water have been studied by means of molecular dynamics simulations. Based on the classical Lopes-Padua force field trajectories of approximately 60 ns were computed. This is the third part of a series concerning the collective network of 1-butyl-3-methyl-imidazolium tetrafluoroborate/water mixtures. The first part [C. Schröder et al., J. Chem. Phys. 127, 234503 (2007)] dealt with the orientational structure and static dielectric constants. The second part [C. Schröder et al., J. Chem. Phys. 129, 184501 (2008)] was focused on the decomposition of the dielectric spectrum of these mixtures. In this work the focus lies on the characterization of the neighborhood of ionic liquids by means of the Voronoi decomposition. The Voronoi algorithm is a rational tool to uniquely decompose the space around a reference molecule without using any empirical parameters. Thus, neighborhood relations, direct and indirect ones, can be extracted and were used in combination with g-coefficients. These coefficients represent the generalization of the traditional radial distribution function in order to include the mutual positioning and orientation of anisotropic molecules. Furthermore, the Voronoi method provides, as a by-product, the mutual coordination numbers of molecular species.

  5. Perturbation theory of structure in classical liquid mixtures: Application to metallic systems near phase separation. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Henderson, R. L.

    1974-01-01

    The partial structure factors of classical simple liquid mixtures near phase separation are dicussed. The theory is developed for particles interacting through pair potentials, and is thus appropriate both to insulating fluids, and also to metallic systems if these may be described by an effective ion-ion pair interaction. The motivation arose from consideration of metallic liquid mixtures, in which resistive anomalies have been observed near phase separation. A mean field theory correction appropriate to 3 pair potential for the effects of correlated motions in the reference fluid is studied. The work is cast in terms of functions which are closely related to the direct correlation functions of Ornstein and Zernike. The results are qualitatively in accord with physical expectations. Quantitative agreement with experiment seems to turn on the selection of the hard core reference potential in terms of the metallic effective pair potential. It is suggested that the present effective pair potentials are perhaps not properly used to calculate the metallic structure factors at long wavelength.

  6. Molecular Dynamics Simulations of the Ionic Liquid 1-n-Butyl-3-Methylimidazolium Chloride and Its Binary Mixtures with Ethanol.

    PubMed

    Chen, Mo; Pendrill, Robert; Widmalm, Göran; Brady, John W; Wohlert, Jakob

    2014-10-14

    Room temperature ionic liquids (ILs) of the imidazolium family have attracted much attention during the past decade for their capability to dissolve biomass. Besides experimental work, numerous compuational studies have been concerned with the physical properties of both neat ILs and their interactions with different solutes, in particular, carbohydrates. Many classical force fields designed specifically for ILs have been found to yield viscosities that are too high for the liquid state, which has been attributed to the fact that the effective charge densities are too high due to the lack of electronic polarizability. One solution to this problem has been uniform scaling of the partial charges by a scale factor in the range 0.6-0.9, depending on model. This procedure has been shown to improve the viscosity of the models, and also to positively affect other properties, such as diffusion constants and ionic conductivity. However, less attention has been paid to how this affects the overall thermodynamics of the system, and the problems it might create when the IL models are combined with other force fields (e.g., for solutes). In the present work, we employ three widely used IL force fields to simulate 1-n-butyl-3-methyl-imidazolium chloride in both the crystal and the liquid state, as well as its binary mixture with ethanol. Two approaches are used: one in which the ionic charge is retained at its full integer value and one in which the partial charges are uniformly reduced to 85%. We investigate and calculate crystal and liquid structures, molar heat capacities, heats of fusion, self-diffusion constants, ionic conductivity, and viscosity for the neat IL, and ethanol activity as a function of ethanol concentration for the binary mixture. We show that properties of the crystal are less affected by charge scaling compared to the liquid. In the liquid state, transport properties of the neat IL are generally improved by scaling, whereas values for the heat of fusion are

  7. Docosahexaenoic acid promotes micron scale liquid-ordered domains. A comparison study of docosahexaenoic versus oleic acid containing phosphatidylcholine in raft-like mixtures.

    PubMed

    Georgieva, R; Chachaty, C; Hazarosova, R; Tessier, C; Nuss, P; Momchilova, A; Staneva, G

    2015-06-01

    The understanding of the functional role of the lipid diversity in biological membranes is a major challenge. Lipid models have been developed to address this issue by using lipid mixtures generating liquid-ordered (Lo)/liquid-disordered (Ld) immiscibility. The present study examined mixtures comprising Egg sphingomyelin (SM), cholesterol (chol) and phosphatidylcholine (PC) either containing docosahexaenoic (PDPC) or oleic acid (POPC). The mixtures were examined in terms of their capability to induce phase separation at the micron- and nano-scales. Fluorescence microscopy, electron spin resonance (ESR), X-ray diffraction (XRD) and calorimetry methods were used to analyze the lateral organization of the mixtures. Fluorescence microscopy of giant vesicles could show that the temperature of the micron-scale Lo/Ld miscibility is higher for PDPC than for POPC ternary mixtures. At 37°C, no micron-scale Lo/Ld phase separation could be identified in the POPC containing mixtures while it was evident for PDPC. In contrast, a phase separation was distinguished for both PC mixtures by ESR and XRD, indicative that PDPC and POPC mixtures differed in micron vs nano domain organization. Compared to POPC, the higher line tension of the Lo domains observed in PDPC mixtures is assumed to result from the higher difference in Lo/Ld order parameter rather than hydrophobic mismatch.

  8. Study and characterization of the smectic X* phase in binary mixtures of thermotropic double hydrogen bonded ferroelectric liquid crystals

    NASA Astrophysics Data System (ADS)

    Sangameswari, G.; Pongali Sathya Prabu, N.; Madhu Mohan, M. L. N.

    2015-09-01

    Thermotropic double hydrogen bonded ferroelectric liquid crystals (DHBFLCs) composed of N-carbamyl-L-glutamic acid (CGA) and p-n-alkyloxy benzoic acids (BAO) have been investigated. Variation in the molar proportion of X and Y (where X = CGA + 5BAO and Y = CGA + 6BAO, CGA + 7BAO, and CGA + 8BAO) composed of three series yielded 27 binary mixtures. Optical and thermal properties of these mixtures are meticulously studied in the present article. A novel smectic ordering, namely smectic X*, is observed in all the three series. The aim of the investigation is to obtain an abundance occurrence of smectic X* and hence the proportions of the binary mixtures are so chosen that the preamble task is accomplished. Phase diagrams of three series are constructed from the data obtained from polarizing optical microscope (POM) and differential scanning calorimetry (DSC) studies. Odd-even effect, order of the phase transition, thermal stability factor, thermal equilibrium, and optical tilt angle are also premeditated.

  9. Non-invasive determination of ethanol, propylene glycol and water in a multi-component pharmaceutical oral liquid by direct measurement through amber plastic bottles using Fourier transform near-infrared spectroscopy.

    PubMed

    Broad, N W; Jee, R D; Moffat, A C; Eaves, M J; Mann, W C; Dziki, W

    2000-11-01

    Fourier transform near-infrared (FT-NIR) spectroscopy was used to quantify rapidly the ethanol (34-49% v/v), propylene glycol (20-35% v/v) and water (11-20% m/m) contents within a multi-component pharmaceutical oral liquid by measurement directly through the amber plastic bottle packaging. Spectra were collected in the range 7302-12,000 cm-1 and calibration models set-up using partial least-squares regression (PLSR) and multiple linear regression. Reference values for the three components were measured using capillary gas chromatography (ethanol and propylene glycol) and Karl Fischer (water) assay procedures. The calibration and test sets consisted of production as well as laboratory batches that were made to extend the concentration ranges beyond the natural production variation. The PLSR models developed gave standard errors of prediction (SEP) of 1.1% v/v for ethanol, 0.9% v/v for propylene glycol and 0.3% m/m for water. For each component the calibration model was validated in terms of: linearity, repeatability, intermediate precision and robustness. All the methods produced statistically favourable outcomes. Ten production batches independent of the calibration and test sets were also challenged against the PLSR models, giving SEP values of 1.3% v/v (ethanol), 1.0% v/v (propylene glycol) and 0.2% m/m (water). NIR transmission spectroscopy allowed all three liquid constituents to be non-invasively measured in under 1 min.

  10. BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    Prof. P. Somasundaran

    2002-03-01

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.

  11. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    P. Somasundaran

    2004-11-20

    The aim of the project is to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untrapped oil. We emphasize evaluation of novel surfactant mixtures and obtaining optimum combinations of the surfactants for efficient chemical flooding EOR processes. In this regard, an understanding of the aggregate shape, size and structure is crucial since these properties govern the crude oil removal efficiency. During the three-year period, the adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants have been studied. Sugar-based surfactants are made from renewable resources, nontoxic and biodegradable. They are miscible with water and oil. These environmentally benign surfactants feature high surface activity, good salinity, calcium and temperature tolerance, and unique adsorption behavior. They possess the characteristics required for oil flooding surfactants and have the potential for replacing currently used surfactants in oil recovery. A novel analytical ultracentrifugation technique has been successfully employed for the first time, to characterize the aggregate species present in mixed micellar solution due to its powerful ability to separate particles based on their size and shape and monitor them simultaneously. Analytical ultracentrifugation offers an unprecedented opportunity to obtain important information on mixed micelles, structure-performance relationship for different surfactant aggregates in solution and their role in interfacial processes. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. Four softwares: OptimaTM XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity

  12. A comparative study of room temperature ionic liquids and their organic solvent mixtures near charged electrodes

    NASA Astrophysics Data System (ADS)

    Vatamanu, Jenel; Vatamanu, Mihaela; Borodin, Oleg; Bedrov, Dmitry

    2016-11-01

    The structural properties of electrolytes consisting of solutions of ionic liquids in a polar solvent at charged electrode surfaces are investigated using classical atomistic simulations. The studied electrolytes consisted of tetraethylammonium tetrafluoroborate (NEt4-BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate (c2mim-BF4) and 1-octyl-3-methylimidazolium tetrafluoroborate (c8mim-BF4) salts dissolved in acetonitrile solvent. We discuss the influence of electrolyte concentration, chemical structure of the ionic salt, temperature, conducting versus semiconducting nature of the electrode, electrode geometry and surface roughness on the electric double layer structure and capacitance and compare these properties with those obtained for pure room temperature ionic liquids. We show that electrolytes consisting of solutions of ions can behave quite differently from pure ionic liquid electrolytes.

  13. A comparative study of room temperature ionic liquids and their organic solvent mixtures near charged electrodes.

    PubMed

    Vatamanu, Jenel; Vatamanu, Mihaela; Borodin, Oleg; Bedrov, Dmitry

    2016-11-23

    The structural properties of electrolytes consisting of solutions of ionic liquids in a polar solvent at charged electrode surfaces are investigated using classical atomistic simulations. The studied electrolytes consisted of tetraethylammonium tetrafluoroborate (NEt4-BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate (c2mim-BF4) and 1-octyl-3-methylimidazolium tetrafluoroborate (c8mim-BF4) salts dissolved in acetonitrile solvent. We discuss the influence of electrolyte concentration, chemical structure of the ionic salt, temperature, conducting versus semiconducting nature of the electrode, electrode geometry and surface roughness on the electric double layer structure and capacitance and compare these properties with those obtained for pure room temperature ionic liquids. We show that electrolytes consisting of solutions of ions can behave quite differently from pure ionic liquid electrolytes. PMID:27623976

  14. Nanostructures of Liquid Crystal Phases in Mixtures of Bent-core and Rod-shaped Molecules

    SciTech Connect

    S Hong; R Verduzco; J Gleeson; S Sprunt; A Jakli

    2011-12-31

    We report small angle x-ray scattering (SAXS) studies of isotropic, nematic, and smectic mesophases formed by binary mixtures of bent-core (BC) and rod-shaped (RS) molecules. While optical studies indicate that the components are fully miscible, SAXS reveals fascinating structures that are consistent with segregation on a nanoscopic scale. We find that tilted smectic clusters, which have been previously reported in both the nematic and isotropic states of the pure BC materials, are also present in mixtures with up to 50 wt% of the RS compound; this is consistent with previous dielectric and flexoelectric studies on such mixtures. Unexpectedly in this concentration range the clusters are present in the isotropic and in the induced smectic phase range, as well as throughout the nematic phase. The results in the smectic phase also reveal complex layering phenomena, providing important insight into the interaction between bent and rod-shaped molecules. These studies will be crucial in the design of promising new functional nanomaterials.

  15. Nanostructures of liquid crystal phases in mixtures of bent-core and rod-shaped molecules

    SciTech Connect

    Hong, S. H.; Gleeson, J. T.; Sprunt, S.; Verduzco, R.; Jakli, A.

    2011-06-15

    We report small angle x-ray scattering (SAXS) studies of isotropic, nematic, and smectic mesophases formed by binary mixtures of bent-core (BC) and rod-shaped (RS) molecules. While optical studies indicate that the components are fully miscible, SAXS reveals fascinating structures that are consistent with segregation on a nanoscopic scale. We find that tilted smectic clusters, which have been previously reported in both the nematic and isotropic states of the pure BC materials, are also present in mixtures with up to 50 wt% of the RS compound; this is consistent with previous dielectric and flexoelectric studies on such mixtures. Unexpectedly in this concentration range the clusters are present in the isotropic and in the induced smectic phase range, as well as throughout the nematic phase. The results in the smectic phase also reveal complex layering phenomena, providing important insight into the interaction between bent and rod-shaped molecules. These studies will be crucial in the design of promising new functional nanomaterials.

  16. Nanostructures of liquid crystal phases in mixtures of bent-core and rod-shaped molecules.

    PubMed

    Hong, S H; Verduzco, R; Gleeson, J T; Sprunt, S; Jákli, A

    2011-06-01

    We report small angle x-ray scattering (SAXS) studies of isotropic, nematic, and smectic mesophases formed by binary mixtures of bent-core (BC) and rod-shaped (RS) molecules. While optical studies indicate that the components are fully miscible, SAXS reveals fascinating structures that are consistent with segregation on a nanoscopic scale. We find that tilted smectic clusters, which have been previously reported in both the nematic and isotropic states of the pure BC materials, are also present in mixtures with up to 50 wt% of the RS compound; this is consistent with previous dielectric and flexoelectric studies on such mixtures. Unexpectedly in this concentration range the clusters are present in the isotropic and in the induced smectic phase range, as well as throughout the nematic phase. The results in the smectic phase also reveal complex layering phenomena, providing important insight into the interaction between bent and rod-shaped molecules. These studies will be crucial in the design of promising new functional nanomaterials.

  17. Proton transfer and polarity changes in ionic liquid-water mixtures: a perspective on hydrogen bonds from ab initio molecular dynamics at the example of 1-ethyl-3-methylimidazolium acetate-water mixtures--part 1.

    PubMed

    Brehm, Martin; Weber, Henry; Pensado, Alfonso S; Stark, Annegret; Kirchner, Barbara

    2012-04-21

    The ionic liquid 1-ethyl-3-methylimidazolium acetate [C(2)C(1)Im][OAc] shows a great potential to dissolve strongly hydrogen bonded materials, related with the presence of a strong hydrogen bond network in the pure liquid. A first step towards understanding the solvation process is characterising the hydrogen bonding ability of the ionic liquid. The description of hydrogen bonds in ionic liquids is a question under debate, given the complex nature of this media. The purpose of the present article is to rationalise not only the existence of hydrogen bonds in ionic liquids, but also to analyse their influence on the structure of the pure liquid and how the presence of water, an impurity inherent to ionic liquids, affects this type of interaction. We perform an extensive study using ab initio molecular dynamics on the structure of mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate with water, at different water contents. Hydrogen bonds are present in the pure liquid, and the presence of water modifies and largely disturbs the hydrogen bond network of the ionic liquid, and also affects the formation of other impurities (carbenes) and the dipole moment of the ions. The use of ab initio molecular dynamics is the recommended tool to explore hydrogen bonding in ionic liquids, as an explicit electronic structure calculation is combined with the study of the condensed phase.

  18. Infrared spectroscopy of methanol-hexane liquid mixtures. II. The strength of hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Chapados, Camille

    2009-03-01

    The study by Fourier transform infrared attenuated total reflectance spectroscopy at 27 °C of methanol (MeOH) and hexane mixtures is presented. In the 0-0.25 and 0.75-1.00 molar fractions, the mixtures form homogeneous solutions, whereas from 0.25 to 0.75, the mixtures are inhomogeneous forming two phases. These mixtures have the near 3300 cm-1 OH stretch band only slightly displaced throughout the whole concentration range indicating very little variation in the H-bonding condition. This result is very different from that of MeOH in CCl4 where the OH stretch bands are scattered in a wide frequency range. Factor analysis applied to the MeOH/hexane spectra gave seven principal factors (one hexane and six methanol factors) and retrieved their principal spectra and abundances. In the inhomogeneous region, the two phase volumes changed inversely with concentration, but their factor compositions are invariable at 1:3 and 3:1 molar ratios. Five of the six principal methanol factors have the O-H and the C-O stretch bands situated near, respectively, 3310 and 1025 cm-1 with little displacement in the whole concentration range. The sixth factor observed at 3654 cm-1 (full width at half height<40 cm-1) was assigned to free methanol OH by Max and Chapados [J. Chem. Phys. 128, 224512 (2008)]. This species concentration is very low but constant at around 0.01M in the methanol range of 0.5-2.5M. The main OH stretch bands (˜3300 cm-1) were simulated with six Gaussian components that were assigned to different hydrogen-bonding situations. These form reverse micelles at low methanol concentrations and micelles at high concentrations that persist in pure methanol. A very different state of affairs exists in MeOH in CCl4 where free OH groups are formed in almost all mixtures except in pure MeOH. Since hexane is a better model of a lipidic milieu than CCl4, the results for MeOH/hexane give a better representation of the fate of alcoholic OH groups in such a milieu.

  19. Solvation dynamics in a prototypical ionic liquid + dipolar aprotic liquid mixture: 1-butyl-3-methylimidazolium tetrafluoroborate + acetonitrile.

    PubMed

    Liang, Min; Zhang, Xin-Xing; Kaintz, Anne; Ernsting, Nikolaus P; Maroncelli, Mark

    2014-02-01

    Solvation energies, rotation times, and 100 fs to 20 ns solvation response functions of the solute coumarin 153 (C153) in mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([Im41][BF4]) + acetonitrile (CH3CN) at room temperature (20.5 °C) are reported. Available density, shear viscosity, and electrical conductivity data at 25 °C are also collected and parametrized, and new data on refractive indices and component diffusion coefficients presented. Solvation free energies and reorganization energies associated with the S0 ↔ S1 transition of C153 are slightly (≤15%) larger in neat [Im41][BF4] than in CH3CN. No clear evidence for preferential solvation of C153 in these mixtures is found. Composition-dependent diffusion coefficients (D) of Im41(+) and CH3CN as well as C153 rotation times (τ) are approximately related to solution viscosity (η) as D, τ ∝ η(p) with values of p = -0.88, -0.77, and +0.90, respectively. Spectral/solvation response functions (Sν(t)) are bimodal at all compositions, consisting of a subpicosecond fast component followed by a broadly distributed slower component extending over ps-ns times. Integral solvation times (⟨τ(solv)⟩ = ∫(0)(∞)Sν(t) dt) follow a power law on viscosity for mixturecompositions 0.2 ≤ x(IL) ≤ 1 with p = 0.79. With recent broad-band dielectric measurements [J. Phys. Chem. B 2012, 116, 7509] asinput, a simple dielectric continuum model provides predictions for solvation response functions that correctly capture thedistinctive bimodal character of the observed response. At x(IL) ∼ 1 predicted values of ⟨τ(solv)⟩ are smaller than those observed by a factor of 2-3, but the two become approximately equal at x(IL) = 0.2. Predictions of a recent semimolecular theory [J. Phys. Chem. B 2011, 115, 4011] are less accurate, being uniformly slower than the observed solvation dynamics.

  20. Continuous Crystallization of Urea-Water Mixture

    NASA Astrophysics Data System (ADS)

    Hokamura, Taku; Ohkubo, Hidetoshi; Watanabe, Satoshi; Seki, Mitsuo; Murakoshi, Hiromichi

    Ice slurries have been used as environmentally-friendly secondary refrigerants. In addition to such ice slurries, aqueous solutions in slurry-state have also been put to practical use at temperatures below 0 oC. Urea-water mixture is a multi-component substance that has a eutectic point. If we can form a two-phase fluid substance by the liquid-solid phases at the eutectic point, it can be used as a fluid latent heat storage material, which will maintain the secondary refrigerant in a heat exchanger at constant temperature. In the present study, we propose a urea-water mixture as a novel functional thermal fluid that can be used as a fluid latent heat material. To demonstrate its feasibility, we first measured the latent heat and density of a urea-water mixture, and then used a counter-flow double tube heat exchanger to produce a liquid-solid two-phase flow of the urea-water mixture. This work demonstrates that it is possible to make a fluid latent heat storage material continuously from an aqueous solution at the eutectic point by flowing it through a double tube heat exchanger equipped with a stirrer.

  1. Surface Tension Driven Instability Due to Internal Heat Sources in a Horizontal Layer of Binary Liquid Mixture

    NASA Astrophysics Data System (ADS)

    Takashima, Masaki; Mori, Kazuhiro

    1988-02-01

    Linear stability theory is applied to the problem of the onset of surface-tension-driven instability in a horizontal layer of binary liquid mixture confined at the bottom by a rigid, thermally insulating wall and at the top by a non-deformable free surface at which Newton’s cooling law is assumed to hold. It is also assumed that the liquid layer is heated by uniformly distributed internal heat sources which produce a nonlinear temperature profile and, in addition, a nonlinear concentration profile through the Soret effect. By neglecting small terms including the Soret coefficient ST, an eigenvalue system of eighth order is derived and is then solved exactly. For wide ranges of various parameters, the conditions under which instability sets in are determined numerically. As compared with the corresponding linear temperature case (M. Takashima: J. Phys. Soc. Jpn. 47 (1979) 1321; 49 (1980) 802), it is found that the nonlinear temperature profile produced by internal heat sources makes the liquid layer less stable for both stationary and oscillatory modes.

  2. Induced liquid-crystalline ordering in solutions of stiff and flexible amphiphilic macromolecules: Effect of mixture composition.

    PubMed

    Glagolev, Mikhail K; Vasilevskaya, Valentina V; Khokhlov, Alexei R

    2016-07-28

    Impact of mixture composition on self-organization in concentrated solutions of stiff helical and flexible macromolecules was studied by means of molecular dynamics simulation. The macromolecules were composed of identical amphiphilic monomer units but a fraction f of macromolecules had stiff helical backbones and the remaining chains were flexible. In poor solvents the compacted flexible macromolecules coexist with bundles or filament clusters from few intertwined stiff helical macromolecules. The increase of relative content f of helical macromolecules leads to increase of the length of helical clusters, to alignment of clusters with each other, and then to liquid-crystalline-like ordering along a single direction. The formation of filament clusters causes segregation of helical and flexible macromolecules and the alignment of the filaments induces effective liquid-like ordering of flexible macromolecules. A visual analysis and calculation of order parameter relaying the anisotropy of diffraction allow concluding that transition from disordered to liquid-crystalline state proceeds sharply at relatively low content of stiff components.

  3. Self-assembly of imidazolium-based surfactants in magnetic room-temperature ionic liquids: binary mixtures.

    PubMed

    Klee, Andreas; Prevost, Sylvain; Gradzielski, Michael

    2014-12-15

    The phase behaviour of binary mixtures of ionic surfactants (1-alkyl-3-imidazolium chloride, C(n)mimCl with n=14, 16 and 18) and imidazolium-based ionic liquids (1-alkyl-3-methylimidazolium tetrachloroferrate, C(n)mimFeCl4, with n=2 and 4) over a broad temperature range and the complete range of compositions is described. By using many complementary methods including differential scanning calorimetry (DSC), polarised microscopy, small-angle neutron and X-ray scattering (SANS/SAXS), and surface tension, the ability of this model system to support self-assembly is described quantitatively and this behaviour is compared with common water systems. The existence of micelles swollen by the solvent can be deduced from SANS experiments and represent a possible model for aggregates, which has barely been considered for ionic-liquid systems until now, and can be ascribed to the rather low solvophobicity of the surfactants. Our investigation shows that, in general, C(n)mimCl is a rather weak amphiphile in these ionic liquids. The amphiphilic strength increases systematically with the length of the alkyl chain, as seen from the phase behaviour, the critical micelle concentration, and also the level of definition of the aggregates formed.

  4. Induced liquid-crystalline ordering in solutions of stiff and flexible amphiphilic macromolecules: Effect of mixture composition

    NASA Astrophysics Data System (ADS)

    Glagolev, Mikhail K.; Vasilevskaya, Valentina V.; Khokhlov, Alexei R.

    2016-07-01

    Impact of mixture composition on self-organization in concentrated solutions of stiff helical and flexible macromolecules was studied by means of molecular dynamics simulation. The macromolecules were composed of identical amphiphilic monomer units but a fraction f of macromolecules had stiff helical backbones and the remaining chains were flexible. In poor solvents the compacted flexible macromolecules coexist with bundles or filament clusters from few intertwined stiff helical macromolecules. The increase of relative content f of helical macromolecules leads to increase of the length of helical clusters, to alignment of clusters with each other, and then to liquid-crystalline-like ordering along a single direction. The formation of filament clusters causes segregation of helical and flexible macromolecules and the alignment of the filaments induces effective liquid-like ordering of flexible macromolecules. A visual analysis and calculation of order parameter relaying the anisotropy of diffraction allow concluding that transition from disordered to liquid-crystalline state proceeds sharply at relatively low content of stiff components.

  5. Anomalous effective polarity of an air/liquid-mixture interface: a heterodyne-detected electronic and vibrational sum frequency generation study.

    PubMed

    Mondal, Sudip Kumar; Inoue, Ken-ichi; Yamaguchi, Shoichi; Tahara, Tahei

    2015-10-01

    We study the effective polarity of an air/liquid-mixture interface by using interface-selective heterodyne-detected electronic sum frequency generation (HD-ESFG) and vibrational sum frequency generation (HD-VSFG) spectroscopies. With water and N,N-dimethylformamide (DMF) chosen as two components of the liquid mixture, the bulk polarity of the mixture is controlled nearly arbitrarily by the mixing ratio. The effective polarity of the air/mixture interface is evaluated by HD-ESFG with a surface-active solvatochromic molecule used as a polarity indicator. Surprisingly, the interfacial effective polarity of the air/mixture interface increases significantly, when the bulk polarity of the mixture decreases (i.e. when the fraction of DMF increases). Judging from the hydrogen-bond structure at the air/mixture interface clarified by HD-VSFG, this anomalous change of the interfacial effective polarity is attributed to the interface-specific solvation structure around the indicator molecule at the air/mixture interface.

  6. Surface-slip equations for multicomponent nonequilibrium air flow

    NASA Technical Reports Server (NTRS)

    Gupta, R. N.; Scott, C. D.; Moss, J. N.

    1985-01-01

    Equations are presented for the surface-slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds number, high-altitude flight regime of a space vehicle. The equations are obtained from closed form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities were obtained in a form which can be employed in flowfield computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate, species-concentration boundary condition for a multicomponent mixture in absence of slip.

  7. Surface-slip equations for multicomponent, nonequilibrium air flow

    NASA Technical Reports Server (NTRS)

    Gupta, Roop N.; Scott, Carl D.; Moss, James N.; Goglia, Gene

    1985-01-01

    Equations are presented for the surface slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds-number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in absence of slip.

  8. Multicomponent Implant Releasing Dexamethasone

    NASA Astrophysics Data System (ADS)

    Nikkola, L.; Vapalahti, K.; Ashammakhi, N.

    2008-02-01

    Several inflammatory conditions are usually treated with corticosteroids. There are various problems like side effects with traditional applications of steroids, e.g. topical, or systemic routes. Local drug delivery systems have been studied and developed to gain more efficient administration with fewer side effects. Earlier, we reported on developing Dexamethasone (DX) releasing biodegradable fibers. However, their drug release properties were not satisfactory in terms of onset of drug release. Thus, we assessed the development of multicomponent (MC) implant to enhance earlier drug release from such biodegradable fibers. Poly (lactide-co-glycolide) (PLGA) and 2 wt-% and 8 wt-% DX were compounded and extruded with twin-screw extruder to form of fibers. Some of the fibers were sterilized to obtain a change in drug release properties. Four different fiber classes were studied: 2 wt-%, 8 wt-%, sterilized 2 wt-%, and sterilized 8 wt-%. 3×4 different DX-releasing fibers were then heat-pressed to form one multicomponent rod. Half of the rods where sterilized. Drug release was measured from initial fibers and multicomponent rods using a UV/VIS spectrometer. Shear strength and changes in viscosity were also measured. Drug release studies showed that drug release commenced earlier from multicomponent rods than from component fibers. Drug release from multicomponent rods lasted from day 30 to day 70. The release period of sterilized rods extended from day 23 to day 57. When compared to the original component fibers, the drug release from MC rods commenced earlier. The initial shear strength of MC rods was 135 MPa and decreased to 105 MPa during four weeks of immersion in phosphate buffer solution. Accordingly, heat pressing has a positive effect on drug release. After four weeks in hydrolysis, no disintegration was observed.

  9. Experimentally determined growth exponents during the late stage of spinodal demixing in binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Hobley, Jonathan; Kajimoto, Shinji; Takamizawa, Atsushi; Fukumura, Hiroshi

    2006-01-01

    Spinodal demixing was initiated in two systems, with critical and off-critical compositions, using nanosecond pulsed laser-induced temperature jumps (T-jumps) of various magnitude. In this way, deep quenches could be imposed on the systems. One system was the simple triethylamine (TEA)/water mixture and the other was the ionic mixture of 2-butoxyethanol (2BE)/water/KCl. The demixing process was followed using the technique of nanosecond time-resolved microscopic shadowgraphy. The growth of the evolving phase-separated domains followed a simple power law with respect to time in every case. For a given composition, the magnitude of the T-jump had little effect on the growth exponent, however the composition was found to influence the rate of domain growth. At off-critical mole fractions of 0.2 with respect to TEA, the domains grew according to the following expression: L(t)=t0.70 (where L(t)=the domain size) whereas at the critical TEA mole fraction of 0.08 the domains grew as L(t)=t0.52 . 2BE/water/KCl mixtures quenched at the just off-critical composition of 0.05mole fraction with respect to 2BE evolved as L(t)=t0.63 . These results will be compared to theoretical models and simulations and discussed in terms of estimated Reynolds numbers as well as the consumption and conversion of the available surface energy that fuels the demixing process.

  10. Luttinger liquid of polarons in one-dimensional boson-fermion mixtures.

    PubMed

    Mathey, L; Wang, D-W; Hofstetter, W; Lukin, M D; Demler, Eugene

    2004-09-17

    We use the bosonization approach to investigate quantum phases of boson-fermion mixtures (BFM) of atoms confined to one dimension by an anisotropic optical lattice. For a BFM with a single species of fermions we find a charge-density wave phase, a fermion pairing phase, and a phase separation regime. We also obtain the rich phase diagram of a BFM with two species of fermions. We demonstrate that these phase diagrams can be understood in terms of polarons, i.e., atoms "dressed" by screening clouds of the other atom species. Techniques to detect the resulting quantum phases are discussed.

  11. Theoretical rocket performance of JP-4 fuel with mixtures of liquid ozone and fluorine

    NASA Technical Reports Server (NTRS)

    Huff, Vearl N; Gordon, Sanford

    1957-01-01

    Data were estimated by means of a heat correction equation using data for JP-4 fuel with mixtures of oxygen and flourine. The estimated data were checked for several cases by direct calculations. The difference in specific impulse between the estimated and directly calculated values was from 0.2 to 0.8 pound-second per pound. The maximum value of specific impulse was 334.9 pound-seconds per pound for a combustion-chamber pressure of 600 pounds per square inch absolute and an exit pressure of 1 atmosphere.

  12. Viscosities of nonelectrolyte liquid mixtures. I. n-hexadecane + n-octane

    SciTech Connect

    Wakefield, D.L.; Marsh, K.N.

    1987-11-01

    Viscosities and densities of the n-alkanes, hexane, heptane, octane, nonane, decane, dodecane, tetradecane, hexadecane, and tetracosane, were measured for temperatures from 303 to 338 K. Viscosities were measured using a standard U-tube Ostwald viscometer; a pycnometer was used to measure both pure alkane and mixture densities. Results for the binary system n-hexadecane + n-octane at 318.16, 328.16, and 338.16 K are presented here, and comparisons with selected correlating equations are made.

  13. Pharmacokinetics screening for multi-components absorbed in the rat plasma after oral administration traditional Chinese medicine formula Yin-Chen-Hao-Tang by ultra performance liquid chromatography-electrospray ionization/quadrupole-time-of-flight mass spectrometry combined with pattern recognition methods.

    PubMed

    Wang, Xijun; Sun, Hui; Zhang, Aihua; Jiao, Guozheng; Sun, Wenjun; Yuan, Ye

    2011-12-01

    Traditional Chinese medicine (TCM) has been widely used in many oriental countries for thousands of years and played an indispensable role in the prevention and treatment of diseases, especially the complicated and chronic ones. It is a very complex mixture containing hundreds or thousands of different components. Pharmacokinetic study on active constituents in TCM preparations is a good way for us to explain and predict a variety of events related to the efficacy and toxicity of TCM. A selective and sensitive method of ultra performance liquid chromatography coupled with electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) was first developed to screen the potentially bioactive components in vivo, using the semi-quantitative determination of multicomponents in the rat plasma after a single oral administration of Yin-Chen-Hao-Tang (YCHT), a famous TCM formula for liver disorders. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were built to evaluate the differences of pharmacokinetic behaviors (time-course) of the absorbed components of YCHT. Here, we report that the developed method was successfully applied to monitoring the pharmacokinetic time-course of 21 compounds in rat plasma, and were grouped in 3 separate clusters using pattern recognition approaches (both HCA and PCA). Comparing the body dynamics of each composition, the initial choice of the following 9 compounds as the candidate components was: 7-methoxycoumarin-6-hydroxyl sulfate, genipingentiobioside, geniposide, 6,7-dimethylesculetin, peak 16, chimaphylin, 6-dementhoxycapillarisin, capillarisin, rhein. Pharmacokinetics based-UPLC-ESI-Q-TOF-MS/MS combined with HCA and PCA approaches can provide a reliable and suitable means of identifying and screening potentially bioactive components contributing to pharmacological effects of TCM, further prospecting natural products in the search for new leads in drug discovery.

  14. A classical model for closed-loop diagrams of binary liquid mixtures

    SciTech Connect

    Schnitzler, J.v.; Prausnitz, J.M. |

    1994-03-01

    A classical lattice model for closed-loop temperature-composition phase diagrams has been developed. It considers the effect of specific interactions, such as hydrogen bonding, between dissimilar components. This van Laar-type model includes a Flory-Huggins term for the excess entropy of mixing. It is applied to several liquid-liquid equilibria of nonelectrolytes, where the molecules of the two components differ in size. The model is able to represent the observed data semi-quantitatively, but in most cases it is not flexible enough to predict all parts of the closed loop quantitatively. The ability of the model to represent different binary systems is discussed. Finally, attention is given to a correction term, concerning the effect of concentration fluctuations near the upper critical solution temperature.

  15. Functionalized copolyimide membranes for the separation of gaseous and liquid mixtures

    PubMed Central

    Schmeling, Nadine; Konietzny, Roman; Sieffert, Daniel; Rölling, Patrick

    2010-01-01

    Summary Functionalized copolyimides continue to attract much attention as membrane materials because they can fulfill the demands for industrial applications. Thus not only good separation characteristics but also high temperature stability and chemical resistance are required. Furthermore, it is very important that membrane materials are resistant to plasticization since it has been shown that this phenomenon leads to a significant increase in permeability with a dramatic loss in selectivity. Plasticization effects occur with most polymer membranes at high CO2 concentrations and pressures, respectively. Plasticization effects are also observed with higher hydrocarbons such as propylene, propane, aromatics or sulfur containing aromatics. Unfortunately, these components are present in mixtures of high commercial relevance and can be separated economically by single membrane units or hybrid processes where conventional separation units are combined with membrane-based processes. In this paper the advantages of carboxy group containing 6FDA (4,4′-hexafluoroisopropylidene diphthalic anhydride) -copolyimides are discussed based on the experimental results for non cross-linked, ionically and covalently cross-linked membrane materials with respect to the separation of olefins/paraffins, e.g. propylene/propane, aromatic/aliphatic separation e.g. benzene/cyclohexane as well as high pressure gas separations, e.g. CO2/CH4 mixtures. In addition, opportunities for implementing the membrane units in conventional separation processes are discussed. PMID:20978620

  16. Structural and aggregate analyses of (Li salt + glyme) mixtures: the complex nature of solvate ionic liquids.

    PubMed

    Shimizu, Karina; Freitas, Adilson A; Atkin, Rob; Warr, Gregory G; FitzGerald, Paul A; Doi, Hiroyuki; Saito, Soshi; Ueno, Kazuhide; Umebayashi, Yasuhiro; Watanabe, Masayoshi; Canongia Lopes, José N

    2015-09-14

    The structure and interactions of different (Li salt + glyme) mixtures, namely equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide, nitrate or trifluoroacetate salts combined with either triglyme or tetraglyme molecules, are probed using Molecular Dynamics simulations. structure factor functions, calculated from the MD trajectories, confirmed the presence of different amounts of lithium-glyme solvates in the aforementioned systems. The MD results are corroborated by S(q) functions derived from diffraction and scattering data (HEXRD and SAXS/WAXS). The competition between the glyme molecules and the salt anions for the coordination to the lithium cations is quantified by comprehensive aggregate analyses. Lithium-glyme solvates are dominant in the lithium bis(trifluoromethylsulfonyl)imide systems and much less so in systems based on the other two salts. The aggregation studies also emphasize the existence of complex coordination patterns between the different species (cations, anions, glyme molecules) present in the studied fluid media. The analysis of such complex behavior is extended to the conformational landscape of the anions and glyme molecules and to the dynamics (solvate diffusion) of the bis(trifluoromethylsulfonyl)imide plus triglyme system.

  17. Structural and aggregate analyses of (Li salt + glyme) mixtures: the complex nature of solvate ionic liquids.

    PubMed

    Shimizu, Karina; Freitas, Adilson A; Atkin, Rob; Warr, Gregory G; FitzGerald, Paul A; Doi, Hiroyuki; Saito, Soshi; Ueno, Kazuhide; Umebayashi, Yasuhiro; Watanabe, Masayoshi; Canongia Lopes, José N

    2015-09-14

    The structure and interactions of different (Li salt + glyme) mixtures, namely equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide, nitrate or trifluoroacetate salts combined with either triglyme or tetraglyme molecules, are probed using Molecular Dynamics simulations. structure factor functions, calculated from the MD trajectories, confirmed the presence of different amounts of lithium-glyme solvates in the aforementioned systems. The MD results are corroborated by S(q) functions derived from diffraction and scattering data (HEXRD and SAXS/WAXS). The competition between the glyme molecules and the salt anions for the coordination to the lithium cations is quantified by comprehensive aggregate analyses. Lithium-glyme solvates are dominant in the lithium bis(trifluoromethylsulfonyl)imide systems and much less so in systems based on the other two salts. The aggregation studies also emphasize the existence of complex coordination patterns between the different species (cations, anions, glyme molecules) present in the studied fluid media. The analysis of such complex behavior is extended to the conformational landscape of the anions and glyme molecules and to the dynamics (solvate diffusion) of the bis(trifluoromethylsulfonyl)imide plus triglyme system. PMID:26245295

  18. New Critical Anomaly Induced in a Binary Liquid Mixture by a Selectively Adsorbing Wall

    NASA Astrophysics Data System (ADS)

    Franck, Carl; Schnatterly, S. E.

    1982-03-01

    The upper demixing critical point in carbon disulfide + nitromethane bounded by a crown glass surface which is expected to preferentially adsorb nitromethane has been studied. The σ-polarized reflectivity of the liquid/glass interface rises sharply with decreasing temperature above the bulk critical temperature. This effect cannot be explained as a purely bulk phenomenon, but agrees well with an approximate version of the critical wall-layer theory of de Gennes and Fisher.

  19. [Emission spectrum of liquid CO-N2 mixture at shock compression].

    PubMed

    Sun, Yue; Yi, Peng-Fei; Chen, Xian-Meng; Liu, Fu-Sheng; Zhang, Ming-Jian; Zheng, Xue-Ping; Xue, Xue-Dong

    2009-04-01

    Driving a copper projectile to impact a cryo-target made of aluminous alloy at the speed of 2.21 km x s(-1) with a two stage light gas gun, a proper one dimensional shockwave with a speed of 18.76 km x s(-1) was generated and directly acted on a uniform liquid in target, which was condensed by proportional gaseous carbon monoxide and nitrogen. At the measurement of Hugoniots, the full linear spectrum entirely dissociated with the plasma under the shock pressure of 33.5 GPa was caught by the use of intensified charge coupled device and accurate spectrographic technology. From the analysis of the spectrum, the authors know that the transient spectrograph with six channels can be used to measure and record the course of shock compression-irradiancy reliably, and the emitted spectral lines of shock compressed products indicated that the thermal dissociation and phase transition had occurred in homogeneous liquid of CO-N2. Furthermore, comparing the spectral intensity of lower central wavelength with that of higher, the fact of stronger intensity of 488 nm also validates that changes from "optic thin" to "optic thick" exist indeed in dense hydrocarbon liquid acted on by shock pressure.

  20. Dynamics of coarsening in multicomponent lipid vesicles with non-uniform mechanical properties

    NASA Astrophysics Data System (ADS)

    Funkhouser, Chloe M.; Solis, Francisco J.; Thornton, K.

    2014-04-01

    Multicomponent lipid vesicles are commonly used as a model system for the complex plasma membrane. One phenomenon that is studied using such model systems is phase separation. Vesicles composed of simple lipid mixtures can phase-separate into liquid-ordered and liquid-disordered phases, and since these phases can have different mechanical properties, this separation can lead to changes in the shape of the vesicle. In this work, we investigate the dynamics of phase separation in multicomponent lipid vesicles, using a model that couples composition to mechanical properties such as bending rigidity and spontaneous curvature. The model allows the vesicle surface to deform while conserving surface area and composition. For vesicles initialized as spheres, we study the effects of phase fraction and spontaneous curvature. We additionally initialize two systems with elongated, spheroidal shapes. Dynamic behavior is contrasted in systems where only one phase has a spontaneous curvature similar to the overall vesicle surface curvature and systems where the spontaneous curvatures of both phases are similar to the overall curvature. The bending energy contribution is typically found to slow the dynamics by stabilizing configurations with multiple domains. Such multiple-domain configurations are found more often in vesicles with spheroidal shapes than in nearly spherical vesicles.

  1. Nanophase segregation in binary mixtures of a bent-core and a rodlike liquid-crystal molecule.

    PubMed

    Zhu, Chenhui; Chen, Dong; Shen, Yongqiang; Jones, Christopher D; Glaser, Matthew A; Maclennan, Joseph E; Clark, Noel A

    2010-01-01

    We studied mixtures of the achiral bent-core mesogen NOBOW 1,3-phenylene bis[4-(4-9-alkoxyphenyliminonetyl)benzoates] (P-9-O-PIMB) and the small, rodlike liquid crystal 8CB using high-resolution synchrotron x-ray diffraction, freeze fracture transmission electron microscopy, and differential scanning calorimetry. NOBOW and 8CB mix in an isotropic state at high temperatures but phase separate at lower temperatures when NOBOW transforms into the B4 phase and forms chiral helical nanofilaments. In pure NOBOW, the nanofilaments are close packed but at moderate 8CB concentrations, they are separated by nanosized gaps filled by 8CB. At higher concentrations of 8CB, macroscopic phase separation occurs.

  2. Complex formation in liquid diethyl ether-chloroform mixtures examined by 2D correlation MID-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kutsyk, Andrii; Ilchenko, Oleksii; Pilgun, Yuriy; Obukhovsky, Vyacheslav; Nikonova, Viktoria

    2016-11-01

    Molecular complexes formation in diethyl ether-chloroform liquid solution is investigated by Mid-IR absorbance spectroscopy. The spectra were measured in spectral ranges of 1000-1550 cm-1 and 2650-3100 cm-1. 2D correlation analysis of spectral data indicates the presence of a third component in the solution. Excess spectroscopy shows that maximum of complex concentration is concentrated at around of 55% (vol.) of diethyl ether. 2D codistribution analysis supports such conclusion and provides the order of species distribution. Three-components MCR decomposition of spectral data was performed for the determination of concentration and spectral profiles of mixture components. Spectral transformations due to intermolecular interactions are in full agreement with those calculated according to density functional theory with B3LYP functional and cc-pVTz basis set for the case of equimolecular complex.

  3. Simultaneous calorimetric and polarization microscopy investigations of light induced changes over phase transitions in a liquid crystal-napthopyran mixture

    NASA Astrophysics Data System (ADS)

    Paoloni, S.; Mercuri, F.; Marinelli, M.; Pizzoferrato, R.; Zammit, U.; Kosa, T.; Sukhomlinova, L.; Taheri, B.

    2015-10-01

    We have studied the specific heat and the thermal conductivity in a 4-(n-octyl)-4'-cyanobiphenyl liquid crystal (LC)-photochromic molecules mixture, before, during, and after the photo-activation of the dispersed photochromic molecules, over both the smectic A-nematic and the nematic-isotropic phase transitions. The evaluation of the specific heat has enabled the determination of the changes of the phase transition characteristics induced by the photochromic molecules photoisomerization, while that of the thermal conductivity could be used to monitor the modifications induced in the average LC molecular orientation. The polarization microscopy imaging of the sample texture constituted a valuable support for the interpretation of the obtained thermal conductivity results.

  4. Determination of Stability from Multicomponent Pesticide Mixes.

    PubMed

    Dorweiler, Kelly J; Gurav, Jagdish N; Walbridge, James S; Ghatge, Vishwas S; Savant, Rahul H

    2016-08-10

    A study was conducted to evaluate the stability of 528 pesticides, metabolites, and contaminants prepared in large multicomponent mixes to enhance laboratory efficiency by allowing maximum use of the useful shelf life of the mixtures. Accelerated aging at 50 °C simulated 6 month, 1 year, and 2 year storage periods at -20 °C. Initial mixture composition was based on the instrument of analysis. After preliminary stability data had been obtained, mixtures were reformulated and re-evaluated. In all, 344 compounds showed satisfactory stability across all treatment groups, 100 compounds showed statistically significant changes between the control and the 6 month simulated storage period (27 with losses >20%), and the remainder showed borderline stability or were tested in one protocol. Stability behavior for organophosphates agreed with the proposed reaction mechanism responsible for acetylcholinesterase inhibition. A small number of compounds increased in response over time, suggesting the occurrence of degradation of precursor pesticides into these respective compounds.

  5. First-order character of the smectic-A to chiral nematic transition in chiral liquid-crystal mixtures.

    PubMed

    Jamée, P; Pitsi, G; Thoen, J

    2003-03-01

    An investigation into the smectic-A to chiral nematic (N'A) transition in liquid crystals is presented by using adiabatic scanning calorimetry (ASC). It is predicted theoretically that chirality drives this transition to first order. This transition is studied in mixtures of the nonchiral liquid crystal octyloxycyanobiphenyl (8OCB) and the chiral 4-(2-methylbutyl)-4(')-cyanobiphenyl (CB15), a system with a large (chiral) nematic region that widens upon increasing the chiral (CB15) fraction. An ASC measurement on pure 8OCB showed no evidence for a latent heat, in agreement with previous ac calorimetric studies, with an upper boundary for the latent heat (if any) of 1.8 J/kg. Since pure 8OCB has no measurable latent heat, and taking into account the widening of the chiral nematic region, the possibility of a continuous to first-order crossover due to the coupling of the nematic and the smectic order parameters, as occurring in several cases of smectic-A to nematic (NA) transitions, can be excluded. However, for all examined mixtures a latent heat could be determined at the smectic-A to chiral nematic transition. This confirms theoretical predictions of the first order character of this transition. Quantitatively, theoretical predictions of the evolution of the entropy discontinuities and latent heats of this transition were not consistent with the experimental results. It was further observed that the transition temperature decreases linearly in agreement with theoretical predictions and a previous ac calorimetric study. Finally, it was observed that the pretransitional specific heat capacity shows an interesting evolution upon increasing chiral fraction, and it may be concluded that any theoretical model based on Landau theory is not sufficient to describe this transition.

  6. A Temperature-Insensitive Cladding-Etched Fiber Bragg Grating Using a Liquid Mixture with a Negative Thermo-Optic Coefficient

    PubMed Central

    Kim, Kwang Taek; Kim, In Soo; Lee, Cherl-Hee; Lee, Jonghun

    2012-01-01

    To compensate for the temperature dependency of a standard FBG, a cladding-etched FBG immersed with a liquid mixture having a negative thermo-optic coefficient is presented, and its characteristics are investigated. The Bragg wavelength of the cladding-etched FBG is shifted counter to the direction of the Bragg wavelength shift of a conventional FBG according to the mixing ratio of glycerin to water; thus, the temperature-dependent Bragg wavelength shift was almost compensated by using a liquid mixture of water (50%) and glycerin (50%) having the negative thermo-optic coefficient of −5 × 10−4 °C−1. PMID:22969376

  7. Behavior of frustrated phase in ferroelectric and antiferroelectric liquid crystalline mixtures

    NASA Astrophysics Data System (ADS)

    Pociecha, D.; Glogarová, M.; Gorecka, E.; Mieczkowski, J.

    2000-06-01

    Binary mixtures of two successive homologues from a series of 4-(4'-alkoxy-biphenyl-4-yloxymethyl)benzoic acid 2-octanol esters exhibit a polar phase that differs from both ferroelectric (FE) and antiferroelectric (AF) phases, which exist in the pure compounds. When the concentration of the FE component is increased, this phase gradually changes its polar character from AF-like to FE-like, which is confirmed by the study of dielectric properties. Sample boundaries as well as the dc electric field introduce the FE phase, which remains stable after the field is switched off. Dielectric study confirms that this phase is composed of FE and AF clusters. The clusters arise due to frustration of FE and AF molecular order, which occurs as a result of the lowering of interlayer interactions.

  8. Fickian Diffusion Coefficient of Binary Liquid Mixtures in a Thermogravitational Column

    NASA Astrophysics Data System (ADS)

    Valencia, J. J.; Bou-Ali, M. M.; Platten, J. K.; Ecenarro, O.; Madariaga, J. M.; Santamaría, C. M.

    2007-09-01

    By measuring the mass fraction difference between the top and the bottom of a thermogravitational column as a function of time, we show that this transient evolution of the separation toward its steady value gives the isothermal mass diffusion coefficient, at least in the validity limit of the Furry-Jones-Onsager theory, whereas the final steady separation produces the thermodiffusion coefficient. The following mixtures have been considered: water-ethanol (39.12 wt% ethanol), toluene-hexane (51.7 wt% toluene), and the three systems of the so-called “benchmark of Fontainebleau”, which are the three binaries composed of isobutylbenzene and/or dodecane and/or 1,2,3,4 tetrahydronaphthalene (50 wt% in each component for each case). The obtained results indicate that reliable values of the isothermal diffusion coefficient can be determined by using the thermogravitational method.

  9. Ionic liquids and deep eutectic mixtures as new solvents for the synthesis of vanadium fluorides and oxyfluorides.

    PubMed

    Aidoudi, Farida H; Byrne, Peter J; Allan, Pheobe K; Teat, Simon J; Lightfoot, Philip; Morris, Russell E

    2011-04-28

    An exploratory study of the synthesis of vanadium (oxy)fluorides (VOFs) using ionic liquids (ILs) and deep eutectic mixtures (DESs) as a solvent yielded 10 different materials. The previously reported chain type: (NH(4))(2)VF(5) (1), (NH(4))(2)VOF(4) (2), NH(4)VO(3) (3) and (H(2)NH(2)(CH(2))(2)NH(2))VF(5) (9) have been successfully produced for the first time using ILs as the reaction media. The monomeric (HNH(2)CH(3))(2)VOF(4)(H(2)O) (4), the dimer (HNH(2)CH(3))(4)V(2)O(2)F(8) (5) and the 1D chains (HNH(2)CH(3))(2)VF(5) (6), (H(2)O)(2)VF(3) (7), α-(H(2)NH(2)(CH(2))(2)NH(2))VOF(4) (8) and β-(H(2)NH(2)(CH(2))(2)NH(2))VOF(4) (10) are novel materials. Template control has also been achieved by the selective choice of ILs or the appropriate deep eutectic mixture, where the expected template is delivered to the reaction by the partial breakdown of the urea derivative portion of the DES. PMID:21409203

  10. Frustration between syn- and anticlinicity in mixtures of chiral and non-chiral tilted smectic-C-type liquid crystals.

    PubMed

    Lagerwall, J P F; Heppke, G; Giesselmann, F

    2005-09-01

    We study the effects of mixing ferroelectric and antiferroelectric liquid-crystal compounds (FLCs and AFLCs) when the former are strictly synclinic and the latter strictly anticlinic, i.e. one mixture component exhibits only SmC* and the other only SmC(a)* as tilted phase. Three different paths between syn- and anticlinicity were detected: transition directly between SmC* and SmC(a)*, transition via the SmC(beta)* and SmC(gamma)* subphases, or by "escaping" the clinicity frustration by reducing the tilt to zero, i.e. the SmA* phase is extended downwards in temperature, separating SmC* from SmC(a)* in the phase diagram. The most common path is the one via the subphases, demonstrating that these phases appear as a result of frustration between syn- and anticlinic and, consequently, between syn- and antipolar order. For assessing the role of chirality, we also replaced the FLC with non-chiral synclinics. With one of the AFLCs, the route via supbhases was detected even in this case, suggesting that chirality--although necessary--does not have quite the importance that has previously been attributed to the appearance of the subphases. The path chosen in the mixture study seemed to be determined mainly by the synclinic component, the subphase induction occurring only when the SmA*-SmC* transition was second order.

  11. Coaxial probe and apparatus for measuring the dielectric spectra of high pressure liquids and supercritical fluid mixtures

    NASA Astrophysics Data System (ADS)

    Lee, Sung B.; Smith, Richard L.; Inomata, Hiroshi; Arai, Kunio

    2000-11-01

    A probe and apparatus were developed for measuring the dielectric spectra (complex permittivity) of high pressure liquids and supercritical fluid mixtures. The probe consisted a 2.2 mm semirigid coaxial cable that was cut off flat and mounted into a high pressure tube. The apparatus for measuring complex permittivity consisted of the dielectric probe, cell, densimeter, piston for varying the system density at constant composition, and magnetic pump for agitation and recirculation, all of which were housed in a constant temperature air bath. The probe is simple, robust, inexpensive, and further, its design allows for quick connection to high pressure systems. Probe accuracy is estimated to be ±0.5 in ɛ' and ±0.5 in ɛ″ from 200 MHz to 18 GHz based on replicate measurements of calibration and 2σ deviations over the interval. Dielectric spectra were measured over the 200 MHz-20 GHz range for methanol+carbon dioxide mixture at 323.2 K and a pressures up to 18 MPa.

  12. Hydrodynamic theories for mixtures of polymers and rodlike liquid crystalline polymers.

    PubMed

    Forest, M Gregory; Wang, Qi

    2005-10-01

    We develop a hydrodynamic theory for flows of incompressible blends of flexible polymers and rodlike nematic polymers (RNPs) or rodlike nematic liquid crystal polymers (RNLCPs) extending the thermodynamical theory of Muratov and E [J. Chem. Phys. 116, 4723 (2002)] for phase separation kinetics of the blend. We model the flexible polymer molecules in the polymer matrix as Rouse chains and assume the translational diffusion of the molecules is predominantly through the volume fraction of the flexible polymer and the molecules of rodlike nematic liquid crystal polymers. We then (i) derive the translational flux for the rodlike nematic liquid crystal polymers to ensure the incompressibility constraint; (ii) derive the elastic stress tensor, accounting for the contribution from both the rodlike nematic polymer and the flexible polymer matrix, as well as the extra elastic body force due to the nonlocal intermolecular potential for long range molecular interaction; (iii) show that the theory obeys positive entropy production and thereby satisfies the second law of thermodynamics. By applying the gradient expansion technique on the number density function of RNLCPs, we present an approximate, weakly nonlocal theory in differential form in which the intermolecular potential is given by gradients of the number density function of the RNLCP and the volume fraction of the flexible polymer. In the approximate theory, the elastic stress is augmented by an extra stress tensor due to the spatial convection of the macroscopic material point and long range interaction, whose divergence yields the analogous extra elastic body force with respect to the nonlocal intermolecular potential. Finally, we compare the model in steady simple shear with the Doi theory for bulk monodomains of rodlike nematic polymers.

  13. Hydrodynamic theories for mixtures of polymers and rodlike liquid crystalline polymers.

    PubMed

    Forest, M Gregory; Wang, Qi

    2005-10-01

    We develop a hydrodynamic theory for flows of incompressible blends of flexible polymers and rodlike nematic polymers (RNPs) or rodlike nematic liquid crystal polymers (RNLCPs) extending the thermodynamical theory of Muratov and E [J. Chem. Phys. 116, 4723 (2002)] for phase separation kinetics of the blend. We model the flexible polymer molecules in the polymer matrix as Rouse chains and assume the translational diffusion of the molecules is predominantly through the volume fraction of the flexible polymer and the molecules of rodlike nematic liquid crystal polymers. We then (i) derive the translational flux for the rodlike nematic liquid crystal polymers to ensure the incompressibility constraint; (ii) derive the elastic stress tensor, accounting for the contribution from both the rodlike nematic polymer and the flexible polymer matrix, as well as the extra elastic body force due to the nonlocal intermolecular potential for long range molecular interaction; (iii) show that the theory obeys positive entropy production and thereby satisfies the second law of thermodynamics. By applying the gradient expansion technique on the number density function of RNLCPs, we present an approximate, weakly nonlocal theory in differential form in which the intermolecular potential is given by gradients of the number density function of the RNLCP and the volume fraction of the flexible polymer. In the approximate theory, the elastic stress is augmented by an extra stress tensor due to the spatial convection of the macroscopic material point and long range interaction, whose divergence yields the analogous extra elastic body force with respect to the nonlocal intermolecular potential. Finally, we compare the model in steady simple shear with the Doi theory for bulk monodomains of rodlike nematic polymers. PMID:16383413

  14. Densities and vapor-liquid equilibria in binary mixtures formed by propyl methanoate + ethanol, + propan-1-ol, and + butan-1-ol at 160.0 kPa

    SciTech Connect

    Falcon, J.; Ortega, J.; Gonzalez, E.

    1996-07-01

    Densities and excess volumes were determined at 298.15 K for propyl methanoate + ethanol, + propan-1-ol, and + butan-1-ol. The results of those quantities were then correlated to get the concentrations of vapor-liquid equilibrium obtained isobarically at 160 kPa for the same mixtures. Two mixtures show azeotropes: for propyl methanoate (1) + ethanol (2), x{sub 1} = 0.443 at T = 358.7 K; and for propyl methanoate (1) + propan-1-ol (2), x{sub 1} = 0.762 at T = 368.2 K. The mixtures are thermodynamically consistent, and the predictions made using several group-contribution models are satisfactory.

  15. Natural remobilization of multicomponent DNAPL pools due to dissolution.

    PubMed

    Roy, J W; Smith, J E; Gillham, R W

    2002-12-01

    Mixtures of dense nonaqueous phase liquids (DNAPLs) trapped in the subsurface can act as long-term sources of contamination by dissolving into flowing groundwater. If the components have different solubilities then dissolution will alter the composition of the remaining DNAPL. We theorized that a multicomponent DNAPL pool may become mobile due to the natural dissolution process. In this study, we focused on two scenarios: (1) a DNAPL losing light component(s), with the potential for downward migration; and (2) a DNAPL losing dense component(s), with the potential for upward migration following transformation into a less dense than water nonaqueous phase liquid (LNAPL). We considered three binary mixtures of common groundwater contaminants: benzene and tetrachloroethylene (PCE), PCE and dichloromethane (DCM), and DCM and toluene. A number of physical properties that control the retention and transport of DNAPL in porous media were measured for the mixtures, namely: density, interfacial tension, effective solubility, and viscosity. All properties except density exhibited nonlinear relationships with changing molar ratio of the DNAPL. To illustrate the potential for natural remobilization, we modelled the following two primary mechanisms: the reduction in pool height as mass is lost by dissolution, and the changes in fluid properties with changing molar ratio of the DNAPL. The first mechanism always reduces the capillary pressure in the pool, while the second mechanism may increase the capillary pressure or alter the direction of the driving force. The difference between the rate of change of each determines whether the potential for remobilization increases or decreases. Static conditions and horizontal layering were assumed along with a one-dimensional, compositional modelling approach. Our results indicated that for initial benzene/PCE ratios greater than 25:75, the change in density was sufficiently faster than the decline in pool height to promote DNAPL

  16. Microscopic self-dynamics in liquid hydrogen and in its mixtures with deuterium

    SciTech Connect

    Colognesi, D.; Celli, M.; Zoppi, M.; Neumann, M.

    2004-12-01

    We have measured the dynamic structure factor of liquid parahydrogen, pure and mixed with deuterium, in various thermodynamic conditions using incoherent inelastic neutron scattering. The experiments were carried out on TOSCA-II, a new time-of-flight, inverse-geometry, crystal-analyzer spectrometer. After an accurate data reduction, the high-energy parts of the neutron spectra recorded in backward scattering were studied through the modified Young and Koppel model, from which the mean kinetic energy values for a hydrogen molecule were estimated. In addition the low-energy parts of the neutron spectra recorded in forward scattering were analyzed in the framework of the Gaussian approximation and fitted through a Levesque-Verlet model for the velocity autocorrelation function. Thus various physical quantities are determined and compared with accurate path integral Monte Carlo simulations. Despite the excellent quality of these fits, the velocity autocorrelation functions derived from the forward-scattering data appear totally unable to properly describe the backward-scattering ones. These findings prove an unquestionable breakdown of the Gaussian approximation in semiquantum liquids. The present results appear of great interest and suggest further investigation on the limits of the widely used Gaussian approximation.

  17. The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

    SciTech Connect

    Johnson, S.

    1999-02-12

    The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

  18. Multicomponent reactions of cyclobutanones.

    PubMed

    Pirrung, Michael C; Wang, Jianmei

    2009-04-17

    Cyclobutanones are essentially unknown as reactants in isonitrile-based multicomponent reactions. Ugi reactions of cyclobutanone and Passerini reactions of tetramethylcyclobutane-1,3-dione have been performed in this work. These reactions are significantly enhanced by being conducted in water, a subject of recent interest whose basis is still in question but whose effects are beyond doubt. The Ugi reaction of cyclobutanone has been used in a brief synthesis of an aspartame analogue.

  19. Immunoassays for the cancer biomarker CA125 based on a large-birefringence nematic liquid-crystal mixture

    PubMed Central

    Sun, Shih-Hung; Lee, Mon-Juan; Lee, Yun-Han; Lee, Wei; Song, Xiaolong; Chen, Chao-Yuan

    2014-01-01

    The use of fluorescence is ubiquitously found in the detection of immunoreaction; though with good sensitivity, this technique requires labeling as well as other time-consuming steps to perform the measurement. An alternative approach involving liquid crystals (LCs) was proposed, based on the fact that an immunocomplex can disturb the orientation of LCs, leading to an optical texture different from the case when only antigen or antibody exists. This method is label-free, easy to manipulate and low-cost. However, its sensitivity was low for practical usage. In this study, we adopted a high-birefringence liquid crystal (LC) to enhance the sensitivity for the immunodetection. Experiments were performed, targeting at the cancer biomarker CA125. We showed that the larger birefringence (Δn = 0.33 at 20 °C) amplifies the detected signal and, in turn, dramatically improves the detection limit. To avoid signal loss from conventional rinsing steps in immunodetection, CA125 antigen and antibody were reacted before immobilized on substrates. We studied the specific binding events and obtained a detection limit as low as 1 ng/ml. The valid temperature ranges were compared by using the typical single-compound LC 5CB and the high-birefringence LC mixture. We further investigated time dependency of the optical textures and affirmed the capability of LC-based immunodetection in distinguishing between specific and nonspecific antibodies. PMID:25657889

  20. Immunoassays for the cancer biomarker CA125 based on a large-birefringence nematic liquid-crystal mixture.

    PubMed

    Sun, Shih-Hung; Lee, Mon-Juan; Lee, Yun-Han; Lee, Wei; Song, Xiaolong; Chen, Chao-Yuan

    2015-01-01

    The use of fluorescence is ubiquitously found in the detection of immunoreaction; though with good sensitivity, this technique requires labeling as well as other time-consuming steps to perform the measurement. An alternative approach involving liquid crystals (LCs) was proposed, based on the fact that an immunocomplex can disturb the orientation of LCs, leading to an optical texture different from the case when only antigen or antibody exists. This method is label-free, easy to manipulate and low-cost. However, its sensitivity was low for practical usage. In this study, we adopted a high-birefringence liquid crystal (LC) to enhance the sensitivity for the immunodetection. Experiments were performed, targeting at the cancer biomarker CA125. We showed that the larger birefringence (Δn = 0.33 at 20 °C) amplifies the detected signal and, in turn, dramatically improves the detection limit. To avoid signal loss from conventional rinsing steps in immunodetection, CA125 antigen and antibody were reacted before immobilized on substrates. We studied the specific binding events and obtained a detection limit as low as 1 ng/ml. The valid temperature ranges were compared by using the typical single-compound LC 5CB and the high-birefringence LC mixture. We further investigated time dependency of the optical textures and affirmed the capability of LC-based immunodetection in distinguishing between specific and nonspecific antibodies. PMID:25657889

  1. Multicomponent MR Image Denoising

    PubMed Central

    Manjón, José V.; Thacker, Neil A.; Lull, Juan J.; Garcia-Martí, Gracian; Martí-Bonmatí, Luís; Robles, Montserrat

    2009-01-01

    Magnetic Resonance images are normally corrupted by random noise from the measurement process complicating the automatic feature extraction and analysis of clinical data. It is because of this reason that denoising methods have been traditionally applied to improve MR image quality. Many of these methods use the information of a single image without taking into consideration the intrinsic multicomponent nature of MR images. In this paper we propose a new filter to reduce random noise in multicomponent MR images by spatially averaging similar pixels using information from all available image components to perform the denoising process. The proposed algorithm also uses a local Principal Component Analysis decomposition as a postprocessing step to remove more noise by using information not only in the spatial domain but also in the intercomponent domain dealing in a higher noise reduction without significantly affecting the original image resolution. The proposed method has been compared with similar state-of-art methods over synthetic and real clinical multicomponent MR images showing an improved performance in all cases analyzed. PMID:19888431

  2. General Model for Multicomponent Ablation Thermochemistry

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Marschall, Jochen; Rasky, Daniel J. (Technical Monitor)

    1994-01-01

    A previous paper (AIAA 94-2042) presented equations and numerical procedures for modeling the thermochemical ablation and pyrolysis of thermal protection materials which contain multiple surface species. This work describes modifications and enhancements to the Multicomponent Ablation Thermochemistry (MAT) theory and code for application to the general case which includes surface area constraints, rate limited surface reactions, and non-thermochemical mass loss (failure). Detailed results and comparisons with data are presented for the Shuttle Orbiter reinforced carbon-carbon oxidation protection system which contains a mixture of sodium silicate (Na2SiO3), silica (SiO2), silicon carbide (SiC), and carbon (C).

  3. Calculation of multicomponent chemical equilibria in gas-solid-liquid systems: Calculation methods, thermochemical data, and applications to studies of high-temperature volcanic gases with examples from Mt. St. Helens

    SciTech Connect

    Symonds, R.B. ); Reed, M.H. )

    1993-10-01

    This paper documents the numerical formulations, thermochemical data base, and possible applications of computer programs, SOLVGAS and GASWORKS, for calculating multicomponent chemical equilibria in gas-solid-liquid systems. SOLVGAS and GASWORKS compute simultaneous equilibria by solving simultaneously a set of mass balance and mass action equations written for all gas species and for all gas-solid or gas-liquid equilibria. The programs interface with a thermo-chemical data base, GASTHERM, which contains coefficients for retrieval of the equilibrium constants from 25[degrees] to 1200[degrees]C. The programs and data base model dynamic chemical processes in 30- to 40-component volcanic-gas systems. The authors can model gas evaporation from magma, mixing of magmatic and hydrothermal gases, precipitation of minerals during pressure and temperature decrease, mixing of volcanic gas with air, and reaction of gases with wall rock. Examples are given of the gas-evaporation-from-magma and precipitation-with-cooling calculations for volcanic gases collected from Mt. St. Helens in September 1981. The authors predict: (1) the amounts of trace elements volatilized from shallow magma, deep magma, and wall rock, and (2) the solids that precipitate from the gas upon cooling. The predictions are tested by comparing them with the measured trace-element concentrations in gases and the observed sublimate sequence. This leads to the following conclusions: (1) most of the trace elements in the Mt. St. Helens gases are volatilized from shallow magma as simple chlorides; (2) some elements (for example, Al, Ca) exist dominantly in rock aerosols, not gases, in the gas stream; (3) near-surface cooling of the gases triggers precipitation of oxides, sulfides, halides, tungstates, and native elements; and (4) equilibrium cooling of the gases to 100[degrees]C causes most trace elements, except for Hg, Sb, and Se, to precipitate from the gas. 94 refs., 30 figs., 7 tabs.

  4. Multicomponent diffusion in two-temperature magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Ramshaw, J. D.; Chang, C. H.

    1996-06-01

    A recent hydrodynamic theory of multicomponent diffusion in multitemperature gas mixtures [J. D. Ramshaw, J. Non-Equilib. Thermodyn. 18, 121 (1993)] is generalized to include the velocity-dependent Lorentz force on charged species in a magnetic field B. This generalization is used to extend a previous treatment of ambipolar diffusion in two-temperature multicomponent plasmas [J. D. Ramshaw and C. H. Chang, Plasma Chem. Plasma Process. 13, 489 (1993)] to situations in which B and the electrical current density are nonzero. General expressions are thereby derived for the species diffusion fluxes, including thermal diffusion, in both single- and two-temperature multicomponent magnetohydrodynamics (MHD). It is shown that the usual zero-field form of the Stefan-Maxwell equations can be preserved in the presence of B by introducing generalized binary diffusion tensors dependent on B. A self-consistent effective binary diffusion approximation is presented that provides explicit approximate expressions for the diffusion fluxes. Simplifications due to the small electron mass are exploited to obtain an ideal MHD description in which the electron diffusion coefficients drop out, resistive effects vanish, and the electric field reduces to a particularly simple form. This description should be well suited for numerical calculations.

  5. Molecular theory of ferroelectric ordering in enantiomeric mixtures of smectic-C* liquid crystals.

    PubMed

    Osipov, M A; Guillon, D

    1999-12-01

    A molecular theory of ferroelectric ordering in smectic-C* liquid crystals composed of left and right enantiomers is developed taking into account the effects of chiral discrimination. The recently observed nonlinear dependence of the spontaneous polarization on the enantiomeric excess is explained in the framework of a molecular model that takes into consideration the strong electrostatic interaction between effective atomic charges in the chiral centers of the two enantiomers. This nonlinear dependence is determined by a difference of interaction energies between the pairs of chiral molecules with equal and opposite handedness, respectively. A relation between the molecular structure of different ferroelectric smectics C* and the dependence of the polarization on the enantiomeric excess is discussed in detail.

  6. Critical behavior at transitions from uniaxial to biaxial phases in a smectic liquid-crystal mixture.

    PubMed

    Sasaki, Y; Ema, K; Le, K V; Takezoe, H; Dhara, S; Sadashiva, B K

    2010-07-01

    We report results of calorimetric and optical investigations of binary mixtures of rodlike and bent-shaped molecules. We find that the observed critical heat anomaly associated with the smectic-A2 to biaxial smectic-A2b transition is well described with a Fisher-renormalized form of the usual scaling expression. The effect of renormalization is large in this system in part because of the moderately steep slope of the phase boundary (dT(c)/ dX∼100 K, where X is the mole fraction of the bent-core molecules) and in part because of the proximity to the tricritical point. The magnitude of heat anomaly at the smectic-A2-smectic-A2b transition showed a drastic decrease as X becomes smaller. Moreover, the nematic-smectic-A2 transitions investigated turned out to be always first order and the transition enthalpy showed only weak dependence on the concentration X. The results imply that the energy fluctuations around the smectic-A2-smectic-A2b transition are very sensitive to the underlying ordering of the smectic-A2 background.

  7. The inactivation of Chlorella spp. with dielectric barrier discharge in gas-liquid mixture

    NASA Astrophysics Data System (ADS)

    Song, Dan; Sun, Bing; Zhu, Xiaomei; Yan, Zhiyu; Liu, Hui; Liu, Yongjun

    2013-03-01

    The inactivation of Chlorella spp. with high voltage and frequency pulsed dielectric barrier discharge in hybrid gas-liquid reactor with a suspension electrode was studied experimentally. In the hybrid gas-liquid reactor, a steel plate was used as high voltage electrode while a quartz plate as a dielectric layer, another steel plate placing in the aqueous solution worked as a whole ground electrode. A suspension electrode is installed near the surface of solution between high voltage and ground electrode to make the dielectric barrier discharge uniform and stable, the discharge gap was between the quartz plate and the surface of the water. The effect of peak voltage, treatment time, the initial concentration of Chlorella spp. and conductivity of solution on the inactivation rate of Chlorella spp. was investigated, and the inactivation mechanism of Chlorella spp. preliminarily was studied. Utilizing this system inactivation of Chlorella spp., the inactivation rate increased with increasing of peak voltage, treatment time and electric conductivity. It was found that the inactivation rate of Chlorella spp. arrived at 100% when the initial concentration was 4 × 106 cells mL-1, and the optimum operation condition required a peak voltage of 20 kV, a treatment time of 10 min and a frequency of 7 kHz. Though the increasing of initial concentration of the Chlorella spp. contributed to the addition of interaction probability between the Chlorella spp. and O3, H2O2, high-energy electrons, UV radiation and other active substances, the total inactivation number raise, but the inactivation rate of the Chlorella spp. decreased.

  8. Mathematical simulation of gas-liquid mixture flow in a reservoir and a wellbore with allowance for the dynamical interactions in the reservoir-well system

    NASA Astrophysics Data System (ADS)

    Abbasov, E. M.; Feyzullayev, Kh. A.

    2016-01-01

    Fluid dynamic processes related to mature oil field development are simulated by applying a numerical algorithm based on the gas-liquid mixture flow equations in a reservoir and a wellbore with allowance for the dynamical interaction in the reservoir-well system. Numerical experiments are performed in which well production characteristics are determined from wellhead parameters.

  9. Dynamic equilibrium dissolution of complex nonaqueous phase liquid mixtures into the aqueous phase.

    PubMed

    Schluep, Mathias; Gälli, René; Imboden, Dieter M; Zeyer, Josef

    2002-07-01

    Human health risks posed by hazardous substances seeping from a pool of nonaqueous phase liquids (NAPLs) into groundwater change over time because the more soluble compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) dissolve faster into the aqueous phase than less soluble compounds such as polycyclic aromatic hydrocarbons (PAH). Long-term dissolution from diesel fuel into the aqueous phase was determined experimentally in a continuous flow-through system using the slow-stirring method. The data obtained are interpreted using a dynamic equilibrium dissolution model based on Raoult's law. The predicted temporal development of aqueous concentrations are in good agreement with the experimental results. When a compound in the NAPL approaches complete depletion, a tailing behavior is observed, which is assigned to nonequilibrium effects, such as mass transfer limitations in the NAPL phase. The model predicted an increase of the mean molar mass of the diesel fuel of 1.5% over the entire experimental period. It should be noted that, if the dissolution process were to proceed further, the change in the mean molar mass could become significant and render the simple model inaccurate. Yet the simple model supports the assessment of initial action after a contamination event as well as the planning of long-term remedial strategies. PMID:12109733

  10. Enhanced thermal energy harvesting performance of a cobalt redox couple in ionic liquid-solvent mixtures.

    PubMed

    Lazar, Manoj A; Al-Masri, Danah; MacFarlane, Douglas R; Pringle, Jennifer M

    2016-01-21

    Thermoelectrochemical cells are increasingly promising devices for harvesting waste heat, offering an alternative to the traditional semiconductor-based design. Advancement of these devices relies on new redox couple/electrolyte systems and an understanding of the interplay between the different factors that dictate device performance. The Seebeck coefficient (Se) of the redox couple in the electrolyte gives the potential difference achievable for a given temperature gradient across the device. Prior work has shown that a cobalt bipyridyl redox couple in ionic liquids (ILs) displays high Seebeck coefficients, but the thermoelectrochemical cell performance was limited by mass transport. Here we present the Se and thermoelectrochemical power generation performance of the cobalt couple in novel mixed IL/molecular solvent electrolyte systems. The highest power density of 880 mW m(-2), at a ΔT of 70 °C, was achieved with a 3 : 1 (v/v) MPN-[C2mim][B(CN)4] electrolyte combination. The significant power enhancement compared to the single solvent or IL systems results from a combination of superior ionic conductivity and higher diffusion coefficients, shown by electrochemical analysis of the different electrolytes. This is the highest power output achieved to-date for a thermoelectrochemical cell utilising a high boiling point redox electrolyte. PMID:26348719

  11. Dynamic equilibrium dissolution of complex nonaqueous phase liquid mixtures into the aqueous phase.

    PubMed

    Schluep, Mathias; Gälli, René; Imboden, Dieter M; Zeyer, Josef

    2002-07-01

    Human health risks posed by hazardous substances seeping from a pool of nonaqueous phase liquids (NAPLs) into groundwater change over time because the more soluble compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) dissolve faster into the aqueous phase than less soluble compounds such as polycyclic aromatic hydrocarbons (PAH). Long-term dissolution from diesel fuel into the aqueous phase was determined experimentally in a continuous flow-through system using the slow-stirring method. The data obtained are interpreted using a dynamic equilibrium dissolution model based on Raoult's law. The predicted temporal development of aqueous concentrations are in good agreement with the experimental results. When a compound in the NAPL approaches complete depletion, a tailing behavior is observed, which is assigned to nonequilibrium effects, such as mass transfer limitations in the NAPL phase. The model predicted an increase of the mean molar mass of the diesel fuel of 1.5% over the entire experimental period. It should be noted that, if the dissolution process were to proceed further, the change in the mean molar mass could become significant and render the simple model inaccurate. Yet the simple model supports the assessment of initial action after a contamination event as well as the planning of long-term remedial strategies.

  12. NMR investigation of imidazolium-based ionic liquids and their aqueous mixtures.

    PubMed

    Cesare Marincola, Flaminia; Piras, Cristina; Russina, Olga; Gontrani, Lorenzo; Saba, Giuseppe; Lai, Adolfo

    2012-04-10

    (1)H and (13)C NMR spectroscopy is employed to investigate the interaction of water with two imidazolium-based ionic liquids (ILs), 1-hexyl-3-methylimidazolium bromide ([C(6)mim]Br) and 1-octyl-3-methylimidazolium bromide ([C(8)mim]Br), at IL concentrations well above the critical aggregation concentration (CAC). The results are compared with those of the neat samples. To this aim, a detailed analysis of the changes in the (1)H chemical shifts, (13)C relaxation parameters, and 2D ROESY data due to the presence of water is performed. The results for both neat ILs are consistent with a packed structure where head-to-head, head-to-tail, and tail-to-tail contacts occur and where the site of maximal mobility restriction is at the polar head. At the lowest investigated water content, the presence of water influences mainly the environment around the IL polar head, slowing down the motional dynamics of the aromatic ring with respect to the alkyl chain. At higher water contents this difference diminishes, the motional freedom of the whole molecule increasing. The presence of ROESY cross-peaks between protons in the polar and apolar IL regions, as well as between protons in non-neighboring alkyl groups, at all investigated water contents suggests that the alkyl tails are not fully segregated in hydrophobic domains, as expected for micelle-like structures.

  13. Heat transfer and lethality considerations in aseptic processing of liquid/particle mixtures: a review.

    PubMed

    Ramaswamy, H S; Awuah, G B; Simpson, B K

    1997-04-01

    Consumer awareness and demand for nutritious yet inexpensive food products call for innovative processing techniques that have both safety and quality as primary objectives. These challenges appear to have been met by aseptic processing techniques, especially for liquid and high-acid foods. However, the extension of aseptic processing principles to low-acid foods containing discrete particles in viscous sauces has not been approved by regulatory agencies, particularly in North America. This apparent limitation is due primarily to the lack of adequate temperature monitoring devices to keep track of particles in dynamic motion, as well as to the residence time distribution of particles flowing in the continuous heat-hold-cool sections of the aseptic processing system. These problems have prompted active research to describe the phenomenal behavior of particulates through sound mathematical modeling and computer simulators. The accuracy of mathematical models depends heavily on how accurate input parametric values are. These parameters include the thermophysical properties of the carrier fluid and particles, as well as the aseptic processing system characteristics in relation to residence time distribution and the fluid-to-particle interfacial heat transfer coefficient. Apparently, several contradictory findings have been reported in the literature with respect to the effect of various processing parameters on the above-mentioned input parametric values. The need therefore arises for more collaborative studies involving the industry and academia. This review brings to perspective, the current status on the aseptic processing of particulate foods with respect to the critical processing parameters which affect the fluid-to-particle convective heat transfer coefficient associated with particulate laden products. PMID:9143820

  14. Raman study of potassium silicate glasses containing Rb +, Sr 2+, Y 3+ and Zr 4+: Implications for cation solution mechanisms in multicomponent silicate liquids

    NASA Astrophysics Data System (ADS)

    Ellison, Adam J. G.; Hess, Paul C.

    1994-04-01

    The parallel- and perpendicular-polarized Raman spectra of (1 - x)K 2O · xM 2/zz+O · 4SiO 2e glasses are presented, where M is one of the Period V cations Rb +, Sr 2+, Y 3+ or Zr 4+. These compositions represent the equal-oxygen substitution of a Period V cation for K +, which preserves the ratio of non-bridging oxygen (NBO) to Si atoms but not, in general, the ratio of all oxygen to all cations. Rb + and K + occupy very similar sites and appear to share the same NBO with virtually no energetic penalty. As the valence of the Period V cation increases, so does the tendency of the cation to form silicate species that are depolymerized relative to the species dominating the structure of the bulk glass. The tendency to form regions comparatively rich in Si-O-Si bonds increases in the same sense. The dominant silicate species are those with 0 or 1 NBO in all glasses. The spectra indicate that K+ shares NBO with Rb + or Sr 2+, that there is relatively little sharing of NBO by K + and Y 3+, and that K + and Zr 4+ share the same NBO in what appears to be a nearly fixed bulk stoichiometric K:Zr ratio of 2:1. The latter provides a mechanism for the substantial increase in ZrO 2 solubility seen in peralkaline liquids. A novel means of expressing homogeneous equilibria in silicate liquids is presented, whereby it is possible to make concrete predictions about the coordination numbers of cations in silicate liquids and to predict how they might be affected by the presence of other cations.

  15. Novel process and catalytic materials for converting CO2 and H2 containing mixtures to liquid fuels and chemicals.

    PubMed

    Meiri, Nora; Dinburg, Yakov; Amoyal, Meital; Koukouliev, Viatcheslav; Nehemya, Roxana Vidruk; Landau, Miron V; Herskowitz, Moti

    2015-01-01

    Carbon dioxide and water are renewable and the most abundant feedstocks for the production of chemicals and fungible fuels. However, the current technologies for production of hydrogen from water are not competitive. Therefore, reacting carbon dioxide with hydrogen is not economically viable in the near future. Other alternatives include natural gas, biogas or biomass for the production of carbon dioxide, hydrogen and carbon monoxide mixtures that react to yield chemicals and fungible fuels. The latter process requires a high performance catalyst that enhances the reverse water-gas-shift (RWGS) reaction and Fischer-Tropsch synthesis (FTS) to higher hydrocarbons combined with an optimal reactor system. Important aspects of a novel catalyst, based on a Fe spinel and three-reactor system developed for this purpose published in our recent paper and patent, were investigated in this study. Potassium was found to be a key promoter that improves the reaction rates of the RWGS and FTS and increases the selectivity of higher hydrocarbons while producing mostly olefins. It changed the texture of the catalyst, stabilized the Fe-Al-O spinel, thus preventing decomposition into Fe3O4 and Al2O3. Potassium also increased the content of Fe5C2 while shifting Fe in the oxide and carbide phases to a more reduced state. In addition, it increased the relative exposure of carbide iron on the catalysts surface, the CO2 adsorption and the adsorption strength. A detailed kinetic model of the RWGS, FTS and methanation reactions was developed for the Fe spinel catalyst based on extensive experimental data measured over a range of operating conditions. Significant oligomerization activity of the catalyst was found. Testing the pelletized catalyst with CO2, CO and H2 mixtures over a range of operating conditions demonstrated its high productivity to higher hydrocarbons. The composition of the liquid (C5+) was found to be a function of the potassium content and the composition of the feedstock

  16. Novel process and catalytic materials for converting CO2 and H2 containing mixtures to liquid fuels and chemicals.

    PubMed

    Meiri, Nora; Dinburg, Yakov; Amoyal, Meital; Koukouliev, Viatcheslav; Nehemya, Roxana Vidruk; Landau, Miron V; Herskowitz, Moti

    2015-01-01

    Carbon dioxide and water are renewable and the most abundant feedstocks for the production of chemicals and fungible fuels. However, the current technologies for production of hydrogen from water are not competitive. Therefore, reacting carbon dioxide with hydrogen is not economically viable in the near future. Other alternatives include natural gas, biogas or biomass for the production of carbon dioxide, hydrogen and carbon monoxide mixtures that react to yield chemicals and fungible fuels. The latter process requires a high performance catalyst that enhances the reverse water-gas-shift (RWGS) reaction and Fischer-Tropsch synthesis (FTS) to higher hydrocarbons combined with an optimal reactor system. Important aspects of a novel catalyst, based on a Fe spinel and three-reactor system developed for this purpose published in our recent paper and patent, were investigated in this study. Potassium was found to be a key promoter that improves the reaction rates of the RWGS and FTS and increases the selectivity of higher hydrocarbons while producing mostly olefins. It changed the texture of the catalyst, stabilized the Fe-Al-O spinel, thus preventing decomposition into Fe3O4 and Al2O3. Potassium also increased the content of Fe5C2 while shifting Fe in the oxide and carbide phases to a more reduced state. In addition, it increased the relative exposure of carbide iron on the catalysts surface, the CO2 adsorption and the adsorption strength. A detailed kinetic model of the RWGS, FTS and methanation reactions was developed for the Fe spinel catalyst based on extensive experimental data measured over a range of operating conditions. Significant oligomerization activity of the catalyst was found. Testing the pelletized catalyst with CO2, CO and H2 mixtures over a range of operating conditions demonstrated its high productivity to higher hydrocarbons. The composition of the liquid (C5+) was found to be a function of the potassium content and the composition of the feedstock.

  17. Influence of Trace Elements Mixture on Bacterial Diversity and Fermentation Characteristics of Liquid Diet Fermented with Probiotics under Air-Tight Condition

    PubMed Central

    Liu, Xiaolan; Wang, Chengwei; Lu, Wei

    2014-01-01

    Cu2+, Zn2+, Fe2+ and I− are often supplemented to the diet of suckling and early weaning piglets, but little information is available regarding the effects of different Cu2+, Zn2+, Fe2+ and I− mixtures on bacteria growth, diversity and fermentation characteristics of fermented liquid diet for piglets. Pyrosequencing was performed to investigate the effect of Cu2+, Zn2+, Fe2+ and I− mixtures on the diversity, growth and fermentation characteristics of bacteria in the liquid diet fermented with Bacillus subtilis and Enterococcus faecalis under air-tight condition. Results showed that the mixtures of Cu2+, Zn2+, Fe2+ and I− at different concentrations promoted Bacillus growth, increased bacterial diversity and lactic acid production and lowered pH to about 5. The importance of Cu2+, Zn2+, Fe2+ and I− is different for Bacillus growth with the order Zn2+> Fe2+>Cu2+> I− in a 21-d fermentation and Cu2+>I−>Fe2+>Zn2+ in a 42-d fermentation. Cu2+, Zn2+, Fe2+ and I− is recommended at a level of 150, 60, 150 and 0.6 mg/kg respectively for the production of fermented liquid diet with Bacillus subtilis. The findings improve our understanding of the influence of trace elements on liquid diet fermentation with probiotics and support the proper use of trace elements in the production of fermented liquid diet for piglets. PMID:25486254

  18. Influence of trace elements mixture on bacterial diversity and fermentation characteristics of liquid diet fermented with probiotics under air-tight condition.

    PubMed

    He, Yuyong; Chen, Zhiyu; Liu, Xiaolan; Wang, Chengwei; Lu, Wei

    2014-01-01

    Cu2+, Zn2+, Fe2+ and I- are often supplemented to the diet of suckling and early weaning piglets, but little information is available regarding the effects of different Cu2+, Zn2+, Fe2+ and I- mixtures on bacteria growth, diversity and fermentation characteristics of fermented liquid diet for piglets. Pyrosequencing was performed to investigate the effect of Cu2+, Zn2+, Fe2+ and I- mixtures on the diversity, growth and fermentation characteristics of bacteria in the liquid diet fermented with Bacillus subtilis and Enterococcus faecalis under air-tight condition. Results showed that the mixtures of Cu2+, Zn2+, Fe2+ and I- at different concentrations promoted Bacillus growth, increased bacterial diversity and lactic acid production and lowered pH to about 5. The importance of Cu2+, Zn2+, Fe2+ and I- is different for Bacillus growth with the order Zn2+> Fe2+>Cu2+> I- in a 21-d fermentation and Cu2+>I->Fe2+>Zn2+ in a 42-d fermentation. Cu2+, Zn2+, Fe2+ and I- is recommended at a level of 150, 60, 150 and 0.6 mg/kg respectively for the production of fermented liquid diet with Bacillus subtilis. The findings improve our understanding of the influence of trace elements on liquid diet fermentation with probiotics and support the proper use of trace elements in the production of fermented liquid diet for piglets. PMID:25486254

  19. Influence of trace elements mixture on bacterial diversity and fermentation characteristics of liquid diet fermented with probiotics under air-tight condition.

    PubMed

    He, Yuyong; Chen, Zhiyu; Liu, Xiaolan; Wang, Chengwei; Lu, Wei

    2014-01-01

    Cu2+, Zn2+, Fe2+ and I- are often supplemented to the diet of suckling and early weaning piglets, but little information is available regarding the effects of different Cu2+, Zn2+, Fe2+ and I- mixtures on bacteria growth, diversity and fermentation characteristics of fermented liquid diet for piglets. Pyrosequencing was performed to investigate the effect of Cu2+, Zn2+, Fe2+ and I- mixtures on the diversity, growth and fermentation characteristics of bacteria in the liquid diet fermented with Bacillus subtilis and Enterococcus faecalis under air-tight condition. Results showed that the mixtures of Cu2+, Zn2+, Fe2+ and I- at different concentrations promoted Bacillus growth, increased bacterial diversity and lactic acid production and lowered pH to about 5. The importance of Cu2+, Zn2+, Fe2+ and I- is different for Bacillus growth with the order Zn2+> Fe2+>Cu2+> I- in a 21-d fermentation and Cu2+>I->Fe2+>Zn2+ in a 42-d fermentation. Cu2+, Zn2+, Fe2+ and I- is recommended at a level of 150, 60, 150 and 0.6 mg/kg respectively for the production of fermented liquid diet with Bacillus subtilis. The findings improve our understanding of the influence of trace elements on liquid diet fermentation with probiotics and support the proper use of trace elements in the production of fermented liquid diet for piglets.

  20. Multicomponent nucleation and droplet growth in natural gas

    NASA Astrophysics Data System (ADS)

    Luijten, C. C. M.; van Hooy, R. G. P.; Janssen, J. W. F.; van Dongen, M. E. H.

    1998-09-01

    The first quantitative experimental results are presented on homogeneous nucleation and droplet growth in a multicomponent gas-vapor mixture. Using the pulse-expansion wave tube technique, we investigated the condensation behavior of natural gas consisting of over 30 components. Data were obtained in the pressure range between 6 and 24 bar and at temperatures ranging from 221 to 237 K. The observed droplet growth rates are quantitatively explained using a multicomponent model for diffusion controlled growth. The nucleation rate data are for the moment mainly presented as a challenge to theoreticians, although some qualitative arguments are presented that could be helpful in the interpretation. The data appear to agree at least qualitatively with theoretical values (according to the revised binary classical nucleation theory) for a mixture of n-octane and methane, a model mixture which also shows the same macroscopic phase behavior as natural gas.

  1. Improvement of the relaxation time and the order parameter of nematic liquid crystal using a hybrid alignment mixture of carbon nanotube and polyimide

    SciTech Connect

    Lee, Hyojin; Yang, Seungbin; Lee, Ji-Hoon; Soo Park, Young

    2014-05-12

    We examined the electrooptical properties of a nematic liquid crystal (LC) sample whose substrates were coated with a mixture of carbon nanotube (CNT) and polyimide (PI). The relaxation time of the sample coated with 1.5 wt. % CNT mixture was about 35% reduced compared to the pure polyimide sample. The elastic constant and the order parameter of the CNT-mixture sample were increased and the fast relaxation of LC could be approximated to the mean-field theory. We found the CNT-mixed polyimide formed more smooth surface than the pure PI from atomic force microscopy images, indicating the increased order parameter is related to the smooth surface topology of the CNT-polyimide mixture.

  2. Electrohydrodynamics Of Multicomponent Vesicles

    NASA Astrophysics Data System (ADS)

    Gera, Prerna; Salac, David

    2015-11-01

    The addition of cholesterol into a lipid membrane induces the formation of distinct domains. These domains try to minimize the overall energy of the system by coalescence and migration. The application of electric fields will induce flow of these membrane domains and influence the rate at which they coarsen. In this work the electrohydrodynamics of multicomponent vesicles is numerically modelled. The method uses a Cahn-Hilliard-Cook model of the lipid domains restricted to a deforming three-dimensional vesicle and will be briefly discussed. Sample results will be presented and compared to experimental observations. This work supported by NSF Grant #1253739.

  3. Effect of oil droplets and their solid/liquid composition on the phase separation of protein-polysaccharide mixtures.

    PubMed

    Hanazawa, Tomohito; Murray, Brent S

    2013-08-01

    The phase separation of a model system consisting of sodium caseinate + xanthan ± a low fraction (up to 3 wt %) of an oil-in-water emulsion was studied at room temperature (20-25 °C). The composition of the oil phase was either 100 wt % n-tetradecane (TD); 50% TD + 50% eicosane (EC) or 100% EC. The droplets in these three "emulsions" were therefore totally liquid, partially solid, and totally solid, respectively. In the presence of 22 mM CaCl2, the mixed TD+EC droplets were most effective at inhibiting phase separation, while the EC emulsions could not prevent phase separation at all. At 32 mM CaCl2 the emulsions tended to promote phase separation, possibly due to enhanced calcium ion-induced droplet aggregation. The apparent interfacial viscosity (ηi) between two macroscopically separated phases was also measured. In the presence of the semisolid mixed droplets ηi = 25 mN s m(-1), significantly higher than ηi with the pure (liquid) TD droplets (15 mN s m(-1)) or with the pure solid EC droplets (12 mN s m(-1)) or in the absence of droplets (<3 mN s m(-1)). Confocal microscopy showed that the microstructure of the phase separating regions also depended upon the composition of the oil droplets, and it is tentatively suggested that the more marked effects of the mixed emulsion droplets were due to them forming a stronger network at the interface via partial coalescence. Control of the extent of interfacial aggregation of droplets is therefore possibly one way to influence the course of phase separation in biopolymer mixtures. PMID:23805874

  4. Study of the isotropic to smectic-A phase transition in liquid crystal and acetone binary mixtures.

    PubMed

    Sigdel, Krishna P; Iannacchione, Germano S

    2010-11-01

    The first-order transition from the isotropic (I) to smectic-A (Sm A) phase in the liquid crystal 4-cyano-4(')-decylbiphenyl (10CB) doped with the polar solvent acetone (ace) has been studied as a function of solvent concentration by high-resolution ac-calorimetry. Heating and cooling scans were performed for miscible 10CB+ace samples having acetone mole fractions from x(ace)=0.05 (1 wt %) to 0.36 (10%) over a wide temperature range from 310 to 327 K. Two distinct first-order phase transition features are observed in the mixture whereas there is only one transition (I-Sm A) in the pure 10CB for that particular temperature range. Both calorimetric features reproduce on repeated heating and cooling scans and evolve with increasing x(ace) with the high-temperature feature relatively stable in temperature but reduced in size while the low-temperature feature shifts dramatically to lower temperature and exhibits increased dispersion. The coexistence region increases for the low-temperature feature but remains fairly constant for the high-temperature feature as a function of x(ace). Polarizing optical microscopy supports the identification of a smectic phase below the high-temperature heat capacity signature indicating that the low-temperature feature represents an injected smectic-smectic phase transition. These effects may be the consequence of screening the intermolecular potential of the liquid crystals by the solvent that stabilizes a weak smectic phase intermediate of the isotropic and pure smectic-A.

  5. Mechanics of Turbulence of Multicomponent Gases

    NASA Astrophysics Data System (ADS)

    Marov, Mikhail Ya.; Kolesnichenko, Aleksander V.

    2002-02-01

    Turbulence in multicomponent reacting gas mixtures is an important mechanism underlying numerous natural phenomena closely related to the study of our space environment. This book develops a new mathematical approach for modelling multicomponent gas turbulence that adequately describes the combined processes of dynamics and heat and mass transfer when chemical kinetics and turbulent mixing are equally important. The developed models include the evolutionary transfer equations for the single-point second correlation moments of turbulent fluctuations of thermohydrodynamical parameters. The phenomenological approach to the closure problem in hydrodynamic equations of mean motion at the level of the first order moments is based on the thermodynamics of irreversible processes and enables defining relationships in a more general form as compared to those conventionally deduced using the mixing path concept. Based on the developed approach, turbulent exchange factors for a planetary upper atmosphere are evaluated, and a turbulent model of a protoplanetary accretion gas-dust disk involving heat and mass transfer and coagulation is also considered. As compared to previously published books on the problem of turbulence, this book deals, for the first time, with the complicated models of reacting gas mixtures. It is intended for graduate and postgraduate students in the fields of fluid gas dynamics, astrophysics, space physics, planetary sciences, and aeronomy, and especially for those dealing with computer modelling of the processes in such natural media. The book may also be of interest to specialists in the relevant fields of ecology, engineering, and material processing.

  6. Schiff base ligands and their transition metal complexes in the mixtures of ionic liquid + organic solvent: a thermodynamic study.

    PubMed

    Shekaari, Hemayat; Kazempour, Amir; Khoshalhan, Maryam

    2015-01-21

    Schiff bases and their metal complexes in the mixtures of ionic liquid (IL) + organic solvent have shown great potential in attractive oxidation catalytic processes. The efficiency of such a process is strongly dependent on the various molecular interactions occurring between components. Thermodynamic properties of these systems can provide valuable information about structural interactions. Therefore, in this work, the interactions of the IL 1-hexyl-3-methylimidazolium chloride ([HMIm]Cl) with Schiff bases in organic solvents were studied through the measurements of density, viscosity, and electrical conductivity. The effect of solvent on the interactions was examined by the solutions of IL + BPIC Schiff base + solvent (C2H6O-C3H8O-C4H10O). Moreover, the influence of Schiff base ligand and Schiff base complex structures was probed by the solutions of IL + DMA + ligand (salcn/salpr/salen) and IL + DMA + complex (VO(3-OMe-salen)/VO(salophen)/VO(salen)), respectively. Using the experimental data, some important thermodynamic properties, such as standard partial molar volume (V(0)(φ,IL)), experimental slope (Sv), viscosity B-coefficient, solvation number (B/V(0)(φ,IL) and limiting molar conductivity (Λ0) were calculated and discussed in terms of solute-solvent (IL-DMF/alcohol) and solute-cosolute (IL-Schiff base) interactions.

  7. Influence of Electric Fields on the Flow of a Liquid Crystal Mixture in Circular-Pipe Electrodes

    NASA Astrophysics Data System (ADS)

    Tsukiji, Tetsuhiro; Koyabu, Eitaro; Tsuji, Tomohiro; Chono, Shigeomi

    Two types of circular-pipe electrode are designed to control the pressure and flow rate of electrorheological(ER) fluids under the application of an electric field. The shape of the electrode is a circular pipe and some parts of the inner surface of the pipe are made of electrode strips. A liquid crystal mixture is selected as a homogeneous ER fluid and the pressure drop in the circular-pipe electrode is measured at constant flow rates. On the other hand, numerical analysis of the electric field and the fluid flow in the circular-pipe electrode is conducted. It is assumed that the viscosity, which depends on the electric field intensity, is distributed in the flow fields. The relationships between the flow rate and the pressure are simulated numerically for various electric field intensities, which agree with experimental results. The difference in the ER effect between the two types of electrodes is discussed on the basis of the distributions of the electric field intensity and the pressure drop. Furthermore, the influence of both the number of electrode strips and the gaps between electrode strips in the pipe on the flow rate vs. pressure characteristics is investigated numerically, and a comparison of the flow characteristics between the present electrodes and two types of parallel-plate electrodes is conducted.

  8. Molecular interactions in the ionic liquid emim acetate and water binary mixtures probed via NMR spin relaxation and exchange spectroscopy.

    PubMed

    Allen, Jesse J; Bowser, Sage R; Damodaran, Krishnan

    2014-05-01

    Interactions of ionic liquids (ILs) with water are of great interest for many potential IL applications. 1-Ethyl-3-methylimidazolium (emim) acetate, in particular, has shown interesting interactions with water including hydrogen bonding and even chemical exchange. Previous studies have shown the unusual behavior of emim acetate when in the presence of 0.43 mole fraction of water, and a combination of NMR techniques is used herein to investigate the emim acetate-water system and the unusual behavior at 0.43 mole fraction of water. NMR relaxometry techniques are used to describe the effects of water on the molecular motion and interactions of emim acetate with water. A discontinuity is seen in nuclear relaxation behavior at the concentration of 0.43 mole fraction of water, and this is attributed to the formation of a hydrogen bonded network. EXSY measurements are used to determine the exchange rates between the H2 emim proton and water, which show a complex dependence on the concentration of the mixture. The findings support and expand our previous results, which suggested the presence of an extended hydrogen bonding network in the emim acetate-water system at concentrations close to 0.50 mole fraction of H2O. PMID:24654003

  9. Simultaneous determination of acetaminophen, guaifenesin, pseudoephedrine, pholcodine, and paraben preservatives in cough mixture by high-performance liquid chromatography.

    PubMed

    Carnevale, L

    1983-02-01

    The separation and simultaneous determination, by high-performance liquid chromatography, of acetaminophen (I), guaifenesin (II), pseudoephedrine hydrochloride (III), and pholcodine (IV), together with a series of parabens (methyl to butyl, V-VIII) in a cough mixture, has been demonstrated using a chemically bonded octadecylsilane stationary phase with a mobile phase of methanol-water-acetic acid (45:55:2) containing the ion-pairing agent octanesulfonic acid. Retention volumes for the active ingredients were 3.8 ml, 5.4 ml, 9.4 ml, and 15.6 ml for compounds I-IV, respectively. Corrected retention volumes for the parabens [5.4 ml for methyl (V), 9.6 ml for ethyl (VI), 18.5 ml for propyl (VII), and 37.9 ml for butyl (VIII)] showed an exponential relationship with chain length of the esterifying alcohols. Excipients did not interfere with the estimation of any of the compounds, hence pretreatment of the sample was unnecessary. Average recoveries of the active ingredients and of the parabens from laboratory prepared samples were essentially 100% of theoretical with standard deviations of 1.7, 0.3, 1.5, 0.3, 0.3, 3.3, 0.7, and 2.7% for I-VIII, respectively. PMID:6834261

  10. Simultaneous determination of acetaminophen, guaifenesin, pseudoephedrine, pholcodine, and paraben preservatives in cough mixture by high-performance liquid chromatography.

    PubMed

    Carnevale, L

    1983-02-01

    The separation and simultaneous determination, by high-performance liquid chromatography, of acetaminophen (I), guaifenesin (II), pseudoephedrine hydrochloride (III), and pholcodine (IV), together with a series of parabens (methyl to butyl, V-VIII) in a cough mixture, has been demonstrated using a chemically bonded octadecylsilane stationary phase with a mobile phase of methanol-water-acetic acid (45:55:2) containing the ion-pairing agent octanesulfonic acid. Retention volumes for the active ingredients were 3.8 ml, 5.4 ml, 9.4 ml, and 15.6 ml for compounds I-IV, respectively. Corrected retention volumes for the parabens [5.4 ml for methyl (V), 9.6 ml for ethyl (VI), 18.5 ml for propyl (VII), and 37.9 ml for butyl (VIII)] showed an exponential relationship with chain length of the esterifying alcohols. Excipients did not interfere with the estimation of any of the compounds, hence pretreatment of the sample was unnecessary. Average recoveries of the active ingredients and of the parabens from laboratory prepared samples were essentially 100% of theoretical with standard deviations of 1.7, 0.3, 1.5, 0.3, 0.3, 3.3, 0.7, and 2.7% for I-VIII, respectively.

  11. Liquid gallium-lead mixture phase diagram, surface tension near the critical mixing point, and prewetting transition.

    PubMed

    Osman, S M; Grosdidier, B; Ali, I; Abdellah, A Ben

    2013-06-01

    Quite recently, we reported a semianalytical equation of state (EOS) for the Ga-Pb alloy [Phys. Rev. B 78, 024205 (2008)], which was based on the first-order perturbation theory of fluid mixtures, within the simplified random phase approximation, in conjunction with the Grosdidier et al. model pair potentials for Ga-Ga and Pb-Pb with a suitable nonadditive pair potential between Ga-Pb unlike pairs. In the present work, we employ the present EOS to calculate the Ga-Pb phase diagram along the immiscibility gap region. The accuracy of the EOS is tested by consulting the empirical binodal curve. A statistical-mechanical-based theory for the surface tension is employed to obtain an analytical expression for the alloy surface tension. We calculated the surface tension along the bimodal curve and at extreme conditions of temperatures and pressures. The surface tension exhibits reasonably well the prewetting transition of Pb atoms at the surface of the Ga-rich liquid alloy and could qualitatively explain the prewetting phenomena occurring in the Ga-rich side of the phase diagram. The predicted prewetting line and wetting temperature qualitatively agree with the empirical measurements.

  12. Diverging Thermodynamic Derivatives Associated with Heterogeneous Chemical Equilibrium in a Binary Liquid Mixture with a Consolute Point

    NASA Astrophysics Data System (ADS)

    Hu, B.; Baird, J. K.; Alvarez, P. K.; Melton, K. C.; Barlow, D. A.; Richey, R. D.

    2014-05-01

    The solubilities of tin(II) oxide, copper(II) oxide, and cobalt(II) oxide have been determined in the liquid mixture, isobutyric acid + water, along the critical isopleth. When plotted in van't Hoff form with versus , the solubility measurements, , lie on a straight line for values of the temperature, , which are sufficiently in excess of the critical solution temperature, In the case of SnO, the dissolution reaction is exothermic, and the slope of the van't Hoff plot diverges toward positive infinity as In the case of both CuO and CoO, the dissolution reaction is endothermic, and the slope of the van't Hoff plot diverges toward negative infinity as Analysis of these ternary, heterogeneous equilibria using finite dimensional vector space stoichiometry theory shows that each contains two linearly independent components. According to the Gibbs phase rule, two-phase equilibria of this type can be described by two fixed, intensive variables, which are accounted for by the temperature and the pressure, respectively. The Gibbs-Helmholtz equation and the principle of critical-point universality can be combined to predict under conditions of fixed temperature and pressure that when dissolution is exothermic, should diverge toward positive infinity in the critical region, while when dissolution is endothermic, should diverge toward negative infinity. Our experiments include examples confirming both these predictions.

  13. Order of phase transitions and tricriticality in mixtures of octyloxycyanobiphenyl and nonyloxycyanobiphenyl liquid crystals: a high-resolution study by adiabatic scanning calorimetry.

    PubMed

    Cordoyiannis, George; Tripathi, Chandra Shekhar Pati; Glorieux, Christ; Thoen, Jan

    2010-09-01

    A detailed study has been performed for mixtures of octyloxycyanobiphenyl (8OCB) and nonyloxycyanobiphenyl (9OCB) liquid crystals and nine of their mixtures by means of high-resolution adiabatic scanning calorimetry. The isotropic to nematic transitions are weakly first order with latent heat values in the range usually encountered for this transition in other liquid crystals. With the exception of pure 8OCB, for which only an upper limit of 1.8 J  kg(-1) for the latent heat could be established, finite latent heats have been obtained for the nematic to smectic-A transition of all the mixtures and of pure 9OCB. The concentration dependence of their latent heats could be well fitted with a crossover function consistent with a mean-field free-energy expression that has a nonzero cubic term induced by the Halperin-Lubensky-Ma (HLM) coupling between the smectic-A order parameter and the orientational director fluctuations. Clearly first-order transitions with measurable latent heats are found for mole fractions of 9OCB in the mixtures where the effective critical exponent for the specific-heat capacity has substantially lower values than the tricritical one (0.5). This is qualitatively different from what has been observed so far in other liquid-crystal systems and yields strong experimental evidence from a calorimetric experiment for the HLM coupling between the smectic-A order parameter and the director orientation fluctuations.

  14. Modeling of multiphase transport of multicomponent organic contaminants and heat in the subsurface: Numerical model formulation

    NASA Astrophysics Data System (ADS)

    Adenekan, A. E.; Patzek, T. W.; Pruess, K.

    1993-11-01

    A numerical compositional simulator (Multiphase Multicomponent Nonisothermal Organics Transport Simulator (M2NOTS)) has been developed for modeling transient, three-dimensional, nonisothermal, and multiphase transport of multicomponent organic contaminants in the subsurface. The governing equations include (1) advection of all three phases in response to pressure, capillary, and gravity forces; (2) interphase mass transfer that allows every component to partition into each phase present; (3) diffusion; and (4) transport of sensible and latent heat energy. Two other features distinguish M2NOTS from other simulators reported in the groundwater literature: (1) the simulator allows for any number of chemical components and every component is allowed to partition into all fluid phases present, and (2) each phase is allowed to completely disappear from, or appear in, any region of the domain during a simulation. These features are required to model realistic field problems involving transport of mixtures of nonaqueous phase liquid contaminants, and to quantify performance of existing and emerging remediation methods such as vacuum extraction and steam injection.

  15. To Polarize or Not to Polarize? Charge-on-Spring versus KBFF Models for Water and Methanol Bulk and Vapor-Liquid Interfacial Mixtures.

    PubMed

    Ploetz, Elizabeth A; Rustenburg, Ariën S; Geerke, Daan P; Smith, Paul E

    2016-05-10

    Simulations of water and methanol mixtures using polarizable force fields (FFs) for methanol (COS/M and CPC) and water (COS/G2) were performed and compared to experiment and also to a nonpolarizable methanol (KBFF) model with SPC/E water in an effort to quantify the importance of explicit electronic polarization effects in bulk liquid mixtures and vapor-liquid interfaces. The bulk liquid mixture properties studied included the center of mass radial distribution functions, Kirkwood-Buff integrals (KBIs), volumetric properties, isothermal compressibility, enthalpy of mixing, dielectric constant, and diffusion coefficients. The vapor-liquid interface properties investigated included the relative surface probability distributions, surface tension, excess surface adsorption, preferred surface molecule orientations, and the surface dipole. None of the three FFs tested here was clearly superior for all of the properties examined. All the force fields typically reproduced the correct trends with composition for both the bulk and interfacial system properties; the differences between the force fields were primarily quantitative. The overall results suggest that the polarizable FFs are not, at the present stage of development, inherently better able to reproduce the studied bulk and interfacial properties-despite the added degree of explicit transferability that is, by definition, built into the polarizable models. Indeed, the specific parametrization of the FF appears to be just as important as the class of FF. PMID:27045390

  16. To Polarize or Not to Polarize? Charge-on-Spring versus KBFF Models for Water and Methanol Bulk and Vapor-Liquid Interfacial Mixtures.

    PubMed

    Ploetz, Elizabeth A; Rustenburg, Ariën S; Geerke, Daan P; Smith, Paul E

    2016-05-10

    Simulations of water and methanol mixtures using polarizable force fields (FFs) for methanol (COS/M and CPC) and water (COS/G2) were performed and compared to experiment and also to a nonpolarizable methanol (KBFF) model with SPC/E water in an effort to quantify the importance of explicit electronic polarization effects in bulk liquid mixtures and vapor-liquid interfaces. The bulk liquid mixture properties studied included the center of mass radial distribution functions, Kirkwood-Buff integrals (KBIs), volumetric properties, isothermal compressibility, enthalpy of mixing, dielectric constant, and diffusion coefficients. The vapor-liquid interface properties investigated included the relative surface probability distributions, surface tension, excess surface adsorption, preferred surface molecule orientations, and the surface dipole. None of the three FFs tested here was clearly superior for all of the properties examined. All the force fields typically reproduced the correct trends with composition for both the bulk and interfacial system properties; the differences between the force fields were primarily quantitative. The overall results suggest that the polarizable FFs are not, at the present stage of development, inherently better able to reproduce the studied bulk and interfacial properties-despite the added degree of explicit transferability that is, by definition, built into the polarizable models. Indeed, the specific parametrization of the FF appears to be just as important as the class of FF.

  17. Determination of multicomponent contents in Calculus bovis by ultra-performance liquid chromatography-evaporative light scattering detection and its application for quality control.

    PubMed

    Kong, Weijun; Jin, Cheng; Xiao, Xiaohe; Zhao, Yanling; Liu, Wei; Li, Zulun; Zhang, Ping

    2010-06-01

    A fast ultra-performance liquid chromatography-evaporative light scattering detection (UPLC-ELSD) method was established for simultaneous quantification of seven components in natural Calculus bovis (C. bovis) and its substitutes or spurious breeds. On a Waters Acquity UPLC BEH C(18) column, seven analytes were efficiently separated using 0.2% aqueous formic acid-acetonitrile as the mobile phase in a gradient program. The evaporator tube temperature of ELSD was set at 100 degrees C with the nebulizing gas flow-rate of 1.9 L/min. The results showed that this established UPLC-ELSD method was validated to be sensitive, precise and accurate with the LODs of seven analytes at 2-11 ng, and the overall intra-day and inter-day variations less than 3.0%. The recovery of the method was in the range of 97.8-101.6%, with RSD less than 3.0%. Further results of PCA on the contents of seven investigated analytes suggested that compounds of cholic acid, deoxycholic acid and chenodeoxycholic acid or cholesterol should be added as chemical markers to UPLC analysis of C. bovis samples for quality control and to discriminate natural C. bovis sample and its substitutes or some spurious breeds, then normalize the use of natural C. bovis and ensure its clinical efficacy. PMID:20155752

  18. Isothermal liquid-vapor equilibria of mixtures containing organic compounds. 2. excess Gibbs free energies of a hydrocarbon or tetrachloromethane + a cyclic ketone at 298. 15 K

    SciTech Connect

    Matteoli, E.; Lepori, L. )

    1988-07-01

    Vapor-liquid equilibrium data for mixtures of heptane, cyclohexane, tetrachloromethane, or benzene with cyclopentanone or with cyclohexanone were determined at 298.15 K by headspace gas chromatographic analysis of the equilibrated vapor phase. Excess molar Gibbs free energies G/sup E/ for the examined mixtures were obtained by a least-squares treatment of the equilibrium results. G/sup E/ are positive for all systems except for benzene + cyclohexanone and, for each given cosolvent, are in the order cytclopentanone > cyclohexanone and heptane > cyclohexane > tetrachloromethane > benzene. Activity coefficients at infinite dilution as well as free energies of solvation were evaluated for all the solutes in all the solvents investigated here.

  19. Probing hydrogen-bonding in binary liquid mixtures with terahertz time-domain spectroscopy: a comparison of Debye and absorption analysis.

    PubMed

    Tan, Nicholas Y; Li, Ruoyu; Bräuer, Pierre; D'Agostino, Carmine; Gladden, Lynn F; Zeitler, J Axel

    2015-02-28

    Terahertz time-domain spectroscopy is used to explore hydrogen bonding structure and dynamics in binary liquid mixtures, spanning a range of protic-protic, protic-aprotic and aprotic-aprotic systems. A direct absorption coefficient analysis is compared against more complex Debye analysis and we observed good agreement of the two methods in determining the hydrogen bonding properties when at least one of the mixture components is protic. When both components are aprotic, we show that the trend in absorption coefficients match well with the theoretical trend in strength of hydrogen bond interactions predicted based on steric and electronic properties of the components.

  20. Simplified computation of macrosegregation in multicomponent aluminum alloys

    SciTech Connect

    Mo, A.; Thevik, H.J.

    1998-08-01

    An approximate method for calculating the macrosegregation in a multicomponent aluminum alloy is proposed. This method is based on the use of a predefined solidification path (i.e., relation between the solute concentration in the liquid phase and the solid fraction) instead of addressing the fully coupled micro-macrosegregation problem. In determining the solidification path, it is assumed that the total solute concentration is constant, and that the solidification history is the same everywhere in the casting. In this manner it becomes quite easy to take into account how the macrosegregation development is affected by the solute diffusion in the dendrites and the precipitation of secondary cation path. In order to demonstrate the approximate method, the inverse segregation formation at a chill surface of an Al-4 pct Mg-0.2 pct Fe-0.15 pct Si-0.3 pct Mn (AA5182) alloy is calculated. The accuracy of the approximate method is discussed by considering a binary alloy. It turns out that the macrosegregation formation at a chill surface of an Al-4 pct Mg alloy is fairly close to that resulting from a modeling in which the variation of the total solute concentration is taken into account. Furthermore, the mixture law is compared to a more elaborate treatment of the densities involving both primary and eutectic solid phases. This comparison is carried out for an Al-4.5 pct Cu alloy for which literature data exist. The mixture law is found to give a reasonable accuracy in the calculated macrosegregation.